Carborane crosslinked silicone-based polymeric encapsulants for solid state lighting and display applications  (more...)

Researchers at the University of California, Irvine (UCI) have developed a microscope set-up that studies the effects of uniaxial and biaxial mechanical loading on a substrate in real-time. (more...)

Silicon nanostructures have attracted enormous attention in the past two decades due to their unique optical properties that cannot be observed in their bulk counterparts. However, since intrinsic silicon has negligible response to infrared photons (λ>1.15 μm) with energies lower than its bandgap energy, it poses a great challenge to use silicon as an active absorbing material for infrared photodetection. In order to realize all-silicon CMOS compatible infrared photodetectors, various approaches have been investigated including incorporation of germanium with silicon as the optically responsive element, two photon absorption process, and surface-plasmon Schottky detectors. The success of these earlier approaches has been limited. (more...)

The Eye Phone Dock is a universal smartphone adaptor for taking pictures or videos through an eyepiece of an optical device such as slit lamps, microscopes, and telescopes. (more...)

This invention is a new process to create microlens arrays and microwells in plastic.Microlenses are primarily fabricated from glass and optical grade polymers. One such plastic is polystyrene (PS), which has a high index of refraction, high optical transmission, and spectral band pass. Glass microlens array production is comparatively older but polymers have been favored for their affordability and ease of manufacture as well as the ability to control their thermal and mechanical properties. Previous methods for polymer arrays include: photoresist reflow, microjet printing, and direct laser writing. High temperature reflow of photoresist to create such rounded high aspect ratio structures is difficult and often results in rather shallow lenses. Then, to transfer the patterns into hard plastics via hot embossing, costly and slow electroplating is required. Instead, we created our molds using a laser jet printer and a technique which solves the shortcomings of modern manufacturing techniques. We address the issue of microfabricating high aspect ratio structures with high curvature (deep and round). Reflow of photoresist, the common way to make such structures typically results in shallow radii of curvature structures. Moreover, to transfer such structures to hard plastics typically require hot embossing, which requires a metallized (e.g. nickel electroplated) mold. This is very slow and expensive. Our technique allows our masters to be created with a laserjet printer. Then we can do soft lithography to transfer this to PDMS. Finally, we use the PDMS mold for the hot embossing back into a thermoplastic sheet. One problem solved by plastic microwells is the culturing of embryoid bodies (EB). EBs require size, morphology, uniformity and reproducibility control. Previous methods often required a trade-off between quantity and uniformity. PDMS microwells were a great improvement and did much to address these concerns. PDMS have the drawbacks of non-selective absorption, swelling, and poor mechanicalproperties. Polymer microlens arrays have been seen to have much potential but popular techniques for fabrication have various problems. For example,photoresist reflow suffers from chemical and thermal instability, has high requirements for consistency and reproducibility, and need photosensitive material. Some such disadvantages have been overcome but very often require expensive equipment and a time consuming process. This is new method of creating features on the microscale. The inverse of features previously formed in polydimethylsiloxane (PDMS) is transferred to a thermoplastic such as prestressed polystyrene. This is performed by placing the thermoplastic on the PDMS mold, forcing the substrates towards one another through uniform pressure, and baking them past the glass transition temperature of the thermoplastic. Inherent in this process are the multitude of techniques to pattern in PDMS and the ability of thermoplastics to become malleable when properly heated. The purpose of this is to create microstructures that may be used in various applications such as embryoid body culture or optical communication and interconnection. To demonstrate ability of the microlens arrays, we conducted a simple laser experiment was performed. As the laser was shown through the 460 um microlens array a z-stack of images were acquired. Using this information the numerical aperture for several lens were calculated to approximately 0.14. With this demonstration the functionality of this new microlens array design has been proven. This new, inexpensive and relatively simple method to fabricate microlens arrays in a hard plastic with excellent optical properties can provide a platform for optical applications. (more...)

University researchers have developed methods to synthesize structured glassy carbon nanofibers inside the pores of a porous silicon template by carbonization and obtain free-standing nanofiber by dissolution of the porous silicon template. The carbon nanofibers adopt the shape and morphology of the porous silicon template. The carbon/porous silicon composites are robust, surviving repeated thermal and organic vapor adsorption cycles. The carbon nanocasting approach creates surfaces that: (a) have increased affinity for non-polar organic molecules such as toluene, leading to a 10× improvement in the sensitivity of the sensor; (b) have increased surface area relative to the template leading to greater capacity as an adsorbent; (c) are very stable; and, (d) uniformly cover the underlying silicon layer. (more...)

A new technique for integrating ultra-low loss waveguides (ULLWs) with active silicon photonics. (more...)

A polarized LED and a method of fabricating and packaging the device. (more...)

New LED structures that provide increased light extraction efficiency while retaining a planar structure. (more...)

A phosphor-free white light source, where an indium-containing light-emitting layer, as well as subsequent device layers, is deposited on a textured surface. (more...)

Optical trapping systems are commercially available through several companies. In these systems, the optical trap precision relies on the passive stability of the instrument itself, and therefore demands costly engineering solutions to limit environmental noise that can be coupled into the optomechanical components. Consequently, high-resolution measurements are not possible in common biological laboratory settings that typically lack appropriate vibration isolation and temperature stability.  Researchers at the University of California, Berkeley have developed an invention that addresses a critical problem currently limiting the performance of high-resolution optical traps: that the mechanical drift of optical components often results in physical drift in the location of an optical trap that obscures the displacement-of-interest. The motion of biological motor proteins that are specific to interacting with DNA often take steps along the double helix that is on the order of 0.3 nanometers in size. Accurate measurement of displacements on this scale requires that drift of the trap positions be limited to no more than a few angstroms. However, the current best-performing optical traps suffer from instrumental drift that is almost twice what can be tolerated. Owing to the critical role of these components in all optical trapping systems, and the previously undetectable levels of mechanical drift they undergo, we sought to measure the trap drift with angstrom-level precision using a new approach. This new approach has successfully measured for and corrected for the mechanical drift of these components and demonstrated that this novel invention is capable of consistently reducing the noise floor to levels that have not previously been accomplished.        (more...)

University of California researchers have invented a high-power and low drive voltage electroabsorption modulator structure, utilizing two most popular materials for optoelectronics. The device design reduces the detrimental optical saturation effect in EAMs, while also improving the modulation efficiency. The advantages of the invention include high optical power operation due to improved optical power handling capability; lower modulation switching voltage; operation over a wide wavelength range due to a relatively large detuning energy, and likely lower insertion loses. EAM components made with this invention will greatly enhance the performance of optical fiber communication links. (more...)

Semiconductor lasers generate a large amount of undesired spontaneous emission before starting lasing oscillation, which degrades their efficiency and performance substantially. Therefore, lasers that emit almost no spontaneous emission have long been sought. Such 'thresholdless lasers', - where light output versus excitation power has no obvious threshold characteristic - lasing occurs at extremely low excitation powers. These lasers' superior performance is suited to optical applications. Currently there are two main approaches to designing nanolasers. The first utilizes dielectric based structures. Dielectrics have low loss at optical frequencies. There are, however, drawbacks in using dielectric-based nanolasers: they are either large in size or their mode extends far out of the gain region, and thus they exhibit poor gain-mode overlap. The other approach uses metal in a cavity. In recent years, nanoscale metallic, plasmonic, and metallo-dielectric cavities have shown to confine light in ultra-small volumes and to improve the gain-mode spatial overlap. However, existing metal-based nanolasers require high threshold pump power because of the significant absorption loss of the metals at optical frequencies. (more...)

This invention achieves a highly efficient defragmentation of spectrum in an optical telecommunications network (quasi-hitless). Using this technique, spectrum may be completely defragmented between connections in less than 400 ns, regardless of how the spectrum is allocated initially and with ho need for global synchronization. (more...)

Microfluidic devices are poised to revolutionize environmental, chemical, biological, medical and pharmaceutical detectors and diagnostics. The term “microfluidic devices” loosely describes the new generation of instruments that mix, react, count, fractionate, detect, and characterize samples in a micro-electro-mechanical system (MEMS) circuit manufactured through standard semiconductor lithography techniques. Although a wide array of microfluidic technologies are currently available, novel MEMS fluidic systems are needed as scientists continue to work with smaller sample volumes and desire devices with increased sensitivity and effectiveness. Researchers at the University of California, Irvine have developed a unique non-contact system for sorting monodisperse water-in-oil emulsion droplets in a microfluidic device. The technology can be coupled to other on-chip processes to increase device efficiency by sorting out un-reacted droplets. (more...)

A novel light-emitting device structure that reduces the effects of these misfit dislocations by maintaining low carrier loss in the active region of the device. (more...)

A novel LED structure that shows reduced droop effects when driven with high currents. (more...)

A novel method for growing group-III nitride crystals for use as seeds for ammonothermal growth of group-III nitride crystals. (more...)

Tachycardia is a type of abnormally fast heart beating arrhythmia-a heart rate greater than 100 beats per minute at rest, whose symptoms include palpitations, dizziness, angina, heart failure, or ultimately a heart attack. One of the commonly used non-surgical methods to treat this disease is Radiofrequency Ablation (RFA). Physicians guide a catheter with an electrode at the tip to the area of the heart muscle where there is an accessory extra pathway where heart cells give off the electrical signals that stimulate the abnormal heart rhythm. A radiofrequency energy is transmitted to the pathway and destroys carefully selected cells in a very small area. By doing so, the area stops conducting the extra impulses that cause the tachycardia. Researchers at the University of California, Irvine have developed a novel therapy modality, which combines optical coherence tomography and ultrasound with a electrophysiology catheter for real-time monitoring of the RFA treated area of the heart. The invention will provide images with high resolution and high penetration depth. (more...)

A method of fabrication for a novel photonic device with an integral guide for proper alignment of optical signal carrying apparatuses. (more...)

A novel VCSEL-based multi-wavelength transmitter and receiver module that support multi-wavelength transmission over a single optical fiber or a free-space optical link. (more...)

A novel VCSEL cluster for use in high power applications. (more...)

A fabrication technique for making a novel type of VCSEL with enhanced second harmonic generation. (more...)

A novel wavelength monitoring system that provides feedback to the laser, enabling it to lock to any given wavelength within its tuning range. (more...)

An integrated wavelength-tunable optical wavelength converter. (more...)

A long wavelength VCSEL that is optically pumped by a shorter wavelength VCSEL and is particularly useful for fiber-optic communication systems. (more...)

A method of fabricating diode lasers whose performance is essentially unchanged over designed temperature and bias ranges. (more...)

A wavelength-division-multiplexed array of long wavelength vertical cavity lasers, pumped by a short-wavelength optical pump. (more...)

A low cost and low complexity tunable laser source and monolithically integrated optical modulator. (more...)

Conventional approach to controlling and modulating carrier transport in transistor is by utilizing external electric field. In a typical setting, metal or heavily doped silicon gate is separated by dielectric materials from the active region of semiconductor, forming a metal-insulator semiconductor structure. However, such approach requires physical metal interconnections to the device for electrical modulation, which are constructed up to at least 10 interconnection layers in the state-of-the-art complementary metal-oxide-semiconductor (CMOS) technology. As the technology advances, these interconnections become more and more complicated, and significantly burden the operation of the transistor due to increased parasitic components of the circuit (i.e. parasitic resistance/capacitance). In order to address such challenges, researchers at the University of California, Berkeley have developed optical interface capable of wireless modulation of electrical current, instead of complicated physical metal interconnects. In particular, they have developed a interface to demonstrate the free-space optical modulation of current. The new capability of optical modulation allows a new class of transistor optical transistor - with unprecedented performance and tunability. Furthermore, The two critical applications of the new transistor - multi functional logic gates, and ultra-sensitive electrical detection of biomolecules – enable completely new possibilities for multifunctional electronics and ultra-sensitive detection of chemical and bio- molecules. The uniqueness of wavelength-specific modulation of nanophotonic transistors lead to the creation of multi-functional nanophotonic logic gates and circuits where different component generate multiple functionalities in a same circuit layout. In addition, local field enhancement provides a unique opportunity to substantially improve sensitivity of field-effect transistor (FET) based biosensors. (more...)

A method for growing an improved quality device by depositing a low temperature magnesium doped nitride semiconductor thin film. (more...)

Methods for successfully growingplanar non-polar m-plane gallium nitride (GaN) with metalorganic chemical vapor deposition (MOCVD). (more...)

Multiple-light source LEDs that provide increased light extraction and conversion efficiencies, as well as increased brightness, while retaining planar structures. (more...)

Researchers at the University of California, Irvine have developed a method using nonlinear optical (NLO), femtosecond infrared lasers for the precise depth and area activation of photosensitizers to treat the cornea. (more...)

A light emitting diode (LED) that combines a high-efficiency LED chip with shaped phosphor layers to increase the total luminous efficacy of the device.(UC Case 2007-272 and 2007-273) (more...)

A device with increased efficiency by combining shaped high refractive index elements with an (Al, Ga, In)N LED and shaped optical elements. (more...)

A safe etching technique for use with (Al, In, Ga)N materials. (more...)

Highly-efficient cleaved facet edge-emitting laser diodes grown on semipolar gallium nitride substrates. (more...)

Dual-beam optical traps, used in conjunction with microfluidic channels, are used for manipulating µm-scale dielectric objects such as biological cells or polystyrene beads. This type of manipulation is helpful for studying the mechanical properties of soft particles and the dynamics of particles suspended in microfluidic flows, and for holding and observing living cells over extended periods of time. However, optical traps/microfluidic systems suitable for practical applications have been quite complicated and expensive to make, primarily due to the difficulties of holding optical fibers in place mechanically on the chip or of using in situ optical wave guides or lasers as substitutes for optical fibers. Of particular concern is the need to incorporate complex microfabricated components into a system’s design to make it compact enough for use with microscopes. (more...)

Researchers at the University of California, Irvine have developed a novel method for capturing cellular resolution images of biological tissue at depths of up to several millimeters. Conventional fluorescence detection methods utilize microscope objectives for emission light collection, a less effective approach that is only capable of imaging up to one millimeter deep.To improve upon this standard, the UC researchers minimized light losses by optimizing the system’s excitation and detection optics. (more...)

A nonreciprocal ring resonator implemented in a ring isolator, which has the main advantages of miniaturization and integration with other optoelectronic devices. The isolator increases stability and reduces noise in optoelectronic circuits due to a high isolation ratio, which is measured at 9 dB in 1550 nm regime. (more...)

Method of coating luminescent phosphors, for lighting and display applications, with nanoscale ZNO films using atomic layer deposition (ALD) - for improved efficacy, thermal stability, and lifetime. (more...)

Mode-locked lasers are widely used to produce ultrashort light pulses (in the femtosecond range), for use in science and industry. Poor dispersion compensation, also called chirp, is a limiting factor in reducing the pulse length in many of these systems. While linear chirp can be eliminated with simple and mature technology—grating pairs, chirped mirrors, dispersion-compensating fibers, etc.—higher-order chirp is more difficult to eliminate. One approach to eliminating higher-order chirp is to use a programmable spatial light modulator—for example, a liquid-crystal or acousto-optic modulator—in the Fourier plane of a grating pair. These modulators, however, are very expensive, easily damaged, and absorb some of the light. Deformable mirrors can perform a similar role, but are also very expensive. Other approaches to tunably compensate higher-order chirp require extra optical components that make them difficult to align and adjust. Still other approaches are not tunable, or else tunable over only one degree of freedom. The present invention is an optical component that compensates higher-order chirp. It is very inexpensive and simple to manufacture, has low light loss, and has enormous damage threshold. Most importantly, it has three independent degrees of freedom, which adjust linear chirp, quadratic chirp, and cubic chirp. Each of these adjustments requires no realignment: Only the component itself needs to be adjusted. Therefore the invention could have widespread use, both as an OEM component of commercial lasers, and also as an easily-implemented upgrade to legacy systems. (more...)

The invention extends the dispersion limited reach of fiber optic cable to at least 500 km relying on simple OOK signaling, requiring no additional complexity in the transmitter such as additional amplitude or phase modulators. In addition the invention allows deployment of higher spectral efficiency systems based on OOK signaling and can increase the spectral efficiency of the existing system 2-5 times. The limit of 500 km is set by the currently available technology and it is conceivable that it can be increased with advancement in the realizable integrated circuits. Dispersion limited reach in uncompensated fiber optic links based on bit-by-bit detection is defined by the intersymbol interference (ISI). The dispersion limited distance for NRZ format is approximately 80-100 km. In 2001 electronic dispersion compensation (EDC) was suggested for extraction of information from ISI corrupted optical links. The dispersion limited reach with EDC is ultimately confined by the amount of spreading of the optical waveforms and in previous work, it has been shown that links operating at 10 Gb/s are limited to approximately 200 km with EDC. The limit is set by the increased complexity of the equalizer that grows exponentially with the span of ISI. With the technology of the present invention, this limit can be extended by up to 250%. (more...)

Researchers in the School of Engineering at The University of California, San Diego, have developed, and experimentally demonstrated, a VCSOA-like device that exhibits gain, bistability, and polarization selectivity to achieve Boolean inversion in the optical domain.  Similar set-ups and methods can be used to achieve other optical logic, switching, as well as memory devices and systems. Logic devices based optical cross-gain modulation (XGM)  in SOAs to achieve optical inversion suffer from the need to operate at high power (near saturation), have low bandwidth, and high coupling losses due to their quantum-well structure.  The present invention avoids these limitations and has the potential to achieve Boolean inversion at high speeds, low power, workable noise margins for cascadability because of input output isolation. (more...)

Researchers in the School of Engineering at the University of California, San Diego, have developed a new method for polarization-independent single photon wavelength up-conversion using optical coupling between a primary infrared (IR) Single Photon Avalanche Diode (SPAD) and a CMOS Silicon SPAD. A primary infrared photon induces an avalanche in the IP SPAD.  The photons produced by hot carrier recombination are subsequently sensed by the Silicon SPAD, thus allowing for on-die data processing.  Advantages over existing state-of-the-art approaches are minimal power dissipation (1 pW compared to 300 mW), compact solid state device fabricated using proven mass production methods, and can be scaled to large arrays.  Reduced after-pulsing is also suppressed compared to present day SPADs. (more...)

A new avalanche photodiode that is low noise and provides a highly stable gain at small bias voltages. (more...)

Aerodynamic lenses are now widely used as a method to generate a particle beam, particularly for small nanoparticles. Aerosol mass spectrometers are commercially available and their integrated aerodynamic lens-nozzle designs has been characterized. [See, for example, Aerosol Science and Technology, 36, 617-631, (2002).] However, the technique has the serious limitation that it is limited to particles > 10 nm. (more...)

Effective optical imaging design is critical for a solar energy system such as concentrating photovoltaic and concentrating solar thermal. One of the design goals is to produce high solar flux and a desirable uniform irradiance on the photovoltaic cell, which further convert lights into electrical output effectively. Previous solution was to use kaleidoscopic prism. However, the kaleidoscopic glass mixer is bulky, the material is expensive for mass production, and the mounting is difficulty. A promising new solution based on combining aplanatic optics with Köhler illumination has been invented. (more...)

Luminescent solar energy concentrators can concentrate both diffuse and direct solar radiation and require no tracking system. These characteristics have advantages for providing the devices and techniques to improve the efficiency of solar power systems. However, for the technology becomes economically viable in the marketplace and cost competitive with the conventional forms of solar energy systems, the overall power generation efficiency of the system needs to be increased. Previous works demonstrated the application of luminescence to concentration of solar radiation by applying optical waveguide technology, which guides the frequency-shifted light via total internal reflection (TIR) to an energy transducer that comprises a photovoltaic cell. The typical conversion efficiencies achieved have been in the 3% to 5% range. The present invention discloses an improved apparatus design that significantly increases the overall conversion efficiency of the system. (more...)

Solar concentrators are relatively compact optical components that concentrate sunlight to heat a working fluid or to generate electricity from photovoltaic cells at higher efficiencies than is possible from unconcentrated sunlight. In the case working fluids, higher efficiencies are due to the higher working temperatures realized. For photovoltaic applications, concentrators can greatly economize on the use of expensive photovoltaic cell materials. A common solar concentrator design employs a refractive material that admits light on one surface and a combination of internal reflections to concentrate and focus the light on a small spot on another surface using a Cassegrain-type optical pathway. The efficiency of such a system is limited, however, by unavoidable optical aberrations—minimizing such aberrations with an aplanatic concentrator design is necessary for achieving the thermodynamic limits of concentrator efficiency. Dielectric layers or other special materials facilitate the most compact concentrator designs, but conventional design methods (based on rotations of 2-dimensional mathematical solutions for correcting optical aberrations) are very difficult to calculate and implement due to the complex shapes of the resulting surfaces and the requirements of compact designs. (more...)

Researchers at UCI’s MicroSystems Laboratory have developed a process and design to form a highly reflective coating for the angled sidewalls of a miniature cavity for vapor cells. These coatings are for micro-optical elements or micro-optical-electrical-mechanical-systems of MOEMS. The applications of these coatings include miniaturized atomic clocks for ultra precision time keeping and magnetometers for the sensing of magnetic fields. (more...)

Breast density has been shown to predict the individual woman’s risk of developing breast cancer, We have developed a new method to analyze breast density based on Magnetic Resonance Imaging (MRI). A similar system for analyzing breast density based on 2-dimensional mammogram is commercially available. Our new method is based on MRI, which acquires 3-dimensional images and can be used to analyze not only the amount of dense tissue, but also the morphological distribution of the dense tissue. This invention allows for the analysis of the density of breast. This information may be used to provide a better management plan for patients receiving breast MRI. (more...)

In analog fiber optic links, high optical power is desirable to improve the link gain and signal-to-noise ratio. However, todays fast photodetectors tend to saturate at very low optical power because of small active areas and high optical power density. Additionally, although high speed operation has been demonstrated in surface-illuminating type photodetectors, they are limited by the trade-off between bandwidth and efficiency. Recently, waveguide photodetectors have overcome the above trade-off. However, their main disadvantages are the low optical coupling efficiency from optical fibers and also low optical saturation power. Thus, the increase of the internal quantum efficiency is often offset by the low coupling efficiency. The above disadvantages have led to the need for new ultrafast photodetectors with high efficiency and high optical saturation power. (more...)

Polymer thin films have been used for surface engineering of inorganic and organic substrate surfaces to enhance substrate chemical selectivity and modify surface topology in such areas as biotechnology, tribology, chromatography, chemical sensors and separation technology. Thin polymer films which are applied via traditional spin-coating or surface adsorption have low thermal and chemical stability which can lead to film dewetting and surface degradation.Covalently bonded polymer films can be formed by graft polymerizing a suitable monomer onto substrate surfaces via the use of free-radical initiators, cationic/anionic initiators, or by using a combination of a catalyst and initiators for controlled graft polymerization. Yet each of these techniques relies on the presence of initiator sites which must be first covalently grafted to the surface by techniques such as silylation, self assembly, or functionalized molecules that act as anchoring sites for monomer grafting. It is noted that in the case of inorganic oxide surfaces, the surface density of initiation sites is limited by the intrinsic availability of native surface hydroxyl groups which typically serve for attaching the active anchoring species to the substrate. Alternative methods of graft polymerization that are based on surface activation via low pressure plasma surface activation have also been developed. However, such approaches are expensive, impractical for large-scale applications and are also difficult to control. (more...)

This invention is a part of a research effort that will enable a quantam leap in the performance of high bit rate optical communication systems. The research products of this effort will include femtosecond semiconductor lasers with high pulse energy.Monolithic mode-locked semiconductor lasers generating sub-picosecond optical pulses with high pulse energy play an important role for electro-optic sampling and high bit rate TDM systems. Though such short optical pulses have been demonstrated in semiconductor gain medium using external cavities and additional pulse compression, those lasers are very bulky and not suitable for practical applications. Monolithic mode-locked semiconductor lasers are compact, light weight, energy efficient and do not require optical alignment. Although very impressive performance (600 fs pulse width, 350 GHz repitition frequency) has been demonstrated, the pulse energy of this type of multiple-contact quantum well lasers is limited by the intra-cavity saturable absorber (approx.10 fJ). Such energy is insufficient for most all-optical switching/demultiplexing systems.The subject invention is a new integration scheme for realizing novel femtosecond semiconductor lasers with an integrated antiresonant Fabry-Perot saturable absorber (A-FPSA). Such lasers have several unique advantages: (1) ultrashort pulse generation that fully exploits the gain bandwidth of semiconductor quantam wells; (2) high power operation (average power > 50mW) because the saturable absorber is placed inside the antiresonant FP cavity; (3) it enables intra-cavity dispersion compensation for the first time in monolithic cavities, which could further shorten the pulse width (the gain bandwidth of semiconductor could support pulses as short as 50 fs). These performances represent one to two orders of magnitudes improvement over the conventional monolithic mode-locked lasers. In this scheme, the saturable absorber is decoupled from the gain medium and, therefore, can be separately optimized for shorter pulses. For example, it can be made into fast saturable absorber by employing low-temperature grown GaAs. (2) By placing the saturable absorber layer inside an antiresonant Fabry-Perot cavity, its saturation energy can be increased by 100 times (1 to 10 pJ). Thus much higher peak/average power can be obtained from the proposed femtosecond semiconductor laser. (more...)

This innovation is a Bragg-grating scheme developed on a silicon-on-insulator platform. It serves as a building block for optical components, such as filters, modulators, and resonators. This device consists of a silicon waveguide sandwiched between two rows of periodic silicon cylinders, set a fixed distance away from the waveguide. The coupling strength and dynamic range is easily varied by increasing or decreasing the separation distance between the periodic cylinders and the waveguide, giving excellent control of the coupling within the Bragg-grating and enabling filters of narrow to wide bandwidths. This approach is believed to be the first wherein the coupling strength in a Bragg-grating can be well controlled and predictably yield narrow bandwidth filters. (more...)

Porous silicon (PSi) is a particularly attractive material for biological and high-tech applications because of the ease with which the optical properties, pore size, and surface chemistry can be manipulated. The position, width and intensity of spectral reflectivity peaks are controlled by current density, waveform and solution composition used in the electrochemical etch. This allows the preparation of PSi photonic crystals that can display any number of colors within the visible spectrum with high color saturation and resolution, highly desirable features for information display. Researchers at UC San Diego have converted these films into micron-sized particles (so-called “smart dust”, described in: Link and Sailor, Smart Dust: Self-assembling, self-orienting photonic crystals of porous Si.; Proc. Nat. Acad. Sci., 2003, 100 (19): p.10607-10610). (more...)

The generation of electricity from sunlight is currently not cost-effective in many situations because of the inherent limitations of photovoltaic (PV) cells and typical lighting conditions. The production of commonly-used silicon PV cells demands expensive semiconductor fabrication methods and consumption of limited high-grade silicon feedstocks. Newer thin-film cell technologies, while using cheaper fabrication methods, consume even scarcer exotic materials. Moreover, at typical sunlight intensities, PV cells are relatively inefficient, requiring large panels for a given peak power output. To reduce costs, it is desirable to increase PV cell efficiencies while minimizing the use of costly materials and fabrication techniques. One promising way to accomplish this is with concentrator PV (CPV) systems, where an inexpensive optical element (usually made of glass) covering a large sun-lit area is used to greatly concentrate the light onto a small PV cell. Higher light intensities enable higher efficiencies in converting sunlight to electricity while greatly reducing the size of the PV cell required. One important limitation of CPV, however, is the need to keep the concentrator surface aligned with the sun. For CPV to become cost-competitive with conventional PV technology, CPV designs must become less stringent in their alignment requirements (i.e. higher acceptance angles). (more...)

This invention presents a novel cardiac imaging processing method, the tomography-based dynamic cardiac elastography (DCE) method for in vivo identification of the passive nonlinear viscoelastic properties and active contractility of myocardium of an individual heart. (more...)

The generation of electricity from sunlight is currently not cost-effective in many situations because of the inherent limitations of photovoltic (PV) cells and typical lighting conditions. To reduce costs, it is desirable to increase PV cell efficiencies while minimizing the use of costly materials and fabrication techniques. One promising way to accomplish this is with concentrator PV (CPV) systems, where an inexpensive optical element (usually made of glass) covering a large sun-lit area is used to greatly concentrate the light onto a small PV cell. Higher light intensities enable higher efficiencies in converting sunlight to electricity while greatly reducing the size of the PV cell required. Optimization of solar concentrator design depends on maximizing light concentration and optical efficiency while enabling facile alignment of the system with the sun. (more...)

Novel LEDs, where the emission region is structured in order to have efficient light extraction. (more...)

A method of fabricating solid state lasers with embedded structures for improved performance via patterning. (more...)

UCI researchers have developed a laser system for the generation of pulses with duration in the picosecond range and a narrow bandwidth. The laser system produces pulses with a duration of about 25 ps. The radiation can be tuned between 410 nm and 2000nm. The bandwidth of the radiation is spectrally narrow, close to the theoretical limit (the Fourier limit). Technically this system is an optical parametric oscillator (OPO); amplification is obtained in a parametric process rather than by population inversion. The oscillator is pumped by a pulse train from a Nd:Yag laser. In each roundtrip the bandwidth of the radiation is reduced by a grating-mirror assembly. Finally after a number of roundtrips a close to ideal pulse is obtained. This single pulse is then amplified by an OPA (Optical Parametric Amplifier) obtaining a single tunable narrow bandwidth pulse with a duration of about 25 ps. This source can be used for a number of spectroscopic techniques where ps pulses are needed as well as the highest achievable spectroscopic resolution. (more...)

Silicon-based device structures capable of laser emission are highly desirable since they allow realization of integrated opto-electronic circuits. Unfortunately, it is generally believed that silicon's inherent bandgap prevents its use, alone, as lasing media. Numerous approaches to overcoming this difficulty have been attempted with mixed results. Recently, high efficiency electroluminescence from silicon light-emitting diodes corresponding to silicon's bandgap energy has been reported. However, none of these approaches has been successfully used in current injection to achieve optical gain and stimulated emission, a key requirement for laser emission. (more...)

Large scale confinement chambers have been created in the past using traditional glass-blowing techniques. However, conventional glass-blowing can only be used to create large components and requires the components to be made one at a time. Micro-glass spheres have previously been fabricated by letting glass particles fall through a temperature-controlled drop tower. While it is possible to create hollow spheres by introducing a blowing agent in the glass, these micro-spheres are not attached to a substrate and are therefore difficult to integrate with micro-machined components on a wafer. (more...)

An important issue in laser treatment of cutaneous lesions is to protect the epidermis from thermal damage. This heating, which is primarily caused by light absorption in the melanosomes, can easily bring the temperatures of the basal layer above the threshold damage value of 65-70 degrees C. Pre-cooling of the epidermal basal layer from the ambient value of 35 degrees C to 0 degrees C increases the optical radiant exposure that can be safely delivered by a factor of two. Currently, selective epidermal cooling can be obtained by using a liquid spray of the cryogen R-134A (tetrafluoroethane) for 30-100 ms immediately before laser exposure. However, R-134A has a Global Warming Potential of 1,300 (GWP) and will soon be banned as refrigerant in Europe with the possibility of a future ban in the U.S. Thus a low GWP value substitute is needed. (more...)

Magnetometers are used for sensing magnetic fields. Applications include geophysical surveying, nuclear magnetic resonance imaging (MRI), magneto-encephalography and perimeter surveillance. Gyroscopes sense rotation. Together, these instruments are used in inertial navigation and platform stabilization such as anti-roll systems in cars. A variety of commercial magnetometers exist with various application areas. Superconducting quantum interference devices (SQUIDS) are highly sensitive but require cryogenic cooling. Atomic magnetometers are even more sensitive but run approximately $10,000 per unit. Commercially available gyroscopes run a similar gamut. (more...)

Laser scissors use lasers to alter and/or to ablate intracellular organelles, cellular and tissue samples, and today has become an important tool for cell biologists to study the molecular mechanism of complex biological systems. Single cells or groups of cells have been perforated for injection of exogenous materials, induction of DNA damage in cells, micro-dissection of neuronal processes, as well as other intra-cellular organelles such as chromosomes or microtubules. Clinically, laser scissors have been used to reduce the thickness of the zona pellucida layer of the ovum in order to improve human in vitro fertility. In these applications, either a scanning stage or scanning mirror was used to scan a region in a single cell or group of cells for micro-processing. This method is expensive and requires complex control of the scanning beam via computer. In addition, the processing time can be lengthy and reduces the throughput of the laser microbeam system. (more...)

Photodetection, especially for fluorescence applications, requires various optics including lenses and filters. The optics surrounding the detection and illumination system are complex and can often weigh more than the photodetector and illumination sources. Therefore in order to make such photodetection equipment mobile, much of the optics needs to be integrated and micro-sized. However that causes various microfabrication problems -- especially in yields and throughput. To address this situation, researchers at UC Berkeley have developed a new design for fluorescence detection subsystems. This new design integrates and miniaturizes the photodetection functionality and thereby makes it suitable for mobile application as well as efficient microfabrication. (more...)

Broadband mirrors with very high reflectivity are essential for applications such as telecommunications, surveillance, sensors and imaging. Among the various conventional mirror designs, metal mirrors have larger reflection bandwidths but lower reflectivities; as a result they are not suitable for fabricating transmission-type optical devices such as etalon filters. Dielectric distributed Bragg reflectors (DBRs) can achieve a higher reflectivity but deposition methods for DBRs are often not precise enough to yield the reflectivities of 99% or better needed for demanding applications, and typical material combinations constrain the mirror bandwidth and can be incompatible with conventional semiconductor processing technologies. In addition the tuning range is often limited for tunable etalon type devices such as MEM vertical cavity surface emitting lasers (VCSELs), filters, and detectors. There is a need for a mirror with broadband reflection, low loss, and compatibility with conventional optoelectronic processing methods. Researchers at the UC Berkeley have developed a single layer, sub-wavelength grating with a very broad reflection spectrum and very high reflectivity. The grating design facilitates monolithic integration of optoelectronic devices at a wide range of wavelengths from visible to far infrared, as well as integration with electronic circuits and other optoelectronic devices. Grating spectral characteristics can be tailored by choice of materials and structure to maximize both reflectivity and spectral coverage. The grating design developed at Berkeley has potential application in MEM tunable devices and reconfigurable focal plane arrays for such high value applications as optical communications, chemical/biological sensors, and imaging. (more...)

Approach in optical spectroscopy for the detection of ischemic tissue injury (more...)

Immunoassay on a Compact Disc (CD): Support With Interactive Data Storage (more...)

All-Optical Variable Buffer Queuing (more...)

High-Resolution Raster-Scanning Display Systems (more...)

The generation of electricity from sunlight is currently not cost-effective in many situations because of the inherent limitations of photovoltic (PV) cells and typical lighting conditions. The production of commonly-used silicon PV cells demands expensive semiconductor fabrication methods and consumption of limited high-grade silicon feedstocks. Newer thin-film cell technologies, while using cheaper fabrication methods, consume even scarcer exotic materials. Moreover, at typical sunlight intensities, PV cells are relatively inefficient, requiring large panels for a given peak power output. To reduce costs, it is desirable to increase PV cell efficiencies while minimizing the use of costly materials and fabrication techniques. One promising way to accomplish this is with concentrator PV (CPV) systems, where an inexpensive optical element (usually made of glass) covering a large sun-lit area is used to greatly concentrate the light onto a small PV cell. Higher light intensities enable higher efficiencies in converting sunlight to electricity while greatly reducing the size of the PV cell required. One important limitation of CPV, however, is the need to keep the concentrator surface aligned with the sun. For CPV to become cost-competitive with conventional PV technology, CPV designs must become less stringent in their alignment requirements (i.e. higher acceptance angles). (more...)

 Recent research focuses on the study on higher harmonics of the response of an atomic force microscope in tapping mode, which change characteristically with respect to the Youngs Modulus of the sample. Higher harmonics are excited more with harder materials. These higher harmonics can be mechanically preamplified with an appropriate construction or excitation of the system and be read out with the usual optical measurement units. (more...)

The University of California has a number of inventions in the field of ceramics and ceramics composites that are available for commercial licensing. These technologies include: Porosity—A combustion synthesis method that produces low-porosity, high-density ceramics (1995-263), a synthesis method that produces high-density ceramics with extremely fine crystallite sizes (2005-510), a one-step synthesis and consolidation of nanoparticles in ceramics, etc. (1999-355), and methods for producing high-porosity oxide ceramics (1997-186); Ductility—A method for making high-strength nanocrystalline materials with improved ductility (2003-539), an inexpensive, easy-to-fabricate ceramics matrix composite (1995-109), an improved method for making metal matrix composites using spray atomization (1994-134), a practical method for microalloying magnesium in molybdenum silicide (2002-237), and strong, flaw-tolerant ceramics laminate composites (1991-243 and 1999-385); Hardness—A thermal barrier coating with increased hardness and wear resistance (2002-164), a direct, one-step synthesis of titanium carbonitride cermets (1992-018), bulk metallic glasses with nanoscale crystallites (2003-334), and diamond-containing ceramic composites (1986-070); Functionally-Gradient Materials (FGMs)—A method for making layered FGMs with superior interlayer bonding (2005-223) and a simple, inexpensive one-step synthesis of metalloceramic FGMs that display a smooth transition in their compositional profiles (1992-027); and General Synthesis & Fabrication Methods—A system for post-machining inspection of manufactured ceramic parts (Ceramic Candling Inspection System), a method for preparing nanocrystalline coatings (1996-370), an improved method of combustion synthesis (1992-020), and a method for fabricating complex-shaped ceramics with a more uniform phase distribution (1990-317). SLIDESHOW PRESENTATION: More information about this invention portfolio is available in a slideshow presentation that can be downloaded from http://patron.ucop.edu/ncd/docs/ceramics.pps (4.1 MB). This file includes an audio narration and web links to non-confidential descriptions, issued patents, related publications, and inventor profiles. (more...)

Organic molecules that absorb two or more photons simultaneously have wide applications in a variety of technologies involving such subjects as optical data storage, 3-D microfabrication techniques, frequency upconverting lasing, optical power limiting, photodynamic therapy, initiators of polymerization reactions, and multi-photon fluorescence microscopy for biological imaging.   (more...)

Light-emissive polymers are outstanding laser materials because they are intrinsically "4-level" systems. Their luminescence efficiencies exceed 60%, even in undiluted films, they emit at colors in the full range of the visible spectrum, and they can be processed into optical quality films by spin casting. In recent years, remarkable progress has been made in implementing semiconducting polymer materials into different resonant structures for optically pumped lasers. Neat films with emission wavelengths ranging over the entire visible spectrum and high photo-luminescence illustrate the importance of this class of luminescent semiconducting polymers as gain media. Placing a thin film as the active material between two electrodes in a vertical cavity laser configuration offers one approach to injection lasers. However, electrically pumped laser emission has not yet been demonstrated due to the additional losses introduced by the metal electrodes and charge induced absorption. (more...)

Vertical-cavity surface-emitting lasers (VCSELs) have been used to implement tunable lasers by using a single active region and by tuning the resonance of the optical cavity incorporating that active region. However, lasers produced by these methods possess a limited wavelength range, as well as output power due to the limited bandwidth of the gain region. (more...)

Oxide and air apertures can enhance the performance of semiconductor lasers and detectors. However, in material systems that do not accommodate epitaxial incorporation of highly oxidizing materials of sufficient thicknesses, such apertures are difficult to implement. This is specifically the case in AlGaInAsP systems. In these situations, the materials' slow oxidation rates and/or limited thicknesses restrict their use as optical and/or current apertures. (more...)

Several commercially available signal-generating systems currently exist, such as Digital-to-Analog Converters (DACs), electronic Arbitrary Waveform Generators (AWGs), and Direct Digital Synthesizers (DDSs). However, limitations in synthesized waveform frequency and the ability to manipulate the waveforms (stretching, compression, and inversion) hinder the effectiveness of these systems for applications requiring high-frequency signals. (more...)

Typical vertical cavity lasers (VCLs) are formed from a layered semiconductor material which includes an oxidation region composed of a thin AlAs layer and an adjacent AlGaAs layer. A p-type distributed Bragg reflector (DBR) (p-mirror), formed of alternating layers of GaAs and AlGaAs, overlies the oxidation region, while an n-type DBR (n-mirror) underlies the region. The layered semiconductor material is then etched to form a circular pillar that contains the entire p-mirror and oxidation regions and may extend partially into the n-mirror region. A two-layer configuration of the oxidation region is used to produce a tapered oxide aperture, which lowers optical scattering losses and increases performance for the VCL. However, as with any oxide-apertured VCL, the efficiency declines due to lateral carrier diffusion away from the center of the active region as the VCLs are made smaller. This can be remedied with selective intermixing of the active region to prevent this diffusion, but such intermixing techniques require the VCL to undergo a high-temperature annealing process that considerably degrades and corrupts its structure. (more...)

The demand for faster data-transmission rates has led to considerable interest in developing high-capacity optical data links for short-haul local-area network and fiber-to-the-desktop applications. Most of the work done so far has focused on one-dimensional parallel optical data links that utilize multimode fiber ribbons with the one-data-channel-per-fiber arrangement. Even with a very complicated system configuration this results in a maximum aggregate data-transmission rate of only 2-3 gigabytes per second (Gb/s). The transmission capacity can be significantly expanded by using a wavelength-division multiplexing (WDM) configuration, which allows multiple data channels in each fiber. For this system to be commercially viable the corresponding transmitter and receiver modules must be low cost. (more...)

 In the approximately twenty years since its invention, the AFM has become more and more advanced, measuring smaller and smaller forces and utilizing smaller and smaller cantilevers. This has introduced problems relating to forming appropriate incident light beam spots on such very small cantilevers and in detecting cantilever deflection during scanning as well as when different cantilevers are brought into position for different uses. In addition, a fundamental limit is the source of noise in the AFM, generally resulting from thermal noise of the cantilever. With the use of smaller cantilevers, this noise source can be reduced such that very small forces can be measured in principle. However, with smaller forces, the deflections of the cantilever become smaller and the detection noise becomes more and more significant. Therefore, it is important to have a reliable, low-noise detection system. (more...)

Avalanche photodetectors (APDs) absorb and convert light to an electrical signal and then amplify that electrical signal through avalanche multiplication. Current devices have not achieved the desired efficiencies due to the trade-off between materials with good absorption properties and materials with low-noise avalanching properties. While it is advantageous to use one material to absorb and another to multiply the signal, current technology has limited these devices to only those materials that can be lattice matched. (more...)

When designing and fabricating materials (e.g., semiconductor devices), engineers need to monitor the composition and properties of samples. Typical analysis methods include atomic force microscopy, scanning optical microscopy, and transmission electron microscopy. Often more than one technique must be used to obtain the needed information. Making multiple analyses can be time consuming and delay the development of products. Scientists at the University of California have designed a method to fabricate multipurpose sensors on the tips of probes used in atomic force microscopes. The sensors can detect an optical, thermal, magnetic, electrical, or another signal from the surface of a sample. For example, the sensor can be fabricated so that the probe acts as a scanning near field optical microscope. Thus, an optical and a topographical image of a sample can be generated simultaneously. (more...)

: Mode-locked semiconductor laser are often used as compact, reliable, and inexpensive sources of short optical pulses. Although mode-locked lasers reliably show good noise performance at a wide range of repetition rates, they can only produce relatively low-energy pulses (approximately 2 mW). If these lasers could be used to generate high-power optical pulses, they would become an attractive alternative to the large, expensive, and difficult to maintain conventional benchtop laser systems, such as dye and Nd:YAG laser systems. Researchers have improved the output power of semiconductor laser by using an array of laser and by using post-amplification and pulse compression techniques. However, neither of these techniques has achieved substantial enough increases in pulse power to displace conventional laser systems. Researchers at the University of California have devised a more effective post-amplification method to increase the power of these laser optical pulses. The researchers have developed two general methods, both of which use modified semiconductor amplifiers, to achieve four-fold and greater power amplification with no loss of single-mode laser beam quality. (more...)