A method that uses wavelength routing devices such as arrayed waveguide grating routers (AWGR) and Echelle grating routers to realize a passive interconnection network with a reduced number of wavelengths to implement all-to-all interconnection. (more...)

University of California researchers have developed a method to overcome SIC by employing a technique where the primary antenna receives or transmits data while the secondary antenna cancels interference.  The waveform prefilters remove SIC from the transmitters to the receivers on the same radio at the radio frequency frontend.  This allows the transmitters and receivers to double their data stream at the same time while using the same frequency channel on the same radio.   (more...)

University of California researchers have developed a method for reducing electronic 1/f noise in graphene devices used for high speed applications and biological and chemical sensors.  Using a novel method of irradiating the channel regions of graphene devices with electron beams with proper irradiation dosage, the 1/f noise in a graphene device is suppressed.   (more...)

An optical signaling header technique applicable to optical networks wherein packet routing information is embedded in the same channel or wavelength as the data payload so that both the header and data payload propagate through network elements with the same path and the associated delays. (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...)

A novel method and apparatus to improve the overall quality of a reconstructed video signal at a given transmission rate, or to maintain the current signal quality at reduced transmission rates.  (more...)

A process for manufacturing a novel type of Vertical Cavity Surface Emitting Laser with low optical loss. (more...)

A novel Wavelength-Division Multiplexer device to interleave multiple signals into a multiplexed, multi-channel optical laser signal. (more...)

A novel VCSEL scheme in which an electrically-pumped short wavelength VCSEL is optically coupled to a long wavelength VCSEL for optically pumping the long wavelength VCSEL. (more...)

A novel method for creating a VCSEL structure that confines current diameter to less than that of the transverse optical mode, while maintaining a high degree of planarity in its layers. (more...)

A technique for achieving low-capacitance bonding pads for high-speed optical semiconductor devices such as lasers, detectors and modulators. (more...)

A process for use in fabrication of a semiconductor device that produces low loss refractive index guiding. (more...)

On-chip capacitively transduced vibrating polysilicon micromechanical resonators have achieved quality factor Q's over 160,000 at 61 MHz and larger than 14,000 at about 1.5 GHz -- making them suitable for on-chip frequency selecting and setting elements for filters and oscillators in wireless communication applications. However, there are applications -- such as software-defined cognitive radio, that require even higher Q's at RF to enable low-loss selection of single channels (instead of bands) to reduce power consumption down to levels conducive to battery-powered handheld devices. To address those higher Q RF applications, researchers at UC Berkeley have invented design improvements to MEMS resonators that reduce energy loss and in turn increase resonator Q. In reducing energy loss to the substrate while supporting all-polysilicon UHF MEMS disk resonators, the Berkeley design improvements enable quality factors as high as 56,061 at 329 MHz and 93,231 at 178 MHz -- that are values in the same range as previous disk resonators using multiple materials with more complex fabrication processes. Measurements confirm Q improvements of 2.6X for contour modes at 154 MHz, and 2.9X for wine glass modes around 112 MHz over values achieved by all-polysilicon resonators with identical dimensions. The results not only demonstrate an effective Q-enhancement method with minimal increase in fabrication complexity, but also provide insights into energy loss mechanisms that have been largely responsible for limiting Q's attainable by all-polysilicon capacitively transduced MEMS resonators. (more...)

A novel software that automatically and accurately synchronizes pre-segmented transcripts with corresponding videos. (more...)

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Given here is an innovative multiple sub-carrier selection diversity receiver architecture for WLAN OFDM systems with multiple antennas. With a small increase in analog complexity, it is shown that significant gain can be achieved by the proposed technique over selection diversity for WLAN OFDM systems. The technique requires only a single A/D and DFT, which eases the baseband hardware requirements significantly. (more...)

EdgeCasting is a network architecture and protocol for streaming high quality video to a large population at a low cost. This unique approach offers a high degree of utilization of network resources. (more...)

This invention describes a system for collecting, filtering, processing, and ranking information related to user-generated content in 3D virtual worlds such as Second Life® for the purpose of creating a search service for 3D content. (more...)

Current internet search engines are limited in their ability to search through web-based databases that are only accessible through front-end search pages. Although this information is hidden to the typical user, it is usually of high value. (more...)

UCLA researchers have developed an adaptive prefetch scheme that may be applied to almost any network application in which files on a remote server may be needed and for which it is possible to estimate the probability of accessing the files. The most obvious example is web browsing. This prefetch scheme has two main components: 1) an adaptive prefetch algorithm, which can be used to obtain files on remote servers before a user requests them, so that the average delay of accessing these files is reduced, and 2) a GUI, which adds icons to each web link on a page that indicate the quality and condition of the link to assist the user in deciding whether to access any particular link. Earlier prefetching schemes simply prefetch a fixed number of pages or pages above a fixed threshold value. These are not adaptive to network conditions, so there is often no real improvement on system performance. This new adaptive prefetch scheme predicts how likely it is that a user will request files based on access history. It determines not only which pages are requested, but also from which page the request is initiated. It also assesses the quality of the link based on the network capacity, system load, and takes into account the cost of bandwidth and usage time. This prefetch scheme can be incorporated into a Web browser, and the techniques may be applied in other caching applications as well. (more...)

The invention is a new technique for people to engage in behavior modification (smoking cessation, dieting, etc.) or explore mutual interests in a secure fashion via the Internet. A working prototype exists and is showing efficacy similar to chemical means for certain behavior modifications. Prototype exhibits the secure and interactive nature of the invention. (more...)

The effective management of surgical operating rooms (OR) is crucial for safe, high quality, patient care. However, this can be very challenging due to the number of staff, patients, and rooms involved, combined with the necessary coordination of equipment, medications, and supplies. To address this important issue, the UCSF OR has developed a novel, easy to use tool to visualize and manage OR use in real-time. (more...)

Video file synchronization between remote users is an important task in many applications. The term ''synchronization'' in this context refers to ''maintenance of the same version of files on multiple devices''. Re-transmission of a video that has been only slightly modified is expensive, wasteful and avoidable. University of California investigators have developed VSYNC (video-sync), a novel incremental video file synchronization system that automatically and efficiently detects and sends only modified content according to some user defined distortion constraint to enable rate savings under a wide range of video edits. Through the use of a low-rate hierarchical hashing scheme, can be detected with some spatial granularity. The novel contributions of VSYNC are: (1) only actual changed content of video data are transferred, rather than the whole video, which makes updates faster and cheaper, especially over slower links; (2) it can synchronize the video content within up to some pre-defined distortion, and the hash rate can be analytically determined given a target distortion, and (3) it is video-codec invariant. Experimental results show that the proposed approach achieves up to 7x rate reduction when compared to re-transmitting. The proposed system has a wide range of applications including video authentication, video storage/backup, video file sharing among multiple users and online video editing. The investigators, Hao Zhang, Chuohao Yeo, and Kannan Ramchandran, recent publication can be found at http://portal.acm.org/citation.cfm?id=1459479 (more...)

Optical Encoding Tool to Sculpt Ultra-Short Optical Light Pulses (more...)

All-Optical Multi-Protocol Router Portfolio (more...)

Innovations that enable optical network providers can now offer service level agreements assuring both continuous quality and guaranteed levels of protection from connectivity interruptions in mesh net operations (more...)

New image compression scheme with sharper images consisting of a PHLCT-based compression (more...)

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

In data networks employing optical time-division multiplexing (OTDM), each network node must carry out a number of key functions in order to efficiently process an optical signal that is modulated with both a data stream and timing signals. In particular, the processing of each channel within the signal requires simultaneous demultiplexing, packet add/drop, clock recovery and synchronization, and data stream regeneration. At present, incorporating all of these functions into an optical network node poses severe trade-offs between hardware complexity and cost on one hand and problems of channel ambiguity and cross-talk on the other. (more...)

Vertical-cavity surface-emitting lasers (VCSELs) at 1.55 micrometers are important in telecommunications networks. However, the absence of a substrate that is suitable for both technologically developed distributed Bragg reflectors (DBRs) and quantum well active regions has hindered the development of these devices. Several groups have attempted to overcome mirror limitations on InP substrates by examining AlGaAsSb-based DBRs. The high-index contrast of these DBRs leads to a lower penetration depth than that seen in traditional InGaAsP-based DBRs, which implies a lower optical loss in the structure. However, only optically-pumped VCSELs using such DBRs have been have been demonstrated.  DESCRIPTION: Scientists at the University of California have developed a single-growth, room temperature, electrically pumped 1.55 micrometer VCSEL. (more...)

Vertical-cavity surface-emitting lasers (VCSELs) are a new class of semiconductor lasers that are used in many optoelectronic applications. VCSELs have optical cavities that are perpendicular to substrate, as opposed to conventional edge-emitting lasers that emit light in a direction parallel to the semiconductor substrates. As a result, VCSELs emit optical radiation in a direction perpendicular to the substrate, which leads to various performance and application-adaptable improvements. Although both short and long wavelength VCSELs have provided solutions for many evolving optical applications, certain drawbacks exist, such as the need to electrically pump and conduct heat through the multilayer mirror stacks. In addition, the mirror stacks themselves have demonstrated limited thermal conductivity and excessive optical loss. Double-intracavity contacted VCSELs minimize or overcome these complications. (more...)

Vertical-cavity surface-emitting lasers (VCSELs) have demonstrated great promise as low-cost components in high-speed transceivers. Although they have been successful for shorter wavelength (850nm) systems, problems with excessive resistance and temperatures have limited the capabilities of these lasers in systems requiring wavelengths of 1.55 micrometers. (more...)

The vertical-cavity surface-emitting laser (VCSEL) is a semiconductor laser diode for long wavelengths that is becoming a popular choice for high-performance components for optical fiber networks. The VCSEL emits a laser beam vertically from the top surface of a wafer and is quickly replacing the conventional edge-emitting semiconductor lasers. Several advantages VCSELS have over edge-emitters include: VCSELs can be tested at several stages throughout the production process unlike edge-emitters, the VCSEL structure can be integrated in two-dimensional array configurations, several thousand VCSELs can be produced on a single GaAs wafer, and the yield of VCSEL production is much more controllable all of which leads to higher performance at lower cost. Other current applications for VCSELs include analog broadband signal transmission, absorption spectroscopy, and any number of fiber optic communication devices. (more...)