Improved laser capability using III-Nitride VCSELs as the illumination source for sensing applications of a fluorescent sample.
Various light sources have been developed for use in fluorescent sensors, such as LEDs, xenon arc lamps, mercury-vapor lamps, halogen bulbs, and lasers. Aside from the lasers, these light sources require filters and other optical modulators to obtain the desired wavelength in a small enough spot size for probing. On the other hand, lasers provide coherent and relatively small spot size light sources with narrow spectral widths which may not require the additional elements. Vertical cavity surface emitting lasers (VCSELs) have a number of qualities that make them desirable: circular beam profile, small spot size, low threshold current, and 2D array capabilities. A VCSEL can be positioned such that the light output illuminates a certain portion of the sample. New technology is continuing to improve VCSELS.
Researchers at the University of California, Santa Barbara improved laser capability by using III-Nitride VCSELs as the illumination source for sensing applications of a fluorescent sample. The incident beams are absorbed by the sample, which fluoresces, and the remaining VCSEL light is filtered out before a detector. The circular beam profile allows for focusing of the beam to even smaller spot sizes, potentially increasing resolution. Applications include, but are not limited to, optogenetic biosensors. This technology also enables stimulation of multiple points of a sample via a VCSEL array. The surface emitting lasers have low threshold currents, which means that the array could be battery powered, making them easier to transport.
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