Large Format Narrow Band High Throughput Optical Filters for 0.5-2.7µ

One of the most efficient ways to create narrow band filter is the use of reflective Bragg gratings or which allow increasing of efficiency and decreasing of weight compare to conventional technologies. OptiGrate have proved the concept of high efficiency narrow-band mirrors in photo-thermo-refractive glass (PTR) glass for high power laser applications based on a unique technology for phase hologram recording. Bragg mirrors with more then 90% of diffraction efficiency and spectral bandwidth of 80 pm have been demonstrated. OptiGrate proposes development of reflecting Bragg gratings in PTR glass with spectral selectivity less than 0.1 nm and clear aperture up to 25x25 mm. To achieve spectral resolution of reflective Bragg grating below 0.1 nm, several problems should be solved which are uniformity of refractive index and photosensitivity of PTR glass across the aperture of 25 mm in a glass blank with thickness exceeding 10 mm. The unique hybrid filter based on reflective Bragg gratings and Fabry-Perot etalon will results in unprecedented spectral bandwidth combined with efficiency of more then 90%. Successful completion of these tasks would results in technology of narrow band filters with high diffraction efficiency for visible and near IR region of spectrum. A number of prototypes for wavelengths of NASA's interest will be delivered.