University of Central Florida Research Foundation Inc

Oleg Efimov

Leonid B Glebov

Vadim Smirnov

Larissa Glebova

This disclosure relates to a laser communication system which allows changing the direction of reception and transmission without external manipulation of the system container. The basic unit of the system is a narrow-band transmitting-receiving telescope apparatus which includes a rotating diffraction grating and an independently rotating stage with mounted combination of photodetector for reception and laser for transmission and a focusing system concentrating the beam reflected from the grating onto the photodetector of the combination or sending a beam from laser of the combination onto the grating. The selection of definite angles for signal transmission-reception is realized by corresponding rotation of grating and rotating stage to the proper angles. The apparatus is intended for spectrally selective transmitting or receiving of optical radiation. The main advantages of this apparatus are compactness and its ability to receive and/or transmit the light with definite wavelength from/to an arbitrary direction without changing of the physical articulation of apparatus as whole.

Narrow band transmitting-receiving telescope system

Novel volume holographic elements were made from Bragg diffractive gratings in photo-thermo-refractive (PTR) glass with absolute diffraction efficiency ranging from greater than approximately 50% up to greater than approximately 93% and total losses below 5%. Both transmitting and reflecting volume diffractive elements were done from PTR glasses because of high spatial resolution enabling recording spatial frequencies up to 10000 mm . The use of such diffractive elements as angular selector, spatial filter, attenuator, switcher, modulator, beam splitter, beam sampler, beam deflectors controlled by positioning of grating matrix, by a small-angle master deflector or by spectral scanning, selector of particular wavelengths (notch filter, add/drop element, spectral shape former (gain equalizer), spectral sensor (wavelength meter/wavelocker), angular sensor (pointing locker), Bragg spectrometer (spectral analyzer), transversal and longitudinal mode selector in laser resonator were described. Combinations of those elements in the same volume are available too.

High efficiency volume diffractive elements in photo-thermo-refractive glass

A novel process is proposed for the volume diffractive element (Bragg grating) fabrication in photosensitive silicate glasses doped with silver, cerium, fluorine, and bromine. The process employs a photo-thermo-refractive (PTR) glass of high purity exposed to ultraviolet (UV) radiation of a He&mdash;Cd laser at 325 nm followed by thermal development at temperatures from 480&deg; C. to 580&deg; C., preferably at 520&deg; C., from several minutes to several hours. Absolute diffraction efficiency up to 95% was observed for 1 mm thick gratings. Maximum spatial frequency recorded in PTR glass was about of 10,000 mm . No decreasing of diffraction efficiency were detected at low spatial frequencies. Original glasses were transparent (absorption coefficient less than 1 cm ) from 350 to 4100 nm. Induced losses in exposed and developed glass decreased from 0.3 to 0.03 cm between 400 and 700 nm, respectively, and did not exceed 0.01-0.02 cm in the infrared (IR) region from 700 to 2500 nm.

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Orlando, FL, United States of America

Oleg Efimov