Theoretical And Experimental Study Of The Photo-thermo-refractive Glass And The Diffraction Characters Of Volume Grating

In recent years, the volume grating devices play an increasingly important role indifferent fields such as laser system design, three dimensional imaging, and opticalcommunication. The performances of holographic volume grating mainly depend onrecording materials. The volume gratings recorded in the photo-thermo-refractive(PTR) glass have excellent wavelength and angular selectivity, high diffractionefficiency, high damage threshold, low noise, low loss, etc. Therefore，the photo-thermo-refractive volume grating have been paid more attention and studying inrecent years owe to their special advantages.Research progress of the photo-thermo-refractive volume grating iscomprehensive reviewed in this paper. The holographic recording and diffractivecharacteristics of the photo-thermo-refractive glass are investigated theoretically andexperimentally. All the photo-thermo-refractive glass is manufactured in our lab.Theoretically, ultraviolet exposure and thermal development mechanism of thephoto-thermo-refractive volume grating are described. The theory of transmissionrecording and reflective readout is analyzed. Experimentally, absorption spectrums ofphoto-thermo-refractive glass before ultraviolet exposure and after exposure withthermal development are measured respectively, and the sensitive wavelength range ofthe material is discussed according to the measurement results. According to theprinciple of variable wavelength readout, optical setup is designed for the recordingand readout for transmission photo-thermo-refractive volume grating. The angularselectivity of the transmission photo-thermo-refractive volume grating after thermaldevelopment is measured, and stability of the recorded grating is monitored.The depth selectivity of the aperiodic grating is discussed theoretically aimingto the potential application in volume holographic imaging system. The diffractivecharacteristics of aperiodic volume holographic grating is analyzed by regarding it asan ensemble of locally planar gratings cooperating with Kogelnik coupled-wavetheory. The effects of two-beam recording angle on the depth selectivity of therecorded aperiodic grating are described based on the simulation results. Furthermore,the depth selectivity of volume gating in spherical reference volume holographicimaging system and planar reference volume holographic imaging system aresimulated respectively. All the results show that the depth selectivity in sphericalreference volume holographic imaging system is better than that of in planar referencevolume holographic imaging system.