High Efficient Volume Holographic Elements for High Power Lasers

In Phase I, LPTI proved f the concept of high efficiency narrow-band mirror in photo-thermo-refractive glass (PTRG) for high power Nd:YAG laser. In Phase II, a number of photo-thermo-refractive diffractive optical elements (PTR HOEs) including both reflecting and transmitting volume gratings, will be fabricated for different types of high power lasers, and high power beam control will be demonstrated. A technology of PTRG blanks up to 25 mm,e25 mm,e5 mm with the refractive index fluctuations less than 2,e10-5 (20 ppm), an induced refractive index greater than 1000 ppm, and a photosensitivity greater than 1 ppm mJ 1 cm2 will be developed. A setup for the recording of PTR HOEs with 12 mm diameter and variations of diffraction across the aperture less than 10% will be designed, constructed, and tested. The effect of glass technology and holographic processing on insertion losses and laser-induced damage will be studied. The narrow-band diffractive mirrors and deflectors for different types of high power lasers will be made with the following parameters: diameter up to 12 mm, diffraction efficiency greater that 90 %, thermal stability up to 400¿XC, laser stability in CW mode up to 100 kW/cm2, for 10 ns pulses up to 10 J/cm2.