Sn_(2)P_(2)S_(6) crystals for fast near infrared photorefraction and phase conjugation

摘要

We investigate the photorefractive properties of Sn_(2)P_(2)S_(6) in the near infrared wave-length range. Conventional "yellow" and modified "brown" crystals are examined, which were grown by vapor-transport technique using respectively SnI_(4) and SnI_(2) as a transporter agent. We measured an increase of the photorefractive gain from 3 cm~(-1) in yellow samples to 18 cm~(-1) in brown samples at 780 nm. Self-pumped phase conjugation was studied in a ring cavity scheme. Using yellow sample phase conjugate reflectivity at 780 nm is about 55% and the response time in the order of 5 s at 20 mW. The phase-conjugate response in brown samples, however, is observed in only about 20 ms, which is two-orders of magnitude faster.