LIGO Document T2500346-v1
- The current aLIGO squeezer cannot meet the A# requirement of 10dB of realized squeezing, operational stability, and duty cycle. One of the main causes of the degradation of the squeezer over time is gray tracking in the periodically poled potassium titanyl phosphate PPKTP crystals used in both SHG and OPO. Gray tracking is a well-known, but not well understood, phenomenon and has been shown to cause losses in both 532 nm and 1064
The existence of T i3+ impurities within the crystal lattice is believed to create a trapped energy state inside the band gap between the covalent and the conduction bands. Another cause associated with PPKTP crystals is GRIIRA (Green-Induced Infrared Absorption), where infrared loss occurs in the presence of green light.
DCC Version 3.5.2, contact
DCC Help