Cheryl, Rodica

Yesterday we measured isolation and transmission of the H1 Faraday isolator with the 4 mm thick DKDP installed. In the first run we measured while ramping up the power to ~140 W and optimizing the HWP and DKDP, the secon set was measured 3 hours later after the system cooled down slightly but without any additional optimization, and the third set was measured immediatelly after the second run, while ramping the power down.

Transmission is ~97%, forward extinction is ~ 25 dB and isolation stays above 25 dB at maximum power. Graphs are attached. The isolation is limited by the amount of stray light from ghost beams from the FI crystals that are dirrected toward the same power meter.