Kiwamu, Alexa

Today we looked at the demod phases for the REFLAIR RFPDs. The result was inconclusive. We excited PRM_M3_LOCK_L at 3.25Hz with an amplitude of 10000cts. We then examined the magnitude of transfer function of the I/Q error signals to this excitation at 1W, 5W, 7W, and 10W incident laser power. The data was taken with RELFAIR_A_RF45 at -135deg, RELFAIR_A_RF9 at 93deg, REFLAIR_B_RF27 at 107.8deg, and RELFAIR_B_135 at -30 deg following our nominal configuration. Attached show the magnitude vs power for the 1f and 3f signals, along with a linear fit. RELFAIR_A_RF9 behaves as expected with a linear reponse. During the measurement, REFLAIR_A_RF45 was not very coherent with the excitation, which explains why 45Q's response does not look very good. REFLAIR_B_RF27 looks fine as well; but RELFAIR_B_RF135 does not look right; it appears I might have missed a sign flip in the TF. But no major red flags...