YuhangZhao - 13:21, Thursday 10 October 2019 (1728)
PDH signal comparison from FC reflection(qubig PD and NIKHEF PD)
To compare the signal from qubig PD and NIKHEF PD, I did this check. (There was already a check reported in the entry 1670)
The situation of green power is
| green power on qubig PD | 210uW |
| green power on NIKHEF PD | 1.2mW |
The electronics after PD is
| 1. qubig PD | then goes to RFamplifier(14dB) | then goes to demodulator (used for FC locking, from the mini-circuit company) | then detect on the oscilloscope | ---------- |
| 2. NIKHEF PD (I put all light on the first quarter of this PD on purpose) | then I take the RF signal from the first quarter | then goes to RF amplifier(14dB) | then goes to demodulator (used for FC locking, from the mini-circuit company) | then detect on the oscilloscope |
The result of PDH signal is
| qubig PD pk-pk | 164mV | attached Fig.1 |
| NIKHEF PD pk-pk | 14.8mV | attached Fig.2 |
Note: If I put these signal to NIKHEF demodulator is qubig PD pk-pk 35mV(reduce by a factor of ~5), NIKHEF PD pk-pk 10mV(reduce by a factor ~1.5).
Images attached to this report
