Yao-Chin and Yuhang
When IRMC locking and only LO light hit into homodyne detector, we aligned LO light to arrive dc balance signal of homodyne shown in fig 1 and measured shot noise using analyzer (Aglient 35670A). Using low frequency, which range from 125mHz to 200Hz, random noise from analyzer source sent to high voltage amplifier (Gain: x15) of IR phase shifter(CC2). With different Vpp values of random noise (its spectrum shown in fig 2), we measured the RF spectrums of homodyne detector. Below 100mV Vpp, the spectrums are similar from 20Hz to 200Hz range shown in fig 3. The magnitude value of shot noise increased when above 500mV Vpp of random noise.
|
Vpp of random noise (mV) |
Average value (dB) |
| 0 | -133.40 |
| 5 | -133.34 |
| 10 | -133.40 |
| 50 | -133.34 |
| 100 | -133.29 |
| 500 | -128.40 |
| 1000 | -120.98 |
Note: We average spectrum magnitude value from 20Hz to 200Hz.
