[Aritomi, Yuhang]

Since we receive message from Henning, the voltage from pin 1 to 3 to 5 should be from -19 to 0 to 19V. So it means we should swap the connector. After do that we can see the signal on oscilloscope and its value is reasonable. Also the current coming out from power supply becomes not zero. As shown in the last attached figure. So we can say homodyne works well now.

After that, I measured again the dark noise of homo-dyne.

Firstly, I measured the electronic noise while SR560 is set gain as 1000(means 60dB). The result is shown in the first attached figure.

Then I measured the signal from homo-dyne whlie no light going inside homo-dyne. The result indicates the dark noise of homo-dyne is -93.2-60 = -153.2 dBV/rtHz. The result from Henning is -156.2dBVrms/rtHz(shown in attached figure 3). And since there is relationship Vrms = V/sqrt(2). This factor sqrt(2) is exactly 3dB difference. This means our measurement perfectly matches Henning's measurement.