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MichaelPage - 16:46, Tuesday 15 June 2021 (2577)Get code to link to this report
Comment to OPO nonlinear gain revisited (Click here to view original report: 2569)

I recorded the thermistor (temperature) values that I used for the OPO nonlinear gain measurement.

Initially I searched in increments of +/- 0.01 kOhm on the thermistor, and then checked a bit within the optimal range. Perhaps there is further room for optimisation when zooming in on the oscilloscope though. At 100 mV/div ranges on the oscilloscope, the difference in voltage for thermistor change under 0.01 kOhm was hard to distinguish.

In the table I give the temperature, oscilloscope reading as well as the range value on the power meter - using a range of 1.6 mW on the power meter gives 10x more voltage on the oscilloscope than a range of 16 mW.

green power [mW] 0 10 15 20 25 30 35 40 50 60
MZ offset   3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.7 4.9

Amplification reading [mV] (power meter range [mW])

456 (1.6) 1140 (1.6) 1710 (1.6) 234 (16) 308 (16) 408 (16) 578 (16) 816 (16)    
De-amplification reading [mV] (power meter range [mW]) 456 (1.6) 240 (1.6) 216 (1.6) 192 (1.6) 178 (1.6) 166 (1.6) 160 (1.6) 152 (1.6)    
Thermistor value [kOhm] 7.137 7.147 7.165 7.173 7.185 7.196 7.203 7.215 7.215 7.225
p pol PLL frequency [MHz] 190 180 195 190 200 205 200 205 185 185
Nonlinear gain 1 2.5 3.8 5.1 6.8 8.9 12.7 17.9