We are still trying to nail down our non-linear gain measurement. Here's a comparison between two methods:

1) MIT method:

nlg = ((sqrt(pMax/pMin) + 1)/2)^2

2) ANU method:

nlg = pMax/pUnamp

pUnamp is seed transmission measured outside nlg region as I scan the OPO cavity (temperature set to ~51C, green blocked). Which is an unamplified seed power.

I took nlg measurement with data from StripTool and oscilloscope. The result are consistent within 10% between the two methods and two devices. 

Pump input to coupler: 20mW

Pump reflected (OPO off resonance): 2.7 mW

Seed input to coupler: 1 mW

StripTool (IR trans PD): max = 0.0063 mW, min = 0.0019 mW, DN = -6.8e-5 mW

Scope (IR trans PD): max = 142 mV, min = 47.6mV, DN 8mV

Seed trans unamplified: StripTool = 0.003 mW, Scope = 76.4 mV