Some Observations:

• Temperature of laser (in kOhms) North: 10.056, South: 10.097
• Power (in mW) North: 7.02, South: 7.26
• Beat frequency: ~20 MHz, -50 dBm
• After changing south laser temperature to 10.985 kOhms, the beat moved to 40 MHz, 4 dBm (!)

Some information:

• Ring cavity made of :

Ma R~90%, Mb R>96%, Mc R>96% RoC 1m Coastline Optics CO-SAP-1000-250-1.0MP

Ma -> Mb -> Mc -> Ma

• Photo-diode: PDA20CS

Updates:

• Got the beam in the triangular cavity to more or less align, i.e., overlap with itself as checked on one side of the triangle
• I hooked up the transmission PD in the transmission path of Mc
  • At different temperature settings, blocking the incoming beam (Mb -> Mc) resulted in the power becoming minimum and blocking the beam (Mc -> Ma) resulted in some variable fraction of the the nominal power which I take to be a sign of interference (?)
  • I moved around the temperature using the setpoint knob, but since the movement of the knob was nonlinear which along with a nonlinear change in power and frequency (with temperature) made it hard for me to figure out exactly what was happening in the limited time I spent on this so far

Next steps:

• Going to explore the laser lock on the Moku:Lab for a while, after which I'll decide whether or not to continue with that or move to mixers + PDH servo box