The control box for The Rock has three switches for relative intensity noise suppression (RIN) On/Off, Laser On/Off, and constant current (ACC) versus constant power (ACP). There are two LEDs to indicate the presence of a 2nd cavity mode (red) and temperature stability (green). The sequence for turning on The Rock is:
- - Laser is off from the previous day, switches should be set to: RIN Off, Laser Off, ACC
- - Switch Laser to On and wait for the grating temperatures to stabilize. After ~20 minutes the green LED will light, and hopefully the red LED will be off
- - Switch to RIN On to stabilize power (used to also switch to APC, but this was seen to add noise - now leave on ACC)
The output of The Rock is ~150mW. The control box should be connected to a computer via RS232 so that the provided software can be used for more advanced control.
If the red LED is still on when the temperature stabilizes, the 'Optimization Process' may be run. This will adjust a piezo actuator attached to the cavity to move laser operaration into a single-mode region of the cavity. This process is run from the provided 'Fiber Laser Control Panel' software.
The Rock has a 30GHz wavelength tuning range, or about 0.1nm around 1053nm. This is most easily performed via a slider bar in the provided software. After adjusting the wavelength the laser will need more time (~10min) to stabilize grating temperature, after which the optimization process should be run. Tuning the wavelength without running the optimization process resulted in some hysteresis between the slider and measured wavelength.
The measured wavelength (using the Wavemeter) was slightly different from the slider setting, as shown:
The lowest and highest accessible wavelengths (as measured) are 1053.451nm and 1053.566nm.
By switching to manual control of the grating temperature (press the Wavelength Tuning 'On' button so that it is grey instead of yellow), one can access a larger range of wavelengths:
For manual tuning, the temperature should not exceed 80 degrees Celsius. This extended range should allow us to access the magic wavelengths for the 4s-5p transition.