Eli notebook

ECDL Tuning

8/5/15

I was able to achieve 20-25GHz tuning range with the 785 nm diode with a ratio of about -.1mA/V. The best scans were with the current at a setpoint between 80-100mA. Through each scan, the current dropped about 15 mA which led to a drop in output power of about 8-9mW. With the 1065nm diode, I got the tuning rates for the piezo to be .14GHz/V. The current tuned extremely slow with about .0134GHz/mA. Using these rates, the ratio for the current and piezo should be 10.45mA/V.

7/16/15

I tuned the laser by varying the current from 35mA to 120mA and kept the piezo at 2V for one scan and 35V for another. The 2V scan gave a little cleaner data and both gave nearly the same tuning rate of about -1.5 GHz/mA. The rate seemed to increase at higher currents. This tuning rate along with the piezo tuning rate implies that the piezo and current should be tuned with a ratio of about -.107 mA/V which is quite low compared to what I've been reading.

7/14/15

Tuned a 785nm laser by keeping current fixed at 68.5mA and ramping the grating piezo from 0 to 150V. Got a pretty decent plot of frequency vs piezo voltage with clear mode hops. Decreasing the voltage from 150V to 0V yielded a messier plot with more random mode hops. In all, the laser tunes with a rate of about .16 GHz/V.

To get an idea of how the laser tunes with current I tried eliminating the external cavity by removing the grating but the laser was pretty unstable this way and wouldn't stay single mode even while keeping the current fixed. So I attached the grating and I tried to tune the laser by keeping the piezo at a fixed voltage while varying the current. I'm now trying to find a piezo setting that allows a workable range of single mode while changing the current so I can get get some good data. I'm also unsure if having the external cavity while varying the current changes the tuning rate as opposed to tuning the laser diode without the grating.