Here are some calculations regarding the DC control of the frequency of the Thorlabs ULN15TK laser in B102. The measured value of the Hz/V laser tuning coefficient disagrees with the value calculated from the datasheet by roughly a factor of 2.
First, the laser frequency was swept with a 2Vpk-pk triangle wave at 10Hz. Two resonance peaks were identified to be 30ms apart. We want to convert this time difference into a voltage difference using the properties of the tringle wave.
30ms*2V*2*10Hz = 30ms*40V/s = 1.2V
The free spectral range of the cavity, measured in Hz is the inverse of the travel time in the cavity, or c/L
FSR = 3e8/2.4 = 125MHz
Together these values give 104MHz/V
We should also be able to calculate this value (Hz/V) using only the datasheet of the laser.
Under the specs tab, it is reported that the DC voltage to current conversion rate is 2 mA/V, and the current tuning coefficient is 0.25pm/mA
This gives us 0.5pm/V tuning. We now convert this to frequency.
0.5pm/V*(3e8m/s)/(1550nm)^2 = 62MHz/V