The PPCL590 is an integrated solution for locking the Pure Photonics PPCL700 tunable laser to a frequency reference. 

Using this compensates for the tunable laser longer term (1 sec +) wander and it stabilizes (narrows) the frequency variation on shorter terms (ms – sec). The dominant Gaussian noise of the tunable laser in the 1ms to 1sec range is thus significantly reduced.

The PPCL590 can be configured with an Acetylene gascell or a 50 GHz spaced high-finesse etalon. 

• the gascell provides absolute frequency accuracy and stability . It has absorption peaks in the 1522-1540nm range (only) and the linewidht narrowing will depend on the depth of the peak. RMS frequency values of as low as 300kHz are achieved for the best peaks
• The etalon provides regularly spaced peaks over the full C-band with a consistent peak shape (and hence consistent linewidth narrowing). RMS frequency down to 300kHz RMS are achieved for each peak. The etalon is however temperature dependent and will shift over temperature and time.