“Loop Stabilized” Improved Transfer Cavity-Based Laser Frequency Stabilization

We describe an improved laser frequency stabilization technique that overcomes limitation of the conventional Transfer Cavity (TC) method by prohibiting frequency drift of the desired (working) laser arising due to change in differential optical path length of the Fabry-Perot (FP) cavity with respect to the reference laser. Unlike the TC where noise at each stage propagates and cascades to the working laser, in this novel “Loop Stabilized Transfer Cavity (LSTC)” technique, different stages like the reference and working lasers, FP cavity constitute a loop which is stabilized altogether rather than stabilizing the individual component. As a result, frequency of the working laser is restricted from drifting and overall noise is also reduced as compared to that in the TC. Theoretical and experimental results comparing both the techniques are presented here.