Frequency Control of Microchip Lasers

The idea of coherent optical frequency division multiplexing gives larger possibilities and new qualities compare to IM-DD (Intensity Modulation – Direct Detection) systems. These optical FM systems require stable and controllable offset lasers. The control systems of laser frequency stabilization use a few mechanisms of tuning: thermal, piezoelectric and electrooptic. Thermal tuning is a very slow process but it enables to tune the resonator laser even over few tens of microns. Piezoelectric tuning is usually limited to a few of microns and in the frequency band of tens of Hz. The electrooptic phase modulator inserted inside a laser resonator gives the fastest tuning in the band of few tens of kHz. Two kinds of microchip lasers Nd: YVO4 and Nd:YAG with LiNbO3 modulators are presented.