Frequency Stabilization of a Semiconductor Laser under Direct FSK Modulation: The Modulation Method and Evaluation of Stability

摘要

The frequency stability of a semiconductor laser de- teriorated under direct frequency shift keying (FSK) when stabilization depended entirely upon an external frequency reference. Therefore, the PEAK method was devised for the purpose of improving frequency stability. This method requires two distinct frequency compo- Nents and, therefore, will not work effectively in a commu- Nication system that produces a succession of identical Frequencies, as does the FSK method on occasion.