Abstract

Optical frequency modulation (FM) or phase modulation (PM) noise determines performance limitations in coherent and incoherent optical communication systems. To date techniques for FM noise reduction have been limited to electronic and optical feedback. However, with electronic feedback, the maximum FM suppression frequency (~200 MHz,¹) is limited by the feedback loop delay time. In the case of optical feedback, the laser linewidth and oscillation mode stability are very sensitive to the feedback phase. Both feedback techniques require access to the source laser and usually enhance FM noise at high frequencies, which can deteriorate the transmission performance in coherent systems.

© 1992 Optical Society of America