Phase noise reduction of a semiconductor laser in a composite optical phase-locked loop

Amnon Yariv California Institute of Technology Department of Applied Physics and California Institute of Technology Department of Electrical Engineering 1200 East California Boulevard 128-95 Pasadena, California 91125 Abstract. The bandwidth and residual phase noise of optical phaselocked loops (OPLLs) using semiconductor lasers are typically constrained by the nonuniform frequency modulation response of the laser, limiting their usefulness in a number of applications. It is shown in this work that additional feedback control using an optical phase modulator improves the coherence between the master and slave lasers in the OPLL by achieving bandwidths determined only by the propagation delay in the loop. A phase noise reduction by more than a factor of two is demonstrated in a proof-of-concept experiment using a commercial distributed feedback semiconductor laser. C © 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3518077]