Study of Link Gain and Locking Range in Hybrid Mode-Locked Laser-Based MillimeteR-Wave Radio-Over-Fiber System

An investigation of hybrid mode-locked lasers is performed to better understand their link gain and locking range behavior under external RF injection for their use in millimeter wave radio-over-fiber systems. The dependence of 40-GHz link gain on different parameters is initially identified and then the three main parameters of gain and saturable absorber section biases and external RF injection signal power are studied in detail. It is found that higher injection power leads to lower link gain ranging from -19dB to -22dB, whereas lower injection power gives higher link gain ranging from -10dB to -19.9dB. This article also reports a hybrid mode-locking range of 90.97 MHz which is the widest reported so far for the technique used here. (C) 2013 Wiley Periodicals, Inc.