Multi-beam optical injection locking in Fabry-Pérot laser diodes

Abstract

Optical injection locking has numerous applications including direct modulation bandwidth enhancement, all-optical function device (such as the all-optical wavelength convertor, all-optical memory, time recovery devices, etc), all-optical network, wavelength division multiplexing passive optical network (WDM-PON) and microwave signal generation. These applications of optical injection locking have attracted experimental and theoretical researches over forty years. These research mainly focused on single beam injection locking. Only few research have considered multi-beam optical injection locking, and these few research are almost all experimental studies. However, most applications of optical injection locking are based on multi-beam optical injection locking, in which two or more light beams are injected into an Fabry-Perot laser diode. In this work, we focus on theoretical study of the multi-beam optical injection locking. Firstly, a self-consistent multimode rate equation model is derived and applied to the simulation of 10 Gb/s all-optical header processing and all-optical packet switching. Besides the simple rate equation model, the transmission line laser model packaged in the commercially available software produced by the VPITM is also used. Because of the short length of the Fabry-Perot cavity, the efficiency of simulation in the transmission line laser model is high. By using this transmission line laser model, we study the multi-beam optical injection locking with bias current modulation of the Fabry-Perot laser diode which can be used for high frequency microwave signal generation. The main features in this new proposed method are studied in details, including criteria of the sideband injection locking, asymmetric sideband injection locking ranges and effect of bias current modulation format on sidebands injection locking ranges. With this proposed method, microwave signal with frequency N times the modulation frequency of the bias current of the Fabry-Perot laser diode can be generated, where N is the order of the modulated harmonic sidebands. Sideband injection locking range, frequency tunable range of the generated RF signal, as well as maximum RF signal output power are also investigated. Multi-beam optical injection locking from external injections is then studied, where these external injection lights come from different independent lasers. We study two beams optical injection locking numerically. It is found that the behavior of the injection locking when two beams are injected into the same cavity mode of the Fabry-Perot laser diode is quite different from the case when the two external injection beams are injected into different cavity modes. This new feature might be useful for other modulation format such as the frequency shift keying in the applications of multi-beam optical injection locking.