All-optical wavelength converters and logic gates by gain modulation in fabry-perot laser diodes

Abstract

In this thesis, a novel technology of all-optical wavelength conversion and all-optical logic gates is proposed and demonstrated by using the injection locking and gain modulation in Fabry-Perot laser diode (FP-LD). An FP-LD shows different responses to external optical injections depending on injected beam’s spectral location. When a transverse electric (TE) mode optical beam is injected near one of longitudinal lasing modes of the FP-LD, the laser shows typical injection locking with a gain. The output of the injection-locked FP-LD shows several interesting features, including the red-shift of the cavity modes of the laser and the asymmetric injection-locking curve. This asymmetric injection locking behavior shows that, to get an injection locking state, the external beam should be injected in a certain locking range. If the external beam is out of the locking range, the bean cannot lock the FP-LD and the external beam does not show any power gain. Using this injection locking characteristic, one external beam (probe) power can be optically controlled by another external beam (pump) with certain conditions. The gain variation of the probe beam power by the injection of pump beam is referred to as gain modulation. This gain modulation of an injection-locked FP-LD is applied for realizing simple and cost-effective all-optical wavelength converter and all-optical logic gate in this thesis. The operations are carried out at a bit rate of 10 Gb/s. Different configurations of wavelength converters are experimentally demonstrated. To realize multi wavelength conversion with multicasting functions, a $1\times4$ and $4\times4$ wavelength conversions are demonstrated. To realize the capability of wavelength up-conversion and wavelength down-conversion, a $1\times4$ wavelength up and a $1\times4$ wavelength down converters are demonstrated. To see the wide range wavelength conversion capability of this scheme, the probe signals were set to different spectral loc...