Implementation of optical logic gates and combinational blocks with multi-input injection locking in external cavity single-mode Fabry-Perot laser diodes

Abstract

A novel approach of multi-input injection locking (MIL) through power management of input beams for the suppression of dominant modes in single mode Fabry-Perot laser diode (SMFP-LD) is realized and demonstrat-ed. Single-input injection locking (SIL), MIL and supporting beam injection locking (SBIL) phenomenon are demonstrated using the proper power management scheme. With this novel approach of power management, multi-function logic gates and digital combinational circuits utilizing MIL and SBIL, and all-optical ON/OFF switch utilizing SIL, are demonstrated at the input data rate of 10 Gbps. FP-LDs, used for the analysis of SIL, MIL and SBIL are specially designed in our laboratory, have the self-locked mode and exhibit the inherent multi-mode (MM) characteristics. As MMFP-LDs, SMFP-LDs show dif-ferent responses to the input beams injected to the side modes. When the external beam is injected close to any one of the longitudinal mode of the solitary FP-LD, the single mode operation at the self-locking dominant mode collapses. The injection locking on the selected mode by the external beam causes the change in carrier density which results red shift of cavity modes and hence the mode matching condition of the coupled cavities is distributed. The suppression of the dominant mode depends on the wavelength detuning of the SMFP-LDs and the power of the injected external beams. The wavelength detuning and required input beam power for injection locking are proportional to each other. Hence, the suppression of the dominant mode can be controlled with changing any of the parameter (either power of input beam or wavelength detuning), making another as a constant value. This technique facilitates the proposed SIL, MIL and SBIL principles. Based on these proposed principles of SIL, MIL and SBIL for suppressing the dominant mode of the SMFP-LD, simple, cost effective, and power effective ON/OFF switch; various logic gates and digital combinational circuits are demonst...