Novel coding schemes for dual wavelength quantum cascade laser‐based free space optical links

Abstract

Dual wavelength quantum cascade lasers (DW‐QCLs) are a type of semiconductor laser that can emit two different wavelengths of light simultaneously. They are constructed using quantum cascade structures, consisting of multiple layers of semiconductor materials carefully engineered to produce the desired wavelengths of light. This research article reports the numerical simulation and evaluation of the maximum capacity of free space optical (FSO) link employing novel coding schemes for DW‐QCL‐based pulsed optical transmitters. A 48‐stage DW‐QCL emitting at 10.5 and 8.9 μm wavelengths and a Quantum‐Well based Infrared Photodetector based receiver are considered for the study. The performance of the link is analyzed under short pulse transmission from the device at both wavelengths for various scenarios. Optical pulses are obtained either at a single wavelength or two different wavelengths by proper choice of electrical input current amplitude. This feature enables the implementation of four different coding schemes. Among the various coding approaches proposed, the scheme, which operates on symbols, performs the best, providing a maximum link length of 1700m, for a BER of 10−9.