Cascaded Directional Coupler-Based Triplexer Working on Spectroscopically Relevant Wavelengths for Multiple Gas Detection

In this article, we present experimental and simulation results of a novel high-performance cascaded directional coupler-based triplexer. The device is designed to combine the wavelengths of 1530 nm, 1653.7 nm, and 2003 nm for use in spectroscopy systems targeting the detection of ammonia, methane, and carbon dioxide gases, respectively. The triplexer’s functions focus on enhancing the coupling efficiency and selectivity, while facilitating the on-chip integration of diode lasers. The experimental results demonstrate that the coupling efficiency is 82%, 73%, and 91% for the respective wavelengths of 1530 nm, 1653.7 nm, and 2003 nm. The results highlight the triplexer’s capability as a multifunctional beam combiner and an adaptable power source, essential for advanced gas sensing techniques and integrated couplers.