Development of a high-power wavelength-division multiplexing (HP-WDM) module for high-speed space optical communication

Free-space optical communication is becoming essential for applications requiring high-throughput space links, such as data transmission for Earth observation satellites, inter-satellite links, cislunar space networks, and deep space exploration. One method for enhancing the communication capacity is to increase the transmission power. However, it is difficult for a single amplifier to provide high output power while satisfying the requirements for space components (e.g., space-environmental resistance and performance reliability). To overcome these issues, we propose a high-power wavelength-division multiplexing (HP-WDM) scheme. This paper describes an experimental evaluation of a prototype HP-WDM module under a thermal vacuum environment. Our results indicate that a total output power of 10W can be achieved by multiplexing two 5-W optical beams in the conventional band. To ensure stable multiplexing performance, we address the key thermal effects in the HP-WDM module, including the optical axis misalignment between the two high-power beams.