Testbed for Modulating Retroreflectors Enabled Passive Optical Communications

A “laserless” optical communication transceiver(also known as a “modulating retroreflector”) uses a wide-angleretroreflector and surface-normal electro-absorptive quantumwell modulators to efficiently encode information onto theoptical beam, which is reflected along the same path ofincidence. This is particularly attractive to planetary missionconcepts using a highly asymmetric resource-allocatedarchitecture and examples include surface missions to theMoon, Mars, and other planetary destinations. A key challengeis the wide temperature range that the transceiver needs tooperate without high-power active temperature control. This isparticularly challenging for ground prototyping work when thetemperature is as low as 100K (lunar night) in the ambientlaboratory environment. We designed and constructed alaboratory testbed that can simulate the required operatingtemperature range for the passive optical communicationtransceiver including the optics, quantum-well modulator, andnecessary electronics. The testbed also includes a design that canwork with both continuous-wave lasers and optical frequencycombs (pulsed lasers) as the interrogating light sources.