Fig. 4: Spaceborne application examples: PCM-integrated active devices for technology sub-systems in CubeSats.

a A constellation of CubeSats providing time-resolved spectroscopic imaging. Image credit: MIT/LL, NASA⁴⁵. b CubeSat Laser Infrared CrosslinK (CLICK) payloads for space-to-ground and crosslink communications. The fine steering mirror (FSM) steers the beams (976 nm Beacon laser/1550 nm transmitter laser) to dichroic mirrors in the respective optical systems⁴⁶. c SAGE-IV (Stratospheric Aerosol and Gas Experiment-IV) pathfinder multispectral LIDAR instrument, with a filter wheel consisting of eight bandpass filters and one opaque element. Each is designed to observe a target species such as aerosols and ozone⁴⁷. d NASA’s low-cost optical terminal (LCOT) free-space optical subsystem (FSOS), a ground terminal for space optical communications⁴⁸. This terminal consists of two sets of filter wheels and an FSM. e Reconfigurable planar optics for free-space optical communications: PCM-based beam steerers and highly pixelated “meta-correctors” can achieve a broad range of optical phase coverage, translating to large angular scanning and phase-correction ranges³⁸ (e, left). Packaged device consisting of the reconfigurable PCM-metasurface (middle, right) which deflects an incoming IR beam with output angle dependent on index of the PCM. f Tunable bandpass filter for spaceborne LIDAR: (f, left) The SAGE filter wheel may be replaced with a single element PCM tunable filter used to switch between different CWLs (i.e., different chemical absorption channels). Through an optical or electrical stimuli on the filter active area, PCM crystallinity is modified, and the resultant transmission response (λ_N) is spectrally shifted as demonstrated (right) by CO₂ gas sensing with GST-Fabry–Perot tunable bandpass filters⁴⁹.