All-semiconductor continuous-wave volumetric ranging for spaceborne differential absorption lidar

State-of-the-art semiconductor lasers can deliver average power, linewidth, and beam quality suitable for supporting differential absorption (DIAL) instruments that are competitive with fiber and solid-state lasers. An all-semiconductor transmitter architecture can enable a drastic reduction in size, weight, and power consumption (SWaP) of the instrument, while allowing for beneficial wavelength agility. Crucially, this reduction in SWaP can enable the implementation of compact airborne and spaceborne profiling DIAL instruments with high power output, while the broad spectral coverage of semiconductor laser technology allows to adapt and tune the transmitter design across a variety of operating scenarios. In this work, we present the first demonstration of volumetric ranging based on an all-semiconductor intensity-modulated CW (IMCW) transmitter. For this proof-of-concept demonstration, we used Rayleigh backscattering in fiber to emulate the atmospheric backscattering return echo. The range-resolved profile is reconstructed using matched filtering of the return echo, a technique widely adopted in CW radar. Finally, we present a theoretical analysis grounded in CW radar theory, showing excellent agreement with the results measured across a wide range of transmitted waveforms and return target configurations.