A fibre-based deep space optical data terminal incorporates a seed laser, amplitude, frequency and / or phase modulator, optical amplifier and free-space beam forming optic. Provision is also made for coarse and fine pointing. For little additional Size Weigh and Power (SWaP), the architecture can be extended to that of a coherent Laser Imager Distance and Ranging LIDAR. Unlike conventional direct detection and photon counting schemes, it is relatively straightforward with coherent LIDAR to achieve quantum limited detection performance with unsophisticated detectors.

Communication links between GNSS satellites are required if the constellation shall operate for an extended time without ground contact. Under such circumstances, jamming resistance is considered a critical requirement and optical links can provide the ultimate protection from ground-to-space jamming. At the same time, low cost, high reliability and small size, mass and power are important to be implemented on a GNSS constellation. The activity shall review the requirements on intersatellite links based on the GNSS architecture.

Communication links between GNSS satellites are required if the constellation shall operate for an extended time without ground contact. Under such circumstances, jamming resistance is considered a critical requirement and optical links can provide the ultimate protection from ground-to-space jamming. At the same time, low cost, high reliability and small size, mass and power are important to be implemented on a GNSS constellation. The activity shall review the requirements on intersatellite links based on the GNSS architecture.

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The starting point of the activities was the matching performance of a single element InGaAsSb detector, grown on a low cost GaAs substrate, reported by the University of Lancaster. GaAs substrates are low cost and available in large areas, making high pixel count arrays feasible, nevertheless resulting in a slightly lower InGaAsSb material quality. GaSb has been also used as second substrate material candidate: indeed it is easier to grow high quality layers on GaSb even though the bandgap of GaSb prevents to use it in 2D focal planes.

EChO requires MCT detectors with low readout noise and dark current, high quantum efficiency (over 0.4-2.5 um) and a low operational temperature (down to 40K). The LFSA required performances are mostly in line or less demanding than ECHO needs, in particular for the readout noise and overall ROIC performances. However, wavelength range and operational temperature need extension.

Recent developments in optical fabrication, detector technologies and spectral filter allow very compact telescopes and spectrometers designs, although less

Background and justification: