Optical communication is becoming more prevalent in orbit due to the need for increased data throughput. Nanosatellites, which are satellites that typically weigh less than 10 kg, are also becoming more common due to lower launch costs that enable the rapid testing of technology in a space environment. Nanosatellites are cheaper to launch than their larger counterparts and may be a viable option for communicating beyond Earth’s orbit, but have strict Size,Weight, and Power (SWaP) requirements. The Miniature Optical Communication Transceiver (MOCT) is a compact optical transceiver designed to provide modest data rates to SWaP constrained platforms, like nanosatellites. This paper will cover the optical amplifier characterization and simulated performance of the MOCT amplifier design that produces 1 kW peak power pulses and closes three optical links which include Low Earth Orbit (LEO) to Earth, LEO to LEO, and Moon to Earth. Additionally, a benchtop version of the amplifier design was constructed and was able to produce amplified pulses with 1.37 W peak power, including a 35.7% transmit optics loss, at a pump power of 500 mW. Finally, the modulator, seed laser, amplifier, receiver, and time-to-digital converter were all used together to measure the Bit Error Ratio (BER), which was 0.00257 for a received optical peak power of 176 nW.
Precision space inertial sensors used for satellite geodesy missions, tests of fundamental physics, and gravitational wave observation utilise UV photoemission to control the electric potential of free-falling test masses with respect to their surrounding electrode housings. Successful generation of photoelectrons requires UV light energies greater than the work function of the illuminated surface. To ensure bi-polar test mass charge control (positive and negative charge rates), the quantum yields of the test mass and electrode housing surfaces must be well-balanced. LISA Pathfinder used mercury vapour lamps at 254 nm to discharge the gold coated test mass by likely relying on contaminants to lower the work function of gold from its nominal value of 5.2 eV. The LISA gravitational wave mission plans to use UV light emitting diodes (LEDs) instead of mercury vapour lamps. These UV LEDs have a lower mass, higher power efficiency, and produce light at wavelengths below 240 nm. In this paper, we measure the quantum yields of several Au-coated surfaces over a range of UV wavelengths and environmental conditions, varying temperature, vacuum pressure, and measuring over long periods of time. We use these data to draw conclusions and make recommendations for the development and handling of precision space inertial sensors for LISA and for other missions in the future.
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