Berry Smutny

5.6 Gbps optical intersatellite communication link

A 5.6 Gbps optical communication link has been verified in-orbit. The intersatellite link uses homodyne BPSK (binary phase shift keying) and allows to transmit data with a duplex data rate of 5.6 Gbps and a bit error rate better than 10-9 between two LEO satellites, NFIRE (U.S.) and TerraSAR-X (Germany). We report on the terminal design and the link performance during the measurement campaign. As an outlook we report on the flight units adapted to LEO-to-GEO intersatellite links that TESAT currently builds and on plans to study GEO-to-ground links.

High stability, fast tunable single frequency laser source for space based lidar applications

This paper describes the design and performance of the TESAT Reference Laser Head, acting as the frequency reference for the ALADIN Transmit Assembly (TXA) for the ESA AEOLUS satellite. First measurements of short time frequency stability (130 kHz rms over 360 sec) and digitally controlled coarse and fine step tuning functionality will be presented.

Space qualified laser sources

Tesat-Spacecom has developed a series of fiber coupled single frequency lasers for space applications ranging from onboard metrology for space borne FTIR spectrometers to step tunable seed lasers for LIDAR applications. The cw-seed laser developed for the ESA AEOLUS Mission shows a 3* 10-11 Allen variance from 1 sec time intervals up to 1000 sec. Q-switched lasers with stable beam pointing under space environments are another field of development. One important aspect of a space borne laser system is a reliable fiber coupled laser diode pump source around 808nm. A dedicated development concerning chip design and packaging yielded in a 5*106h MTTF (mean time to failure) for the broad area emitters. Qualification and performance test results for the different laser assemblies will be presented and their application in the different space programs.

Frequency-stable seed laser for the Aeolus mission

Coherent LIDAR systems require a frequency-stable and tunable seed laser source [1]. In general, a cw laser acts as an injection seeder for a Master Oscillator Power Amplifier system. The seed laser has to be a singlefrequency source that can be tuned over several GHz in order to compensate for Doppler-induced frequency shifts of the return signal. For the ESA AEOLUS mission [2], Tesat-Spacecom has developed and flightqualified a cw 1064 nm seed laser, the Reference Laser Head (RLH) for the high-power UV Doppler LIDAR instrument ALADIN [3]. Three RLH flight models (FMs) have been delivered. This paper details their design and performance data measured during development, qualification, and acceptance test campaigns. The lasers and laser diode pump modules are spin-offs of Tesat-Spacecoms development for intersatellite coherent laser communication terminals [4].

High stability lasers for lidar and remote sensing

Tesat-Spacecom is currently building a set flight models of frequency stabilized lasers for the ESA Missions AEOLUS and LTP. Lasers with low intensity noise in the kHz region and analogue tuning capabilities for frequency and output power are developed for the on board metrology of the LTP project, the precursor mission for LISA. This type of laser is internally stabilized by precise temperature control, approaching an ALLAN variance of 10-9 for 100 sec. It can be easily locked to external frequency references with <50kHz bandwidth. The Seed laser for the AEOLUS mission (wind LIDAR) is used as the master frequency reference and is stabilized internally by a optical cavity. It shows a 3* 10-11 Allan variance from time intervals 1 sec - 1000 sec. Furthermore it is step-tunable for calibration of the receiver instrument with a speed of GHz / sec by a digital command interface. Performance and environmental test results will be presented.

New 808 nm high power laser diode pump module for space applications

New pump module concepts had to be developed for space borne applications, because a simple transformation of terrestrial solutions to space requirements was often not useful. A planar approach has been chosen, which prevents inherent draw-backs of stacks.

Design study for high-performance optical communications satellite terminal with high-power laser diode transmitter

The present optical terminal design for a high data rate interorbit communications link with 500 Mbit/sec (or higher) transmission rate is based on high-power laser diode transmitters with 1 W peak power at 800 nm, in conjunction with a direct-detection receiver; two-channel wavelength-division multiplexing, together with the high transmission capability of the off-axis telescope used, contribute to the achievement of the requisite data rates. In order to minimize system mass, the only rotatable device is the telescope.