Stable and precise optical bench for space applications

Abstract

We report a novel Optical Beam Steering Technique (OBST) for fiber to free-space to fiber coupling with extreme stability of the coupling efficiency and high tolerance to temperature fluctuations. The compact optical system is based near monolithic (ZERODUR) fiber couplers and relies on optical wedges and plates to perform the fine-steering of the optical beam. In our approach, we use coarsely aligned fiber couplers and then perform the fine alignment using the wedges and plates. This separation of fine and course tuning significantly reduces the manufacturing and assembly requirements of the fiber couplers. At the same time, it results in a much-reduced sensitivity to drifts increases the stability and reliability of the breadboard. OBST achieves a coupling efficiency (CE) of 94% with long-term fluctuation of 0.1% RMS at stable temperatures and 1.4% under repeated vacuum temperature cycling over a 30K range. Even under extreme mechanical stress (random vibrations of up to 8.3g) the RMS vibration of the coupling efficiency were less than 0.3% RMS. The optical breadboard technology has therefore achieved TRL5.