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The measured fiber coupling efficiency (FCE) in atmospheric laser communication is not fully explored. We experimentally study the FCE for tip-tilt aberrations. Finally, we explain the FCE with the tip-tilt phase response.

We report the successful laser cooling of a Ytterbium-doped silica optical fiber glass preform by 0.7K relative to the room temperature. The observed temporal behavior of cooling agrees well with the theoretical predictions.

This paper describes an opto-mechanical concept of a deformable metal mirror membrane, which can shift the focus position over a large range by use of a single actuator. The core element of the mirror is a diamond turned tulip-shaped membrane, the design is optimized to correct astigmatic aberrations which arise from the use of a curved mirror under a deflection angle. For this purpose, the target mirror surface is biconic. The manufactured mirror was tested with a maximum central deflection of 28 µm and, when used in combination with a 200 mm focal lens, is capable of producing a focus shift of up to 17.9 mm with a resulting wavefront aberration of 238.7 nm RMS error .