Abstract
A modified LIGA process is well suited to fabricate hybrid mounted low-cost microoptical benches for fibre and free-space applications. The benches enable optical components to be assembled with lithographic precision in the LIGA plane without any active alignment. Due to the different sizes of the optical components, stepped substrates for X-ray lithography are required in order to guarantee a vertical alignment on the optical axis. Silicon and high-precision mechanical micromachining have been combined with the LIGA process to fabricate these benches. In addition, two alignment strategies were tested.
For applications with single-mode fibres two examples, a bi-directional duplexer and a fibre-fibre-coupler with an imaging set-up, have been fabricated by deep X-ray lithography as well as by moulding techniques. The insertion losses are approx. 2 dB in case of the coupler and 5 dB for the laser diode/fibre coupling res. 0.5 dB for fibre/photo diode coupling in the duplexer. The experimental results demonstrate the excellent positioning quality and are promising for industrial applications.
In the paper the various process techniques and the results of the precision measurements are presented. The opitcal performance of the set-ups is discussed.
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The project was funded by the German Federal Ministry for Education and Research (BMBF) under grant 13 MV 0092 (AVT-KEO).
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Müller, A., Göttert, J., Mohr, J. et al. Fabrication of stepped microoptical benches for fibre and free space applications. Microsystem Technologies 2, 40–45 (1996). https://doi.org/10.1007/BF02447748
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DOI: https://doi.org/10.1007/BF02447748