Micro-machining of in-fibre 45° mirror optical fibre cantilever for dual-axis acceleration measurement

Focused ion beam (FIB) machining has been demonstrated to be capable of fabricating nano- and micro-scale structures. In this paper we demonstrate techniques to design and fabricate 45 degrees micro-mirrors into the end of multi-core fibres using FIB processing. The mirrors are fabricated by a two-step process: a scanning process which is used to make a rough cut followed by a polishing process to create an optical surface finish mirror. The machined 45 degrees mirrors can be accurately aligned with optical fibre cores, which avoids issues associated with the alignment of external turning mirror components. Proof-of-concept demonstration shows that the fabricated structure is capable of measuring two-axis acceleration interferometrically with a linear response from 0.2 to 4 g and an rms. error of 0.03 g. Acceleration measurements of frequency response up to 700 Hz and cross-sensitivity of similar to 4.3% are demonstrated.

Automated summary

In this paper, we demonstrate the design and fabrication of 45 degrees micro-mirrors using focused ion beam (FIB) processing. The mirrors are accurately aligned with optical fibre cores, eliminating the need for alignment of external turning mirror components. Experimental results show that the fabricated structure is capable of measuring two-axis acceleration with a linear response range of 0.2 to 4 g and an rms. error of 0.03 g. Frequency response up to 700 Hz and cross-sensitivity of approximately 4.3% are also demonstrated.