Linear phase detection for a bimodal fiber sensor.
Interference between the LP(01) and LP(02) modes is used to measure fiber elongation. We present a passive phase-detection technique that uses a mask in the far field of the output beam and spatial filters in the image of the fiber end face, giving a linear response. Experimental results show a precision of about 3% of one period, which corresponds to a 4-microm elongation.
Spajer
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