Optical micro-knot resonator hydrophone

J. M. De Freitas, T. A. Birks, M. Rollings

Research output: Contribution to journalArticlepeer-review

22 Citations (SciVal)


We present results of what are believed to be the first underwater acoustic sensor using an optical micro-knot resonator. The mechanism involves straining the micro-fibre loop of the knot via an appropriate encapsulation material. The micro-knot sensor exhibited a spectral fullwidth half-depth of 37.7pm with a Q-factor of 41100 after deconvolution with the source. The shift in wavelength at 1550nm was observed to be around 67pm RMS when exposed to underwater acoustic excitation at 40Hz demonstrating a normalized sensitivity of -288 dB re μPa-1, or 5.83 fm/Pa.

Original languageEnglish
Pages (from-to)5850-5860
Number of pages11
JournalOptics Express
Issue number5
Publication statusPublished - 9 Mar 2015


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