Feasibility of guided-wave optical microphone based on elasto-optic effect

Nikkuni, Hiroyuki; Ohkawa, Masashi; Sekine, Satoshi; Satō, Takashi

doi:10.1117/12.649176

Cited by 1 publication

(6 citation statements)

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“…3,4,6,7 In this study, phase sensitivity, defined as the induced phase difference per unit pressure, is used as microphone sensitivity. The phase sensitivity and the resonance frequency were calculated, following the mathematical description in Refs.…”

Section: Designing Of the Guided-wave Optical Microphonementioning

confidence: 99%

“…A number of optical microphones have been developed to detect sound waves even under strong electromagnetic fields. [1][2][3][4] Our group has also demonstrated silicon-based and glass-based guided-wave optical microphones. 3,4 The guided-wave optical microphones have advantages such as alignment-free and stout configurations, compactness and lightness besides immunity to electromagnetic interference.…”

Section: Introductionmentioning

confidence: 96%

“…[1][2][3][4] Our group has also demonstrated silicon-based and glass-based guided-wave optical microphones. 3,4 The guided-wave optical microphones have advantages such as alignment-free and stout configurations, compactness and lightness besides immunity to electromagnetic interference. In our previous study, the minimum detectable sound pressure level of a fabricated glass-based guided-wave optical microphone was estimated to be 140 dB-SPL or higher.…”

Section: Introductionmentioning

confidence: 96%

“…Phase sensitivity of the fabricated microphone was experimentally evaluated to be 2.4 mrad/Pa, which is 2.6 times higher than that in the previous report. 3 Also, noise of the optical microphone was drastically reduced by a bandpass filter with passband from 300 Hz to 3 kHz. By increasing sensitivity and reducing noise, the S/N ratio was improved by a factor of approximately 100.…”

Section: Introductionmentioning

confidence: 99%

“…In our previous study, the minimum detectable sound pressure level of a fabricated glass-based guided-wave optical microphone was estimated to be 140 dB-SPL or higher. 3 Since it is desirable that the optical microphone detect normal speech ranging from 55 to 65 dB-SPL, the signal-to-noise ratio (S/N ratio) of the guided-wave optical microphone must be improved by a factor of more than 10 4 by increasing sensitivity and reducing noise. Incidentally, sensitivity of the microphone and resonance frequency of the diaphragm are dependent on the diaphragm dimensions.…”

Section: Introductionmentioning

confidence: 99%

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Improvement of the signal-to-noise ratio in a glass-based guided-wave optical microphone

et al. 2007

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In this study, the signal-to-noise ratio of a glass-based guided-wave optical microphone was successfully improved by both increasing sensitivity and reducing noise. The optical microphone has a square diaphragm as a pressure-sensitive structure and a straight single-mode waveguide across the diaphragm. Sensitivity of the microphone and resonance frequency of the diaphragm are dependent on the area and thickness of the diaphragm. In this study, in order to increase sensitivity, the diaphragm dimensions were enlarged from 16 mm×16 mm×0.15 mm in the previous study to 20 mm×20 mm×0.15 mm. According to theoretical calculations, the phase sensitivity and resonance frequency were 2.5 mrad/Pa and 3.4 kHz for a 20 mm×20 mm×0.15 mm diaphragm, respectively. The sensitivity was theoretically expected to be twice as high as that in the previous study. To reduce noise, a bandpass filter with passband from 300 Hz to 3 kHz was employed. After fabrication of the optical microphone, sound pressure, ranging from 100 to 122 dB-SPL, was applied to the microphone with a frequency of 1 kHz. The measured output of the optical microphone was almost proportional to the sound pressure, and the minimum detectable sound pressure level of the microphone was experimentally evaluated to be 100 dB-SPL.

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Section: Designing Of the Guided-wave Optical Microphonementioning

confidence: 99%