Compact fiber-Bragg-grating detector for high-sensitivity ultrasound measurements

Amir Rosenthal, Daniel Razansky, Vasilis Ntziachristos

Research output: Contribution to conferencePosterpeer-review


Piezoelectric sensors constitute the method of choice in most
applications of optoacoustic imaging. One of the main drawbacks of
these sensors is their sensitivity, which is proportional to detection area.
As a result, when small detectors are required the sensitivity offered by
piezoelectric technology may not be sufficient.
In this work we demonstrate a sensitive compact hydrophone based
on a pi-phase shifted fiber Bragg grating. The grating exhibits a
sharp resonance, whose central wavelength is pressure sensitive.
The resonance is monitored by a continuous-wave laser to measure
ultrasound-induced pressure variations within the grating. In contrast to
standard fiber sensors, the high finesse of the resonance - which is the
reason for the sensor’s high sensitivity - is not associated with a long
propagation length. Light localization around the phase shift reduces
the effective size of the sensor below that of the grating and is scaled
inversely with the resonance spectral width. In our system, an effective
sensor length of 270μm, pressure sensitivity of 440 Pa, and effective
bandwidth of 10MHz were achieved. This performance makes our
design attractive for medical imaging applications, such as optoacoustic
tomography, in which compact, sensitive, and wideband acoustic
detectors are required.
Original languageAmerican English
StatePublished - 2012
Externally publishedYes
EventSPIE Photonics West 2012 - San Francisco, United States
Duration: 21 Jan 201226 Jan 2012


ConferenceSPIE Photonics West 2012
Country/TerritoryUnited States
CitySan Francisco
Internet address


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