Fig. 2: Embedded Etalon Resonator (EER) characterization.
From: Bragg grating etalon-based optical fiber for ultrasound and optoacoustic detection
a The variation of the ultrasonic sensitivity of the EERs with (blue circles) or without (red diamonds) normalization to Q-factor, with respect to the change in spacer length (Lspacer). The red dashed line represents the simulated optical intensity that is exposed to ultrasound at the sensing facet. b Relationship between the sensitivity and noise-equivalent pressure (NEP) with respect to interrogation power. c Bandwidth response of the EER. d Experiment configuration for spatial response characterization of the EER in optoacoustic mesoscopy. e Projection of the measured spatial impulse response (SIR) along the lateral and axial directions at the imaging distances (D) of 0.5, 2, 5, and 8 mm. The scale bar corresponds to 40 µm. f Dependence of the full width at half maximum (FWHM) of the SIR on the imaging distance D.
