On-chip silicon photonics based grating assisted vibration sensor

Abstract

We present a compact, highly sensitive and scalable on-chip photonic vibration measurement scheme for vibration sensing. The scheme uses a silicon photonic diffraction-grating based sensor integrated underneath a silicon cantilever. We demonstrate a static and dynamic measurement sensitivity (ΔT/Δgap) of 0.6 % change in intensity per nm displacement. The electrostatically driven dynamic response measurement of the grating based sensor shows an excellent agreement with commercial Laser Doppler Vibrometer (LDV) measurement. We demonstrate the thermo-mechanical noise measurement on the cantilever in ambience, which is verified using LDV. A minimum displacement of 1.9 pm is measured with a displacement sensitivity of 10 μW/nm for a measurement bandwidth of 16 Hz. The demonstrated sensitivity is 2 orders of magnitude better than that obtained from measurements of static displacement. We also present a detailed 2D-FDTD simulation and optimization of the grating-based sensor to achieve maximum displacement sensitivity.

Miniaturization of Laser Doppler Vibrometers—A Review

“…Mere et al [112,113] demonstrated a vibrometer that is used to measure cantilever vibrations (Figure 8). In this configuration, light is sent to the PIC via a grating coupler.…”

“…This demonstration, however, is limited to measuring the vibration of a close-by and well-aligned cantilever. Mere et al [112,113] demonstrated a vibrometer that is used to measure cantilever vibrations (Figure 8). In this configuration, light is sent to the PIC via a grating coupler.…”

“…A schematic as shown in [46] is depicted in Figure 9. In Mere et al [112,113] demonstrated a vibrometer that is used to measure can vibrations (Figure 8). In this configuration, light is sent to the PIC via a grating coup the sensing grating, the measurement light is coupled out to the cantilever and i coupled back to the grating on the same waveguide.…”