Fig. 5: Noise performance experiment on the optomechanical MEMS geophone.
From: An optomechanical MEMS geophone with a 2.5 ng/Hz1/2 noise floor for oil/gas exploration
a Optical readout based on the balanced difference method. The three-channel outputs include the sensing path, reference path, and balanced differential path. b Noise power spectral density of the three output channels. The blue curve represents the sensing path noise, the red curve represents the reference path noise, the yellow curve represents the sensing path noise, the purple curve represents the quantization noise, the green dotted line represents the mechanical thermal noise, and the pink dotted line represents the photodetector (PD) noise. c Common-mode noise between the sensing noise and reference noise
