High sensitivity broadband optomechanical accelerometer based on spatio-temporal modulation of laser power in pyramidal horn

We developed an optomechanical accelerometer based on the passage of a laser beam through a pyramidal horn. It has been analytically proven that, as a result of multiple reflections of light within the vibrating horn, a longitudinal shift in the beam path occurs at the output. Consequently, this leads to changes in the beam’s diffraction properties at the output edge, deflection of the spreading light, and deep modulation of beam power. Thus, the horn’s vibrating sheet induces a beam shift at the photodetector, which is more than three orders of magnitude greater than the sheet’s displacement. This phenomenon is utilized in the experiment to spatially and temporally modulate the beam power incident on the photodetector. A smartphone vibromotor or a speaker attached to the horn’s sheet is used as the vibration source. The smartphone vibromotor, operating with relatively small displacements at frequencies of 80 and 100 Hz, enables the estimation of the system’s acceleration sensitivity and resolution. Specifically, at 80 Hz, an unprecedented sensitivity level of 1518.52 V/g is achieved, with a low resolution of 0.95 μg. In addition, a speaker is used to determine the accelerometer’s frequency response within the 20 to 2 kHz range.