Novel on chip rotation detection based on the acousto-optic effect in surface acoustic wave gyroscopes

Abstract

An Acousto-Optic Gyroscope (AOG) consisting of a photonic integrated device embedded into two inherently matched piezoelectric surface acoustic wave (SAW) resonators sharing the same acoustic cavity is presented. This constitutes the first demonstration of a micromachined strain-based optomechanical gyroscope that uses the effective index of the optical waveguide due to the acousto-optic effect rather than conventional displacement sensing. The theoretical analysis comparing various photonic phase sensing techniques is presented and verified experimentally for the cases based on a Mach-Zehnder interferometer, as well as a racetrack resonator. This first prototype integrates acoustic and photonic components on the same lithium niobate on insulator (LNOI) substrate and constitutes the first proof of concept demonstration of the AOG. This approach enables the development of a new class of micromachined gyroscopes that combines the advantages of both conventional microscale vibrating gyroscopes and optical gyroscopes.

Progress of infrared guided-wave nanophotonic sensors and devices

“…Example of optomechanical accelerometer using zipper PhC nanocavity (Reproduced with permission from [236]). d Gyroscope: (i) microresonator Brillouin gyroscope based on Sagnac effect (Reproduced with permission from [241]); (ii) acousto-optic gyroscope (Reproduced with permission from [243]). e Torque/Magnetic field sensor: (i) torque sensor using nanobeam with two 1D PhC nanocavities (Reproduced with permission from [244]); (ii) magnetic field sensor using split-beam nanocavity (Reproduced with permission from [246]); (iii) magnetic field sensor using coupled optical microdisk resonator and arced torsional mechanical resonator (Reproduced with permission from [248]) a Si circular diaphragm was also developed, showing a minimum detectable force of 0.847 µN and a minimum detectable pressure of 4.17 MPa [226].…”

“…Mahmoud et al [243] investigated a novel optomechanical gyroscope by replacing the acousto-electrical detection in the surface acoustic wave (SAW) gyroscope with an acousto-optical detection method, which provides advantages of low noise level, high sensitivity, and stable readout. Figure 10d (ii) schematically illustrates the operation principle.…”

Low-loss waveguides on Y-cut thin film lithium niobate: towards acousto-optic applications

“…The emergence of lithium niobite on insulator (LNOI, thin film of LN bonded on low refractive index material) in the last two decades has led to rapid growth of LN photonics since its high index contrast waveguide structure enables dramatic reduction of the device footprint and enhancement of optical effects with respect to implementations in the bulk material [6]. Substantial cutting-edge research activities have flourished based on compact thin film LN photonic devices for a variety of applications [7][8][9][10][11][12][13][14][15]. For AO applications, LN features high elasto-optic coefficients like GaAs, but comes also with very strong piezoelectricity over many other materials (e.g., GaAs, ZnO, quartz…) [16], which results in acoustic devices that have a substantially higher electromechanical coupling coefficient [17] However, compared to more mature material platforms like silicon on insulator (SOI) and other semiconductor materials, producing low loss waveguides in LNOI is extremely challenging.…”

Thermal annealing study of the mid-infrared aluminum nitride on insulator (AlNOI) photonics platform

“…AlN offers advantages such as CMOS-compatibility, wide transparency window (0.2 -13.6 µm) [33] and high resistance to chemical and thermal perturbation [34]. The AlNOI platform can potentially offer piezoelectric tuning capability [35] and optical nonlinearity [36] enabled by its atomic structural asymmetry in the c-axis. Despite most of the good optical performances achieved in the reported AlNOI MIR photonics platform, one major drawback is the high propagation loss.…”