High-Electron-Mobility Transistor-Inspired Freestanding AlGaN/GaN/AlN Optical Waveguide for High-Pressure Sensing Applications

Herein, a high-pressure sensor based on freestanding high-electron-mobility transistor (HEMT)-inspired optical waveguide comprising AlGaN/GaN/AlN layers on silicon carbide (SiC) substrate is proposed and studied for harsh environment applications using finite element method (FEM). The working principle of the sensor is based on the change in birefringence due to applied pressure. Further, the transmission spectra for different wavelengths are evaluated. For the best possible outcomes, the dip wavelengths under different values of pressure are tracked and studied for different gallium nitride (GaN) core thicknesses. After optimizing GaN core thickness and AlGaN ratio, the sensor displays a good linear response within the pressure range of 90-150 MPa. The two dip wavelength shifts demonstrate maximum spectral sensitivities of -209.6 and 180 pm MPa-1, respectively, for the pressure range of 90-150 MPa within the communication wavelength regime of 1500-1600 nm. By considering the features such as cost-effectiveness, portability, simple design, and easy detection process, the proposed pressure sensor is optimum for harsh environment measurements and studies.