Freestanding HEMT Inspired GaN Based Optical Pressure Sensor With Grating Coupler

One key challenge encountered by photonic integrated circuit is to couple light to and from optical fibers efficiently. The standard fiber used for telecommunication or data communication is single-mode fiber (SMF), which has a mode field diameter (MFD) of less than equal to 10µm at 1550 nm. Efficient coupling from SMF to waveguide with size of hundreds of nanometers is a challenge due to the large mode field mismatch. This problem is usually addressed using two solutions, in-plane or butt edge coupling and out plane (vertical) grating coupling. To ensure good coupling efficiency along with practical feasibility, the grating on freestanding HEMT inspired GaN optical waveguide is a suitable choice for desired wavelength profile with high sensitivity. In this paper, the vertical gratings are introduced on freestanding HEMT inspired GaN optical waveguide for high pressure sensor applications.