3D nano-printing coupler for Silicon Nitride suspended waveguide

One of the challenges in integrated photonics is to build optical coupler for seamless coupling the light from fiber to nano-size waveguides or devices on semiconductor or photonics based chips. Here we present a design and technique based on polymer-made 3D structure of nano/mico size for suspended Silicon Nitride nanobeam, a 3D coupler which has in-port for single mode fiber. We show a scattering-free design of the optical interface with some compromises due to resolution limited 3D printer tool with the fiber plug into interface feature. Finite-difference time-domain (FDTD) simulations are performed to optimize the tapering regions. With this optimization upto 95% waveguide to coupler and 62% coupler to waveguide transmission is obtained for large bandwidth(similar to 100nm) at 600 nm. Conical-shaped single mode fiber is fabricated using wet etching technique and plugged into 3D coupler to obtain a compact fiber-to-chip optical device.