Abstract
A new compact silicon grating coupler enabling fibre-to-chip light coupling at a minimized taper length is proposed. The proposed coupler, which incorporates a hollow tapered waveguide, converts the spot-size of optical modes from micro- to nano-scales by reducing the lateral dimension from 15 µm to 300 nm at a length equals to 60 µm. The incorporation of such a coupler in photonic integrated circuit causes a physical footprint as small as 81 µm × 15 µm with coupling efficiency and 3-dB coupling bandwidth as high as 72% and 69 nm respectively.
Highlights
High refractive index (RI) contrast in silicon-on-insulator (SOI) platforms enables multifunctional submicronic integration of photonic components in a single chip, it leads to the challenges of interfacing them with standard single mode fiber (SMF)[1]
It shows that coupling bandwidth (CBW) does not change much with the inclusion of the proposed taper, as expected, coupling efficiency (CE) reduces by 6% for hollow tapered waveguide (HTW) with 33 Si strips, as indicated earlier
The 2D Finite Difference Time Domain (FDTD) analysis shows that, with the basic HTW structure with 2 Si strips, only 47% of incident light could be coupled to the nano-scale waveguide
Summary
The design exercise performed in this investigation rely on widely used Finite Difference Time Domain (FDTD) method, which is a numerical analysis technique used for modelling computational electromagnetics by solving Maxwell’s equations. It consists of 2 μm thick SiO2 layer as BOX with 220 nm Si on top to ensure single mode operation. As the total height of top Si layer is 220 nm, a 125 nm Si base remains as a waveguide after etching 95 nm-depth gratings With all these necessary parameters optimized, the E-field distribution and propagation of light along the structure are shown, which were obtained by placing a power monitor across the structure.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
