Interfacing Silicon Nanophotonic Integrated Circuits and Single-Mode Optical Fibers with Diffraction Gratings

Abstract

Exploiting the high refractive index contrast achievable on the silicon-on-insulator (SOI) material platform enables a drastic scaling down of the footprint of integrated optical functions. While this allows for large-scale integration of optical functions, it severely complicates the interfacing with a single-mode optical fiber, due to the huge mismatch in mode size between the optical fiber and nanophotonic silicon waveguide. In this chapter we elaborate on the use of diffraction gratings to achieve an efficient, compact, alignment-tolerant, polarization-independent, and broadband optical coupling. Besides using these components as an interface with an optical fiber, its use to interface with opto-electronic components will be discussed. Finally, an optical probe will be presented, based on a diffraction grating integrated on the facet of a single-mode fiber. Such an optical probe allows testing of individual components in a silicon-on-insulator nanophotonic integrated circuit.