Shades of Greyscale Tapers and Polymer Waveguides in Photonic Integrated Circuits

Abstract

The rapid development of silicon photonics over the last decade coupled with the increasing availability of silicon photonics chips through organizations such as AIM Photonics has created a need for advanced photonics technologies for chip-to-fiber, chip-to-chip, and chip-to-board interconnects. Refractive index contrast (RIC) polymers enable a range of photonic interconnect applications due to their tunable refractive indices and unique lithographic processing. By spatially increasing the index through conventional photolithographic methods using ultraviolet-irradiation, polymer waveguides are rapidly fabricated in dry films without the need for subsequent wet or dry etching. Depending on the composition of the polymer, the waveguide index contrast can range from 0.01 to 0.03, spanning indices from n=1.47 to 1.56. low-loss (< 1 dB/cm at 1310nm) single-mode waveguides were fabricated to demonstrate the initial proof of concept followed by the creation of greyscale tapers for adiabatic coupling to ion-exchange glass waveguides. These devices have low loss at telecommunication wavelengths (1310nm and 1550nm), opening the door to optical interconnect fabrics that combine silicon photonics with optical printed circuit boards for next generation data centers and other applications.