Silicon Oxycarbide Waveguides for Photonics Applications

The photonics technology has seen a dramatic growth over the past decades. Several material platforms have been explored to cater day-to-day needs of the integrated optics industry. However, the well-established platforms such... [ view full abstract ]

The photonics technology has seen a dramatic growth over the past decades. Several material platforms have been explored to cater day-to-day needs of the integrated optics industry. However, the well-established platforms such as SiO₂, SiN, Si, and InP are limited in their refractive index tunability. Silicon oxycarbide (SiOC), on the other hand, has a potential of wide refractive index tunabilty extending from silica to silicon carbide. 

In the present work, comprehensive study of silicon oxycarbide (SiOC) films prepared with reactive rf magnetron sputtering and the use of SiOC as a core material for optical waveguides have been demonstrated for the very first time. Thanks to the refractive index tunabilty (1.45 to 3.0) and lower extinction coefficient offered by SiOC in the near-infrared spectrum, development of a range of passive optical devices is possible on a single material platform.

We have fabricated channel waveguides with SiOC core using UV photolithography and reactive ion etching techniques. SiOC cores with two high index values, n = 1.578 and 1.82 at 1550 nm, have been buried in SiO₂ giving a high index contrast optical waveguides (8% and 18%) respectively. 

The SiOC waveguides have been characterized at telecom wavelength 1550 nm and propagation losses of 0.4 dB/mm and 0.8 dB/mm are estimated for two high contrast SiOC waveguides, respectively. Using the dispersion information from ellipsometry, the group dispersion of the optical waveguides has been estimated that agrees with experimental results.

In conclusion, we have been successful in demonstrating SiOC films characteristics and fabricating photonic waveguides with two high refractive indices. Our study solves the problem of refractive index tunable optical material providing acceptable losses in the telecom wavelength range and opens a door for the use of SiOC as a potential candidate in integrated optics.