Small Sensitivity to Temperature Variations of Si-Photonic Mach–Zehnder Interferometer Using Si and SiN Waveguides

Tatsurou Hiraki,Tsuyoshi Yamamoto,Hiroshi Fukuda,Koji Yamada

doi:10.3389/fmats.2015.00026

Abstract

We demonstrated a small sensitivity to temperature variations of delay-line Mach-Zehnder interferometer (DL MZI) on a Si photonics platform. The key technique is to balance a thermo-optic effect in the two arms by using waveguide made of different materials. With silicon and silicon nitride waveguides, the fabricated DL MZI with a free-spectrum range of ~40 GHz showed a wavelength shift of -2.8 pm/K with temperature variations, which is 24 times smaller than that of the conventional Si-waveguide DL MZI. We also demonstrated the decoding of the 40-Gbit/s differential phase-shift keying signals to on-off keying signals with various temperatures. The tolerable temperature variation for the acceptable power penalty was significantly improved due to the small wavelength shifts.

Highlights

Silicon (Si) photonics is one of the most promising technologies for overcoming the limitations on integration in commercially available silica-based planar-lightwave circuits
It is clear that the Si–silicon nitride (SiN)-waveguide delay-line Mach–Zehnder interferometer (DL Mach–Zehnder interferometers (MZIs)) highly suppresses the wavelength shift with temperature variations
The TO effects of the fabricated SiN- and Si waveguides are almost consistent with their designs

Summary

Introduction

Silicon (Si) photonics is one of the most promising technologies for overcoming the limitations on integration in commercially available silica-based planar-lightwave circuits This is because it provides ultra-compact waveguides and makes the monolithic integration of active and passive devices possible (Lockwood and Pavesi, 2010; Vivien and Pavesi, 2013). We reported control of the refractive indices and TO coefficients of complementary metaloxide semiconductor (CMOS) compatible materials by changing the atomic composition of SiOx, SiOxNy, and SiN (Tsuchizawa et al, 2011; Nishi et al, 2012; Hiraki et al, 2013) Using these materials, in this work, we minimized the temperature sensitivity of the DL MZI. As a feasibility demonstration, we show the thermal stability of the decoding of differential phase-shift eying (DPSK) signals to on-off keying (OOK) signals at 40 Gbit/s

Methods

Results

Conclusion