Mach-Zehnder Silicon Photonic Modulator Assisted by Phase-Shifted Bragg Gratings
Omid Jafari, Wei Shi, Sophie LaRochelle
Abstract
We experimentally demonstrate a silicon photonic Mach-Zehnder modulator (MZM) assisted by phase-shifted Bragg gratings. Coupled resonators are inserted in the Bragg grating structure to significantly enhance the phase modulation efficiency, while maintaining a wide optical bandwidth compared to other resonator-based modulators. Fabricated using a CMOS-compatible foundry process, the device achieved a small-signal V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">π</sub> × L of 0.18 V.cm, which is seven times lower than a conventional silicon MZM fabricated with the same process. The device has a compact footprint, with a length of only 162 μm, and shows a modulation bandwidth of 28 GHz at a reverse bias of 1 V. Non-return-to-zero modulation is demonstrated at 30 Gb/s with a bit-error-rate (BER) below the 7%-overhead forward error correction (FEC) threshold over a bandwidth of 3.5 nm. This bandwidth should translate into an operating temperature range greater than 40 °C.