High-speed silicon photonics modulators for the 2 μm wavelength

Abstract

The 2 µm communication windows has established itself amongst other solutions to address the capacity crunch. The 2 µm window offers three benefits: predicted ultra low loss windows of hollow-core fibres, optical amplification gain windows of thulium doped amplifier and compatibility with the silicon photonics silicon-oninsulator platform. We demonstrate state of the art high-speed modulators based on a 220 nm siliconon-insulator platform operating at a wavelength of 1950 nm using the free carrier plasma dispersion effect in silicon. The Mach-Zehnder interferometer carrierdepletion modulator has a modulation efficiency (Vπ·Lπ) of 2.89 V·cm at 4 V reverse bias. The insertion loss is 5.25 dB. It operates at a data rate of 25 Gbit/s OOK with an extinction ratio of 6.25 dB. We have also demonstrated a streamlined dual drive PAM4 generation method, producing 25 Gbit/s PAM4 signal using the same device. A Michelson interferometer is demonstrated with a Vπ·Lπ of 1.36 V·cm. It has almost double the efficiency of an equivalent MZM. It reaches a data rate of 20 Gbit/s. A broadband MZM was developed and its performance has been characterized at both 1550 nm and 1950 nm wavelengths. At 1950 nm, the carrier-depletion modulator operates at a data rate of 20 Gbit/s with an extinction ratio of 5.8 dB and insertion loss of 13 dB. The modulation efficiency (Vπ·Lπ) is 2.68 V·cm at 4 V reverse bias. At 1550 nm, an open eye is obtained at 30 Gbit/s. The difference in bandwidth is caused by the bandwidth limit of the 2 µm measurement setup. This work is a proof of principle demonstration, significantly improving previously published results and filling the long pending gap for the 2 µm silicon modulators. It paves a route towards a fully silicon-based transceiver in the 2 µm window.

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Identifiers

ORCID for Wei Cao: orcid.org/0000-0003-1431-7060

ORCID for Goran Mashanovich: orcid.org/0000-0003-2954-5138

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