Ultralow-V{\pi}L Silicon Electro-Optic Directional Coupler Switch with a Liquid Crystal Cladding

TL;DR

This paper demonstrates an ultralow-voltage silicon electro-optic switch using liquid crystal cladding, achieving high efficiency, low power consumption, and small footprint, suitable for integrated photonic switch matrices.

Contribution

The work introduces a silicon directional coupler switch with ultralow VπL and liquid crystal cladding, outperforming traditional MZI switches in footprint and optical loss.

Findings

Modulation efficiency of 0.0195 Vmm achieved

Power consumption below 0.6 nW

Extinction ratio of ~9dB at 1550 nm

Abstract

An ultralow-V{\pi}L photonic switch device is demonstrated utilizing the high optical and electrical field confinement in silicon slot waveguides coupled with the strong electro-optic response of nematic liquid crystals. A silicon photonic directional coupler switch with a modulation efficiency of 0.0195 Vmm and a loss-efficiency product of 0.0624 VdB is achieved. The 1.5 mm long device is based on two-mode interference within a single slot waveguide resulting in a V{\pi} of 0.013 V and an extinction ratio of ~ 9dB at 1550 nm wavelength. The power consumption of the photonic switch is estimated to be below 0.6 nW and it possesses a response time of <1.5 ms. A comparative performance study between the directional coupler switch and a Mach-Zehnder Interferometer (MZI) switch is performed. The directional coupler switch is projected to have a smaller footprint and lower optical loss compared to a similar design MZI switch making it a strong candidate for switch matrix designs and applications.