Hybrid Lithium Niobate and Silicon Photonic Waveguides

TL;DR

This paper presents a hybrid lithium niobate and silicon photonic waveguide platform with demonstrated optical components, achieving high LN confinement factors and comparable propagation losses to standard silicon waveguides.

Contribution

It introduces a hybrid LN/Si waveguiding platform with novel cross sections and adiabatic tapers to enhance LN confinement and mode preservation.

Findings

Achieved LN confinement factors of 32% and 90% in two cross sections.

Measured propagation loss of 4.3 dB/cm in cross section B.

Losses are comparable to standard silicon waveguides.

Abstract

We describe a hybrid lithium niobate (LN) / silicon (Si) optical waveguiding platform at near infrared wavelengths. Various optical circuit elements, such as waveguides, bends, and couplers are demonstrated in two hybrid cross sections, A and B, with different LN confinement factors (32% and 90%, respectively) of the fundamental quasi TE mode. Such a large LN confinement factor is achieved with adiabatic tapers that preserve the symmetry of the fundamental quasi TE mode and prevent mode rotation. We find the average propagation loss in cross section B to be 4.3 dB/cm with a standard deviation of 2.1 dB/cm, comparable with a 3 um SiO2 clad (in place of LN) Si waveguide whose average propagation loss was 3.1 dB/cm with a standard deviation of 2.1 dB/cm.