Design of nanobeam photonic crystal resonators for a silicon-on-lithium-niobate platform

Abstract

We outline the design for a photonic crystal resonator made in a hybrid Silicon/Lithium Niobate material system. Using the index contrast between silicon and lithium niobate, it is possible to guide and confine photonic resonances in a thin film of silicon bonded on top of lithium niobate. Quality factors greater than 10 6 at optical wavelength scale mode volumes are achievable. We show that patterning electrodes on such a system can yield an electro-optic coupling rate of 0.6 GHz/V (4 pm/V).

Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits

“…Heterogeneous integration of bulk lithium niobate on platforms with a high refractive index contrast enables shorter bending radii and a higher integration density, while the attractive material properties of lithium niobate can still be employed. The heterogeneous integration of lithium niobate with SOI waveguides has attracted significant interest, which enabled electro‐optical tunable resonators, Mach‐Zehnder modulators and Mid‐IR modulators . Further, multiple die bonding enables integration on 200 mm and 300 mm SOI wafers .…”

High-Q photonic resonators and electro-optic coupling using silicon-on-lithium-niobate

“…32). The photonic crystal cavity consists of a silicon waveguide patterned with an array of elliptical holes.…”

“…where r is the third-rank electro-optic tensor, thereby shifting the optical resonant frequency of the cavity32. In the case of LN, the dominant electro-optic component is r 33  = 31 pm/V, which connects an applied electric field along the extraordinary ( Z ) axis to a change in the extraordinary index n e .…”

“…The fabrication flow for the hybrid silicon/lithium niobate structures is similar to the processes described in references 30, 31, 32 and 33 and is illustrated in Fig. 1(a).…”

“…We focus particularly on silicon-on-lithium-niobate (SiLN), in which single-crystal silicon photonic structures are directly bonded onto an LN substrate303132. In SiLN devices, the optical mode is confined by the silicon layer while still retaining modal overlap with the LN substrate.…”