Second-harmonic generation in periodically-poled thin film lithium niobate wafer-bonded on silicon

Abstract

Second-order optical nonlinear effects (second-harmonic and sum-frequency generation) are demonstrated in the telecommunication band by periodic poling of thin films of lithium niobate wafer-bonded on silicon substrates and rib-loaded with silicon nitride channels to attain ridge waveguide with cross-sections of ~ 2 µm 2 . The compactness of the waveguides results in efficient second-order nonlinear devices. A nonlinear conversion of 8% is obtained with a pulsed input in 4 mm long waveguides. The choice of silicon substrate makes the platform potentially compatible with silicon photonics, and therefore may pave the path towards on-chip nonlinear and quantum-optic applications. References and Links

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

“…In LNOI waveguides, QPM can be achieved by inverting the spontaneous polarization of the lithium niobate crystal periodically along the waveguide. The inversion of the crystal direction, also called domain inversion, can either be done before the lithium niobate thin‐film is bonded on the silica buffer layer in the LNOI wafer fabricated process or afterwards on the LNOI wafer itself . A method to generate domain patterns on LNOI is the electric field poling technique.…”

“…The periodic domain patterns achieved using digitated electrodes on X‐cut LNOI wafers have successfully been used for nonlinear optical applications, in ridge waveguides fabricated by SiN optical loading ( Figure a). Conversion efficiency of up to 160% W −1 cm −2 have been achieved as indicated in Figure c.…”

“…The inversion of the crystal direction, also called domain inversion, can either be done before the lithium niobate thin-film is bonded on the silica buffer layer [79] in the LNOI wafer fabricated process or afterwards on the LNOI wafer itself. [28,54,80,81] A method to generate domain patterns on LNOI is the electric field poling technique. This technique reverses the direction of the spontaneous polarization by locally applying an electric field along the polar z-axis of the crystal, exceeding the so-called coercive field.…”

A Review of Photonic Generation of Arbitrary Microwave Waveforms

“…Of particular note is the Silicon Photonic platform that has been extensively researched recently taking the advantages of the availability of the high performance and commercial grade device fabrication infrastructures of the electronic industry [34,35]. Another platform that recently attracts significant research interest is the thin-film Lithium Niobate wafer-bonded on Silicon which is compatible with Silicon Photonics and offers efficient second order nonlinearity [36]. Furthermore, the advancements in hybrid integration also allow combining of several different and occasionally exotic platforms together enabling the creation of solutions with functionalities that are not possible in a single platform [16,17,26].…”

Design of spontaneous parametric down-conversion in integrated hybrid SixNy-PPLN waveguides

“…In this work, we design a hybrid QPM waveguide structure of Si-rich silicon nitride (SixNy) waveguide and thin film PPLN for generating high-purity type-II SPDC photons, which combines two different device platforms and enables multifunctional chip-scale and wafer-level integration. For normal Si3N4, optical modes of the hybrid waveguide are mostly confined inside LN film because the refractive index of Si3N4 is smaller than that of the LN [13,18]. By using SixNy (with higher Si/N ratio than Si3N4), optical mode can be transferred from LN film to SixNy waveguide so that the reflection loss can be reduced at between the waveguide and the LN film.…”