Abstract
The inherent trade-off between efficiency and bandwidth of three-wave mixing processes in χ2 nonlinear waveguides is the major impediment for scaling down many well-established frequency conversion schemes onto the level of integrated photonic circuit. Here, we show that hybridization between modes of a silica microfiber and a LiNbO3 nanowaveguide, amalgamated with laminar χ2 patterning, offers an elegant approach for engineering broadband phase matching and high efficiency of three-wave mixing processes in an ultra-compact and natively fiber-integrated setup. We demonstrate exceptionally high normalized second harmonic generation (SHG) efficiency of up to ηnor ≈ 460% W−1 cm−2, combined with a large phase matching bandwidth of Δλ ≈ 100 nm (bandwidth-length product of Δλ · L ≈ 5 μm2) near the telecom bands, and extraordinary adjustment flexibility.
Highlights
We demonstrate exceptionally high normalized second harmonic generation (SHG) efficiency of up to ηnor ≈ 460% W−1 cm−2, combined with a large phase matching bandwidth of Δλ ≈ 100 nm near the telecom bands, and extraordinary adjustment flexibility
A possibility to substantially reduce the footprint of such devices, offered by the emergence of LiNbO3 on insulator (LNOI) nano-waveguides, could trigger a revolutionary advancement in design of functional ultra-compact quantum photonic components and circuits, including ultra-compact photon sources based on spatial multiplexing schemes[12]
We show that laminar nonlinearity patterning, by virtue of an embedded proton exchange (PE) layer, represents a distinctive way to break the fundamental bottleneck of poor modal overlap in conventional modal phase matching (MPM) scheme
Summary
We demonstrate exceptionally high normalized second harmonic generation (SHG) efficiency of up to ηnor ≈ 460% W−1 cm−2, combined with a large phase matching bandwidth of Δλ ≈ 100 nm (bandwidthlength product of Δλ · L ≈ 5 μm2) near the telecom bands, and extraordinary adjustment flexibility. A possibility to substantially reduce the footprint of such devices, offered by the emergence of LNOI nano-waveguides, could trigger a revolutionary advancement in design of functional ultra-compact quantum photonic components and circuits, including ultra-compact photon sources based on spatial multiplexing schemes[12]. Such devices require a convenient and compact nonlinear waveguide platform that offers the important combination of efficient and broadband χ2 functionality, low losses, including out-coupling losses to fiber-optic systems, and adjustability. Conventional approaches, involving manipulations with input fields (e.g. polarization and angle of incidence) and material structure (e.g. periodic poling), usually require a compromise between the efficiency, bandwidth, and overall size and complexity of the setup
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