Suppression of Parasitic Nonlinear Processes in Spontaneous Four-Wave Mixing with Linearly Uncoupled Resonators

We report on a signal-to-noise ratio characterizing the generation of identical photon pairs of more than 4 orders of magnitude in a ring resonator system. Parasitic noise, associated with single-pump spontaneous four-wave mixing, is essentially eliminated by employing a novel system design involving two resonators that are linearly uncoupled but nonlinearly coupled. This opens the way to a new class of integrated devices exploiting the unique properties of identical photon pairs in the same optical mode

On-chip generation of high-dimensional entangled quantum states and their coherent control

Optical quantum states based on entangled photons are essential for solving questions in fundamental physics and are at the heart of quantum information science1. Specifically, the realization of high-dimensional states (D-level quantum systems, that is, qudits, with D > 2) and their control are necessary for fundamental investigations of quantum mechanics2, for increasing the sensitivity of quantum imaging schemes3, for improving the robustness and key rate of quantum communication protocols4, for enabling a richer variety of quantum simulations5, and for achieving more efficient and error-tolerant quantum computation6. Integrated photonics has recently become a leading platform for the compact, cost-efficient, and stable generation and processing of non-classical optical states7. However, so far, integrated entangled quantum sources have been limited to qubits (D = 2)8, 9, 10, 11. Here we demonstrate on-chip generation of entangled qudit states, where the photons are created in a coherent superposition of multiple high-purity frequency modes. In particular, we confirm the realization of a quantum system with at least one hundred dimensions, formed by two entangled qudits with D = 10. Furthermore, using state-of-the-art, yet off-the-shelf telecommunications components, we introduce a coherent manipulation platform with which to control frequency-entangled states, capable of performing deterministic high-dimensional gate operations. We validate this platform by measuring Bell inequality violations and performing quantum state tomography. Our work enables the generation and processing of high-dimensional quantum states in a single spatial mode

All-fibered chalcogenide based continuous-wave parametric amplification in the mid-infrared

We demonstrate parametric amplification around 2 μm in a dispersion engineered tapered microstructured chalcogenide fiber. Almost 5 dB of signal amplification was achieved by 125 mW coupled power from a thulium-doped fiber pump laser

Characterization and modeling of microstructured chalcogenide fibers for efficient mid-infrared wavelength conversion

We experimentally demonstrate wavelength conversion in the 2 micron region by four-wave mixing in an AsSe and a GeAsSe chalcogenide photonic crystal fibers. A maximum conversion efficiency of -25.4 dB is measured for 112 mW of coupled continuous wave pump in a 27 cm long fiber. We estimate the dispersion parameters and the nonlinear refractive indexes of the chalcogenide PCFs, establishing a good agreement with the values expected from simulations. The different fiber geometries and glass compositions are compared in terms of performance, showing that GeAsSe is a more suited candidate for nonlinear optics at 2 micron. Building from the fitted parameters we then propose a new tapered GeAsSe PCF geometry to tailor the waveguide dispersion and lower the zero dispersion wavelength (ZDW) closer to the 2 mu m pump wavelength. Numerical simulations shows that the new design allows both an increased conversion efficiency and bandwidth, and the generation of idler waves further in the mid-IR regions, by tuning the pump wavelength in the vicinity of the fiber ZDW

Observation of second harmonic and sum frequency in an optically poled Si3N4 waveguide

Enhanced second order nonlinear processes in a Si3N4 waveguide following optically induced χ(2) is demonstrated, enabling the detection of a frequency doubled pulsed train and SFG with > -37 dB conversion efficiency for 18 W pump peak power

MIR supercontinuum in all-normal dispersion Chalcogenide photonic crystal fibers pumped with 2μm femtosecond laser

We demonstrate mid-infrared supercontinuum generation in an all-normal dispersion Chalcogenide PCF pumped by fiber laser. The -20dB bandwidth is 1.7~2.7μm dominated by self phase modulation and optical wave breaking. Tapering is proposed to improve performance

Small core Chalcogenide photonic crystal fiber for midinfrared wavelength conversion: Experiment and design

Kerr index and dispersion parameter of a small core chalcogenide photonic crystal fiber are estimated via four-wave mixing near 2 mu m. From these values, new fiber design is proposed to efficiently generate idlers in mid-infrared

Mid infrared gas spectroscopy using efficient fiber laser driven photonic chip-based supercontinuum

Directly accessing the middle infrared, the molecular functional group spectral region, via supercontinuum generation processes based on turn-key fiber lasers offers the undeniable advantage of simplicity and robustness. Recently, the assessment of the coherence of the mid-IR dispersive wave in silicon nitride (Si3N4) waveguides, pumped at telecom wavelength, established an important first step towards mid-IR frequency comb generation based on such compact systems. Yet, the spectral reach and efficiency still fall short for practical implementation. Here, we experimentally demonstrate that large cross-section Si3N4 waveguides pumped with 2 mu m fs-fiber laser can reach the important spectroscopic spectral region in the 3-4 mu m range, with up to 35% power conversion and milliwatt-level output powers. As a proof of principle, we use this source for detection of C2H2 by absorption spectroscopy. Such result makes these sources suitable candidate for compact, chip-integrated spectroscopic and sensing applications