We reveal the generation of a broadband (> 1.9 THz) bi-photon quantum frequency comb (QFC) in a silicon-on-insulator (SOI) Fabry–Pérot micro-cavity and the control of its spectral correlation properties. Correlated photon pairs are generated through three spontaneous four-wave mixing (SFWM) processes by using a co-polarized bi-chromatic coherent input with power P 1 and P 2 on adjacent resonances of the nonlinear cavity. Adjusting the spectral power ratio r = P 1 /( P 1 + P 2 ) allows control over the influence of each process leading to an enhancement of the overall photon pair generation rate (PGR) μ ( r ) by a maximal factor of μ ( r = 0.5)/ μ ( r = 0) ≈ 1.5, compared to the overall PGR provided by a single-pump configuration with the same power budget. We demonstrate that the efficiency a ND of the non-degenerate excitation SFWM process (NDP) doubles the efficiency a 1 ≈ a 2 of the degenerate excitation SFWM processes (DP), showing a good agreement with the provided model.
We reveal the generation of a broadband (> 1.9 THz) bi-photon quantum frequency comb (QFC) in a silicon-on-insulator (SOI) Fabry–Pérot micro-cavity and the control of its spectral correlation properties. Correlated photon pairs are generated through three spontaneous four-wave mixing (SFWM) processes by using a co-polarized bi-chromatic coherent input with power P 1 and P 2 on adjacent resonances of the nonlinear cavity. Adjusting the spectral power ratio r = P 1 /( P 1 + P 2 ) allows control over the influence of each process leading to an enhancement of the overall photon pair generation rate (PGR) μ ( r ) by a maximal factor of μ ( r = 0.5)/ μ ( r = 0) ≈ 1.5, compared to the overall PGR provided by a single-pump configuration with the same power budget. We demonstrate that the efficiency a ND of the non-degenerate excitation SFWM process (NDP) doubles the efficiency a 1 ≈ a 2 of the degenerate excitation SFWM processes (DP), showing a good agreement with the provided model.
The photon pair generation (PPG) via spontaneous four-wave mixing (SFWM) in an optically excited third-order nonlinear cavity forms large-scale high-dimensional quantum states, called quantum frequency combs (QFC). The scalable practical generation and control of these photonic states via integrated devices enable quantum information processing for applications in secured communications and quantum computing [1]. Modifying the excitation field properties in different degrees of freedom, e.g., polarization [2], frequency or spatial modes [3], allows controlling the structure of the generated quantum state by favoring different types of SFWM processes. In this work, by using two excitation fields and varying their intensity,P1andP2, respectively, we demonstrate the occurrence of two different SFWM processes (degenerately and non-degenerately excited SFWM) and a control of the pair generation rate:μ(r,P)=μ1(P1(r,P))+μ2(P2(r,P))+μND(r,P), where P is the total excitation power,r=P1/Pis the power ratio,μ1,μ2describe the degenerate process andμNDthe non-degenerate process.
), such as aluminum gallium arsenide (AlGaAs), enable efficient nonlinear interactions at low excitation powers in integrated cavities. Here, we demonstrate a broadband quantum frequency comb (QFC) in a low free spectral range (FSR) (45 GHz) aluminum gallium arsenide on insulator (AlGaAsOI) resonator, with up to 40 pairwise frequency-correlated modes across a 1.97 THz bandwidth in the C-band. The dense mode spacing enables scalable frequency multiplexing and frequency-bin encoding within a compact device operating at a low excitation power of 6.33 µW. The measured joint-spectral intensity (JSI) is well reproduced by a theoretical model, enabling predictive control of spectral correlations across the generated QFC. The moderate Q-factor provides a tradeoff between nonlinear enhancement, broadband phase-matching, and number of accessible modes, supporting dense multimode operation over a large spectral range. These results highlight the potential of AlGaAsOI resonators for scalable low-power QFC sources.
We present a quantum-mechanical theory to describe narrowband photon-pair generation via four-wave mixing in a Silicon-on-Insulator (SOI) micro-resonator. We also provide design principles for efficient photon-pair generation in an SOI micro-resonator through extensive numerical simulations. Microring cavities are shown to have a much wider dispersion-compensated frequency range than straight cavities. A microring with an inner radius of 8 μm can output an entangled photon comb of 21 pairwise-correlated peaks (42 comb lines) spanning from 1.3 μm to 1.8 μm. Such on-chip quantum photonic devices offer a path toward future integrated quantum photonics and quantum integrated circuits.
Quantum correlations, where two or more parties exhibit strong correlations in a particular degree of freedom are important resources for fundamental science [1], such as the exploration of non-locality and entanglement, as well as non-classical technologies including quantum computation, quantum key distribution and quantum metrology. One typical way to generate correlated photon pairs is to use the spontaneous four-wave mixing process, with demonstrations on various platforms [2]. So far, single-photon stimulated four-wave mixing (FWM) has been demonstrated in optical fibers [3]. Here we show induced correlation by single photon seeded FWM through exploiting the orthogonal polarization modes in an integrated ring resonator [4]. We allow two different four-wave mixing processes to occur simultaneously with the same signal frequency mode but different idler frequency modes (see Fig.1(a)). The single-photon induced FWM process, named here seeded FWM, was created through the link of type-0 SFWM and type-2 SFWM. In the type-0 process, two excitation photons from the same field are converted into two new photons, signal and idler, with the same polarization as the pump field. While in the type-2 FWM, two annihilated photons, each one from a different polarized pump field, namely TE and TM, generate an orthogonal-polarized photon pair. More importantly, spatial and temporal overlapping of two processes and their sharing of one common resonance lead to correlation between the other two signal photons, one from each process. For example, an idler photon created in type-0 FWM seeds the type-2 FWM process or vice versa, i.e. the TM idler photon in Fig. 1, induces correlation between the signal TM and TE photons. This is proven by the observation of a clear coincidence peak for both signal photons in Fig.1(b). Furthermore, we confirmed our observation via power-dependent correlation measurements (see Fig.1 (c)). We summarized the true coincidence count (C) and its coincidence to accidental ratio (CAR) when only the TE pump power is increased while maintaining the TM mode pump power (black squares), and both pump powers are increased with a constant ratio (blue dots). We found that the seeded FWM scales with the square of both pump powers (C ∝ PjePtm) and that the CAR reach its maxima of 1.5 at the available pump power, indicating thermal statistics. Our findings are relevant to the fundamental understanding of spontaneous parametric effects as well as single-photon induced processes and single photon cloning.
Nowadays, Quantum Photonics finds a number of significant applications, such as Quantum Computing and Quantum Communication. Silicon on Insulator (SOI) technology has proven its potential for the generation of correlated photon pairs through the spontaneous four wave mixing (SFWM) effect, but not in the visible wavelength range. In this invited paper we present the physical investigation and design guidelines of AlGaN microring resonators for generating photon entanglement, as induced by SFWM in the visible. The work theoretically demonstrates the possibility of realizing the on-chip generation of correlated pairs of photons within integrated microring resonators based on the AlGaN/AlN technological platform, due to its wide bandgap, crystalline structure and low losses. Furthermore, general physical features are presented by means of a parametric analysis of the biphoton flux and cross correlation as a function of the device parameters, i.e. ring radius, resonator cross section and sizes, pulley coupling. Moreover, the spectral features of the generated signal and idler photons have been analyzed as a function of the pump resonance mismatch for several Kerr coefficients and input visible “blue” pump powers. Cross correlation values around 2.3 ×104at a biphoton flux of about 9×104pairs/s and 2×103at about 2.9×106pairs/s for ring radius of 200 μm and 30 μm have been achieved, respectively, assuming a input pump power of 25 mW, while the signal is generated at wavelength of 369.5 nm and idler at 535.72 nm, for ring radius of 200 μm, and 369.5 and 457.45 nm for ring radius of 30 μm, respectively. These devices can be important for many applications, going from UV-visible spectroscopy to quantum sensing to image processing to nonlinear optics.