We propose novel Germania-glass fibers exploiting FWM to produce single-photons in 2 to 3 μm range. The phase matching conditions at different wavelengths can be fulfilled by employing different modes for pump, signal, and idler.
We report novel ZBLAN fibers exploiting SpFWM, generating single-photons in the 3 to4μmrange. The phase-matching condition can be fulfilled by choosing suitable spatial mode profiles for signal, pump, and idler wavelengths.
Near-infrared (NIR) single-photon sources have become the backbone of quantum technology. There is further potential to demonstrate the next-generation quantum technology applications by extending the wavelengths to the mid-infrared (mid-IR) region. This interest is driven by the extraordinary characteristics of the mid-IR wavelength spectrum. In this paper, we propose germania-doped and ZBLAN fibers that exploit spontaneous four-wave mixing (SpFWM) to generate a single photon-pair in the ∼2 µm to ∼3.5 µm wavelength range. The phase-matching conditions at different wavelengths can be achieved by employing both the same-mode and mixed-mode schemes (intra and intermodal) for the idler, pump, and signal wavelengths. For the intramodal scheme, we exploited the fiber’s high NA to produce closely spaced non-degenerate modes (such as LP 11a /LP 11b and LP 21a /LP 21b ) and then used combinations of these modes (from LP 11a to LP 11b or LP 21a to LP 21b ) for all three signal, pump, and idler wavelengths to achieve the phase-matching. For the intermodal scheme, we borrowed different modes for the signal, pump (including different modes for both pump photons), and idler wavelengths. The mixed-mode schemes allow for a larger core and provide greater flexibility in tuning the idler and signal wavelengths to mitigate the effects of Raman scattering and residual pump photons (∼20–25 THz from the pump frequency), albeit with increased complexity and reduced efficiency. We developed an understanding of the mixed-mode phase-matching scheme and built a model to optimize mode selection for phase-matching. Our investigations reveal, for the first time, the untapped potential of fiber-based mid-IR entangled single photon-pair generation.
The generation of single photons in the near-infrared range with a wavelength of 1533 nm is demonstrated. The generation is performed in an optical fiber using continuous-wave laser excitation and a heralding photon in the visible range with a wavelength of 520 nm. Despite relatively high pump powers and a significant contribution of noise photons, the presented source provides a high degree of single-photon generation purity ( gc(2)(0)=0.04) . This work reveals the potential for creating compact fiber-optic sources of single infrared photons using continuous-wave laser sources.
Visible-infrared photon pair sources working in broadband mid-infrared region are useful for applications such as heralded mid-infrared single photon sources. Here, we demonstrate experimentally a wavelength variable visible-infrared photon pair source in the mid-infrared region over a wide spectral range of 2 to 5 μm. By changing the angle of the nonlinear crystal in the source, the observed wavelengths of the signal photons change from 600 to 965 nm, corresponding to the idler wavelengths in 1186-4694 nm.