We present a general numerical model to quantify the impact of distributed linear propagation loss and nonlinear absorption losses on the temporal correlations between the paired photons generated in silicon nanowaveguides via spontaneous four-wave mixing.
Abstract We present a semi-classical numerical model to estimate the impact of linear scattering loss and nonlinear absorption losses on the biphoton flux and their quantum correlations generated via spontaneous four-wave mixing in silicon nanowaveguides. The counter-intuitive observed enhancement of pair correlations with increasing loss is attributed to the dominant effect of reduced accidental counts from multiphoton generation, with a corresponding trade-off for the source brightness. Silicon nanowaveguides are shown to be capable of generating highly correlated paired photons with coincidental-to-accidental ratio as high as ∼3400 and spectral brightness 2.8 × 10 4 pairs s−1 GHz−1 mW−1, even in the presence of linear propagation loss of 1 dB cm−1 and nonlinear losses (two-photon absorption and free-carrier absorption), over a length of 1 cm with an input pump power of 10 mW. Loss and the corresponding Langevin noise are modeled using distributed beam splitters along the waveguide length to encapsulate the phenomenological coupling to the background reservoir (vacuum fluctuations). The proposed numerical model is more general compared to previous analytical models, particularly for including dispersion and wavelength-dependent losses, and more accurate for noise estimation in the high-photon-flux regime such as optical parametric amplifiers and squeezed state generation.
Abstract Spontaneous four wave mixing in nonlinear waveguide is one of the excellent technique for generating photon pairs in well-defined guided modes. Here we present a comprehensive study of the frequency characteristic of correlated photon pairs generated in telecom C-band from a dispersion-engineered silicon wire waveguide. We have demonstrated that the waveguide configuration, shape of pump pulse, two-photon absorption as well as linear losses have significant influences on the biphoton spectral characteristics and the amount of frequency entanglement generated. The superior performance as well as the structural compactness and CMOS compatibility makes the silicon wire waveguide an ideal integrated platform for the implementation of on-chip quantum technologies.