All-Fiber Broadband Photon Pair Generation in Dispersion Flattened Highly Non-Linear Fibers

We demonstrate an all-fiber broadband photon pair source based on four wave mixing (FWM) process in dispersion flattened highly non-linear fiber (DF-HNLF). The fiber exhibits a zero dispersion slope near 1550 nm, allowing phase-matched FWM over entire S, C, and L bands and thus efficient generation of signal and idler photons. A comparative theoretical study between conventional dispersion-shifted fiber (DSF) and DF-HNLF highlights the spectral range differences in the generation of photon pairs. We measure coincidence counts at three different sets of wavelengths. To study the effects of Raman scattering, which acts as noise source in these types of fibers, we calculate the correlation $g^{(2)}(\tau)$ at different pump powers. We use stimulated emission tomography to characterize the generation of photon pairs across the S, C, and L bands. We show that DF-HNLF is an ideal medium for generating correlated photons over a broad spectral range ($>\!\!100\,\text{nm}$), making it suitable for frequency-multiplexed quantum communication systems. We estimate the photon pair generation efficiency to be 0.05 $\text{mW}^{-2}/\text{pulse}$.