Fig. 1. Spectral emission rate of type I (black solid) and type II (red solid) QPM SPDC in a 2 cm-long 5% MgO:PPLN waveguide at the temperature of 20°C versus the signal wavelength. Curves of type 0, type I, and II have an FWHM of 54.3, 48.5, and 0.4 nm, respectively.

Fig. 2. Scheme of the proposed source. The red arrows show the propagation direction of the pump laser, and the blue arrows show that of the fiber communication band photon pairs created in the crystal.

Fig. 3. Tuning curves of the photon pairs generation rate of type I QPM SPDC as a function of the crystal temperature in a 2 cm-long MgO:PPLN crystal. Two non-overlapping channel bands (black arrows) are supported at 20°C and 21°C.

Fig. 4. Comparisons between QPM SPDC bandwidths of type 0, type I, and type II. The red, black, and blue solid lines represent type 0, type I, and type II, respectively. (a) The phase mismatching parameters as functions of the signal wavelengths of type 0, type I, and type II. (b) QPM SPDC bandwidths as functions of the interaction lengths of type 0, type I and type II.