Fig. 2: Experimental results of the guiding and scattering of |ψ_± >.

a An Nd:YAG 1064.5 nm pulsed laser (pump) is focused to a waist of ~450 µm inside the PS waveguide, hence can be assumed as a plane wave, with a peak power of 14 MW/cm². Increasing the pump power resulted in a slightly increased separation (Supplementary Materials). Through a dichroic mirror (DM), the 1550 nm continuous wave (CW) laser is focused to ~30 μm at the PS waveguide input facet. The PS waveguide is mounted on an oven with a temperature controller (58°). The pump and signal beams are filtered, and the output facet is imaged using a lens. The signal is recorded using a CCD camera. Experimental b and simulated c near field images of the signal field at the output facet, showing the guided eigenstate \(\left|{\psi }_{+}\right\rangle\) in the middle, fully guided along the ‘x’ axis and freely propagating along the ‘y’ axis, as well as the scattered, unguided eigenstate \(\left|{\psi }_{-}\right\rangle\). The dashed white circle represents the calculated beam size in the case of a homogeneous PPKTP crystal, without guiding. The dashed white lines mark the region along ‘X’ of the PS waveguide. d Summation (along the ‘Y’ axis) of the output near field. Comparison between the PS waveguide (orange) and a 1D PPKTP signal output (blue). The waist of the guided mode is ~5 times narrower than the homogeneous PPKTP signal output waist.