Experimental characterization of three-wave mixing in a multimode nonlinear KTiOPO_4 waveguide

TL;DR

This paper experimentally characterizes three-wave mixing in a periodically poled KTiOPO_4 waveguide, revealing mode-dependent phase-matching properties that enable controlled photon pair generation in specific spatial modes.

Contribution

It provides the first detailed experimental measurement of the phase-matching function for type-II three-wave mixing in this waveguide, highlighting mode dependence and potential for quantum light sources.

Findings

Strong mode dependence observed in the signal

Full interpretation of mode effects achieved

Potential for generating photon pairs in specific spatial modes

Abstract

We report experimental determination of the phase-matching function for type-II three-wave mixing in a periodically poled KTiOPO_4 waveguide in the 792-815 nm spectral region. The measurement was performed by sum-frequency generation of spectrally tuned fundamental components. Strong dependence of the observed signal on the excited spatial modes in the waveguide has been observed and fully interpreted. These results indicate a route to employ the waveguide for spontaneous parametric down-conversion producing photon pairs in well-defined spatial modes.