Two-colour balanced optical cross-correlator using fibre-coupled PPLN waveguides

TL;DR

This paper introduces a fibre-coupled balanced optical cross-correlator using PPLN waveguides for efficient sum-frequency generation between 1560 nm and 800 nm pulses, achieving high sensitivity and potential for further improvements.

Contribution

It demonstrates a novel fibre-coupled BOXC based on PPLN waveguides with significantly enhanced sensitivity over existing bulk-optic devices.

Findings

Sensitivity of 5.11 mV/fs achieved

Effective nonlinear coefficient of 16.1 pm/V

Potential for higher sensitivity with design optimizations

Abstract

We present a two-colour fully fibre-coupled balanced optical cross-correlator (BOXC) based on sum-frequency generation (SFG) between 1560 nm and 800 nm laser pulses using waveguides implemented in type-0 phase-matched periodically poled LiNbO$_{3}$ (PPLN) crystals. The interaction has an effective nonlinear coefficient of $d_{eff}$ = 16.1 pm/V, many times higher than comparable nonlinear crystals used for this SFG interaction such as barium borate (BBO). The resulting sensitivity of the cross-correlator is measured to be 5.11 mV/fs, five times greater than current bulk-optic BOXCs after accounting for differences in transimpedance gain and photodetector responsivity, with the potential for significantly higher sensitivity after optimisations to the cross-correlator design.