Temporal characterization of broadband femtosecond laser pulses by third-harmonic dispersion scan with ptychographic retrieval

TL;DR

This paper introduces a novel third-harmonic dispersion scan method utilizing ptychographic retrieval for full amplitude and phase characterization of broadband femtosecond laser pulses, demonstrating high accuracy and broad wavelength applicability.

Contribution

The work presents a new dispersion scan technique based on surface third-harmonic generation and ptychographic algorithms, enabling complete pulse retrieval without phase-matching constraints.

Findings

Accurately measured 7 fs pulses from a Ti:Sapphire oscillator.

Achieved pulse compression consistent with standard d-scan results.

Demonstrated broadband applicability into the mid-infrared range.

Abstract

We present a new variant of dispersion scan (d-scan) based on surface third-harmonic generation (STHG) and a ptychographic algorithm taylored for full retrieval (amplitude and phase) of broadband laser pulses. We demonstrate the technique by temporally measuring and compressing few-cycle pulses with 7 fs and 2.5 nJ from a Ti:Sapphire oscillator, using a sapphire window as the nonlinear medium. The results are in very good agreement with standard second-harmonic d-scan measurements based on a nonlinear crystal. The intrinsically broadband and phase-matching-independent nature of STHG make this technique very suitable for the characterization of ultrashort laser pulses over a broad wavelength range extending into the mid-infrared.