Characterizing the carrier-envelope phase stability of mid-infrared laser pulses by high harmonic generation in solids

A Leblanc,Gilles Dalla-Barba,P Lassonde,F Légaré,E Cormier,H Ibrahim

doi:10.1364/oe.388465

Abstract

We present a novel approach for measuring the carrier-envelope phase (CEP) stability of a laser source by employing the process of high harmonic generation (HHG) in solids. HHG in solids driven by few-cycle pulses is very sensitive to the waveform of the driving pulse, therefore enabling to track the shot-to-shot CEP fluctuations of a laser source. This strategy is particularly practical for pulses at long central wavelength up to the mid-infrared spectral range where usual techniques used in the visible or near-infrared regions are challenging to transpose. We experimentally demonstrate this novel tool by measuring the CEP fluctuations of a mid-infrared laser source centered at 9.5~μm.

Highlights

Today’s commercial laser technologies routinely provide laser pulses with durations of a few tens of femtoseconds, with the most advanced laser sources delivering pulses down to the single-cycle limit [1]
Using Frequency domain Optical Parametric Amplification (FOPA) [47], two spectral slices of broadband 1.8 μm pulses are amplified in the Fourier plane
At the output of the FOPA, intrapulse difference frequency generation (DFG) is performed between two spectral slices, centered respectively at 1.7 and 1.95 μm, in a z-cut gallium selenide (GaSe) crystal whose thickness is 750 μm

Summary

Introduction

Today’s commercial laser technologies routinely provide laser pulses with durations of a few tens of femtoseconds, with the most advanced laser sources delivering pulses down to the single-cycle limit [1]. As based on HHG in solids, the signal to measure in the proposed technique is transposed to high orders of the fundamental wavelength It is naturally suited for the characterization of the relative CEP of pulses in the mid-IR range since HHG in solids can reach wavelengths towards the near-IR and the visible where ultra-sensitive spectrometers are widely available for single-shot measurements. This approach is demonstrated experimentally by measuring the CEP stability of a source that delivers mid-IR pulses centered at 9.5 μm

Experimental results for the HHG in a solid

Experimental measurement of the CEP stability

Conclusion