Single-shot spectra of temporally selected micropulses from a mid-infrared free-electron laser by upconversion

TL;DR

This paper presents a cost-effective method to measure single-shot spectra of temporally selected micropulses from a mid-infrared free-electron laser using upconversion and sum-frequency mixing, enabling spectral analysis at any temporal position.

Contribution

The authors demonstrate a novel, simple upconversion technique for real-time spectral measurement of MIR FEL micropulses with high temporal selectivity.

Findings

Successful upconversion of 11 μm FEL pulses to 970 nm

Ability to obtain spectra of selected micropulses at any temporal position

The system is cost-effective and compact

Abstract

We demonstrate the measurement of single-shot spectra of temporally selected micropulses from a mid-infrared (MIR) free-electron laser (FEL) by upconversion. We achieve the upconversion of FEL pulses at 11 \mu m using externally synchronized Nd:YAG or microchip laser pulses at 1064 nm to produce sum-frequency mixing (SFM) signals at 970 nm, which are detected by a compact CCD spectrometer without an intensifier. Our experimental system is very cost-effective, and allows us to obtain the laser spectra of selected micropulses at any temporal position within a single macropulse from an oscillator-type FEL.