A simple, picojoule-sensitive ultraviolet autocorrelator based on two-photon conductivity in sapphire

TL;DR

This paper introduces a simple, sapphire-based autocorrelator capable of detecting ultrashort ultraviolet pulses with picojoule sensitivity, significantly advancing deep UV pulse measurement capabilities.

Contribution

The work presents a novel, fabricatable sapphire sensor autocorrelator that achieves unprecedented sensitivity to low-energy UV pulses without requiring a reference pulse.

Findings

Detects 2.6 pJ UV pulses with peak powers below 20 W

Achieves lowest measured autocorrelation peak powers in deep UV

Supports UV pulse lengths from 50 fs to several picoseconds

Abstract

We present a simple autocorrelator for ultraviolet pulses based on two-photon conductivity in a bench-top fabricatable sapphire sensor. We perform measurements on femtosecond 226 - 278 nm ultraviolet pulses from the third and fourth harmonics of a standard 76 MHz titanium sapphire oscillator and picosecond 266 nm pulses from the fourth harmonic of a 1064 nm 50 MHz neodymium vanadate oscillator. Our device is sensitive to 2.6 pJ ultraviolet pulses with peak powers below 20 W. These results represent the lowest measured autocorrelation peak powers by over one order of magnitude for a system with no reference pulse in the deep ultraviolet ( < 300 nm). The autocorrelator can potentially support UV pulse lengths from 50 fs - 10's of picoseconds.