Flexible delivery of broadband, 100-fs mid-infrared pulses in the water-absorption band using hollow-core photonic crystal fibre

TL;DR

This paper demonstrates the use of evacuated hollow-core photonic crystal fibre to flexibly transmit ultrafast mid-infrared pulses over several meters with high fidelity, overcoming limitations of traditional methods.

Contribution

It introduces a low-loss, water-absorption-band engineered hollow-core PCF capable of delivering high-quality mid-IR pulses over meters without complex vacuum setups.

Findings

Successful transmission of 100 fs pulses over 5 meters

Preservation of spatial, spectral, and temporal fidelity

Superior performance compared to free-space and air-filled PCF

Abstract

High quality free-space and over-fibre transmission of mid-IR light is limited by factors such as material-related absorption, diffraction, light leakage and nonlinearity. Conventional vacuum apparatus can be utilized for high-quality laser-beam delivery to address these issues, the deployment of such apparatus would, however, increase the system complexity, being detrimental to their practical applications. Here we report the successful use of evacuated hollow-core photonic crystal fibre (PCF) to flexibly transmit ultrafast mid-IR pulses over several meters, while preserving exceptional spatial, spectral and temporal fidelity. The PCF was engineered to feature a low-loss transmission band within the water absorption range, and an evacuated 5-m length was used to transmit Watt-level, 100 fs pulses centred at around 2.8 microns. A comparison between free-space transmission and air-filled PCF highlights the superior performance of the evacuated hollow-core PCF, indicating its strong suitability for the flexible delivery of sub-ps laser pulses in the mid-IR.