Tunable frequency-up/down conversion in gas-filled hollow-core photonic crystal fibers

TL;DR

This paper introduces a novel method for tunable frequency conversion in gas-filled hollow-core photonic crystal fibers, leveraging the interplay of photoionization and Raman effects to achieve controllable spectral shifts.

Contribution

It demonstrates a new optical device that enables tunable frequency up/down conversion by adjusting input pulse energy and fiber pressure, combining photoionization and Raman effects.

Findings

Low energy pulses cause linear redshift due to Raman effect.

High energy pulses induce blueshift via photoionization.

Fiber pressure offers additional control over spectral shifts.

Abstract

Based on the interplay between photoionization and Raman effect in gas-filled photonic crystal fibers, we propose a new optical device to control frequency-conversion of ultrashort pulses. By tuning the input-pulse energy, the output spectrum can be either down-converted, up-converted, or even frequency-shift compensated. For low input energies, Raman effect is dominant and leads to a redshift that increases linearly during propagation. For larger pulse energies, photoionization starts to take over the frequency conversion process, and induces a strong blueshift. We have found also that the fiber-output pressure can provide an additional degree of freedom to control the spectrum shift.