Fiber-based biphoton source with ultrabroad frequency tunability

TL;DR

This paper presents a tunable biphoton source using xenon-filled hollow-core photonic crystal fiber, achieving large frequency shifts by adjusting gas pressure, enabling applications requiring widely separated photon pairs.

Contribution

The work introduces a gas-pressure controlled tunable biphoton source that overcomes solid-core fiber limitations, with record tunability and broad bandwidths for quantum applications.

Findings

Maximum tunability of 120 THz achieved

Photon pairs separated by more than one octave at 21 bar

Both photons maintain large bandwidths despite wide frequency separation

Abstract

Tunable biphotons are highly important for a wide range of quantum applications. For some applications, especially interesting are cases where two photons of a pair are far apart in frequency. Here, we report a tunable biphoton source based on a xenon-filled hollow-core photonic crystal fiber. Tunability is achieved by adjusting the pressure of the gas inside the fiber. This allows us to tailor the dispersion landscape of the fiber, overcoming the principal limitations of solid-core fiber-based biphoton sources. We report a maximum tunability of 120 THz for a pressure range of 4 bar with a continuous shift of 30 THz/bar. At 21 bar, the photons of a pair are separated by more than one octave. Despite the large separation, both photons have large bandwidths. At 17 bar, they form a very broad (110 THz) band around the frequency of the pump.