Band-edge mediated frequency down-conversion in a gas-filled anti-resonant hollow-core fiber

Abstract

We demonstrate frequency down-conversions of femtosecond pulses through dispersive wave generation and degenerate four-wave mixing in a gas-filled anti-resonant hollow-core fiber. These are achieved by exploiting the rapid variation of the dispersion in the fiber’s transmission band edge. In this approach, the wavelength of the down-shifted radiation is governed solely by the thickness of the dielectric wall at the core–cladding interface, while other system parameters are accountable only for inducing sufficient nonlinear phase shifts. With the right choice of cladding wall thickness, the concept can be applied directly for generating high-power mid-infrared femtosecond pulses.

Microjoule-level mid-infrared femtosecond pulse generation in hollow-core fibres

“…It exploits the effect of the structural resonances in AR-HCF, which dominates and overrules the dispersion profile around them. The concept has been tested in a recent experiment, successfully frequency-downshifting the pump at 800 nm to 1.45 µm, i.e., to a wavelength determined by the fibre geometry [26]. Here we build on this idea to realise a fibre-based ultrafast mid-IR light source.…”

Impact of Mode-Area Dispersion on Nonlinear Pulse Propagation in Gas-Filled Anti-Resonant Hollow-Core Fiber

“…In AR-HCF, the guiding properties such as the transmission loss, dispersion, and mode-area, exhibit smooth variation across the anti-resonant (transmission) bands, while they change rapidly near the resonant wavelengths. Such characteristics have been exploited in several recent studies for generating multi-octave-spanning supercontinuum [9,10] and mediating nonlinear frequency down-conversion [11]. The rapid change in the dispersion near the resonance enables various combinations of phase-matched nonlinear frequency mixing processes to be achieved [12].…”

“…The rapid change in the dispersion near the resonance enables various combinations of phase-matched nonlinear frequency mixing processes to be achieved [12]. Moreover, since the locations of the resonances are solely determined by the cladding wall thickness, it is possible to induce emission at a desired wavelength by tailoring the cladding wall thickness [9,11].…”

Understanding the pulse propagation dynamics in gas-filled hollow-core optical waveguides

“…Therefore, they are widely applied in multioctave-spanning supercontinuum generation and wavelengthtunable dispersive wave generation [20][21][22][23][24][25]. Besides, it has one more feature that is absent in the capillary fiber-the resonance band, which has been a hot topic in recent years [26][27][28].…”

“…Due to the unique guiding mechanism, its group velocity dispersion, loss as well as effective mode area (𝐴 ) changes dramatically in the resonance regions [3]. In fact, cladding resonances in AR-HCF have been exploited in recent years for multi-octave supercontinuum generation [26,48] and frequency conversion [27]. The rapid variation of dispersion in the resonance region provides rich phase matching conditions for soliton-DW emission and four-wave mixing (FWM) process [28].…”