Abstract
We show numerically that ultra-short pulses can be generated in the mid-infrared when a gas filled hollow-core fiber is pumped by a fundamental pulse and its second harmonic. The generation process originates from a cascaded nonlinear phenomenon starting from a spectral broadening of the two pulses followed by an induced phase-matched four wave-mixing lying in the mid-infrared combined with a dispersive wave. By selecting this mid-infrared band with a spectral filter, we demonstrate the generation of ultra-short 60 fs pulses at a 3–4 µm band and a pulse duration of 20 fs can be reached with an additional phase compensator.
Highlights
In recent years, there has been growing interest in mid-infrared (MIR) sources driven by demanding applications such as gas sensing [1], food inspection [2], life and molecular sciences [3] or the creation of secondary sources [4]
We propose to generate ultra-short pulses in the MIR by pumping a gas-filled hollow-core photonic crystal fiber (HC-PCF) with two different pulses to create an efficient phase-matched process
Outstanding progress has been achieved to reduce the loss of HC-PCFs in the MIR [10,11], for example, with a transmission loss of ~25–50 dB/km being obtained by minimizing the interaction between the core guided mode and the silica walls of the cladding of an inhibited-coupling hollow-core fiber [10]
Summary
There has been growing interest in mid-infrared (MIR) sources driven by demanding applications such as gas sensing [1], food inspection [2], life and molecular sciences [3] or the creation of secondary sources [4]. Alternative devices at lower power are based on other transparent materials such as in silicon-, lithium niobate- or chalcogenide-based waveguides [5,6,7] or specific nonlinear fibers with soft-glass materials [8] In this manuscript, we propose to generate ultra-short pulses in the MIR by pumping a gas-filled hollow-core photonic crystal fiber (HC-PCF) with two different pulses to create an efficient phase-matched process. Anti-resonant HC-PCFs have gained interest [12] due to their properties, including a wide tunability of the spectral transmission bands from the ultra-violet (UV) to MIR [13,14,15] with low loss, high damage threshold [16] and a single mode propagation by choosing specific geometries [17]. The effective area Aeff ~992 μm was calculated from the model [22] and was assumed constant for the spectral range
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