Supercontinuum (SC) generation based on ultrashort pulse compression constitutes one of the most promising technologies towards ultra-wide bandwidth, high-brightness, and spatially coherent light sources for applications such as spectroscopy and microscopy. Here, multi-octave SC generation in a gas-filled hollow-core antiresonant fiber (HC-ARF) is reported spanning from 200 nm in the deep ultraviolet (DUV) to 4000 nm in the mid-infrared (mid-IR) having an output energy of 5 μJ. This was obtained by pumping at the center wavelength of the first anti-resonant transmission window (2460 nm) with ~100 fs pulses and an injected pulse energy of ~8 μJ. The mechanism behind the extreme spectral broadening relies upon intense soliton-plasma nonlinear dynamics which leads to efficient soliton self-compression and phase-matched dispersive wave (DW) emission in the DUV region. The strongest DW is observed at 275 nm which corresponds to the calculated phase-matching wavelength of the pump. Furthermore, the effect of changing the pump pulse energy and gas pressure on the nonlinear dynamics and their direct impact on SC generation was investigated. This work represents another step towards gas-filled fiber-based coherent sources, which is set to have a major impact on applications spanning from DUV to mid-IR.

Deep-UV (DUV) supercontinuum (SC) sources based on gas-filled hollow-core fibers constitute perhaps the most viable solution towards ultrafast, compact, and tunable lasers in the UV spectral region. Noise and spectral stability of such broadband sources are key parameters that define their true potential and suitability towards real-world applications. In order to investigate the spectral stability and noise levels in these fiber-based DUV sources, we generate an SC spectrum that extends from 180 nm (through phasematched dispersive waves -DWs) to 4 μm by pumping an argon-filled hollow-core anti-resonant fiber at a wavelength of 2.45 μm. We characterize the long-term stability of the source over several days and the pulse-to-pulse relative intensity (RIN) noise of the strongest DW at 275 nm. The results indicate no sign of spectral degradation over 110 hours, but the RIN of the DW pulses at 275 nm is found to be as high as 33.3%. Numerical simulations were carried out to investigate the spectral distribution of the RIN and the results confirm the experimental measurements and that the poor noise performance is due to the RIN of the pump laser, which was hitherto not considered in numerical modelling of these sources. The results presented herein provide an important step towards an understanding of the noise mechanism underlying such complex light-gas nonlinear interactions and demonstrate the need for pump laser stabilization. ABSTRACTThis document provides supplementary information to "Noise and spectral stability of deep-UV gas-filled fiber-based supercontinuum sources". Here we provide the details of the phase-matching conditions between the soliton and dispersive waves, and compared our expression to other expressions mentioned in the manuscript. Additionally, we provide he figures for filtered DUV used for the RIN measurements as well as the histograms of the RINs for the pump laser, Ti:sapphire, and DUV at 360 nm and 280 nm. We further compared the coherence and RINs when the pump laser noise is not considered and when considered.

In this Letter, we demonstrate a high pulse energy and linearly polarized mid-infrared Raman fiber laser targeting the strongest absorption line of C O 2 at ∼ 4.2 µ m . This laser was generated from a hydrogen ( H 2 )-filled antiresonant hollow-core fiber, pumped by a custom-made 1532.8 nm Er-doped fiber laser delivering 6.9 ns pulses and 11.6 kW peak power. A quantum efficiency as high as 74% was achieved, to yield 17.6 µJ pulse energy at 4.22 µm. Less than 20 bar H 2 pressure was required to maximize the pulse energy since the transient Raman regime was efficiently suppressed by the long pump pulses.

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Development of novel mid-infrared (MIR) lasers could ultimately boost emerging detection technologies towards innovative spectroscopic and imaging solutions. Photoacoustic (PA) modality has been heralded for years as one of the most powerful detection tools enabling high signal-to-noise ratio analysis. Here, we demonstrate a novel, compact and sensitive MIR-PA system for carbon dioxide (CO2) monitoring at its strongest absorption band by combining a gas-filled fiber laser and PA technology. Specifically, the PA signals were excited by a custom-made hydrogen (H2) based MIR Raman fiber laser source with a pulse energy of ⁓ 18 μJ, quantum efficiency of ⁓ 80% and peak power of ⁓ 3.9 kW. A CO2 detection limit of 605 ppbv was attained from the Allan deviation. This work constitutes an alternative method for advanced high-sensitivity gas detection.

In this work, we present a high pulse energy multiwavelength Raman laser spanning from 1.53 µm up to 2.4 µm by employing the cascaded rotational stimulated Raman scattering (SRS) effect in a 5-m hydrogen (H2)filled nested anti-resonant fiber (NARF), pumped by a linearly polarized Er/Yb fiber laser with a peak power of ~13 kW and pulse duration of ~7 ns in the C-band. The developed Raman laser has distinct lines at 1683 nm, 1868 nm, 2100 nm, and 2400 nm, with pulse energies as high as 18.25 µJ, 14.4 µJ, 14.1 µJ, and 8.2 µJ, respectively. We demonstrate how the energy in the Raman lines can be controlled by tuning the H2 pressure from 1 bar to 20 bar.

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A hollow-core anti-resonant fiber (HC-ARF) design based on hybrid silica/silicon cladding is proposed for single-polarization, single-mode and high birefringence. We show that by adding silicon layers in a semi-nested HC-ARF, one of the polarization states can be strongly suppressed while simultaneously maintaining low propagation loss for other polarization states, single-mode and high birefiringence. The optimized HC-ARF design exhibits propagation loss, high birefringence, and polarization-extinction ratio of 0.05 dB/m, 0.5 × 10−4, >300 respectively for y-polarization while the loss of x-polarization is >5 dB/m at 1064 nm. The fiber also has low bend-loss and thus can be coiled to a small bend radii of 5 cm having ≈0.06 dB/m bend loss.