Single-cycle all-fiber frequency comb

Single-cycle pulses with deterministic carrier-envelope phase enable the study and control of light-matter interactions at the sub-cycle timescale, as well as the efficient generation of low-noise multi-octave frequency combs. However, current single-cycle light sources are difficult to implement and operate, hindering their application and accessibility in a wider range of research. In this paper, we present a single-cycle 100 MHz frequency comb in a compact, turn-key, and reliable all-silica-fiber format. This is achieved by amplifying 2 $\mu$m seed pulses in heavily-doped Tm:fiber, followed by cascaded self-compression to yield 6.8 fs pulses with 215 kW peak power and 374 mW average power. The corresponding spectrum covers more than two octaves, from below 700 nm up to 3500 nm. Driven by this single-cycle pump, supercontinuum with 180 mW of integrated power and a smooth spectral amplitude between 2100 and 2700 nm is generated directly in silica fibers. To broaden applications,few-cycle pulses extending from 6 $\mu$m to beyond 22 $\mu$m with long-term stable carrier-envelope phase are created using intra-pulse difference frequency, and electro-optic sampling yields comb-tooth-resolved spectra. Our work demonstrates the first all-fiber configuration that generates single-cycle pulses, and provides a practical source to study nonlinear optics on the same timescale.Comment: Revised versio

All-fibered chalcogenide based continuous-wave parametric amplification in the mid-infrared

We demonstrate parametric amplification around 2 μm in a dispersion engineered tapered microstructured chalcogenide fiber. Almost 5 dB of signal amplification was achieved by 125 mW coupled power from a thulium-doped fiber pump laser

Fiber fuse in chalcogenide photonic crystal fibers

We observe fiber fuse in tapered GeAsSe photonic crystal fibers (PCF) at around 7 MW∕cm2 of intra-core intensity. Vertically cleaved facets from the un-tapered regions and the tapered regions were imaged. The images show shallow voids of different shapes confined to the fiber core. After longitudinally polishing a segment of the PCF, we imaged the PCF internal structure’s top view, revealing the fuse voids’ geometries and periodicity. In addition, fiber fuse was terminated in one PCF sample by a fast laser shutdown, hence saving a small segment from catastrophic damage. Four-wave-mixing was performed on this transmissive segment to estimate the dispersion. The results yielded an evident hole-pitch ratio change after fiber fuse. To our knowledge, this is the first report of fiber fuse on non-silica glass fibers and the first study of its aftermath on this un-destroyed segment of PCFs. © 2018 Optical Society of Americ

Stable 2.1 μm near 100% polarized Ho-doped all-fiber laser based on a polarizer-free cavity scheme

A highly polarized Ho-doped truly all-fibre laser was demonstrated without in-cavity polarizer. Utilizing PM-FBG and loop mirror, maximum 0.5W output power with 30% slope efficiency, 70dB ASE suppression and 99.997% degree of polarization was recorded at 2.1μ

Characterization and modeling of microstructured chalcogenide fibers for efficient mid-infrared wavelength conversion

We experimentally demonstrate wavelength conversion in the 2 μm region by four-wave mixing in an AsSe and a GeAsSe chalcogenide photonic crystal fibers. A maximum conversion efficiency of −25.4 dB is measured for 112 mW of coupled continuous wave pump in a 27 cm long fiber. We estimate the dispersion parameters and the nonlinear refractive indexes of the chalcogenide PCFs, establishing a good agreement with the values expected from simulations. The different fiber geometries and glass compositions are compared in terms of performance, showing that GeAsSe is a more suited candidate for nonlinear optics at 2 μm. Building from the fitted parameters we then propose a new tapered GeAsSe PCF geometry to tailor the waveguide dispersion and lower the zero dispersion wavelength (ZDW) closer to the 2 μm pump wavelength. Numerical simulations shows that the new design allows both an increased conversion efficiency and bandwidth, and the generation of idler waves further in the mid-IR regions, by tuning the pump wavelength in the vicinity of the fiber ZDW

MIR supercontinuum in all-normal dispersion Chalcogenide photonic crystal fibers pumped with 2μm femtosecond laser

We demonstrate mid-infrared supercontinuum generation in an all-normal dispersion Chalcogenide PCF pumped by fiber laser. The -20dB bandwidth is 1.7~2.7μm dominated by self-phase modulation and optical wave breaking. Tapering is proposed to improve performance