Mid-IR supercontinuum generation in birefringent, low loss, ultra-high numerical aperture Ge-As-Se-Te chalcogenide step-index fiber

Abstract

This work reports on the fabrication and subsequent supercontinuum generation in a Ge-As-Se-Te/Ge-As-Se core/clad chalcogenide step-index fiber with an elliptical-core and an ultra-high numerical aperture of 1.88 ± 0.02 from 2.5-15 µm wavelength. The fiber has very low transmission loss of < 2 dB/m from 5-11 µm and a minimum loss of 0.72 ± 0.04 dB/m at 8.56 µm. Supercontinuum spanning from 2.1 µm to 11.5 µm with an average power of ∼6.5 mW was achieved by pumping a ∼16 cm fiber with a minor/major axis core diameter of 4.2/5.2 µm with 250 fs pulses at 4.65 µm wavelength and a repetition rate of 20.88 MHz. The effect of the elliptical-core was investigated by means of mechanical rotation of the fiber relative to the linear pump polarization, and it was found to cause a shift in the supercontinuum spectral edges by several hundred nanometers.

Ultra‐large mode area mid‐infrared fiber based on chalcogenide glasses extrusion

“…19 In the normal dispersion region, SC generation exhibits significant broadening mainly due to the SPM and pump wavelength closer to the ZDW of the fiber for high efficiency. 22 High NA of 1.44 in the fiber contributes much to confine the fundamental mode light in the ultra-large core at all wavelengths, therefore, SC generation could proceed unhindered. 41 With the increase of the pumping wavelength up to 6 μm, the broadening of SC spectra is compressed, which may be due to the weakened average power of seed pulse.…”

“…The initial SC spectral broadening are firstly dominated by the self‐phase modulation (SPM), four‐wave mixing (FWM), and Raman effects in the multi‐mode fiber with large core 19 . In the normal dispersion region, SC generation exhibits significant broadening mainly due to the SPM and pump wavelength closer to the ZDW of the fiber for high efficiency 22 . High NA of 1.44 in the fiber contributes much to confine the fundamental mode light in the ultra‐large core at all wavelengths, therefore, SC generation could proceed unhindered 41 .…”

“…To the development of LMA chalcogenide fiber, most researches are focused on sulfur, 18,19 selenium, 20,21 and tellurium‐based 22,23 glasses according to their different transmission window. Wang et al 13 reported a kind of seven‐core Ge‐As‐Se‐Te fiber with each core diameter of 60 μm and NA of ~0.8, for high‐power CO 2 laser transmission, but it is difficult to couple the seven‐cores effectively and suppress its super‐mode.…”

Mid-infrared sources for biomedical applications based on chalcogenide glass fibres

“…There is a significant current research effort focused on extending the wavelength coverage towards the mid-Infrared (Mid-IR) in the 2 to 20 µm molecular fingerprint region using various chalcogenide glass compositions. Our recent work with DTU has included studies of supercontinuum sources based on the Ge-As-Se-Te glass system [16]. The aim was to exploit the highest nonlinearity and longest transmission wavelength edge in the chalcogenide glass family offered by Te-based glasses.…”

Milliwatt-Level Spontaneous Emission Across the 3.5–8 µm Spectral Region from Pr3+ Doped Selenide Chalcogenide Fiber Pumped with a Laser Diode

“…Potentially excellent candidate host glasses are chalcogenide-selenide glasses. Chalcogenide-selenide glass fibers have already proven their usefulness in the development of ultra-broadband MIR supercontinuum sources to 15 µm [9,10]. In addition, Raman lasers operating beyond 3.5 µm have been successfully realized in chalcogenide [19]).…”