Abstract
In this study, the supercontinuum (SC) generation in a 1-m-long As2S3 fiber with a 200 μm core diameter was demonstrated experimentally. The high-purity As2S3 fiber we used exhibited very low optical loss with a background loss of approximately 0.1 dB/m at a wavelength of 2-5 μm. SC generation was studied by pumping the fiber at different wavelengths and different peak powers. A strong spectral broadening with a 30 dB spectral flatness spanning from 1.4 to 7.0 µm was obtained when the fiber was pumped with 150 fs short pulses at 5.0 µm. The SC generation in bent fiber was also studied. The result showed that the bending radius of the fiber will significantly affect the SC spectra bandwidth and the output power. The SC spectra in the used fiber could still be maintained when it was bent to a radius of 5 cm.
Highlights
Recent years have seen a growing interest in producing broadband supercontinuum (SC) sources in mid-infrared (MIR) regions for several applications [1, 2], such as biomedical sensing [3], metrology [4], spectroscopy [5], optical tomography [6], and microscopy [7]
SC generation was studied by pumping the fiber at different wavelengths and different peak powers
A strong spectral broadening with a 30 dB spectral flatness spanning from 1.4 to 7.0 μm was obtained when the fiber was pumped with 150 fs short pulses at 5.0 μm
Summary
Recent years have seen a growing interest in producing broadband supercontinuum (SC) sources in mid-infrared (MIR) regions for several applications [1, 2], such as biomedical sensing [3], metrology [4], spectroscopy [5], optical tomography [6], and microscopy [7]. The typical route to achieve a broadband SC source involves sending ultrafast laser pulses into dispersion-engineered MIR transparent fibers. Chalcogenide glass fibers are excellent candidates for broadband SC generation because of their excellent MIR transparency and high thirdorder nonlinearity [1, 9]. Tapered and suspended-core chalcogenide fibers, which allow enhanced nonlinearity and dispersion engineering, have been successfully demonstrated for low-threshold, octave-spanning SC sources in near-infrared (NIR) and MIR regions. Except for the factors of dispersion and transmission losses, most SC generation based on tapered and suspended-core chalcogenide fibers are limited to 1–5 μm spectral region by pumping with NIR sources, which are far from the transmission limit of these materials [19,20,21,22,23]. A long pump wavelength is essential to extend the SC spectrum to a wavelength of ∼10 μm [28,29,30,31]
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