High-power, ultra-broadband supercontinuum light generated in a single-mode fiber pumped with a nanosecond passively Q-switched microchip laser.

The compact, high-power, broadband continuum sources are extremely needed for developing portable instruments for various applications such as optical coherence tomography, high-resolution spectroscopy, and so on. Here, we develop a compact high-power, ultra-broadband supercontinuum (SC) light source in a single-mode fiber (SMF) pumped with a Yb:YAG/Cr4+:YAG passively Q-switched microchip laser oscillating at 1030 nm. The spectral bandwidth of the SC light is over 1150 nm covering from 600 to 1750 nm. The maximum average output power is 181.8 mW at an input pump power of 880 mW. The optical efficiency is 20.6%, and the net conversion efficiency is as high as 51.6% with respect to the pump power coupled into the fiber. The ultra-broadband spectrum of the SC generated in the SMF is caused by the intermodal four-wave mixing (IMFWM) and cascade stimulated Raman scattering effects. Various transverse modes have been experimentally observed in SC beam generated in the SMF. Wavelength-dependent transverse modes propagating in the SMF participating in the IMFWM process dramatically expand the spectral range in the visible region. The experimental results are basically consistent with the theoretical simulations of broadband SC generated in the SMF through the IMFWM process.

1.5-14 µm midinfrared supercontinuum generation in a low-loss Te-based chalcogenide step-index fiber.

We have experimentally demonstrated midinfrared (MIR) supercontinuum (SC) generation in a low-loss Te-based chalcogenide (ChG) step-index fiber. The fiber, fabricated by an isolated extrusion method, has an optical loss of 2-3 dB/m at 6.2-10.3 µm and 3.2 dB/m at 10.6 µm, the lowest value reported for any Te-based ChG step-index fiber. A MIR SC spectrum (∼1.5 to 14 µm) is generated from the 23-cm fiber pumped by a 4.5 µm laser (∼150 fs, 1 kHz). To the best of our knowledge, this is the first SC experimental demonstration in Te-based ChG fiber and the broadest MIR SC generation pumped in the normal dispersion regime in the optical fibers.

Novel Ge-Ga-Te-CsBr glass system with ultrahigh resolvability of halide.

CO2 molecule, one of the main molecules to create new life, should be probed accurately to detect the existence of life in exoplanets. The primary signature of CO2 molecule is approximately 15 µm, and traditional S- and Se-based glass fibers are unsuitable. Thus, Te-based glass is the only ideal candidate glass for far-infrared detection. In this study, a new kind of Te-based chalcohalide glass system was discovered with relatively stable and large optical band gap. A traditional melt-quenching method was adopted to prepare a series of (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glass samples. Experiment results indicate that the glass-forming ability and thermal properties of glass samples were improved when CsBr was added in the host of Ge-Ga-Te glass. Ge-Ga-Te glass could remarkably dissolve CsBr content as much as 85 at.%, which is the highest halide content in all reports for Te-based chalcohalide glasses. Moreover, ΔT values of these glass samples were all above 100 °C. The glass sample (Ge15Ga10Te75)65 (CsBr)35 with ΔT of 119 °C was the largest, which was 7 °C larger than that of Ge15Ga10Te75 host glass. The infrared transmission spectra of these glasses show that the far-infrared cut-off wavelengths of (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glasses were all beyond 25 µm. In conclusion, (Ge15Ga10Te75)100-x (CsBr)x chalcogenide glasses are potential materials for far-infrared optical application.