Broadband mid-infrared(IR)supercontinuum laser sources are essential for spectroscopy in the molecular fingerprint region.Here,we report generation of octave-spanning and coherent mid-IR supercontinua in As_(2)S_(3)-s...Broadband mid-infrared(IR)supercontinuum laser sources are essential for spectroscopy in the molecular fingerprint region.Here,we report generation of octave-spanning and coherent mid-IR supercontinua in As_(2)S_(3)-silica nanospike hybrid waveguides pumped by a custom-built 2.8μm femtosecond fiber laser.The waveguides are formed by pressure-assisted melt-filling of molten As_(2)S_(3) into silica capillaries,allowing the dispersion and nonlinearity to be precisely tailored.Continuous coherent spectra spanning from 1.1μm to 4.8μm(30 dB level)are observed when the waveguide is designed so that 2.8μm lies in the anomalous dispersion regime.Moreover,linearly tapered millimeter-scale As_(2)S_(3)-silica waveguides are fabricated and investigated for the first time,to the best of our knowledge,showing much broader supercontinua than uniform waveguides,with improved spectral coherence.The waveguides are demonstrated to be long-term stable and water-resistant due to the shielding of the As_(2)S_(3) by the fused silica sheath.They offer an alternative route to generating broadband mid-IR supercontinua,with applications in frequency metrology and molecular spectroscopy,especially in humid and aqueous environments.展开更多
文摘Broadband mid-infrared(IR)supercontinuum laser sources are essential for spectroscopy in the molecular fingerprint region.Here,we report generation of octave-spanning and coherent mid-IR supercontinua in As_(2)S_(3)-silica nanospike hybrid waveguides pumped by a custom-built 2.8μm femtosecond fiber laser.The waveguides are formed by pressure-assisted melt-filling of molten As_(2)S_(3) into silica capillaries,allowing the dispersion and nonlinearity to be precisely tailored.Continuous coherent spectra spanning from 1.1μm to 4.8μm(30 dB level)are observed when the waveguide is designed so that 2.8μm lies in the anomalous dispersion regime.Moreover,linearly tapered millimeter-scale As_(2)S_(3)-silica waveguides are fabricated and investigated for the first time,to the best of our knowledge,showing much broader supercontinua than uniform waveguides,with improved spectral coherence.The waveguides are demonstrated to be long-term stable and water-resistant due to the shielding of the As_(2)S_(3) by the fused silica sheath.They offer an alternative route to generating broadband mid-IR supercontinua,with applications in frequency metrology and molecular spectroscopy,especially in humid and aqueous environments.
