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Highlights:As-Se tapered suspended-core fibers were designed for mid-IR SC generation. Parameters of the produced fibers were studied experimentally and numerically. SC in the 1-10 μm range with 150-fs 100-pJ pump at 2 μm was obtained numerically. Experiments on spectral broadening of pump pulses at 1.57 μm were performed. AbstractWe designed and developed tapered suspended-core fibers of high-purity As 39 Se 61 glass for supercontinuum generation in the mid-IR with a standard fiber laser pump source at 2 μm. It was shown that microstructuring allows shifting a zero dispersion wavelength to the range shorter than 2 μm in the fiber waist with a core diameter of about 1 μm. In this case, supercontinuum generation in the 1-10 μm range was obtained numerically with 150-fs 100-pJ pump pulses at 2 μm. We also performed experiments on wavelength conversion of ultrashort optical pulses at 1.57 μm from Er: fiber laser system in the manufactured As-Se tapered fibers. The measured broadening spectra were in a good agreement with the ones simulated numerically. IntroductionThe mid-infrared (IR) supercontinuum (SC) laser sources have important applications in both basic science and industry. These light sources are often based on ultra-broadband nonlinear spectral conversion in fluoride, tellurite, and chalcogenide glass (ChG) fibers [1][2][3][4]. Among different glass compositions, the ChGs have the highest nonlinearity and the broadest transparency ranges which allow operating at wavelengths where fluoride and tellurite glasses cannot be transparent [1]. To date, the broadest SC demonstrated in ChG fibers extends from ~2 to 16 μm [4]. It is well-known that not only the nonlinearity and transparency range impact on spectral broadening; the zerodispersion wavelength (ZDW) location with respect to a central pump wavelength is also of great importance for SC width [5,6]. Operation in the anomalous dispersion regime often allows obtaining a broader spectrum in comparison with normal dispersion. In this pumping scheme, SC generation is dominated by the soliton dynamics. To generate ultra-broadband SC in solid step-index ChG fibers having ZDW near the material ZDW (which is significantly beyond 4 μm, for example, 4.81 μm for As 2 S 3 , 7.5 μm for As 2 Se 3 , and >7.5 μm for Te-based ChG [1]), mid-IR optical parametric oscillators and amplifiers have been employed [7,8]. However, if it is desirable to use a pump source at shorter wavelengths than material ZDW, microstructured or/and tapered fibers with blue-shifted ZDW can be implemented. Suspended-core fiber (SCF) geometry is widespread for dispersion management. So, SC spanning 1.7-7.5 μm has been obtained in As-Se SCF with ZDW of 3.5 μm pumped at 4.4 μm [9]. In this paper, the design, development, and manufacturing of tapered SCF with a thin waist core diameter of about 1 μm of the high-purity As-Se glass are reported. The As-Se glass has a broad spectral transparency range (0.85-17.5 μm for absorption coefficient level of 1 cm

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We report on efficient supercontinuum generation in tapered suspended-core A s 39 S e 61 fibers pumped by a femtosecond mode-locked Cr:ZnSe laser. The supercontinuum spectrum spans the mid-infrared spectral region from 1.4 to 4.2 µm, and its spectral coherence is proved by heterodyning with a single-frequency narrow-linewidth Er-fiber laser at 1.55 µm, measuring a beat note with 27-dB signal-to-noise ratio in a resolution bandwidth of 100 kHz. The intensity stability of the supercontinuum radiation is also characterized by relative intensity noise measurements.