Non-silica microstructured optical fibers for mid-IR supercontinuum generation from 2 μm - 5 μm

Abstract

We have performed numerical simulations to investigate the optimization of compound glass microstructured optical fibers for mid IR supercontinuum generation beyond the low loss transmission window of silica, using pump wavelengths in the range 1.55-2.25 µm. Large mode area fibers for high powers, and small core fiber designs for low powers, are proposed for a variety of glasses. Modeling results showed that for Bismuth and lead oxide glasses, which have nonlinearities ~10 x that of silica, matching the dispersion profile to the pump wavelength is essential. For chalcogenide glasses, which have much higher nonlinearities, the dispersion profile is less important. The pump pulses have duration of <1 ps, and energy <30 nJ. The fiber lengths required for generating continuum were <40 mm, so the losses of the fibers were not a limiting factor. Compared to planar rib-waveguides or fiber-tapers, microstructured fiber technology has the advantages of greater flexibility for tailoring the dispersion profile over a broad wavelength span, and a much wider possible range of device lengths.

Mid-IR Supercontinuum Generation From Nonsilica Microstructured Optical Fibers

“…However, we note that 0-6 THz is an important frequency range because the frequency width [full-width at half-maximum (FWHM)] for a 200-fs transform-limited Gaussian pulse is 2.2 THz, and it is, therefore, this part of the Raman spectrum that provides the long wavelength gain for soliton self-frequency shifting (SSFS). In our previous study of multicomponent glass MOFs, we showed the spectra from simulations performed for Bi glass WW fiber for the same seed pulse parameters and with: 1) SPM term only; 2) SPM and self-steepening terms; and 3) including the Raman response [10]. The overall shape of the continuum was similar in all cases, and we concluded that the initial continuum generation is not highly dependent on the Raman response in the fiber.…”

“…1(b). In the small-core Bi MOF simulations, we fixed the pulse energy at 1 nJ, T 0 = 0.2 ps (FWHM), and fiber length to be equal to 40 mm, as this combination was found to be suitable for demonstrating supercontinuum in our earlier study [10]. As described in Section IV-C, for the large-mode fiber simulations, the seed pulse energy was increased to 30 nJ.…”

“…In a previous conference paper, we presented the results of numerical simulations to indicate the optimum glass-type and fiber-design combinations for mid-IR supercontinuum generation when pumped at near-IR wavelengths by systematically varying each fiber parameter with other parameters held constant [10]. We established that for 200-fs near-IR seed pulses, the continuum was generated in < 40-mm fiber lengths.…”

Nanotube–Polymer Composites for Ultrafast Photonics

“…Due to the wide gain bandwidth of Tm-doped and Tm-Ho co-doped laser systems, sub-100 fs pulse trains at 2 mm can be efficiently generated using all-solid-state diode-pumped technology. Short mode-locked pulse trains in this spectral region are of major interest in time-resolved molecular spectroscopy, IR supercontinuum REVIEW www.advmat.de generation, [57] and frequency metrology. Moreover, high-energy ultrashort pulses at $2 mm find specific applications in highorder harmonic and high-efficiency soft-X-ray generation [58] and for optical relativistic effects.…”

Nonlinear soft oxide glasses for microstructured optical fibers development

“…Recently a number of works devoted to soft glass based PCFs are reported 3,[5][6][7][8][9][10] . The nonlinear refractive index of some of these glasses is up to few hundred times higher than in the case of standard silica glass and its transmission window goes up to 15μm 6 .…”