We experimentally demonstrate mid-infrared (MIR) supercontinuum (SC) generation spanning ∼2.0 to 15.1 μm in a 3 cm-long chalcogenide step-index fiber. The pump source is generated by the difference frequency generation with a pulse width of ∼170 fs, a repetition rate of ∼1000 Hz, and a wavelength range tunable from 2.4 to 11 μm. To the best of our knowledge, this is the broadest MIR SC generation observed so far in optical fibers. It facilitates fiber-based applications in sensing, medical, and biological imaging areas.
A rib waveguide structure in AsSe chalcogenide glass has been designed and numerically analyzed for on-chip coherent supercontinuum generation in the midinfrared region. The waveguide structure possesses an all-normal dispersion profile with dispersion value of -13.22 ps/nm·km at the pump wavelength. Coherent midinfrared supercontinuum spectrum spanning 1.2 to 7.2 μm has been obtained using a 2.5 mm long rib waveguide when pumped with 200 fs laser pulses of a peak power of 2.5 kW and a repetition rate of 1 kHz at 2.8 μm. Such highly nonlinear subwavelength size rib waveguide structures are highly applicable for the power efficient on-chip midinfrared coherent supercontinuum sources. Coherent midinfrared supercontinuum sources are very important in frequency metrology, nonlinear microscopy, nondestructive testing, molecular spectroscopy, and optical coherence tomography.
We demonstrate supercontinuum (SC) generation in a 2.8-cm-long chalcogenide double-clad fiber (Ch-DCF). The calculated chromatic dispersion of the fundamental mode shows that the Ch-DCF has flattened chromatic dispersion, which is within −10 ± 10 ps/nm/km from 3.8 to 12.6
in the normal dispersion regime. The variation of SC spectra is investigated by changing the pump wavelength and pump peak power. The broadband SC spectra extending from 2 to 14 μm at the −40 dB level is observed when the pump wavelength of 10 μm and pump peak power of 1.3 MW. The SC generation is simulated by the scalar generalized nonlinear Schrödinger equation. The simulation results are mostly the same as the experimental results and show that the supercontinua generated in the Ch-DCF are highly coherent.
For the first time, an all-solid tellurite optical glass rod with a transversely disordered refractive index profile was fabricated successfully as a medium to study the transverse localization of light and near-infrared (NIR) optical image transport. Two tellurite glass compositions of 70TeO-8LiO-17WO-3MoO-2NbO (TLWMN) and 75TeO-15ZnO-5NaO-5LaO (TZNL) which have a small difference in softening temperature (about 0.5 °C), compatible thermal expansions from room to 400 °C and broad transmission range from about 0.4 up to 6.0 µm were developed for a successful fabrication process. The tellurite transversely disordered optical rod (TDOR) consists of high and low-index units (TLWMN and TZNL, respectively). The diameter of each unit is 1.0 μm and their refractive index difference was about 0.095 at 1.55 µm. Experimental results showed that after a CW probe beam at 1.55 μm propagated in a 10-cm-long tellurite TDOR, the beam became localized. In addition, NIR optical images at 1.55 μm of numbers on a test target were transported. The captured images at the output facet of the tellurite TDOR are visually clear with high contrast and high brightness. The quality of our transported optical images can be comparable or higher than the results which were obtained by a polymer Anderson localized fiber and by a commercially available multicore imaging optical fiber.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.