Supercontinuum

About: Supercontinuum is a research topic. Over the lifetime, 7071 publications have been published within this topic receiving 127671 citations.

Supercontinuum generation in photonic crystal fibers made from highly nonlinear glasses

Abstract: The nonlinear propagation of femtosecond pulses and supercontinuum generation in photonic crystal fibers made from glasses with high nonlinear refractive indices are theoretically investigated without the use of the slowly varying envelope approximation. For specifically designed photonic crystal fibers with two zero-dispersion wavelengths, we predict supercontinuum generation due to nonsolitonic radiation emitted by the solitons on the shorter- and on the longer-wavelength sides. The physical mechanism and the peculiarities of such radiation on both spectral sides are studied and explained by the specific phase-matching relations between the solitons and their associated radiation.

Generation of isolated sub-10-attosecond pulses in spatially inhomogenous two-color fields

Abstract: We present a theoretical investigation of high-order harmonic generation in spatially inhomogeneous two-color laser fields by solving three dimensional time dependent Schrodinger equation. The cutoff in the harmonic spectra can be significantly extended by means of our proposed method (i.e., from helium interacting with the plasmon-enhanced two-color laser fields), and an ultrabroad supercontinuum up to 1.5 keV is generated by selecting proper carrier-envelope phase of the controlling field. Moreover, classical trajectory extraction, time-dependent ionization and recombination rates, and time-frequency analyses are used to explain the generation of this ultrabroadband supercontinuum. As a result, an isolated 8.8 attosecond pulse can be generated directly by the superposition of the supercontinuum harmonics.

Simultaneous dual-band ultra-high resolution optical coherence tomography

Abstract: Ultra-high resolution optical coherence tomography (OCT) imaging is demonstrated simultaneously at 840 nm and 1230 nm central wavelength using an off-the-shelf turn-key supercontinuum light source. Spectral filtering of the light source emission results in a double peak spectrum with average powers exceeding 100 mW and bandwidths exceeding 200 nm for each wavelength band. A free-space OCT setup optimized to support both wavelengths in parallel is introduced. OCT imaging of biological tissue ex vivo and in vivo is demonstrated with axial resolutions measured to be <2 µm and <4 µm at 840 nm and 1230 nm, respectively. This measuring scheme is used to extract spectroscopic features with outstanding spatial resolution enabling enhanced image contrast.

Spectral shaping of supercontinuum in a cobweb photonic-crystal fiber with sub-20-fs pulses

Abstract: Multiple approaches to generate a smooth, powerful, and stable supercontinuum in cobweb photonic-crystal fibers were undertaken by use of 18-fs pulses. These approaches include utilization of incident pulses with various chirp, power, and polarization states, as well as fibers with different lengths and core sizes. For long fibers (tens of centimeters) the supercontinuum contains a finely modulated structure that can be smoothed when the oscillator is in a regime of relaxation oscillations. Short fibers provide a supercontinuum free of gaps. By optimization of these parameters supercontinua exceeding one octave with modulations of less than 10 dB have been generated.

Super-flat coherent supercontinuum source in As 38.8 Se 61.2 chalcogenide photonic crystal fiber with all-normal dispersion engineering at a very low input energy.

Abstract: We numerically report super-flat coherent mid-infrared supercontinuum (MIR-SC) generation in a chalcogenide As38.8Se61.2 photonic crystal fiber (PCF). The dispersion and nonlinear parameters of As38.8Se61.2 chalcogenide PCFs by varying the diameter of the air holes are engineered to obtain all-normal dispersion (ANDi) with high nonlinearities. We show that launching low-energy 50 fs optical pulses with 0.88 kW peak power (corresponding to pulse energy of 0.05 nJ) at a central wavelength of 3.7 μm into a 5 cm long ANDi-PCF generates a flat-top coherent MIR-SC spanning from 2900 to 4575 nm with a high spectral flatness of 3 dB. This ultra-wide and flattened spectrum has excellent stability and coherence properties that can be used for MIR applications such as medical diagnosis of diseases, atmospheric pollution monitoring, and drug detection.