Visible supercontinuum generation through hollow beams in a two-mode photonic crystal fiber

Abstract

We achieve supercontinuum generation in the visible spectral regime through hollow beams in a two-mode photonic crystal fiber (TM-PCF). The TM-PCF is pumped with 532 nm sub-nanosecond pulses and it supports only the fundamental and second-order modes over the entire visible region. By two-mode excitation and nonlinear propagation, polychromatic hollow beams are generated in two separate spectral regions, which lead to a "white" hollow beam at the fiber output. We have also identified the efficient anti-Stokes conversion in the deeply normal dispersion regime as an intermodal phase-matched process, which can be employed for the blue extension of visible and ultraviolet supercontinuum.

Infrared supercontinuum frequency doubling via nonlinear Raman-Nath and Cerenkov scattering processes

“…PCFs have found growing applications as components of larger-scale laser systems and optical devices for a broad variety of applications, including frequency comb metrology, attosecond science, and optical parametric amplification of few-cycle field waveforms. SC light sources based on PCF are usually designed to provide a flat spectrum over a wide wavelength range, from infrared to visible and also UV [7,8]. Nevertheless, the SC spectrum directly depends on several parameters such as the fiber material and structure, the fiber length, the pump power and central wavelength; thus the shaping of the PCF spectrum may become difficult, especially in UV and far-infrared domains where absorption of silica fibers is high.…”

Monolithic all-fiber mid-infrared supercontinuum source based on a step-index two-mode As2S3 fiber*

“…Compared with the fundamental mode, HOMs exhibit different dispersion curves and nonlinear indices, which are the most important factors for SC generation. In addition, intermodal nonlinear effects taken place through cross-phase modulation, [13] four-wave mixing [14,15] and stimulated Raman scattering, [16] offer an additional possibility for spectral broadening through new degrees of freedom. Hence, it is necessary to investigate HOM SC generation in few-mode chalcogenide fibers.…”

Characterization of spectral broadening and contrast enhancement in cross-polarized wave generation based on gadolinium gallium garnet crystal

“…19) Many techniques have been developed for broadband seed pulse generation, such as the self-mode-lock Ti:sapphire oscillator, 20) the SPM-based spectrum broadening in multipass cell 21) and supercontinuum (SC) generation by focusing high-intense laser through nonlinear media, including the bulk media, 22) the conventional fiber 8) and the photonic crystal fiber (PCF). 23,24) However, the pulses for SC generation usually have to be focused for high intensity and injected into the few-micrometer-diameter structure, which is difficult for the experimental operation and can easily lead to beam quality deterioration. Besides, the input pulse noise in current SC generations can easily induce shot-to-shot intensity fluctuations and phase fluctuations, which could respectively wash out the spectral fine structure and lead to the SC coherence degradation.…”