Nonlinear laser matter interaction in gas-filled antiresonant hollow-core fibers
Antiresonant hollow core fibers (ARHCF) are finding increasing applications in various fields of science and technology with their unique optical properties. This experimental work explores different properties of ARHCF like group velocity dispersion, polarization evolution of the propagating light. In-depth understanding of the novel features of ARHCF provides a new platform to study laser matter interaction in gas filled ARHCF. The thin glass strands that form the core of the fiber influence the effective refractive index at resonance wavelength, dependent on strand thickness. Significant variation in dispersion in the vicinity of the resonance spectral region is expected due to changing effective refractive index. This work records variation in group velocity dispersion of the fiber by few orders in magnitude near the resonance region. Deviations from the regular polygon geometry of the single-ring ARHCF core, during the fiber fabrication process, induce birefringence. This geometry-induced polarization dependence can significantly impact the ellipticity of the propagating light. The effect is more pronounced near the strand resonance wavelengths. The ARHCF with large changes the dispersion profile is filled with krypton gas at ~6 bars and pumped at 800 nm, close to resonance wavelength. This resulted in generation ofover three octave broad supercontinuum at an energy of ~23 J by accelerated fission process of soliton like waveforms when the spectral broadening due to self-phase modulation reaches the resonance wavelength. Such dynamics in a non-adiabatic dispersion regime is associated with the emission of multiple phase-matched Cherenkov radiation on both sides of the resonance, generating a multioctave-wide broadband output spectrum. The negative curvature ARHCFs which are transparent beyond the silica cut-off wavelength was used to generate 2.5 cycle pulses in the short-wave infrared wavelengths by pumping far from the resonance wavelength.
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