Control of self-phase modulation and plasma-induced blueshifting of high-energy, ultrashort laser pulses in an argon-filled hollow fiber using conjugate pressure-gradient method (original) (raw)
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Journal of The Optical Society of America B-optical Physics, 2005
A proposal for spectral broadening of an intense laser pulse with energy 15 mJ and a pulse duration of 40 fs in an argon-filled hollow fiber, using conjugate pressure-gradient method, is presented. The design, to be referred as conjugate pressure-gradient method, shall consist of a pair of hollow-fiber segments, each with gas pressure that increasingly and decreasingly varies, respectively. It is expected that the occurrence of early self-focusing can be avoided, as well as the elimination of the additional nonlinear processes at hollow fiber exit. Simulation using 15 mJ, 40 fs laser pulses shows that, in the intensity regime where ionization is important, excellent spectral broadening and spectral phase of the pulses can be obtained using the proposed conjugate pressure gradient method. The method therefore shall be useful for the spectral broadening of high-energy, ultrashort laser pulses.
Journal of The Optical Society of America B-optical Physics, 2003
We investigate the dynamics of femtosecond laser pulses propagating in a hollow waveguide filled with argon using a simulation model based on the 3D nonlinear Schrödinger equation (NLSE). The results show that if the intensity is low and no ionization takes places, the spatial profile of the beam does not change such that its propagation model may be reduced to simply a 1D model. On the other hand, if the intensity is high and in the presence of ionization, the spatial dynamics as well as temporal dynamics of the propagation become very complicated. By further elaborating the propagation dynamics, it was found that the self-focusing and plasma defocusing are the origin of the complicated structure of the spatio-temporal intensity profiles.
Generation of 50 fs, 50 mJ pulses at 1 kHzusing hollow-fiber pulse compression
Optics Letters, 2010
We demonstrate methods to increase the energy incident on hollow fibers for spectral broadening by self-phase modulation. We used chirped pulses for spectral broadening, lowering the optical intensity to avoid ionization of the gaseous medium. We also used helium as a nonlinear medium and demonstrated the generation of 5:0 fs, 5:0 mJ pulses at a repetition rate of 1 kHz using a pressure gradient hollow-fiber pulse compressor.
Optical pulse compression of ultrashort laser pulses in a multi-hollow-core fiber
Optics Communications, 2012
We investigate the possibility of optical pulse compression of high energy ultrashort laser pulses in an argon-filled planar waveguide, based on two level coupled mode theory and the full 3D nonlinear Schrödinger equation. We derive general expressions for controlling the spatial beam profile and the extent of the spectral broadening. The analysis and simulations suggest that the proposed method should be appropriate for optical pulse compression of ultrashort laser pulses with energies as high as 600 mJ.
Single-shot dynamics of pulses from a gas-filled hollow fiber
Applied Physics B-lasers and Optics, 2004
We present measurements of the performance characteristics of few-cycle laser pulses generated by propagation through a gas-filled hollow fiber. The pulses going into the fiber and the compressed pulses after the fiber were simultaneously fully characterized shot-by-shot by using two kHz SPIDER setups and kHz pulse energy measurements. Output-pulse properties were found to be exceptionally stable and pulse characteristics relevant for non-linear applications like high-harmonic generation are discussed.
High-energy ultrashort laser pulse compression in hollow planar waveguides
Optics Letters, 2009
We demonstrate compression of high energy ultrashort laser pulses by nonlinear propagation inside gas-filled planar hollow waveguides. We adjust the input beam size along the non-guiding dimension of the planar waveguide to restrain the intensity below photoionization, while the relatively long range guided propagation yields significant selfphase modulation (SPM) and spectral broadening. We compare the compression in different noble gases and obtain 13.6 fs duration with output pulse energy of 8.1 millijoule (mJ) in argon, and 11.5 fs duration with 7.6 mJ energy in krypton. The broadened spectra at the output of the waveguide are uniform over more than 70% of the total pulse energy. Shorter duration could be obtained at the expense of introduction of spatial structure in the beam (and eventual formation of filaments) resulting from small-scale self focusing in the non-guided direction.
Carrier-envelope phase stability of hollow fibers used for high-energy few-cycle pulse generation
Optics Letters, 2013
We investigated the carrier-envelope phase (CEP) stability of a hollow-fiber setup used for highenergy, few-cycle pulse generation. Saturation of the output pulse energy is observed at 0.6 mJ for a 260 µm inner-diameter, 1 m long fiber, statically filled with neon, with the pressure adjusted to achieve an output spectrum capable of supporting sub-4 fs pulses. The maximum output pulse energy can be increased to 0.8 mJ by using either differential pumping, or circularly polarized input pulses. We observe the onset of an ionization-induced CEP instability, which does not increase beyond an input pulse energy of 1.25 mJ due to losses in the fiber caused by ionization. There is no significant difference in the CEP stability with differential pumping compared to static-fill, demonstrating that gas flow in differentially pumped fibers does not degrade the CEP stabilization.
European Physical Journal-special Topics, 2009
The compression of laser pulses at 527 nm, 250 fs long, down to 30 fs is reported. The laser pulses, originated from a frequency-doubled, mode-locked Nd:glass laser, were compressed by a 0.7-m-long, 150-μ m-bore-diameter argon-filled hollow fiber and a pair of SF10 prisms with a final energy of 160 μJ. These are the shortest, high energy pulses ever produced by direct pulse compression at the central wavelength of 527 nm. The spectral broadening of the pulses propagating inside the hollow fiber was experimentally examined for various filling-gas pressures and input pulse energies. The physical limitations of the hollow-fiber pulse compression technique applied in the visible range are also studied. An application to laser ablation of Ni target is performed. Metal nanoparticles are obtained both with the 250-fs and with the 30-fs pulse.
Optics Express, 2014
Spectral broadening in gas-filled hollow-core fibers is discussed for sulfur hexafluoride, a molecular gas with Raman activity. Experimental results for compressed pulses are presented for input pulses longer than the Raman period and shorter than the dephasing time at a central wavelength of 800 nm and 400 nm, respectively. For both wavelengths we compress the pulses by a factor of three and maintain a good pulse quality. The obtained results are of interest for compressing pulses generated with Yb doped lasers.