J. Darginavičius

Ultrabroadband supercontinuum and third-harmonic generation in bulk solids with two optical-cycle carrier-envelope phase-stable pulses at 2 μm

We report on the generation of ultrabroadband supercontinuum (SC) by filamentation of two optical-cycle, carrier-envelope phase-stable pulses at 2 μm in fused silica, sapphire, CaF₂ and YAG. The SC spectra extend from 450 nm to more than 2500 nm, and their particular shapes depend on dispersive properties of the materials. Prior to spectral super-broadening, we observe third-harmonic generation, which occurs in the condition of large phase and group velocity mismatch and consists of free and driven components. A double-peaked third-harmonic structure coexists with the SC pulse as demonstrated by the numerical simulations and verified experimentally. The SC pulses have stable carrier envelope phase with short-term rms fluctuations of ∼ 300 mrad, as simultaneously measured in YAG crystal by f-2f and f-3f interferometry, where the latter makes use of intrinsic third-harmonic generation.

Generation of carrier-envelope phase-stable two optical-cycle pulses at 2 μm from a noncollinear beta-barium borate optical parametric amplifier

We report on the generation of two optical-cycle, carrier-envelope phase-stable pulses with energy of 15 μJ at central wavelength of 2 μm. Pulses of 15 fs (2.3 optical cycles) duration are obtained by difference-frequency generation, which at the same time provides passive carrier-envelope phase stabilization, and noncollinear optical parametric amplification in beta-barium borate crystal, which is shown to provide broad phase-matching bandwidth if seeded by pulses in the 1.6-2.6 μm wavelength range. Pulse compression is achieved by means of a simple propagation through the optical setup and by precisely controlling the initial chirp of the pulses to be frequency downconverted.

Generation of 30-fs ultraviolet pulses by four-wave optical parametric chirped pulse amplification.

We report on the generation of approximately 30-fs ultraviolet pulses with approximately 10 microJ energy by means of four-wave optical parametric chirped pulse amplification in fused silica. The four-wave optical parametric amplifier is pumped by the second-harmonic of the Ti:sapphire laser and is seeded by visible broadband chirped signal pulses. The idler pulses are produced in the ultraviolet by four-wave mixing and are compressed in a medium with normal group velocity dispersion.

Generation of broadly tunable sub-30-fs infrared pulses by four-wave optical parametric amplification

We report on the generation of sub-30-fs near-IR light pulses by means of broadband four-wave parametric amplification in fused silica. This is achieved by frequency downconversion of visible broadband pulses provided by a commercial blue-pumped beta-barium borate crystal-based noncollinear optical parametric amplifier. The proposed method produces the IR idler pulses with energy up to ∼20 μJ and tunable in wavelength from 1 to 1.5 μm. The shortest pulse duration is 17.6 fs, measured at 1.2 μm.

Generation and amplification of ultraviolet light pulses by means of parametric four‐wave interactions in transparent solid‐state media

We experimentally demonstrate efficient generation of the ultrashort ultraviolet light pulses by means of phase‐matched four‐wave optical parametric amplification and four‐wave difference frequency mixing in wide bandgap solids with cubic nonlinearity. Broadband four‐wave optical parametric amplification around 330 nm is achieved in optically isotropic fused silica and CaF2 crystals, suggesting amplification bandwidth of ∼20 nm that is able supporting ultraviolet light pulses as short as 7.5 fs (in the transform limit). Efficient generation of 3‐rd (351 nm), 5‐th (211 nm), and 6‐th (176 nm) harmonics with 1‐ps pulses of the Nd:glass laser is experimentally demonstrated through non‐collinearly phase‐matched four‐wave difference‐frequency mixing in fused silica, CaF2 and MgF2 crystals.

Efficient ultrafast four-wave optical parametric amplification in condensed bulk media

Efficient four-wave optical parametric amplification in bulk fused silica is demonstrated under mJ-pumping in the ultrashort pulse regime by means of cylindrical beam focusing and non-collinear phase matching geometry without onset of filamentation and optical damage. We experimentally show that the developed four-wave optical parametric amplification scheme is able to support sub-10 fs pulses in the near infrared and in the ultraviolet spectral region.