Few-cycle pulse retrieval using amplitude swing technique.

Ultrashort pulses have garnered significant attention across various scientific disciplines and applications. In this paper, we demonstrate that the recently introduced amplitude swing technique is a robust method for characterizing pulses in the few-cycle temporal domain by analyzing compressed and chirped pulses from a Ti:Sapphire laser oscillator. The duration of the measured pulse for the case of best compression was 5.

Characterization of ultrashort vector pulses from a single amplitude swing measurement.

Ultrashort vector pulses exhibit time- and frequency-dependent polarization, sparking significant interest across various fields. Simple, robust, and versatile characterization techniques are crucial to meet this rising demand. Our study showcases how complete polarization dynamics are encoded within a single amplitude swing trace, demonstrated both theoretically and experimentally.

Generalizing amplitude swing modulation for versatile ultrashort pulse measurement.

In this work we broaden the amplitude modulation concept applied to the temporal characterization of ultrashort laser pulses with the amplitude swing technique. We theoretically study the effect of diverse types of relative amplitude and phase modulations. This variation of the replicas can be implemented by means of rotating zero-order waveplates to manipulate the delayed pulse replicas produced in a following multi-order waveplate, which can be more practical under certain conditions.

Dynamical behaviour of ultrathin [CoFeB (t)/Pd] films with perpendicular magnetic anisotropy.

CoFeB-based ultrathin films with perpendicular magnetic anisotropy are promising for different emerging technological applications such as nonvolatile memories with low power consumption and high-speed performance. In this work, the dynamical properties of [CoFeB (t)/Pd (10 Å)] multilayered ultrathin films (1 Å ≤ t ≤ 5 Å) are studied by using two complementary methods: time-resolved magneto-optical Kerr effect and broadband ferromagnetic resonance. The perpendicular magnetization is confirmed for multilayers with t ≤ 4 Å.

Robustness and capabilities of ultrashort laser pulses characterization with amplitude swing.

In this work we firstly study the influence of different parameters in the temporal characterization of ultrashort laser pulses with the recently developed amplitude swing technique. In this technique, the relative amplitude of two delayed replicas is varied while measuring their second-harmonic spectra. Here we study the retrieval of noisy traces and the implications of having different delays or phase retardations (relative phases) between the two replicas.

Compact in-line temporal measurement of laser pulses with amplitude swing.

A method of ultrashort laser pulse reconstruction is presented, consisting on the analysis of the nonlinear signal obtained from the interference of the pulse with a replica of itself at a given time delay while varying the relative amplitude between the pulses. The resulting spectral traces are analyzed both analytically and numerically, showing the encoding of the input pulse spectral phase. A reconstruction algorithm is discussed and applied to extract the spectral phase and, jointly to the measured spectral amplitude, reconstructing the pulse.

All-optical measurement of the complete waveform of octave-spanning ultrashort light pulses.

We demonstrate the complete temporal characterization of the optical waveform of visible near-infrared octave-spanning ultrashort laser pulses, using an all-optical, all-solid-state, and fully inline dispersion-scan device based only on second-harmonic generation.

Theoretical analysis of single-cycle self-compression of near infrared pulses using high-spatial modes in capillary fibers: erratum.

The first equation in [Opt. Express26, 6345 (2018)] contains an error and is corrected in this erratum.

Tailoring the spatio-temporal distribution of diffractive focused ultrashort pulses through pulse shaping.

Focusing control of ultrashort pulsed beams is an important research topic, due to its impact to subsequent interaction with matter. In this work, we study the propagation near the focus of ultrashort laser pulses of ~25 fs duration under diffractive focusing. We perform the spatio-spectral and spatio-temporal measurements of their amplitude and phase, complemented by the corresponding simulations.

Theoretical analysis of single-cycle self-compression of near infrared pulses using high-spatial modes in capillary fibers.

Soliton self-compression is demonstrated during the propagation of high spatial modes in hollow core fibers in the near-infrared spectral region, taking advantage of their negative dispersion response. We have found that there is always an optimum spatial mode to observe this phenomenon, compressing the pulses down to the single-cycle regime without needing any external compression device and with a consequent increase in the output peak power. Our result is relevant for any ultrashort laser application in which few- or single-cycle pulses are crucial.

Self-calibrating d-scan: measuring ultrashort laser pulses on-target using an arbitrary pulse compressor.

In most applications of ultrashort pulse lasers, temporal compressors are used to achieve a desired pulse duration in a target or sample, and precise temporal characterization is important. The dispersion-scan (d-scan) pulse characterization technique usually involves using glass wedges to impart variable, well-defined amounts of dispersion to the pulses, while measuring the spectrum of a nonlinear signal produced by those pulses. This works very well for broadband few-cycle pulses, but longer, narrower bandwidth pulses are much more difficult to measure this way.

Strategies for achieving intense single-cycle pulses with in-line post-compression setups.

Intense few- and single-cycle pulses are powerful tools in different fields of science Today, third- and higher-order terms in the remnant spectral phase of the pulses remain a major obstacle for obtaining high-quality few- and single-cycle pulses from in-line post-compression setups. In this Letter, we show how input pulse shaping can successfully be applied to standard post-compression setups to minimize the occurrence of high-order phase components during nonlinear propagation and to directly obtain pulses with durations down to 3 fs. Furthermore, by combining this pulse shaping of the input pulse with new-generation broadband chirped mirrors and material addition for remnant third-order phase correction, pulses down to 2.

Holographic optical element to generate achromatic vortices.

A compound holographic optical element to generate achromatic vortices with high efficiency, based on the combination of two volume phase holograms, is designed and constructed. This element is compact and easy to align. It has high damage threshold, so it can be used with ultraintense laser pulses.

Spatiotemporal characterization of few-cycle laser pulses.

In this paper we apply a broadband fiber optic coupler interferometer to the measurement of few-cycle laser pulses. Sub-8-fs pulses delivered by an ultrafast oscillator were characterized spatiotemporally using STARFISH, which is based on spatially resolved spectral interferometry. The reference pulse was measured with the d-scan technique.

Synthesis of fractal light pulses by quasi-direct space-to-time pulse shaping.

We demonstrated a simple diffractive method to map the self-similar structure shown in squared radial coordinate of any set of circularly symmetric fractal plates into self-similar light pulses in the corresponding temporal domain. The space-to-time mapping of the plates was carried out by means of a kinoform diffractive lens under femtosecond illumination. The spatio-temporal characteristics of the fractal pulses obtained in this way were measured by means of a spectral interferometry technique assisted by a fiber optics coupler (STARFISH).

Multibeam second-harmonic generation by spatiotemporal shaping of femtosecond pulses.

We present a technique for efficient generation of the second-harmonic signal at several points of a nonlinear crystal simultaneously. Multispot operation is performed by using a diffractive optical element that splits the near-infrared light of a mode-locked Ti:sapphire laser into an arbitrary array of beams that are transformed into an array of foci at the nonlinear crystal. We show that, for pulse temporal durations under 100 fs, spatiotemporal shaping of the pulse is mandatory to overcome chromatic dispersion effects that spread both in space and time the foci showing a reduced peak intensity that prevents nonlinear phenomena.

Enhancement of filamentation postcompression by astigmatic focusing.

The energy scaling up of pulse postcompression is still an open issue. In this work we analyze the use of astigmatic focusing to improve the output pulses in a filamentation based postcompression setup. Unlike spherical conditions, astigmatic focusing enhances the output energy and the spectral broadening of the filament.

Spatio-temporal characterization of ultrashort pulses diffracted by circularly symmetric hard-edge apertures: theory and experiment.

We carry out a complete spatio-temporal characterization of the electric field of an ultrashort laser pulse after passing through a diffractive optical element composed of several binary amplitude concentric rings. Analytical expressions for the total diffraction field in the time and spectral domain are provided, using the Rayleigh-Sommerfeld formulation of the diffraction. These expressions are experimentally validated.

Above-millijoule super-continuum generation using polarisation dependent filamentation in atoms and molecules.

We demonstrate for the first time that input polarisation control inducing one single filamentation is a very robust technique to accurately control the filamentation dynamics enhancing throughput energy of the supercontinuum generation up to 1.2 millijoule. Reaching the above-millijoule regime opens the way to post-compression of multi-terawatt laser pulses.