Measurement of 10 fs pulses across the entire Visible to Near-Infrared Spectral Range

Johnson, Allan S.; Amuah, Emmanuel B.; Brahms, Christian; Wall, Simon

doi:10.1038/s41598-020-61620-z

Cited by 19 publications

(15 citation statements)

References 43 publications

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“…It also brings in the ease and flexible range of the needed measurements. For example, if the SH wavelength becomes too large for available spectrometers, we can instead record the TH, and the same is true of the reversed situation 49 .…”

Section: Discussionmentioning

confidence: 99%

Near-zero-index ultra-fast pulse characterization

et al. 2022

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Transparent conducting oxides exhibit giant optical nonlinearities in the near-infrared window where their linear index approaches zero. Despite the magnitude and speed of these nonlinearities, a “killer” optical application for these compounds has yet to be found. Because of the absorptive nature of the typically used intraband transitions, out-of-plane configurations with short optical paths should be considered. In this direction, we propose an alternative frequency-resolved optical gating scheme for the characterization of ultra-fast optical pulses that exploits near-zero-index aluminium zinc oxide thin films. Besides the technological advantages in terms of manufacturability and cost, our system outperforms commercial modules in key metrics, such as operational bandwidth, sensitivity, and robustness. The performance enhancement comes with the additional benefit of simultaneous self-phase-matched second and third harmonic generation. Because of the fundamental importance of novel methodologies to characterise ultra-fast events, our solution could be of fundamental use for numerous research labs and industries.

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Section: Discussionmentioning

confidence: 99%

Near-zero-index ultra-fast pulse characterization

et al. 2022

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“…S2 ). Further details of these sources can be found in Johnson et al 45 and Amuah et al 46 An achromatic ultrafast spectroscopy system compatible with few-cycle duration pulses was used to perform the pump-probe measurements at near-normal incidence. The LSMO sample was held in a closed cycle helium cryostat at 180 K, and pump-induced changes to the probe reflectivity were recorded with a pair of diodes sampling the parallel and perpendicular polarization components.…”

Section: Methodsmentioning

confidence: 99%

“…Supplementary Figure S2: Pump and probe pulse durations. a Pump and probe pulses used in the reflection anisotropy setup reconstructed using frequency-resolved optical gating 32 . The 800 nm pulses are of 50 fs duration (full-width half maximum) and the 1500 nm probe pulses are 60 fs duration.…”

Section: Author Contributionsmentioning

confidence: 99%

Multi-mode excitation drives disorder during the ultrafast melting of a C4-symmetry-broken phase

et al. 2022

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Spontaneous C4-symmetry breaking phases are ubiquitous in layered quantum materials, and often compete with other phases such as superconductivity. Preferential suppression of the symmetry broken phases by light has been used to explain non-equilibrium light induced superconductivity, metallicity, and the creation of metastable states. Key to understanding how these phases emerge is understanding how C4 symmetry is restored. A leading approach is based on time-dependent Ginzburg-Landau theory, which explains the coherence response seen in many systems. However, we show that, for the case of the single layered manganite La0.5Sr1.5MnO4, the theory fails. Instead, we find an ultrafast inhomogeneous disordering transition in which the mean-field order parameter no longer reflects the atomic-scale state of the system. Our results suggest that disorder may be common to light-induced phase transitions, and methods beyond the mean-field are necessary for understanding and manipulating photoinduced phases.

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“…FROG has been implemented using different optical setups and nonlinear processes including collinear setups, where the laser beam paths overlap, for secondharmonic generation (SHG), 3 third-harmonic generation (THG), 4 and noncollinear setups. 5 In an autocorrelation FROG measurement, two copies of the same pulse are combined inside a nonlinear medium. Alternatively, in a crosscorrelation FROG measurement, a known reference pulse is combined with an unknown pulse to generate nondegenerate signals such as sum-frequency generation (SFG) or four-wave mixing (FWM).…”

Section: ■ Introductionmentioning

confidence: 99%

Simultaneous Characterization of Two Ultrashort Optical Pulses at Different Frequencies Using a WS₂ Monolayer

2022

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The precise characterization of ultrashort laser pulses has been of interest to the scientific community for many years. Frequency-resolved optical gating (FROG) has been extensively used to retrieve the temporal and spectral field distributions of ultrashort laser pulses. In this work, we exploit the high, broad-band nonlinear optical response of a WS 2 monolayer to simultaneously characterize two ultrashort laser pulses with different frequencies. The relaxed phase-matching conditions in a WS 2 monolayer enable the simultaneous acquisition of the spectra resulting from both four-wave mixing (FWM) and sum-frequency generation (SFG) nonlinear processes while varying the time delay between the two ultrashort pulses. Next, we introduce an adjusted double-blind FROG algorithm, based on iterative fast Fourier transforms between two FROG traces, to extract the intensity distribution and phase of two ultrashort pulses from the combination of their FWM and SFG FROG traces. Using this algorithm, we find an agreement between the computed and observed FROG traces for both the FWM and SFG processes. Exploiting the broad-band nonlinear response of a WS 2 monolayer, we additionally characterize one of the pulses using a second-harmonic generation (SHG) FROG trace to validate the pulse shapes extracted from the combination of the FWM and SFG FROG traces. The retrieved pulse shape from the SHG FROG agrees well with the pulse shape retrieved from our nondegenerate cross-correlation FROG measurement. In addition to the nonlinear parametric processes, we also observe a nonlinearly generated photoluminescence (PL) signal emitted from the WS 2 monolayer. Because of its nonlinear origin, the PL signal can also be used to obtain complementary autocorrelation and cross-correlation traces.

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Measurement of 10 fs pulses across the entire Visible to Near-Infrared Spectral Range

Cited by 19 publications

References 43 publications

Near-zero-index ultra-fast pulse characterization

Near-zero-index ultra-fast pulse characterization

Multi-mode excitation drives disorder during the ultrafast melting of a C4-symmetry-broken phase

Simultaneous Characterization of Two Ultrashort Optical Pulses at Different Frequencies Using a WS₂ Monolayer

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Measurement of 10 fs pulses across the entire Visible to Near-Infrared Spectral Range

Cited by 19 publications

References 43 publications

Near-zero-index ultra-fast pulse characterization

Near-zero-index ultra-fast pulse characterization

Multi-mode excitation drives disorder during the ultrafast melting of a C4-symmetry-broken phase

Simultaneous Characterization of Two Ultrashort Optical Pulses at Different Frequencies Using a WS2 Monolayer

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Simultaneous Characterization of Two Ultrashort Optical Pulses at Different Frequencies Using a WS₂ Monolayer