Ultrafast mid-infrared high harmonic and supercontinuum generation with n<sub>2</sub> characterization in zinc selenide

Werner, Kevin; Hastings, Michael G.; Schweinsberg, Aaron; Wilmer, Brian; Austin, Drake; Wolfe, Christopher; Kolesík, M.; Ensley, Trenton R.; Vanderhoef, Laura; Valenzuela, Anthony; Chowdhury, Enam

doi:10.1364/oe.27.002867

Cited by 58 publications

(27 citation statements)

References 36 publications

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“…It was reported by Alfano and Shapiro in 1970 [3]. Since then, it has been observed in a wide variety of bulk nonlinear media [4][5][6][7][8] and various types of waveguides [9][10][11]. Today, broadband SC generation has found numerous applications, such as high-precision spectroscopy [12][13][14], frequency metrology and synthesis [15][16][17], ultrashort-pulse generation [18], wavelengthdivision-multiplexing (WDM) communication [19], and nonlinear optical spectroscopy and imaging in biophotonics [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Supercontinuum Generation Assisted by Wave Trapping in Dispersion-Managed Integrated Silicon Waveguides

et al. 2020

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Compact chip-scale comb sources are of significant interest for many practical applications. Here, we experimentally study the generation of supercontinuum (SC) in an axially varying integrated waveguide. We show that the local tuning of the dispersion enables the continuous blue shift of dispersive waves by more than 200 nm due to their trapping by the strongly compressed pump pulse. This mechanism provides an insight into supercontinuum generation in varying-dispersion integrated waveguides. Pumped close to 2.2 μm in the femtosecond regime and at a pulse energy of approximately 4 pJ, the output spectrum extends from 1.1 μm up to 2.76 μm and shows good coherence properties. Octave-spanning SC is also observed at an input energy as low as approximately 0.9 pJ. We show that the supercontinuum is more robust against variations of the input-pulse parameters and is also spectrally flatter in waveguides with an optimized dispersion profile than in dispersion-engineered ones. This research demonstrates the potential of varying-dispersion waveguides for coherent SC generation and paves the way for integrated low-power applications, such as chip-scale frequency-comb generation, precision spectroscopy, optical-frequency metrology, and wide-band wavelength division multiplexing in the near infrared.

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Section: Introductionmentioning

confidence: 99%

Supercontinuum Generation Assisted by Wave Trapping in Dispersion-Managed Integrated Silicon Waveguides

et al. 2020

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“…A home-built Ti:Sapphire ultrashort pulse laser [ 31 ] is converted to MIR wavelengths via the Extreme Mid-InfraRed (EMIR) optical parametric amplifier (OPA) [ 3 , 32 ] with central wavelength

µm, pulsed repetition frequency (PRF) of 500 Hz, and pulse duration of

fs full-width at half-maximum (FWHM).…”

Section: Materials and Methodsmentioning

confidence: 99%

Extreme Sub-Wavelength Structure Formation from Mid-IR Femtosecond Laser Interaction with Silicon

Werner

Chowdhury

2021

Nanomaterials

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Mid-infrared (MIR) wavelengths (2–10 μμm) open up a new paradigm for femtosecond laser–solid interactions. On a fundamental level, compared to the ubiquitous near-IR (NIR) or visible (VIS) laser interactions, MIR photon energies render semiconductors to behave like high bandgap materials, while driving conduction band electrons harder due to the λ2 scaling of the ponderomotive energy. From an applications perspective, many VIS/NIR opaque materials are transparent for MIR. This allows sub-surface modifications for waveguide writing while simultaneously extending interactions to higher order processes. Here, we present the formation of an extreme sub-wavelength structure formation (∼λ/100) on a single crystal silicon surface by a 3600 nm MIR femtosecond laser with a pulse duration of 200 fs. The 50–100 nm linear structures were aligned parallel to the laser polarization direction with a quasi-periodicity of 700 nm. The dependence of the structure on the native oxide, laser pulse number, and polarization were studied. The properties of the structures were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), cross-sectional transmission electron-microscopy (CS-TEM), electron diffraction (ED), and energy-dispersive X-ray spectroscopy (EDX). As traditional models for the formation of laser induced periodic surface structure do not explain this structure formation, new theoretical efforts are needed.

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“…where d 2 = 15 pm/V is the effective second-order nonlinear susceptibility, r(z) is a random function between 0 and 1 representing propagation through different grains of the polycrystalline ZnSe. In our simulations, we switch on the random function r(z) at every 70 µm step so that it is a constant for 70 µm propagation and is a different constant for the next 70 µm propagation, mimicking the grain size of a polycrystal [36] . The calculated on-axis and spatially averaged spectra from ZnSe with the input energy of 10 µJ as functions of propagation distance are shown in Figures 7(a) and 7(b), respectively.…”

Section: Numerical Approachmentioning

confidence: 99%

Multi-octave-spanning supercontinuum generation through high-energy laser filaments in YAG and ZnSe pumped by a 2.4 μm femtosecond Cr:ZnSe laser

Nam

Nagar

Dempsey

et al. 2021

High Pow Laser Sci Eng

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We present experimental and numerical investigations of high-energy mid-infrared filamentation with multi-octave-spanning supercontinuum generation (SCG), pumped by a 2.4 μm, 250 fs Cr:ZnSe chirped-pulse laser amplifier. The SCG is demonstrated in both anomalous and normal dispersion regimes with YAG and polycrystalline ZnSe, respectively. The formation of stable and robust single filaments along with the visible-to-mid-infrared SCG is obtained with a pump energy of up to 100 μJ in a 6-mm-long YAG medium. To the best of the authors’ knowledge, this is the highest-energy multi-octave-spanning SCG from a laser filament in a solid. On the other hand, the SCG and even-harmonic generation based on random quasi-phase matching (RQPM) are simultaneously observed from the single filaments in a 6-mm-long polycrystalline ZnSe medium with a pump energy of up to 15 μJ. The numerical simulations based on unidirectional pulse propagation equation and RQPM show excellent agreement with the measured multi-octave-spanning SCG and even-harmonic generation. They also reveal the temporal structure of mid-infrared filaments, such as soliton-like self-compression in YAG and pulse broadening in ZnSe.

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Ultrafast mid-infrared high harmonic and supercontinuum generation with n₂ characterization in zinc selenide

Abstract: mid-infrared high harmonic and supercontinuum generation with n2 characterization in zinc selenide," Opt.

Cited by 58 publications

References 36 publications

Supercontinuum Generation Assisted by Wave Trapping in Dispersion-Managed Integrated Silicon Waveguides

Supercontinuum Generation Assisted by Wave Trapping in Dispersion-Managed Integrated Silicon Waveguides

Extreme Sub-Wavelength Structure Formation from Mid-IR Femtosecond Laser Interaction with Silicon

Multi-octave-spanning supercontinuum generation through high-energy laser filaments in YAG and ZnSe pumped by a 2.4 μm femtosecond Cr:ZnSe laser

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Ultrafast mid-infrared high harmonic and supercontinuum generation with n2 characterization in zinc selenide

Abstract: mid-infrared high harmonic and supercontinuum generation with n2 characterization in zinc selenide," Opt.

Cited by 58 publications

References 36 publications

Supercontinuum Generation Assisted by Wave Trapping in Dispersion-Managed Integrated Silicon Waveguides

Supercontinuum Generation Assisted by Wave Trapping in Dispersion-Managed Integrated Silicon Waveguides

Extreme Sub-Wavelength Structure Formation from Mid-IR Femtosecond Laser Interaction with Silicon

Multi-octave-spanning supercontinuum generation through high-energy laser filaments in YAG and ZnSe pumped by a 2.4 μm femtosecond Cr:ZnSe laser

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Ultrafast mid-infrared high harmonic and supercontinuum generation with n₂ characterization in zinc selenide