Potential of Sub-THz-Wave Generation in Li2B4O7 Nonlinear Crystal at Room and Cryogenic Temperatures

Due to their high optical damage threshold, borate crystals can be used for the efficient nonlinear down-conversion of terawatt laser radiation into the terahertz (THz) frequency range of the electromagnetic spectrum. In this work, we carried out a thorough study of the terahertz optical properties of the lithium tetraborate crystal (Li2B4O7; LB4) at 295 and 77 K. Approximating the terahertz refractive index in the form of Sellmeier’s equations, we assessed the possibility of converting the radiation of widespread high-power laser sources with wavelengths of 1064 and 800 nm, as well as their second and third harmonics, into the THz range. It was found that four out of eight types of three-wave mixing processes are possible. The conditions for collinear phase matching were fulfilled only for the o − e → o type of interaction, while cooling the crystal to 77 K did not practically affect the phase-matching curves. However, a noticeable increase of birefringence in the THz range with cooling (from 0.12 to 0.16) led to an increase in the coherence length for o − o → e and e − e → e types of interaction, which are potentially attractive for the down-conversion of ultrashort laser pulses.

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Multiphoton absorption of ultrashort laser pulses in optical materials of multilayer coatings at near-damage-threshold fluence

Laser-induced Damage in Optical Materials 2020 ◽

10.1117/12.2572553 ◽

2020 ◽

Author(s):

Vitaly E. Gruzdev ◽

Kyle Kafka

Keyword(s):

Optical Materials ◽

Damage Threshold ◽

Laser Pulses ◽

Ultrashort Laser Pulses ◽

Multiphoton Absorption ◽

Multilayer Coatings ◽

Threshold Fluence ◽

Ultrashort Laser

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Application of Quasi-Phase Matching Concept for Enhancement of High-Order Harmonics of Ultrashort Laser Pulses in Plasmas

Applied Sciences ◽

10.3390/app9081701 ◽

2019 ◽

Vol 9 (8) ◽

pp. 1701 ◽

Cited By ~ 3

Author(s):

R. A. Ganeev ◽

S. Y. Stremoukhov ◽

A. V. Andreev ◽

A. S. Alnaser

Keyword(s):

Extreme Ultraviolet ◽

Laser Pulses ◽

Plasma Jets ◽

High Order ◽

Ultrashort Laser Pulses ◽

Phase Matching ◽

Quasi Phase Matching ◽

Fundamental Radiation ◽

Formation Conditions ◽

The One

Novel methods of coherent short-wavelength sources generation require thorough analysis for their further amendments and practical implementations. In this work, we report on the quasi-phase matching (QPM) of high-order harmonics generation during the propagation of single- and two-color femtosecond pulses through multi-jet plasmas, which allows the enhancement of groups of harmonics in different ranges of extreme ultraviolet. The role of the number of coherent zones; sizes of plasma jets and the distance between them; plasma formation conditions, and the characteristics of the fundamental radiation on the harmonic efficiency at quasi-phase matching (QPM) conditions are analyzed. We demonstrate the ~40× enhancement factor of the maximally-enhanced harmonic with respect to the one generated at ordinary conditions in the imperforated plasma.

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Ablation of BaWO4 Crystal by Ultrashort Laser Pulses

Crystals ◽

10.3390/cryst10090754 ◽

2020 ◽

Vol 10 (9) ◽

pp. 754

Author(s):

Igor Kinyaevskiy ◽

Pavel Danilov ◽

Nikita Smirnov ◽

Sergey Kudryashov ◽

Andrey Koribut ◽

...

Keyword(s):

Crystal Surface ◽

Damage Threshold ◽

Single Pulse ◽

Laser Pulses ◽

Ultrashort Laser Pulses ◽

Pulse Irradiation ◽

Optical Damage ◽

Order Of Magnitude ◽

Ultrashort Laser ◽

Optical Damage Threshold

Ablation of BaWO4 Raman crystals with different impurity concentrations by ultrashort laser pulses was experimentally studied. Laser pulses with duration varying from 0.3 ps to 1.6 ps at wavelengths of 515 nm and 1030 nm were applied. A single-pulse optical damage threshold of the crystal surface changed from 1.3 J/cm2 to 4.2 J/cm2 depending on the laser pulse parameters and BaWO4 crystal purity. The optical damage threshold under multi-pulse irradiation was an order of magnitude less.

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Phase matching in RT KTP crystal for down-conversion into the THz range

Laser Physics Letters ◽

10.1088/1612-202x/aabb30 ◽

2018 ◽

Vol 15 (7) ◽

pp. 075401 ◽

Cited By ~ 5

Author(s):

J-G Huang ◽

Z-M Huang ◽

N A Nikolaev ◽

A A Mamrashev ◽

V D Antsygin ◽

...

Keyword(s):

Phase Matching ◽

Ktp Crystal ◽

Thz Range ◽

Down Conversion

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Efficient Generation of Spectrum-Manipulated Few-Cycle Laser Pulses through Cascaded Dual-Chirped OPA

International Journal of Molecular Sciences ◽

10.3390/ijms22136887 ◽

2021 ◽

Vol 22 (13) ◽

pp. 6887

Author(s):

Zuofei Hong ◽

Han Zhang ◽

Shaolin Ke

Keyword(s):

Conversion Efficiency ◽

Strong Field ◽

Nonlinear Crystal ◽

Ultrafast Optics ◽

Laser Pulses ◽

Signal Spectrum ◽

Phase Matching ◽

Signal Pulse ◽

Efficient Generation ◽

Strong Field Physics

The cascaded dual-chirped optical parametric amplification (DC-OPA) is presented for efficient generation of few-cycle infrared (IR) laser pulses. The input pulses are strategically chirped to optimize the phase-matching bandwidth in each nonlinear crystal, and four regions of the signal spectrum are amplified in cascaded crystals with different cutting angles, enabling flexible manipulation of the output spectrum. Broadband gain and high conversion efficiency are simultaneously achieved owing to the cascaded-crystal arrangement, the signal pulse duration of 4.2 cycles is obtained with 11.7-mJ pulse energy, corresponding to a conversion efficiency of 39.0%. The proposed scheme offers a robust and simple approach to pushing the phase-matching bandwidth limits introduced by the nonlinear crystal, which manifests great prospect in various researches involving ultrafast optics and strong-field physics.

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Ultrafast laser heating of non-plasmonic nanocylinders

Journal of Physics Conference Series ◽

10.1088/1742-6596/2015/1/012104 ◽

2021 ◽

Vol 2015 (1) ◽

pp. 012104

Author(s):

Olesia Pashina ◽

Daniil Ryabov ◽

George Zograf ◽

Sergey Makarov ◽

Mihail Petrov

Keyword(s):

Damage Threshold ◽

Laser Pulses ◽

Dielectric Substrate ◽

Ultrashort Laser Pulses ◽

Experimental Conditions ◽

Pulsed Heating ◽

Heating Effects ◽

Ultrashort Laser ◽

Two Temperature ◽

Thermal Stability Of

Abstract We develop a model describing non-equilibrium processes under the excitation of resonant semiconductor nanostructures with ultrashort laser pulses with a duration of about 100 fs. We focus on the heating effects related to pulsed excitation with account on free carriers generation, thermalization, and relaxation. The heat exchange between the electron and phonon system is treated within the two-temperature model. We applied the developed model to describing pulsed heating of silicon nanocylinder on top of a dielectric substrate. We come up with estimations of the thermal damage threshold of the considered structures which provides the limits for the experimental conditions and ensures thermal stability of the samples.

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CALCULATION OF EFFECTIVE NONLINEAR COEFFICIENT IN BIBO FOR SPONTANEOUS PARAMETRIC DOWN CONVERSION

Journal of Nonlinear Optical Physics & Materials ◽

10.1142/s0218863513500100 ◽

2013 ◽

Vol 22 (01) ◽

pp. 1350010 ◽

Cited By ~ 3

Author(s):

GUANGWEN HUO ◽

TONGYI ZHANG ◽

GUANGHUA CHENG ◽

WEI ZHAO

Keyword(s):

Nonlinear Crystal ◽

Nonlinear Coefficient ◽

Phase Matching ◽

Double Phase ◽

Parametric Down Conversion ◽

Entangled Photon Pairs ◽

Effective Phase ◽

Matching Schemes ◽

Down Conversion ◽

Effective Nonlinear Coefficient

We theoretically investigate the effective nonlinear coefficient d eff of spontaneous parametric down-conversion (SPDC) process in biaxial nonlinear crystal BiB3O6 (BIBO). We solve the Fresnel equations in the collinear degenerate down-converted configuration, and get the relations of phase-matching angles. Considering the double phase-matching, we compute the phase-matching angles with different wavelength. Furthermore, we simplify the expression of effective nonlinear coefficient out of the principal planes, and numerically calculate it varying with the angle and wavelength. These results indicate that there are three effective phase-matching schemes for SPDC which can be used to construct a system to generate entangled photon pairs.

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Femtosecond Laser Assisted Crystallization of Gold Thin Films

Nanomaterials ◽

10.3390/nano11051186 ◽

2021 ◽

Vol 11 (5) ◽

pp. 1186

Author(s):

Ayesha Sharif ◽

Nazar Farid ◽

Rajani K. Vijayaraghavan ◽

Patrick J. McNally ◽

Gerard M. O’Connor

Keyword(s):

Thin Films ◽

Femtosecond Laser ◽

Quartz Substrate ◽

Damage Threshold ◽

Laser Pulses ◽

Industrial Applications ◽

Ultrashort Laser Pulses ◽

Gold Films ◽

Gold Thin Films ◽

Ultrashort Laser

We propose a novel low temperature annealing method for selective crystallization of gold thin films. Our method is based on a non-melt process using highly overlapped ultrashort laser pulses at a fluence below the damage threshold. Three different wavelengths of a femtosecond laser with the fundamental (1030 nm), second (515 nm) and third (343 nm) harmonic are used to crystallize 18-nm and 39-nm thick room temperature deposited gold thin films on a quartz substrate. Comparison of laser wavelengths confirms that improvements in electrical conductivity up to 40% are achievable for 18-nm gold film when treated with the 515-nm laser, and the 343-nm laser was found to be more effective in crystallizing 39-nm gold films with 29% improvement in the crystallinity. A two-temperature model provides an insight into ultrashort laser interactions with gold thin films and predicts that applied fluence was insufficient to cause melting of gold films. The simulation results suggest that non-equilibrium energy transfer between electrons and lattice leads to a solid-state and melt-free crystallization process. The proposed low fluence femtosecond laser processing method offers a possible solution for a melt-free thin film crystallization for wide industrial applications.

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