Harmonic Generation Research Articles

Generation of Massively Entangled Bright States of Light during Harmonic Generation in Resonant Media

At the fundamental level, full description of light-matter interaction requires quantum treatment of both matter and light. However, for standard light sources generating intense laser pulses carrying quadrillions of photons in a coherent state, the classical description of light during intense laser-matter interaction has been expected to be adequate. Here, we show how nonlinear optical response of matter can be controlled to generate dramatic deviations from this standard picture, including generation of several squeezed and entangled harmonics of the incident laser light. In particular, such nontrivial quantum states of harmonics are generated as soon as one of the harmonics induces a transition between different laser-dressed states of the material system. Such transitions generate an entangled light-matter wave function, which can generate quantum states of harmonics even in the absence of a quantum driving field or material correlations. In turn, entanglement of the material system with a single harmonic generates and controls entanglement between different harmonics. Hence, nonlinear media that are near resonant with at least one of the harmonics appear to be quite attractive for controlled generation of massively entangled quantum states of light. Our analysis opens remarkable opportunities at the interface of attosecond physics and quantum optics, with implications for quantum information science. Published by the American Physical Society 2025

Controlling Triplet-Harvesting Pathways and Nonlinear Optical Properties in Cu(I) Iodide-Based Polymers through Ligand Engineering.

Organic-inorganic hybrid metal halides have become enormously important in optoelectronics, sensing, photosensitization, etc. In this study, we report a structural transition from a staircase configuration to a cubane configuration in Cu(I) iodide-based polymers influenced by the coordination behavior of two different π*-acceptor ligands. The staircase polymer structure, coordinated with 3-cyanopyridine, demonstrates efficient thermally activated delayed fluorescence from (metal+halide)-to-ligand charge transfer [1/3(M+X)LCT] states, with a singlet-triplet energy splitting of ∼9 meV. Conversely, upon replacement of the cyano with an amino group at the same position, a one-dimensional polymeric structure of Cu4I4 cubane-type clusters is formed, which shows strong cluster-centered (3CC) orange emission at room temperature. Temperature-dependent photoluminescence studies indicate that the 3CC state behaves as a self-trapped excitonic state with significant exciton-phonon coupling having a Huang-Rhys factor of 58.6. Additionally, we report this cubane-type cluster polymer acts as an efficient nonlinear optical material showing third harmonic generation with a χ(3) value of 1.32 × 10-18 m2 V-2 and a laser-induced damage threshold of 25.87 GW/cm2.

New Ways to Discover Novel Nonlinear Optical Materials: Scaling Machine Learning with Chemical Descriptors Information.

The efficient experimental exploration of innovative nonlinear optical materials has long been a challenging task due to the vast chemical space and the lack of suitable theoretical prediction frameworks. Herein, a novel theoretical design paradigm is proposed to accelerate the discovery of novel materials with strong second harmonic generation intensity. This challenge is addressed through several key technologies. 1) A high-precision machine learning model is proposed on the maximum nonlinear optical dataset. 2) Descriptors information paves the way to systematically offer valuable chemical insights for designing chemical structures. 3) A flexible and fast chemical space constructionand exploration method is proposed. Accordingly, a nonlinear optical crystal is successfully synthesized through the constructed "machine to knowledge" theoretical framework. This novel compound exhibits a stronger second-harmonic generation response and wider optical transmission range. This work introduces novel theoretical design concepts and provides innovative chemical insights into optical materials or other functional materials.

Improving third harmonic generation performance by elevating the operation temperature of KDP and DKDP crystals

Improving third harmonic generation performance by elevating the operation temperature of KDP and DKDP crystals

Electric-field tuned second harmonic generation in twisted bilayer graphene

Electric-field tuned second harmonic generation in twisted bilayer graphene

Extendable Synthesis of Organic Cations for In Situ Construction of Hybrid Metal Halideswith Near-Unity Photoluminescenceand Strong Second Harmonic Generation.

The A-site organic components of organic-inorganic hybrid metal halides (OIHMHs) significantly impact their crystal structure and optoelectronic properties. However, chemical modification of A-site cations has been mostly limited to commercial organic precursors, which restricts thestructural variability of OIHMHs for optimal functionalities. Herein we have proposed an extendable synthesis approach to the direct procurability of various organic cations with desireable structures for the in situ construction of a library of OIHMH materials. The template condensation reaction between dimethyl sulfoxide and acetone derivatives yields A-site organic cations with exquisite control of modularization and regioselectivity within the OIHMH crystallization system. The as-fabricated OIHMHs demonstrated highly efficient linear optical photoluminescence or nonlinear optical second harmonic generation,promising potential applications in photonic devices. This in situ synthetic strategy offers a structural extension of OIHMHs and establishes afundamental methodological platform for screening functional OIHMH materials.

Extendable Synthesis of Organic Cations for In Situ Construction of Hybrid Metal Halides with Near‐Unity Photoluminescence and Strong Second Harmonic Generation

The A‐site organic components of organic‐inorganic hybrid metal halides (OIHMHs) significantly impact their crystal structure and optoelectronic properties. However, chemical modification of A‐site cations has been mostly limited to commercial organic precursors, which restricts the structural variability of OIHMHs for optimal functionalities. Herein we have proposed an extendable synthesis approach to the direct procurability of various organic cations with desireable structures for the in situ construction of a library of OIHMH materials. The template condensation reaction between dimethyl sulfoxide and acetone derivatives yields A‐site organic cations with exquisite control of modularization and regioselectivity within the OIHMH crystallization system. The as‐fabricated OIHMHs demonstrated highly efficient linear optical photoluminescence or nonlinear optical second harmonic generation, promising potential applications in photonic devices. This in situ synthetic strategy offers a structural extension of OIHMHs and establishes a fundamental methodological platform for screening functional OIHMH materials.

Attosecond electron dynamics in solid-state systems

Abstract Attosecond science has revolutionized the study of ultrafast electron dynamics. Originally based on high-order harmonic generation from intense laser fields, it provided groundbreaking insights into physical processes occurring on the few- to sub-femtosecond time scales. From its initial focus on atomic and molecular systems, the field rapidly expanded to solid-state materials, uncovering phenomena with possible significant implications for information technology. This review focuses on some of the key experimental techniques that enable attosecond resolution in solid-state systems. We categorize them into four main groups: core-hole clock spectroscopy, photoemission, XUV-based all-optical techniques, and sub-cycle strong-field approaches. Together, these methods contributed to significant breakthroughs, such as elucidating the timing of photoemission from solids, possibly enabling the manipulation of the electro-optical properties of a crystal with light fields, and advancing our understanding of fundamental light-matter interactions. Their application to novel materials and the development of innovative, cutting-edge light sources and techniques, will define the future of attoscience in solids, setting the basis for profound advancements in both scientific understanding and technological innovation.

Unveiling the impact of neighboring oxides: A detailed analysis of second and third harmonic generation in cylindrical ZnS/CdSe core/shell quantum dots

Unveiling the impact of neighboring oxides: A detailed analysis of second and third harmonic generation in cylindrical ZnS/CdSe core/shell quantum dots

Higher Harmonic Generation Arising from the Bessel Function Expansions of the Carrier-Envelope-Phase Driven by the Femtosecond Optical Kerr Effect

This paper expands upon previous reports based on the EM Kerr model-based HHG simulation from the carrier-envelope phase (CEP) of the electromagnetic laser light wave based on electronic self-phase modulation (ESPM) from the optical Kerr index. The underpinning mechanism described for generating HHG arises from the CEP of the nonlinear index of refraction, which yields a series of Bessel functions. The envelope of the electric field E(t) of the intense ultrashort light pulses drives the CEP, resulting in many Bessel functions, one of the salient features of HHG. The HHG from the large number of Bessel function modes can produce attosecond pulses and possibly can even produce zeptosecond pulses by Kerr mode-locking among the large number N of Bessel functions.

High harmonic generation in graphene quantum dots with vacancy defects

High harmonic generation in graphene quantum dots with vacancy defects

Maxwell-Wagner Effect and Second Optical Harmonic Generation in a Glass via Field-Assisted Ion Exchange

Maxwell-Wagner Effect and Second Optical Harmonic Generation in a Glass via Field-Assisted Ion Exchange

Impact of Paraben on Uterine Collagen: An Integrated and Targeted Correlative Approach Using Second Harmonic Generation Microscopy, Nanoindentation, and Atomic Force Microscopy

Impact of Paraben on Uterine Collagen: An Integrated and Targeted Correlative Approach Using Second Harmonic Generation Microscopy, Nanoindentation, and Atomic Force Microscopy

A theoretical prediction for generating isolated attosecond pulse in water window utilizing instantaneous frequency change of two-color driving laser pulse

This work reports on the theoretical generation of isolated soft-X ray 106 attosecond pulse within the water window spectral region, through interacting a chirped two-color femtosecond laser pulse with a hydrogen atom. To construct this pulse, a chirped 3.5 optical cycle (9.33 fs) laser pulse with a wavelength of 800 nm and an intensity of is used as the main field. A 37.32 fs laser pulse with a wavelength of 1600 nm and intensity of , one-quarter of the main field intensity, is employed as the control field. A tangential hyperbolic function is used to impose chirp on the main field. The study simultaneously utilizes the lowest possible intensity and the highest possible pulse duration for both the main and the control field to reach the water window spectral region in high-order harmonic generation up to the 320th harmonic of the driving field.

Temperature‐Responsive Photoluminescence of 1D Chiral Lead Halide Perovskites with Highly Anisotropic Second Harmonic Generation

Temperature‐Responsive Photoluminescence of <scp>1D</scp> Chiral Lead Halide Perovskites with Highly Anisotropic Second Harmonic Generation

Coherent harmonic generation of magnons in spin textures

Harmonic generation, a notable non-linear phenomenon, has promising applications in information processing. For spin-waves in ferromagnetic materials, great progress has been made in the generation higher harmonics, however probing the coherence of these higher harmonics is challenging. Here, using in-situ diamond sensors, we study the coherent harmonic generation of spin waves in a soft ferromagnet. High-order resonance lines are generated via a microwave input and detected by nitrogen-vacancy (NV) centers in nanodiamonds. The phase coherence of the harmonic spin waves is verified by the Rabi oscillations of the NV electron spins. Numerical simulations indicate that the harmonic generation by microwaves below the ferromagnetic resonance frequency is associated with the nonlinear mixing of spin waves by magnetization structures at the film edge. Our finding of geometry-induced magnon harmonic generation constitutes a new way to generate magnon combs with coherent high-order harmonics and may pave the way for magnon-based information processing and quantum sensing applications.

Efficient tunable nonlinearity in high Q-factor lithium niobate metasurface harnessing electric-field-induced second harmonic generation

Efficient tunable nonlinearity in high Q-factor lithium niobate metasurface harnessing electric-field-induced second harmonic generation

Monitoring Phase-matching of Third Harmonic Generation in Microbubble Whispering Gallery Mode Resonators by a Novel Dynamic Opto-thermal Disruption Method

Monitoring Phase-matching of Third Harmonic Generation in Microbubble Whispering Gallery Mode Resonators by a Novel Dynamic Opto-thermal Disruption Method

Third Harmonic Generation Of Cosh- Gaussian Laser Beam In Magnetized Plasma

Third Harmonic Generation Of Cosh- Gaussian Laser Beam In Magnetized Plasma

Green picosecond pulse over 10 µJ directly amplified by diode-pumped Pr3+:LiYF4 crystal

Green (522 nm) picosecond (1.87 ps) pulses of 17.8 µJ energy were obtained at the repetition rate of 10.086 kHz, with the beam quality of M2 x = 2.34 and M2y = 2.00, by regeneratively amplifying a chirped green seed pulse (6.77 ps) from the second harmonic generation of the mode-locked Yb3+-doped fiber laser in the Pr3+ doped LiYF4 gain crystal, pumped by GaN laser diodes. A compression of the duration of the amplified pulse from 1.87 ps to 1.34 ps was also demonstrated.