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To date, second-harmonic generation (SHG) at nanoscale has been concentrated on employing high-refractive-index nanostructures, owing to the strong field confinement at deep subwavelength scales based on optically resonant effects. However,…

Second harmonic generation (SHG), as one of the most significant \c{hi}(2) nonlinear optical processes, plays crucial roles in a broad variety of optical and photonic applications. Designing various delicate schemes to achieve highly…

Optics · Physics 2021-09-01 Lei Wang , XiuQuan Zhang , Feng Chen

We experimentally study the behavior of orbital angular momentum (OAM) of light in a noncollinear second harmonic generation (SHG) process. The experiment is performed by using a type I BBO crystal under phase matching conditions with…

We report the observation of optical second harmonic generation (SHG) in single-layer indium selenide (InSe). We measure a second harmonic signal of $>10^3$ $\textrm{cts/s}$ under nonresonant excitation using a home-built confocal…

Second-order nonlinearity gives rise to many distinctive physical phenomena, e.g., second-harmonic generation, which plays an important role in fundamental science and various applications. Lithium niobate, one of the most widely used…

While liquid crystals (LCs) have been extensively studied, obtaining a comprehensive nanoscale picture of their molecular organization remains challenging, as conventional techniques face an intrinsic trade-off between spatial and chemical…

We derive the $\mathcal{T}$-matrix formalism tailored for numerical analysis of second-harmonic (SH) generation from arbitrarily shaped particles made of centrosymmetric optical materials. First, the transfer matrix of a single particle is…

Optics · Physics 2025-08-18 Ivan Sekulic , Ji Tong Wang , Jian Wei You , Nicolae C. Panoiu

A general method is described for finding algebraic expressions for matrix elements of any one- and two-particle operator for an arbitrary number of subshells in an atomic configuration, requiring neither coefficients of fractional…

Atomic Physics · Physics 2009-11-10 G. Gaigalas , Z. Rudzikas , C. Froese Fischer

We analytically investigate the effect of a non-centrosymmetric geometry in the optical second harmonic (SH) generation from a particle made of a centrosymmetric material, in the interior of which quadratic optical processes are suppressed.…

Optics · Physics 2019-03-27 Raksha Singla , W. Luis Mochán

The theory of Bloembergen and Pershan for the light waves at the boundary of nonlinear media is extended to a nonlinear two-dimensional atomic crystal, i.e. a single planar atomic lattice, placed in between linear bulk media. The crystal is…

Optics · Physics 2016-01-20 Michele Merano

Nonlinear optical generation has been a well-established way to realize frequency conversion in nonlinear optics, whereas previous studies were just focusing on the scalar light fields. Here we report a concise yet efficient experiment to…

Optics · Physics 2018-11-20 Li Zhang , Fei Lin , Xiaodong Qiu , Lixiang Chen

The study of the non-linear response of matter to high electric fields has recently encompassed harmonic generation in solids at near-infrared (NIR) driving wavelengths. Interest has been driven by the prospect of ultrafast signal…

A comparative experimental investigation of the dependence of second harmonic generation (SHG) on applied external voltage between the standard nematic liquid crystalline material and an analogue ferromagnetic nematic liquid crystalline…

Soft Condensed Matter · Physics 2019-09-30 Jure Brence , Luka Cmok , Nerea Sebastian , Alenka Mertelj , Darja Lisjak , Irena Drevensek-Olenik

Second-order nonlinear optical materials enable frequency doubling of light (second-harmonic generation, SHG), which is essential for optoelectronic applications ranging from materials characterization to quantum technologies. However,…

Materials Science · Physics 2026-03-25 Aubrey G. J. Nyiri , Michael J. Waters , James M. Rondinelli

Due to their abundant use in all-solid-state lasers, nonlinear optical (NLO) crystals are needed for many applications across diverse fields such as medicine and communication. However, because of conflicting requirements, the design of…

Materials Science · Physics 2025-08-13 Victor Trinquet , Matthew L. Evans , Gian-Marco Rignanese

In this paper, the optimal solution of effective nonlinear coefficient of quasi-phase-matching (QPM) crystals for coupled third harmonic generation (CTHG) was numerically investigated. The effective nonlinear coefficient of CTHG was…

Optics · Physics 2024-03-08 Zihua Zheng , Ziwen Tang , Zhiyi Wei , Jinghua Sun

High-efficiency second-harmonic generation (SHG) in compact integrated photonic systems is crucial for advancing nonlinear optical technologies. However, achieving exceptional conversion efficiencies while maintaining stable performance…

We demonstrate the highest efficiency ($\sim$80%) second harmonic generation (SHG) of Joule level, 27 femtosecond, high contrast pulses in a type-I lithium triborate (LBO) crystal. In comparison, potassium dihydrogen phosphate (KDP) gives a…

Material systems with lone-pair electrons have long been a treasure trove in the search for large second harmonic generation effects. Revealing the origin of second harmonic generation in nonlinear optical materials can provide theoretical…

Materials Science · Physics 2025-05-13 Fuming Li , Shilie Pan , Zhihua Yang

Understanding the mechanisms and spatial correlations of crystallographic symmetry breaking in ferroelectric materials is essential to tuning their functional properties. While optical second harmonic generation (SHG) has long been utilized…

Materials Science · Physics 2022-08-10 Wei Li , Yunpeng Ma , Tianyi Feng , Sergei V. Kalinin , Jing-Feng Li , Qian Li