scholarly journals Subwavelength dielectric resonators for nonlinear nanophotonics

Science ◽  
2020 ◽  
Vol 367 (6475) ◽  
pp. 288-292 ◽  
Author(s):  
Kirill Koshelev ◽  
Sergey Kruk ◽  
Elizaveta Melik-Gaykazyan ◽  
Jae-Hyuck Choi ◽  
Andrey Bogdanov ◽  
...  
Keyword(s):  
Bound States ◽  
Second Harmonic ◽  
Nonlinear Effects ◽  
Dielectric Materials ◽  
High Index ◽  
Dielectric Resonators ◽  
Quality Factors ◽  
Second Harmonic Generation Efficiency ◽  
Radiative Losses ◽  
Nanoscale Lasers

Subwavelength optical resonators made of high-index dielectric materials provide efficient ways to manipulate light at the nanoscale through mode interferences and enhancement of both electric and magnetic fields. Such Mie-resonant dielectric structures have low absorption, and their functionalities are limited predominantly by radiative losses. We implement a new physical mechanism for suppressing radiative losses of individual nanoscale resonators to engineer special modes with high quality factors: optical bound states in the continuum (BICs). We demonstrate that an individual subwavelength dielectric resonator hosting a BIC mode can boost nonlinear effects increasing second-harmonic generation efficiency. Our work suggests a route to use subwavelength high-index dielectric resonators for a strong enhancement of light–matter interactions with applications to nonlinear optics, nanoscale lasers, quantum photonics, and sensors.

scholarly journals Significantly enhanced second-harmonic generations with all-dielectric antenna array working in the quasi-bound states in the continuum and excited by linearly polarized plane waves

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Zhanghua Han ◽  
Fei Ding ◽  
Yangjian Cai ◽  
Uriel Levy
Keyword(s):  
Second Harmonic Generation ◽  
Magnetic Dipole ◽  
Harmonic Generation ◽  
Bound States ◽  
Second Harmonic ◽  
Generation Efficiency ◽  
Second Harmonic Generation Efficiency ◽  
Linearly Polarized ◽  
Magnetic Dipole Resonances ◽  
The Continuum

AbstractThe recently emerging all-dielectric optical nanoantennas based on high-index semiconductors have proven to be an effective and low-loss alternative to metal-based plasmonic structures for light control and manipulations of light–matter interactions. Nonlinear optical effects have been widely investigated to employ the enhanced interactions between incident light and the dielectrics at the Mie-type resonances, and in particular magnetic dipole resonances, which are supported by the semiconductor. In this paper, we explore the novel phenomenon of bound states in the continuum supported by high-index semiconductor nanostructures. By carefully designing an array of nanodisk structures with an inner air slot as the defect, we show that a novel high quality-factor resonance achieved based on the concept of bound state in the continuum can be easily excited by the simplest linearly polarized plane wave at normal incidence. This resonance further enhances the interactions between light and semiconductors and boosts the nonlinear effects. Using AlGaAs as the nonlinear material, we demonstrate a significant increase in the second-harmonic generation efficiency, up to six orders of magnitude higher than that achieved by magnetic dipole resonances. In particular, a second-harmonic generation efficiency around 10% can be numerically achieved at a moderate incident pump intensity of 5 MW/cm2.

scholarly journals Engineering gallium phosphide nanostructures for efficient nonlinear photonics and enhanced spectroscopies

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gianni Q. Moretti ◽  
Emiliano Cortés ◽  
Stefan A. Maier ◽  
Andrea V. Bragas ◽  
Gustavo Grinblat
Keyword(s):  
Magnetic Dipole ◽  
Bound States ◽  
Gallium Phosphide ◽  
Second Harmonic ◽  
Periodic Array ◽  
Experimental Investigations ◽  
Point Dipole ◽  
Quality Factors ◽  
Cell Conversion ◽  
Elliptical Cylinders

Abstract Optical resonances arising from quasi-bound states in the continuum (QBICs) have been recently identified in nanostructured dielectrics, showing ultrahigh quality factors accompanied by very large electromagnetic field enhancements. In this work, we design a periodic array of gallium phosphide (GaP) elliptical cylinders supporting, concurrently, three spectrally separated QBIC resonances with in-plane magnetic dipole, out-of-plane magnetic dipole, and electric quadrupole characters. We numerically explore this system for second-harmonic generation and degenerate four-wave mixing, demonstrating giant per unit cell conversion efficiencies of up to ∼ 2 W−1 and ∼ 60 W−2, respectively, when considering realistic introduced asymmetries in the metasurface, compatible with current fabrication limitations. We find that this configuration outperforms by up to more than four orders of magnitude the response of low-Q Mie or anapole resonances in individual GaP nanoantennas with engineered nonlinear mode-matching conditions. Benefiting from the straight-oriented electric field of one of the examined high-Q resonances, we further propose a novel nanocavity design for enhanced spectroscopies by slotting the meta-atoms of the periodic array. We discover that the optical cavity sustains high-intensity fields homogeneously distributed inside the slot, delivering its best performance when the elliptical cylinders are cut from end to end forming a gap, which represents a convenient model for experimental investigations. When placing an electric point dipole inside the added aperture, we find that the metasurface offers ultrahigh radiative enhancements, exceeding the previously reported slotted dielectric nanodisk at the anapole excitation by more than two orders of magnitude.

scholarly journals Doubly-Resonant Photonic Crystal Cavities for Efficient Second-Harmonic Generation in III–V Semiconductors

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 605
Author(s):  
Simone Zanotti ◽  
Momchil Minkov ◽  
Shanhui Fan ◽  
Lucio C. Andreani ◽  
Dario Gerace
Keyword(s):  
Photonic Crystal ◽  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Nonlinear Effects ◽  
Photonic Materials ◽  
Second Harmonic Generation Efficiency ◽  
Semiconductor Compounds ◽  
Localized Defects ◽  
Small Footprint

Second-order nonlinear effects, such as second-harmonic generation, can be strongly enhanced in nanofabricated photonic materials when both fundamental and harmonic frequencies are spatially and temporally confined. Practically designing low-volume and doubly-resonant nanoresonators in conventional semiconductor compounds is challenging owing to their intrinsic refractive index dispersion. In this work we review a recently developed strategy to design doubly-resonant nanocavities with low mode volume and large quality factor via localized defects in a photonic crystal structure. We built on this approach by applying an evolutionary optimization algorithm in connection with Maxwell equations solvers; the proposed design recipe can be applied to any material platform. We explicitly calculated the second-harmonic generation efficiency for doubly-resonant photonic crystal cavity designs in typical III–V semiconductor materials, such as GaN and AlGaAs, while targeting a fundamental harmonic at telecom wavelengths and fully accounting for the tensor nature of the respective nonlinear susceptibilities. These results may stimulate the realization of small footprint photonic nanostructures in leading semiconductor material platforms to achieve unprecedented nonlinear efficiencies.

scholarly journals Multipolar second-harmonic generation from high-Q quasi-BIC states in subwavelength resonators

Nanophotonics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 3953-3963 ◽  
Author(s):  
Irina Volkovskaya ◽  
Lei Xu ◽  
Lujun Huang ◽  
Alexander I. Smirnov ◽  
Andrey E. Miroshnichenko ◽  
...  
Keyword(s):  
Bound States ◽  
Second Harmonic ◽  
Quality Factors ◽  
Coupled Mode ◽  
Harmonic Radiation ◽  
Full Wave ◽  
Resonant States ◽  
Azimuthally Polarized Beam ◽  
Second Harmonic Radiation ◽  
Pump Depletion

AbstractWe put forward the multipolar model which captures the physics behind linear and nonlinear response driven by high-quality (high-Q) supercavity modes in subwavelength particles. We show that the formation of such trapped states associated with bound states in the continuum (quasi-BIC) can be understood through multipolar transformations of coupled leaky modes. The quasi-BIC state appears with increasing the order of the dominating multipole, where dipolar losses are completely suppressed. The efficient optical coupling to this state in the AlGaAs nanodisk is implemented via azimuthally polarized beam illumination matching its multipolar origin. We establish a one-to-one correspondence between the standard phenomenological non-Hermitian coupled-mode theory and multipolar models. The derived multipolar composition of the generated second-harmonic radiation from the AlGaAs nanodisk is then validated with full-wave numerical simulations. Back-action of the second-harmonic radiation onto the fundamental frequency is taken into account in the coupled nonlinear model with pump depletion. A hybrid metal-dielectric nanoantenna is proposed to augment the conversion efficiency up to tens of per cent due to increasing quality factors of the involved resonant states. Our findings delineate novel promising strategies in the design of functional elements for nonlinear nanophotonics applications.

scholarly journals Raman scattering in high-refractive-index nanostructures

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Søren Raza ◽  
Anders Kristensen
Keyword(s):  
Raman Spectroscopy ◽  
Refractive Index ◽  
Raman Scattering ◽  
Bound States ◽  
Stimulated Raman Scattering ◽  
Dielectric Materials ◽  
High Refractive Index ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Enhancement ◽  
The Impact

AbstractThe advent of resonant dielectric nanomaterials has provided a new path for concentrating and manipulating light on the nanoscale. Such high-refractive-index materials support a diverse set of low-loss optical resonances, including Mie resonances, anapole states, and bound states in the continuum. Through these resonances, high-refractive-index materials can be used to engineer the optical near field, both inside and outside the nanostructures, which opens up new opportunities for Raman spectroscopy. In this review, we discuss the impact of high-refractive-index nano-optics on Raman spectroscopy. In particular, we consider the intrinsic Raman enhancement produced by different dielectric resonances and their theoretical description. Using the optical reciprocity theorem, we derive an expression which links the Raman enhancement to the enhancement of the stored electric energy. We also address recent results on surface-enhanced Raman spectroscopy based on high-refractive-index dielectric materials along with applications in stimulated Raman scattering and nanothermometry. Finally, we discuss the potential of Raman spectroscopy as a tool for detecting the optical near-fields produced by dielectric resonances, complementing reflection and transmission measurements.

scholarly journals L-alaninium perrhenate: crystal structure and non-linear optical properties

2014 ◽  
Vol 12 (10) ◽  
pp. 1016-1022 ◽  
Author(s):  
Vitor Rodrigues ◽  
Maria Costa ◽  
Etelvina Gomes ◽  
Dmitry Isakov ◽  
Michael Belsley
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Second Harmonic ◽  
Negative Ions ◽  
Damage Threshold ◽  
Linear Optics ◽  
Second Harmonic Generation Efficiency ◽  
Non Linear ◽  
Linear Optical Properties ◽  
Linear Optical

AbstractThe crystal structure and non-linear optical properties of L-alaninium perrhenate, C3H8NO2+ ReO4 −, are reported. The protonated amino acid and the perrhenate anion have their usual geometries. The three-dimensional hydrogen-bonded network can be seen as a stacking of layers parallel to the (100) planes. Each layer is formed by chains of alternating positive and negative ions along the b and c axes. Hydrogen bonding of adjacent layers forms alternating chains along the a axis. A high damage threshold and a second-harmonic generation efficiency three times that of KDP make this new material potentially useful in non-linear optics.

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