Tunable Second-Harmonic Studies of Gan Films Near the Fundamental Bandedge

1994 ◽  
Vol 339 ◽  
Author(s):  
Joseph Miragliotta ◽  
Wayne A. Bryden ◽  
Thomas J. Kistenmacher ◽  
Dennis K. Wickenden
Keyword(s):  
Photon Energy ◽  
Absorption Edge ◽  
Nonlinear Response ◽  
Second Harmonic ◽  
Wide Bandgap ◽  
Second Order ◽  
Nonlinear Susceptibility ◽  
Transmission Measurements

ABSTRACTTunable second-harmonic (SH) transmission measurements were performed on a series of GaN films epitaxially deposited onto (OOOl)-oriented sapphire. Analysis of the nonlinear response showed an increase in the second-order nonlinear susceptibility (χ(2)ijk) when the photon energy of the SH field was tuned above the absorption edge in each respective film. Specifically, the magnitude of the χ(2)zxx element in χ(2)ijk reached a maximum of 0.5 × 10-7 e.s.u. just above the the fundamental bandgap with a dispersion similar to the predicted nonlinear response in wide-bandgap cubic zincblende II-VI semiconductors such as ZnSe.

scholarly journals A Molecular Architectural Approach to Second-Order Nonlinear Optical Materials

1995 ◽  
Vol 392 ◽  
Author(s):  
Xiaoguang Yang ◽  
Duncan McBranch ◽  
Basil Swanson ◽  
Dequan Li
Keyword(s):  
Nonlinear Optical ◽  
Second Harmonic ◽  
Fused Silica ◽  
Second Order ◽  
Nonlinear Susceptibility ◽  
Design And Synthesis ◽  
Fundamental Wavelength ◽  
Assembled Monolayers ◽  
Methylene Groups ◽  
Nlo Chromophores

AbstractThe design and synthesis of a family of calix[4]arene-based nonlinear optical (NLO) chromophores are discussed. The calixarene chromophores are macrocyclic compounds consisting of four simple D-π-A units bridged by methylene groups. These molecules were synthesized such that four D-π-A units of the calix[4]arene were aligned along the same direction with the calixarene in a cone conformation. These nonlinear optical super-chromophores were subsequently fabricated into covalently bound self-assembled monolayers on the surfaces of fused silica and silicon. Spectroscopic second harmonic generation (SHG) measurements were carried out to determine the absolute value of the dominant element of the second-order nonlinear susceptibility, d33, and the average molecular alignment, ψ. We find a value of d33 = 60 pm/V at a fundamental wavelength of 890 nm, and ψ˜ 36° with respect to the surface normal.

scholarly journals A New Imaginary Term in the 2nd Order Nonlinear Susceptibility from Charged Interfaces

2021 ◽  
Author(s):  
Emily Ma ◽  
Jeongmin Kim ◽  
Yangdongling Liu ◽  
Emilie Lozier ◽  
Thomas Miller ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ionic Strength ◽  
Phase Shift ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Second Order ◽  
Nonlinear Susceptibility ◽  
Ion Specificity ◽  
Interfacial Processes ◽  
Point Estimates

<p>Non-resonant second harmonic generation phase and amplitude measurements obtained from the silica:water interface at varying pH and 0.5 M ionic strength point to the existence of a nonlinear susceptibility term, which we call , that is associated with a 90° phase shift. Including this contribution in a model for the total effective second-order nonlinear susceptibility produces reasonable point estimates for interfacial potentials and second-order nonlinear susceptibilities when . A model without this term and containing only traditional and terms cannot recapitulate the experimental data. The new model also provides a demonstrated utility for distinguishing apparent differences in the second-order nonlinear susceptibility when the electrolyte is NaCl vs MgSO<sub>4</sub>, pointing to the possibility of using HD-SHG to investigate ion-specificity in interfacial processes.</p>

scholarly journals A New Imaginary Term in the 2nd Order Nonlinear Susceptibility from Charged Interfaces

2021 ◽  
Author(s):  
Emily Ma ◽  
Jeongmin Kim ◽  
Yangdongling Liu ◽  
Emilie Lozier ◽  
Thomas Miller ◽  
...  
Keyword(s):  
Experimental Data ◽  
Ionic Strength ◽  
Phase Shift ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Second Order ◽  
Nonlinear Susceptibility ◽  
Ion Specificity ◽  
Interfacial Processes ◽  
Point Estimates

<p>Non-resonant second harmonic generation phase and amplitude measurements obtained from the silica:water interface at varying pH and 0.5 M ionic strength point to the existence of a nonlinear susceptibility term, which we call , that is associated with a 90° phase shift. Including this contribution in a model for the total effective second-order nonlinear susceptibility produces reasonable point estimates for interfacial potentials and second-order nonlinear susceptibilities when . A model without this term and containing only traditional and terms cannot recapitulate the experimental data. The new model also provides a demonstrated utility for distinguishing apparent differences in the second-order nonlinear susceptibility when the electrolyte is NaCl vs MgSO<sub>4</sub>, pointing to the possibility of using HD-SHG to investigate ion-specificity in interfacial processes.</p>

Radio-Frequency Probes in a Nonlinear Isotropic Plasma

1974 ◽  
Vol 52 (4) ◽  
pp. 291-301 ◽  
Author(s):  
Colin C. Bantin ◽  
Keith G. Balmain
Keyword(s):  
Radio Frequency ◽  
Cold Plasma ◽  
Nonlinear Response ◽  
Plasma Frequency ◽  
Second Harmonic ◽  
Second Order ◽  
Constant Current ◽  
Constant Voltage ◽  
Isotropic Plasma ◽  
Input Signals

Nonlinear cold-plasma and scalar-pressure theories are derived and applied to a spherical RF probe in a plasma. With two specified RF potentials on the probe at different frequencies, calculations are presented for the second-order probe output responses. These include the second harmonic, the sum and difference frequencies, and the d.c. increment (resonance rectification). The nonlinear response as a function of frequency is shown to depend strongly on whether the input signals are maintained at a constant current or a constant voltage; for diagnostics, the constant-current technique permits identification of the plasma frequency, whereas the constant-voltage technique does not.

scholarly journals Direct Measurement of Charge Reversal on Lipid Bilayers using Heterodyne-Detected Second Harmonic Generation Spectroscopy

2019 ◽  
Author(s):  
HanByul Chang ◽  
Paul Ohno ◽  
Yangdongling Liu ◽  
Emilie Lozier ◽  
Naomi Dalchand ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Surface Potential ◽  
Second Harmonic ◽  
Fluid Phase ◽  
Cationic Polyelectrolyte ◽  
Second Order ◽  
Nonlinear Susceptibility ◽  
Charge Reversal ◽  
Data Isolation ◽  
Order Susceptibility

<div><div><div><p>We report the detection of charge reversal induced by the adsorption of a cationic polyelectrolyte, poly(allylamine) hydrochloride (PAH), to buried supported lipid bilayers (SLBs), used as idealized model biological membranes. Through the use of an α-quartz reference crystal, we quantify the total interfacial potential at the interface in absolute units, using HD-SHG as an optical voltmeter in which the traditional wire leads of a voltmeter have been replaced by photons. This quantification is made possible by isolating from other contributions to the total SHG response the phase-shifted potential-dependent third-order susceptibility. We detect the sign and magnitude of the surface potential and the point of charge reversal at buried interfaces without prior information or complementary data. Isolation of the second-order susceptibility contribution from the overall SHG response allows us to directly characterize the Stern and Diffuse Layers over single-component SLBs formed from three different zwitterionic lipids of different gel-to-fluid phase transition temperatures (Tms). We determine whether the surface potential changes with the physical phase state (gel, transitioning, or fluid) of the SLB and incorporate 20 percent of negatively charged lipids to the zwitterionic SLB to investigate how the surface potential and the</p><p>second-order nonlinear susceptibility chi(2) change with surface charge.</p></div></div></div>

scholarly journals Direct Measurement of Charge Reversal on Lipid Bilayers using Heterodyne-Detected Second Harmonic Generation Spectroscopy

2019 ◽  
Author(s):  
HanByul Chang ◽  
Paul Ohno ◽  
Yangdongling Liu ◽  
Emilie Lozier ◽  
Naomi Dalchand ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Surface Potential ◽  
Second Harmonic ◽  
Fluid Phase ◽  
Cationic Polyelectrolyte ◽  
Second Order ◽  
Nonlinear Susceptibility ◽  
Charge Reversal ◽  
Data Isolation ◽  
Order Susceptibility

<div><div><div><p>We report the detection of charge reversal induced by the adsorption of a cationic polyelectrolyte, poly(allylamine) hydrochloride (PAH), to buried supported lipid bilayers (SLBs), used as idealized model biological membranes. Through the use of an α-quartz reference crystal, we quantify the total interfacial potential at the interface in absolute units, using HD-SHG as an optical voltmeter in which the traditional wire leads of a voltmeter have been replaced by photons. This quantification is made possible by isolating from other contributions to the total SHG response the phase-shifted potential-dependent third-order susceptibility. We detect the sign and magnitude of the surface potential and the point of charge reversal at buried interfaces without prior information or complementary data. Isolation of the second-order susceptibility contribution from the overall SHG response allows us to directly characterize the Stern and Diffuse Layers over single-component SLBs formed from three different zwitterionic lipids of different gel-to-fluid phase transition temperatures (Tms). We determine whether the surface potential changes with the physical phase state (gel, transitioning, or fluid) of the SLB and incorporate 20 percent of negatively charged lipids to the zwitterionic SLB to investigate how the surface potential and the</p><p>second-order nonlinear susceptibility chi(2) change with surface charge.</p></div></div></div>

Second-order classical nonlinear response theory

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 962-965
Author(s):  
Abdulmuhsen H. Ali
Keyword(s):  
Nonlinear Response ◽  
Second Order ◽  
Response Theory

scholarly journals Spectral Broadening in a Continuously Pumped Singly Resonant Second-Harmonic Cavity

2021 ◽  
Vol 11 (15) ◽  
pp. 7122
Author(s):  
Simona Mosca ◽  
Tobias Hansson ◽  
Maria Parisi
Keyword(s):  
Continuous Wave ◽  
Frequency Comb ◽  
Second Harmonic ◽  
Input Power ◽  
Second Order ◽  
Optical Frequency ◽  
Frequency Combs ◽  
Research Areas ◽  
Mixed Regime ◽  
Wide Range

Optical frequency comb synthesizers with a wide spectral range are an essential tool for many research areas such as spectroscopy, precision metrology, optical communication, and sensing. Recent studies have demonstrated the direct generation of frequency combs, via second-order processes, that are centered on two different spectral regions separated by an octave. Here, we present the capability of optical quadratic frequency combs for broad-bandwidth spectral emission in unexplored regimes. We consider comb formation under phase-matched conditions in a continuous-wave pumped singly resonant second-harmonic cavity, with large intracavity power and control of the detuning over several cavity line widths. The spectral analysis reveals quite distinctive sidebands that arise far away from the pump, singularly or in a mixed regime together with narrowband frequency combs. Notably, by increasing the input power, the optical frequency lines evolve into widely spaced frequency clusters, and at maximum power, they appear in a wavelength range spanning up to 100 nm. The obtained results demonstrate the power of second-order nonlinearities for direct comb production within a wide range of pump wavelengths.

Enhancement of second harmonic generation using a novel asymmetric metal–graphene–insulator–metal plasmonic waveguide

2018 ◽  
Vol 27 (01) ◽  
pp. 1850003 ◽  
Author(s):  
Mohamadreza Soltani
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Nonlinear Optical ◽  
Second Harmonic ◽  
Field Enhancement ◽  
The Other ◽  
Nonlinear Susceptibility ◽  
Optical Process ◽  
Large Enhancement ◽  
Nonlinear Optical Process

Here, we propose a novel plasmonic structure, called asymmetric plasmonic nanocavity grating (APNCG), which is shown to dramatically enhance nonlinear optical process of second harmonic generation (SHG). The proposed structure consists of two different metals on both sides of lithium niobate and a thin layer of graphene. By using two different metals the nonlinear susceptibility of the waveguide would be increased noticeably causing to increase SHG. On the other hand, it consists of two identical gratings on one side. By two identical gratings, the pump beam is coupled to two opposing SPP waves, which interfere with each other and result in SPP standing wave in the region between the two gratings. The distance between two gratings will be optimized to reach the highest SHG. It will be shown that by optimizing the geometry of proposed structure and using different metals, field enhancement in APNCG waveguides can result in large enhancement of SHG.

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