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Enhancing the Speed and Sensitivity of a Nonlinear Optical Sensor with Noise
摘要： We demonstrate how noise can be turned into a resource for optical sensing using a nonlinear cavity. The cavity is driven by a continuous-wave laser into the regime of optical bistability. Due to the influence of fluctuations, the cavity switches randomly between two metastable states. By analyzing the residence times in these two states, perturbations to the resonance frequency of the cavity can be detected. Here, such an analysis is presented as a function of the strength of the perturbation and of the noise. By increasing the standard deviation of the noise, we find that the detection speed increases monotonically while the sensitivity peaks at a finite value of the noise strength. Furthermore, we discuss how noise-assisted sensing can be optimized in state-of-the-art experimental platforms, relying solely on the minimum amount of noise present in the cavity due to its dissipation. These results open up new perspectives for the ultrafast detection of nanoparticles, contaminants, gases, or other perturbations to the resonance frequency of an optical resonator, at low powers and in noisy environments.
关键词： noise,residence times,nonlinear optical sensor,sensitivity,optical bistability,detection speed
更新于2025-09-23 15:19:57
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Externally controlled Lotka-Volterra dynamics in a linearly polarized polariton fluid
摘要： Spontaneous formation of transverse patterns is ubiquitous in nonlinear dynamical systems of all kinds. An aspect of particular interest is the active control of such patterns. In nonlinear optical systems this can be used for all-optical switching with transistorlike performance, for example, realized with polaritons in a planar quantum-well semiconductor microcavity. Here we focus on a specific configuration which takes advantage of the intricate polarization dependencies in the interacting optically driven polariton system. Besides detailed numerical simulations of the coupled light-field exciton dynamics, in the present paper we focus on the derivation of a simplified population competition model giving detailed insight into the underlying mechanisms from a nonlinear dynamical systems perspective. We show that such a model takes the form of a generalized Lotka-Volterra system for two competing populations explicitly including a source term that enables external control. We present a comprehensive analysis of both the existence and stability of stationary states in the parameter space spanned by spatial anisotropy and external control strength. We also construct phase boundaries in nontrivial regions and characterize emerging bifurcations. The population competition model reproduces all key features of the switching observed in full numerical simulations of the rather complex semiconductor system and at the same time is simple enough for a fully analytical understanding.
关键词： all-optical switching,population competition model,nonlinear optical systems,transverse patterns,Lotka-Volterra system,polaritons,semiconductor microcavity
更新于2025-09-23 15:19:57
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Linear-nonlinear optical, dielectric and surface microscopic investigation of KH2PO4 crystal to uncover the decisive impact of dopant glycine
摘要： Present investigation has been started to perform the comparative study of pure and glycine doped KH2PO4 (KDP) single crystals grown by most commercial slow solvent evaporation technique. The grown crystals were subjected to single crystal X-ray diffraction analysis to determine their structural parameters. The linear optical studies of pure and glycine doped KDP crystal have been undertaken within 200 nm to 1100 nm wavelength range by means of UV-Vis studies. The enhancement in second harmonic generation (SHG) ef?ciency of glycine doped KDP crystal has been determined using a standard Kurtz-Perry powder test. The dielectric measurements have been carried out to explore the impact of glycine dopant on dielectric constant and dielectric loss of KDP crystal. The surface growth habitat and etch pit density of glycine doped KDP crystal have been evaluated using the results of microscopic etching studies. In light of obtained results the suitability of glycine doped KDP crystal for device applications has been discussed.
关键词： optical studies,etching studies,crystal growth,dielectric studies,nonlinear optical materials
更新于2025-09-23 15:19:57
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Prediction of MCO [M = S, (Cl <sub/>2</sub> B) <sub/>3</sub> B] Systems with Giant Optical Birefringence and Nonlinearity in the Deep-Ultraviolet Region
摘要： Deep-ultraviolet (DUV) materials with giant optical birefringence and nonlinearity are scarce, and their discovery is very challenging. In this Communication, we predict that the MCO [M = S, (Cl2B)3B] compounds containing the polar C?O motif, which have been synthesized in the experiments, could be the ?rst material systems to achieve this rare capability. First-principles calculations demonstrate that (Cl2B)3BCO and SCO exhibit the largest second-harmonic-generation e?ect (～4.4 pm/V) and the largest birefringence (～0.6) in all known DUV nonlinear-optical (NLO) crystals. In addition, SCO might be a DUV NLO material for the practical 193.7 nm laser output. Our discovery could enrich the structural chemistry of NLO crystals and advance the development of functional DUV optical materials.
关键词： Deep-ultraviolet,nonlinearity,polar C?O motif,DUV nonlinear-optical crystals,first-principles calculations,MCO compounds,second-harmonic-generation,optical birefringence
更新于2025-09-23 15:19:57
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Magnetoa??optical specifications of Rosena??Morse quantum dot with screw dislocation
摘要： This is the first study to consider a quantum dot with screw dislocation that has Rosen-Morse (RM) confinement potential, generated by a GaAs/GaAlAs heterostructure. An external magnetic field and Aharonov-Bohm (AB) flux field were also applied on RM quantum dot (RMQD) in order to stave the effects of a screw dislocation defect. The combined effect of the screw dislocation defect, the external magnetic field, and AB flux field on the total refractive index changes (TRICs) and the total absorption coefficients (TACs) of RMQD are thus investigated. Cylindrical coordinates are used due to the direction of application of the torsion and the external fields, as well as due to the structure's symmetry. The effective mass approximation and tridiagonal matrix methods are used in order to obtain the subband energy spectra and electronic wave functions of RMQD. The nonlinear optical specifications of RMQD are checked using compact-density-matrix formalism within the framework of the iterative method. Reviews without screw dislocation are also carried out in order to be able to clarify the effects of a screw dislocation defect on the optical properties, and then, both cases are deliberated. This study is the first attempt to analyze the AB flux field for RMQD without screw dislocation. In the present study, the influences of a screw dislocation defect on RMQD's TRICs and TACs are probed by considering different values of the external magnetic field and AB flux field, and the ranges of corresponding parameters on the optimum of the structure are specified. Moreover, the study also elucidates how to rule out the effects of screw dislocation on optical specifications by means of the external fields. Despite a certain screw dislocation, the frequency range is determined where the structure behaves as if it is perfect (namely, without screw dislocation) for its optimum, which in turn is crucial for experimental applications.
关键词： quantum dot,magnetic field,screw dislocation,Aharonov-Bohm flux field,nonlinear optical properties
更新于2025-09-23 15:19:57
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Spectral analysis combined with nonlinear optical measurement of laser printed biopolymer composites comprising chitosan/SWCNT
摘要： Biopolymer composites based on two types of chitosan (chitosan succinate and low-molecular weight chitosan) with single-walled carbon nanotubes (SWCNT) were created by laser printing. SWCNT have good dispersibility in chitosan solutions and therefore, can form relatively homogeneous films that was shown in scanning electron microscopy images. For the studies film composites were formed under the action of laser radiation on aqueous dispersion media. Study of the nonlinear optical process during the interaction of laser radiation with a disperse media has shown that low-molecular chitosan has a large nonlinear absorption coefficient of 17 cm/GW, while the addition of SWCNT lead to a significant increase up to 902 cm/GW. The threshold intensity for these samples was 5.5 MW/cm2 with nanotubes. If intensity exceeds the threshold value, nonlinear effects occur, which, in turn, lead to the transformation of a liquid into a solid phase. Characterization of films by FTIR and Raman spectroscopy indicated arising molecular interactions between chitosan and SWCNT detected as a small frequency shift and a change in the shape of radial breathing mode (RBM). The results indicate the possibility using aqueous dispersion media based on chitosan and SWCNT to create three-dimensional films and scaffolds for tissue engineering by laser printing.
关键词： Tissue engineering,Carbon nanotubes,Nonlinear optical properties,Chitosan,Spectroscopy
更新于2025-09-23 15:19:57
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Nonlinear optical rectification and electronic structure in asymmetric coupled quantum wires
摘要： Asymmetric coupled quantum wires provide the possibility for realizing obvious nonlinear optical rectification due to breaking the inversion symmetry. Here, we investigated nonlinear optical rectification (NOR) and electronic states in asymmetric coupled quantum wires (ACQWs). We find that the NOR max value of the ACQWs exhibits double peak structure with the increase of the geometrical asymmetry (i.e. the left wire radius deviating from the right wire radius), thus offering a direction for achieving remarkable NORS. In the double peak structure, the max value is one to two orders of magnitude larger than the min value. Furthermore, we find that the tunneling effect with respect to the ground state is reduced with the increase of the geometrical asymmetry, while the tunneling effect with respect to the first-excited state is firstly reduced, subsequently enhanced and then reduced with the increase of the geometrical asymmetry. Such coupling pictures elucidate the double peak structure in the NOR max value of the ACQWs. Our work enriches our understanding for the NOR and quantum states of the ACQWs, thereby laying the groundwork for the design and optimization of nonlinear nano-optical devices based on asymmetric coupled quantum wires such as THz radiation sources and infrared photo-detectors.
关键词： Asymmetric coupled quantum wires,Electronic structure,Nonlinear optical rectification
更新于2025-09-23 15:19:57
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Polar coupling enabled nonlinear optical filtering at MoS2/ferroelectric heterointerfaces
摘要： Complex oxide heterointerfaces and van der Waals heterostructures present two versatile intrinsically different platforms for exploring emergent quantum phenomena and designing new functionalities. The rich opportunity offered by the synergy between these two classes of materials, however, is yet to be charted. Here, we report an unconventional nonlinear optical filtering effect resulting from the interfacial polar alignment between monolayer MoS2 and a neighboring ferroelectric oxide thin film. The second harmonic generation response at the heterointerface is either substantially enhanced or almost entirely quenched by an underlying ferroelectric domain wall depending on its chirality, and can be further tailored by the polar domains. Unlike the extensively studied coupling mechanisms driven by charge, spin, and lattice, the interfacial tailoring effect is solely mediated by the polar symmetry, as well explained via our density functional theory calculations, pointing to a new material strategy for the functional design of nanoscale reconfigurable optical applications.
关键词： nonlinear optical filtering,second harmonic generation,MoS2/ferroelectric heterointerfaces,density functional theory,polar symmetry
更新于2025-09-23 15:19:57
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Passively Q-switched near-infrared lasers with bismuthene quantum dots as the saturable absorber
摘要： Bismuthene quantum dots (Bi-QDs) were synthesized via the liquid phase exfoliation (LPE) method for the passive Q-switching operation in near-infrared (NIR) region. The nonlinear optical properties of the prepared Bi-QDs were investigated by the open-aperture Z-scan technology. The modulation depths were 18.1% and 5.1% at 1.06 and 1.34 μm, respectively. Based on the Bi-QDs saturable absorber, passively Q-switched Nd:GdVO4 lasers operating at 4F3/2 → 2I11/2 and 4F3/2 → 2I13/2 transitions were demonstrated, showing the wideband optical modulation in NIR regime. For the 4F3/2 → 2I13/2 transition lasing at 1.34 μm, the shortest pulse duration of 155 ns was obtained with a repetition rate of 457 kHz. With respect to the 4F3/2 → 2I11/2 transition at 1.06 μm, the minimum pulse duration was 150 ns with a repetition rate of 424 kHz, leading to a single pulse energy of 261 nJ and a peak power of 1.68 W. In addition, the ground state absorption cross section and the excited state absorption cross section of Bi-QDs were also investigated for the ?rst time. The impact of the excited state lifetime on the output parameters was numerically stimulated by the coupled rate equations. Our work con-?rmed that the trap state in Bi-QDs played an important role in the pulse generation mechanism.
关键词： Saturable absorber,Bismuthene quantum dots,Q-switching,Nonlinear Optical properties,Rate equations
更新于2025-09-23 15:19:57
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Plasmonic Nanoparticles in Dielectrics Synthesized by Ion Beams: Optical Properties and Photonic Applications
摘要： The zero-dimensional metallic nanoparticles (NPs) have attracted tremendous attention in various areas owing to the collective oscillation of electron gas that couples with electromagnetic field, known as localized surface plasmon resonance (LSPR). In practical applications, the tailoring of LSPR effect is of significant importance for promising photonic devices with designed nanocomposite systems and enhanced optical properties. Ion beam technology has been demonstrated to be an efficient method to fabricate NPs embedded in dielectrics for LSPR tailoring and material modification. By manipulating the parameters of ion beams, the shape, size, and structure of NPs can be well controlled, which enables the dielectrics to possess novel linear and nonlinear optical properties. In this review, the latest research progress on the ion beam synthesis of various NPs is systematically summarized. The tailoring of linear and nonlinear optical properties of dielectrics by NPs is discussed in detail. Selected applications are presented to indicate the development of the plasmonic NPs in dielectric systems for photonic applications.
关键词： localized surface plasmon resonance,ion beam modification,nonlinear optical responses,photonic applications,plasmonic nanoparticles
更新于2025-09-23 15:19:57