Semiconductor Resonators Research Articles

Vibrational Fermi Resonance in Atomically Thin Black Phosphorus.

Fermi resonance is a phenomenon involving the hybridization of two coincidentally quasi-degenerate states that is observed in the vibrational or electronic spectra of molecules. Despite numerous examples in molecular systems, vibrational Fermi resonances in dispersive semiconducting systems remain largely unexplored due to the rarity of occurrence. Here we report a vibrational Fermi resonance in atomically thin black phosphorus. The Fermi resonance arises via anharmonic mixing of a fundamental Raman mode and a Davydov component of an infrared mode, leading to a doublet with mixed character. The extent of Fermi coupling can be modulated by the application of external biaxial strain. The consequences of Fermi hybridization are revealed by electronic resonance effects in the thickness-dependent and excitation-wavelength-dependent Raman spectrum, which is predicted by ab initio hybrid functional simulations including excitonic interactions. This work reveals new insight into electron-phonon coupling in black phosphorus and demonstrates a novel method for modulating Fermi resonances in 2D semiconductors.

Measuring the Electronic Bandgap of Carbon Nanotube Networks in Non-Ideal p-n Diodes.

The measurement of the electronic bandgap and exciton binding energy in quasi-one-dimensional materials such as carbon nanotubes is challenging due to many-body effects and strong electron-electron interactions. Unlike bulk semiconductors, where the electronic bandgap is well known, the optical resonance in low-dimensional semiconductors is dominated by excitons, making their electronic bandgap more difficult to measure. In this work, we measure the electronic bandgap of networks of polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWCNTs) using non-ideal p-n diodes. We show that our s-SWCNT networks have a short minority carrier lifetime due to the presence of interface trap states, making the diodes non-ideal. We use the generation and recombination leakage currents from these non-ideal diodes to measure the electronic bandgap and excitonic levels of different polymer-wrapped s-SWCNTs with varying diameters: arc discharge (~1.55 nm), (7,5) (0.83 nm), and (6,5) (0.76 nm). Our values are consistent with theoretical predictions, providing insight into the fundamental properties of networks of s-SWCNTs. The techniques outlined here demonstrate a robust strategy that can be applied to measuring the electronic bandgaps and exciton binding energies of a broad variety of nanoscale and quantum-confined semiconductors, including the most modern nanoscale transistors that rely on nanowire geometries.

Optical Electron-Nuclear Resonance in Semiconductors

A considerable number of investigations have by now been made on optical pumping of spin-oriented electrons in semiconductors. The optical-pumping method makes it possible to produce easily a high polarization of the electron spins in the conduction band, and to detect it optically [1–3]. The use of this method for the investigation of semiconductors turned out to be very fruitful; the spin orientation of the minority [1–3] and majority [4] carriers was determined, the lifetimes of the non-equilibrium electrons were measured [2, 3, 5], the mechanisms of spin relaxation of “cold” [2, 5] and “hot” [2, 6] electrons were investigated, spin orientation of excitons was effected [7], and electron paramagnetic resonance with non-equilibrium electrons was registered [8].

Multiple‐Resonance‐Enhanced Raman Spectroscopy in 2D‐Material‐Capped Tapered‐Fiber Microcavity

AbstractPlasmon‐free surface‐enhanced Raman spectroscopy (SERS) assisted by charge‐transfer (CT) resonance in semiconductors has drawn considerable attention in the past decades due to the extraordinary advantages in chemical stability and homogeneity. Unfortunately, the weak confinement of excitation light in semiconductor nanostructures and 2D materials, due to either their limited refractive indexes or atomic thickness, results in the Raman enhancement by nonmetallic SERS substrates significantly lower than the noble ones. Here a novel plasmon‐free SERS probe is reported by a tapered optical fiber (TOF) coated with monolayer‐MoS2 (ML‐MoS2), where the TOF‐supported whispering‐gallery modes (WGMs) simultaneously regulate multiple‐resonance processes, i.e., excitonic resonance, molecular resonance, charge‐transfer resonance and fluorescence resonance energy transfer processes, in the ML‐MoS2 and analytes. The contribution of the four processes promoted by WGM to enhancement factor of Raman intensity (EFRI) is quantitatively determined by four dye molecules with different energy levels. The Raman enhancement mechanism of WGM‐promoted multiple‐resonances is therefore revealed, for the first time. The maximum EFRI is up to 1.8 × 109 for the limit of detection (LoD) down to 10−14 M. The ML‐MoS2/TOF SERS probes also demonstrated their outstanding feasibility and stability facilitating to trace detection in microdroplets for practical applications in future.

Temperature-resilient anapole modes associated with TE polarization in semiconductor nanowires

Polarization-dependent scattering anisotropy of cylindrical nanowires has numerous potential applications in, for example, nanoantennas, photothermal therapy, thermophotovoltaics, catalysis, sensing, optical filters and switches. In all these applications, temperature-dependent material properties play an important role and often adversely impact performance depending on the dominance of either radiative or dissipative damping. Here, we employ numerical modeling based on Mie scattering theory to investigate and compare the temperature and polarization-dependent optical anisotropy of metallic (gold, Au) nanowires with indirect (silicon, Si) and direct (gallium arsenide, GaAs) bandgap semiconducting nanowires. Results indicate that plasmonic scattering resonances in semiconductors, within the absorption band, deteriorate with an increase in temperature whereas those occurring away from the absorption band strengthen as a result of the increase in phononic contribution. Indirect-bandgap thin ([Formula: see text]) Si nanowires present low absorption efficiencies for both the transverse electric (TE, [Formula: see text]) and magnetic (TM, [Formula: see text]) modes, and high scattering efficiencies for the TM mode at shorter wavelengths making them suitable as highly efficient scatterers. Temperature-resilient higher-order anapole modes with their characteristic high absorption and low scattering efficiencies are also observed in the semiconductor nanowires ([Formula: see text] nm) for the TE polarization. Herein, the GaAs nanowires present [Formula: see text] times greater absorption efficiencies compared to the Si nanowires making them especially suitable for temperature-resilient applications such as scanning near-field optical microscopy (SNOM), localized heating, non-invasive sensing or detection that require strong localization of energy in the near field.

Enhanced Cavity Optomechanics with Quantum-Well Exciton Polaritons.

Semiconductor microresonators embedding quantum wells can host tightly confined and mutually interacting excitonic, optical, and mechanical modes at once. We theoretically investigate the case where the system operates in the strong exciton-photon coupling regime, while the optical and excitonic resonances are parametrically modulated by the interaction with a mechanical mode. Owing to the large exciton-phonon coupling at play in semiconductors, we predict an enhancement of polariton-phonon interactions by 2 orders of magnitude with respect to mere optomechanical coupling: a near-unity single-polariton quantum cooperativity is within reach for current semiconductor resonator platforms. We further analyze how polariton nonlinearities affect dynamical backaction, modifying the capability to cool or amplify the mechanical motion.

Study of the Electronic Defect States of One-Dimensional Comb-like Quantum Wires Structure with Resonator Defect by Using the Transfer Matrix Method

In this paper using the transfer matrix method (TMM), we consider an electronic comb-like waveguides system composed by the periodicity of segment semiconductor (GaAs type) of length and grafted in its extremity by one semiconductor resonator (GaAlAs type) of length . These segments and resonators are considered quantum wires. The perfect system in question presents the electronic pass bands and electronic band gaps which allow to control and manipulate the electrons waves whose energy is identical to the energy of the gaps. We insert the defect at the resonator level in the middle of this system in question. Hence, very narrow localized defect states are created in the electronic band gaps, with probably high transmission rate and very important quality factor. These localized defect states shift to low energy by increasing the resonator defect length, while is move to high energy when the resonator defect concentration increases. In this study, we consider that the segments and resonators lengths are very small in front of their sections, so that the propagation of electronic waves occurs only in a single dimension.

Excitation of tunable plasmons in silicon using microwave transmission through a metallic aperture

Plasmon resonances in semiconductors at microwave frequencies offer the possibility for many functionalities and integration schemes. Semiconductor materials, such as germanium, gallium arsenide, and silicon, have the further advantage of being able to be integrated with standard electronics technology. Here, we probe the bulk plasmon modes in silicon in the vicinity of a copper plate perforated by a single aperture at frequencies between 10 and 60 GHz. Sharp transmission minima are observed at discrete frequencies. The observed frequencies depend on the size of the aperture and the carrier concentration in the silicon; they are well reproduced by the dispersion relation for bulk plasmons. Our results show that one can excite plasmons in silicon in the millimeter-wave region, opening a route to microwave plasmonics for large-scale applications, using low-cost technology.

Cost-Effective Bull's Eye Aperture-Style Multi-Band Metamaterial Absorber at Sub-THz Band: Design, Numerical Analysis, and Physical Interpretation.

Theoretical and numerical studies were conducted on plasmonic interactions at a polarization-independent semiconductor–dielectric–semiconductor (SDS) sandwiched layer design and a brief review of the basic theory model was presented. The potential of bull’s eye aperture (BEA) structures as device elements has been well recognized in multi-band structures. In addition, the sub-terahertz (THz) band (below 1 THz frequency regime) is utilized in communications and sensing applications, which are in high demand in modern technology. Therefore, we produced theoretical and numerical studies for a THz-absorbing-metasurface BEA-style design, with N-beam absorption peaks at a sub-THz band, using economical and commercially accessible materials, which have a low cost and an easy fabrication process. Furthermore, we applied the Drude model for the dielectric function of semiconductors due to its ability to describe both free-electron and bound systems simultaneously. Associated with metasurface research and applications, it is essential to facilitate metasurface designs to be of the utmost flexible properties with low cost. Through the aid of electromagnetic (EM) coupling using multiple semiconductor ring resonators (RRs), we could tune the number of absorption peaks between the 0.1 and 1.0 THz frequency regime. By increasing the number of semiconductor rings without altering all other parameters, we found a translation trend of the absorption frequencies. In addition, we validated our spectral response results using EM field distributions and surface currents. Here, we mainly discuss the source of the N-band THz absorber and the underlying physics of the multi-beam absorber designed structures. The proposed microstructure has ultra-high potentials to utilize in high-power THz sources and optical biomedical sensing and detection applications based on opto-electronics technology based on having multi-band absorption responses.

Simulation on parameter optimization of gold nano-antenna attached to semiconductor ring resonator for heat-assisted magnetic recording device

Simulation on parameter optimization of gold nano-antenna attached to semiconductor ring resonator for heat-assisted magnetic recording device

Electrically tunable Feshbach resonances in twisted bilayer semiconductors.

Moiré superlattices in transition metal dichalcogenide bilayers provide a platform for exploring strong correlations with optical spectroscopy. Despite the observation of rich Mott-Wigner physics stemming from an interplay between the periodic potential and Coulomb interactions, the absence of tunnel coupling–induced hybridization of electronic states has ensured a classical layer degree of freedom. We investigated a MoSe2 homobilayer structure where interlayer coherent tunneling allows for electric field–controlled manipulation and measurement of the ground-state hole-layer pseudospin. We observed an electrically tunable two-dimensional Feshbach resonance in exciton-hole scattering, which allowed us to control the strength of interactions between excitons and holes located in different layers. Our results may enable the realization of degenerate Bose-Fermi mixtures with tunable interactions.

Simulation on parameter optimization of semiconductor ring resonator with nano-antenna for heat-assisted magnetic recording device

Simulation on parameter optimization of semiconductor ring resonator with nano-antenna for heat-assisted magnetic recording device

Electro-Optomechanical Modulation Instability in a Semiconductor Resonator

In semiconductor nano-optomechanical resonators, several forms of light-matter interaction can enrich the canonical radiation pressure coupling of light and mechanical motion and give rise to new dynamical regimes. Here, we observe an electro-optomechanical modulation instability in a gallium arsenide disk resonator. The regime is evidenced by the concomitant formation of regular and dense combs in the radio-frequency and optical spectrums of the resonator associated with a permanent pulsatory dynamics of the mechanical motion and optical intensity. The mutual coupling between light, mechanical oscillations, carriers, and heat, notably through photothermal interactions, stabilizes an extended mechanical comb in the ultrahigh frequency range that can be controlled optically.

Ultrafast all-optical diffraction switching using semiconductor metasurfaces

Ultrafast all-optical switching using Mie resonant metasurfaces requires both on-demand tunability of the wavefront of the light and ultrafast time response. However, devising a switching mechanism that has a high contrast between its “on” and “off” states without compromising speed is challenging. Here, we report the design of a tunable Mie resonant metasurface that achieves this behavior. Our approach utilizes a diffractive array of semiconductor resonators that support both dipolar and quadrupolar Mie resonances. By balancing the strengths of the dipole and quadrupole resonances, we can suppress radiation into the first diffraction order, thus creating a clearly delineated “off”-state at the operating wavelength. Then, we use optical injection of free- carriers to spectrally shift the multipoles and rebalance the multipole strengths, thereby enabling radiation into the diffraction order—all on an ultrafast timescale. We demonstrate ultrafast off-to-on switching with Ion/Ioff ≈ 5 modulation of the diffracted intensity and ultrafast on-to-off switching with Ion/Ioff ≈ 9 modulation. Both switches exhibit a fast τtr ≈ 2.7 ps relaxation time at 215 μJ cm−2 pump fluence. Further, we show that for higher fluences, the temporal response of the metasurface is governed by thermo-optic effects. This combination of multipole engineering with lattice diffraction opens design pathways for tunable metasurface-based integrated devices.

Coherent control of quantum and entanglement dynamics via periodic modulations in optomechanical semiconductor resonator coupled to quantum-dot excitons

We systematically study the influence of simultaneously modulating the input laser intensity and quantum-dot (QD) resonance frequency on the mean-field dynamics, fluctuation energy transfer and entanglement in a optomechanical semiconductor resonator embedded with a QD. We show that the modulation and the hybrid system can be engineered to attain the desired mean-field values and control the fluctuation energy transfer and the entanglement among the various degrees of freedom. A remarkably high degree of entanglement can be generated by modulating only the QD frequency. The interplay between the two modulations leads to a decrease in the entanglement. Switching on the modulation leads to a transition from low stationary to large dynamical entanglement. This investigation provides novel strategies to coherently control data signal transfer and storage in quantum information processing networks.

Simulation on near-field light on recording medium generated by semiconductor ring resonator with metal nano-antenna for heat-assisted magnetic recording

Heat-assisted magnetic recording (HAMR) is a promising technology for achieving more than 10 Tbit/inch2 recording density. A near-field transducer (NFT), which forms a small light spot on a recording medium, is necessary in HAMR. However, the heat generated by the NFT would melt the NFT itself. To solve this problem, the authors have proposed a novel device, in which a metal nano-antenna is attached to a semiconductor ring resonator. In this paper, the near-field light generated by this device was analyzed through a numerical simulation based on a 3-dimensional model including the recording medium to optimize the structure of the device. It was found that how to excite a desired eigenmode selectively among some eigenmodes is important to make the device effective. A light spot with a diameter of about 25 nm, which corresponds to the recording density of 1 Tb/inch2, was obtained on the surface of the recording medium. It was also found that the design parameters of the device must be optimized considering the recording medium.

Colloid templated semiconductor meta-surface for ultra-broadband solar energy absorber

In this work, a thin semiconductor void resonators meta-surface is theoretically proposed and numerically demonstrated as a novel platform for perfect solar absorber. The absorber exhibits an ultra-broadband perfect absorption in the visible and infrared range. In comparison with the noble metals coupled absorbers, it is observed that the introduced titanium substrate produces a strong enhancement (90%) of the spectral absorption for the Ge resonators in a wide spectral window from 1.283 μm to 2.830 μm. As for the actual solar light absorption measurement, the spectrally weighted solar energy absorption efficiency is up to 88% for this semiconductor material based plasmonic absorber in the whole sun irradiation range (280–4000 nm). The absorption behaviors can be artificially manipulated via tuning the structural parameters. Photonic resonant modes in the semiconductor resonators and the plasmonic resonances of the titanium material are the main contributions for the excellent absorption response. In sharp contrast to the metal-insulator absorber, the herein absorber platform can hold three main advantages on the optoelectronic responses by the active semiconductor resonators, the broadband or full-spectrum solar perfect absorption in the semiconductor/titanium composite system, and the stronger thermal stability by the refractory titanium metal.

Optical Phase Transition in Semiconductor Quantum Metamaterials.

Unexpected light propagation effects, such as negative refraction, have been reported in artificial media. Leveraging on the intersubband resonances in heterostructured semiconductors, we show that all possible optical regimes, ranging from classical dieletric and metal to hyperbolic metamaterial types 1 and 2, can be achieved. As a demonstration, we prove that the negative refraction effect can occur at a designed frequency by controlling the electronic quantum confinement.

Magnetization dynamics and related phenomena in semiconductors with ferromagnetism

We review ferromagnetic resonance (FMR) and related phenomena in the ferromagnetic semiconductor (Ga,Mn)As and single crystalline Fe/GaAs (001) hybrid structures. In both systems, spin-orbit interaction is the key ingredient for various intriguing phenomena.

Simulation on near-field light generated by a semiconductor ring resonator with a metal nano-antenna for heat-assisted magnetic recording

Heat-assisted magnetic recording (HAMR) is a promising technology for achieving more than 1 Tbit/inch2 recording density. A near-field transducer (NFT), which forms a small light spot on a recording medium, is necessary in HAMR. However, the heat generated by the NFT would melt the NFT itself. To solve this problem, the authors have proposed a novel device, in which a metal nano-antenna is attached to a semiconductor ring resonator. In this paper, the relationship between the various design parameters of the device and the near-field light was investigated through a numerical simulation to optimize the structure of the device. The simulation was conducted using the finite element method based on a two-dimensional model. It was found that the electric field at the tip of the nano-antenna depends on the type of eigenmode, the length of the nano-antenna, and the distance between the ring resonator and the nano-antenna.