Cavity Semiconductor Research Articles

Enhanced Biosensing with Double Gate Junctionless FET based on III–V Compound Semiconductor and Symmetric Cavity for Label-Free Detection of Neutral and Charged Biomolecules

Enhanced Biosensing with Double Gate Junctionless FET based on III–V Compound Semiconductor and Symmetric Cavity for Label-Free Detection of Neutral and Charged Biomolecules

Disordered plasmonic nanocavity enhanced quantum dot emission

In this paper, a large-scale compatible plasmonic nanocavity design platform is utilized to achieve a nearly order of magnitude photoluminescence (PL) enhancement. The proposed design is made of multi-sized/multi-spacing gold (Au) nanounits that are uniformly wrapped with a thin aluminum oxide (Al2O3) layer, as a foreign host to form a metal–insulator–semiconductor cavity, as they are coated with semiconductor quantum dots (QDs). Our numerical and experimental data demonstrate that, in an optimal insulator layer thickness, the simultaneous formation of broadband Fabry–Perot resonances and plasmonic hot spots leads to enhanced light absorption within the QD unit. This improvement in absorption response leads to the PL enhancement of QDs. This work demonstrates the potential and effectiveness of a random plasmonic nanocavities host in the realization of lithography-free efficient emitters.

Photon Bose–Einstein Condensation and Lasing in Semiconductor Cavities

AbstractPhoton Bose–Einstein condensation and photon thermalisation have been largely studied with molecular gain media in optical cavities. However, their observation with semiconductors has remained elusive despite a large body of experimental results and very well established theoretical models. In this work, these models are used to build a new theoretical framework that enables revisiting lasing to compare with photon Bose–Einstein condensation in the driven‐dissipative regime. The thermalisation figures of merit and the different experimental procedures to asses thermalization are discussed. Finally, the fluctuations of the system and their relation to the different regimes are explored.

Quantum Statistical and Squeezing Properties in a Semiconductor Cavity QED

Quantum Statistical and Squeezing Properties in a Semiconductor Cavity QED

Athermalization of the Lasing Wavelength in Vertical‐Cavity Surface‐Emitting Lasers

AbstractA concept for vertical‐cavity surface‐emitting lasers (VCSELs) is proposed and demonstrated to obtain a lasing wavelength with unprecedented temperature stability. The concept is based on incorporating a dielectric material with a negative thermo‐optic coefficient, dn/dT, in the distributed Bragg reflectors (DBRs) to compensate the positive dn/dT of the semiconductor cavity. In a short cavity, the optical field has a significant overlap with the DBRs, and the redshift of the lasing wavelength caused by the semiconductor cavity can be compensated by the negative dn/dT of the DBRs. Here, proof of this concept is presented for optically‐pumped VCSELs emitting at 310 nm, demonstrating a lasing wavelength that even blueshifts by less than 0.1 nm over an 80 °C range with a maximum slope of –3.4 pm K−1. This is to be compared with a redshift of 1–1.5 nm over the same temperature range reported for III‐nitride blue‐emitting VCSELs. Furthermore, this method can also be implemented in VCSELs with longer cavity lengths by including a dielectric layer between the semiconductor and the DBR. The approach used here to obtain a temperature‐stable lasing wavelength is generic and can therefore be applied to VCSELs in all material systems and lasing wavelengths.

Reservoir optics with exciton-polariton condensates

We investigate an all-optical microscale planar lensing technique based on coherent fluids of semiconductor cavity exciton-polariton condensates. Our theoretical analysis underpins the potential in using state-of-the-art spatial light modulation of nonresonant excitation beams to guide and focus polariton condensates away from their pumping region. The nonresonant excitation profile generates an excitonic reservoir that blueshifts the polariton mode and provides gain, which can be spatially tailored into lens shapes at the microscale to refract condensate waves. We propose several different avenues in controlling the condensate fluid, and demonstrate formation of highly enhanced and localized condensates away from the pumped reservoirs. This opens new perspectives in guiding quantum fluids of light and generating polariton condensates that are removed from detrimental reservoir dephasing effects.

Second-harmonic generation enhancement in high-contrast micropillar AlGaAs resonator in bound states in the continuum regime

It has been shown that the use of micropillar resonators, which comprise a cylindrical semiconductor cavity sandwiched between the Bragg mirrors can substantially increase the quality factor preserving the mode volume, and thus substantially enhance the local fields. Here, we show that these structures indeed can facilitate the significant enhancement of the SHG efficiency. We provide a specific design of the AlGaAs pillar microcavity and use the numerical modelling to directly show the resonant enhancement of the SHG efficiency. We believe that the presented results would be of high interest to the nanophotonic community, especially in nonlinear optics field.

Design of electrically driven single-photon source based on intra-cavity contacted microcavity with oxide-confined optical apertures emitting at 1.3 μm

We propose a hybrid microcavity design of a 1.3 μm range electrically driven single-photon source (SPS) consisting of two high-contrast dielectric distributed Bragg reflectors which surround a 3λ-thick semiconductor cavity with two intra-cavity contact layers and four 40-nm-thick oxide-confined apertures. According to 3D finite-difference time-domain modelling, the overall photon-extraction efficiency of ~74% and the Purcell factor of ~13 can be obtained by properly adjusting the position of oxide-confined apertures relative to the electric field of the fundamental optical mode. The studied SPS design also demonstrates a coupling efficiency of up to 13% within numerical aperture 0.12 in contrast to ~5% reached for a conventional semiconductor micropillar.

Observation of monochromatic and coherent luminescence from nanocavities of GaN nanowall network

Scaling-down the size of semiconductor cavity lasers and engineering their electromagnetic environment in the Purcell regime can bring about spectacular advance in nanodevices fabrication. We report here an unprecedented observation of a coherent Cathodoluminescence from GaN nanocavities (20–100 nm). Incident lower energy (< 15 kV) electron beams excite the band edge UV emission from the walls of the network whereas for higher energies, the emitted photons are spontaneously down converted into NIR and preferentially emerge from the nanocavities. Non-centrosymmetric structure of GaN and its nanowall geometry together facilitate this unique observation which is substantiated by our numerical results. At cryogenic temperatures, an intense and narrow laser-like NIR beam emanates out of the nanocavities. The work promises the possibility of fabrication of very high density (over 108/cm2) cavity lasers that are addressable by simple deflection and tuning of incident electron beams.

Fiber-based angular filtering for high-resolution Brillouin spectroscopy in the 20-300 GHz frequency range.

Brillouin spectroscopy emerges as a promising non-invasive tool for nanoscale imaging and sensing. One-dimensional semiconductor superlattice structures are eminently used for selectively enhancing the generation or detection of phonons at few GHz. While commercially available Brillouin spectrometers provide high-resolution spectra, they consist of complex experimental techniques and are not suitable for semiconductor cavities operating at a wide range of optical wavelengths. We develop a pragmatic experimental approach for conventional Brillouin spectroscopy that can integrate a widely tunable excitation-source. Our setup combines a fibered-based angular filtering and a spectral filtering based on a rotating single etalon and a double grating spectrometer for sequential reconstruction of Brillouin spectra. This configuration allows probing confined acoustic phonon modes in the 20-300 GHz frequency range with excellent laser rejection and high spectral resolution. Remarkably, our scheme based on the excitation and collection of the enhanced Brillouin scattering signals through the optical cavity allows for better angular filtering with decreasing phonon frequency. It can be implemented for the study of cavity optomechanics and stimulated Brillouin scattering over broadband optical and acoustic frequency ranges.

Frustules of Amphora sp. as a photonic crystal with photoluminescent CdS nanoparticles.

Diatom frustules have species-specific patterns of pores, striae, pores, and nanopores, periodically arranged on its silica surface, as sets of cavities that modify the vacuum electromagnetic density of states. Therefore, frustules may be considered photonic crystals; the interaction with light-emitting sources inside the pores may potentially result in enhancement or inhibition of their spontaneous radiative emission rate and frequencies. In this work, we studied the photoluminescence of cadmium sulfide nanoparticles (CdS-NP) deposited inside frustule cavities that conveyed evidence of cavity-NP interaction. We synthesized CdS-NP, a semiconductor compound achieving quantum dots small enough to impose confinement effects to the electronic states. CdS-NP and their clusters were physiosorbed onto the surface, striae, and predominantly inside the pores of the cleansed frustules of Amphora sp. A broad peak with a maximum intensity at 437 nm (2.84 eV) was recorded after excitation with a 375 nm light source, showing a large blue shift and signal amplification of the CdS-NP photoluminescence when these were embedded inside the pores of the silica frustule. Using the Brus equation, we estimated a NP size of 4.1 ± 0.2 nm for the CdS-NP snuggly packed inside the smaller pores of the frustule, of 10 ± 0.7 nm in average diameter, The emission Purcell enhancement factor for an emitting atom in a cavity was calculated. The obtained Q factor (c. 5) was smaller than typical Q factors for designed semiconductor cavities of similar dimensions, an expected situation if it is assumed that the pores are open-ended cavities.

Non-Hermitian tuned topological band gap

Externally controllable band gap properties of a material is crucial in designing optoelectronic devices with desirable properties on-demand. Here, a possibility of single parameter tuning of trivial to non-trivial topological band gap by the introduction of linear gain in an otherwise trivial insulator is investigated. Gain is selectively injected into a one dimensional lattice of dimers such that the resulting non-Hermitian Hamiltonian is symmetric under space-inversion but not under time-reversal. Inversion-symmetry of the lattice renders to probe the bulk-boundary correspondence and topological invariance by the bi-orthogonal Zak phase associated with a bulk Hamiltonian. Topological trivial to nontrivial phase transition and emergence of protected edge states are analytically shown to occur when the gain parameter is tuned across a non-Hermitian degeneracy. Tuneability of edge state location both at the boundary and inside the bulk by altering the gain distribution is discussed. Confirmation of gain-controlled topological edge state is reported in a realistic design of InGaAsP semiconductor cavity array.

Topological Insulator Laser Using Valley-Hall Photonic Crystals

Topological photonics has recently been proved a robust framework for manipulating light. Active topological photonic systems, in particular, enable richer fundamental physics by employing nonlinear light-matter interactions, thereby opening a new landscape for applications such as topological lasing. Here we report an all-dielectric topological insulator laser scheme based on semiconductor cavities formed by topologically distinct Kagome photonic crystals. The proposed planar semiconductor Kagome lattice allows broadband edge states below the light line due to photonic valley hall effect in telecommunication region, which provides a new route to retrieve nontrivial photonic topology and to develop integrated topological systems for robust light generation and transport.

Silicon-Au nanowire resonators for high-Q multiband near-infrared wave absorption

Semiconductors have been widely utilized to fabricate optoelectronic devices. Nevertheless, it is still a challenging task to achieve high-quality (Q) resonant light absorption using the high refractive index semiconductors. In this work, we propose a facile scheme for multi-band perfect absorption in the near-infrared range using an array of core–shell cylinder-shaped resonators which are composed of gold nanowires and thin silicon shells. Based on the cooperative effects between the photonic modes of the semiconductor cavity and the plasmonic resonances of the metal resonator, five sharp absorption peaks are observed with the maximal absorption close to 100% (99.98%) and a high Q factor up to 208. The multi-band sharp absorption is observed to be angle-insensitive and polarization-adjustable. Absorption efficiency can be quantitatively tuned via the polarization states following the classical Malus law. Moreover, different semiconductors such as gallium arsenide, indium arsenide, indium phosphide have been exploited to reproduce the sharp perfect absorption in this core–shell resonators platform. The remarkable features make the proposed system potential for multiple applications such as multispectral filtering, photo-detection and hot electron generation.

Hybrid InGaP nanobeam on silicon photonics for efficient four wave mixing

Abstract

Spectrally Selective Ultrathin Photodetectors Using Strong Interference in Nanocavity Design

Thinning the active layer’s thickness of the semiconductor down to a level comparable with the carriers’ diffusion length while keeping its absorption high is an ultimate goal to boost the performance of optoelectronic devices. Strong interference in multilayer structures is one of the promising and practical solutions owing to their simple and large-scale compatible fabrication route. These nanocavity designs not only provide near unity absorption, but they can also be designed in a way that a spectrally selective absorption response can be achieved. In this letter, we will demonstrate the functionality of a metal–insulator–semiconductor (MIS) cavity to obtain spectrally selective ultrathin photodetectors. To prove our theoretical and numerical findings, a 4-nm-thick amorphous silicon (a-Si)-based MIS cavity is designed, fabricated, and characterized. The experimental results show that the optimized cavity design can act as an efficient visible blind ultraviolet (UV) photodetector. The proposed design shows the responsivity values of 120 and 2.5 mA/W in the UV ( $\lambda =\textsf {350}$ nm) and visible ( $\lambda =\textsf {500}$ nm) regions, respectively.

Effects of variable thermal conductivity of a small semiconductor cavity through the fractional order heat-magneto-photothermal theory

In this investigation, a theoretical discussion of a fractional model of a heat order equation of a semiconductor medium in form of a spherical small cavity is studied. The model is taken as one dimensional under the effect of magnetic field and initial stress. The variable thermal conductivity is considered as a linear function of temperature (which depends on temperature). The medium has been studied in the context of photothermal transport processes (excited by light). The model presents the interaction between the waves of plasma (carrier density of free electric charge), namely the elastic and the thermal waves. The Laplace transform method is used to solve the main equations in cylindrical coordinates. The numerical technique (which depends on the Fourier series expansion) is used to get the complete solutions of the main variables under investigation. The thermal and mechanical loads such as the ramp heat type and free traction are applied to the inner surface of the cavity to obtain the main physical fields. The numerical computations of some main physical fields are discussed and plotted graphically.

Resonant-antiresonant coupled cavity VCSELs.

The wavelength tuning range of a tunable vertical-cavity surface-emitting laser (VCSEL) is strongly influenced by the design of the interface between the semiconductor cavity and the air cavity. A simplified model is used to investigate the origin of the dramatic differences in free spectral range (FSR) and tuning slope observed in semiconductor cavity dominant, extended cavity, and air cavity dominant VCSELs. The differences arise from the positioning of the resonant and antiresonant wavelengths of the semiconductor cavity with respect to the center wavelength. The air cavity dominant design is realized by designing an antiresonant semiconductor cavity, resulting in a larger tuning slope near the center of the tuning range and a wider FSR toward the edges of the tuning range. The findings from the simplified model are confirmed with the simulation of a full VCSEL structure. Using an air cavity dominant design, an electrically pumped laser with a tuning range of 68.38 nm centered at 1056.7 nm at a 550 kHz sweep rate is demonstrated with continuous wave emission at room temperature. This epitaxial design rule can be used to increase the tuning range of tunable VCSELs, making them more applicable in swept-source optical coherence tomography and frequency-modulated continuous-wave LIDAR systems.

Strong Exciton–Photon Coupling and Lasing Behavior in All-Inorganic CsPbBr3 Micro/Nanowire Fabry-Pérot Cavity

Macroscopic spontaneous coherence of exciton-polariton in semiconductor cavity is one important research field in condensed matter physics. All-inorganic micro/nanowire Fabry-P\'erot cavity with excellent optical performance makes it possible to realize strong coupling and lasing of exciton-photon at room temperature. In this work, we demonstrated strong coupling of exciton-photon and polariton lasing in CsPbBr3 micro/nanowires synthesized by CVD method. By exploring spatial resolved PL spectra of CsPbBr3 cavity, we observed mode volume dependent coupling strength , as well as significant increase in group index. Moreover, low threshold polariton lasing was achieved at room temperature within strong coupling regime; the polariton characteristic is confirmed by comparing lasing spectra with waveguided output spectra and the dramatically reduced lasing threshold. Our present results provide new avenues to achieve high coupling strengths potentially enabling application of exciting phenomena such as Bose-Einstein condensation of polaritons, efficient light-emitting diodes and lasers.

Unconventional photon blockade from bimodal driving and dissipations in coupled semiconductor microcavities

We propose an unconventional photon blockade scheme in coupled semiconductor microcavities embedded in a nonlinear Kerr medium in the presence of photon leakage and bimodal driving on two cavity modes, which consists of two spatially overlapping single-mode semiconductor cavities with cross-Kerr nonlinearity and two-photon tunneling. A detailed analysis is derived for the exact optimal conditions for strong photon antibunching with weak Kerr nonlinearities. It is very important to find the transition of the structures of the solution for the optimal detuning from the quartic equation to the cubic equation when changing the two complex driving fields appropriately. The transition originates from the second driving field that compensates the numbers of interference paths reaching a two-photon state. This unconventional photon blockade can be realized by coupled photonic crystal cavities filled with a nonlinear Kerr medium. This implies that nonlinear Kerr medium systems can be used to generate tunable single-photon sources by tuning the strength and relative phase of two complex driving fields under weak Kerr nonlinearity.