Showing papers on "Spontaneous emission published in 1995"
2,214 citations
TL;DR: In this paper, the authors review the family of optoelectronic devices whose performance is enhanced by placing the active device structure inside a Fabry-Perot resonantmicrocavity.
Abstract: We review the family of optoelectronic devices whose performance is enhanced by placing the active device structure inside a Fabry‐Perot resonantmicrocavity. Such resonantcavity enhanced (RCE) devices benefit from the wavelength selectivity and the large increase of the resonant optical field introduced by the cavity. The increased optical field allows RCE photodetector structures to be thinner and therefore faster, while simultaneously increasing the quantum efficiency at the resonant wavelengths. Off‐resonance wavelengths are rejected by the cavity making RCE photodetectors promising for low crosstalk wavelength division multiplexing(WDM) applications. RCE optical modulators require fewer quantum wells so are capable of reduced voltage operation. The spontaneous emission spectrum of RCE light emitting diodes(LED) is drastically altered, improving the spectral purity and directivity. RCE devices are also highly suitable for integrated detectors and emitters with applications as in optical logic and in communication networks. This review attempts an encyclopedic overview of RCE photonicdevices and systems. Considerable attention is devoted to the theoretical formulation and calculation of important RCE device parameters. Materials criteria are outlined and the suitability of common heteroepitaxial systems for RCE devices is examined. Arguments for the improved bandwidth in RCE detectors are presented intuitively, and results from advanced numerical simulations confirming the simple model are provided. An overview of experimental results on discrete RCE photodiodes, phototransistors, modulators, and LEDs is given. Work aimed at integrated RCE devices,optical logic and WDM systems is also covered. We conclude by speculating what remains to be accomplished to implement a practical RCE WDM system.
668 citations
TL;DR: In this article, the system of one or several quantum wells embedded in a planar semiconductor Fabry-Perot microcavity with distributed Bragg reflectors is studied in the framework of both a semiclassical and a full quantum theory.
451 citations
TL;DR: In this article, the theoretical framework needed for studying the dynamical behaviour of semiconductor laser exposed to three kinds of optical modulation is discussed, including the effect of monochromatic injection in terms of locking and non-locking dynamics, including a thermodynamic potential for phase jumps.
Abstract: In this review we discuss the theoretical framework needed for studying the dynamical behaviour of semiconductor lasers exposed to three kinds of optical modulation. We start by a derivation of the single-mode rate-equations for the slowly varying complex electric field and the inversion, and the necessary extensions for monochromatic optical injection and normal external optical feedback. The basic operating characteristics of the solitary semiconductor laser are analysed, including light-current curves and their dependence on the spontaneous emission level, as well as the optical spectrum. The effect of monochromatic injection is discussed in terms of locking and non-locking dynamics, including a thermodynamic potential for phase jumps. The basic ingredients for studying external optical feedback are given, including a derivation of the thermodynamic potential for phase-diffusion. After an introduction on optical phase conjugation, the field rate-equation for feedback from a phase-conjugate mirror is derived.
294 citations
TL;DR: In this paper, a GaSb quantum dot with a staggered band lineup (type II) is formed in a GaAs matrix using molecular beam epitaxy, where the dots are growing in a self-organized way on a GaAS(100) surface.
Abstract: Strained GaSb quantum dots having a staggered band lineup (type II) are formed in a GaAs matrix using molecular beam epitaxy. The dots are growing in a self‐organized way on a GaAs(100) surface upon deposition of 1.2 nm GaSb followed by a GaAs cap layer. Plan‐view transmission electron microscopy studies reveal well developed rectangular‐shaped GaSb islands with a lateral extension of ∼20 nm. Intense photoluminescence (PL) is observed at an energy lower than the GaSb wetting layer luminescence. This line is attributed to radiative recombination of 0D holes located in the GaSb dots and electrons located in the surrounding regions. The GaSb quantum dot PL dominates the spectrum up to high excitation densities and up to room temperature.
292 citations
TL;DR: The analysis describes the modification of the spontaneous emission rate as a function of refractive index, and serves to determine for the first time the radiative lifetime of Er in silicate glass, a parameter of great importance for Er-doped optical gain materials in telecommunication technology.
Abstract: Spontaneous emission is interpreted as a consequence of interaction between matter and electromagnetic radiation. Previous experiments, using for instance Rydberg atoms or semiconductor structures, have demonstrated that spontaneous emission can be influenced in cavities or near mirrors [1 ‐ 7]. In this Letter we will show an extremely simple way to modify the spontaneous emission rate, merely by bringing liquid films with certain refractive index in contact with a silica glass surface which is locally doped with luminescent Er 31 ions. Erbium shows clear photoluminescence (PL) around 1.54 mm [8], an important wavelength in optical telecommunication [9]. The theoretical description of spontaneous emission is usually based on concepts from quantum electrodynamics such as vacuum fluctuations and a creation and annihilation formalism. The inclusion of a dielectric interface requires special attention [10]. In this case, the variation in the spontaneous emission rate can be accounted for by the local classical density of states (DOS), which appears in Fermi’s golden rule. In this Letter, a straightforward calculation of the local DOS is performed, given the Fresnel equations for transmission and refraction at a dielectric interface. The analysis describes our data on the modification of the spontaneous emission rate as a function of refractive index, and serves to determine for the first time the radiative lifetime of Er in silicate glass, a parameter of great importance for Er-doped optical gain materials in telecommunication technology. Two samples of bulk sodalime silicate glass (refractive index n0 › 1.5) were implanted with 500 keV Er ions. Sample A was covered with a 120 nm thick Al film as a stopping layer, and sample B was uncovered during implantation. After implantation, the Al layer was etched off, and a thermal anneal at 512 ‐ C was performed. Erbium depth profiles for both samples, as determined using 2 MeV 4 He 1 Rutherford backscattering spectrometry (RBS), are shown in Fig. 1. The open data points for sample A show a profile peaked at the glass surface, with a half-width of 70 nm. The measured profile is a convolution of the detection resolution and the actual profile which is discontinuous at the surface. The drawn line shows the deconvoluted profile, which has a surface concentration of , 0.25 at. %. The solid data points in Fig. 1 show a Gaussian profile for sample B, centered at 150 nm depth from the surface, where the Er concentration is 0.17 at. %. The full width at half maximum is 100 nm. PL spectroscopy was carried out at room temperature. The 514.5 nm line of an Ar-ion laser was used to excite the Er, and the luminescence was spectrally analyzed with a monochromator and detected with a liquid-nitrogen cooled Ge detector. PL decay measurements were performed after exciting with a 1.5 ms pulse, using a digital averaging oscilloscope. Further details on sample preparation and PL measurements can be found in Ref. [11]. Various liquids, with refractive indices ranging from 1.3 to 1.7, and thickness in the order of a mm, were brought in contact with the sample surface on the front, while the luminescence signal was collected on the back side (see inset in Fig. 2).
226 citations
Abstract: The nature of guided modes and defect modes in periodic dielectric waveguides is investigated computationally for model systems in two dimensions. It is shown that defect states that exist within the band gap of guided modes can be excited to form tightly localized high-Q resonances.
221 citations
01 Jan 1995
TL;DR: The scientific fields of confined electrons and photons have become areas of major efforts worldwide as mentioned in this paper and their appeal originates in the many facets they offer in fundamental and applied science, in technology and device development, and to high technology, large-scale industries.
Abstract: The scientific fields of confined electrons and photons have become areas of major efforts worldwide. Their appeal originates in the many facets they offer in fundamental and applied science, in technology and device development, and to high technology, large-scale industries.
210 citations
TL;DR: In this article, it was shown that opal behaves as a semi-metallic photonic band gap material in the vicinity of photon energy 2.3 eV, which makes opal/semiconductor system a promising media for experimental studies of such PBG-related effects as inhibition of spontaneous emission, microcavity polariton, etc.
Abstract: The spectra of transmission and reflection of synthetic opal which has 3-dimensional periodic structure were measured at different orientations of incident beam relative to the sample facets. It is shown that opal behaves as «semi-metallic» photonic band gap (PBG) material in the vicinity of photon energy 2.3 eV. The synthesis of CdS microcrystals embedded in the pores of opal was made for the first time in an attempt to form a system of quantum dots. Optical spectra (reflection and transmission, photoluminescence and Raman scattering) were studied. The results demonstrate good crystallinity of microcrystals embedded in opal matrix and exhibit well-pronounced quantum confinement effects in fundamental edge absorption spectra. The spectral overlap of the PBG of opal with electronic band gap of many of II–VI semiconductors seems to make opal/semiconductor system a promising media for experimental studies of such PBG-related effects as inhibition of spontaneous emission, microcavity polariton, etc.
204 citations
Book•
01 Jan 1995
TL;DR: In this paper, the authors proposed a method to control spontaneous emission in Semiconductor microcavities using a combination of the KKR method and the Intersubband Transitions in Quantum Wells.
Abstract: Confined Electrons and Photons: A Summary:.- Basic Solid State Optics in Bulk and 2D Structures.- Dynamics of Optical Excitations in Semiconductors.- Optical Transitions, Excitons and Polaritons in Bulk and Low-Dimensional Semiconductor Structures.- Electron States in Biased Heterostructures.- Phonons and Electron-Phonon Interaction in Low-Dimensional Structures.- Excitonic Radiative Dynamics in Semiconductor Quantum Wells.- Superlattices and Quantum Wells in Organic Semiconductors: Excitons and Optical Non-linearities.- Intersubband Transitions in Quantum Wells.- Confined Electrons in 1D and 0D.- Principles of Electron Solid State Electron Optics.- Atomic-like Spectroscopy of Low Dimensional Electron Systems.- Inelastic Scattering and Thermalization in low-III-V Semiconductor Structures.- Synthesis and Spectroscopy of II-VI Quantum Dots: an Overview.- Prospects of High Efficiency Quantum Boxes obtained by direct epitaxial growth.- Confined Photons.- Atoms in Cavities.- Controlling Spontaneous Emission and Optical Microcavities.- Spontaneous Emission Control in Semiconductor Microcavities.- Strong Coupling in Semiconductor Microcavities.- Localization of Light in Disordered and Periodic Dielectrics.- Photonic Bloch Waves and Photonic Band Gaps.- Light Emission in Photonic Crystal Micro-Cavities.- Special Topics - Applications.- Semiconductor Nanostructure lasers: Fundamentals and Fabrications.- Quantum Wells Optical Switching Devices.- High-efficiency, Narrow Spectrum Resonant Cavity Light Emitting Diodes.- Short Papers (Seminars and Selected Posters).- Spontaneous Emission Control in Planar Structures: Er3+ in Si/SO2 Microcavities.- Vacuum Rabi Splitting in a Semiconductor Microcavity.- Impurity Modes in One-Dimensional Periodic Systems: The Transition from Photonic Bandgaps to Microcavities.- Photonic Bandgap Calculations: Inward and Outward Integral Equations and the KKR method.- Soliton-Polariton Interaction near an Excitonic Resonance in Semiconductors.- Dynamics of Excitons and Electron-Hole Plasma Confined in Semiconductor Nanocrystals.- Coupled-Quantum Wells for Optical Modulation.- In-plane Electro-Optic Effect in a Quantum Well.- Reprinted Papers: Basics.- Aspects of Polaritons.- Interband Optical Transitions in Extremely Anisotropic Semiconductors.- Effect of Retarded Interaction on the Exciton Spectrum in One-Dimensional and Two-Dimensional Crystals.- On the Exciton Luminescence at Low temperatures: Importance of the Polariton Viewpoint.- Spatial and Spectral Features of Polariton Fluorescence.- Reprinted Papers: Confined Electrons.- Studies of Exciton Localization in Quantum-Well Structures by Nonlinear-Optical Techniques.- Excitonic Optical Nonlinearity and Exciton Dynamics in Semiconductor Quantum Dots.- Very Large Optical Nonlinearity of Semiconductor Microcrystallites.- Reprinted Papers: Confined Photons.- Spontaneous Emission Probabilities at Radiofrequencies.- Inhibited Spontaneous Emission.- Inhibited Spontaneous Emission in Solid State Physics and Electronics.- Cavity Q.E.D.- Cavity Quantum Electrodynamics at Optical Frequencies.- Physics and Device Applications of Optical Microcavities.- Optical Processes in Microcavities.- Photon Number Squeezed States in Semiconductor Lasers.- Photonic Bandgap Structures.- Applications of Photonic Band gap Structures.- Contributors.
202 citations
Book•
30 Oct 1995
TL;DR: Weisbuch et al. as discussed by the authors presented a simple theory on the effect of Dephasing of Vacuum Fields on Spontaneous Emission in a Microcavity, Y. Yamamoto.
Abstract: Spontaneous Emission in Optical Cavities: A Tutorial Review, E.V. Goldstein and P. Meystre Introduction Free Space Spontaneous Emission Spontaneous Emission in Cavities Velocity-Dependent Spontaneous Emission Conclusion A Simple Theory on the Effect of Dephasing of Vacuum Fields on Spontaneous Emission in a Microcavity, Y. Lee Introduction Theoretical Model I Theoretical Model II Summary Appendicies A-C Effects of Atomic Broadening on Spontaneous Emission in an Optical Microcavity, K. Ujihara Introduction Analysis of Spontaneous Emission Discussion and Conclusion Microcavities and Semiconductors: The Strong-Coupling Regime, C. Weisbuch, R. Houdre, and R.P. Stanley Introduction The Fabry-Perot Resonator: A Planar Microcavity Models of Strong Light-Matter Coupling Optics of Semiconductors Conclusion Electromagnetic Field Mode Density Calculated via Mode Counting, S.D. Brorson Introduction No Confinement: A Dipole in Free Space One Dimension of Confinement: The Planar Mirror Cavity Two Dimensions of Confinement: The Waveguide Cavity Three Dimensions of Confinement: The Box Microcavity Discussion Spontaneous Emission in Dielectric Planar Microcavities, G. Bjork and Y. Yamamoto Introduction The Ideal Planar Cavity Fundamentals of Dielectric Bragg Mirrors Dielectric Cavity Spontaneous Emission Pattern Dielectric Cavity Spontaneous Emission Lifetime Dielectric Cavity Stimulated Emission Conclusions and Outlooks Spontaneous Emission in Microcavity Surface Emitting Lasers, T. Baba and K. Iga Introduction Spontaneous Emission in a Microcavity Expression of Radiation Energy Modes in Microcavity SELS Spontaneous Emission Factor Effects of Electron Quantum Confinement Lasing Characteristics Summary Spontaneous and Stimulated Emission in the Microcavity Laser, H. Yokoyama Introduction Photon Emission in Microcavities Microcavity Lasers Microcavity Semiconductor Lasers Prospects for Device Applications Summary Recent Progress in Optical Microcavity Experiments, H. Yokoyama Introduction Cavity Configurations Alterations in Spontaneous Emission Properties Laser Oscillation Summary Application of Microcavities: New Photoelectronic Integrated Systems, I. Hayashi Introduction Photoelectronic Integrated Systems Micro-Photoelectronic Devices Summary and Future Prospects Index
Proceedings Article•
22 May 1995
TL;DR: Cathodoluminescence was used to directly image the spatial distribution of the quantum dots by mapping their luminescence and to spectrally resolve very sharp peaks from small groups of dots, thus providing experimental verification for the discrete density of states in a zero-dimensional quantum structure.
Abstract: Ensembles of defect-free InAIAs islands of ultrasmall dimensions embedded in AIGaAs have been grown by molecular beam epitaxy. Cathodoluminescence was used to directly image the spatial distribution of the quantum dots by mapping their luminescence and to spectrally resolve very sharp peaks from small groups of dots, thus providing experimental verification for the discrete density of states in a zero-dimensional quantum structure. Visible luminescence is produced by different nominal compositions of In x AI( 1– x ) As-AI y Ga (1– y ) As.
TL;DR: Quantum interference between decay processes from two upper levels, which are coupled by the same vacuum modes to a lower level, have been investigated and its effects on the spontaneous emission spectrum have been studied.
Abstract: Quantum interference between decay processes from two upper levels, which are coupled by the same vacuum modes to a lower level, have been investigated and its effects on the spontaneous emission spectrum have been studied. The interference can result in spectral narrowing and a black dark line in the spectrum. The population in the upper levels is not a simple exponential decay due to the interference.
TL;DR: In this paper, a compact and transparent plane-wave expansion of the complete Green function for an absorbing multilayered system is derived and the cross sections derived, besides generally describing light scattering on molecules embedded in a multilayer, correctly reproduce the effects of field confinement on light scattering in a planar cavity as predicted recently by the quantum-mechanical theory of Cairo et al.
Abstract: A compact and transparent plane-wave expansion of the complete Green function for an absorbing multilayered system is derived. The plane-wave solutions involved match, in the appropriate limit, the space-mode functions recently employed for quantization of the radiation field in a planar cavity and make this Green function particularly convenient for consideration of optical processes in realistic cavities and multilayers in general. This is illustrated by considering classically light scattering on a molecule in a planar cavity. It is demonstrated that the cross sections derived, besides generally describing light scattering on molecules embedded in a multilayer, correctly reproduce the effects of field confinement on light scattering in a planar cavity as predicted recently by the quantum-mechanical theory of Cairo et al. [Phys. Rev. Lett. 70, 1413 (1993)]. It is also pointed out that scattering into waves guided by the cavity lossy (metallic) mirrors may become an effective process in low-order microcavities. As a by product, a classical approach to spontaneous emission in absorbing planar cavities emerges from these considerations.
TL;DR: In this paper, a complete model with the spin-orbit coupling for strained quantum-well lasers is presented, and explicit formulas for the momentum-matrix elements are given, and the improvement in the threshold current density of tensile strained quantum well lasers, as compared with that of the unstrained quantum well, is shown to result from the enhanced momentum matrix.
Abstract: A complete model with the spin-orbit coupling for strained quantum-well lasers is presented. Explicit formulas for the momentum-matrix elements are given. The improvement in the threshold current density of tensile strained quantum-well lasers, as compared with that of the unstrained quantum well, is shown to result from the enhanced momentum matrix. The differential gain and the linewidth enhancement factor are calculated. The theoretical results show a smaller linewidth enhancement factor for compressively and tensile strained quantum wells than that of the unstrained structure, as has been experimentally observed. The temperature behavior of both the radiative component and the Anger component of the threshold current density is shown. Due to a decrease of gain and differential gain with increasing temperature, the threshold carrier density in unstrained quantum wells is increased with a large increment of the Auger recombination current at high temperature. For strained quantum wells, this increment is moderate because of the smaller threshold carrier density. >
TL;DR: In this article, a systematic map of the various instabilities induced in a semiconductor laser subject to strong optical injection as the amount of optical injection power and frequency detuning is varied is presented.
Abstract: We have experimentally obtained and theoretically analyzed a systematic map of the various instabilities induced in a semiconductor laser subject to strong optical injection as the amount of optical injection power and frequency detuning is varied. Two distinct islands of chaos have been identified in the injection‐locked region. They are separated by regions of period one and period two solutions. Spontaneous emission noise obscures the observation of high periodic orbits.
TL;DR: In this paper, a large signal dynamic computer model was used to compare the performance of CPM and self-colliding pulse mode-locking (SCPM) in semiconductor laser devices.
Abstract: Monolithic colliding pulse mode-locking (CPM) in semiconductor lasers is compared with self colliding pulse mode-locking (SCPM) through a large signal dynamic computer model which incorporates most of the significant features of semiconductor lasers. These include gain saturation, spontaneous emission, the gain-frequency relation, and the line-width enhancement factor. This new model replicates many of the published experimental results and also gives additional insight into the internal operation of the device. In particular, gain saturation combined with the standing waves created by colliding pulses within the saturable absorber produce a transient gain grating. This is found to have significant effects in locking either the even or the odd modes together in CPM. A performance comparison between CPM and SCPM is completed and some key design parameters of both configurations are explored. >
TL;DR: In this paper, the authors demonstrate the preparation of narrow-band porous-silicon reflectors integrated on porous silicon layers by electrochemical etching, and they have obtained both a narrowing and enhancement of the emission line, and a highly concentrated radiation pattern.
Abstract: We demonstrate the preparation of narrow‐band porous‐silicon reflectors integrated on porous‐silicon layers by electrochemical etching. By carefully tuning the resulting photon cavity mode around the maximum of the porous silicon photoluminescence, we have obtained both a narrowing and enhancement of the emission line, and a highly concentrated radiation pattern. These results show that the porous silicon spontaneous emission is modified because of the coupling with the photon cavity mode.
TL;DR: A laser system that generates multiterrawatt transform-limited pulses, with good beam quality and low amplified-spontaneous-emission levels, at a duration near the theoretical limit imposed by gain narrowing in Ti:sapphire is reported.
Abstract: We report the generation of 26-fs-duration pulses, with an energy of 60 mJ, from a simple multipass Ti:sapphire amplifier system. The peak power of our amplified pulses is 2 TW, and the repetition rate is 10 Hz. Our amplifier design consists of two highly doped multipass amplifiers and is simple and compact. We use an all-reflective, low-groove-density grating stretcher and compressor, combined with a relatively short material path length in the amplifier. This design allows us to minimize higher-order dispersion. The result is a laser system that generates multiterrawatt transform-limited pulses, with good beam quality and low amplified-spontaneous-emission levels, at a duration near the theoretical limit imposed by gain narrowing in Ti:sapphire.
TL;DR: In this paper, the authors reviewed the current status of a photon scanning tunneling microscope (PSTM) and its application and proposed a virtual photon based on an intuitive modeling of the localized evanescent light.
Abstract: The present status of a photon scanning tunneling microscope (PSTM) and its application are reviewed. In order to realize a nanometric apertured fiber probe, a highly reproducible chemical etching process was developed to realize a sharpened fiber with the cone angle and tip diameter as small as 14/spl deg/ and 3 nm, respectively. The possibility of tailoring the shapes of the sharpened fibers was presented. Chemical etching and nanometric photolithography were developed to fabricate a metallic aperture with a diameter of 30 nm (or even smaller) on the sharpened fiber tip. Imaging experiments with biological specimens were carried out by operating the PSTM in the collection mode and illumination mode geometries. Dependencies of these images on the polarization state of the incident light were found, and a resolution of 10 nm or even smaller was achieved. Nondestructive inspection of dielectric optical waveguides with subwavelength resolution was proposed by presenting the diagnosed results of a proton-exchanged LiTaO/sub 3/ waveguide. Possibilities of diagnosing nanometric active photonic devices were also demonstrated through imaging experiments of semiconductor quantum dots. Experiments on fluorescence detection from dye-doped nanometric polystyrene spheres confirmed the enhanced efficiency of coupling of the fluorescence to the fiber tip, and this was attributed to the spatially inhomogeneous spontaneous emission due to the short-range electromagnetic interaction between the sphere and probe tip. To demonstrate the possibilities of nanometric fabrication, high density optical storage, especially the photon-mode storage, was demonstrated to realize a stored circular pit of 100 nm diameter on an organic thin film. As an ultimate goal of fabrication to explore the future technology of atomic-level material processing, an atom guide using a hollow fiber and atom trapping by the illumination mode PSTM were proposed to control the thermal motion of freely dying atoms in vacuum. The concept of a virtual photon based on an intuitive modeling of the localized evanescent light was introduced to provide a semiclassical theory of the PSTM. Transfer functions of the PSTM were calculated by using this model, which agreed qualitatively with the experimental results. >
TL;DR: Nanometer-scale quantum dots are fabricated using the Stranski-Krastanov growth mode of InAs on GaAs(001) for an average coverage of four monolayers, 10 11 cm -2 pyramidal-shaped dots (12±1 nm base along, 5± 1 nm high) are formed as observed in plane-view and cross-section transmission electron microscopy as mentioned in this paper.
Abstract: Nanometer-scale quantum dots are fabricated using the Stranski-Krastanov growth mode of InAs on GaAs(001) For an average coverage of four monolayers, 10 11 cm -2 pyramidal-shaped dots (12±1 nm base along , 5±1 nm high) are formed as observed in plane-view and cross-section transmission electron microscopy The quantum dots exhibit short-range order, aligning along rows in directions The three-dimensional confinement of the wave function results in ultrasharp luminescence lines (full width at half maximum <015 meV) from individual dots as revealed with highly spatially resolved cathodoluminescence Even at elevated temperatures extremely sharp lines are observed, proving the δ-like zero-dimensional electronic density of states
TL;DR: In this article, the authors measured the refractive index dependence of the spontaneous emission rate of electric and magnetic dipole transitions in dielectrics and showed that local field effects are clearly observed in the electric dipole results and discrimination between different theoretical descriptions is made.
Abstract: We report measurements of the refractive index dependence of the spontaneous emission rate of electric and magnetic dipole transitions in dielectrics. Local field effects are clearly observed in the electric dipole results and discrimination between different theoretical descriptions is made. The magnetic dipole results are well described by quantum electrodynamical considerations without local field effects.
TL;DR: In this paper, the photoluminescence of GaN layers grown on 6H-SiC substrates was studied in the temperature range 77-900 K and the temperature dependence of the band gap was measured throughout the entire temperature range.
Abstract: Photoluminescence of GaN layers grown on 6H–SiC substrates was studied in the temperature range 77–900 K. GaN layers were grown by metalorganic chemical vapor deposition. The temperature dependence of the band gap of GaN was measured throughout the entire temperature range. Edge cavity stimulated emission from photopumped GaN layers was observed in the temperature range 77–450 K. The full width at half‐maximum (FWHM) of the stimulated emission peak was ∼3 nm at 300 K and ∼7 nm at 450 K. Multipass stimulated emission with Fabry–Perot modes was detected from GaN. The FWHM of Fabry–Perot modes was ∼0.2 nm (300 K).
TL;DR: In this article, the authors developed a classical theory for the calculation of the emission power from the electric dipole located in three-dimensional photonic crystals by incorporating the plane-wave method, dyadic Green's function, Poynting theorem, and tetrahedron k-space integration.
Abstract: It has been suggested that spontaneous emission can be inhibited if atomic transition frequencies fall inside photonic band gaps, that is, three-dimensional frequency stop bands of electromagnetic waves generated by three-dimensional periodic dielectric materials (photonic crystals). There has been a growing interest in how atomic emission spectra are changed quantitatively inside the photonic crystals. We develop a classical theory for the calculation of the emission power from the electric dipole located in three-dimensional photonic crystals by incorporating the plane-wave method, dyadic Green’s function, Poynting theorem, and tetrahedron k-space integration. With the method we perform numerical computations for the emission power of an electric dipole located in the photonic crystals of the fcc lattice structure with spherical atoms. The results show the total inhibition of emission in the photonic band gap as well as strong enhancement around the band edges. In addition, the data indicate the strong dependencies of the emission spectrum on the dipole position and the dipole moment in the photonic crystal.
TL;DR: In this paper, the design and optical properties of a spincoated multilayer organic microcavity are reported, and the spontaneous emission rate is increased in the cavity by means of time resolved luminescence spectroscopy.
Abstract: We report on the design and the optical properties of a spin‐coated multilayer organic microcavity. Tri(stilbene)amine blended with polysulfone as the first layer and an oxadiazole derivative (BPBD) blended with polystyrene as the second layer are sandwiched between two planar mirrors. Enhancement of the luminescence and spectrally narrow emission are observed. By means of time resolved luminescence spectroscopy we show that the spontaneous emission rate is increased in the cavity.
Patent•
29 Dec 1995TL;DR: In this article, an electroluminescent structure and a method of fabrication of that structure in materials which have an indirect bandgap in their bulk form are presented, and the processing steps can all be standard VLSI methods.
Abstract: The present invention consists of an electroluminescent structure and method of fabrication of that structure in materials which have an indirect bandgap in their bulk form. The processing steps can all be standard VLSI methods. Quantum columns, quantum wires or quantum dots may be formed, for example in an array, by masking, reactive ion etching and oxidation. When the semiconductor core is sufficiently thin, quantum mechanical confinement effects raise the energy and the radiative recombination efficiency of injected carriers. Tuning the core diameters allows selection of individual or multiple wavelength emission bands.