Showing papers on "Optical microcavity published in 1995"

Spontaneous Emission and Laser Oscillation in Microcavities

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

Article comprising a microcavity light source

Abstract: Optical microcavities are potentially useful as light emitters for, eg, flat panel displays Such microcavities comprise a layer structure, including two spaced apart reflectors that define the cavity, with a layer of organic (electroluminescent) material disposed between the reflectors We have discovered that a microcavity can simultaneously emit radiation of two or more predetermined colors such that the emission has a desired apparent color, exemplarily white Emission of two or more colors requires that the effective optical length of the cavity is selected such that the cavity is a multimode cavity, with the wavelengths of two or more of the standing wave modes that are supported by the cavity lying within the emission region of the electroluminescence spectrum of the active material

Raman Scattering Enhancement by Optical Confinement in a Semiconductor Planar Microcavity

Abstract: We report optical-phonon Raman scattering enhancements of over 4 orders of magnitude in a $\frac{\ensuremath{\lambda}}{2}$ semiconductor planar microcavity. By varying the incidence angle both excitation and Stokes photons can simultaneously resonate with the cavity mode, their fields being strongly amplified. We demonstrate the cavity geometry as a promising tool to study solid state excitations in reduced dimensions with highly increased sensitivity.

Microcavity effects in a spin‐coated polymer two‐layer system

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.

From Fermi's Golden Rule to the Vacuum Rabi Splitting: Magnetopolaritons in a Semiconductor Optical Microcavity

Abstract: We show that magnetic quantization of the carrier free motion into discrete Landau levels for quantum wells inserted in a Fabry-P\'erot microcavity allows continuous tuning of the electromagnetic interaction from the weak coupling regime (irreversible regime described by Fermi's golden rule) to the strong coupling regime (where coherent time dependence and the vacuum Rabi splitting prevail).

Very-low-threshold index-confined planar microcavity lasers

Abstract: A fabrication process for laterally index-confined planar microcavity lasers is given that results in continuous-wave thresholds as low as 59 /spl mu/A for a properly tuned cavity (T=250 K). Characterization of the spontaneous emission mode shows that the lateral confinement, when reduced to the mode size expected for the planar cavity, appears to increase the spontaneous emission coupling to the lasing mode. >

16% external quantum efficiency from planar microcavity LEDs at 940nm by precise matching of cavity wavelength

Abstract: High efficiency substrate emitting microcavity InGaAs/(Al)GaAs 3 QW LEDs are reported. The use of regrowth for cavity resonance tuning and its effect on device performance, are demonstrated. The best results obtained include external quantum efficiencies of 16%. At 5 mA, 1 mW of optical power is delivered with an intensity of 280 µW/sr.

Observation of dressed‐exciton oscillating emission over a wide wavelength range in a semiconductor microcavity

Abstract: We have observed the dressed‐exciton oscillating emission in the time domain and the associated spectral splitting in the frequency domain from a GaAs single quantum well microcavity over a very broad range of cavity resonant wavelengths. The spectral splitting and temporal oscillation period have been measured to be nearly constant over two orders of magnitude variation of pump intensity, which confirms the linear bosonic feature of Wannier excitons in the weak excitation regime.

Transient Pulse Response of In0.2Ga0.8As/GaAs Microcavity Lasers

Abstract: We investigate the transient emission of two In0.2Ga0.8As/GaAs microcavity laser samples with one and three quantum wells at 20 K following femtosecond optical excitation. The stimulated emission time is faster when the cavity resonance is tuned to shorter wavelengths within the gain spectrum of the quantum well. A larger number of quantum wells makes the dynamical response faster also. The narrowest pulse width observed is 6.8 ps, and the shortest rise time is 1 ps.

Spontaneous emission in microcavities with distributed mirrors

Abstract: This paper presents an analytic approach to spontaneous emission in resonators with distributed Bragg reflectors (DBR's). The foundation of our analysis is the hard mirror (or penetration depth) approximation. Which we extend to radiation with both angular and frequency distributions. This has allowed us to derive approximate analytic expressions for the divergence angle of the spontaneous emission, the spontaneous emission rate and the spontaneous emission coupling factor in planar DBR resonators. These analytic tools provide insight into the considerable limitations to controlling spontaneous emission with DBR boundaries. We also explore cavity controlled spontaneous emission with the classical tools of intracavity field profiles, the induced EMF method and millimeter wave experiments-all of which are applied to distributed mirror boundaries. >

Efficient Phase Conjugation Wave Generation from a GaAs Single Quantum Well in a Microcavity

Abstract: We propose a scheme of efficient phase conjugation wave generation with a semiconductor microcavity. We show experimental results for a GaAs single quantum well (SQW) in a planar AlGaAs microcavity at 13 K. A single pump beam directed normally to the planar cavity produces counterpropagating pump fields in the QW region. Using the quantum confined Stark effect, we tune the exciton resonance energy around the fixed cavity resonance. Large enhancement of the signal occurs when the exciton resonance coincides with the cavity resonance.

Microcavity vacuum-field configuration and spontaneous-emission power

Abstract: Vacuum-electromagnetic-field modes in microcavities are redistributed and renormalized, and hence the pattern and the rates of the spontaneous emission are modified. Consequently, the conventional technique for calculating cavity spontaneous- emission power based on the scalar (isotropic) energy mode density formalism is not applicable to vertical-cavity lasers (VCLs). A comprehensive model for spontaneous emission from three-dimensional dielectric microcavities is dearly needed. Such a model must account for radiation intensity along both axial and lateral emission directions. The utility of such a model is greatly enhanced if it is primarily analytical in its formalism and can quantitatively predict the measured intensities. This paper presents the development of the above prescribed model and compares its predictions to the experimental data from air-post index-guided VCLs, for which both axial and lateral spontaneous-emission intensities can be readily measured.

Double quantum well in a semiconductor microcavity: Three-oscillator model and ultrafast radiative decay.

Abstract: A complete study of excitons in double quantum wells embedded in a semiconductor microcavity is presented In the strong coupling regime we predict the possibility of observing three peaks in optical spectra when the two quantum well excitons have different resonance energies, and discuss the best structure parameters for observing this phenomenon In the weak coupling regime we show that a radiative lifetime as short as \ensuremath{\approxeq}100 fs can be obtained by taking advantage of the coherence between the wells in addition to the microcavity effect This ultrashort radiative lifetime is shown to be observable even in the presence of disorder

Steady-state and transient characteristics of microcavity surface-emitting lasers with compressively strained quantum-well active regions

Abstract: In conventional semiconductor lasers, the dimensions of the optical cavity greatly exceed the photon wavelength, and the photon density of states forms a continuum since it is essentially that of a bulk system. On the other hand, in an ideal laser, one would like to have a single optical mode coincident with the maximum in the gain spectrum of the active medium. We show that substantial density-of-states quantization and enhancement of the fraction of photons spontaneously emitted into the lasing mode can be obtained by reducing the lateral width of the surface-emitting laser. For emission at /spl lambda/=0.954 /spl mu/m, the threshold current density can be drastically reduced by increasing the coupling factor to a few percent. For a cavity structure width of 0.3 /spl mu/m, the threshold current density is 50 A/cm/sup 2/, compared with 250 A/cm/sup 2/ for the 0.6-/spl mu/m cavity. At lower still lateral widths, the cavity loses its vertical character, and confinement of the lateral optical mode rapidly deteriorates. The large-signal response of microcavity lasers is slightly improved primarily due to elimination of mode competition in intrinsically single-mode microcavities, with relaxation times close to 1 ns. The enhancement of the spontaneous emission coupling factor results in an increase of the relaxation oscillation frequency and improvement in the standard small-signal response of microcavity lasers. For J=10J/sub th/, the -3 dB modulation frequency exceeds 40 GHz. Since low threshold current densities may be achieved in microcavity lasers, the gains in small-signal performance are primarily extrinsic, i.e., higher modulation bandwidths ace accessible for the same injection. >

Confined Electrons and Photons: A Summary

Abstract: The 1993 Erice Advanced Study Institute (ASI) on Confined Electrons and Photons was organized along two main lines: one is the increasing electron-motion quantization occuring when semiconductor heterostructures are progressively structured in 1, 2, 3 directions (quantum wells, wires or boxes respectively), the other is the photon mode control obtained by structuring the dielectric function of a material system, leading to optical microcavity or photonic bandgap effects.

Characteristics of Organic Photo- and Electro-Luminescent Devices with Double Mirrors

Abstract: The luminescent characteristics of organic thin films sandwiched between two mirrors were measured. The optical length between the two mirrors was set according to the scale of the luminescent wavelength in order to compose a microcavity structure. Photoluminescence (PL) and electroluminescence (EL) from tris(8-hydroxyquinoline)aluminum (ALQ) were enhanced at distinct resonating wavelengths, and suppressed in other regions. Then, narrow and enhanced luminescent peaks were observed from the devices with the microcavity structure. Based on their injection current dependence, the primary cause of these spectra was speculated to be spontaneous emission. An EL sample with the microcavity structure for multicolor emissions was fabricated.

Controlling Spontaneous Emission and Optical Microcavities

Abstract: The main subject of this article is to describe some possible prescriptions for realizing optical microcavity devices. Optical microcavities are resonators that have at least one dimension on the order of a single optical wavelength. In these structures, materials’ light emission properties are greatly altered compared to those in such large sized cavities as used for conventional laser oscillators. Thus, even though we are not much concerned with advanced quantum electrodynamics in the cavity, understanding essential physics of light emission in microcavity is really important. Here, simplified discussions are mainly developed within the framework of Fermi golden rule, from the device design application point of view. We put stress on basics of the controlling spontaneous emission and the laser oscillation of optical microcavities rather than on material physics aspects of semiconductor lasers. We will see that the essential point for realizing ultralow power consumption light emitting devices are very simple, simultaneously, there are some practical problems to be solved for high performance devices.

Transverse quantum correlations, stimulated emission and Einstein causality in the active optical microcavity

Abstract: An extended theoretical and experimental analysis is reported of the classic problem, first discussed by E Fermi, of the interaction between two quantum systems A and B. In our case, the two systems are confined within an optical microcavity and the interaction takes place in the transverse direction, i.e. orthogonal to the only k-wavevector allowed by the cavity with the minimum spacing d= 1/2 lambda 0. In these conditions, our theory analyses in detail the process of two-atom super-radiance. The experiment consists of an investigation, by the use of a femtosecond laser, of the process of coupling of two microlasers active over the same transverse mode of an optical microcavity.

Investigations on multicolor display by organic luminescent devices with optical microcavity structure

Abstract: The emitted light of an organic electroluminescent (EL) device has a narrow half-width in its spectrum and its intensity is high if a semitransparent mirror is placed on the light-emitting side and the optical distance between the mirror and a metal electrode is set on the order of the emitting wavelength. This phenomenon is believed to be due to microcavity formation. This paper shows that device characteristics can be explained qualitatively by equations derived from the propagations. It is also shown that it is possible to obtain different colors from the same device material using this characteristic. The basic device structure for multicolor display will be shown. The dependence of luminescence on the detecting angle is theoretically and experimentally confirmed, and it is concluded that the device can be used for display applications.

An all-optical signal discrimination experiment using a high-speed saturable absorberoptical gate

Abstract: Figures 2(a) and (b) show calculated CR-limited switching times as a function of APin for various FET amplifying stage numbers (n). The parameters used in the calculations are listed in Table 1. From the figures, the usefulness of using multistage FET amplification for high speed operation is apparent. For the modulator, the switching time is reduced by supplying large APin. While in the VCSEL case, when the bias current is set above the threshold current to avoid lasing delay time, the switching time, except for the

Optical, optoelectronic or photonic element with at least one laterally confined optical cavity and its method of fabrication

Abstract: The optical, opto-electronic or photonic component comprises an optical cavity (2a), for a given wavelength (L), which is defined between two reflectors (3,4). The cavity is also confined laterally. The reflectors are of the type which change the phase of the reflected wave. The region (2b) which laterally surrounds the cavity and the cavity itself is made of the same material. The region between the reflectors which corresponds to the optical cavity presents a cut-off wavelength which is greater than the cut-off wavelength of the surrounding region. The operating wavelength of the cavity lies between the two cut-off wavelengths. The optical thickness of the cavity region is greater than the optical thickness of the surrounding region.

Near-field optical properties of CaAs quantum dot structures measured by photon scanning tunnelling

Abstract: Yasunori Toda, Motonobu Kourogi,* Yasushi Nagamme:* Yasuhiko Arakawa,** Motoichi Ohtsu,' Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Teclmology, 4259 Nagatsuda, Midori-ku, Yokohama, Kanagawa 227, Japan Nowadays requirements of study of photonic devices, i.e., superlattice, nanoclustar, etc. are generally met by optical measurements of conventional far-field technique. However, optical studies of these structures beyond the sub-wavelength resolution have already been a subject of near-field optics. Recently, a photon scanning tunnelling microscope (P-STM) has become a powerful and indispensable tool for providing the information on opticai propeities with FA2 Fig. 1. Schematic drawing of the fractional-layer superlattice quantum wire sub-wavelength resolution. Elasic princi(FLS-Q~~R) array structure. "

Simple technique for two-photon absorption measurements in polymeric waveguide channels

Abstract: A simple technique for two-photon absorption measurements by pulse shape deformation in channel optical waveguides is described. Measurements on a ps time scale are performed. Results are in good agreement with literature values.

Comparative study of pulsed and cw injection seeding for spectral-narrowing of a Ti:sapphire laser

Abstract: Various widely-tunable solid-state lasers and optical parametric oscillators have been developed. In these lasers, however, the tuning region is limited by the bandwidth of coatings rather than the potential tuning region of the material itself. For example, typically four mirror sets must be changed for the entire tuning of cw Tisapphire lasers. The breakthrough in the coating technology has been required. In this presentation, we will describe tuning of a Ti:sapphire laser over the entire range using a single set of newly developed optics. The high reflection coatings for lowloss, broad-band mirrors consist of electron beam deposited Taz0,/Si02 multilayers on fused silica substrates. The coatings consist of 10 stacks and each stack has 6 to 12 layers (99 layers in total). Optical losses of 500 to 1500 ppm (R = 99.85 to 99.95%) were attributed mainly to optical scattering in the 680 to 1060 nm region, which completely covers the Ti:sapphire laser gain curve (Fig. 1). This loss level is as low as that of narrow-band mirrors. In addition, no degradation was observed at 500 kW/cm2 for an Ar laser and at 50 kW/cm2 for a Tisapphire laser. These performance are high enough for cw Ti:sapphire oscillators. Furthermore, this mirror had a high damage-threshold (2.7 to 17 J/cmz, 720 to 900 nm, 10-nsec) suitable for pulsed laser. Such a high damage threshold in broadband mirrors could not be realized without the novel design for suppressing the interfered electric-field in the coating. Two types of 2ow

Optical backplane technologies

Abstract: Tho6 and heavy hole subbands. (b)-Design of laser; 1-Semitransparent metai mesh mirror; 2-absorbing film; 3-Si plate as gap; 3-p-Ge crystal; 4-spherical mirror. Fig. 1. (a)-Radiative transitions of the holes in germanium between light J. Chrostowski, W. Robertson, IC. Bamard, I? Palacharla, l? Myslinski, S. Boothroyd, Institute for Information Technology, National Research Council, Ottawa, Ont. Canada K1A OR6

Semiconductor microcavity light-emitting structures

Abstract: Over the last decade considerable advances have been made in the area of semiconductor lasers as a result of tailoring the electronic structure of the active medium. This has been accomplished through the use of quantum confinement and built-in strain. There has been less emphasis on altering the photonic properties to improve laser performance. In this paper we examine the potential of a surface-emitting microcavity structure with submicron lateral dimensions for improving laser performance. We find that as the lateral dimensions are decreased, the photon density of states starts to change. In particular, strongly resonant states associated with Bragg reflection begin to dominate the photon spectrum. By placing the resonance peak close to the gain peak in the active quantum well region, a number of laser properties can be altered. The dimensions at which the changes start to be significant is about (lambda) /n a , where n a is the refractive index of the active region. A study of how the threshold current, dynamic characteristics and laser linewidth change as a function of the microcavity dimensions is presented. Our studies show that the spontaneous emission factor (beta) approaches a value of approximately equals 0.5 for small structures with high mirror reflectivities. This in turn results in essentially zero threshold lasing for a microcavity with lateral dimensions < 0.3 micrometers (for emission at 1.3 eV). The laser linewidth increases as (beta) decreases, but the increase is not proportional to (beta) , and even for small structures, the linewidth is expected to be in the range of 100 MHz to 1 GHz, which may be adequate for many applications. The -3 dB response of the 0.3 micrometers laser exceeds 40 GHz.

Microcavity laser physics

Abstract: Microcavity lasers have been predicted to offer low threshold current, high quantum efficiency and high modulation bandwidth. In this report we review the physics underlying microcavity device behavior. Specifically we cover dipole-field coupling for both localized (point) dipoles and extended dipoles. In general, optical pumping of the devices is required to create extended dipoles. We also outline the difference between the weak (irreversible) coupling regime and the strong (reversible) regime. For photonic application the intermediate, superradiant regime is perhaps more interesting than the strong coupling regime. Finally, we describe our recent experimental efforts to make high quantum efficiency devices by creating extended excitonic dipoles in electrically pumped devices.