Showing papers on "Optical microcavity published in 2002"
TL;DR: In this paper, the coupling of optical waveguides to ring resonators holds the promise of a new generation of switches (modulators) which employ orders of magnitude smaller switching (modulation) voltages (or control intensities).
Abstract: The coupling of optical waveguides to ring resonators holds the promise of a new generation of switches (modulators) which employ orders of magnitude smaller switching (modulation) voltages (or control intensities). This requires a means for voltage (or intensity) control of the coupling between the waveguide and the resonator. Schemes for achieving such control are discussed.
621 citations
TL;DR: In this paper, a single semiconductor quantum dot was coupled to a three-dimensionalally confined optical mode in a micropost microcavity to produce triggered single photons, and the efficiency of emitting single photons into a single-mode traveling wave was approximately 38%.
Abstract: We have demonstrated efficient production of triggered single photons by coupling a single semiconductor quantum dot to a three-dimensionally confined optical mode in a micropost microcavity. The efficiency of emitting single photons into a single-mode traveling wave is approximately 38%, which is nearly 2 orders of magnitude higher than for a quantum dot in bulk semiconductor material. At the same time, the probability of having more than one photon in a given pulse is reduced by a factor of 7 as compared to light with Poissonian photon statistics.
614 citations
TL;DR: In this paper, the authors showed that sharp and asymmetric line shapes can be created in the response function by placing two partially reflecting elements into the waveguides, and numerically demonstrated this effect by simulating the propagation of electromagnetic waves in a photonic crystal.
Abstract: We show that, for an optical microcavity side coupled with a waveguide, sharp, and asymmetric line shapes can be created in the response function by placing two partially reflecting elements into the waveguides. In such a system, the transmission coefficient varies from 0% to 100% in a frequency range narrower than the full width of the resonance itself. We numerically demonstrate this effect by simulating the propagation of electromagnetic waves in a photonic crystal.
481 citations
TL;DR: A novel integrated optical sensor based on a cylindrical microcavity (MC) that sustains so-called whispering-gallery modes (WGMs), in which the energy of the optical field can be efficiently stored is proposed.
Abstract: A novel integrated optical sensor based on a cylindrical microcavity (MC) is proposed. A MC sustains so-called whispering-gallery modes (WGMs), in which the energy of the optical field can be efficiently stored. By monitoring the scattering intensity from the MC, one can detect minute changes in the refractive index of the WGM, for instance, as a result of analyte adsorption. Measurement of a change in refractive index of as little as 1024 is demonstrated experimentally. The MC-based integrated optical sensor may have a size of approximately 8 mm, and it is rugged and inexpensive.
270 citations
TL;DR: It is shown that acoustical phonons can be confined in such layered structures when the spacer thickness is an integer multiple of the acoustic half-wavelength at the center of one of the superlattice folded minigaps.
Abstract: Extending the idea of optical microcavities to sound waves, we propose a phonon cavity consisting of two semiconductor superlattices enclosing a spacer layer. We show that acoustical phonons can be confined in such layered structures when the spacer thickness is an integer multiple of the acoustic half-wavelength at the center of one of the superlattice folded minigaps. We report Raman scattering experiments that, taking profit of an optical microcavity geometry, demonstrate unambiguously the observation of a phonon-cavity confined acoustical vibration in a GaAs/AlAs based structure. The experimental results compare precisely with photoelastic model calculations of the Raman spectra.
219 citations
TL;DR: In this article, the effect of exciton-phonon interactions on reversible quantum dot cavity coupling was analyzed without making a Born-Markov approximation, based on a polaron operator technique that has been used to study the spin-boson Hamiltonian.
Abstract: A quantum dot strongly coupled to a single high-finesse optical microcavity mode constitutes a new fundamental system for quantum optics. Here, the effect of exciton-phonon interactions on reversible quantum dot cavity coupling is analyzed without making a Born-Markov approximation. The analysis is based on a polaron operator technique that has been used to study the ``spin-boson'' Hamiltonian. For bulk acoustic phonons and for a large class of confined phonon models, we find that vacuum-Rabi splitting persists even in the presence of a large Stokes shift and at an appreciable temperature, but its magnitude is exponentially suppressed by the electron-phonon coupling strength.
185 citations
TL;DR: In this article, a modified single-defect two-dimensional photonic crystal slab structure is theoretically and experimentally studied, and the non-degenerate hexapole mode, a special type of whispering gallery mode, has a high quality factor.
Abstract: The resonant modes found in a modified single-defect two-dimensional photonic crystal slab structure are theoretically and experimentally studied. There exist several modes in the band gap: doubly degenerate (dipole and quadrupole modes) and nondegenerate (hexapole and monopole modes). Among them, the monopole mode specifically attracts our interest because of its nondegeneracy, good coupling with the gain medium, and existence of the intensity minimum at the center of the cavity, which would open up the chance for the electrically driven single-defect laser. The nondegenerate hexapole mode, a special type of whispering gallery mode, has a very high quality factor. We have fabricated two types of modified single-defect lasers, i.e., air-based free-standing and SiO/sub 2/-based epoxy-bonded structures. Rich lasing actions in both structures are experimentally observed under optically pulsed pumping conditions at room temperature. In the free-standing slab structure, photons are strongly confined in vertical direction, and the lasing operations of all resonant modes with low thresholds are obtained. Especially, the nondegenerate monopole-mode laser is confirmed to have a large spontaneous emission factor of >0.06, estimated by analyzing rate equations. In the SiO/sub 2/-based slab structure, thermal properties are improved at the expense of vertical losses.
151 citations
TL;DR: In this article, the authors numerically model the effect of surface plasmon (SP) modes on the efficiency of organic light-emitting diodes and show that SP modes can significantly detract from device efficiency, particularly those based on small molecules.
Abstract: Organic light-emitting diodes typically take the form of an optical microcavity in which one layer is a metallic cathode. Coupling between emissive species in the light emitting layer and surface plasmon (SP) modes associated with the metallic cathode result in a loss of efficiency; an aspect often discussed but not so far fully quantified. Here we numerically model the extent of this problem, both for organic light-emitting diodes based on small molecules (Alq/sub 3/) and those based on conjugated polymers (MEH-PPV). We show that SP modes can significantly detract from device efficiency, particularly those based on small molecules. We then report measurements of photo- and electroluminescence from organic light-emitting diodes incorporating wavelength scale periodic structure. These data demonstrate the existence of the SP modes in organic light-emitting diodes. Finally we consider ways in which the problems associated with SPs might be overcome, and may even be turned to advantage.
140 citations
TL;DR: These results suggest that single nitrogen-bound excitons are well suited for cavity quantum electrodynamics experiments and find resolution-limited photoluminescence lines which display photon antibunching under continuous optical pumping.
Abstract: We demonstrate the generation of triggered single photons at a predetermined and well defined energy using the radiative recombination of single nitrogen-bound excitons in a semiconductor. The nitrogen atoms are embedded in a ZnSe quantum well structure and were excited by nonresonant optical pumping (82 MHz) at low temperature (4 K). We find resolution-limited photoluminescence lines ($280\text{ }\ensuremath{\mu}\mathrm{e}\mathrm{V}$) which display photon antibunching under continuous optical pumping. Our results also suggest that single nitrogen-bound excitons are well suited for cavity quantum electrodynamics experiments.
85 citations
Patent•
03 Apr 2002
TL;DR: In this paper, the authors used an optical coupler and a film for evanescently coupling light to or from an optical or electro-optical device, where the film is connected to the coupler surface as a spacer for setting the distance between the optical couplers and the optical or EH devices.
Abstract: This application teaches systems and techniques that use an optical coupler and a film for evanescently coupling light to or from an optical or electro-optical device The film is connected to the coupler surface as a spacer for setting the distance between the optical coupler and the optical or electro-optical device
55 citations
TL;DR: In this article, the spontaneous emission spectra for a single quantum well embedded in a planar microcavity with Bragg mirrors at 300 K were presented, and the confinements of vacuum fields and electrons were considered together.
Abstract: This article presents the spontaneous emission spectra for a single quantum well embedded in a planar microcavity with Bragg mirrors at 300 K. The confinements of vacuum fields and electrons are considered together in the microcavity. An estimate of the spontaneous emission coupling factor is given. We find that the maximum scaling of the spontaneous emission coupling factor is 0.0055.
TL;DR: Propagation of a light pulse through a high-Q optical microcavity containing a few cold atoms (N<10) in its cavity mode is investigated experimentally and up to 170 ns propagation lead time ("superluminal"), and 440 ns propagation delay time (subluminals) are observed.
Abstract: Propagation of a light pulse through a high-Q optical microcavity containing a few cold atoms (N<10) in its cavity mode is investigated experimentally. With less than ten cold rubidium atoms launched into an optical microcavity, up to 170 ns propagation lead time ("superluminal"), and 440 ns propagation delay time (subluminal) are observed. Comparison of the experimental data with numerical simulations as well as future experiments are discussed.
TL;DR: The model fully take into account the dependence of thephase change that occurs on reflection on angle and wavelength for both s and p polarization, as well as on dispersion in the organic layers.
Abstract: Organic microcavity light-emitting diodes typically exhibit a blueshift of the emitting wavelength with increasing viewing angle. We have modeled the shift of the resonance wavelength for several metal mirrors. Eight metals (Al, Ag, Cr, Ti, Au, Ni, Pt, and Cu) have been considered as top or bottom mirrors, depending on their work functions. The model fully takes into account the dependence of the phase change that occurs on reflection on angle and wavelength for both s and p polarization, as well as on dispersion in the organic layers. Different contributions to the emission wavelength shift are discussed. The influence of the thickness of the bottom mirror and of the choice and thickness of the organic materials inside the cavity has been investigated. Based on the results obtained, guidelines for a choice of materials to reduce blueshift are given.
TL;DR: This experimental demonstration of controlling the cavity output intensity of one laser beam with the intensity of another laser beam in a composite system consisting of a collection of three-level ?
Abstract: We present our experimental demonstration of controlling the cavity output intensity of one laser beam with the intensity of another laser beam in a composite system consisting of a collection of three-level ?-type rubidium atoms and an optical ring cavity. When the intensity of the controlling beam is modulated with a square waveform, the cavity output power switches on and off (with a distinction ratio better than 20:1) between two steady-state values. This all-optical switching effect is the result of combined absorption and enhanced Kerr nonlinearity near resonance in such three-level atomic systems because of atomic coherence and can find applications in optical communication and optical computation.
TL;DR: In this paper, an asymmetric Fabry-Perot microcavity using total reflection was constructed and its optical properties were investigated, and the structure was considered to be a total-reflection-type 1-D photonic crystal.
Abstract: We produced an asymmetric Fabry-Perot microcavity using total reflection, and its optical properties were investigated. The structure is considered to be a total-reflection-type 1-D photonic crystal. An electric-field enhancement of incident light in a defect layer installed inside the photonic crystal was observed by fluorescence emission from dye molecules doped into the defect layer division. We confirmed that the incident light intensity was strengthened by about 63 times in the defect layer.
TL;DR: In this article, the effect of various geometrical parameters on the resonator performance is investigated in detail, and the characteristic electric field patterns that occur at major and minor resonance wavelengths are investigated.
Abstract: Two dielectric waveguides that are evanescently coupled to a square or rectangular region of increased refractive index can serve as a very compact integrated optical microresonator. We consider these devices in a spatial two-dimensional setting, where a rigorous mode expansion technique enables accurate and quite efficient numerical simulations of these configurations. The paper is concerned with single resonator units as well as with an add-drop filter constructed by cascading two square cavities. Besides calculating the power transmission spectra, we try to document as far as possible the characteristic electric field patterns that occur at major and minor resonance wavelengths. The influence of the various geometrical parameters on the resonator performance is investigated in detail.
TL;DR: In this paper, the optical properties of wide-gap semiconductor films on metal substrates were investigated experimentally by infrared spectroscopy, Raman scattering, and femtosecond (FSE) techniques as well as theoretically in the framework of linear crystal optics.
Abstract: The optical properties of wide-gap semiconductor films on metal substrates were investigated experimentally by infrared spectroscopy, Raman scattering, and femtosecond spectroscopy techniques as well as theoretically in the framework of linear crystal optics. The optical spectra of such planar structures (microresonators) were shown to bear information on electromagnetic excitations of both the surface and the volume of the structure. The optical spectra are determined by the interaction of all dipole-active excitations of the component materials with the electromagnetic modes of the microresonator, which in turn are determined by the permittivities of each component material, microcavity (microresonator) thickness, and the experimental conditions.
TL;DR: In this paper, a bidirectional coupled mode theory (CMT) based on the guided fixed-frequency modes of the two port waveguides and the cavity segment is proposed to solve for the power transmission of the resonators.
TL;DR: In this paper, an optically pumped laser emission from a microcavity containing an oriented layer of the liquid crystalline conjugated polymer poly(9,9-dioctylfluorene) was studied.
Abstract: We present a study of optically pumped laser emission from a microcavity containing an oriented layer of the liquid crystalline conjugated polymer poly(9,9-dioctylfluorene). The birefringence of the oriented polymer results in the definition of two cavity modes with electric vectors polarized perpendicular and parallel to the alignment direction. At high excitation density, the emission intensity from the cavity mode polarized parallel to the orientation direction increases rapidly compared to the orthogonal polarized mode and its linewidth narrows from 8 to 2 nm. We identify the parallel-polarized emission as laser action with a threshold excitation density of 7.8×1019 cm−3.
TL;DR: The fabrication of Fabry-Perot microcavity structures with the organic light-emitting material tris-(8-hydroxyquinoline) aluminum (Alq3) and derive their optical properties by measuring their photoluminescence (PL) and absorption.
Abstract: We report the fabrication of Fabry-Perot microcavity structures with the organic light-emitting material tris-(8-hydroxyquinoline) aluminum (Alq3) and derive their optical properties by measuring their photoluminescence (PL) and absorption. Silver and a TiO2-SiO2 multilayer were used as metal and dielectric reflectors, respectively, in a Fabry-Perot microcavity structure. Three types of microcavity were prepared: type A consisted of [air|Ag|Alq3|Ag|glass]; type B, of [air|dielectric|Alq3|dielectric|glass]; and type C, of [air|Ag|Alq3|dielectric|glass]. A bare Alq3 film of [air|Alq3|glass] had its PL peak near 514 nm, and its full width at half-maximum (FWHM) was 80 nm. The broad FWHM of a bare Alq3 film was reduced to 15–27.5, 7–10.5, and 16–16.6 nm for microcavity types A, B, and C, respectively. Also, we could control the PL peak of the microcavity structure by changing the spacer thickness, the amount of phase change on reflection, and the angle of incidence.
TL;DR: In this paper, the authors report absolute measurements of thermal-mechanical noise in microelectromechanical systems with an optical microcavity technique that has a resolution on the order of tens of femtometers per root hertz.
Abstract: We report absolute measurements of thermal-mechanical noise in microelectromechanical systems. The devices are studied with an optical microcavity technique that has a resolution on the order of tens of femtometers per root hertz. The measured noise spectrum agrees with the calculated noise level to within 25%, a discrepancy most likely due to uncertainty in the effective dynamic mass of the vibrating bridge. These measurements demonstrate that thermal-mechanical noise can be the dominant noise source in actuated microelectromechanical devices.
TL;DR: In this paper, the angular dependences of the electroluminescence and the emission patterns versus viewing angle in an optical microcavity OLED were studied, and a device with sharply directed emission vertical to an emission surface was fabricated.
Abstract: An optical microcavity structure was used in organic light emitting diodes. We succeeded in fabricating a device with sharply directed emission vertical to an emission surface. The device shows green emission (bright green) at normal position which turns red (bright red) at the 30° position. The angular dependences of the electroluminescence and the emission patterns versus viewing angle in the microcavity OLED were studied. The resonance wavelength λ decreases with viewing angle. The emission peak at 490 nm is directed vertically to the device surface more sharply than that at 632 nm. The microcavity structure shows non-Lambertian emission. The spectra appear more blue off-axis and the intensity of the green-like emission decreases rapidly with increasing viewing angle. A significantly narrow linewidth of 7.4 nm in the 0° direction for the 490 nm peak was observed. The full-widths at half maximum (FWHM) of the green-like spectra are much smaller than those of the red-like ones, indicating better cavity quality.
TL;DR: In this article, the mutual coupling between a microcavity and a waveguide realized in a two-dimensional photonic crystal on an InP membrane is demonstrated by generating guided or cavity modes by photoluminescence and by measuring locally the diffraction losses.
Abstract: We demonstrate the mutual coupling between a microcavity and a waveguide realized in a two-dimensional photonic crystal on an InP membrane. Coupling processes are evidenced by generating guided or cavity modes by photoluminescence and by measuring locally the diffraction losses. Depending on the transfer and loss dynamics, different coupling processes are found. Finite difference time-domain simulations and additional polarization resolved luminescence measurements are performed in order to further investigate the coupling procedure.
Patent•
25 Feb 2002
TL;DR: In this article, the authors proposed a quantum well structure for a semiconductor optical element having an optical waveguide layer in which light in a wavelength band of 1.3 μm is not absorbed and the light is effectively confined.
Abstract: PROBLEM TO BE SOLVED: To provide a semiconductor optical element having an optical waveguide layer in which light in a wavelength band of 1.3 μm is not absorbed and the light is effectively confined. SOLUTION: The semiconductor optical element in which light having the wavelength λLD is guided into a light absorption layer 2 through an optical waveguide layer 3, includes a semiconductor substrate 1, an optical waveguide layer which is provided on the semiconductor substrate and has a quantum well structure including a well layer and a barrier layer, a light absorption layer provided adjacent to the optical waveguide layer on the semiconductor substrate so that the light passing through the optical waveguide layer is made incident, a clad layer 4 provided on the optical waveguide layer, and on the light absorption layer, and a pair of electrodes provided to interpose the light absorption layer. The component wavelength λ g of the well layer is longer than the wavelength λLD and the transition energy between the ground level of a conduction band and the ground level of a valence band in the well layer is made larger than the photon energy which the light having the wavelength λLD has. COPYRIGHT: (C)2003,JPO
TL;DR: In this paper, high differential efficiency quantum dot microcavity light emitting diodes were used to reduce carrier diffusion in small oxide-apertured micro-cavities.
Abstract: Data are presented on high differential efficiency quantum dot microcavity light emitting diodes. The data show that differential efficiencies >16% can be achieved by the use of quantum dots to reduce carrier diffusion in small oxide-apertured microcavities. The measured efficiencies are sensitive to both microcavity tuning of the resonance peak to the quantum dot light emitters, and nonradiative recombination effects brought on by temperature, bias current, and edge effects. The peak efficiencies are obtained at a resonance temperature of ∼160 K.
TL;DR: In this paper, a novel class of composites for optics, microcavities doped with metal fractal aggregates, is studied, where broad-band Stokes and anti-Stokes emission from (Ag colloidal aggregates)/(adsorbed molecules)/(micro-cavity) composite at low-intensity cw and pulse laser excitation has been found.
Abstract: A novel class of composites for optics, microcavities doped with metal fractal aggregates, is studied. Lasing and broad-band Stokes and anti-Stokes emission from (Ag colloidal aggregates)/(adsorbed molecules)/(micro-cavity) composite at low-intensity cw and pulse laser excitation has been found. At 633 nm cw excitation wavelength the emission spectrum contains many peaks, spanning a range from wavelength 200 nm to 800 nm. Experiments with pulse excitation of Ag/dye/microcavity composite show that the duration of the observed broad-band anti-Stokes emission significantly exceeds the pump pulse duration, dye molecule fluorescence time, and relaxation times in silver particles. It may be interpreted as a luminescence governed by long-living triplet states of dye molecules. These observations were made possible by use of a fractal-microcavity composite, where coupling the localized plasmon modes in fractal aggregates with microcavity resonances is provided. The important role of multiphoton resonant transitio...
TL;DR: In this paper, the authors describe the internal fields created when two ultra-short pulses of light illuminate a spherical micro-cavity, with the time delay between the two pulses as a parameter.
TL;DR: In this article, a detailed study of the Raman-scattering spectra by acoustical phonons in finite-size GaAs/AlAs superlattices is presented.
Abstract: We present a detailed study of the Raman-scattering spectra by acoustical phonons in finite-size GaAs/AlAs superlattices. The scattering geometry relies on an optical microcavity to enhance the Raman efficiency and to access the ${q}_{z}=0$ forward-scattering contribution. The results are analyzed using a photoelastic model for the Raman efficiency, which takes into account the superlattices finite size, the cavity confined optical field, and the acoustical-phonon displacements including the elastic modulation. The latter are derived from a matrix method implementation of the elastic continuum model for the complex layered structure. The calculations provide a complete description of the main experimental results that include: (i) the observation of low-energy oscillations, (ii) the presence of three main Raman lines in the first folded-phonon spectral region, (iii) the broadening of the Raman peaks, and (iv) the spectral shift of the lines with respect to the infinite superlattice. In addition, the observed asymmetry of the main central peak is understood as due to a ${q}_{z}$-nonconservation induced violation of the expected center-zone Raman selection rule. Besides providing a clear observation of the finite-size effects on superlattice acoustical phonons, the reported results demonstrate the use of microcavity geometries to access center-zone minigap excitation in layered structures.
TL;DR: In this article, the linear and nonlinear optical properties of pseudoisocyanine (PIC) aggregates in 1-D distributed feedback microcavities, photonic crystal slabs are investigated.
Abstract: The linear and nonlinear optical properties of pseudoisocyanine (PIC) J aggregates in 1-D distributed feedback (DFB) microcavities, photonic crystal slabs are investigated. The linear optical properties are well described by the DFB cavity-polaritons in the slabs. A polariton mode splitting of 50 meV and a photonic band gap of 30 meV are observed in PIC J aggregates dispersed in a polyvinyl-alcohol matrix. In the pump and probe experiments, we resonantly excited the cavity mode observed at the low energy side of the excitonic resonance, the virtual-exciton excitation condition. The response time is about 0.5 ps, which is approximately equal to the pump-pulse duration. We find the enhancement of the optical nonlinearity to be one-order of magnitude in the microcavity. Excitation of the dielectric-band mode is effective in enhancing the nonlinearity with an ultrafast response.
Patent•
28 Jan 2002TL;DR: In this paper, the authors disclose a new structure that allows the creation of sharp and asymmetric lineshapes in optical microcavity systems, which can vary from 0% to 100% in a frequency range that is narrower than the full width of the resonance itself.
Abstract: We disclose a new structure that allows the creation of sharp and asymmetric lineshapes in optical microcavity systems. In this structure, the response function can vary from 0% to 100% in a frequency range that is narrower than the full width of the resonance itself. Therefore, an optical switch, based upon this structure, may require far less frequency shift to operate, compared with conventional microcavity-based structures. This method may also be used to improve the sensitivity of optical sensors based upon microcavity structures.