Showing papers on "Photonic crystal published in 1997"
TL;DR: An effective-index model confirms that an all-silica optical fiber made by embedding a central core in a two-dimensional photonic crystal with a micrometer-spaced hexagonal array of air holes can be single mode for any wavelength.
Abstract: We made an all-silica optical fiber by embedding a central core in a two-dimensional photonic crystal with a micrometer-spaced hexagonal array of air holes. An effective-index model confirms that such a fiber can be single mode for any wavelength. Its useful single-mode range within the transparency window of silica, although wide, is ultimately bounded by a bend-loss edge at short wavelengths as well as at long wavelengths.
2,905 citations
TL;DR: In this article, the authors describe the photonic bandgap as a periodicity in dielectric constant, which can create a range of 'forbidden' frequencies called a photonic Bandgap.
Abstract: Photonic crystals are materials patterned with a periodicity in dielectric constant, which can create a range of 'forbidden' frequencies called a photonic bandgap. Photons with energies lying in the bandgap cannot propagate through the medium. This provides the opportunity to shape and mould the flow of light for photonic information technology.
2,891 citations
TL;DR: In this paper, the authors measured microcavity resonances in two-and three-dimensional photonic-bandgap (PBG) structures integrated directly into a sub-micrometre-scale silicon waveguide.
Abstract: Confinement of light to small volumes has important implications for optical emission properties: it changes the probability of spontaneous emission from atoms, allowing both enhancement and inhibition. In photonic-bandgap (PBG) materials1,2,3,4 (also known as photonic crystals), light can be confined within a volume of the order of (λ/2n)3, where λ is the emission wavelength and n the refractive index of the material, by scattering from a periodic array of scattering centres. Until recently5,6, the properties of two- and three-dimensional PBG structures have been measured only at microwave frequencies. Because the optical bandgap scales with the period of the scattering centres, feature sizes of around 100 nm are needed for manipulation of light at the infrared wavelength (1.54 µm) used for optical communications. Fabricating features this small requires the use of electron-beam or X-ray lithography. Here we report measurements of microcavity resonances in PBG structures integrated directly into a sub-micrometre-scale silicon waveguide. The microcavity has a resonance at a wavelength of 1.56 µm, a quality factor of 265 and a modal volume of 0.055 µm3. This level of integration might lead to new photonic chip architectures and devices, such as zero-threshold microlasers, filters and signal routers.
979 citations
TL;DR: In this article, a thin slab of two-dimensional photonic crystal is shown to alter drastically the radiation pattern of spontaneous emission, and spontaneous emission can be coupled entirely to free space modes, resulting in a greatly enhanced extraction efficiency.
Abstract: A thin slab of two-dimensional photonic crystal is shown to alter drastically the radiation pattern of spontaneous emission. More specifically, by eliminating all guided modes at the transition frequencies, spontaneous emission can be coupled entirely to free space modes, resulting in a greatly enhanced extraction efficiency. Such structures might provide a solution to the long-standing problem of poor light extraction from high refractive-index semiconductors in light-emitting diodes.
637 citations
TL;DR: In this paper, the optical properties of packed monodisperse silica submicron spheres were investigated by means of optical transmission measurements and the results were compatible with a three dimensional face centered cubic order in these solid structures.
Abstract: In this letter, we investigate the optical properties of packed monodisperse silica submicron spheres by means of optical transmission measurements. The results are compatible with a three dimensional face centered cubic order in these solid structures. The lattice parameter of these structures, and therefore their optical properties, can be easily tuned through the sphere size (between 200 and 700 nm) thus covering the whole visible and near infrared spectrum.
319 citations
TL;DR: In this paper, the authors presented a preliminary guide to realize microcavity semiconductor lasers exhibiting spontaneous emission control effects, which includes theoretical consideration on the effects; processing techniques for semiconductor micro-cavities; and some demonstrations of photonic crystal and microdisk cavity.
Abstract: This paper presents a preliminary guide to realize microcavity semiconductor lasers exhibiting spontaneous emission control effects. It includes: 1) theoretical consideration on the effects; 2) processing techniques for semiconductor microcavities; and 3) some demonstrations of photonic crystal and microdisk cavity. It was shown that, even with a spectral broadening of electron transition, thresholdless lasing operation and alternation of spontaneous emission rate are expected in a cavity satisfying the single mode condition that only one mode is allowed in the transition spectrum. An ideal three-dimensional (3-D) photonic crystal has the potentiality for realizing this condition. In two-dimensional (2-D) crystals and microdisk cavities, thresholdless operation is also expected, but the alternation of spontaneous emission rate may be negligible due to the insufficient optical confinement. In the experiment, some processing techniques for GaInAsP-InP system were investigated and methane-based reactive ion beam etching was selected because of the smooth sidewalls and adaptability to arbitrary structures. A GaInAsP-InP 2-D photonic crystal constructed by submicron columns was fabricated using this method. Owing to the slow surface recombination of this material, a polarized photoluminescence and peculiar transmission spectra were observed at room temperature (RT), which can be explained by a photonic band calculation. However, some technical improvement is necessary for clear demonstration of photonic bandgap, which is minimally required for device applications. In contrast to this, a GaInAsP-InP microdisk cavity of 2 /spl mu/m in diameter, which corresponds to the cavity volume 2.5 times the single-mode condition, has achieved RT lasing with threshold current as low as 0.2 mA. Further reduction of diameter and realization of continuous-wave (CW) operation will provide a significant regime for the observation of spontaneous emission control effects.
239 citations
TL;DR: Three-dimensional periodic microstructures of aluminum oxide, which are important for creating photonic band-gap structures (PBGs), were fabricated by laser rapid prototyping by means of laser-induced direct-write deposition from the gas phase.
Abstract: Three-dimensional periodic microstructures of aluminum oxide, which are important for creating photonic band-gap structures (PBGs), were fabricated by laser rapid prototyping by means of laser-induced direct-write deposition from the gas phase. The structures consisted of layers of parallel rods forming a face-centered tetragonal lattice with lattice constants of 66 and 133 micrometers. These structures showed transmission minima centered around 4 terahertz (75 micrometers) and 2 terahertz (150 micrometers), respectively. PBGs will allow precise control of the optical properties of materials, including lasers without threshold.
237 citations
TL;DR: In this article, the photonic band gap phenomenon in the visible range in a three-dimensional dielectric lattice formed by close-packed spherical silica clusters was investigated.
Abstract: We report on the photonic band gap phenomenon in the visible range in a three-dimensional dielectric lattice formed by close-packed spherical silica clusters. The spectral position and the spectral width of the optical stop band depend on the direction of light propagation with respect to the crystal axes of opal, and on the relative cluster-to-cavity refraction index n. Manifestations of the photonic pseudogap have been established for both transmission and emission spectra. The stop band peak wavelength shows a linear dependence on n. Transmission characteristics of the lattice have been successfully simulated by numerical calculations within the framework of a quasicrystalline approximation. @S1063-651X~97!13805-3#
229 citations
TL;DR: In this paper, a two-dimensional triangular lattice in GaAs was constructed with a simple holographic recording of a very small number of optical plane waves, and appeared in this regard as the simplest holograms.
Abstract: Photonic band gap materials are holograms with extremely high refractive index contrasts. The refractive index function can be approximated by a small number of plane waves, as a consequence of the photonic crystal periodicity. Photonic crystals can hence be constructed with a simple holographic recording of a very small number of optical plane waves, and appear in this regard as the simplest holograms. Various photonic band gap structures are theoretically analysed and those concepts are illustrated experimentally with the fabrication of a two-dimensional triangular lattice in GaAs. The extension of the method to the three-dimensional diamond structure is discussed.
210 citations
TL;DR: In this article, the influence of defects in a photonic crystal was studied using a finite set of parallel cylinders and the results showed that a slight local change in the crystal period can be used for the realization of devices that radiate energy in a very narrow angular range.
Abstract: We use a rigorous method for diffraction by a finite set of parallel cylinders to study the influence of defects in a photonic crystal. The method allows us to give an accurate description of all the characteristics of the electromagnetic field (near-field map, scattered field, and energy flow). The localized resonant modes can also be computed. We show some of their symmetry properties and the influence of coupling between two neighboring defects. Finally, an example is given, which shows that a slight local change in the crystal period can be used for the realization of devices that radiate energy in a very narrow angular range.
204 citations
TL;DR: In this paper, the authors present quantitative measurements of the interaction between a guided optical wave and a two-dimensional photonic crystal using spontaneous emission of the material as an internal point source.
Abstract: We present quantitative measurements of the interaction between a guided optical wave and a two-dimensional photonic crystal using spontaneous emission of the material as an internal point source. This is the first analysis at near-infrared wavelengths where transmission, reflection, and inplane diffraction are quantified at the same time. Low transmission coincides with high reflection or in-plane diffraction, indicating that the light remains guided upon interaction. Also, good qualitative agreement is found with a two-dimensional simulation based on the transfer matrix method. [S0031-9007(97)04591-2]
TL;DR: In this article, coherent control of spontaneous emission from a three-level atom with one resonant frequency near the edge of a photonic band gap was demonstrated, where spontaneous emission can be totally suppressed or strongly enhanced depending on the relative phase between the control and pump laser fields.
Abstract: We demonstrate coherent control of spontaneous emission from a three-level atom with one resonant frequency near the edge of a photonic band gap. As a result of quantum interference and photon localization, spontaneous emission can be totally suppressed or strongly enhanced depending on the relative phase between the control and pump laser fields. The fractionalized steady state inversion of the atom depends sensitively on the initial conditions, suggesting the possibility of a phase-sensitive, optical memory device on the atomic scale.
TL;DR: In this paper, it was found through a vector integral-equation analysis and the reciprocity theorem that the gain of a microstrip antenna can be greatly enhanced with a photonic band gap material layer either as the substrate or the superstrate.
Abstract: It is found through a vector integral-equation analysis and the reciprocity theorem that the gain of a microstrip antenna can be greatly enhanced with a photonic band-gap material layer either as the substrate or the superstrate. The beam angle is found to coincide with that of a leaky-wave mode of a planar-grating structure. This observation suggests that high gain is due to the excitation of strong leaky-wave fields.
TL;DR: In this paper, the spontaneous emission from a three-level atom embedded in a photonic band gap structure is studied, where interference between two transitions leads to quasiperiodic oscillations of population between the two upper levels with large amplitudes.
Abstract: The spontaneous emission from a three-level atom embedded in a photonic band gap structure is studied. Interference between two transitions leads to quasiperiodic oscillations of population between the two upper levels with large amplitudes. The spontaneous emission of the atom is characterized by three components in the radiated field: a localized part, a traveling pulse, and a $(1/\sqrt{t}{)}^{3}$ decaying part. An analytical expression for the localization distance of the localized field is obtained. The energy velocity for the traveling pulse could be close to zero. By selecting an appropriate initial superposition state, a large amount of population trapping can be achieved.
TL;DR: In this article, the optical gain of CdS quantum dots (QDs) embedded inside the interstitials between the silica spheres was measured and the observed effect was attributed to gain enhancement caused by multiple coherent Bragg scattering of light in the periodic photonic crystal.
Abstract: The three-dimensional photonic crystals used in this study were synthetic opals, composed of submicron silica spheres, close-packed in a face-centered cubic structure with a period of 200 nm, that exhibit photonic stopbands around 600 nm. We present measurements of the optical gain of CdS quantum dots (QDs) embedded inside the interstitials between the silica spheres. Unlike the usual gain spectra of CdS QDs in glass matrices, which display maximum gain at energies of the first quantum-confined transitions, for QDs embedded in photonic crystals the gain maximum is shifted toward the high-frequency edge of the photonic stopband (2.2 eV) far below the absorption edge of the semiconductor (2.5 eV). Studies of temperature, intensity, and orientation dependencies of the gain spectra allow one to ascribe the observed effect to gain enhancement caused by multiple coherent Bragg scattering of light in the periodic photonic crystal.
TL;DR: In this article, it was shown in the wrong orientation that Figure 6 in this review should be rotated 90° anticlockwise and the figure as printed should be turned 90° counter-clockwise.
Abstract: Nature 386143–149 (1997) Figure 6 in this Review was shown in the wrong orientation The figure as printed should be rotated 90° anticlockwise
Patent•
12 Dec 1997TL;DR: In this article, a nonlinear dielectric material is incorporated within a photonic crystal as a means of changing the refractive index of a defect in order to tune the resonant mode of the microcavity.
Abstract: A nonlinear dielectric material is incorporated within a photonic crystal as a means of changing the refractive index of a defect In this way, the resonant frequency can be easily adjusted, after fabrication, by external mechanisms (either optical or electronic) The ability to tune the frequency of a resonant mode is useful for constructing photonic integrated devices, thus the invention enables the use of a photonic-crystal microcavity for such purposes In one embodiment there is provided a photonic crystal having a periodic dielectric structure, and a defect positioned within the structure to define a microcavity The defect includes a nonlinear material and being adapted to have an induced variation in index of refraction so as to tune the resonant mode of the microcavity
Patent•
24 Oct 1997
TL;DR: In this article, a photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided, where the introduction of the periodicity defect region into this photonic Band gap structure creates a sharp transmission resonance within the corresponding band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size.
Abstract: A photonic band gap structure device and method for delaying photonic signals of a predetermined frequency and a predetermined bandwidth by a predetermined delay is provided. A Fabry-Perot delay line device has several regions of periodically alternating refractive material layers which exhibit a series of photonic band gaps and a periodicity defect region, interposed between the regions of periodically alternating refractive material layers. The Fabry-Perot delay line device imparts a predetermined delay to photonic signals that pass therethrough. The introduction of the periodicity defect region into this photonic band gap structure creates a sharp transmission resonance within the corresponding photonic band gap of the structure and causes at least an order of magnitude improvement in photonic signal delay for a band-edge delay line device of similar size. Variable photonic delays to multiple photonic signals are also generated by this Fabry-Perot delay line device. In addition, a photonic signal delay device based on an optical fiber grating structure is provided.
TL;DR: In this article, the authors used multiple tilted x-ray lithography exposures in order to construct structures with photonic band gaps in the infrared region, and the fitted values of the dielectric constant were in good agreement with the transmission measurements.
Abstract: We have developed a new microfabrication technique for the construction of three-dimensional photonic crystals. In particular, we used multiple tilted x-ray lithography exposures in order to construct structures with photonic band gaps in the infrared region. First polymethylmethacrylate (PMMA) resist layers with a thickness of 500 μm were irradiated, then the holes in the resist structure were filled with preceramic polymer and subsequent pyrolysis converts the preceramic polymer into a SiCN ceramic. Theoretical results with fitted values of the dielectric constant are in good agreement with the transmission measurements.We have developed a new microfabrication technique for the construction of three-dimensional photonic crystals. In particular, we used multiple tilted x-ray lithography exposures in order to construct structures with photonic band gaps in the infrared region. First polymethylmethacrylate (PMMA) resist layers with a thickness of 500 μm were irradiated, then the holes in the resist structure were filled with preceramic polymer and subsequent pyrolysis converts the preceramic polymer into a SiCN ceramic. Theoretical results with fitted values of the dielectric constant are in good agreement with the transmission measurements.
TL;DR: In this article, population inversion and sub-Poissonian excitation statistics of two-level atoms in the context of collective resonance fluorescence were demonstrated in the photonic band gap and other confined photonic systems.
Abstract: We demonstrate population inversion and sub-Poissonian excitation statistics of $N$ two-level atoms in the context of collective resonance fluorescence. This occurs within photonic band gap and other confined photonic systems that exhibit sharp features in the optical density of states. When the deviation in the photon density of states between the Mollow spectral components is considerable, the atoms switch collectively from ground to excited states at a critical value of the applied laser field. This suggests a new mechanism of sub-Poissonian pumping of lasers, fast optical switching, and optical transistor action.
TL;DR: In this paper, phase matched second harmonic generation is observed experimentally in a centrosymmetric crystalline lattice of dielectric spheres of optical dimensions, where the inversion symmetry is broken locally at the surface of each sphere in such a way that the scattered second harmonic light interferes constructively leading to a nonvanishing macroscopic field.
Abstract: Phase matched second harmonic generation is observed experimentally in a centrosymmetric crystalline lattice of dielectric spheres of optical dimensions. The inversion symmetry is broken locally at the surface of each sphere in such a way that the scattered second harmonic light interferes constructively leading to a nonvanishing macroscopic field. Phase matching of the fundamental and second harmonic waves in such periodic lattice is observed to be naturally provided by the bending of the photondispersion curve at the edge of the Bragg reflection band of a given set of lattice planes.
TL;DR: In this paper, a large enhancement of optical nonlinearity in one-dimensional photonic-crystal structures with a defect is considered theoretically, and it is shown that the enhancement can be obtained for absorption saturation and degenerate four-wave mixing efficiency as a result of large optical field amplitude of the localized photonic defect mode at the defect layer.
Abstract: Enhancement of optical nonlinearity in one-dimensional photonic-crystal structures with a defect is considered theoretically. It is shown that a large enhancement can be obtained for absorption saturation and degenerate four-wave mixing efficiency as a result of large optical field amplitude of the localized photonic-defect mode at the defect layer. The figure of merit of the use of the photonic-crystal structure is derived especially for systems in which the concentration of the nonlinear optical material can be arbitrarily adjusted. Optical bistability is also predicted for optically dense samples. They can be applied in real photonic devices because of their simple structure and the large enhancement obtained.
02 Dec 1997
TL;DR: In this article, the first comprehensive investigation of synthesized dielectric materials which possess distinctive stopbands for microstrip lines was performed using FDTD, and four types of these photonic band-gap (PBG) structures have been simulated with FDTD.
Abstract: We report the first comprehensive investigation of synthesized dielectric materials which possess distinctive stopbands for microstrip lines. Four types of these photonic band-gap (PBG) structures have been simulated using FDTD. Experiment with a honeycomb-lattice PBG line shows excellent agreement between theoretical prediction and measurement.
TL;DR: In this paper, a large number of Bragg peaks of photonic colloidal single crystals were resolved by synchrotron small angle X-ray scattering (SAXS).
Abstract: We have resolved a great number of Bragg peaks of photonic colloidal single crystals by synchrotron small angle X-ray scattering (SAXS). We find that charge-stabilized colloids form face-centered cubic crystals at all densities up to ∼60 vol %. The colloidal particles are highly ordered on their lattice sites, which confirms that these self-organizing materials are suitable building blocks for optical photonic matter. The experiments demonstrate that synchrotron SAXS with two-dimensional detection is a powerful tool to study systems with length scales comparable to optical wavelengths.
Patent•
30 Oct 1997
TL;DR: In this paper, the use of photonic crystals to form optical elements which function in optical apparatus in frequency ranges outside photonic band-gaps is described, and a variety of optical apparatus including spectrometers, radiation sources, and lasers are enabled by such optical elements.
Abstract: The present invention describes the use of photonic crystals to form optical elements which function in optical apparatus in frequency ranges outside photonic band-gaps. Such optical elements may apply such optical properties as dispersion, anisotropy, and birefringence (all of which are exhibited by photonic crystals outside photonic band-gaps). A variety of optical apparatus, including spectrometers, radiation sources, and lasers are enabled by such optical elements.
TL;DR: In this article, anisotropic etching and steam oxidation of AlAs mask layers are used for the fabrication of high quality two-dimensional and three-dimensional (3D) photonic crystals.
Abstract: We have developed new methods for the fabrication of high quality two-dimensional (2D) and three-dimensional (3D) photonic crystals. These techniques involve anisotropic etching and steam oxidation of AlAs mask layers. We have made manufacturable 2D photonic crystals with high aspect ratios for use as micropolarizers and have measured extinction ratios larger than 800 to 1 between TE and TM modes transmitted through these structures. The new Al2O3 mask fabrication technique also allows us to fabricate 3D structures with up to six repeating layers in depth and over 90% attenuation in the band gap region. Here, we show the fabrication details and performance of 2D and 3D photonic crystals.
TL;DR: In this article, the resonant dipole-dipole interaction (RDDI) is strongly modified for atomic transition frequencies in the vicinity of the band-gap edge, but an analytical approximation to the RDDI is obtained by numerical integration using the exact dispersion relation, and the amplitudes for the two atoms without resorting to the pole approximation which is necessary due to the strongly modified mode structure in the dielectric host.
Abstract: We extend recent work on two closely spaced atoms interacting through the narrow band of strongly coupled modes at the edge of a photonic band gap. The resonant dipole-dipole interaction (RDDI) is strongly modified for atomic transition frequencies in the vicinity of the band-gap edge, but we show that an analytical approximation to the RDDI agrees very well with the exact RDDI obtained by numerical integration using the exact dispersion relation. Having established the value of the RDDI, we can derive the amplitudes for the two atoms without resorting to the pole approximation which is necessary due to the strongly modified mode structure in the dielectric host. For a wide range of parameters we find beating and population trapping in the long time limit. The distribution of population in the photonic continuum is investigated in the long time limit in the case of one and two atoms. It is found to be strongly asymmetric and to exhibit a strong signature of the unusual mode structure in the material at the band-gap edge.
TL;DR: In this paper, a high-pass structure with a cutoff frequency of 3 THz and attenuation of more than 35 dB in the cutoff region is presented, in good agreement with predicted results.
Abstract: Metallic photonic band gap (MPBG) filter structures operating at far infrared wavelengths have been designed, fabricated, and characterized. The MPBGs are multilayer metallic meshes imbedded in a flexible polyimide dielectric. Depending on the periodic pattern of the metal grids, the filters have either simple high-pass or more complex transmission characteristics. The critical frequencies of the filters depend on the spatial periodicity of the metal grids and the interlayer separation. Optical transmission measurements on a high-pass structure show cutoff frequency of 3 THz and attenuation of more than 35 dB in the cutoff region, in good agreement with predicted results. Band-reject filters show similarly good attenuation and large fractional bandwidths. The filters maintain their optical characteristics after repeated bending, demonstrating mechanical robustness of the MPBG structure.
TL;DR: In this paper, the optical properties of two-dimensional photonic crystals combined with a waveguide geometry, and etched into a light-emitting (GaAs/InGaAs) semiconductor are assessed.
Abstract: We describe an experimental setup, which allows assessing the optical properties of two-dimensional photonic crystals combined with a waveguide geometry, and etched into a light-emitting (GaAs/InGaAs) semiconductor By means of a guiding layer, the spontaneous emission of the material is used as a built-in source to probe the properties of the etched microstructure, conveniently compared to the usual measurement schemes We show polarized transmission and coefficients largely depending on the photonic crystal orientation
TL;DR: In this article, a waveguide based microcavity exhibiting a quality factor Q/spl ap/2500 has been realized by incorporating a /spl lambda/4 phase shift into a 1-D photonic microstructure.
Abstract: A waveguide based microcavity exhibiting a quality factor Q/spl ap/2500 has been realized by incorporating a /spl lambda//4 phase shift into a 1-D photonic microstructure. The microstructure has an overall length of 3 /spl mu/m, consists of a deeply etched grating with very narrow (75 nm) air-gaps and exhibits a third-order stop band in the 800-900 nm wavelength regime. A comparison between measurement and simulation suggests that there is a thin (approximately 18 nm) skin of oxidized material at the etched semiconductor-air interfaces.