Extreme narrow photonic bands and strong photonic localization produced by 2D defect two-segment-connected quadrangular waveguide networks

In this paper, we investigate the properties of optical transmission and photonic localization of two-dimensional (2D) defect two-segment-connected quadrangular waveguide networks (DTSCQWNs) and find that many groups of extreme narrow photonic bands are created in the middle of the transmission spectra. The electromagnetic (EM) waves in DTSCQWNs with the frequencies of extreme narrow photonic bands can produce strong photonic localizations by adjusting defect broken degree. On the other hand, we obtain the formula of extreme narrow photonic bands’ frequencies dependent on defect broken degree and the formula of the largest intensity of photonic localization dependent on defect broken degree, respectively. It may possess potential application for designing all-optical devices based on strong photonic localizations. Additionally, we propose a so-called defecton mode to study the splitting rules of extreme narrow photonic bands, where decomposition-decimation method is expanded from the field of electronic energy spectra to that of optical transmission spectra.     

Conversion of short-wavelength electromagnetic radiation in SiO2 opal photonic crystals

Reflection spectra of the (111) growth surface of opal photonic crystals differing in silica sphere diameter have been measured under illumination with narrowband ultraviolet and violet light from a laser and light-emitting diodes and with broadband light from a halogen lamp. We have found narrow strong bands differing in spectral position from the light from the short-wavelength excitation sources. The spectral position of these bands corresponds to that of photonic band gaps and is independent of excitation wavelength. The silica sphere diameter has no effect on the shape of the reflection band, and its position always correlates with that of the band gap of the opal. The present results demonstrate that exposure of a photonic crystal to short-wavelength radiation leads to conversion of the radiation to the spectral range of the band gap. The microscopic mechanism of the conversion process may involve three-photon parametric processes and amplification of the broadband photoluminescence due to structural defects in the silica matrix. Our results open up the possibility of creating new types of optically pumped solid gain media based on opal photonic crystals.     

Photonic bandgaps of different unit cells in the basic structural unit of germanium-based two-dimensional decagonal photonic quasi-crystals

Based on the infrared optical material germanium, in the basic structural unit of a two-dimensional decagonal photonic quasi-crystal, photonic bandgaps of four square unit cells with a scattering radius in the range of [0,0.3a] have been calculated within two cases of construction (i.e., air cylinders arranged in germanium and germanium cylinders arranged in air) by using the plane wave expansion method. In considering the Bragg-like scattering effect in two-dimensional photonic quasi-crystals as the elastic collision in physics, we put forward the photonic bandgap impact function F=q(1)q(2)q(3)επr(2) for the first time, to the best of our knowledge. A certain unit cell structure shares some similar photonic bandgap properties with a periodic structure. For a certain structure of the unit cell, the center frequency change trends of the photonic bandgap and the type of photonic bandgap generated are not related with the period of the photonic crystal, but with the relative dielectric constant and the construction, respectively. Different unit cell structures own different photonic bandgap structures. This occurs because the high degree of rotational symmetry of the quasi-periodic structure and weak long-range order of the basic structural unit lead to different Bragg-like scattering effects within the unit cell structures.     

Properties of defect modes in geometrically chirped one-dimensional photonic crystals

The variation of the transmission coefficient with defect mode frequency in a geometrically chirped photonic crystal with central defect layer has been investigated theoretically using transfer matrix method and validated experimentally by fabricating and characterizing such photonic crystals. The defect mode frequency is extracted by modeling the defect layer as a Fabry-Perot resonant cavity with mirrors replaced by two geometrically chirped photonic crystals. It is shown that the structural asymmetry of the chirped photonic crystals with respect to the central defect layer affects the width of the photonic band gap and also induces coupling variation between the eigenmodes of the defect layer and those at the band edges of the constituent photonic crystals. This leads to variation in the defect mode transmittance across the photonic band gap and introduces notches at positions where the eigenmodes of the band edges have maximum transmission.     

Electromagnetic phenomenological study of photonic band structures

Abstract

It is shown, in the case of one-dimensional photonic crystals, that the transmission gaps are caused by the existence of resonance phenomena inside the layers which constitute the crystal. From a mathematical point of view, these resonances are associated with poles and zeros in the complex plane of the wavenumber k. Transmission gaps are located outside these resonance regions. A phenomenological formula allows us to represent quantitatively the transmission inside the gaps. Finally, a synthetic explanation of the properties of doped and non-doped crystals is proposed and it is shown that the transmission peaks inside the gaps of doped photonic crystals are caused by a shift of poles and zeros located inside the resonance regions of non-doped crystals.     

Hybrid colloidal plasmonic-photonic crystals

We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals.     

Negative refraction in the visible range in water-infiltrated opal photonic crystals

A negative refraction effect has been found in opal photonic crystals in the visible range. We have calculated the dispersion branches of a photonic crystal and determined the position of its photonic band gap. The frequency range has been identified where the refractive index of the opal is negative. An experimental arrangement is proposed for focusing a light beam by passing it through a plane-parallel opal photonic crystal and experimental evidence is presented in favor of negative refraction in the visible range.     

Mode tuning in dispersive and non-dispersive photonic crystals by defects

Transmission spectrum of two-dimensional photonic crystal for dispersive and non-dispersive photonic crystals (PhC) is calculated. Calculations show that by considering defect electromagnetic waves can propagate in PhC band gap. Transmission spectrum for different types of defects is compared together. The number and position of transmission modes in PhC waveguide depend on host PhC and type of defects. By selecting suitable PhC material and defect type, the number and position of transmission modes can be controlled.     

光子晶体应用研究进展

光子晶体是一种具有光子带隙的新型材料,其概念提出比较早,距今已经过了30年。由于光子晶体具有很多新颖的特性,使其成为微纳光子学和量子光学的重要研究领域。随着微加工技术的进步和理论的深入研究,光子晶体在信息光学以及多功能传感器等其他多个学科中也得到广泛应用。本文从理论上详细综述了光子晶体的各种奇异特性,并从各种特性出发,详细介绍近年来光子晶体在光子晶体光纤、反射镜、滤波器、波导、低阈值激光器、多功能传感器、腔量子电动力学、偏振器、量子信息处理等领域的应用研究,并与传统的器件进行性能比较得出光子晶体器件具有无可比拟的优势。最后提出,随着3D打印制造技术的成熟,光子晶体材料必然会推动信息技术的新一轮革命。     

Microassembly of semiconductor three-dimensional photonic crystals

Electronic devices and their highly integrated components formed from semiconductor crystals contain complex three-dimensional (3D) arrangements of elements and wiring. Photonic crystals, being analogous to semiconductor crystals, are expected to require a 3D structure to form successful optoelectronic devices. Here, we report a novel fabrication technology for a semiconductor 3D photonic crystal by uniting integrated circuit processing technology with micromanipulation. Four- to twenty-layered (five periods) crystals, including one with a controlled defect, for infrared wavelengths of 3-4.5 microm, were integrated at predetermined positions on a chip (structural error <50 nm). Numerical calculations revealed that a transmission peak observed at the upper frequency edge of the bandgap originated from the excitation of a resonant guided mode in the defective layers. Despite their importance, detailed discussions on the defective modes of 3D photonic crystals for such short wavelengths have not been reported before. This technology offers great potential for the production of optical wavelength photonic crystal devices.     

Theoretical studies on transforming a GaN semiconductor into a photonic crystal under a periodic external magnetic field

In this study, the properties of light propagation for a GaN semiconductor when subjected to a periodic external magnetic field were calculated by means of a transfer matrix. The dielectric function which was modulated periodically by the periodic external magnetic field caused changes of photonic band gap (PBG). In the reflection spectra, photons can be localized in the narrow bands. The position and intensity of PBGs can be modulated by changing the periodic external magnetic field and angle of the incident electromagnetic wave. All of these results have shown that a semiconductor has functions similar to conventional photonic crystals subjected to periodic external magnetic field.     

Experimental observation of photonic and polaritonic gaps in a silica opal

Experimental observations of the simultaneous presence of a polaritonic and a photonic gap in a three-dimensional photonic crystal is reported, to the best of our knowledge, for the first time. The photonic crystal was made of monodispersed silica microspheres sedimented into a face-centered-cubic structure. Silica has a polaritonic gap for wavelengths between 8 and 9.35 microm. Four different sphere sizes were used, with diameters of d=0.49, 0.73, 0.99, and 1.57 microm. The photonic crystals were studied by normal incidence infrared reflectance measurements in the wavelength interval 0.8-12 microm. Four peaks with the a magnitude of approximately 0.6, originating from the periodicity of the crystal, were recorded in the interval between 1 and 4 microm. Another peak, the polaritonic reflectance peak (approximately 0.4), is observed for wavelengths around 9 microm for all four crystals.     

Fano-Like Resonance from Disorder Correlation in Vacancy-Doped Photonic Crystals

By preparing colloidal crystals with random missing scatterers, crystals are created where disorder is embodied as vacancies in an otherwise perfect lattice. In this special system, there is a critical defect concentration where light propagation undergoes a transition from an all but perfect reflector (for the spectral range defined by the Bragg condition), to a metamaterial exhibiting an enhanced transmission phenomenon. It is shown that this behavior can be phenomenologically described in terms of Fano-like resonances. The results show that the Fano's parameter q experiences a sign change signaling the transition from a perfect crystal exhibiting a reflectance Bragg peak, through a state where background scattering is maximum and Bragg reflectance reaches a minimum to a point where the system reenters a low scattering state recovering ordinary Bragg diffraction. A simple dipolar model considering the correlation between scatterers and vacancies is proposed and the reported evolution of the Fano-like scattering is explained in terms of the emerging covariance between the optical paths and polarizabilities and the effect of field enhancement in photonic crystal (PhC) defects.     

Improvement of spectral efficiency based on spectral splitting in photonic quantum-well structures

The multiple photonic quantum-well structures are proposed by breaking the periodicity of a one-dimensional photonic crystal, in which the effect of spectral splitting is clearly observed. On the basis of the finite-difference time-domain method, the physical origin of the spectral splitting is explained, and the regularity of the formation of the multiple peaks is analysed. It is also found that both the well and barrier thicknesses have a marked influence on the positions and the number of the split peaks, and their relationships are carefully discussed. By using these proposed structures, the number of transmission peaks can be increased multiplicatively, and their spectral spacing can be finely tuned, resulting in high efficient utilisation of photonic band gap.     

一维杆状声子晶体的带隙特性

用有限元方法计算了一维杆状声子晶体的振动传输特性及其振动模态,从振形角度分析了一维杆状声子晶体相关参数(物理参数、尺寸参数)对带隙起始频率及带隙宽度的影响,发现带隙的形成与其模态振形密切相关,各参数对声子晶体带隙的影响主要是影响了个模态所在的频率,从而改变了其带隙的起始位置及宽度。     

LED-excited emission of opal infiltrated with ferroelectrics and phosphors

We have measured emission spectra of opal photonic crystals infiltrated with ferroelectrics and phosphors. At a given excitation wavelength, the emission spectra of the infiltrated opals differ markedly from the spectrum of plain opal: the emission bands are redshifted, and extra peaks are present. The infiltration effect on the emission spectrum of the opal matrix can be accounted for by the shift of the photonic band gap.     

Position-dependent absorption-dispersion spectrum of a Λ-type three-level atom embedded in a defective photonic crystal

The position-dependent optical spectra of a Λ-type three-level atom embedded in a photonic crystal are studied by considering the double-band photonic band gap reservoir with defect modes in the band gap. It is shown that the number of absorption peaks, transparency windows and the slope of the dispersion curve can be modulated by adjusting the position of the embedded atom.     

Raman scattering study of NaNO2-infiltrated opal photonic crystals

We have studied light scattering in synthetic opal crystals infiltrated with ferroelectric sodium nitrite, NaNO₂, and have analyzed simple models for the energy band structure of photonic crystals. Expressions have been derived for the group velocity of photons whose energy is close to the photonic band gap. Our results indicate that the infiltration of photonic crystals with NaNO₂ markedly increases the Raman scattering intensity.     

Luminescent properties of synthetic opal

We have studied the effect of the photonic band gap on the visible luminescence of opal photonic crystals. The results indicate that the position of the photonic band gap in the luminescence and reflection spectra of opal depends on the photon propagation direction. Optical measurements have been used to determine the refractive index of opal and the diameter of silica spheres. We have assessed the effect of oxygen annealing on the intrinsic luminescence spectra and crystal structure of opal. The emission centers in synthetic opal have been tentatively identified. The visible luminescence intensity in opal is shown to be anisotropic, in accordance with the frequency and angular dispersions of the first photonic band gap in opal. Original Russian Text ? A.N. Gruzintsev, G.A. Emel’chenko, V.M. Masalov, M. Romanelli, C. Barthou, P. Benalloul, A. Ma?tre, 2008, published in Neorganicheskie Materialy, 2008, Vol. 44, No. 2, pp. 203–209.     

三维光子晶体及其制备技术研究进展

光子晶体是一种新概念人工结构功能材料,通过设计可以人为调控经典波的传榆.而三维光子晶体能产生全方向的完全禁带,具有更普遍的实用性.从结构、材料及应用探索3方面介绍了近几年来光学波段三维光子晶体的最新发展动向:以器件化为指导,逐步由简单媒质简单周期向复杂媒质复合周期结构方向发展,由胶体模板自组装等纯化学制备手段向物理化学方法相融合的多元技术扩展,其应用领域也由光电子器件、集成光路进一步拓展到光电对抗、光学探测、传感等.