1D PC Research Articles

Highly efficient all-optical diode action based on light-tunneling heterostructures

We theoretically investigate the feasibility of constructing compact and highly efficient all-optical diodes (AODs) based on light tunneling mechanism in heterostructures. Due to light tunneling behaviors in heterostructures with one-dimensional photonic crystals (1D PC) and lossy metallic film, not only very large nonlinear permittivity of metal can be utilized sufficiently but also the structures with strongly nonreciprocal electric field distributions can be constructed. Finally we design a composite structure consisting of 1D PC-metal heterostructures to achieve the optimal unidirectional light transmission with 0.984 transmission contrasts, 42% transmission and 0.93 GW/cm(2) operating light power at working wavelength 557.2nm.

Optical properties of one-dimensional photonic crystals fabricated by photo-electrochemical etching of silicon

The optical properties of one-dimensional photonic crystals (1D PCs), fabricated by electrochemical etching of periodic wall arrays on n-type (100) Si substrates, are investigated in this study. Several 1D PCs were fabricated with lattice periods varying from 4 to 7 μm and with trench depths in the range 160–210 μm. In-plane reflection spectra of the photonic structures at different depths were registered over a wide spectral range of 1.5–15 μm using Fourier Transform Infra-Red (FTIR) micro-spectroscopy. Some of the features observed in the reflection spectra of the structures investigated are believed to be as a result of interface roughness. A corrugated side-wall surface, an artifact of the fabrication technique, results in the degradation of optical reflection characteristics, principally mainly in the near IR spectral range, and the emergence of optical anisotropy. As a result of the periodicity, modulation of the reflection spectra, that is, the difference between the maxima and minima of the interference fringes, reached a value of 95% in the mid-infrared. The optical properties of the structures investigated indicate that they show promise for microphotonics applications.

Characteristics of spontaneous emission in confined one-dimensional photonic crystals

We present a type of confined one-dimensional photonic crystal (1D PC) that is composed of a 1D PC confined by perfect conductor boundaries in the lateral directions of the 1D PC. The dispersion relations are derived using the classical electromagnetic approach, and the photonic density of states and local photonic density of states are calculated numerically. It is found that the combined action of the periodic modulation and the quantization of wave vectors in the lateral directions may give rise to photonic bandgaps and sharp peaks in the photonic density of states, which provides us with an effective way to control the spontaneous emission (SE). Based on this, the SE is investigated by the lifetime distribution function. The numerical results show that there is a wide lifetime distribution with the coexistence of accelerated and inhibited decay processes of the SE.

Modeling of amplification and light generation in one-dimensional photonic crystal using a multiwavelength transfer matrix approach

We present an analysis of amplification and lasing in one-dimensional isotropic nonlinear photonic crystal (1D PC), which is based on a generalized (multiwavelength) transfer matrix method. This approach was used for modeling a Raman signal amplification in 1D PC and in an homogenous structure, showing advantages of a stratified medium. Moreover, the threshold operation of a 1D PC Raman laser is studied, assuming both strong as well as depleted pump. The normalized threshold gain characteristics for various end reflections and photonic crystal laser length were calculated.

Analysis of Novel Building Blocks for Photonic MEMS Based on Deep 1D Photonic Crystals

This papers deals with the study of novel building blocks suitable for architectures of MEMS tunable lasers integrated in SOI platforms. These building blocks are based on the use of 1D photonic crystals (1D PCs) made of silicon-air thin layers stacks. These provide high reflectivity in certain wavelength range as well as access to simple Fabry-Perot cavities. The latter was studied more in detail and simulations are presented along with preliminary experimental results. A tilted Fabry-Perot cavity was analyzed for its potential of mode selector to prevent for mode hopping and thus enable continuous mode tuning by control of separation gap. As 1D PCs exhibit dispersion characteristics, this behavior is analyzed as well for its potential use for compensation purposes of wavelength dependence of the refractive index in the III-V gain medium.

Quantum interference between two orthogonal transitions of an atom in one-dimensional photonic crystals

We find that the V-type three-level Zeeman atom has the complete quantum interference when it is embedded in one-dimensional photonic crystals (1D PCs) possessing the TM-polarized complete gap. To avoid the nonradiative decay related to dissipation and the decay through surface exciton, we add two phase compensators made of ideal left-handed materials on two sides of atom, and then the total structure is equivalent to a 1D PC supporting only the radiative modes. The parameter regions (epsilon, mu) leading to the TM-polarized complete gap have been sketched out, and the influence of absorption on the quantum interference is discussed.

Complete photonic bandgaps for all polarizations in one-dimensional photonic crystals

The photonic band structures of one-dimensional photonic crystals (1D PCs) with threelayers in a period are studied theoretically. Our results show that complete photonicbandgaps (PBGs) for all polarizations can be obtained in these 1D PCs made of aconventional dielectric material, a negative-permittivity and a negative-permeabilitymetamaterial. The origin of the complete PBGs lies in the existence of surface waves for allpolarizations.

One Dimensional Polymeric Organic Photonic Crystals for DFB Lasers

We present a very simple method to realize a one-dimensional photonic crystal (1D PC), consisting of a dye-doped polymeric multilayer. Due to the high photonic density of states at the edges of the photonic band-gap (PBG), a surface emitting distributed feedback (DFB) laser is obtained with this structure. Furthermore, the incidence angle dependence of the PBG of the polymeric multilayer is reported.

Polarization-independent omnidirectional defect modes in Bragg gaps of one-dimensional photonic crystals

To minimize the dispersion of defect modes in the Bragg gap of a conventional one-dimensional photonic crystal (1D PC) doped with a defect layer of left-handed material (LHM), a numerical technique is developed for tuning the optimized parameters of the defect. Through a defect couple comprising a pair of adjacent right-handed material and LHM defect layers, omnidirectional defect modes (ODMs), within a determined tolerance limit, are generated and shown to be much less dispersive than some recently reported near-zero dispersion defect modes. A defect couple with a dispersive LHM yields multiple near-zero dispersion channels in the bandgap. We propose the defect-couple 1D PC as a design for generating polarization-independent ODMs.

Some new band gaps and defect modes of 1D photonic crystals composed of metamaterials

Some new band gaps are found in 1D photonic crystals (1D PC) composed of metamaterials (including negative- μ materials, negative- ε materials and negative refractive index materials). These band gaps are investigated by using the transfer matrix method. The properties (central frequency and width of the gap) of these new gaps are invariant with the scaling of the lattice constant and show weak dependence with the incident angles. These new gaps result from the dispersive properties of the metamaterials. A defect mode appears inside these new gaps upon the introduction of a defect layer. The spectral position of the defect mode is invariant upon the change of scale length and almost independent of incident angles.

Laser action and gain and attenuation properties of the 1D photonic crystal structure with active and passive layers

We present the results of calculations of the spectral characteristics of finite length 1D PC with air–glass-doped layers. For these calculations we used the transfer matrix formalism. The results of calculations of laser power are presented on the dependence from gain.

Realization of ultrawide omnidirectional photonic band gap in multiple one-dimensional photonic crystals

Theoretical and experimental investigations have shown that the omnidirectional photonic band gap (omni-PBG) of one-dimensional photonic crystals (1D PCs) can be enlarged by including multiple-periodic structures. These structures, consisting of Si–SiO2 alternating layers with multiple periods, Λ1, Λ2,…,ΛM, have great potential for ultrawide omnireflectors operating in the infrared frequency range. To confirm the effect of multiple periods in the 1D PCs, we prepared two types of 16-pair, Si∕SiO2 1D PCs with a single period of Λ1=426.9nm and Λ2=306.9nm, and one type of 16-pair 1D PC with double periods—the combination of eight-pair Λ1 and eight-pair Λ2. Theoretically, the normalized frequency range for omni-PBG (Δω) in double PC is enhanced by approximately twice that in the single PC. That is, Δω increases from 0.086 to 0.166, which corresponds to the wavelength range (Δλ) from 520to980nm for Λ=407.7nm. Measured reflectance (R) spectra are in a good agreement with the calculated results. For example, the R spectrum of Si∕SiO2 double 1D PC (8-pair Λ1+8-pair Λ2: Λ1=426.9nm, Λ2=306.9nm, and filling factor η=0.406) exhibits an ultrawide PBG over the wavelength range of 1050–2500nm for TE polarization at the incident angle of 5°.

Enhanced Light Output in InGaN-Based Light-Emitting Diodes with Omnidirectional One-Dimensional Photonic Crystals

We have successfully designed and fabricated GaN-based light-emitting diodes (LEDs) containing an omnidirectional one-dimensional photonic crystal (1D PC). The 1D PC is composed of alternatively stacked TiO2 and SiO2 layers designed to possess a photonic band gap (PBG) within the blue regime of interest. With the same multiple quantum well (MQW) emission peak at approximately 450 nm and a driving current of 20 mA, the light output powers of the LED with and without the 1D PC are approximately 11.7 and 6.5 mW, respectively. The enhancement in light extraction of our LED with 1D PC demonstrates that a properly designed omnidirectional 1D PC can have a higher reflectance and a wider reflection angle than a conventional distributed Bragg reflector (DBR). Our work shows promising potential for the enhancement of output powers of commercial light emitting devices.

Observation of two-photon absorption enhancement at double defect modes in one-dimensional photonic crystals

One-dimensional photonic crystals (1D PC) with two CdS defect layers in a SiO2∕TiO2 dielectric thin film stack were fabricated. Two-photon absorption (TPA) coefficients of the CdS defect layers in the 1D PC were investigated using femtosecond pump-probe method. Significant enhancement of the TPA coefficient in the CdS defect layers was observed to occur at the two defect modes. Experimental results show that the enhanced TPA coefficient at the defect mode of 800nm is larger than that at the defect mode of 762nm. A numerical simulation by matrix transfer method is performed and agrees with the experimental results very well.

Superprism effect in 1D photonic crystal

It is shown that superprism effect can be observed not only in 2D and 3D photonic crystal but also in 1D photonic crystal. To observe the effect a diffraction grating should be put on the top of the 1D PC. It is shown that the band gap more dramatically appears in 1D PC than in 2D PC. This effect makes all PBG effects including superprism effect more pronounced and also weakens the influence of losses.

Dispersive medium’s normal coupled modes and low threshold optical bistability in a symmetric one-dimensional photonic crystal

We present a detailed study of the dispersive medium’s normal coupled modes in a symmetric one-dimensional photonic crystals (1D PCs). The splitting, homogeneous broadening effect, and the detuning effect of the normal coupled modes can be well controlled by adjusting the parameters of the dispersive medium. The bistable behavior of the PCs with Kerr medium is also investigated and it is found that the threshold intensity of nonlinear optical bistability (OB) of 1D PCs with dispersive medium is much lower than that of structure without dispersive medium. The threshold intensity is strikingly sensitive to the coupling strength of the dispersive medium.

Internal high-reflectivity omni-directional reflectors

An internal high-reflectivity omni-directional reflector (ODR) for the visible spectrum is realized by the combination of total internal reflection using a low-refractive-index (low-n) material and reflection from a one-dimensional photonic crystal (1D PC). The low-n layer limits the range of angles in the 1D PC to values below the Brewster angle, thereby enabling high reflectivity and omni-directionality. This ODR is demonstrated using GaP as ambient, nanoporous SiO2 with a very low refractive index (n=1.10), and a four-pair TiO2/SiO2 multilayer stack. The results indicate a two orders of magnitude lower angle-integrated transverse-electric-transverse-magnetic polarization averaged mirror loss of the ODR compared with conventional distributed Bragg reflectors and metal reflectors. This indicates the high potential of the internal ODRs for optoelectronic semiconductor devices, e.g., light-emitting diodes.

Tunable and omnidirectional photonic bandgap properties of one-dimensional photonic crystals fabricated by holography

We carried out a theoretical investigation on photonic bandgap (PBG) properties of one-dimensional photonic crystals (1D PCs) constructed by our periodically doping metal or semiconductor nanoparticles into polymers with a holographic interference technique. The results reveal not only that both the bandgap width and the midwavelength of the PBG are tunable by the choice of parameters of recording materials and exposure conditions but also that 1D PCs may show an omnidirectional PBG property if the doped nanoparticles are from a higher-refractive-index semiconductor material. Some realistic factors, such as the absorption (in the case of the doped nanoparticles that are from a metallic material) and instability of the holographic recording setup during the exposure process, are also theoretically demonstrated to have no serious bad effect on PBG properties of the 1D PCs fabricated by the method. Our conclusions may open up a robust way for one-step fabrications of three-dimensional PCs, omnidirectional 1D PCs, and other photonic devices by cheap, repeatable, and efficient holography.

Design and evaluation of omnidirectional one-dimensional photonic crystals

We have theoretically and experimentally studied a wide range of realistic fabrication parameters for the formation of omnidirectional photonic band gaps (PBGs) in one-dimensional photonic crystals (1D PCs). Photonic band structures in 1D PCs have been analyzed for the cases with and without a defect layer. It is shown that a defect state in the defect-mode PBG behaves like an electronic impurity level in the gap with a change in thickness (i.e., optical path) of the defect layer. Three types of 1D PC structures (Te/polystyrene, Si/SiO2, and ZnS/SiO2), which are designed for applications in the infrared region (especially for the wavelength of 1.55 μm) and in the visible region, are proposed and demonstrated their high reflectance (R) properties experimentally. For example, a six-pair Si/SiO2 1D PC fabricated with a structure parameter (period=388.5 nm, filling factor=0.406) exhibits a wide range omni-PBGs in the wavelength range of 1310–1742 nm. The measured R spectra are in very good agreement with calculated results. In particular, the R spectra of a ZnS/SiO2 1D PC in the wavelength range of 190–800 nm are almost the same as those calculated using complex refractive indices. We also propose conditions to obtain omni-PBGs and band structures for a high refractive-index ambient medium (n).

Si-based omnidirectional reflector and transmission filter optimized at a wavelength of 1.55 μm

Omnidirectional (omni-) reflector and transmission filter optimized at a wavelength of 1.55 μm have been realized using Si/SiO2 one-dimensional photonic crystals (1D PCs). Photonic band structures in the PCs with and without a defect layer have been also analyzed. The 1D PCs fabricated have very large omnidirectional photonic band gaps (omni-PBGs), and their measured reflectance spectra are in very good agreement with the calculated results. The omni-PBG in a six-pair Si/SiO2 1D PC (no defect layer, a filling factor η=0.406) exists in a normalized frequency range of 0.223–0.297. Introducing a defect layer generates a defect state in the PBG, and it behaves like electronic impurity levels in the gap with a change in thickness of the defect layer (dD). A six-pair Si/SiO2 1D PC with the structure parameters of η=4.060, dH (Si thickness)=95.3 nm, dL (SiO2 thickness)=234.9 nm, and dD=2.336⋅dH could act as a 1.55 μm-transmission filter for normal incidence light.