Defect Modes In Photonic Crystals Research Articles

Investigation of non-reciprocity and behavior of defect modes in photonic crystals incorporating Weyl semimetals

Abstract The ability to control the frequency of defect modes in photonic crystals has led to the emergence of novel applications. Researchers have recognized the unique properties of Weyl semimetals and explored their utilization in photonic crystals. This study investigates the non-reciprocal properties in photonic crystals incorporating Weyl semimetals and examines the behavior of defect modes within these crystals. This paper employs a photonic crystal containing Weyl semimetals with two different structures. Initially, the non-reciprocal properties in both structures are examined, followed by an analysis of the behavior of defect modes. The results indicate that only utilizing Weyl semimetal in the photonic crystal does not result in non-reciprocity. The arrangement of layers next to each other, or the geometry, plays a crucial role in non-reciprocity. Additionally, the behavior of defect modes varies depending on the structure type and propagation direction.

Multiple nonreciprocal transmission based on defect modes of photonic crystals

Multiple nonreciprocal transmission based on defect modes of photonic crystals

Wide-angle polarization selectivity based on anomalous defect mode in photonic crystal containing hyperbolic metamaterials.

Conventional defect modes in all-dielectric 1D photonic crystals (PCs) are polarization-insensitive. This poses a great challenge in achieving high-performance polarization selectivity. In this Letter, we introduce a defect layer into a 1D PC containing hyperbolic metamaterials to achieve an anomalous defect mode with polarization-sensitive characteristics. As the incident angle increases, such a defect mode remains almost unshifted under transverse magnetic polarization, while strongly shifting toward shorter wavelengths under transverse electric polarization. The polarization-sensitive characteristics of the defect mode can be well explained by the Fabry-Perot resonance condition. Assisted by the polarization-sensitive defect mode, wide-angle polarization selectivity with an operating angle width up to 54.8° can be realized. Our work provides a route to designing wide-angle linear polarizers using simple 1D structures, which would be useful in liquid crystal display and Q-switched lasers.

Magneto-optical effects on the properties of the photonic spin Hall effect owing to the defect mode in photonic crystals with plasma

In this study, we have demonstrated a multi-layered structure to examine how the magneto-optical effects affect the behavior of the photonic spin Hall effect (PSHE). The Faraday and Voigt effects are taken into account. The multi-layered structure is one-dimensional (1D) photonic crystal (PC) with a defective plasma layer. The properties of the PSHE in both symmetric and asymmetric defective PCs are explored. The numerical results show that the applied magnetic field and the geometries of the structures have significantly changed the characteristics of the PSHE. The transverse displacements of the H-polarization can be easily enhanced by more than ten times, while the transverse displacement of the V-polarization can be easily suppressed by a few percent based the manipulating of the external magnetic field. Moreover, the magneto-optical effects can change the optimal incident angle for the assessment of the peak transverse displacements of the PSHE. In addition, the numerical results also show that the plasma frequency, defective plasma thickness, and the geometry of the structure have greatly influenced the behavior of the PSHE. The parameter dependencies of theses effects are also calculated and discussed.

Enhancement and modulation of photonic spin Hall effect by defect modes in photonic crystals with graphene

Photonic spin Hall effect (PSHE) holds great potential applications for manipulating photon spins. However, the efficient control of PSHE in a particular optical structure is still difficult to realize. In this paper, we report enhanced and magnetically tunable PSHE of reflected light in one-dimensional photonic crystals (1D-PC) with a defect layer. By inserting monolayer graphene into the defect layer of 1D-PC, large polarization rotation and strong photon spin-orbit interaction of reflected light are obtained. Due to the optical field confinement by defect mode, the Kerr rotation angle of reflected light is near 90° and the spin-dependent splitting is about 15 times the wavelength at a specific incident wavelength. In addition, a static perpendicular magnetic field increasing from 1T to 11T shows greatly modulation effect on Kerr rotation angle and spin-dependent splitting. These results pave the way toward the design of spin-based photonic devices in the future.

Experimental realization of tunable defect mode in photonic crystal

Defect modes located at different position were prepared by introducing defect layers in the porous alumina based photonic crystals. Furthermore, experiments and simulations were carried out to investigate the properties of such defect modes. The results show that defect mode can be tuned easily by changing thickness and location of the defect layer, moreover, the optical properties of defect mode when changing the incident angle are also studied.

Magnet-controlled surface defect modes of photonic crystal

In order to obtain tunable surface modes of photonic crystal, we add a magnetic material layer on the truncated surface of a two-dimensional photonic crystal. Through calculations of photonic band, we obtain the surface defect modes in the first and second gaps. Through the modulation of applied magnetic field, we can control the frequency, the group velocity and the exciting incidence direction of the surface defect mode. In particular, in the frequency range of surface defect modes, we can tune the group velocity to zero.

Coherent perfect absorption in one-dimensional photonic crystal with a PT-symmetric defect

In this paper, we demonstrate a one-dimensional photonic crystal defect mode coherent perfect absorber (CPA) or antilasing, which is based on the PT-synthetic material defect. It is found that the CPA can be excited by two coherent monochromatic waves which are located at the frequency range of the defect mode (near the top of the transmission peak in the gap) incident with the same amplitude from both sides. Moreover, we found that the CPA frequency possesses the property of flexible controllability. This property can easily be realized by modulating the variation in thickness of the defect layer and the symmetrical incidence angle of the two coherent beams. Therefore, the photonic crystal defect mode CPA proposed here shows much more flexibility in operation frequency compared with the results in the literature (Chong Y. D. et al., Phys. Rev. Lett., 105 (2010) 053901; Wan W. et al., Science, 331 (2011) 889).

Influence of incident angle on the defect mode of locally doped photonic crystal

By means of a transfer matrix method, this paper deduces the transmittance calculation equation of light travelling in locally doped (including one defect layer) mirror heterostructure (ABCCBA)P D(ABCCBA)Q photonic crystals. In the cases of defect layers being either introduced or not introduced, an ORIGIN simulation shows the influence of incident angle change on the number of photon band gap, bandwidth and defect mode numbers. Studies indicate that when such photonic crystals have 8 mirror cycles and the thickness of defect layer D meets nDdD = λ0/2 or nDdD = 4λ0, the photonic crystal defect mode transmission peak changes significantly. Also, with the change of incident angle, the number of defect mode transmission peaks changes. By altering incident angle and defect layer thickness, we can get photon band gaps and defect mode transmission peaks at different frequency domains and different relative angular frequencies. This provides theoretical reference for achieving light wave multi-channel filtering and tunable filtering.

The Defect Modes Property Controlled by Temperature in One Dimensional Photonic Crystal with Liquid Crystal Defect Layer

The 5CB liquid crystal as defects will be introduced to one dimensional photonic crystal, taking advantage of temperature property of liquid crystal refractive index, the transmission spectrum of one dimensional liquid crystal defect photonic crystal defect modes was researched by the transfer matrix method(TMM). The numerical results indicated that when the temperature went up, one dimensional liquid crystal defect photonic crystal defect modes removed towards the long wavelength. When the temperature increased from 273k to 320k, the defect modes wavelength from 5121nm drifted to 5508nm, the wavelength shift was 387nm and the maximum of temperature sensitivity was 10.85nm/K, it was also observed that the temperature sensitivity decreased as the temperature increased.

Fano resonance and wave transmission through a chain structure with an isolated ring composed of defects

We consider a discrete model that describes a linear chain of particles coupled to an isolated ring composed of N defects. This simple system can be regarded as a generalization of the familiar Fano-Anderson model. It can be used to model discrete networks of coupled defect modes in photonic crystals and simple waveguide arrays in two-dimensional lattices. The analytical result of the transmission coefficient is obtained, along with the conditions for perfect reflections and transmissions due to either destructive or constructive interferences. Using a simple example, we further investigate the relationship between the resonant frequencies and the number of defects N, and study how to affect the numbers of perfect reflections and transmissions. In addition, we demonstrate how these resonance transmissions and refections can be tuned by one nonlinear defect of the network that possesses a nonlinear Kerr-like response.

Theoretical Investigation of Noise and Modulation Characteristics of Photonic Crystal Lasers

Theoretical analysis is presented to characterize the dynamics of electrically injected single-defect photonic crystal vertical-cavity surface-emitting lasers. The analysis is based on a phenomenological dimensional reduction approach for modeling the photonic crystal defect mode cavity and yields analytical expressions to characterize the noise and small-signal modulation response. The simulation results indicate that the photonic crystal laser has a lower noise level and high-frequency modulation response compared with a conventional counterpart.

光束非相干性对光子晶体缺陷模式透射位移的影响分析

光束非相干性对光子晶体缺陷模式透射位移的影响分析

Influence of defect mode displacement in photonic crystal band gap over light group velocity

The light group velocity of defect mode in photonic crystal is active controlled in order to gain controllable light delay by using thermo-optic effect to change the reflective index of material or changing the geometry structure of photonic crystal. From former research we know that the position of defect mode in band gap is changed with light group velocity. Our research further finds that the position of defect mode can be kept by changing more than one parameter correspondingly, and meanwhile the group velocity is not changed too. It comes to the relationship between position of defect mode in photonic band gap and light group velocity, and it is proved theoretically using the principle of plane wave expand method.

Analysis of photonic crystal defect modes by maximal symmetrization and reduction

We analyze in depth the eigenmodes symmetry of the vectorial electromagnetic wave equation with discrete symmetry, using a recently developed maximal symmetrization and reduction scheme leading to an automatic technique which decomposes every mode into its most fundamental internal geometrical components carrying independent symmetries, the ultimately reduced component functions (URCFs). Using URCFs, geometrical properties of photonic crystal defect modes can be analyzed in great details. In particular we analytically identify the kind of modes that display non-vanishing transverse electric or transverse magnetic amplitude at the cavity center in C2v, C3v, C4v, and C6v symmetries, and their degeneracies. We also build a postprocessing tool able to extract and identify URCFs out of the modes whether from experimental or numerical origin. In the latter case it is independent of the eigenmode computation method. In another variant the whole eigenmode computation can be systematically reduced to a minimal domain, without any need for applying specific non-trivial boundary conditions. The approach leads to strong analytical predictions which are illustrated for specific H1 and L3 cavities using the postprocessing tool on full three-dimensional computed modes. It not only constitutes an unprecedented check of the symmetry of the computational results, but it is shown to also deliver a deep geometrical and physical insight into the structure of the modes of photonic bandgap microcavities, which is of direct use for most modern applications in quantum photonics.

Photocurrent response from photonic crystal defect modes

The authors use a quantum well intersubband photodetector fabricated into a two dimensional photonic crystal to investigate the optical defect modes of a single missing hole defect. The modes appear as a local enhancement in spectral photocurrent due to an increased in-coupling of surface incident light when a defect mode is present. The frequencies of these localized modes are tracked as they are varied by the defect geometry and compared to simulations.

Impact of a stripe waveguide to coupled defect modes of photonic crystals

Coupled defect modes of photonic crystals can be characterized by the transmission spectrum shape that is closely linked to the stripe waveguide connecting the defects. Unlike the direct coupling cases where the phase shift of lightwave depends only on the defect mode frequency, we found that for the waveguide coupling cases the waveguide length and the dispersion relation must be also considered. By changing the waveguide length, the spectrum can exhibit periodically three-peak appearance, two-peak appearance, and flat top appearance. At frequencies close to the defect mode, the results of the coupled mode theory are in good agreement with the simulations using the finite-difference time-domain technique, verifying the validity of the theoretical model even in the complicated cases.

Enhanced Photoconductivity in Thin‐Film Semiconductors Optically Coupled to Photonic Crystals

Photonic crystals (PCs) are a remarkable class of materials wherein the periodicity of the index of refraction can be engineered to obtain unprecedented optical properties that have no parallels in other materials. Some interesting optical phenomena inherent to PCs include second harmonic generation, the superprism effect, photonic bandgaps (PBGs), and “slow photons”. It is also possible to achieve light localization within PCs by introducing defects by design that disrupt the periodicity of the index of refraction, allowing the creation of localized photon modes having frequencies that lie within the PBG of the PC. The ability of defect modes in PCs to confine photons is expected to provide the infrastructure for optical circuits. Moreover, lossless light propagation along PBG waveguides with coupling to quantum dots or optical cavities could provide new avenues for quantum information processing. Considering that an ideal crystal is a periodic structure extending to infinity in all directions, the planar surface of a PC can actually be regarded as a 2D crystal defect. Accordingly, it is interesting to note that as in the case of defects introduced into the bulk of a PC, light can also be localized at the PC surface. For instance, it has been known for quite some time that light can propagate in localized modes along the surface of a periodically layered medium, which effectively acts a 1D PC. Recently, Miguez and co-workers have investigated photon surface resonant modes in thin films coupled to PCs. One structure studied in this work has been fabricated by depositing a homogeneous silica layer on top of a silica inverse colloidal crystal. The results of the study indicate that upon illumination of this layer of silica with normally incident light at certain frequencies within the bandgap of the PC, the electromagnetic field near the PC/film interface is amplified with respect to the electromagnetic fields in the surrounding regions. This phenomenon arises from partial light localization at the modified PC surface, which behaves as an optical dopant or defect. Structures similar to those studied by Miguez and co-workers have been used to enhance the efficiency of Gratzel cells comprising dye-sensitized titania electrodes shaped as PCs. The observed improvements were initially attributed to slow photons propagating through the PC structure; however, it has subsequently been pointed out that this hypothesis does not account for all of the observed results and that the improvements arise primarily from light localization at the surface of the structure. The objective of the research reported herein is two-fold. The first objective is to demonstrate that the photoconductivity of a semiconductor film can be amplified by optically coupling the film to a PC surface. Indeed, in this construct, the film does not itself need to be periodically structured. The second objective is to show that the photoconductivity enhancement attainable from surface resonant modes in thin films coupled to PC surfaces is greater than the enhancement that can be achieved by depositing a perfect mirror (PM) onto the backside of this film. To address the first objective, we have compared the measured quantum efficiencies (QEs) of a thin hydrogenated amorphous silicon (a-Si:H) film deposited on a glass substrate for two different structures. One structure is the film–PC construct shown in Figure 1a, wherein an opaline PC is deposited onto the backside of a thin a-Si:H film, whereas the secC O M M U N IC A IO N

Properties of omnidirectional gap and defect mode of one-dimensional photonic crystal containing indefinite metamaterials with a hyperbolic dispersion

The structure of one-dimensional photonic crystal (1DPC) containing indefinite metamaterials with a hyperbolic dispersion relation is proposed to realize the omnidirectional gap for the design of omnidirectional reflectors and filters. It is demonstrated that this 1DPC can result in a similar zero average index (zero-n¯) gap usually appearing in the 1DPC containing isotropic left-handed materials. The properties of zero-n¯ gap and defect modes of this photonic crystal are studied in detail. The edge of this zero-n¯ gap is insensitive to incident angle and polarization of light in contrast to the Bragg gap. When a defect layer is introduced into the 1DPC, a defect mode appears inside the omnidirectional gap. The spectral position of defect mode is found to be weakly dependent on the incident angle of light and nearly invariant to the scale length of photonic crystal.

Numerical simulation of photonic crystal defect modes using unstructured grids and Wannier functions

We compute the electromagnetic modes of a photonic crystal point defect by expansion in localized basis functions. The defect modes are expanded using Wannier functions formed from the eigenmodes of the surrounding photonic crystal. The underlying solution to the perfect crystal is based on a real-space solution to Maxwell's equations using the finite element method. The resulting method combines the efficiency and flexibility of using an unstructured grid to discretize the unit cell with the efficiency of the Wannier method, which provides a significant reduction in the number of unknowns (small bases), such as applied to the defect problems with strongly localized modes. We present numerical results for an example defect structure present in a crystal structure that offers convenient validation and comparison to other methods.