One-dimensional Photonic Crystal Heterostructure Research Articles

Angle-insensitive transmission and absorption with a PT phase transition via coupled interface states in hybrid one-dimensional photonic crystal heterostructures

Angle-insensitive transmission and absorption with a PT phase transition via coupled interface states in hybrid one-dimensional photonic crystal heterostructures

Multi-band tunable strongly nonreciprocal thermal radiation in topological edge state coupled mode

Violating Kirchhoff's law of thermal radiation can break the reciprocity constraints on spectral emissivity and absorptivity, which provides new capabilities for managing photonic heat flow and fundamentally improves energy harvesting systems' efficiency. Currently, most micro-nano structures that violate Kirchhoff's law are mainly confined to single- or dual-band models, significantly limiting applications such as photonic energy conversion and thermal management. Here, a scheme is proposed for a topological one-dimensional photonic crystal heterostructure consisting of multiple photonic crystals and Weyl semimetals, and its absorptivity and emissivity are theoretically calculated by the transfer matrix method. The results show that the multi-band nonreciprocity that completely violates Kirchhoff's law can persist over broad angular and frequency ranges without requiring any external magnetic field via tuning the relevant parameters. Furthermore, the electric field distribution reveals that the formation of such multiple bands originates from the coupling between topological edge states, and the significant enhancement of the local field near the interface of the heterostructure provides favorable conditions for the realization of strong nonreciprocity. Our work may contribute to the design and development of multiband nonreciprocal devices for energy conversion and thermal management and may also provide design ideas for multiband reciprocal absorbers, filters, optical switching, etc.

Topologically protected multiple resonant modes in a one-dimensional photonic crystal heterostructure

This paper proposed and theoretically examined a double-interfaced one-dimensional photonic crystal heterostructure for strong localization of topologically protected resonant modes. It is challenging to achieve these modes for a range of wavelengths using a single photonic crystal. The design proposed in this study is a heterostructure of photonic crystals 1 (PC1) and 2 (PC2), and it provides distributed localized modes from the infrared to ultraviolet wavelength ranges. In addition, multiple resonant modes occur at certain photonic bandgaps due to the addition of the third photonic crystal (PC3), which is analytically modeled with the heterostructure of PC1 and PC2. The enhancement in the number of resonant modes depends on the PC2 number of unit-cells and the reflection phase of the proposed heterostructure. The reflection phase is abruptly changing from 0 to π for several wavelengths inside the bandgap. These resonance modes are also dependent on the topological behavior of each connected photonic crystal and are immune to small disorder and back-scattering within the crystal. The high-quality factor (Q-factor ∼107) shows strong light–matter interaction of these multiple resonant modes. The characterization was done in terms of the Zak phase, sign of the reflection phase, and bandgap overlapping. Consequently, this heterostructure may pave the way for new topological photonics and new applications in optoelectronics, frequency up-conversion, photonic devices, rainbow trapping, multiwavelength optical filters, and so on.

Perfect light absorber with a PT phase transition via coupled topological interface states

Recently, the concepts of parity–time (PT) symmetry and band topology have inspired many novel ideas for light manipulation in their respective directions. Here we propose and demonstrate a perfect light absorber with a PT phase transition via coupled topological interface states (TISs), which combines the two concepts in a one-dimensional photonic crystal heterostructure. By fine tuning the coupling between TISs, the PT phase transition is revealed by the evolution of absorption spectra in both ideal and non-ideal PT symmetry cases. Especially, in the ideal case, a perfect light absorber at an exceptional point with unidirectional invisibility is numerically obtained. In the non-ideal case, a perfect light absorber in a broken phase is experimentally realized, which verifies the possibility of tailoring non-Hermiticity by engineering the coupling. Our work paves the way for novel effects and functional devices from the exceptional point of coupled TISs, such as a unidirectional light absorber and exceptional-point sensor.

Tunable Fano resonance in coupled topological one-dimensional photonic crystal heterostructure and defective photonic crystal

In this paper, we theoretically investigate the transmission properties of a structure composed of a topological one-dimensional photonic crystal (1D PhC) heterostructure and a conventional 1D PhC containing indium-antimonide (InSb) as a defect layer using the transfer matrix method. The phenomenon of Fano resonance can be achieved by coupling the defect mode with the topological edge state mode, which is supported by the topological PhC. The numerical results show that a narrow Fano resonance is observed in the transmission spectrum of the structure in the presence of the external magnetic field applied to the InSb defect layer. The optical properties of the InSb defect layer, and, therefore, the Fano resonance, can be dynamically controlled by changing the applied external magnetic field. The results obtained with the proposed structure reveal that the magnetic field has the greatest influence on controlling the optical properties of the Fano resonance. These findings could be beneficial for optical devices such as optical filters, sensors, and optical switches.

Enhancement and manipulation of group delay based on topological edge state in one-dimensional photonic crystal with graphene.

In this paper, the reflected and transmitted group delay from a one-dimensional photonic crystal heterostructure with graphene at communication band are investigated theoretically. It is shown that the negative reflected group delay of the beam in this structure can be significantly enhanced and can be switched to positive. The large reflected group delay originates from the sharp phase change caused by the excitation of topological edge state at the interface between the two one-dimensional photonic crystals. Besides, the introduction of graphene provides an effective approach for the dynamic control of the group delay. It is clear that the positive and negative group delay can be actively manipulated through the Fermi energy and the relaxation time of the graphene. In addition, we also investigate the transmitted group delay of the structure, which is much less than the reflected one. The enhanced and tunable delay scheme is promising for fabricating optical delay devices like optical buffer, all-optical delays and other applications at optical communication band.

Angular-adjustable single-channel narrow-band filter based on one-dimensional photonic crystal heterostructure

In this work, we designed a narrow-band filter based on a one-dimensional photonic crystal heterostructure featuring an angle-adjustable single-channel. The design presented here is based on a quarter-wave reflector with a mirror defect layer in the middle of the structure. By combining two defective one-dimensional photonic crystals (PCs), we obtained a heterostructure in which the two sub-PCs had the wavelengths of their defect modes, that is, the same at one incident angle and different at all other incident angles. This structure possessed the single-channel resonant peak in the transmission spectrum under either a normal or an oblique incident angle, and the angle-adjustability was related to the two modifying parameters. The filter based on this heterostructure possessed not only a narrow passband but also a sharp angular pass breadth. These properties have potential applications in angular tunable, single-channel narrow-band filters.

Light localization in one-dimensional photonic crystal heterostructures

Effects of both metamaterial inclusion and lack of inversion symmetry on the localized modes in one-dimensional photonic heterostructures under normal incidence are investigated. Each structure consists of two semi-infinite photonic crystals separated by an interface or by several layers. A general condition for light localization between semi-infinite crystals is given by parallelism between two-dimensional vectors in the electromagnetic (H, E) space. The case of a defective photonic crystal is recovered by joining crystals having the same unit cell. The defect modes display leftward and rightward damped oscillations with the same ratio, even when the unit cell lacks inversion symmetry. Their frequencies are found in good agreement with peaks of the transmittance through truncated structures. In heterostructures including metamaterials, an anomalous exponential decay of the magnetic field is found near one edge of the zero-〈n〉 gap.

Research on acousto-optic switch based on optical tamm state

An acousto-optic switch scheme based on optical tamm state (OTS) is proposed. The acousto-optic switch’s structure is one-dimensional photonic crystal heterostructure, which is composed of three materials: silicon dioxide, gallium arsenide and tellurium dioxide. All three materials are acousto-optic materials, which can ensure the acousto-optic effect when the ultrasonic wave and the light wave are incident at the same time. Due to the acousto-optic effect, the refractive index and thickness of one-dimensional photonic crystal heterostructures are changed by ultrasonic. The acousto-optic switch changes the ultrasonic amplitude to shift the intrinsic wavelength of OTS to the shorter wave direction. With the increase of ultrasonic amplitude, the intrinsic wavelength of OTS hardly changes after the amplitude exceeds 0.4 nm. This means that the ultrasonic wave with an amplitude of 0.4 nm can shift the intrinsic wavelength to 1538 nm. The acousto-optic switch realizes the on-off function within the permitted range. In this paper, the theoretical model of the acousto-optic switch is established. The propagation of ultrasonic wave in one-dimensional photonic crystal heterostructure is analyzed by theoretical model. The propagation of light in the medium after acousto-optic effect is analyzed by transmission matrix method. The simulation is carried out through COMSOL Multiphysics software. The results show OTS exists and localization can be seen in the electric field diagram. The acousto-optic switch of 1548.8–1551.7 nm can be realized by applying certain amplitude of ultrasonic or not. In this wavelength range, the extinction ratio is not lower than 12 dB and the insertion loss is not higher than 0.97 dB. The maximum extinction ratio is 13.17 dB, and the minimum insertion loss is only 0.65 dB. The acousto-optic switch of 1536.6–1543.3 nm can be realized by applying ultrasonic wave with amplitude corresponding to the length of incident light. In this wavelength range, the extinction ratio is not lower than 12 dB, and the insertion loss is not higher than 0.99 dB. The maximum extinction ratio is 13.15 dB, and the minimum insertion loss is only 0.65 dB. The response time of the acousto-optic switch is less than 13 ns. The acousto-optic switch has the characteristics of high extinction ratio and low insertion loss. It has a good application prospect and can be effectively applied in future optical communication.

Low-Threshold and Tunable Optical Bistability Based on Topological Edge State in One-Dimensional Photonic Crystal Heterostructure With Graphene

In this article, we present a theoretical analysis of the optical bistability phenomenon of the transmitted light beam in a graphene-based one-dimensional photonic crystal heterostructure in terahertz frequency range. This low-threshold optical bistability originates from the enhancement of the local electric field owing to the excitation of topological edge state at the interface between the two proposed one-dimensional photonic crystals. The results of calculation and simulation show that the hysteretic behavior and the threshold of optical bistability can be adjusted continuously by changing the applied voltage of the graphene. Moreover, the optical bistability of this structure also can be modified by the angle of the incident light and the number of graphene layers. Our findings provide a new method for realizing low threshold and tunable optical bistability in terahertz range, indicating excellent application prospects in the field of all-optical switches and other optical bistable devices.

Queer behaviors of multiple interface states in nonlinear photonic crystal heterostructure

Multiple interface states can be generated in one-dimensional photonic crystal heterostructure containing nonlinear material assisted by the Dirac Point. We present the queer behaviors of the multiple interface modes and it is found that these interface modes can be well described by a simple function. By adjusting the temperature of the system, the corresponding interface modes can be adjusted, however, we found that the same function can also be used to describe the energy levels of the interface modes for different temperatures, and we further reveal the meaning of relevant parameters. As applications, we calculate the second harmonic generation (SHG) under this system and it is easy for this system to make both the fundamental wave and second-harmonic wave simultaneously as the interface modes which have a strong localized field distribution at the interfaces. It is found that the tunable multiple wavelength SHG conversion efficiencies are more than 10000 times higher than that of quasi-phase-matching optical superlattice. We believe that these findings can be used to provide direct guidance for practical application.

Ultra-narrow unidirectional transmission filter assisted by topological interface state in one-dimensional photonic crystal heterostructure

A novel optical device with dual functions of ultra-narrow wave filtering and unidirectional transmission is proposed based on a topological interface state in a one-dimensional (1D) photonic crystal (PC) heterostructure. The structure is a 1D PC heterostructure connected with a dielectric grating. When light waves are incident from the PC side, topological interface states can be excited at a very narrow wavelength span. Within this span, light can transmit through the PC heterostructure easily and then be diffracted to the other side of the grating. However, for the reversed incidence, light will hardly transmit through the structure because the excitation conditions of the topological interface states are affected by the diffraction of the grating. Theoretical calculations demonstrate that the transmission difference between opposing incidences can reach 90%. Meanwhile, the high quality factor of the topological interface state resonance enables the structure to be an excellent filter. For operating frequencies in the communication range, the bandwidth of the unidirectional transmission can be as narrow as 0.2 nm. This ultra-narrow unidirectional transmission resonant filter has great potential in future all-optical integrated circuits.

Comparative study of one-dimensional photonic crystal heterostructure doped with a high and low-transition temperature superconducting for a low-temperature sensor

In this work, we present a theoretical study dealing with the sensitivity to physical parameters such as defect nature and thickness, and temperature. Indeed, the sensitivity considerably enhanced via the use of one-dimensional photonic crystal heterostructure (1D-PCH) which is composed of a few layers of ordinary materials, and superconducting defects. The aim of this paper is to compare the sensitivity of two proposed models consisting of (a) 1D-PCH doped with a high-transition temperature superconductor (Yttrium barium copper oxide (YBCO)), and (b) 1D-PCH doped with a low-transition temperature superconductor (niobium nitrure (NbN)). By using the transfer-matrix method (TMM), it has been demonstrated that model (b) is very sensitive compared to model (a). Therefore, the superconducting defect nature on 1D-PCH, using a few layers can play a fundamental role in a very low-temperature sensor.

Facile way to obtain multiple interface modes in a photonic crystal heterostructure.

A very facile way to obtain multiple interface modes in a one-dimensional photonic crystal heterostructure is proposed in this Letter. We found that the interface modes can be generated by introducing the interfaces, and the number of interface modes equals the number of introduced interfaces. All these interface modes originating from a different geometric Zak phase can create two band branches governed by the two different interfaces. We further find that the two band branches can be renormalized into one band branch with discrete energy levels in the form of sinusoidal function. We believe that these findings can be used to provide direct guidance for practical application and can also make the estimation of practical samples more convenient.

Effect of dispersion on omnidirectional reflection band in zinc oxide-based one-dimensional photonic crystal heterostructures

We report a numerical study of the effect of material dispersion on the omnidirectional reflectors (ODR) properties in the case of one-dimensional photonic crystal structures consisting of alternate layers of zinc oxide as material of high refractive index and SiO2 as material of low refractive index. The interplay of dispersion and structural parameters on the ODR properties of the structure of interest has been analyzed. Taking into account the material dispersion properties, shift in the wavelength range for ODR from (1079 − 1158 nm) to (1133 − 1103 nm) is observed. This shows the narrowing of the bandwidth for ODR from 79 to 30 nm as a result of material dispersion. The wavelength range of interest is close to optical communication wavelengths and is useful in many optical device applications.

Extremely small wavevector regime in a one-dimensional photonic crystal heterostructure for angular transmission filtering.

One-dimensional photonic crystals (PCs), when operating near the band edge in the dispersion diagram, inherently possess nearly polarization-independent angular selectivity-an angular transmission window around the normal direction with reflection for other angles. However, the incident light is mostly reflected at the PC-air interface due to large impedance mismatch. We show that the reflection may be sufficiently suppressed by utilizing a specially designed antireflection structure consisting of a PC having a different pitch from that of the host PC. The underlying mechanism is that the interfaces of the antireflection PC with the host PC and the air structure are selected such that the transverse impedance has a real value, which is positioned at the center of the thickness of a material film. Moreover, our structure provides a high-throughput wide angular transmission window, including the normal direction in both s and p polarizations. We develop an analytical model that captures the angular selectivity observed in numerical results.

Photonic bandgap compensation and extension for hybrid quasiperiodic heterostructures

Based on the idea of multiple photonic bandgap (PBG) overlapping for a one-dimensional photonic crystal heterostructure, a novel hybrid quasiperiodic heterostructure is proposed to enlarge the omnidirectional photonic bandgap (OPBG). The heterostructure is formed by combining Fibonacci and Thue-Morse quasiperiodic structure. The results show that the OPBG of the heterostructure is enlarged obviously, which increases about three times compared with that of Fibonacci quasiperiodic structure, and twelve times compared with that of Thue-Morse quasiperiodic structure. The influences of structural parameters, such as period number and generation number, on PBGs of Fibonacci and Thue-Morse quasiperiodic structure are studied respectively. The results show that the parameters have little effects on PBG widths of the two quasiperiodic structures. The influences of the refractive indexes and thickness values of the high and low refractive index materials on OPBG of the heterostructure are also investigated. The results show that the OPBG of the heterostructure can be further broadened by increasing the refractive index ratios and thickness values of the high and low refractive index materials. The reason why the quasiperiodic structure can easily realize the multiple band gap overlapping is analyzed by comparing the bandgap properties of periodic structure. The number of PBGs of the quasiperiodic structure in the same wavelength range is more than that of the periodic structure. Moreover, with the increase of generation number of the quasiperiodic structure, due to the occurrence of PBG split, the number of PBGs increases obviously, and each PBG width is less than that of the periodic structure. Owing to this kind of PBG characteristic of the quasiperiodic structure, the heterostructure formed by cascading the two quasiperiodic structures is more prone to realizing the multiple PBG overlapping than other heterostructures, thus more easily achieving the expansion of OPBG. These results lay the design foundation for the compensation and broadening of the more complex bandgap structure.

Enlarged omnidirectional photonic band gap in heterostructure of plasma and dielectric photonic crystals

In this paper, we have shown theoretically that total omnidirectional photonic band gap (OBG) is enlarged considerably by using one-dimensional photonic crystal heterostructure composed of dielectric–dielectric and dielectric-plasma periodic structures. The OBG originates from a Bragg gap. The reflectance of considered structures are calculated by transfer matrix method (TMM). From the analysis it is found that the heterostructure of dielectric photonic crystals (DPCs) and plasma photonic crystals (PPCs) has very wide range of total OBG for both polarizations in comparison to the DPCs or PPCs, and the OBG can be notably enlarged by increasing the thickness and density of plasma layer.

Different kinds of band-pass filters based on one-dimensional photonic crystal heterostructures

Three kinds of band-pass filters (BPFs), termed a TE BPF, a TM BPF and a BPF at oblique incidence, are designed by crossing the band edges of two different one-dimensional (1D) photonic crystals (PCs). The TE BPF, fulfilling the function of high reflectivity for p-polarization and high transmittance in a narrow pass-band for s-polarization, is constructed by two subPCs, one of which is obtained by decreasing the lattice constant of the other one while the other parameters keep the same. The TM BPF also comprises two subPCs, but the materials of one subPC are quite different with those of the other one. Similarly, the BPF at oblique incidence, from which both polarization waves can transmit in a narrow pass-band at oblique incidence, is composed of two different subPCs. Note that, the distribution of the wave impedance of material in each BPF should be periodic to prevent unexpected defect modes. The new filters not only provide narrow pass-bands and wide non-transmission bands, but also have simple structures. This is a result of the fact that the wave impedance ratio between composites is enlarged by introducing magnetic materials. The new designs have potential applications in optical filters and optical integrated circuits.

A MID-INFRARED MULTICHANNELED FILTER IN A PHOTONIC CRYSTAL HETEROSTRUCTURE CONTAINING NEGATIVE-PERMITTIVITY MATERIALS

A design of mid-infrared frequency multichanneled transmission filter in a one-dimensional photonic crystal heterostructure containing negative-permittivity materials is proposed. It is found that the number of resonant peaks in transmittance is just related to the stack number. These peaks are located within the pass band of the ideal host photonic crystal, which is fundamentally different from that of using photonic quantum well structure. The peak positions can be tuned by varying the thicknesses of the two constituent layers. In addition, they are also shifted as a function of angle of incidence for both the transverse electric (TE) and the transverse magnetic (TM) waves.