Photonic Quantum-well Structures Research Articles

Analysis of defect states in optical microcavities based on the photonic quantum well structure

The defect states in optical microcavities are demonstrated to be related to the different confinement states by analyzing the photonic band structure of the equivalent photonic quantumwell structure consisted of a photonic well confined by photonic barriers. Our results indicate that the defect states in optical microcavities could be divided namely into the localized, pseudo-localized, and non-localized modes, and explain the relationship between the localized states in optical microcavities and confinement effects of the electric field in the defect layers.

General way to obtain multiple defect modes in multiple photonic quantum-well structures.

We introduce a method to obtain and describe the multiple defect modes in the multiple photonic quantum-well structure [(AB)mC]n(AB)m. It is found that the relationship between structural parameters and defect modes can be obtained by analytically solving the dispersion relationship for the photonic crystal with its periodic unit [(AB)mC], and a laconic and unifying expression can be used to describe the energy levels of both the interface modes and defect modes. The internal mechanism to determine the related parameters is revealed. We believe that these findings can be used to provide direct guidance for practical application.

Double-negative multilayer containing an extrinsic random layer thickness magnetized cold plasma photonic quantum-well defect

Theoretically, the transmission properties of a symmetric double-negative metamaterial one-dimensional photonic crystal containing an extrinsic random layer thickness magnetized cold plasma photonic quantum-well defect structure have been investigated. From the numerical results performed by characteristics matrix method, it is found that, such type of structure possesses a transmission peak within the zero-n¯ gap. To design a tunable microwave filter, the effects of many parameters such as randomness of layer thickness of the multilayer defect in terms of standard deviation (σ), strength of external magnetic field (B) and electron density of magnetized cold plasma (ne) on transmission peak is discussed. Our findings show that the histogram for the central frequency of the transmission peaks becomes wider with respect to smaller values of σ. In addition, in the case of B, our investigations also reveal that the histogram shifts to the higher frequency range and vice versa while considering the case of ne. These findings help to design a tunable filter for different microwave applications.

CONTROLLING TUNNELING MODES BY A PHOTONIC QUANTUM WELL STRUCTURE BASED ON ZERO EFFECTIVE PHASE GAP

Light propagation through one-dimensional photonic quantum well (PQW) structures consisting of single-negative (SNG) materials is investigated theoretically. It is found that, based on the zero-effective-phase gap mechanism, the resonant tunneling modes can be manipulated to realized multiple channeled filters which are not only weakly dependent on the incident angle and polarization, but also insensitive to the deviation of the photonic barrier thickness. These properties are advanced to conventional PQW structures and the physical reason for the remarkable features of the proposed PQW structure is analyzed.

ANALYSIS OF TRANSMISSION PROPERTIES IN A PHOTONIC QUANTUM WELL CONTAINING SUPERCONDUCTING MATERIALS

Properties of wave transmission in a photonic quantum well (PQW) structure containing superconducting materials are theoretically investigated. We consider two possible PQW structures, (AB) P (CD) Q (AB) P -asymmetric and (AB) P (CD) Q (BA) P -symmetric, where the host photonic crystal (PC) (AB) P is made of dielectrics, A = SrTiO3, B = Al2O3, and the PQW (CD) Q contains C = A and superconducting layer D = YBa2Cu3O7ix, a typical high-temperature superconducting thin fllm. Multiple transmission peaks can be seen within the photonic band gap (PBG) of (AB) P and the number of peaks is directly determined by the stack number of PQW, i.e., it equals Q-1. Additionally, the results show that symmetric PQW structure is preferable to the design of a multichannel transmission fllter. The efiect of stack number of photonic barrier is also illustrated. Such a fllter operating at terahertz with feature of multiple channels is of technical use in superconducting optoelectronic applications.

Temperature-Dependent Tunable Photonic Channel Filter

In the present communication, we studied the 1-D photonic quantum-well (PQW) structure for the photonic channel filter. The PQW structure consists of a defect layer in Si/air multilayered regular 1-D photonic crystal. The extension of the work shows the temperature-dependent tuning in the channel filter.

Omnidirectional and tunable symmetrical confined states in photonic quantum-well structures with single-negative materials

The symmetrical confined states are found in photonic quantum-well structures with single-negative materials, in which the photonic barrier is based on the zero-effective-phase gap. The number and frequencies of the symmetrical confined states can be tuned by varying the period number and thicknesses of the well photonic crystal, respectively. Furthermore, the symmetrical confined states of the structures are less sensitive to the incident angle and polarization, compared with previous confined states of photonic quantum-well structures based on the Bragg or zero-average-index gap. The structures open a promising way to fabricate symmetrically tunable and omnidirectional multichannel filters for future dense wavelength division multiplexing applications.

High transmittance of connected resonant modes

We investigate the propagation of electromagnetic wave through photonic quantum-well structures constructed by one-dimensional photonic crystals with defect layers. It is shown that non-destroyed high transmittance of each separated resonant mode can be found if photonic quantum-well structures are properly connected. Experimental fabrication of combined photonic quantum-well structures is carried out, and the results agree with the numerical calculations very well.

含复介电常量一维光子晶体量子阱结构研究

The transfer matrix method is used to research the transmission spectra for one-dimensional photonic crystal of the solid dielectric constant and when containing the complex dielectric constant.The results show that the photonic quantum-well structure can be made up in both circumstances,and the position and struct of the transmission band spectra of the photonic quantum-well structure are the same.But the resonance transmission peak arises strong gain phenomenon in the circumstance that contains the negative imaginary part of the complex dielectric constant,and evident attenuating phenomenon in the circumstance that contains the positive imaginary part of the complex dielectric constant.

OMNIDIRECTIONAL FILTERING BASED ON ZERO-AVERAGED REFRACTIVE INDEX GAP IN PHOTONIC QUANTUM WELL STRUCTURES

A photonic quantum well (PQW) structure based on the zero-averaged refractive index gap is constructed and the transmission properties are investigated. Quantized confined photonic states resulting from the photonic confinement effect are observed. We find that the resonant transmissions are not only weakly dependent on the incident angle but also insensitive to polarization of light. More importantly, the number of the confined photonic states can be controlled by simply adjusting the cell number of the well photonic crystal. It is shown that strong field localization is found when the well photonic crystal consists of positive-index material or single negative material. Particularly for the PQW structure containing single negative material, the field in the well region can be highly enhanced by modulating the size of the well photonic crystal. These peculiar features make this PQW structure superior to the conventional PQW structure in potential applications such as omnidirectional filtering and optical bistable switching.

The design of a photonic crystal filter in the terahertz range

One-dimensional photonic crystal structures for multiple channeled filtering and polarization selective filtering in the terahertz (THz) range are studied theoretically. The design of aperiodic photonic quantum-well (APQW) structures for multiple channeled filtering and different polarization filtering at arbitrary preassigned frequencies are achieved by using the simulated annealing algorithm with a special merit function. The parameters of these filters can be expediently controlled and the transmission characters are polarization dependent. Numerical simulations show that the designed APQWs can meet the desired specification well.

Controlling thermal radiation by photonic quantum well structure with zero-averaged-refractive-index gap

Based on Kirchoff's second law, we investigate the spectral-directional thermal emissivity of a photonic quantum well (PQW) structure with a zero-averaged-refractive-index (zero-n¯) gap coating on an absorbing substrate. It is shown that the thermal emission through tunneling modes having frequencies in the zero-n¯ gap is not only weakly dependent on the emission angle and polarization state but also insensitive to the unit-cell size scaling of the barrier photonic crystal. More importantly, the PQW structure promises the frequency-selective thermal emission for both TE and TM polarization states along a well-defined direction. This may result in designing thermal antennas.

Influence of two-dimensional magnetic photonic quantum wells on resonant tunneling spectral character

The non-magnetic material closed photonic quantum well (PQW) and magnetic material PQW structures based on the non-magnetic material open PQW are proposed. The transmission spectra and the field distributions of these three PQW structures are calculated by finite-difference time-domain method, the quantized energy states are researched, and the feasibility of enhancing spectral intensity significantly by self-structure is disclosed. It is found that the optical transmittance of the magnetic PQW is close to 1, and the energy loss is less compared to non-magnetic PQW. Compared with the closed PQW structures, the device’s volume can be reduced, the degree of free regulation of the energy band project can be increased, and more photon bound states can be obtained. The results show that the open PQW is the traveling wave well, and its capability of capturing photons is weak. However, the closed PQW and the magnetic PQW are standing wave wells. Their capabilities for capturing photons are strong, while the light field gradient of the material PQW is bigger.

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.

Photonic quantum-well structures containing negative-index materials

The properties of photonic quantum-well structures containing negative-index materials are studied theoretically, showing features remarkably better than conventional photonic quantum-well structures. Owning to the zero- n ¯ gap of one-dimensional photonic crystals containing negative-index materials, the photonic quantum-well structures can be proposed as a multiple channeled filter which is very weak dependent on incident angle and polarization, and insensitive to the thickness disorder of the barrier photonic crystals.

Analysis of Three Coupled Defects in One-Dimensional PhotonicBandgap Structure

The mutual interaction of three different defects in photonic crystalsis studied theoretically. A theoretical model based on the classicalwave analogue of the tight-binding (TB) picture is applied to thestructure. We obtain analytic expressions for the eigenfrequencies andeigenmodes, from which the transmissions at resonance are derived.Based on this, a new type of the photonic quantum-well structure isinvestigated and its possible application is discussed. The TBpredictions are compared with the transfer matrix method simulationresults.

INVESTIGATION OF PROPERTIES OF THE CONFINED STATES IN PHOTONIC QUANTUM-WELL STRUCTURES

We present a detailed investigation of the properties of the confined states in the photonic quantum-well (PQW) structures with the use of the transfer-matrix method. The influences of various physical and geometrical parameters of the systems on the characteristics of the confined states are systematically explored. The results show that the features of the confined modes can be engineered by adjusting system parameters. It may provide a useful way to control the merits of the defect modes in order to match the requirements in photonic or microwave devices.

Resonant modes in quantum well structure of photonic crystals with different lattice constants

The resonant modes in a quantum well (QW) structure composed of three slabs of two dimensional (2D) photonic crystals with different lattice constants are analyzed with plane-wave-based transfer matrix method (TMM). It is found that the energy band of the well slab submerged into the band gap of barrier slab is discretized into quantized modes and the number of the resonant modes changes with the well slab thickness. A model structure of asymmetrical photonic QW consisting of two slabs of 2D photonic crystals with different lattice constants and one uniform dielectric slab in between is proposed and the resonant modes in it are investigated with the same method. A useful numerical simulation method for theoretical discussion as well as for practical application about photonic QW structure of photonic crystals with different lattice constants is proposed.

Properties of one-dimensional photonic crystals containing single-negative materials

The transmission properties of a one-dimensional photonic crystal containing two kinds of single-negative (permittivity- or permeability-negative) media are studied theoretically. We show that this structure can possess a type of photonic gap with zero effective phase (phi(eff) ). The zero-phi(eff) gap distinguishes itself from a Bragg gap in that it is invariant with a change of scale length and is insensitive to thickness fluctuation. In contrast to a photonic gap corresponding to zero averaged refractive index, the zero-phi(eff) gap can be made very wide by varying the ratio of the thicknesses of two media. An equivalent transmission-line model is utilized to explain the properties. A photonic quantum-well structure based on zero-phi(eff) gaps is proposed as a multiple channeled filter that is compact and robust against disorder.

Aperiodic photonic quantum-well structures for multiple channeled filtering at arbitrary preassigned frequencies

Designs of aperiodic photonic quantum-well (APQW) structures to achieve multiple channeled filtering at arbitrary preassigned frequencies are done by using the simulated annealing algorithm with a special merit function. The APQW structure consists of aperiodically stacked dielectric-layers sandwiched by two finite-length prototype photonic crystals (PCs). The insert of the APQWs can generate the specified defect states with predetermined frequencies. Numerical simulations show that the designed APQWs can achieve the desired specification.