One-dimensional Photonic Crystal Structure Research Articles

Enhancement of efficiency of second-harmonic generation from MoS2 monolayers in 1D Fibonacci photonic crystals

In this article, the increase of the efficiency of second-harmonic generation (SHG) from MoS2 monolayers embedded in different one-dimensional Fibonacci photonic crystal structures is investigated. The systems contain ZnS, SiO2, and MoS2 layers with the same thickness of ZnS and SiO2 films, which are arranged on the basis of different Fibonacci sequences. The transfer matrix method is used to calculate the forward and backward SHG efficiencies in the undepleted pump approximation. The thicknesses of the ZnS and SiO2 films are changed to obtain the maximum frequency conversion in different structures. Tuning the thicknesses causes the second-harmonic waves generated in each MoS2 monolayer to interfere constructively. Also, the fundamental and second-harmonic wavelengths are both located at the photonic band gap edges, where the density of electromagnetic modes and the nonlinear interaction time are enhanced. Our results show that the SHG efficiencies were increased in quasiperiodic photonic crystals with respect to the periodic structure with the same number of MoS2 layers. In Fibonacci photonic crystal structures there are more geometrical parameters that can be tuned to obtain the highest efficiencies. Furthermore, we used a Bragg mirror at one side of each structure to control the propagation direction of the generated second-harmonic waves and to decrease the backward waves, which led to enhancement of the forward waves.

Study on simultaneous sensing of gas concentration and temperature in one-dimensional photonic crystal

Based on the mixed effects of the defect mode and interface state, a one-dimensional (1D) photonic crystal (PC) structure used for simultaneous gas concentration and temperature measurement is proposed. Using multiple physical field numerical module of the finite element method, the reflection spectrum with two relatively independent peaks is formed. And the wavelengths of the reflection peaks can be shifted when the concentration of the gas filled in the photonic crystal and environment temperature are changed. The defect layer thickness, metal layer thickness and period of photonic crystal are optimized. Taking the toluene as temperature-sensing medium, and the mixture of air and ethylene as gas-sensing medium, the relationships between the reflection peaks and related physical quantities are studied. Gas concentration and temperature can be measured by analyzing the relative shift of position of two reflection peaks in reflection spectrum. The results show that gas sensitivity is 500pm/1% ranging from 0% to 3% and its Q factor is 471.4. Temperature sensitivity is 88.7 pm/°C ranging from −20 °C to 70 °C and its Q factor is 415.7. The structure is simple, highly sensitive, and dual-parameter sensing. The study has reference value for simultaneously detecting harmful gas leakage and temperature in the polluted environment.

Transmission Spectra of a Symmetric Photonic Crystal Structure with a High-Permittivity Interstitial Layer

Transmission spectra are recorded for a one-dimensional photonic crystal structure with the permittivity of the interstitial (or cavity) layer exceeding the permittivity of layers in Bragg mirrors by many times. It is shown that the transmission can be suppressed almost completely both in the photonic band gap (except for a narrow defect-mode region) and beyond it. Specific features of the energy density distribution of the wave field over the structure are revealed.

Suppressing the negative effect of UV light on perovskite solar cells via photon management

In spite of the explosive enhancement to the device performance of the perovskite solar cells (PSCs) over the past decade, the intrinsic instability and performance degradation under ultraviolet (UV) illumination still impedes applications of such solar-electric conversion devices. Herein, we propose novel photon management structures (PMSs) including one-dimensional photonic crystal (1DPC) and self-cleaning biomimetic moth-eye structure (BMES) for simultaneously shielding the PSCs from the harmful UV irradiation and enhancing light harvesting for the useful visible-near infrared (Vis-NIR) irradiation. Optical and electrical simulation models, which are validated by the experimental results, are carried out to investigate how the PMSs with various structure parameters influence the optical and electrical properties of the PSCs. It is proved that with optimized PMSs, the PSCs would perform remarkable high reflection for UV band and low reflection for Vis-NIR band. This can perfectly suppress the negative effects of UV light on PSCs as well as further improve the power conversion efficiency (PCE) of the photovoltaic devices.

Influence of the polarization and optical axis on the transmission behavior in a one dimensional photonic crystal containing uniaxial metamaterial

In this letter, we introduce a one-dimensional photonic crystal (1DPC) structure with a uniaxial metamaterial defect layer. It is proposed to control the transmitted wave of the defect mode by adjusting the orientation of the optical axis and incidence angle for both polarization states. The 4 × 4 transfer matrix method was employed to calculate the transmittance spectrum of the proposed structure. It is shown that the photonic band gaps, the intensity and the peak wavelength of the defect mode depends on the polarization, the orientation of the optical axis and the incidence angle of the wave, due to the strong anisotropy of the metamaterial. The transmittance spectrum curves at different optical axes of the uniaxial metamaterial and the distinct incidence angles are illustrated graphically. It is shown that the defect mode appears as a peak in the transmission spectrum. Pronounced contrasts in the intensity, wavelength positions of the defect mode and photonic band gap were demonstrated depending on the incidence angle and the orientation of the optical axis of the uniaxial metamaterial defect layer for both polarizations. Our structure offers a great variety of possibilities for designing and controlling the transmitted intensity of the defect mode.

Giant enhancement of second harmonic generation efficiency from MoS2 mono layers embedded in 1D photonic crystals

In this paper an enhancement of second harmonic generation efficiency which radiated from MoS2 monolayers embedded in one-dimensional photonic crystal structures is studied. The system contains air, SiO2 and MoS2 layers in periodic manner with the same thickness of air and SiO2 layers. The transfer matrix method is used for calculating the forward and backward second harmonic generated wave efficiencies in undepleted pump approximation. Our results show the giant enhancement of second harmonic generation efficiencies up to seven orders of magnitude only with $N=40$ MoS2 monolayers in the system. The results are obtained by tunning the thickness of air and SiO2 layers at about 1284 nm for fundamental wave of $\lambda = 810$ nm wavelength. Choosing the above thickness causes the second harmonic waves, generated in each MoS2 monolayers, to interference constructively. Both of the fundamental and second harmonic wavelengths are located at the photonic band gap edges where the density of electromagnetic modes and the nonlinear interaction time are enhanced. These two mechanisms help us to improve the second harmonic generation efficiencies. Increasing the segments numbers enhanced the overall thickness of MoS2 nonlinear layers which affect the phase matching conditions and decreased the SH efficiencies.

Spectra from a Photonic Crystal Structure with a Metallic Nanoparticle Monolayer

We have used the transfer matrix (T-matrix) method to calculate the transmission and reflection spectra of a one-dimensional photonic crystal structure with a metallic nanoparticle monolayer insert. We have studied the influence of the monolayer parameters and position on the defect modes for the photonic structure.

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.

Use of uniaxial ferroelectric material as a tunable double-optical filter based on polarization converter and splitting in photonic crystal

We have investigated the tunability of splitting, intensity and polarization conversion of the double optical filter in a one-dimensional photonic crystal (1DPC) structure containing anisotropic ferroelectric material, based on the Pockels effect. A 4 × 4 transfer matrix method has been used to investigate the optical properties of the proposed structure at oblique incidence of light with S polarized wave. The influences of the external electric field, and incidence angle on the tunability of the transmission and polarization conversion of the optical filter, will be investigated. Numerical results exhibit that large splitting and blue shifting of the defect modes can be achieved in the presence of the external electric field and incidence angle, respectively. Also, the results reveal that by the application of an external electric field to the anisotropic layer, for an incident plane wave with (S)-polarization, two transmitted wave containing both P and (S)-polarized wave is created. Moreover, by increasing the external electric field and incidence angle, the edges and wide of photonic band for two transmission coefficient TSS and TSP can be modulated.

Band structure of one-dimensional photonic crystal with graphene layers using the Fresnel coefficients method

In this paper, we have calculated the band structure of an instance of one-dimensional photonic crystal (1DPC) composed of double-layered dielectrics via the Fresnel coefficients method. Then, we supposed the addition of a thin layer of graphene to each dielectric layer and the given photonic crystal (PC) composed of dielectric–graphene composites. The effects of graphene layers on the PC band structure were evaluated. We found out that according to the effective medium theory unlike the TE polarization, the electric permittivity of the dielectric layers changed at TM polarization. As such, the band structure of PC for TM polarization changed, too. Moreover, instead of bandgap related to “zero averaged refractive index” an approximately omnidirectional bandgap appeared and a related bandgap to “[Formula: see text] = 0” disappeared. In addition, a new angular gap branch appeared at a new frequency at TM polarization in which the width of gap increased as the angle increased.

High-sensitivity Goos-Hanchen shift sensing based on Bloch surface wave

A novel and simple sensing scheme based on the giant Goos-Hanchen shift enhanced by the excitation of the Bloch surface wave in a truncated one-dimensional photonic crystal structure is proposed and experimentally demonstrated. The significantly enhanced Goos-Hanchen shift is directly measured by a position sensitive detector and the following amplifier. The bulk refractive index sensitivity of the sensor is investigated by utilizing sodium chloride solutions and glycerol solutions with different concentrations as test samples. The results show that the Goos-Hanchen shift sensor has a superior sensitivity of 2.0*10−9 RIU/nm, which outperforms the SPR enhanced Goos-Hanchen shift sensors.

High power tapered lasers with optimized photonic crystal structure for low divergence and high efficiency

High power tapered lasers are designed and fabricated. A one-dimensional photonic crystal structure in the vertical direction is adopted to narrow the far field divergence. The thickness of the defect layer and the photonic crystal layers are optimized by analyzing the optical field theoretically. For tapered lasers, the continuous-wave power is 7.3 W and the pulsed power is 17 W. A maximum wall-plug efficiency of 46% under continuous-wave operation and 49.3% in pulsed mode are obtained. The beam divergences are around 11° and 6° for the vertical and lateral directions, respectively. High beam qualities are also obtained with a vertical M2 value of 1.78 and a lateral M2 value of 1.62. As the current increases, the lateral M2 value increases gradually while the vertical M2 value remains around 2.

Study on sensing property of one-dimensional ring mirror-defect photonic crystal

Based on the photon localization and the photonic bandgap characteristics of photonic crystals (PCs), one-dimensional (1D) ring mirror-defect photonic crystal structure is proposed. Due to the introduction of mirror structure, a defect cavity is formed in the center of the photonic crystal, and then the resonant transmission peak can be obtained in the bandgap of transmission spectrum. The transfer matrix method is used to establish the relationship model between the resonant transmission peak and the structure parameters of the photonic crystals. Using the rectangular air gate photonic crystal structure, the dynamic monitoring of the detected gas sample parameters can be achieved from the shift of the resonant transmission peak. The simulation results show that the Q-value can attain to 1739.48 and the sensitivity can attain to 1642 nm ⋅ RIU[Formula: see text], which demonstrates the effectiveness of the sensing structure. The structure can provide certain theoretical reference for air pollution monitoring and gas component analysis.

Single nanoparticle trapping based on on-chip nanoslotted nanobeam cavities

Optical trapping techniques are of great interest since they have the advantage of enabling the direct handling of nanoparticles. Among various optical trapping systems, photonic crystal nanobeam cavities have attracted great attention for integrated on-chip trapping and manipulation. However, optical trapping with high efficiency and low input power is still a big challenge in nanobeam cavities because most of the light energy is confined within the solid dielectric region. To this end, by incorporating a nanoslotted structure into an ultracompact one-dimensional photonic crystal nanobeam cavity structure, we design a promising on-chip device with ultralarge trapping potential depth to enhance the optical trapping characteristic of the cavity. In this work, we first provide a systematic analysis of the optical trapping force for an airborne polystyrene (PS) nanoparticle trapped in a cavity model. Then, to validate the theoretical analysis, the numerical simulation proof is demonstrated in detail by using the three-dimensional finite element method. For trapping a PS nanoparticle of 10 nm radius within the air-slot, a maximum trapping force as high as 8.28 nN/mW and a depth of trapping potential as large as 1.15×105 kBT mW−1 are obtained, where kB is the Boltzmann constant and T is the system temperature. We estimate a lateral trapping stiffness of 167.17 pN·nm−1· mW−1 for a 10 nm radius PS nanoparticle along the cavity x-axis, more than two orders of magnitude higher than previously demonstrated on-chip, near field traps. Moreover, the threshold power for stable trapping as low as 0.087 μW is achieved. In addition, trapping of a single 25 nm radius PS nanoparticle causes a 0.6 nm redshift in peak wavelength. Thus, the proposed cavity device can be used to detect single nanoparticle trapping by monitoring the resonant peak wavelength shift. We believe that the architecture with features of an ultracompact footprint, high integrability with optical waveguides/circuits, and efficient trapping demonstrated here will provide a promising candidate for developing a lab-on-a-chip device with versatile functionalities.

Band structure of one-dimensional doped photonic crystal with three level atoms using the Fresnel coefficients method

We consider a one-dimensional photonic crystal (1DPC) composed of double-layered dielectrics. Electric permittivity and magnetic permeability of this crystal depends on the incident electromagnetic wave frequency. We suppose that three level atoms have been added to the second layer of each dielectric and this photonic crystal (PC) has been doped. These atoms can be added to the layer with different rates. In this paper, we have calculated and compared the band structure of the mentioned PC considering the effect of added atoms to the second layer with different rates through the Fresnel coefficients method. We find out that according to the effective medium theory, the electric permittivity of the second layer changes. Also the band structure of PC for both TE and TM polarizations changes, too. The width of bandgaps related to “zero averaged refractive index” and “Bragg” increases. Moreover, new gap branches appear in new frequencies at both TE and TM polarizations. In specific state, two branches of “zero permittivity” gap appear in the PC band structure related to TM polarization. With increasing the amount of the filling rate of total volume with three level atoms, we observe a lot of changes in the PC band structure.

The effect of the hydrostatic pressure and temperature on the defect mode in the band structure of one-dimensional photonic crystal

In this work using the plane wave expansion method we study the effects of hydrostatic pressure and temperature on the defect mode in the band structure of a one-dimensional photonic crystal. This crystal made of alternating layers of GaAs and air, it is considered that the defect is GaAs with a dielectric constant as a function of pressure and temperature. It is found within the gap of forbidden frequencies the presence of a defect mode, which presents a shift to high frequencies as the pressure increases due to a decrease in the dielectric constant of GaAs. These results are in accordance with the electromagnetic variational theorem. Additionally, it is found that increasing the defect thickness increases the number of modes within the gap of prohibited frequencies.

Controlling Optical Absorption of Graphene in Near-infrared Region by Surface Plasmons

Nowadays, graphene has many applications in optical instruments, biosensors, gas sensors, photovoltaic cells, and so on. In this study, we aimed at investigating the optical properties of graphene under the influence of plasmons created in one-dimensional photonic crystal structure by making use of the absorption spectrum. We put the gold photonic crystal in adjacent to graphene and placed an antireflection layer on top of it. Then, we studied the behavior of graphene absorption peaks in a near-infrared region. By analyzing the graphene behavior in this region, we observed that graphene absorption was increased up to 40% and graphene absorption value in absorption peak, absorption peak wavelength, absorption spectra width, and also its absorption spectra in a wide wavelength range from 1000 to 2500 nm, could be controlled by making use of different factors such as the substance of antireflection layer and photonic crystal geometric dimensions. This structure can make many applications possible for graphene such as using it to build biosensors to identify uric acid and some of the lipids that have specific significances in detecting atherosclerotic lesions as well as diagnosing the states of disease.

Superconductor based ternary periodic multilayered structure as a single and multichanneled filter in the terahertz region.

A single as well as a multichanneled filter in the terahertz region has been proposed by designing a one-dimensional photonic crystal (PhC) structure using a high-temperature superconductor air-dielectric ternary periodic structure. The filter is designed without incorporating any defect, which has rarely been proposed in a ternary PhC structure. The theoretical study of transmittance was performed by applying the transfer matrix method. The transition from single channel to desired multichannel is achieved by adjusting the number of periods. Furthermore, the impact of the thicknesses and dielectric constants of the constituting layers was investigated. In addition to this, the tunability is achieved by the influence of temperature-dependent dielectric constant of the superconductor.

High-temperature degradation of one-dimensional metallodielectric (W/SiO2) photonic crystal as selective thermal emitter for thermophotovoltaic system

In this paper, thermal stability of a one-dimensional metallodielectric photonic crystal (1D MDPhC) structure based on W and SiO2 for thermophotovoltaic systems is reported. The thermal degradation mechanism of the structure, in its operating temperature range, is thoroughly investigated by using energy dispersive spectroscopy (EDS) with transmission electron microscope (TEM) and depth-profiling X-ray photoelectron spectroscopy (XPS). It is found that the structure is entirely destroyed under 1400 K by an inter-diffusion process forming a mixture of W and SiO2 without measurable oxidization of W. But, long-term annealing results in oxidization of W layer even at a lower temperature of 1300 K. During the long-term annealing, oxygen atoms in outside atmosphere are believed to cause oxidation of the upper W layer below the top SiO2 layer. Additionally, delaminated spots are observed over the surface. These thermal behaviors are potential clues to prevent or minimize thermal degradation of the multilayer structure under high temperature operation.

Electrically tunable all-optical diode in a one-dimensional photonic crystal structure.

All-optical-diode tunability with externally applied voltage in a one-dimensional photonic crystal structure of arrangement (BA)5/AgLiNbO3Ag/(AB)5(AABB)5 was investigated. It is an asymmetric hybrid Fabry-Perot resonator which is composed of distributed Bragg reflector segments (AB5) containing the linear (B layers) and nonlinear (A layers) optical materials. The LiNbO3, (LNO) sandwiched with two pairs Ag layers, is employed as a defect. The electro-optical (EO) effect and optical nonlinear response (Kerr effect) of LNO is considered. The linear transmittance (LT) spectrum, nonlinear transmission (NT) curves and field distribution, for left to right (L-R) and right to left (R-L) incidents at different applied voltages are graphically illustrated. Results show that with an increase in the applied voltage, L-R and R-L NT curves deflect, amplify, and compress in comparison to zero applied voltage. At negative voltages, due to accumulation of the EO and Kerr effects, variations are more sensitive. The EO effect in LNO causes tunability of the LT spectrum, and the Kerr effect in nonlinear layers dynamically tunes the optical bistability threshold. The results of this study can be useful in designing externally tunable basic elements for optoelectronic devices.