One-dimensional Photonic Crystal Structure Research Articles

An ultracompact optical polarizer based on the one-dimensional photonic crystals containing anisotropic layers

The linear birefringence effect of the uniaxial anisotropic materials is utilized to design an optical polarizer in this paper. We propose a one-dimensional photonic crystal structure with an anisotropic defect layer to break the degeneracy of the TE and TM mode resonances. The band structures of the TE and TM mode polarizations are calculated using the plane wave expansion method, which has been generalized for the structures containing anisotropic materials. By increasing the refractive index contrast ratio of the HL pair layers of the crystal, we present an ultracompact structure with significant performance of a very high polarization extinction ratio (PER) and a very low insertion loss (IL). The presented polarizer, which operates at the near-infrared region centered at the wavelength of 1550 nm, is 2.67 μm long. It is obvious that the structure is considerably compact for the long wavelength of the third communication window. The polarizer can be designed in such a way that only the fields with a specific polarization direction (TM, TE, or any other direction) are transmitted.

Mechanical investigations of free-standing SiN membranes patterned with one-dimensional photonic crystal structures

A detailed investigation of the structural and vibrational properties of various prestressed silicon nitride membranes patterned with one-dimensional photonic crystal structures is presented. The tensile stress related deformation of the structure in the vicinity of the patterned area is determined by atomic force microscopy scans, while the resonance frequencies and quality factors of the out-of-plane membrane vibrations are measured using optical interferometry. We show that these noninvasive measurements, combined with the results of finite element simulations, provide accurate information on the tensile stress, the elasticity modulus, and the density of these nanostructured thin films. The obtained results are interesting in two ways: first, they show that such highly reflective thin membranes already exploited in various photonics applications possess high-mechanical quality, which also makes them attractive for optomechanics and sensing applications. Second, they represent a nondestructive method to determine key material parameters, which can be applicable to a broad range of fragile nanostructured thin films.

Thermal Stability Analysis of Surface Wave Assisted Bio-Photonic Sensor

In this paper, the thermal stability of a Bloch Surface Wave (BSW) assisted bio-photonic sensor is investigated. The structural analysis is carried out using the transfer matrix method (TMM). The design comprises a truncated one-dimensional photonic crystal (1D-PhC) structure along with a defective top layer. The structural parameters are optimized to excite a BSW at the top interface for an operating wavelength of 632.8 nm. The mode confinement is confirmed by using wavelength interrogation, angular interrogation and surface electric field profile. Further, the effect of thermal variation on BSW excitation angle and sensitivity is carried out. The analysis shows the average variations in excitation angle and sensitivity of about −0.00096 degree/°C and 0.01046 (degree/RIU)/°C, respectively. Additionally, the analysis is also extended towards different lower wavelengths of 400 nm and 550 nm, which provides average variations in the excitation angles of about −0.0027 degree/°C, and 0.0016 degree/°C. This shows that the structural sensitivity response is more thermally stable at the lower wavelength range. Thus, showing its potential applications in designing thermally stable bio-photonic sensors.

High anti-interference dual-parameter sensor using an EIT-like effect photonic crystal cavity coupled system.

We propose a sensor with high anti-interference ability using a photonic crystal cavity coupled system for simultaneous sensing of the refractive index (RI) and temperature (T) based on an electromagnetically induced transparency-like effect. A transparent window is achieved in the transmission spectrum through destructive interference between the air mode resonance and dielectric mode resonance in two one-dimensional photonic crystal structures. The T-sensitive material (SU-8) is used in the coupled system, promoting sensitivity and anti-interference ability. The capability of the system to simultaneously detect a small range of RI and T is demonstrated using three-dimensional finite-difference time-domain simulations and the fitting process. The RI sensitivities for the air and dielectric modes were 215 nm/refractive index unit (RIU) and 0 nm/RIU, respectively. The T sensitivities for the air and dielectric modes were 19 pm/K and -83pm/K, respectively. The sensor resists external interference, enabling it to resist the error caused by readings. The footprint of the sensor is 29×1.8µm2 (length×width), contributing to future optical on-chip integration sensor design.

Optical sensor for biomedical application based on photonic crystal with double defect

A symmetrical one-dimensional photonic crystal structure with double defects is investigated. The transfer matrix method is used to investigate the transmission characteristic of proposed design. Two distinct peaks are obtained in transmission spectra corresponding to double defect structure. The position of transmission peak and height shows dependence on the refractive indices of defect layer and separation between defect layers. The defect modes show blue shift along with lowering in transmission peak as refractive index of one defect layer decreases. The proposed structure can be used for comparative study of two kinds of materials having close refractive index values as an optical sensor application.

Simulation Study of In-Phase and Out-Phase Enhanced Absorption of Graphene Based on Parity–Time Symmetry One-Dimensional Photonic Crystal Structure

In the field of modern optical communication systems and photoelectric detection, new components with complex functions and excellent performance are urgently needed. In this paper, a graphene-based parity–time (PT) symmetry structure is proposed, which is achieved by preparing the graphene layer on the top of a PT-symmetry photonic crystal. The transfer matrix method was used to calculate the absorptance of graphene, and a unique amplified absorption effect was found. Meanwhile, the peak value and wavelength position of the absorption can be modulated via the applied electric field. The results show that by adjusting the negative square-wave electric field from −3.5 × 10−5 to −13.5 × 10−5 V/nm (or the positive square-wave electric field from 2 × 10−5 to 11 × 10−5 V/nm), the proposed structure can achieve in-phase (or out-phase) enhanced absorption for the communication wavelength 1550 nm, with the absorption of graphene from 17 to 28 dB (or 30 to 15 dB) corresponding to the square-wave modulation electric field change. The modulable absorption properties of graphene in the structure have potential in optoelectronic devices and optical communication systems.

(INVITED) Tungsten oxide films by radio-frequency magnetron sputtering for near-infrared photonics

Tungsten oxide WO3-x is a transition metal oxide and a wide bandgap semiconductor, with a wide range of possible optical and photonic applications. In dependence on the fabrication techniques different stoichiometric ratios (x) and crystalline phases are obtained, which end up with an overall polymorph and extremely versatile material, characterized by tailorable dielectric properties. In particular, WO3-x thin film deposition by Radio-Frequency (RF) sputtering techniques provides a precise control of thickness, composition and nanostructure. In this work we introduce and discuss a specific process of deposition, that is magnetron RF-sputtering as a suitable way to grow WO3-x thin films with selected properties. Possibility of integrating WO3-x thin film on to one-dimensional (1D) photonic crystal structures is also explored. Films are transparent in the near and short-wavelength infrared optical spectral range. Their quality is assessed by morphological, structural and compositional characterizations. Dielectric properties are characterized by optical spectroscopy and ellipsometry, the latter also evaluates the degree of optical anisotropy of thin films in their crystalline phase. An 1D photonics bandgap structure is designed, formed by a SiO2–TiO2 multilayer and capped with a 450 nm-thick transparent WO3-x film, so that surface confinement and local enhancement of the optical field at 1416 nm in the topmost WO3-x layer is obtained.

Characterization of spectral features of cavity modes in one-dimensional graphene-based photonic crystal structures

Characterization of spectral features of cavity modes in one-dimensional graphene-based photonic crystal structures

The transmissivity of one-dimensional photonic crystals comprising three phases nanocomposite layer for optical switching purposes

In the present work, we have demonstrated the optical properties of a one-dimensional photonic crystal structure in which silicon (Si) and a nanocomposite material represent the constituent layers. The nanocomposite (NC) layer is designed from nanoparticles (NPs) of silver (Ag) and Indium Tin Oxide (ITO) in a host medium of air. The optical properties of the proposed design have been theoretically investigated using the well-known transfer matrix method (TMM), Maxwell-Garnett model and generalized Rayleigh mixing formula as well. The numerical results deduce that the effective permittivity of the nanocomposite material is strongly affected by the type and filling fraction of the NPs. Moreover, the effect of other related parameters such as the thickness of NC layer, filling fractions of NPs, permittivity of the background dielectric medium, the radius of Ag NPs and carrier density of ITO NPs on the optical characteristics of our design is also considered. We believe that the proposed structure may be useful as optical filters, reflectors, and optical switches.

Design Method of Notch Filter Based on One-dimensional Photonic Crystal Band Structure

Design Method of Notch Filter Based on One-dimensional Photonic Crystal Band Structure

Tunable narrowband terahertz multichannel filter based on one-dimensional graphene-dielectric photonic crystal

In this work, low terahertz (THz) spectroscopic properties of defective one-dimensional graphene-dielectric photonic crystal (1D-GPC) structure are theoretically investigated and analyzed in detail. The 1D-GPC is composed of a periodic stack of graphene nanolayers separated by isotropic dielectric slabs (SiO2), including an air defect as a central layer. The study is carried out using the well known transfer matrix method. Our numerical simulations showed that the suggested structure exhibits comb-like resonant peaks in the first transmission band of the 1D-GPC. These peaks are narrow, fully separated from each other and their number density increases by increasing the number of periods of the structure. Tunability of the optical characteristics of the device is also explored, taking into account the dependencies to the incidence angle, width, thickness, and refractive index of the dielectric layers, and the chemical potential of graphene sheets. Our calculations reveal that these transmission channels exhibit tunable behaviors against the parameters mentioned above. The observed spectroscopic features of the proposed structure make it an ideal candidate to realize tunable narrowband multichannel filters.

Photonic crystal-based optical sensor for two-phase liquid compounds

In this paper, an ultra-compact sensor based on a one-dimensional (1D) photonic crystal (PC) structure with alternative layers of TiO2 and MgF2 consisting a defect layer in the middle is investigated. Two-phase liquid compounds including heavy oil with various contents of water, ethanol with different contents of water, and sea water with different contents of salt are infiltrated into the defect layer and the reflection spectra are simulated. Simulation results based on the transfer matrix method (TMM) show that the defect mode appearing in the photonic band gap (PBG) of the PC shifts to longer wavelengths by increasing the refractive index of the defect layer. Using the Lichtennecher method, the best average sensitivities of S=0.0188 nm-1, S=0.2911 nm-1, and S=0.0426 nm-1 are obtained respectively for the heavy oil, ethanol, and seawater through which the sample content in each compound can be calculated.

Performance analysis of Bloch surface wave-based sensor using transition metal dichalcogenides

In this manuscript, a highly sensitive Bloch surface wave (BSW)-based sensor is proposed for refractive index sensing analysis. The structure is designed using an one-dimensional photonic crystal (1D-PhC) structure. A top defective layer of transition metal dichalcogenides (TMDC) material with atomic layer thickness is introduced to confine a Bloch mode analogues to surface plasmon-like mode at the top interface. The detailed analysis is carried out to investigate the impact of number of TMDC monolayers on sensing performance. The wavelength (angular) interrogation provides the significant higher sensitivity of around 9650 nm/RIU (or 231°/RIU). Besides the sensitivity, the rigorous analysis of full-width-half-maximum (FWHM) and figure-of-merit (FOM) is also carried out and a FOM of around 48,250/RIU (38,500/RIU) has been reported. The proposed design possesses the advantage in terms of easy fabrication and integration capability to develop handheld senor systems, especially for biological and chemical sensing.

Omnidirectional absorption properties of a terahertz one-dimensional ternary magnetized plasma photonic crystal based on a tunable structure

In this paper, by using the transfer matrix method and introducing the plasma as the dispersion medium, we propose the tunable one-dimensional magnetized ternary plasma photonic crystal structure (APB)N, and study its omnidirectional absorption properties of TM wave in terahertz band, where A and B are two different dielectric layers, P is plasma layer, and studied the regulation of the frequency and peak of the absorption channel by the number of periods, the relative refractive index of the dielectric layer, length, density, collision frequency and magnetic field intensity of the plasma layer to the absorption channel frequency and peak value. Therefore, this paper provides an idea for the design of terahertz absorbers for omnidirectional plasma photonic crystals.

Resonant and non-resonant coupling of one-dimensional microcavity mode and optical Tamm state

Coupling between the optical Tamm states (OTS) and microcavity mode in one-dimensional photonic crystal (1DPhC) structures is investigated experimentally and numerically with the help of transfer matrix method in resonant and non-resonant conditions, as a function of the distance between the 1DPhC-metal interface and the cavity layer (in terms of number of bilayers, Ntop, between the Tamm cavity and the microcavity). The system under study comprised of twelve bi-layers of alternating SiO2/TiO2 thin films, a half-wave thick TiO2 microcavity region and a layer of silver metal on top of the structure. It is observed that the microcavity mode and the OTS repel each other when Ntop is reduced indicating strong coupling between the two modes. In the resonant condition, wherein the individual structure consisting of either microcavity alone or Tamm cavity alone are tuned for the configuration Ntop = 2, the coupled modes in the hybrid structures are simultaneously localized at metal-1DPhC interface and at the microcavity. In the non-resonant condition when the microcavity mode and the OTS in the individual structure are not tuned, the coupling between the modes for the hybrid structure with Ntop = 2 leads to an enhanced electric field intensity of the microcavity mode compared to that from the uncoupled microcavity mode. Consequently, four different configurations corresponding to the non-resonant condition, having different Ntop are studied experimentally. The last four TiO2 layers and the microcavity layer of all the fabricated samples were incorporated with carbon quantum dots (CQDs). Comparison of photoluminescence enhancement as a function of Ntop in coupled and uncoupled conditions is discussed.

Engineered telecom emission and controlled positioning of Er3+ enabled by SiC nanophotonic structures

Abstract High-precision placement of rare-earth ions in scalable silicon-based nanostructured materials exhibiting high photoluminescence (PL) emission, photostable and polarized emission, and near-radiative-limited excited state lifetimes can serve as critical building blocks toward the practical implementation of devices in the emerging fields of nanophotonics and quantum photonics. Introduced herein are optical nanostructures composed of arrays of ultrathin silicon carbide (SiC) nanowires (NWs) that constitute scalable one-dimensional NW-based photonic crystal (NW-PC) structures. The latter are based on a novel, fab-friendly, nanofabrication process. The NW arrays are grown in a self-aligned manner through chemical vapor deposition. They exhibit a reduction in defect density as determined by low-temperature time-resolved PL measurements. Additionally, the NW-PC structures enable the positioning of erbium (Er3+) ions with an accuracy of 10 nm, an improvement on the current state-of-the-art ion implantation processes, and allow strong coupling of Er3+ ions in NW-PC. The NW-PC structure is pivotal in engineering the Er3+-induced 1540-nm emission, which is the telecommunication wavelength used in optical fibers. An approximately 60-fold increase in the room-temperature Er3+ PL emission is observed in NW-PC compared to its thin-film analog in the linear pumping regime. Furthermore, 22 times increase in the Er3+ PL intensity per number of exited Er ions in NW-PC was observed at saturation while using 20 times lower pumping power. The NW-PC structures demonstrate broadband and efficient excitation characteristics for Er3+, with an absorption cross-section (~2 × 10−18 cm2) two-order larger than typical benchmark values for direct absorption in rare-earth-doped quantum materials. Experimental and simulation results show that the Er3+ PL is photostable at high pumping power and polarized in NW-PC and is modulated with NW-PC lattice periodicity. The observed characteristics from these technologically friendly nanophotonic structures provide a promising route to the development of scalable nanophotonics and formation of single-photon emitters in the telecom optical wavelength band.

Designing tunable narrow band filters using a plasma photonic crystal structure with sinusoidal modulated plasma defect layer

In this work, we have designed tunable narrow band filters using symmetric and asymmetric one-dimensional plasma photonic crystal structures. Both proposed structures contain a plasma defect layer that its electron density and therefore the refractive index can be modulated sinusoidally by an external electric or acoustic fields. The transmittance spectrum is obtained by using the transfer matrix method. The results have shown that in symmetric and asymmetric structures, one and two very sharp localized defect mode appears in the photonic band gap, respectively. The frequency of the defect modes and their transmittance intensity are studied by changing the amplitude and frequency of the applied external field to the plasma defect layer. It is observed that by increasing the modulation frequency and its amplitude, the defect mode frequencies change and shift toward the lower frequencies that can be introduced as tunable narrow band filters.

Realization of white LED using plasmonic-based photonic structure through reflection, absorption and transmission analysis

A novel notion is proposed in the present research to generate white color LED using plasmonic-based one-dimensional photonic crystal structure. The entire work manipulates with three distinct colors of the red, blue and green light-emitting diode to realize the aforementioned application. The physics behind the research deals with the effective refractive indices of the proposed photonic crystal, pertaining to the red, blue and green where the mathematics of the same is integrated with Maxwell’s differential equation and subsequently throughthe Helmholtz second order differential equation. However, the principle of operation deals with the reflection, absorption and transmission characteristics. The reflection and transmission can be studied through-plane wave expansion method whereas absorption is discussed through numerical investigation. Further, the generation of three distinct signal and white signal can be made using different photonic structure. Moreover, the combination of said one-dimensional photonic structure generates a signal of 350 nm–530 nm wavelength, which is the signal of white LED. Finally it is inferred that the efficiency of the proposed structures is high as compared to both cold and warm LED.

Highly sensitive and tunable terahertz biosensor based on optical Tamm states in graphene-based Bragg reflector

A highly sensitive and tunable biosensor at terahertz (THz) frequencies is proposed by using a composite structure of graphene and one-dimensional photonic crystal. The theoretical analysis and simulation results show that the sensitivity and figure-of-merit of the biosensor can reach 517.9°/RIU and 222.9RIU- 1, respectively. The high sensitivity of the biosensor originates from the excitation of optical Tamm states caused by graphene-based distributed Bragg reflector. By varying the voltage on graphene, we can electrically control the sensitivity and figure-of-merit of the biosensor. Furthermore, we have shown that the biosensor has a wide range (1.40–1.70) for measuring the refractive index of the sensing medium. We believe the biosensor has a good application prospect in the field of biological detection.

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.