Position Of Transmission Peak Research Articles

Narrowband Filters Designed from Hybrid One-Dimensional Periodic/Quasiperiodic Photonic Crystals with a Single Defect Layer

We report the transmission spectra and electric field amplitudes of electromagnetic modes propagating in hybrid periodic/quasiperiodic multilayer photonic structures in one dimension (1D). We consider the case of the combination of biperiodic Bragg mirror and triperiodic Bragg mirrors with quasiregular (FB, Fibonacci) layered components. The corresponding hybrid structure (HB) is formed by concatenating BM(N)-FB(M)-BM(N), where N (M) means the number of periods (sequence order) used for the Bragg mirrors (FB) structure. A single defect layer (D) is considered in the middle of two HBs (HB-D-HB). Optimizing the parameters (the order of sequence, number of Bragg mirror layers, thickness, and the refractive index of D) allows us to obtain narrowband filters. The manipulation of these parameters fixes the number of photonic band gaps as well as the position of transmission peaks. The existence of the selectively localized behavior of some optical modes in the structures is discussed.

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.

High Sensitivity Plasmonic Sensor Based on Metal–Insulator–Metal Waveguide Coupled with a Notched Hexagonal Ring Resonator and a Stub

In this paper, a compact and highly sensitive refractive index plasmonic sensor, with a metal-insulator–metal waveguide coupled with a notched hexagonal ring resonator and the stub is proposed. Structural parameters of the sensor have a key role in the sensor’s sensitivity and transmission spectrum, which are investigated using the finite-difference time-domain method embedded in the commercial simulator R-Soft. The results yield a linear link with the refractive index of the material under testing and its wavelength resonances. Moreover, the maximum linear sensitivity is S = 2547 nm/RIU, its corresponding sensing resolution is 3.92 × 10−6 RIU. Therefore, this sensor can be implemented in high-performance nano-sensors and bio-sensing devices. In this proposed structure, the positions of transmission peaks can be easily manipulated, by adjusting the length and width of the stub.

Ultra-high-sensitive sensor based on a metal–insulator–metal waveguide coupled with cross cavity

In this paper, a high-sensitive plasmonic sensor based on metal–insulator–metal waveguide coupled with the interesting metal nanoracetrack defects in a cross cavity is proposed and investigated. The sensing characteristics of the proposed design are analyzed by the means of finite difference time domain method which is embedded in the commercial simulator R-Soft. The positions of transmission peaks can be easily manipulated by adjusting both the radius and the distance between the centers of the two racetrack defects in the cavity. The achieved results exhibit a linear relationship between the material’s refractive indices and theirs corresponding wavelengths of resonance, whereas the obtained maximum linear sensitivity is 3410 nm/RIU which corresponds to a sensing resolution as precise as $$2.93 \times 10^{-6}$$ RIU. The proposed sensor has great impact on different technologies advancement as it can be implemented in high performance nanosensors and bio-sensing devices.

Modulation of the Transmission Spectra of the Double-Ring Structure by Surface Plasmonic Polaritons

This paper proposes a new structural design to excite surface plasmonic polaritons to enhance the double-ring interference structure. The double-ring structure was etched into a thin film to form fundamental interference patterns, and periodic concentric-ring grooves were employed to gather energy from the surrounding regions through the excitation of surface plasmonic polaritons. Accordingly, the energy of the incident light can be concentrated at the center. The surface plasmon modulates the interference pattern and the transmission spectra. The transmission peak position and its intensity can be tuned by changing the alignment of the grooves. The proposed structure can be applied for designing plasmonic devices as useful components of the plasmonic toolbox.

Design and analysis of near infrared high sensitive metal-insulator-metal plasmonic bio-sensor

In this paper, a high sensitivity metal-insulator-metal (MIM) waveguide based plasmonic sensor, coupled by a hexagonal ring resonator is proposed. The sensing characteristics of the device are analyzed by the finite-difference time-domain (FDTD) method embedded in the commercial simulator R-Soft. From results, there is a linear relation between the material’s refractive index and its wavelength resonances. Moreover, the maximum linear sensitivity is S = 1743 nm/RIU for the second mode and it is S = 836 nm/RIU for the first mode, its corresponding sensing resolution is 5.73 × 10−6 RIU for mode 2 and 1.19 × 10−5 RIU for mode 1. The proposed sensor can be implemented in high performance nano-sensors and bio-sensing devices. The positions of transmission peaks can be easily manipulated by adjusting the inner side lengths of the hexagonal ring resonator, making this structure a dynamically controllable band pass filter. In addition, introducing another small hexagonal ring within the base resonator decreased the full width of half maximum (FWHM) of the resonance peak.

Multichannel asymmetric transmission through a dimer defect with saturable inter-site nonlinearity

We consider the asymmetric transmission properties of a discrete nonlinear Schrödinger type dimer with a saturable nonlinear intersite coupling between the dimer sites, in addition to a cubic onsite nonlinearity and asymmetric linear onsite potentials. In contrast to previously studied cases with pure onsite nonlinearities, the transmission coefficient for stationary transmission is shown to be a multivalued function of the transmitted intensity, in regimes of low saturability and small or moderate transmitted intensity. The corresponding backward transfer map is analyzed analytically and numerically, and shown to have either one or three distinct solutions for saturable coupling, and zero or two solutions for the purely cubic nonlinear coupling. As saturation strength is increased, the multi-solution regimes disappear through bifurcations and the single-valued regime of the onsite model is recovered. The existence of multiple solution branches yields novel mechanisms for asymmetric left/right stationary transmission: in addition to shifts of the positions of transmission peaks, peaks for transmission in one direction may correspond to nonexistence of stationary solutions propagating in the opposite direction, at the corresponding branch and transmitted intensity. Moreover, one of these transmission channels behaves as a nearly perfect mirror for incoming signals. The linear stability of the stationary solutions is analyzed, and instabilities are typically observed, and illustrated by direct numerical simulations, in regimes with large transmission coefficient. Intersite nonlinearities are found to prevent the formation of a localized dimer mode in the instability-induced dynamics. Finally, the partial reflection and transmission of a Gaussian excitation is studied, and the asymmetric transmission properties are compared to previously studied onsite models.

A high-sensitive sensor and band-stop filter based on intersected double ring resonators in metal–insulator–metal structure

In this paper, a waveguide coupled with two intersected cavity ring resonators, based plasmonic sensor has been proposed, which is compact in design with higher sensitivity. The structural parameters of the sensor has a key role in its sensitivity and transmission spectrum, and are analyzed using the finite-difference time-domain method embedded in the commercial simulator Rsoft. The results yield a linearity between the refractive index of the material under testing and its resonance wavelengths. The maximum achieved linear sensitivity was S = 2448 nm/RIU for the second mode and S = 1120 nm/RIU for the first mode, its corresponding sensing resolution is $$4.08 \times {{10}^{-6}}$$ RIU for mode 2 and $$8.98 \times {{10}^{-6}}$$ RIU for mode 1, which makes our design a promising candidate for high performance nano-sensors and bio-sensing devices. It’s also applicable as a band-stop filter, due to the fact that the positions of transmission peaks and bandwidth can be easily manipulated, by adjusting both the inner radius and the distance between the centers of the two ring resonators.

Refractive index sensor and filter of metal-insulator-metal waveguide based on ring resonator embedded by cross structure

Continuous improvement in nanofabrication and nano-characterization capabilities have changed projections about the role that metals could play in developing the new optical devices. Surface plasmon polaritons are evanescent waves that propagate along a metal-dielectric interface. They can be laterally confined below the diffraction limit by using subwavelength metal structures, rendering them attractive to the development of miniaturized optical devices. A surface plasmon polariton refractive index sensor and filter which consist of two metal-insulator-metal (MIM) waveguides coupled to each other by a ring resonator embedded by cross structure are proposed. And the transmission characteristics of surface plasmon polaritons are studied in our proposed structure. The transmission properties of such a structure are simulated by the finite element method, and the eigenvalue wavelengths of the ring resonator are calculated theoretically. The sensing characteristics of such a structure are systematically analyzed by investigating the transmission spectrum. The results show that there are three resonance peaks in the transmission spectrum, that is, three resonance modes corresponding to the eigenvalue solutions of the first, second and third-order Bessel eigen-function equations, and each of which has a linear relationship with the refractive index of the material under sensing. Through the optimization of structural parameters, we achieve a theoretical value of the refractive index sensitivity (S) as high as 1500 nm/RIU, and the corresponding sensing resolution is 1.3310-4 RIU. More importantly, it is sensitive to none of the parameters of our proposed structure, which means that the sensitivity of the sensor is immune to the fabrication deviation. In addition, by the resonant theory of ring resonator, we find a linear relationship between the resonance wavelength and the radius of ring resonator. So the resonance wavelength can be easily manipulated by adjusting the radius and refractive index. In addition, the positions of transmission peaks can be easily modulated by changing the radius of the ring, which can be used to design band-pass filter for a large wavelength range. Moreover, the transmission intensity and the transmission bandwidth decrease as spacing distance between the MIM waveguide and ring cavity increases. These results would be helpful in designing the refractive index sensor of high-sensitivity and band-pass filters, and have guiding significance for biological sensor applications.

Tunable plasmon-induced transparency in plasmonic metamaterial composed of three identical rings

We numerically investigated the plasmon-induced transparency (PIT) effect in a three-dimensional plasmonic metamaterial composed of three identical rings. It is illustrated that the PIT effect appears as a result of the destructive interference between the electric dipole and the quadrupole resonance mode. By tuning gap distance, radius or rotation angle of the metamaterial, the required transmission spectra with a narrow sharp transparency peak can be realized. In particular, it is found that an on-to-off amplitude modulation of the PIT transparency window can be achieved by moving or rotating the horizontal ring. Two dips move to high frequency and low frequency regions, respectively, in the transmission spectra by moving the horizontal ring, namely, the width of transmission peak becomes larger. With the rotation of horizontal ring, both width and position of transmission peak are kept invariant. Our designed structure achieved a maximum group index of 352 in the visible frequency range, which has a significant slow light effect. Moreover, the PIT effect is explained based on the classical two-oscillator theory, which is in well agreement with the numerical results. It indicates our proposed structure and theoretical analysis may open up avenues for the tunable control of light in highly integrated optical circuits.

A tunable atomic line filter without sacrificing transmission based on the combination of selective pump and magnetic field

This paper presents a theoretical model of an atomic line filter based on optical anisotropy which is induced by the combination of the selective pump and an external magnetic field. By analyzing the pumping process, we carefully elucidated the influence of the selective pump and magnetic field on the pumping process, and furthermore on the tunability and peak transmission of the filter. Different from the previously reported filter, our numerical results suggest that this type of filter has a large-scale tunability at the transmission peak position without sacrificing transmission, which is very important in free-space optical communication and lidar systems subjected to large Doppler shift.

Dual-channel extraordinary ultraviolet transmission through an aluminum nanohole array

Ultraviolet (UV) surface plasmon (SP) has distinct applications in UV filters, high-density optical storage, spectral enhancement, optical detectors, and nanolithography, which are closely related to plasmon-induced extraordinary optical transmission (EOT). However, such EOT in the UV region has not been the subject of detailed research. We report UV transmission based on theoretical research using the finite-difference time-domain method, by modulating the Al thickness, hole size, array periodicity, and SiO2 overlayer thickness. It is notable that we can obtain dual-channel UV transmission peaks with excellent qualities such as high transmissivity, zero cross-talk, narrow bandwidth, and perfect symmetry, by optimizing the parameters. The UV transmission peaks have been discovered to non-monotonously shift with increasing hole size. Although array periodicity has great influence on the transmission peak position, the peak energy in the UV region is much less than the value predicted by the well-known periodicity-related surface plasmon polariton (SPP) wavelength equation; the energy discrepancy in the UV region can reach above 20%, which is much larger than the value (typically 4%) in the visible-infrared region. Furthermore, the SiO2 overlayer may significantly modify the transmission properties. The Al nanohole arrays have also been found to exhibit distinct multi-band UV electric field enhancement properties with special interface effect and size effect. Such extraordinary dual-channel UV transmission with zero cross-talk, based on a very simple Al nanohole array, has promising application in dual-channel UV filters, high-density optical storage, and plasmon-enhanced fluorescence/Raman spectroscopy, which generally involves two wavebands (writing/reading storage or exciting/emission wavelengths). This study is expected to broaden our fundamental understanding of the UV EOT phenomenon, and provide references for experimental research and application of deep-UV and near-UV-related dual-band plasmonic devices.

Bound states in one-dimensional acoustic parity-time-symmetric lattices for perfect sensing

In this letter, we study the propagation of acoustic waves through a one-dimensional multilayer structure composed of a thin defect layer sandwiched by two phononic crystals. Two kinds of defect states will generate in band gaps and both of them cause unitary transmission. However, they have very unlike field distributions due to the different contrasted acoustic impedances between the defect layer and its neighboring layers. Spectral positions of transmission peaks can be exactly determined by the resonant phase condition. In a non-dissipative system, these resonant states correspond to single crossing point of two eigenvalues of scattering matrix. When gain and loss are introduced to judiciously construct an acoustic parity-time-symmetric lattice, the crossing point will split into a pair of exceptional points (EPs). Interestingly, the EPs correspond to unidirectional zero reflection that is very sensitive to the thickness of defect layer. Taking advantage of this virtue, a very sensitive acoustic sensor can be designed, which has potentially applications in ultrasonic inspection, noise detection, ultrasonic medicine, etc.

Optical properties of Yb-doped LaB6 from first-principles calculation

The optical properties of Yb-doped LaB6 have been investigated by first-principles calculations within the framework of density functional theory. The results show that the Yb [Formula: see text] states at near Fermi surface affect their optical properties and the Yb-doping leads to a reduction of the plasmon energy of LaB6, i.e. a redshift of the position of transmission peak in the visible-near infrared region. This study offers a theoretical prediction for the design and application of Yb-doped LaB6 as an optoelectronic material.

Surface plasmon resonance sensor based at metallic subwavelength structures

Simulated transmission spectrums and the change of the transmission peak position with the refractive index by the finite-difference time-domain method are present. The considered structure is the two-dimensional metallic square hole and trapezoid hole array, and the change of the transmission peak position with the refractive index can achieve about 1000nmRIU−1. In comparison, the sensor properties of the metallic trapezoid hole array is better than that of the metallic square hole array. Meanwhile, the field intensity enhancement and localization of the metallic trapezoid hole are better. Meanwhile, these array structures can extensively apply to biochemical sensor devices design and localized field enhancement device so on.

Free‐standing aluminium nanowire arrays for high‐transmission plasmonic colour filters

Presented is a fabrication process for the transmission of red–green–blue (RGB) colour filters based on surface plasmons (SPs) using aluminium (Al) nanowire arrays patterned through electron-beam lithography and the lift-off technique. An array of Al nanowires was deployed over a through hole formed by sacrificial silicon etching. The period of the Al nanowire arrays is the dominant structural parameter in determining the transmission peak position of SPs for a given material configuration. The Al nanowire arrays are designed with the same Al wire width under the assumption of operation using a microelectromechanical systems (MEMS) comb-drive actuator for the realisation of an RGB tunable colour filter. The peak wavelength of the transmitted light was red-shifted by increasing the period of the Al nanowire arrays from 450 to 600 nm, and RGB colours were demonstrated. A black pixel was produced using the 400 nm pitch Al nanowire array. The maximum measured transmittance of the peak wavelength was 56%. In addition, the number of nanowires sufficient for low-power operation by a MEMS comb-drive actuator was investigated and sufficient transmission light intensity was obtained from the pixel size of 10 µm2, including 20 Al nanowires.

Analysis of phase shift of surface plasmon polaritons at metallic subwavelength hole arrays

We present the transmission spectra of light transmitting a metallic thin film perforated with differently shaped subwavelength hole arrays, which are calculated by a plane-wave-based transfer matrix method. We analyze the transmission peak positions and the phase-shift angles of different surface plasmon polariton (SPP) modes by using the microscopic theoretical model proposed by Haitao Liu and Philippe Lalanne [Liu Haitao and Lalanne Philippe 2008 Nature 452 728], in which the phase shift properties of the SPPs scattered by the subwavelength hole arrays are considered. The results show that the transmission peak position and the minus phase shift angle of the SPP increase as the hole size increases. On the other hand, the effective dielectric constant of the metallic film can be deduced by the microscopic theoretical model.

A New Plasmonic Filter through Double Metal Films Perforated with Rectangular Grooves and Circular Holes

A novel plasmonic passband filter consisting of metal-insulator-metal perforated with an array of rectangular grooves and circular holes is proposed and demonstrated. The transmission property of the proposed structure is obtained by employing the finite difference time domain with perfectly matched layer absorbing boundary condition. The result reveals that a passband with high transmission can be achieved. And the transmission peak position can be efficiently tuned by changing the factors of the structure, such as the sizes of circular holes and grooves. The proposed filter has potential applications for integrated optoelectronic devices due to its miniaturized size.

Comparisons of two subwavelength aperture arrays with different lattice structure for light transmission

The transmission through subwavelength square and hexagonal lattice structure hole arrays in aluminum films at mid-infrared spectral range is reported experimentally in this work. Enhanced transmission peak is observed at wavelengths up to seven times of the hole's diameter. Positions of the transmission peaks are coincide with the prediction of surface plasmon polaritons (SPPs) theory. Lattice structure is proved to be a decisive factor of the transmission spectra. Interface media on both sides of the metal structure also affect the transmission peak position. These results are meaningful for the aperture applications in infrared detection and frequency selective surfaces devices.

Study on optical switching effect of photonic crystals with negative effective index of refraction

Based on transmission spectra, optical switching effect of equivalent negative refractive photonic crystals (PCs) composed of a triangular array of air cylinders in a GaAs matrix is studied by the finite-difference time-domain (FDTD) method in this paper. The mechanism of wave resonance is probed and the propagation of optical waves in the PCs is described in terms of effective refraction index and Bloch waves. Our numerical results show that the probability of spontaneous radiation would be enhanced extremely under the influence of Bloch resonance waves, stimulated emission and photon tunnel effect, resulting in the optical waves being localized greatly in the PCs at particular frequencies. In addition, we found that the position of transmission peaks, with values much greater than unit, can be controlled by tuning the central frequency of the waveguide source. It means that photon current in the PCs can also be controlled to optimize transmission properties of PCs, so as to meet the requirements of novel optical devices based on PCs, such as all-optical switches.