In this paper, we theoretically demonstrate a polarizing filter consisted of graphene ribbon arrays with varying width placed on the top surface of dielectric and a metal reflector rested at the bottom of the structure. It is found that proper ribbon width, which corresponds to resonant frequency of graphene plasmons, is a crucial factor that can significantly influence the absorption effect. The results of fullwave numerical simulations indicate that total absorption of more than 90% for TE polarization and approaching to 1% for TM polarization can be achieved at normal incidence in the infrared range. Therefore, this characteristic can be applied into polarizing filter by adjusting the coupling effect between the graphene ribbon arrays. Such structure will be beneficial to the manufacture of infrared nano-photonic devices for optical filtering and selective absorption.
A novel and simple multi-wavelength band-pass filter based on
metal-insular-metal (MIM) waveguide with different nanodisk cavity is proposed and
investigated numerically by Finite-Element-Method (FEM) simulations. According to
resonant theory of nanodisk, multi-wavelength band-pass filter can be achieved for
different wavelength. It also shows that the transmission characteristics of the filter and
the resonant wavelength can be easily manipulated by changing the gap between
nanodisk and straight waveguide or changing the radius of the nanodisk. This kind of
plasmonic waveguide filter may become important promising application in highly
plasmonic integrated circuits.
A nonlinear hybrid plasmonic waveguide (HPW) with a metal cap on a nonlinear material-on-insulator rib is proposed. By using a finite-difference time-domain method, its light confinement and effective nonlinearity coefficient of the Kerr effect for all-optical switches are analyzed in detail. Numerical simulations illustrate that the nonlinear HPW structure has nanoscale confinement and high effective nonlinearity coefficient at the wavelength of 1550 nm. Consequently, the HPW can be used in all-optical signal processing of integrated photonics.
In order to improve integration density, it is essential to develop a nano-scale optical waveguide
which is the key element to build varies of optical components. In this paper, a novel cylindrical hybrid
plasmonic waveguide, which has an air core surrounded by a metal layer and a silicon layer, is
proposed to achieve nano-scale confinement of light at the operating wavelength of 1550nm. And there
is a low-index material nano-layer between the metal layer and the silicon layer, in which the field
enhancement provides a nano-scale confinement of the optical field. The relations between the
characteristics of the bound modes, including the effective mode indices, propagation lengths, mode
sizes, mode shapes and parameters of the plasmonic waveguide are numerically investigated in detail.
The simulation results show that the nano-scale confinement can be realized and the proposed hybrid
plasmonic waveguide has a potential application in high density photonic integration.
Keywords: Surface Plasmon, Mode confinement, Subwavelength structure
The special abilities of plasmonic waveguide including tight field confinement and beyond diffraction limit within nano-scale structure have been exploited in many different fields. In order to overcome the trade-off between tight mode confinement and long propagation length, many kinds of nano-scale structures have been proposed in recent years. In this paper, a novel hybrid plasmonic waveguide consisting of the layer of metal Ag, a spherical cap with low-index dielectric layer placed above the metal Ag and a high-index dielectric layer placed above the spherical cap is proposed and analyzed theoretically. The relations between the characteristics of the bound modes, such as mode confinement, propagation lengths, and parameters of the spherical cap, the curvature and width, are numerically investigated in detail. The simulation results show that the nano-scale confinement can be realized. The simulation result shows that the performance of the proposed spherical cap hybrid plasmonic waveguide is better than the rectangle or cylindrical hybrid plasmonic waveguide. Such hybrid plasmonic waveguide has a tight mode confinement and long propagation length. This novel structure provides a promising application for high-integration density photonic components.
This article deals with designing broadband and high efficiency metal multi-layer dielectric grating (MMDG) used to
compress and stretch ultra-short laser pulse. The diffraction characteristics of MMDG are analyzed with the method of
rigorous coupled-wave analysis (RCWA). Taking the diffraction efficiency of the -1 order as the value of merit function,
the parameters such as groove depth, residual thickness, duty cycle are optimized to obtain broadband and high
diffraction efficiency. The optimized MMDG shows an ultra-broadband working spectrum with the average efficiency
exceeding 97% over 135nm wavelength centered at 800nm and TE polarization. The optimized MMDG should be useful
for chirped pulse amplification.
The purpose of this study is dedicated to the new design of the Multi-layer dielectric grating with the best performance
giving a highly diffraction efficiency in the -1 order, by using the rigorous coupled wave Analysis (RCWA). The
formulation for the implementation of the RCWA for multi-layer dielectric gratings incorporating the developed
enhanced transmittance approach is presented. An optimized design of multi-layer dielectric grating working at 1053-nm with TE polarized light and 51.2° incident can obtain the diffraction efficiency of 99%.
The optical property of multi-layer dielectric thin film is determined by its operation on the more or less complete
cancellation of the light reflected at the upper and lower of the multi-layer interface of the thin film. An enhanced,
numerically stable transmittance matrix approach based on rigorous coupled-wave analysis (RCWA) is applied to the
analysis of optical character for multi-layer dielectric thin film. A design of a thin film stack used in multi-lay dielectric
grating was presented by using the method of RCWA. The numerical calculation shows that RCWA is a relatively
straightforward and deterministic technique for analysis the optical property of multi-layer dielectric thin film.
Superresolution plays an important role in the super high-density optical storage systems. With the superresolution technology the storage capacity can be increased by the decrease of the Airy spot. General the optical superresoluiton is realized by inserting the conventional superresolution pupil filters in the optical system. But there lies an obvious limitation in the conventional pupil filters. It is that once the pupil filter is fabricated, the corresponding superresolution characteristics can not be changed. In order to overcome this drawback, a new set of pure phase filters for realizing the tunable transverse superresolution is presented in this paper. The filters, whose significant feature are their ability to tune and simplicity, consist of one half-wave plate between of two quarter-wave plates, and the half-wave plate is made of two zones that can rotate with respect to each other. By rotating any zone of the half-wave plate, the central lobe width of the irradiance point spread function (PSF) in the transverse direction can be tunable reduced.
Reactive magnetron sputtering can be used to prepare graded index coatings. In this paper the relationship between the refractive index of the coatings and the partial pressure of reactive gas is discussed by experiment, in which A, O2 and Si are taken as sputtering gas, reactive gas and target material separately. And we have come to such conclusions that with the increase of partial pressure of reactive gas the color of the coatings turns shoal, the transmittance minimum of the coatings increases and the refractive index of coatings decreases according to the fitting rule of cubic polynomial. From XRD analysis, it can be seen that the coatings are identified to be amorphous.
Multi-layer dielectric grating is a key element used in chirped-pulse amplification technique. It includes high reflectivity film and periodic gratings on its top. Design of HR coating and top layer film (called multi-layer dielectric grating film) to produce gratings is important to fabricate such element with perfect optical properties and high laser induced damage threshold. In this paper, needle method is employed to synthesize the HR film with non-quarter wave coatings. The top layer is constructed by Fourier modal method, which is a rigorous method to analyze gratings. The synthesized multi-layer dielectric grating film shows good optical properties and electric intensity distribution.
By introducing scattering probability and statistical distribution functions of substrate subsurface defects' radius, refractive indices and positions, extended bidirectional reflectance distribution function (BRDF) was derived on the foundation of Jones scattering matrix. A numerical calculation of the extended BRDF for p-polarization incident light has been performed by employing Monte Carlo method. The calculating results indicate that the extended BRDF depends strongly on incident angle, scattering angle and azimuth angle, and presents a specific symmetry. For real refractive index, the extended BRDF is independent of subsurface defects' positions. And the extended BRDF will provide a more precise model for the calculation and measurement of polarized light scattering resulting from subsurface defects.
Multi-layer dielectric gratings (MDG) have been more and more used in the chirped-pulse amplification (CPA) system because of its higher diffraction efficiencies and higher damage threshold, which is compared with metallic gratings. Design parameter of multi-layer dielectric and gratings are both given. Laser-induced damage threshold (LIDT) of MDG has been test by employing 1-on-1 methods. The result is 3.24J/cm2 at 1064nm and 12ns pulselength (51.2° incidence). The mechanics of damage is also discussed in several ways.