We propose a metamaterial with a three-layer structure based on Faraday's law. The metamaterial is simply formed by a pair of homogeneous parallel plates separated by a thin medium. We also propose a virtual current loop with length of 2a ͑a is the attenuation constant͒ in the plates, which can be formed upon excitation of an electromagnetic field. Strong magnetic response has been observed by spectroscopic ellipsometry and the resonant frequency can be widely tuned by varying the structure dimensions. The observations are also verified by optical transfer matrix. The easy fabrication and high interfacial quality of the structure will make the applications of the magnetic response and negative refractive index metamaterials a reality.In 1968, Veselago conceived of a material whose index of refraction could be negative with both a negative permittivity and a negative permeability, which would reverse nearly all known optical phenomena. 1 Such material has not been realized until recent years when the artificially structured materials, or metamaterials, were reported. 2 These metamaterials open the door to a variety of physical phenomena and potential applications. [3][4][5] A negative permittivity is not unusual and occurs in any metal from zero frequency to the plasma frequency. However, a negative permeability, which means a negative magnetic response, at optical frequencies does not occur in natural materials.At present, a popular magnetic metamaterial has been formed from a periodic array of nonmagnetic, conducting, split-ring resonators ͑SRRs͒, achieved in essence just by mimicking a small LC circuit structure of eigenfrequency LC with LC = ͑LC͒ −1/2 . Each SRR structure consists of a magnetic coil with inductance L and a capacitor with capacitance C. 6-9 Since the first demonstration at microwave frequencies, 10 the achieved magnetic resonance frequencies have been increased by more than four orders of magnitude over the last few years, 6-8 reaching a record of 370 THz ͑800 nm wavelength͒ in 2005. 9 The structure of the metamaterials currently studied needs to be as fine as possible. 4 A variety of potential applications, including higher resolution optical imaging and nanolithography, will be limited by the complexity of the SRR structures. For example, a superlens, one of the most desirable applications in the negative refractive index, at optical wavelengths requires the structure being extremely smooth with a surface roughness less than 1 nm. Otherwise, the surface imperfections would scatter the incident light and wash out the finer details carried by the evanescent waves. 4,11 Another issue regarding the practicality of the present metamaterials is their complicated electromagnetic response, which makes their utilization as devices complicated and a full electromagnetic characterization difficult. 12 Furthermore, to improve the oscillator strength of the magnetic resonance, the number of SRR per unit area should be high enough. 9 This is limited by the capability of manufacture. Therefore, there is a s...
In this paper we present an extensive theoretical and numerical analysis of monolithic high-index contrast grating, facilitating simple manufacture of compact mirrors for very broad spectrum of vertical-cavity surface-emitting lasers (VCSELs) emitting from ultraviolet to mid-infrared. We provide the theoretical background explaining the phenomenon of high reflectance in monolithic subwavelength gratings. In addition, by using a three-dimensional, fully vectorial optical model, verified by comparison with the experiment, we investigate the optimal parameters of high-index contrast grating enabling more than 99.99% reflectance in the diversity of photonic materials and in the broad range of wavelengths.
InSbN alloys are fabricated by two-step nitrogen ion implantation into InSb (111) wafers. X-ray photoelectron spectroscopy indicates that most of the implanted nitrogen ions substitute Sb to form In–N bonds. The percentage of the In–N bonds is found to decrease with the increase in the implanted nitrogen. Such alloys can effectively detect long wavelength infrared radiation and the absorption peak energies can be controlled by monitoring the implanted nitrogen dose. The measured peak wavelengths are consistent with the band gaps of the alloys calculated using a ten-band k⋅p model.
We demonstrate an experimental result that shows the phase singularity of surface plasmon waves generated by the direct transform of optical vortices at normal incidence focused on a structureless metal surface. The near-field two-dimensional intensity distribution near the focal plane is experimentally examined by using near-field scanning optical microscopy and shows a good agreement with the finite-difference time-domain simulation result. The experimental realization demonstrates a potential of the proposed excitation scheme to be reconfigured locally with advantages over structures milled into optically thick metallic films for plasmonics applications involving plasmonic vortices.
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