INVESTIGATION OF THE SURFACE PLASMON-POLARITONS EXCITATION EFFICIENCY ON ALUMINUM GRATINGS, TAKING INTO ACCOUNT DIFFRACTED RADIATION

2021 ◽  
Vol 56 ◽  
pp. 71-82
Author(s):  
I. Z. Indutnyi ◽  

Detailed studies of the efficiency of excitation of surface plasmon-polaritons (SPP) on aluminum gratings with a period a = 694 nm, which exceeds the incident wavelength of λ = 632,8 nm, have been carried out. The gratings relief depth (h) range was 6–135 nm. Research samples were formed on As40S30Se30 chalcogenide photoresist films using interference lithography and vacuum thermal deposition of an opaque aluminum layer about 80 nm thick. An atomic force microscope was used to determine the groove profile shape and the grating relief depth. The study of the SPP excitation features was carried out on a stand mounted on the basis of a G5M goniometer and an FS-5 Fedorov stage by measuring the angular dependences of the intensity of specularly reflected and diffracted p-polarized radiation of He-Ne laser. When determining the SPP excitation efficiency, the resonance values of both specular reflection and reflection in the -1st DO were taken into account. It was found that the dependence of the integral plasmon absorption on the grating modulation depth (h/a) is described by a somewhat asymmetric curve with a wide maximum, the position of which corresponds to an h/a value of about 0.07 and a half-width of about 0.123. This allows to excite SPP with an efficiency ≥ 80% of the maximum value on the gratings with the 0,05-0,105 h/a range. The half-width of the plasmon minimum of the reflection in the -1st DO is less than in the specular reflection, which can increase sensitivity of sensor devices when registering the shift of the minimum from angular measurements. The dependence of the half-width of the SPP reflection minima on the grating modulation depth is close to quadratic. In the investigated h/a range (from 0.009 to 0.194), the maximum dynamic range of the reflection coefficient is two orders of magnitude and is achieved in specular reflection for gratings with h/a ≈ 0.075.

2020 ◽  
Vol 55 ◽  
pp. 117-125
Author(s):  
I.Z. Indutnyi ◽  

An experimental study of the excitation of surface plasmonpolaritons (SPP) on aluminum diffraction gratings with a fixed period of 519 ± 0,5 nm and a variable modulation depth h/a(where h is the grating depth, and a – its period) was carried out. Gratings with a sine-like profile were formed on vacuum chalcogenide photoresists films by interference lithography and covered with an opaque aluminum film. A Dimension 3000 Scanning Probe Microscope was used to determine the grating groove profile. The characteristics of the SPP were determinedfor28 gratings with h/a ranged from 0,018 to 0,20, by measuring the dependences of specular reflection of p-polarized radiation of He-Ne laser on the angle of incidence, which was defined as the angle between the normal to the substrate plane and the laser beam. It was found that there is an optimal grating relief depth for a given excitation wavelength, which provides the maximum transfer of the incident electromagnetic wave energy to the surface plasmon-polariton mode.The dependence of the SPP excitation efficiency on the grating modulation depth has a maximum at a relatively small value of h/a ≈ 0.086. At such modulation depth the absorption of electromagnetic radiation of the incident laser beam is more than two orders of magnitude higher than the absorption of aluminum film with flat surface at the same angle of incidence. The position of the angle of resonant excitation of SPP practically does not change from h/a= 0,018 up to h/a ≈ 0,06. With further increase of h/a it begins to shift to the region of smaller incidence angles, with the rate of the shift accelerating gradually. With an increase of h/a, a decrease in the depth of the plasmon resonance and a significant increase in its half-width are also observed, and the dependence of the half-width of the SPP band on the modulation depth is close to quadratic. Using this grating-coupled SPP technique, the estimated thickness of air-formed oxide layer on the aluminum gratings surface (about 3.9 nm) is close to the value obtained in the literature with a set of complicated techniques.


2021 ◽  
Vol 24 (04) ◽  
pp. 436-443
Author(s):  
I.Z. Indutnyi ◽  
◽  
V.I. Mynko ◽  
M.V. Sopinskyy ◽  
V.A. Dan’ko ◽  
...  

The effect of surface plasmon-polaritons (SPPs) excited at the interface between the profiled surface of the silver layer (in the form of a diffraction grating) and the As4Ge30S66 layer on the photostimulated diffusion of silver into chalcogenide has been studied. The gratings with the period a = 519 nm and modulation depth h/a ≈ 0.037 (where h is the grating depth) were formed on chalcogenide photoresist films by using interferential lithography and covered with the 80-nm-thick aluminum layer, 85-nm-thick silver layer, and thin As4Ge30S66 layer. Photostimulated changes in this structure were studied measuring the angular dependences of specular reflection (Rp) of p-polarized light with the wavelength 632.8 nm. It was found that as a result of exposure, “degradation” (broadening, increase in reflection at the minimum) of the minimum in the angular dependence of Rp (which is associated with the SPP resonance) occurs faster, when the samples are irradiated at the angle corresponding to SPP excitation. This observation indicates acceleration of the photostimulated diffusion process in this structure under the plasmon field action.


Sensors ◽  
2018 ◽  
Vol 19 (1) ◽  
pp. 89 ◽  
Author(s):  
Ming Cai ◽  
Shulong Wang ◽  
Bo Gao ◽  
Yindi Wang ◽  
Tao Han ◽  
...  

In this paper, a new electro-optical switch modulator based on the surface plasmon polaritons of graphene is proposed. An air–graphene-substrate–dielectric structure is adopted in the modulator. In this structure, the graphene is considered as a film of metal whose thickness tends to be infinitesimal. By changing the external voltage, the boundary conditions can be changed to decide whether the surface plasmon polariton waves can be excited in mid-infrared band. Because of this effect, the structure can be used as an electro–optical switch modulator, whose modulation depth is about 100% in theory. Finally, the 3 dB bandwidth (~34 GHz) and the energy loss (36.47 fJ/bit) of the electro–optical switch modulator are given, whose low energy loss is very suitable for engineering applications.


Author(s):  
Riyadh D. Mansoor ◽  
Alistair Duffy

Surface Plasmon Polaritons (SPPs) are propagating excitations that arise from the coupling of light with collective oscillations of electrons on the metal surface. This paper describes a new approach for increasing the SPP excitation efficiency. Using a computational electromagnetics approach, potential techniques for reducing incident power reflectivity were investigated using the Kretschmann configuration. The effects of different parameters such as incident angle, metal thickness, and dielectric permittivity were tested and optimized to improve the efficiency of SPPs by minimizing reflectivity. An 30% increase in efficiency was obtained. In addition, the optical response of a thin metal film on a glass substrate was numerically examined in terms of SPP excitation. The dependency of the response on the incident angle, materials, and dimensions were demonstrated. This paper describes how an improvement in efficiency can improve the effectiveness of bio-sensing applications through the proper choice of layer dimensions and material permittivity of different layers. The relationship between incident angle and reflectivity for different permittivities can be used for bio-sensing applications such as blood glucose biosensors, etc.


Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2757 ◽  
Author(s):  
Phitsini Suvarnaphaet ◽  
Suejit Pechprasarn

In this paper, we report a theoretical framework on the effect of multiple resonances inside the dielectric cavity of insulator-insulator-metal-insulator (IIMI)-based surface plasmon sensors. It has been very well established that the structure can support both long-range surface plasmon polaritons (LRSPP) and short-range surface plasmon polaritons (SRSPP). We found that the dielectric resonant cavity under certain conditions can be employed as a resonator to enhance the LRSPP properties. These conditions are: (1) the refractive index of the resonant cavity was greater than the refractive index of the sample layer and (2) when light propagated in the resonant cavity and was evanescent in the sample layer. We showed through the analytical calculation using Fresnel equations and rigorous coupled wave theory that the proposed structure with the mentioned conditions can extend the dynamic range of LRSPP excitation and enhance at least five times more plasmon intensity on the surface of the metal compared to the surface plasmon excited by the conventional Kretschmann configuration. It can enhance the dip sensitivity and the dynamic range in refractive index sensing without losing the sharpness of the LRSPP dip. We also showed that the interferometric modes in the cavity can be insensitive to the surface plasmon modes. This allowed a self-referenced surface plasmon resonance structure, in which the interferometric mode measured changes in the sensor structure and the enhanced LRSPP measured changes in the sample channel.


2011 ◽  
Vol 181 (3) ◽  
pp. 305 ◽  
Author(s):  
V.B. Zon ◽  
B.A. Zon ◽  
V.G. Klyuev ◽  
A.N. Latyshev ◽  
D.A. Minakov ◽  
...  

2020 ◽  
Vol 14 (1) ◽  
pp. 015002
Author(s):  
Xinguang Hu ◽  
Cheng Zeng ◽  
Jinsong Xia ◽  
Yunji Meng

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