JP2003302336A - Method and element for signal processing by surface plasmon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method in which a change in a signal of a surface plasmon is signal-processed as a change in a synchrotron radiation and to obtain a signal processing element by using the method. <P>SOLUTION: In the method for processing the signal by the surface plasmon, a dielectric layer 2 is arranged on a metal thin film 1, an optical coupler composed of a light transmission medium 3 is arranged on its opposite side, a single or multiple surface plasmon is excited in an interface between the dielectric layer 2 and the metal thin film 1 by using an excitation light source 4 and an excitation light source 5, the signal of the surface plasmon is changed due to a change in the dielectric layer 2, and the signal is processed by using the change in the synchrotron radiation due to the resonance of the changed surface plasmon with the optical coupler. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling surface plasmons that are excited and propagated on a metal surface and use them for signal processing as a change in emitted light, and a signal processing element that can be used as a signal processing device. is there.

[0002]

2. Description of the Related Art In principle, an optical element using far-field light cannot be constructed as an element smaller than the wavelength of light used, and a small optical element using near-field light is considered. However, since the near-field light is localized near the surface of the material, a device or the like for observing and utilizing it is needed.

In addition, a dielectric layer is arranged on a metal thin film, and a prism is arranged on the opposite side of the metal thin film. When multiple surface plasmons are excited at the interface between the dielectric layer and the metal thin film by irradiation of laser light, surface plasmons It is possible to observe the synchrotron radiation on the prism side.

Therefore, a dielectric layer is arranged on the metal thin film,
An optical coupler consisting of a light-transmitting medium is arranged on the opposite side, and a single or multiple surface plasmons are excited at the interface between the dielectric layer and the metal thin film by using an excitation light source to propagate on the metal thin film. When the signal change of the surface plasmon due to the change of the body layer can be obtained as the change of the radiated light through the optical coupler of the arrangement, there is a possibility that the signal processing element can be constructed using this.

Here, when the thickness of the metal thin film in contact with the dielectric layer is made thicker to the light wavelength in air corresponding to the frequency of the surface plasmon to be handled, when no light transmitting medium is provided or when the light transmitting medium is used. When the refractive index is about 1, the surface plasmon is not excited, or even if it is excited, it is impossible to obtain a signal of radiated light from the light transmission medium.

In view of such circumstances, the present invention excites and propagates single or multiple surface plasmons at the interface between the dielectric layer and the metal thin film, and radiates the signal change of the surface plasmon due to the change of the dielectric layer. It is an object of the present invention to provide a method and a signal processing element for processing a signal as a change in the signal.

[0007]

The gist of the present invention will be described with reference to the accompanying drawings.

A dielectric layer 2 is arranged on the metal thin film 1, an optical coupler made of a light transmitting medium 3 is arranged on the opposite side, and an interface between the dielectric layer 2 and the metal thin film 1 is formed by using excitation light sources 4 and 5. A single or multiple surface plasmons are excited to propagate on the metal thin film 1, the signal of the surface plasmon is changed by the change of the dielectric layer 2, and the radiated light change due to the resonance of the changed surface plasmon and the optical coupler is changed. The present invention relates to a signal processing method using surface plasmons, which is characterized by using signals.

Further, the dielectric layer 2 is arranged on the metal thin film 1, and the optical coupler consisting of the light transmitting medium 3 is arranged on the opposite side, and the dielectric layers 2 are formed by using the excitation light sources 4 and 5. Single or multiple surface plasmons are excited at the interface of the metal thin film 1 to propagate on the metal thin film 1, and the signal change of the surface plasmon due to the change of the dielectric layer 2 is radiated through the optical coupler of the above-mentioned arrangement 6 The present invention relates to a signal processing element using surface plasmons, which is characterized in that it is obtained from the change of

A metal thin film 1 in contact with the dielectric layer 2 is also provided.
Of the surface plasmon to be handled is thinned to about 1/50 to 1/50 of the wavelength of light, and the light transmission medium 3 is placed on the side opposite to the dielectric layer 2 with the metal thin film 1 interposed therebetween. , The surface plasmon that is excited and propagated at the interface between the dielectric layer 2 and the metal thin film 1 is changed by the change of the dielectric layer 2, and the signal change of the surface plasmon can be obtained as a radiant light change. The present invention relates to a signal processing method and a signal processing element by surface plasmon according to any one of claims 1 and 2, wherein a coupler is configured.

The metal thin film 1 is an aluminum layer, the dielectric layer 2 thereon is a polyvinylcarbazole layer 2 in which a cyanine dye is dispersed, and the light transmission medium 3 on the opposite side is a semi-cylindrical prism made of BK7 glass. , The thickness of the aluminum thin film 1 is 1/50 to 1/50 of the excitation light wavelength.
The surface plasmon is excited and propagated at the interface between the metal thin film 1 and the dielectric layer 2, and the change of the dielectric layer 2 makes it possible to obtain the change of the radiated light 6 through the optical coupler. The present invention relates to a signal processing method and a signal processing element according to claim 3, wherein the optical coupler is configured as described above.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention (how to carry out the invention) will be briefly described with reference to the drawings and showing its function and effect.

The inventor of the present invention reduces the thickness of the metal thin film 1 in contact with the dielectric layer 2 to about 1/50 to 1/50 of the light wavelength corresponding to the frequency of surface plasmons to be handled. The light transmission medium 3 is placed on the opposite side of the dielectric layer 2 and the surface plasmon propagating at the interface of the dielectric layer 2 and the metal thin film 1 at almost the speed of light is changed by the change of the dielectric layer 2 and changed. It was found that the signal change of the surface plasmon can be obtained as the radiant light change. The present invention has been made based on such knowledge.

That is, in the invention described in claim 1, single or multiple surface plasmons are excited at the interface between the dielectric layer 2 and the metal thin film 1 by using the excitation light sources 4 and 5, so that the light on the metal thin film 1 is almost emitted. The signal processing is performed by changing the intensity of the radiated light 6 and the emission angle of the radiated light 6 due to the resonance of the changed surface plasmon and the optical coupler, or the change of the spectrum wavelength. It's about how to do it.

In the second aspect of the present invention, the excitation light sources 4 and 5 are used to excite single or multiple surface plasmons on the metal thin film 1 to propagate the surface plasmons on the metal thin film 1, and the dielectric layer 2 The present invention relates to a signal processing element which obtains a signal change of surface plasmon due to the change of the above from the change of the emitted light 6 through the optical coupler.

Further, in the inventions of claims 3 and 4, the metal thin film 1 is, for example, an aluminum layer, and the dielectric layer 2 thereon is a polyvinylcarbazole layer 2 in which, for example, a cyanine dye is dispersed.
The light transmission medium 3 on the opposite side is, for example, a semi-cylindrical prism made of BK7 glass, and the thickness of the aluminum layer is set to about 1/10 to 1/50 of the excitation light wavelength, and the dielectric layer 2 is formed.
The present invention relates to a method and a signal processing element for performing signal processing by changing the surface plasmon excited and propagating at the interface between the metal thin film 1 and the metal thin film 1 by a change in the dielectric layer 2 and obtaining the change as radiated light from the optical coupler. .

According to the first aspect of the invention, single or multiple surface plasmons are excited at the interface between the dielectric layer 2 and the metal thin film 1 by the excitation light sources 4 and 5, and propagate on the metal thin film 1 to form the dielectric layer. By changing 2, the surface plasmon changes, and the radiated light 6 changes due to the resonance of the surface plasmon and the optical coupler.

In the second aspect of the invention, for example, the metal thin film 1 having a thickness of about 10 to 1/50 of the light wavelength of the excitation light sources 4 and 5, the dielectric layer 2 thereon, and the light on the opposite side thereof. In the optical coupler composed of the transmission medium 3, the surface plasmon excited and propagating on the metal thin film 1 is changed by the change of the dielectric layer 2, so that the emission angle dependence of the emitted light 6 through the optical coupler is changed. To do.

[0019]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a signal processing method and a signal processing element according to the present invention. 1 is a metal thin film, for example, an aluminum thin film having a thickness of about 15 nm, and 2 is a dielectric layer. For example, a polyvinylcarbazole layer in which a cyanine dye is dispersed, 3 is a light transmitting medium, for example, a semi-cylindrical prism made of BK7 glass and having a radius of 10 nm, 4
Is an excitation light source through the light transmitting medium, for example, a wavelength of 48
An 8 nm argon laser, 5 is an excitation light source for directly exciting the dielectric layer, for example, an argon laser having a wavelength of 488 nm, 6 is a signal-processed emitted light, and 7 is an example of an emission angle.

The aluminum thin film 1 is necessary for surface plasmon excitation, and it is difficult to obtain strong excitation of the surface plasmon and strong synchrotron radiation 6 when the thickness thereof is about 8 nm, which is half, or about 30 nm, which is twice the thickness. When a silver thin film or a gold thin film is used instead of the aluminum thin film 1, the optimum film thickness for exciting the surface plasmon and obtaining the emitted light 6 is about 50 nm.
And the thickness of the silver thin film and the gold thin film is half, about 25 nm or 2
It is difficult to obtain the strong excitation of the surface plasmon and the strong radiated light 6 when the wavelength is about 100 nm.

The polyvinylcarbazole layer 2 in which the cyanine dye is dispersed functions as a dielectric layer, and surface plasmons are excited and propagated at the interface between the metal thin film 1 and the polyvinylcarbazole layer 2 in which the cyanine dye is dispersed, and the polyvinyl in which the cyanine dye is dispersed. FIG. 2 shows an example of the change of the radiated light 6 caused by the change of the surface plasmon when the carbazole layer 2 is heat-treated, and the dielectric layer 2 excites the surface plasmon and changes the propagation characteristics so that the metal thin film 1 can be changed. Place it on top.

The light transmitting medium 3 made of BK7 has a refractive index of 1.5.
By disposing the metal thin film 1 on the opposite side of the dielectric layer 2 at 2, the surface plasmon is excited and propagated at the interface between the dielectric layer 2 and the metal thin film 1 by using the excitation light source 4. The radiant light 6 from is obtained.

In FIG. 2 of the embodiment, the polyvinylcarbazole layer 2 in which the cyanine dye is dispersed is used as the dielectric layer 2, but the dielectric layer whose structure and dielectric characteristics are changed by heat treatment regardless of the organic / inorganic substance. 2 may be used, or the dielectric layer 2 whose structure and dielectric characteristics are changed by light irradiation may be used, or the dielectric layer 2 whose dielectric characteristics are changed by an electric signal.
Alternatively, the dielectric layer 2 that adsorbs gas, liquid, or solid substance may be used.

The dielectric layer 2 does not have to be layered, and may be island-shaped or spherical, and it is not necessary to completely cover the metal thin film 1, and a portion that excites surface plasmons and a portion where surface plasmons propagate, Different dielectrics may be used in the portion for obtaining the emitted light 6.

The optical coupler is composed of the metal thin film 1 and the dielectric layer 2 of FIG. 1 and the light transmitting medium 3. The light transmitting medium 3 does not need to be a semi-cylindrical prism of BK7, and an excitation light source. When 4 is used, it is sufficient if the surface plasmon can be excited by this configuration, and it is sufficient that the radiated light 6 due to the surface plasmon can be obtained. For example, even a transparent plastic material having a refractive index higher than 1 and capable of transmitting light can be used. Other glass materials may be used, and the shape does not have to be a semi-cylindrical shape, and may be a rectangular parallelepiped shape, a hemispherical shape, a triangular prism shape, or a large number of such shapes may be arranged on a light-transmitting plate. Different optical couplers may be used on the side of the emitted light 6 and on the side of the emitted light 6.

When introducing the excitation laser light from the excitation light source 4 or the excitation light source 5 and further deriving the emitted light 6, an optical fiber may be used.

The present invention is not limited to this embodiment, and the specific constitution of each constituent element can be designed as appropriate.

[0029]

Since the present invention is configured as described above, the invention according to claim 1 according to the present invention uses an excitation light source to form single or multiple surface plasmons at the interface between the dielectric layer and the metal thin film. Since it is excited and propagated on the metal thin film, the signal of the surface plasmon is changed by the change of the dielectric layer, and the signal processing can be performed as the change of the emitted light due to the resonance of the changed surface plasmon and the optical coupler. This is a method of signal processing by surface plasmon that can perform multiple signal processing at a speed corresponding to changes in body layers.

Further, in the invention described in claim 2, single or multiple surface plasmons are excited at the interface between the dielectric layer and the metal thin film to propagate on the metal thin film, and the signal of the surface plasmon due to the change of the dielectric layer is generated. The signal processing element is a surface plasmon that can form a signal processing element that changes the signal of emitted light.

According to a third aspect of the present invention, the thickness of the metal thin film in contact with the dielectric layer is reduced to about 1/50 to 1/50 of the light wavelength corresponding to the frequency of surface plasmons to be handled, and the dielectric layer is reduced. The signal processing method and signal by the extremely excellent surface plasmon that arranges the light transmission medium 3 that makes it possible to obtain a signal change of the surface plasmon due to the change of It becomes a processing element.

In the invention according to claim 4, the metal thin film is an aluminum layer, the dielectric layer thereon is a polyvinylcarbazole layer in which a cyanine dye is dispersed, and the light transmitting medium 3 on the opposite side is made of BK7 glass. Since the semi-cylindrical prism is arranged, the signal processing method and the signal processing element by the surface plasmon that can more surely obtain the change of the radiated light through the optical coupler by the change of the dielectric layer.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory diagram of the present embodiment.

FIG. 2 shows a polyvinylcarbazole layer in which a cyanine dye of the present example is dispersed functions as a dielectric layer, and radiated light before and after heat treatment of the dielectric layer when multiple surface plasmons are excited by using a direct excitation laser. Is a graph showing an example of a change in the radiation angle vs. the radiation intensity, and the radiation intensity at a radiation angle of about 50 degrees is strong after the thick line heat treatment.

[Explanation of symbols]

1 Metal thin film (aluminum thin film) 2 Dielectric layer (polyvinylcarbazole layer) 3 Light transmission medium 4 Excitation light source 5 Excitation light source 6 Synchrotron radiation

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazunari Shinbo             8050 2 Igarashi, Niigata City, Niigata Prefecture 8050 Niigata University             Faculty of Engineering (72) Inventor Takahiro Kawakami             8050 2 Igarashi, Niigata City, Niigata Prefecture 8050 Niigata University             Faculty of Engineering F term (reference) 2G059 EE01 EE02 GG01 GG03 HH02                       HH06 JJ12 JJ22 MM01                 5F072 PP10 YY15

Claims (4)

[Claims] 1. A dielectric layer is arranged on a metal thin film, an optical coupler made of a light transmitting medium is arranged on the opposite side, and a single or multiple layers are formed at the interface between the dielectric layer and the metal thin film by using an excitation light source. The surface plasmon is excited and propagated on the metal thin film, and the change of the dielectric layer changes the signal of the surface plasmon,
A method of signal processing by surface plasmon, which uses a signal of radiated light change due to the resonance of the changed surface plasmon and the optical coupler. 2. A structure in which a dielectric layer is arranged on a metal thin film and an optical coupler made of a light transmitting medium is arranged on the opposite side, and a single or a single layer is formed at the interface between the dielectric layer and the metal thin film by using an excitation light source. It is characterized in that multiple surface plasmons are excited and propagated on a metal thin film, and a signal change of the surface plasmon due to a change of a dielectric layer is obtained from a change of radiated light through an optical coupler having the above arrangement. Signal processing element by surface plasmon. 3. A thin film of a metal thin film in contact with the dielectric layer is thinned to about 1/50 to 1/50 of a light wavelength corresponding to the frequency of surface plasmons to be handled, and the dielectric film is sandwiched between the thin metal films. A light transmissive medium is placed on the opposite side of the layer, and the surface plasmon excited and propagated at the interface between the dielectric layer and the metal thin film is changed by the change of the dielectric layer, and the signal change of the surface plasmon can be obtained as a radiant light change. The optical coupler is configured so as to be possible.
A method of signal processing by the surface plasmon according to any one of 1 to 4 and a signal processing element. 4. The metal thin film is an aluminum layer, the dielectric layer thereon is a polyvinylcarbazole layer in which a cyanine dye is dispersed, and the light transmission medium on the opposite side is BK.
7 As a semi-cylindrical prism made of glass, the thickness of the aluminum thin film is set to about 10 to 1/50 of the excitation light wavelength, surface plasmons are excited and propagated at the interface between the metal thin film and the dielectric layer, and the dielectric layer of the dielectric layer is The method of signal processing by surface plasmon and the signal processing element according to claim 3, wherein the optical coupler is configured so that a change in radiated light can be obtained through the optical coupler by a change. .