KR100391979B1 - Variable beam splitter using a photorefractive material - Google Patents

Abstract

The present invention relates to a variable optical splitter using an optical refraction material. In particular, the variable optical splitter has a light refraction layer formed therein so that laser light for a target object generated from a light source can be controlled by a predetermined refractive index difference from an upper air layer. A variable light separation structure having a first transmission surface for splitting the first transmitted light and the first reflected light and a second transmission surface for splitting the first transmitted light into the second transmitted light and the second reflected light by a predetermined refractive index difference between the lower air layer And a blocking portion provided on a portion of the first transmission surface to prevent the second reflected light reflected from the second transmission surface from being reflected outside, and a variable light separation structure perpendicular to the first transmission surface and the second transmission surface. It is installed on both sides of the external power supply to the optical refraction material to change the amount of charge, and the refractive index of the variable optical separation sphere in accordance with the change of the charge amount By including the electrode unit for, unlike the variable light separator using a conventional number of devices consists of a single element. In addition, when the optical splitter is used to branch the laser light generated from the light source in an application system such as a volume holography digital storage system, the miniaturization of the system can be achieved by using the variable optical splitter composed of a single device of the present invention. You can get the effect.

Description

VARIABLE BEAM SPLITTER USING A PHOTOREFRACTIVE MATERIAL

The present invention relates to a variable optical separator using the optical refraction effect of the optical refraction material, and more particularly, an optical refraction material whose refractive index is changed according to the amount of charge of an external power source applied to the inside of the variable optical separation structure is charged from the light source. The present invention relates to a variable optical splitter using a light refraction effect for splitting laser light on a generated object into transmitted light and reflected light.

Recently, the field of technology using volume holographic digital data storage has been actively studied everywhere, for example, due to the remarkable development of semiconductor laser, charge coupled device (CCD), liquid crystal display (LCD), etc. As a result of these studies, fingerprint recognition systems for storing and reproducing fingerprints have been put to practical use, and are being expanded to various fields that can apply the advantages of large capacity and ultra-fast data transfer rate.

The volume holographic digital storage system as described above is a storage medium, for example, optical refraction, in which an interference fringe generated when the object light and the reference light from the target object are interfered with each other is sensitive to the amplitude of the interference fringe. By recording in a storage medium such as a crystal, recording the intensity and phase of the object light by a method of changing the angle of the reference light, etc., it is possible to display a three-dimensional image of the object and to display a page of binary data ( Hundreds to thousands of holograms can be stored in the same place.

On the other hand, in such a volume holographic digital data storage system, an optical splitter for dividing the laser light of the target object generated from the light source into two or more is essential.

1 is a block diagram of a variable optical separator used in a volume holographic digital data storage system according to the prior art.

As shown in FIG. 1, the variable light separator includes a light source 10, a first half-wave plate 20, a polarization separator 30, and a second half-wave plate 40.

The light source 10 generates the vertically polarized laser light required for holography, and the first half-wave plate 20 rotates the polarization direction of the vertically polarized laser light generated by the light source 10.

The polarization separator 30 separates the laser light whose polarization direction is rotated by θ by the first half wave plate 20 into light of horizontal polarization and light of vertical polarization, and the second half wave plate 40 is of the polarization separator 30. The light having polarization of the horizontal component separated by) is converted into the light of the vertical component.

The operation of the variable optical separator used for the holographic graphic configured as described above is as follows.

First, the laser light generated by the light source 10 is rotated in the polarization direction by the first half wave plate 20, and the laser light rotated by the angle θ by the first half wave plate 20 is transferred to the polarization separator 30. Thereby separating the light of the horizontal polarization and the light of the vertical polarization. In this case, the ratio of separation is that the vertical component has the intensity of sinθ of the laser light generated by the light source 10, and the horizontal component has the cosθ of the laser light generated by the light source 10.

The laser light having a horizontal component among the laser beams transmitted by the polarization separator 30 is converted into laser light having a vertical component by the second half wave plate 40.

As described above, the ratio of the intensity of the vertical and horizontal components separated by the polarization separator 30 may be adjusted by changing the angle of the laser light generated by the light source 10 using the first half wave plate 20.

However, when the variable optical splitter described above is used, many devices are required when implementing an application system such as a volume hologram storage system. In particular, the first halfwave plate 20 and the second halfwave plate 40 are essential for optical separation. It can be seen that required.

Therefore, the above-described variable optical separator acts as a major obstacle in miniaturizing the system, and development of a technology capable of simplifying such a variable optical separator has emerged as an urgent demand.

The present invention is a result of research efforts in accordance with the above-described requirements, the object is that the optical refractive material whose refractive index is changed in accordance with the amount of charge of the external power applied to the inside of the variable light separation structure is generated from the light source An object of the present invention is to provide a variable light splitter using a light refraction effect for splitting laser light on a target object into transmitted light and reflected light.

According to an exemplary embodiment of the present invention for achieving the above object, a laser beam for a target object generated from a light source is formed by forming a light refraction layer therein, and the first transmission light and the first transmission light A variable light separation structure having a first transmission surface for branching into reflected light and a second transmission surface for branching the first transmission light into second transmission light and second reflection light by a difference in refractive index between the lower air layer, and A blocking portion disposed on a portion of the first transmission surface to prevent the second reflected light reflected from the second transmission surface from being reflected outside, and a variable light separation structure perpendicular to the first transmission surface and the second transmission surface It is installed on both sides of the external power supply to the optical refraction material to change the charge amount, according to the change of the charge amount of the variable optical separation sphere An electrode part which changes a refractive index is included.

1 is a block diagram of a conventional variable optical splitter.

2 is a block diagram of a variable light separator according to the present invention.

3 is a view for explaining the operating principle of the variable optical splitter according to the present invention.

<Description of the code | symbol about the principal part of drawing>

10, 100: light source 20: first half-wave plate

30 polarization separator 40 second half-wave plate

200, 400: electrode 300: variable light separation structure

500: breaker

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a detailed block diagram of a variable light separator according to a preferred embodiment of the present invention.

As shown in FIG. 2, the variable light splitter includes a variable light splitting structure in which an optical refractive material whose refractive index changes in accordance with the amount of charge of the light source 100, the electrode parts 200 and 400, and the external power source is filled ( And the blocking part 500. The electrode parts 200 and 400 coat the both sides of the variable light separation structure 300 with a material forming a transparent electrode made of an oxide such as indium oxide. An external power source is applied to the light refraction material of the variable light separation structure 300. The variable light separation structure 300 is formed from the light source 100 by forming a light refraction layer filled with a predetermined light refraction material therein. The first transmission surface 310 which separates the laser light for the target object into the first transmitted light and the first reflected light by the predetermined refractive index difference with the upper air layer, and the first transmitted light by the lower air layer and the predetermined refractive index difference Second transmitted light and second half And a second transmitting surface (320) for splitting the light.

In addition, the variable light separation structure 300 is filled with an optical refractive material whose refractive index changes according to the amount of charge, such as lithium niobate, and whose reflectance changes due to the change of the refractive index, and the electrode portions 200 and 400. Reflectance and transmittance of the laser light with respect to the target object generated from the light source 100 are determined according to the amount of charge of the external power applied to the target.

The blocking unit 500 is installed on a portion of the first transmission surface 310 of the variable light separation structure 300, and prevents reflection of the first transmitted light transmitted through the variable light separation structure 300, such as aluminum or silicon. It is constructed by coating with a material to act as a mirror.

3 is shown as the same reference numerals for the same constituent members performing the same function as the plan view of FIG.

Hereinafter, the operating principle of the variable optical separator will be described.

Here, B1 is the first incident light incident from the light source 100, B2 is first reflected by the first transmission surface 310 by a predetermined refractive index difference at the interface with the upper air layer and then the variable light separation structure 300 The incident first transmitted light, B3 is the first reflected light reflected by the first transmission surface 310 due to a difference in refractive index at the interface between the variable light separation structure 300 and the air layer, B4 is the variable light separation structure 300 The remaining light after the first transmitted light is absorbed according to the predetermined refractive index according to the light refraction material of), and B5 is determined by a difference in refractive index between the second transmission surface 320 and the air layer of the variable light separation structure 300 among B4. The second reflected light reflected from the second transmissive surface 320, B6, is the second transmitted light finally passing through the medium after reflection occurring at the interface of the light refraction material and the air layer of the variable light separation structure 300.

When the incident light B1 generated by the light source 100 is incident on the first transmission surface 310 of the variable light separation structure 300 of the variable light separator, the incident light is indicative of the refractive index of air and the light refractive material of the variable light separation structure 300. The light is branched into the first reflected light B3 reflected by the first transmission surface 310 by the difference R, and the first transmitted light B2 incident on the first transmission surface 310 of the variable light separation structure 300.

In this case, the intensity of the first reflected light B3 and the first transmitted light B2 is determined according to the refractive index of the variable light separation structure 300 which changes according to the amount of charge of the external power applied to the electrode parts 200 and 400.

A part of the first transmitted light B2 incident on the variable light separation structure 300 is partially absorbed according to the absorption rate of the variable light separation structure 300, and after the absorption, the remaining B4 is the second transmission of the variable light separation structure 300. The second transmitted light B6 is emitted through the surface 320.

A part of B4 may be formed by a difference in refractive index between the lower air layer of the variable light separation structure 300 and the material of the variable light separation structure 300 before passing through the second transmission surface 320 of the variable light separation structure 300. The second transmission surface 320 is secondary reflected, the rest is transmitted through the second transmission surface 320. In other words, B4 is transmitted through the second reflected light B5 generated by the secondary reflection and the second transmission surface 320 of the variable light separation structure 300 to branch to the second transmitted light B6.

In this case, the second reflected light B5 that is secondly reflected is not emitted to the outside of the variable light separation structure 300 by the blocking unit 500 provided on a portion of the first transmission surface 310 of the variable light separation structure 300. The intensity of each light described above has the same relationship as in equation (1).

here, Is the intensity of the incident light B1 incident from the light source 100 first, Is the intensity of the first transmitted light B2, β is the light refraction material of the variable light separation structure 300 is determined according to the absorbance of the medium of the variable light separation structure 300, R is the amount of charge applied to the electrode portion (200, 400) Reflectance reflected by the difference between the refractive index and the refractive index of air, Is the intensity of light remaining after absorption in the variable light separation structure 300 according to the absorption rate of the medium, Is the intensity of the second transmitted light B6, which is secondly reflected by the second transmission surface 320 of the variable light separation structure 300 and finally transmitted through the medium, B is the traveling distance of the beam.

Intensity of second transmitted light transmitted through the variable light separation structure 300 Equation 1 is summarized as Equation 2 below.

The intensity of B3 which is the first reflected light reflected by the above-described primary reflection Called Is the same as Equation 3 below.

Intensity of light reflected by the primary reflection Intensity of light transmitted through the variable optical separation structure The ratio divided by is represented by Equation 4 below.

The reflectance R is represented by the following equation (5).

here, Is the refractive index of the first medium, Represents the refractive index of the second medium. Where the second medium is air Is 1

Substituting Equation 5 into Equation 4 expands,

Β in Equation 6 is an intrinsic value for each substance. Therefore, the intensity ratio of the two lights can be adjusted by adjusting the change of the refractive index or the moving distance of the beam.

First of all, in order to adjust the refractive index, it is possible to use a light refractive material.

The refractive index modulation amount when using a material having an optical refractive index is given by Pockel'Law (Equation 7).

Where Δn is the difference in refractive index Is the refractive index before modulation, Represents the electrooptic coefficiency, which represents the ratio of the refractive index that changes with the electric field and is an intrinsic constant for each material. E represents the electric field.

As shown in Equation 7 above And Since is an intrinsic constant value, the difference between the refractive index of the optical separator and the refractive index of air can be adjusted by adjusting the value of the electric field E.

Since the path of light, which is the second refractive index control method, cannot be changed after fabrication of the device, the thickness cannot be controlled and the angle of the incident beam must be controlled. In this case, the refractive index control method above is useful because the angle of the final beam must be corrected.

As described above, according to the present invention, the variable optical separator separates the light generated from the light source into two lights by using one device, unlike using many conventional devices, thereby requiring volume holographic separation of light. In an application system such as a digital data storage system, a variable optical splitter composed of a single device can be used to achieve the miniaturization of the system.

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

Claims (3)

A first transmission surface and a first transmission surface for forming a laser beam for the target object generated from the light source to the first transmitted light and the first reflected light by a difference in refractive index with the upper air layer formed therein, A variable light separation structure having a second transmission surface which branches into the second transmission light and the second reflection light by a predetermined refractive index difference from the lower air layer, A blocking part installed at a portion of the first transmission surface to prevent the second reflection light reflected from the second transmission surface from being reflected outside; Installed on both sides of the variable light separation structure perpendicular to the first transmission surface and the second transmission surface to apply an external power source to the optical refraction material to change the amount of charge, and according to the change of the amount of charge Variable light separator using a light refracting material comprising an electrode portion for changing the refractive index. The method of claim 1, wherein the electrode unit, A variable light separator using an optical refraction material, characterized in that the transparent light coating on both sides of the variable light separation structure with an oxide such as indium oxide (Indium Oxide). The method of claim 1, wherein the blocking unit And a mirror coating to prevent reflection of the second reflected light transmitted through the variable light separation structure.