JPS60208708A - Waveguide lens - Google Patents

Abstract

PURPOSE:To improve lens performance and to reduce manufacuring cost by constituting a waveguide lens of a polymerized accumulated monomolecular film so that sharp-edged microshapes are easily obtd. CONSTITUTION:The accumulated monomolecular film 10 (hereunder abbreviated as LB film) is formed on a substrate 2 by Langmuir-Projet method (hereunder abbreviated as LB method) using a photopolymerizable compd. having a hydrophobic part (e.g.; long chain alkyl group) and hydrophilic part (e.g., carboxyl group) within the same chemical strucrure. The LB film 10 is then patterned and exposed and thereafter the unexposed part is dissolved away by developing the film to build a lower part 11 of a waveguide consisting of the polymerized LB film. The polyermizable LB film 12 is formed by the LB method on the part 11 and the film 12 is exposed to a grating pattern. The unexposed part is dissolved away by developing the film and the intended waveguide lens is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens, and more particularly to a waveguide lens using an optical waveguide.

In recent years, with the development of optical cumulative circuits, there has been a demand for the development of highly accurate and efficient waveguide lenses.

First, the waveguide lens will be explained with reference to the drawings. 1 to 3 are schematic diagrams of waveguide lenses. Here, the first part (a) and (b) show an internal condensing grating lens, in which (a,) is a perspective view of a Fournel type grating lens, and (b) is a perspective view of a black diffraction type. FIGS. 2(a) and 2(b) show an external condensing grating lens, where (a) is a schematic plan view and (b) is a sectional view thereof.

In addition, FIGS. 3(a), (b), (c) and <% show mode index lenses.

In these figures, 2 is a substrate, for example glass, plastic or lithium niobate (LiNbO).
Transparent substrates such as, or opaque substrates such as silicon or ceramics are used. A guiding wavepath l is provided on the surface of the substrate 2. The optical waveguide l has a higher refractive index than the substrate 2. For example, when lithium niobate is used as a substrate, an optical waveguide l having a film thickness of about 0.5 to 5% can be obtained by thermally diffusing titanium (Ti) onto its surface.

Alternatively, if glass with a refractive index of 1.5 is used as a substrate, the surface of the glass with a refractive index of 1.55 (wavelength 8328
A) glass (for example, Corning Co., Ltd. product name C-705)
9) to a film thickness of 0.5 to 5 Ij by sputtering.

The optical waveguide 1 is obtained by forming a film to a certain extent. 3 is the grating (
(Fig. 1.2), and usually has a pitch of 0.3 to 1L and a depth of 0.1 to 0.2L. The guided light 4 propagates through the optical waveguide force of the waveguide lens configured in this manner by total reflection, is diffracted by the grating 3, and the emitted light 5 is converged or diverged.

In FIG. 3, reference numeral 6 denotes a mode index lens provided in a convex or concave optical waveguide l. In this case as well, the mode index lens 6 allows the guided light 4 to converge or diverge into emitted light 5.

However, in the past, in order to obtain a waveguide lens with desired precision, advanced microfabrication technology was required, which resulted in a drawback of lower yield and higher costs.

That is, generally the above grating 3 or mode,
Manufacturing index 6 was difficult. In order to improve the performance of the grating 3 or the mode index lens 6, it is desirable that the edge portion be a perfect rectangle, that is, a sharp etch is formed, but it is difficult to obtain such a perfect rectangle using conventional technology. It was extremely difficult.

The present invention has been made in view of the above, and an object of the present invention is to provide a waveguide lens that is easy to manufacture and inexpensive. A further object of the present invention is to provide a highly accurate and efficient waveguide lens.

That objective is overcome by using a monolayer, 1i (LB method).

Next, the single molecule accumulation method (LB method) will be explained. The monomolecular accumulation method is a method in which a monomolecular film formed on the water surface is transferred to the substrate surface and layered one by one to form an ultra-thin film.It is called the Langmuir-Blodgett method (LB method) named after the inventor.
Also called. Here, a monomolecular film refers to a uniform film with a thickness of one molecule, and a film obtained by accumulating this film is called a cumulative film. A monomolecular film and a cumulative film produced by this monomolecular accumulation method (LB method) are referred to as LB films.

The molecules constituting such a monomolecular film and a cumulative film must necessarily have at least a hydrophobic part and a woody part in the same chemical structure. The most typical hydrophobic moiety is a long-chain alkyl group, which generally has 5 carbon atoms.
A carbon number of 1 to 30 is used, but preferably a carbon number of 1
Ranked 0-25. Furthermore, both straight-chain alkyl groups and branched alkyl groups are useful, provided the length of the alkyl chain is appropriate. Examples of groups constituting other hydrophobic moieties include olefinic hydrocarbon groups such as eva, vinylene, vinylidene, and acetylene; condensed rapid phenyl groups such as phenyl, naphthyl, and anthranyl; There are polycyclic phenyl groups, etc., and these may be used alone or in combination, or may be located at the end or in the middle of the above-mentioned alkyl group. The most typical hydrophilic moieties include, for example, carboxyl groups and their metal salts and amine salts, sulfonic acid groups and their metal salts and amine salts, sulfonamide groups, amide groups, amino groups, imino groups, hydroxyl groups, Examples include a quaternary amino group, an oximino group, an oximino group, a diazonium group, a guanidine group, a hydrazine group, a phosphoric acid group, a silicate group, and an aluminate group. However, monomolecular films and cumulative films cannot always be formed with arbitrary combinations of hydrophobic parts and hydrophilic parts. As such, in the manufacturing process, first,
A monomolecular film must be formed on the water surface, but if the molecules are more hydrophilic than hydrophobic, they will dissolve in the water and become an aqueous solution, and conversely, if the hydrophobicity is superior, the molecules will form two phases. To separate. A monomolecular film is formed on the water surface when hydrophobicity and phyllophilicity are appropriately balanced. At this time, the molecules as a whole do not float or sink, but instead direct their hydrophilic parts toward the water phase and are adsorbed at the air-water interface, forming a monomolecular film. Therefore, the molecules constituting the monomolecular film and the cumulative film are required to have an appropriate balance of hydrophobic and hydrophilic parts.

Next, the LB film manufacturing apparatus and manufacturing method will be described with reference to FIGS. 4(A) and 4(CB).

The LB film manufacturing apparatus illustrated in FIGS. 4(A) and CB) was devised by Kuhn's research group based on the principles of the Langmuir-Prodgett method (LB method) described above. A frame 15 made of polypropylene is suspended horizontally inside a shallow and wide rectangular water 41114 to partition the water surface 23. The frame 15 functions as a two-dimensional cylinder as described below.

A polypropylene float 16 is floated inside the frame 15.

The width of the float 16 is made slightly narrower than the inside of the frame 15, so that it can move smoothly from side to side as a two-dimensional piston. A weight 17 is tied to the float 16 to pull it to the right. Generally, the repulsive force of a magnet is used to stop the float 1B or push it back to the left.

For this purpose, a magnet 19 fixed on the float 16 and a pair of magnets 20 that can be moved left and right are provided. That is, when pushing back, if the counter magnet 20 is brought close to the magnet 19, the attachment will work and the float 16 will be pushed back.

It is also possible to directly move the float 16 from side to side using a rotary motor or pulley instead of such a weight 17 or magnet 111.20. The left and right suction nozzles 22 are connected to a suction pump (not shown) via suction pipes 21, respectively. In the monomolecular accumulation method, clean pure water is used to prevent impurities from entering the monomolecular film and the cumulative film, but it is also necessary to clean the water surface 23 and quickly remove unnecessary monomolecular films. A suction pump and suction nozzle 22 (not shown) are utilized.

In that case, the water surface 23 is turned into sand by quickly sucking it out with the suction nozzle 12 while sweeping away the unnecessary monomolecular layer etc. with the float 16.

In this way, the float 16 was brought to the left end of the purified water surface 23, and several drops of a thin solution of the membrane constituent material dissolved in a volatile solvent such as benzene or chloroform were poured onto the water surface at a concentration of ~5 x 1O-3vaOe/t. After the solvent evaporates, a monomolecular film is left on the water surface 23. This monomolecular film exhibits two-dimensional behavior on the water surface 23.

When the areal density of molecules is low, it is called a gas film of a two-dimensional gas, and a two-dimensional ideal gas equation of state is established between the occupied area per molecule and the surface pressure. The occupied area and surface pressure are automatically and continuously measured by a measuring device (not shown). The occupied area and the amount of change thereof can be determined from the left and right movement of the float 1B. The surface pressure measuring device uses a method to measure the surface pressure indirectly from the difference in surface tension between pure water and the water surface covered with a monomolecular film, and a float 16 floating to separate the pure water surface and the monomolecular film surface. There are methods that directly measure the two-dimensional pressure applied to the surface, and each has its own characteristics. From the gas film state, the float 16 is gradually moved to the right to gradually reduce the extent of the water surface on which the monomolecular film develops and increase the surface density, which strengthens the intermolecular interactions and forms a two-dimensional liquid film. After that, it changes into a two-dimensional solid film. When the solid film is formed, the molecules are arranged and oriented neatly, resulting in the high degree of order and uniform ultra-thin film properties required for optical materials. Then, the monomolecular film is transferred to a clean substrate 24 while maintaining the state of the solid film.
(for example, substrates such as glass, ceramic, plastic or metal are used). Any number of additional layers of monolayers may be accumulated on top of the monolayer deposited on substrate 24. Generally, the surface pressure of a monolayer suitable for accumulation operation is 15 to 30 dyne/cm. Outside this range, the arrangement and orientation of molecules may be disturbed and the film may peel off, which is inappropriate.

However, in special cases, for example, depending on the chemical structure of the film-structuring material, temperature conditions, etc., a suitable surface pressure value may fall outside the above range, so the above range is only a rough guide.

A driving device (not shown) that drives the counter magnet 20 from side to side is controlled by a surface pressure control device (not shown) so that the monomolecular film can always maintain a constant surface pressure selected within the range of conditions suitable for cumulative operation. controlled.

For example, in the cumulative operation process, when a monomolecular film is transferred to the substrate 24, the surface pressure naturally decreases, so the magnet 20
, and therefore the float 16 to compress the area of the developed membrane and correct the decrease in surface pressure to maintain a constant surface pressure.

The monomolecular film 2B (see FIG. 5) is applied to the substrate 24 from above the water surface 23.
There are roughly two types of methods for transferring to the surface. - is the vertical immersion method, and the others are the horizontal attachment method. What is the vertical immersion method?Horizontal surface 2
A constant surface pressure suitable for the cumulative operation is applied to the monomolecular film 26 on the substrate 2 in a direction transverse to the film, that is, in a vertical direction.
In this method, the monomolecular film 26 is transferred by moving the monomolecular film 26 up and down. The horizontal deposition method is a method in which the substrate is held horizontally, placed as close to the water surface as possible from above, tilted slightly, and attached by touching the monomolecular film from one end. Each has its pros and cons. In the case of the vertical immersion method, three types of film structures can be formed as shown in FIGS. 3(A), (B), and (C) depending on the molecules constituting the film and the film fabrication conditions. Figure 3 (A) shows an X type in which the film adheres only during immersion; Figure 3 (B) shows a Y type in which the film adheres both during immersion and lifting; Figure 3 (C) shows a Y type in which the film adheres during pulling up. There is a Z-type, which only has a film attached to it.

Therefore, in the X type, the hydrophobic portion P is attached to the surface of the substrate 24, and the hydrophilic portion Q is attached to the outside. Z type is hydrophilic part Q
is attached to the surface of the substrate 24 with the hydrophobic portion P facing outward.

On the other hand, in the case of the horizontal deposition method, only an X-shaped cumulative film can be produced, but it is relatively easier to produce an X-shaped cumulative film with a superior cumulative ratio, which will be described later, than in the vertical dipping method. Furthermore, this horizontal deposition method is suitable for producing protein monolayers.

However, in either method, the substrate 24
The surface must be sufficiently clean interfacially. If the surface of the substrate 24 is insufficiently cleaned, the curtain will peel off, making it difficult to produce a cumulative film.

For example, if a glass substrate is immersed in a chromic acid mixture, washed with distilled water, and then dried in a clean air stream, its surface becomes completely hydrophilic.

For example, if you thoroughly apply molten iron stearate (m) to a cleaned solid surface and rub it thoroughly with a clean cloth such as gauze, then apply stearate with the mother wood group facing the solid surface. A monolayer of iron(m) acid is formed and the surface becomes completely hydrophobic.

In order to clarify the cumulative operation more specifically, Figure 6 (
In accordance with A), (B), and (C), the operation of producing a Y-shaped cumulative film by the vertical dipping method will be described. Illustrated example (6th
Figure) shows the case where a hydrophilic substrate 24 is used.

The first layer of the monomolecular film 26 that adheres to the hydrophilic substrate 24 is formed during the pulling process as shown in FIG. The order is to drop a dilute solution of the constituents. Then, the surface pressure is increased, and after reaching a surface pressure suitable for producing a cumulative film, the substrate 24 is lifted up. The pulling (lowering) speed suitable for cumulative film production is 0.1 to 10 cm/w.
It is in. However, suitable conditions may exist outside this range depending on the membrane constituent materials and membrane manufacturing conditions.

In the first lifting process, the first layer of heavy molecular membrane
is attached to the surface of the substrate 24, with the hydrophobic portion P facing outward.

In the next dipping (lowering) step (FIG. 4(B)), the second layer heavy molecular film is attached with the hydrophobic portion P facing the surface of the substrate 24 and the hydrophilic portion Q facing outward.

In addition, after applying the first layer 28a, it is better to dry it thoroughly in the air to remove moisture and other solvents, and then apply the second layer 26b or more, so that the cumulative film does not peel off and the cumulative operation is more successful. understood. For the third layer 28c and above, a cumulative film having an arbitrary number of layers can be produced by repeating the same operation. In the illustrated example, the odd-numbered layer of the Y-type film always has its woody part Q facing the surface of the substrate 24 and its hydrophobic part P facing outward. It has been confirmed through many experiments that it is equal to the product of the cumulative number of times (the number of monomolecular films) multiplied by the length (10 to 80 A). Other factors that affect the way the film adheres include (1) the chemical structure of the film constituents, (2) the pH of the aqueous phase and the type and concentration of salts it contains, (3) temperature, and (4) the type of substrate. There is. For example, it is easier to form a stable cumulative film with fatty acid salts than with pure straight-chain fatty acids, and salts such as calcium, barium, and cadmium are particularly good. In this case, the pH of the aqueous phase
The composition and deposition of the cumulative film differ depending on the type of material. That is, in general, if the pH is below, a pure fatty acid film will be obtained, if the pH is above 9, a metal salt film will be obtained, and if the pH is intermediate, a cumulative film containing these will be obtained. Note that an index called cumulative ratio is used to quantitatively display how the cumulative film is formed. The cumulative ratio refers to the ratio of the film area actually transferred from the water surface 23 to a predetermined area on the substrate. The area of the film transferred from the water surface is determined by measuring the amount of movement of the float 16. For example, a cumulative ratio of 0 indicates that no film has been deposited at all, and a cumulative ratio of 1 indicates that no film has been transferred. This shows the case where Generally, the cumulative ratio of metal salts is higher than that of free acids.

The substrate 24 used in the present invention may be any suitable substrate, and the substrate dimensions are not particularly limited.
The thickness of the B film is determined by repeating the above-mentioned accumulation (Ll
It ranges from ~5 ru.

A material suitable for the waveguide lens of the present invention has appropriate optical properties, has a higher refractive index than the substrate 2 (FIGS. 1 to 3), and is capable of forming an LB film. This is required. Particularly suitable are, for example, fatty acids, especially 10-3
This is a polymerizable LB film that is made of straight chain fatty acids (stearic acid, aragidic acid) containing 0 carbon atoms and their salts (cadmium salts), which will be described later.

The refractive index of these materials is easily controlled by appropriately selecting the length of the CR2 chain or by adding metal ions. The deposited LBlli is a well-known 4+,...
It is buttered by a means. Alternatively, it can be patterned into a desired shape using a novel patterning method related to another patent application (application number undetermined) by the present applicant.

The patterned LB film functions as a waveguide.

Next, a grating 3 or a mode or index lens 6 is obtained by digging fine grooves at desired locations on the surface of the LB film. Methods for forming gratings, modes, and index lenses include thermal deoxidation using laser, beam, or electron beam irradiation, and mechanical methods.

FIGS. 7(A), (B), and (C) show examples of manufacturing a waveguide lens according to the present invention.

The polymerizable LH film 1a is formed on the substrate 2 by the method described above so as to have a film thickness of 0.5 to 5 cm. Next, Figure 7 (A
), the hatched part of LBl19 is exposed to gamma rays at exposure 7,
Polymerizes by irradiating with electron beams or ultraviolet rays. The non-exposed portion 8 has a length of 1iILs or more, and a zero width which is not particularly limited and is in the range of 50A-10.0OOA.

FIG. 7 CB) shows the cross-sectional shape of the exposed part (8) and the unexposed part of the monomer LB film at 8.8 degrees. After exposure, it is dipped in benzene, chloroform, alcohol, etc.

The LB film 9 polymerized by the energy beam does not peel off and remains on the substrate, but the seven-layer LB film in the non-exposed portions 8 and 8' is dissolved and removed. However, since the non-exposed area 8 corresponding to the microstructure is extremely narrow, the penetration of the solvent is slower than the penetration into the wider non-exposed area, for example 8 degrees, and the same holds true for the elution rate of the monomer. In other words, a small area (for example 8 degrees) and a large area (for example 8 degrees) of the non-exposed part
), there is a speed difference between the erosion of the solvent and the elution of the solute, resulting in the formation of Figure 4(C).

Since LBlli is constructed by the accumulation of monolayers, its feature is that even when such elution is performed, it is eluted layer by layer. Furthermore, since the LB film also has a high degree of molecular orientation, the bottom surface of the fine structure can be extremely flat and have sharp edges.

Next, another manufacturing example of the present invention is shown in FIGS. 8(A) and CB).

This will be explained with reference to (C), (D), (E), and (F).

In each figure, 1. Polymerizable LBli 10 is deposited on the surface of the substrate 2 by the LB method (FIG. 8(A)).

2. Polymerizable LBIIIO is exposed (turning) to energy rays 7 such as light (FIG. 8(B)).

3. Next, it is developed (immersed in alcohol, chloroform, benzene, etc.) and the unexposed areas are dissolved and removed. 0 Polymerized LBrill is insoluble in the developer. In this way, a waveguide lower part made of polymerized LBrill is constructed (FIG. 8(C)).

4. A polymerizable LBli 12 is deposited on the lower part 11 of the waveguide by the LB method (FIG. 8(D)).

5. Next, the polymerizable LB film 12 is formed by an energy beam 7 such as light.
is exposed as a grating pattern (Figure 8 (E)).
.

8. Dissolve and remove the unexposed area by developing (Figure 8 (F)
), thus a grating type optical coupler is obtained.

Examples of the present invention are shown below.

<Example> ・Substrate glass, grating, pitch 200A grating depth 0.1 pot, 1#L 厘四凰M ・Olefin compound (photopolymerizable) ・Polymerization/non-polymerization by exposing vinyl stearate to γ rays Exposure section~
Soluble in alcohol - W-tricosenic acid polymerizes when exposed to electron beam (10 to 100 KeV) - Electron beam exposure device (JEOL JEBX-28) - Unexposed area - ethanol - Diacetylene derivative polymerizes with ultraviolet rays - Unexposed area -Chloroform, benzene.

dissolves in alcohol The unique effects of the present invention are as follows.

1. Due to the above-mentioned characteristics of the LB film, a microshape with sharp edges can be easily formed, so a waveguide lens with good lens performance can be obtained.

2. Since it is easy to manufacture, the manufacturing cost is low.

3. Since high temperature treatment is not required during the manufacturing process, non-heat resistant matte materials can be used.

[Brief explanation of the drawing]

Figure 1 (a), (b), Figure 2 (a), (b),
Figure 3(a). (b), (c> is a schematic diagram of the waveguide lens, Fig. 4 (A
), (B). FIG. 5(A) is a perspective view and a sectional view of the LB film manufacturing apparatus. (B) and (C) are diagrams explaining the three types of configurations of the LB film, Figures 6 (A), (B), and (C) are diagrams explaining the formation of the LB film, and Figures 7 and (A ), (B), (C) are detailed explanatory sectional views of the present invention, and FIGS. 8(A), (B), (
G), CD), (E), and (F) are explanatory sectional views of other manufacturing examples of the invention. 1... Optical waveguide 2... Substrate 3
...... Grating 4... Guided light 5 ... Outgoing light 6 ...... Mode Φ index lens 7 ・
・・・・・・ Exposure 8.8°・・・・・・ Non-exposed area (monomer LB film) 8
...... LB film (polymerized) 10... Polymerizable LB film 11 ...... Lower part of waveguide 12...
... Polymerizable LB membrane (a) (b) Whistle 1 diagram (C,) 411(a) 411(t)) (A) 11111111 (C) 9JA5 Figure 16 (A) Figure 7 (C) (F) Figure 28 Proceedings Amendment (Method) July 4, 1980 Commissioner of the Patent Office 1. Indication of the case 1988 Patent Application No. 84858 2. Invention Name of waveguide lens 3, Relationship to the person making the correction Patent applicant (100) Canon Co., Ltd. 4, Agent Address: 5-9-20, 1-9, Akasaka, Minato-ku, Tokyo Date of amendment order: Date of dispatch: On June 26, 1980, Figure 7 (B) was amended as shown in the attached sheet. (B) Figure 7

Claims (1)

[Claims] A waveguide lens comprising a monomolecular cumulative film.