JP2000187183A - Optical device for optical wiring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device for optical wiring giving a deflection function required for attaining compactness and without receiving strict limitations for manufacture. SOLUTION: The optical device 10 for optical wiring contains an optical substrate 11 transmitting light beams and a chip substrate 13 provided with a light emitting device 14 for an optical signal provided on the surface 11a of the optical substrate 11. In such a case, an image forming function and the deflection function of a computer generated hologram(CGH) element for guiding a beam from the light emitting device 14 into the optical substrate 11 are alotted to a first CGH element 16 provided on the chip substrate side and a second CGH element 17 provided on the optical substrate 11 answering to the first CGH element 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device for optical wiring suitable for use as a part of a so-called optoelectronic circuit, and particularly to a computer hologram (hereinafter, simply referred to as a CGH element). The present invention relates to an optical device suitable for a packaged optical device.

[0002]

2. Description of the Related Art In order to make an optoelectronic circuit compact, a package type optical device has been proposed. In this optical device, for example, an optoelectronic chip module on the light source side (hereinafter simply referred to as a light source side module) and an optoelectronic chip module on the light receiving side (hereinafter simply referred to as a light receiving side module) are optical substrates. The light from the light source side module provided on one surface is guided to the light receiving side module via a zigzag optical path in the optical substrate.

[0003] On both sides of an optical substrate on which both modules are provided, reflecting means for defining the zigzag optical path described above are provided in the optical substrate, and a light source side module is provided on the one surface of the optical substrate. And a condenser lens for guiding the light passing through the zigzag optical path to the light-receiving module, and both modules are optically coupled via the optical substrate. You.

The inventor of the present application has previously described Japanese Patent Application No. 9-24951.
In the specification of Japanese Patent Application Publication No. 2000-214, in this type of optical device, a zigzag optical path is adopted by adopting a deflecting means such as a diffractive optical element having a deflecting function instead of the reflecting means provided on the one surface of the optical substrate. It has been proposed that the bending angle can be set to a desired angle, thereby increasing the degree of freedom in designing a packaged optical device, or reducing optical loss due to reflection in a zigzag optical path. Also,
It has been proposed to use a CGH element as such a diffractive optical element.

As an application of such a CGH element, each of the condenser lenses provided on the one surface of the optical substrate corresponding to each of the light source side module and the light receiving side module is formed of a CGH element. Conceivable. When such a CGH element is used for the condenser lens, each CGH element can be provided with an imaging function and a deflection function, thereby increasing the degree of freedom in designing the optical device.

As will be described later, a CGH element is formed by etching a lens material using a mask pattern obtained by computer processing an optical path difference coefficient of a Taylor expansion approximation formula derived from an optical path difference function showing desired optical characteristics. It is formed by processing.

[0007] The minimum line width of the mask pattern is directly affected by the performance of the CGH element. That is, if a deflection function in addition to an imaging function is to be imparted to the CGH element in a multiplex manner, the combination of these two functions will minimize the minimum line width of the mask pattern. May be smaller as the value exceeds. In order to avoid this, the deflection angle is sacrificed and a sufficiently large deflection angle cannot be given to the CGH element.
Regarding the deflection function given to the element, the deflection angle is strongly restricted in manufacturing.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical device for optical wiring which can provide a deflection function necessary for downsizing and is not subject to strong manufacturing restrictions. It is in.

[0009]

Means for Solving the Problems <Structure> The present invention is basically provided with an optical substrate allowing light transmission, and a light emitting device or a light receiving device for an optical signal, and is provided on a surface of the optical substrate. In the optical device for optical wiring including a chip substrate provided, a CHG element for guiding light from the light emitting device into the optical substrate or each of a CHG element for guiding light from within the optical substrate to the light receiving device. A first CGH provided on the chip substrate side has an image forming function and a deflecting function of the CGH element.
The element and a second CGH element provided on the optical substrate corresponding to the first CGH element are shared.

<Operation> In the optical device for optical wiring according to the present invention, the first CGH element provided on the surface of the chip substrate facing the optical substrate is provided with, for example, a collimating function and provided on the optical substrate. For example, a light collecting function and a deflecting function can be given to the second CGH element to be obtained.
Alternatively, for example, an imaging function can be given to the first CGH element, and a deflection function can be given to the second CGH element.

In any case, it is possible to eliminate the combination of the image forming function and the deflecting function that gives the smallest line width to the mask pattern for the CGH element obtained by the computer processing. Therefore, the limitation on the minimum line width dimension of the mask pattern for forming each CGH element is relaxed.
It is possible to provide the H element with a deflection function sufficient for downsizing, and to provide an optical device for optical wiring that is not subject to strong restrictions in manufacturing.

Prior to the description of the embodiments of the present invention, a procedure for manufacturing a CGH device according to the present invention will be outlined. C
CAD is used for manufacturing the GH element, and a phase difference function of light in the CGH element exhibiting desired diffractive optical characteristics is obtained. This phase difference function is represented by an optical path difference function ρ (x,
y). The optical path difference function [rho (x, y) is transformed equation [rho (x, y) = a ΣC _N x ^m y ⁿ ... polynomial represented by (1). This polynomial (C _N x ^m y
coefficient C _N of ⁿ⁾ is called an optical path difference coefficient. n and m are positive integers, respectively, and the coefficient C _N is also called a phase coefficient. The following equation holds between N and m, n: N = {(m + n) ² + m + 3n} / 2 (2)

The optical path difference coefficient C _N is obtained as each term coefficient of the Taylor expansion approximation equation obtained by the two-dimensional Taylor expansion, and is substituted into a CAD program, so that a photolithography necessary for obtaining a desired shape by photolithography is obtained. A mask pattern can be generated. One example of such a CAD program is NIPT's CghCAD in California, USA.
There is.

In the CAD program, the condition that the sum of m and n is equal to or less than 10 and N is equal to or less than 65 is given from the relation of data processing capacity. Therefore, an optical path difference function ρ (x, y) showing desired optical characteristics is obtained, and each optical path difference coefficient C _N (C _0-
After obtaining C ₆₅ ), by inputting the data to a CAD program, a mask pattern for a CGH element exhibiting desired diffractive optical characteristics can be obtained.

Each of the phase coefficients C _{0 to} C ₆₅ is obtained from a two-dimensional Taylor expansion of the two-dimensional optical path difference function ρ (x, y) with respect to the x-axis and the y-axis, and from an approximate expression up to the tenth-order term. Can be. This relationship is represented by equation (3) shown in FIG. Δ in the second term on the right side of Expression (3) is a surplus term in the Taylor expansion, and is a value small enough to be ignored.

An optical path difference function ρ (x,
y), the phase coefficients C _{0 to} C ₆₅ are obtained from the arithmetic processing of the optical path difference function ρ (x, y) by the equation (3), and these values are input to the CAD program described above to obtain the desired values. Mask conditions for a computer generated hologram exhibiting the above diffractive optical characteristics can be obtained. A required number of masks are manufactured in accordance with the mask pattern, and a lens material is etched by photolithography using a combination of these masks, whereby a CGH element exhibiting desired diffractive optical characteristics is obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a sectional view schematically showing an optical device according to the present invention. The optical device 10 according to the present invention includes a flat optical substrate 11 having a pair of parallel flat surfaces 11a and 11b. The optical substrate 11 is made of, for example, an optical glass material having a refractive index n of 1.5.
For 1, a material exhibiting high translucency with respect to the wavelength of light to be handled, for example, a silicon substrate or the like can be used.

On one flat surface 11a, that is, the front surface 11a of the optical substrate 11, a first chip module 12, which is located on the light source side, for example, is provided. Chip module 12
Is a light emitting device 14 comprising a flat semiconductor chip substrate 13 having a pair of parallel planes 13a and 13b, and a surface emitting laser emitting light having a wavelength of, for example, 1.55 μm provided on the semiconductor chip substrate. And

The semiconductor chip substrate 13 has one surface 1
The optical substrate 1 is connected via the solder bumps 15 provided on the optical substrate 1a.
It is fixed to the surface 11a of the optical substrate so that the distance W from the substrate 1 is, for example, 50 μm. Also, the light emitting device 14
Means that the light from the light emitting surface 14a is
The light-emitting surface 14a is placed on the semiconductor chip substrate 13 so that the light-emitting surface
Is fixed to the other surface 13b of the chip substrate 13 toward the surface 13a. In the example shown in the figure, for example, a silicon substrate having a refractive index n of 3.5 is used as the chip substrate 13.

A first surface 13a of the chip substrate 13 has a first surface for guiding the spherical divergent light from the light emitter 14 as a parallel light beam toward the surface 11a of the optical substrate 11.
Is provided so as to be located immediately below the light emitting surface 14a. A second CGH element 1 for guiding light from the first CGH element 16 to a predetermined position in the optical substrate 11 is provided on the front surface 11a of the optical substrate 11.
7 is provided immediately below the first CGH element 16.

In the illustrated example, the light emitting surface 14a of the light emitting device 14
Is converted into a parallel light flux by the first CGH element 16, and the parallel light flux is converted into a depth in the z-axis direction in the optical substrate 11 by the second CGH element 17. The light is focused on a position indicated by a position of 5 mm and a displacement position of 1 mm in the x-axis direction.

Therefore, the first CGH element 16 and the second
Both of the CGH elements 17 have a collimating function of defining an optical path to a converging point on one side and defining a parallel light path on the other side. Also, the first CGH element 16 is
Although it shows a coaxial collimating function, the second CGH element 1
Reference numeral 7 denotes an off-axis type collimating function because a deflection function is added.

FIG. 2 shows a CGH element having a collimating function.
It is explanatory drawing which shows the optical characteristic of a child (16 and 17).
For simplicity of explanation, CGH elements (16 and 17)
Is on the z-axis and its thickness dimension is negligibly
Use small values for minutes. This assumption is based on the phase coefficient C _NCalculation of
Above, does not detract from the generality. CGH element (1
6 and 17) are the focal points as shown in FIG.
The spherical divergent light from (X, Y, Z) is vector
Is converted into a parallel light flux parallel to the light components (α, β, γ).

Optical path difference of CGH elements (16 and 17)
The number ρ (x, y) is given by the following equation: ρ (x, y) = n₁・ ｛(X−x)^Two+ (Y−y)^Two+ Z^Two｝^1/2-N₁・ Ln_Two・ (Αx + βy) (α^Two+ β ^Two + γ^Two)^{− (1/2)} .. (4).

Here, n ₁ is the refractive index of the medium on the converging point side, and n ₂ is the refractive index of the medium on the opposite side, that is, on the parallel light beam side. L is the distance from the focal point to the origin, and is represented by the following equation: L = (X ² + Y ² + Z ² ) ^1/2 (5)

Therefore, by substituting equation (4) into equation (3) and performing the operation, the phase coefficient C
_{0 to} C ₆₅ can be obtained, and these values are calculated by
By inputting to the AD program, mask conditions for a computer generated hologram (CGH element) can be obtained. A required number of masks are manufactured along the mask pattern, and the CGH elements (16 and 17) are etched by etching the lens material (13 and 11) using a photolithography method based on a combination of these masks.
Is obtained.

In the above-described optical element manufacturing process, the number of photomasks obtained by executing the CAD program is determined by the number of masks which is one of the parameters input when the program is executed. . Assuming that the number of masks is M, the lens step formed by etching, that is, the phase level N is 2
^Since it is represented by ^M , the greater the phase level N, the more
That is, as the number M of masks increases, a lens shape closer to the ideal Fresnel lens shape is obtained.

However, as the number M of masks increases, the width dimension of the mask pattern decreases. Therefore, if the minimum line width dimension of the mask pattern in the combined mask becomes smaller than the error tolerance based on the resolution in photolithography, the C
Manufacture of a GH element is practically impossible. for that reason,
When a mask is obtained as mask data by performing CAD, it is necessary to determine whether or not the mask can be applied to photolithography based on the minimum line width dimension of the mask pattern and an allowable error in photolithography. There is.

Optical path difference function ρ (x, y) indicating lens characteristics
Includes a single projecting area portion, the minimum line width dimension of the mask pattern for the lens showing the optical path difference function, that is, the mask width dimension P on the boundary line of the lens area, is derived from the approximate expression of the Fresnel lens. P = λ / ｛N · | grad ρ (x, y) |｝ (6) Here, λ is the wavelength of light from the exposure source used for photolithography, and N is the number of phase levels for one wavelength λ.

Therefore, the optical path difference function ρ shown in equation (1)
It is determined whether or not a single protrusion region exists in the lens region of (x, y). For this determination, the function y = f
The determination method of the maximum value and the minimum value of (x) can be applied, and x and y of the optical path difference function ρ (x, y), respectively.
Is obtained, and if the value of each partial derivative is non-zero, positive or negative, it can be determined that a single salient region exists in the lens region.

The optical path difference function ρ (x, y) shown in equation (5)
Each of the second-order partial differential equations for x and y with respect to indicates a positive value. Therefore, the optical path difference function represented by the equation (5) has a single protruding region in the lens region. From this, the minimum line width dimension P of the mask pattern for the CGH elements (16 and 17) showing the optical path difference function of the equation (5) can be obtained from the equation (6).

FIG. 3 shows the minimum line width of the mask for obtaining each of the CGH elements 16 and 17 obtained by the equation (6).
The minimum line width dimension of the mask for those calculation results,
6 is a graph showing the relationship with the position in the x-axis direction as a vertical axis and a horizontal axis. In the above graph, each CGH element (16 and 17) was calculated assuming two phase levels (M = 1). Further, a value of 1.55 μm was adopted as the wavelength λ.

The characteristic line 18 of the graph is the first axis of the coaxial type.
3 shows the mask width characteristic of the CGH element 16 and shows line symmetry with respect to the y-axis. On the other hand, a characteristic line 19 indicates a mask width characteristic of the second CGH element 17 of an off-axis type having a deflection function, which is asymmetric with respect to the y-axis.

As is clear from the characteristic line 19, 200 μm
When the second CGH element 17 having a diameter of m is obtained, the minimum line width of the mask used for the etching process of the lens material is a value exceeding 2 μm. Also, as is apparent from the characteristic line 18, the first CGH having a diameter of 200 μm
When the element 16 is obtained, the minimum line width of the mask used for etching the lens material slightly exceeds 1 μm.

In any case, two CGH elements (16
In order to obtain the optical characteristics shown in FIG. 1 by the combination of (1) and (2), the minimum mask width dimension for obtaining each CGH element (16 and 17) having a diameter of 200 μm exceeds 1 μm.

<Comparative Example> On the other hand, as shown in the comparative example of FIG. 4, a single CGH element 20 formed on the front surface 11a of the optical substrate 11 is used for the CGH element (1) shown in FIG.
In order to obtain the same optical characteristics as the combination of 6 and 17), a single CGH element 20 has an imaging function and a deflection function each having a condensing point (one of which is usually referred to as a light source point). It is necessary to add functions.

FIG. 5 shows the optical characteristics of the CGH element 20 having such an image forming function and a deflecting function.
The CGH element 20 shown in FIG. 5 includes a divergent point light source (X1, Y
1, Z1) at the focal point (X2, Y2, Z2). Refractive index of the point light source side of the medium is indicated by n _1, the refractive index of the focal point side of the medium is indicated by n _2.

The optical path difference function ρ (x, y) of the CGH element 20
Is given by ρ (x, y) = n₁・ ｛(X₁−x)^Two+ (Y₁−y)^Two+ Z^Two｝^1/2-N₁・ L₁+ N_Two・ ｛(X_Two−x)^Two+ (Y _Two −y)^Two+ Z^Two｝^1/2-N_Two・ L_Two .. (7).

Here, L ₁ is the distance from the point light source to the origin, and L ₂ is the distance from the condensing point to the origin. The following equation is obtained: L ₁ = (X ₁ ² + Y ₁ ² + Z ₁₎ ^{2) 1/2 ... (8) L} 2 = (X 2 2 + Y 2 2 + Z 2 2) obtained by the ^1/2 (9).

FIG. 6 shows the relationship between the minimum line width of the mask and the position in the x-axis direction based on the calculation results of the minimum line width of the mask for obtaining the CGH element 20. It is a graph shown as a vertical axis and a horizontal axis. In the graph, as in the first embodiment, the calculation was performed assuming that the CGH element 20 has two phase levels (M = 1).

The characteristic line 21 of the graph shows the mask width characteristic of the off-axis type CGH element 20 having the image forming function and the deflecting function.
Asymmetric about the axis. As is apparent from the characteristic line 21, when the CGH element 20 having a diameter of 200 μm is obtained, the minimum line width of the mask used for etching the lens material is about 0.6 μm, which is far below 1 μm.

As is clear from the comparison between the specific example 1 and the comparative example, the specific example 1 according to the present invention has a minimum mask line width required to obtain the same optical characteristics as the comparative example. Is approximately doubled.

According to the first embodiment, the minimum line width of the mask becomes larger when the same optical characteristics are obtained as compared with the comparative example. It means that it can be manufactured. Also,
If the mask has the same minimum line width, it means that the deflection angle can be set larger, which means that the degree of freedom in design is increased.

<Embodiment 2> Optical device 10 shown in FIG.
In FIG. 7, the same components as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, except for the CGH elements 22 and 23.

In the example of the optical device 10 shown in FIG. 7, the spherical divergent light diverged on the y-axis from the light emitting surface 14 a of the light emitter 14 on the chip substrate 13 is imaged by the first CGH element 22. An image is formed at a converging point which is a point, and the convergent light toward this image point is moved by the second CGH element 23 to a depth position of 5 mm in the z-axis direction in the optical substrate 11 and a displacement position in the x-axis direction Are deflected to the location indicated by 1 mm.

Therefore, the first CGH element 22 has the same imaging function as the CGH element 20 in the comparative example,
It is a coaxial type and has no deflection function. Also, the second CG
The H element 23 has a prism function of converting a parallel light beam into a parallel light beam at a predetermined deflection angle.

With respect to the first CGH element 22, since it is considered that both the point light source and the condensing point are located on the Z axis in the same optical characteristics as shown in FIG. 5, the optical path difference function ρ (x, y) is basically represented by the above equation (7).

On the other hand, the second CGH element 23 is considered to be a prism, that is, a linear grating, and its optical characteristics are shown in FIG. The second CGH element 23 having a prism function deflects a parallel light beam having an arbitrary deflection angle into a parallel light beam having an arbitrary deflection angle. For the sake of simplicity, it is assumed that the second CGH element 23 is in a plane passing through the origin and including the X axis and the Y axis, as described above. The parallel light flux incident on the CGH element 23 is
The parallel light flux which is parallel to the vector component (α ₁ , β ₁ , γ ₁ ) of the light passing through the origin and the vector component (α
₂ , β ₂ , γ ₂ ). Incident light-side medium of the incident parallel light beam is present, has a refractive index n _1, emission light-side medium where outgoing parallel beam is present has a refractive index n _2.

The optical path difference function ρ of the second CGH element 23
(X, y) is given by the following equation: ρ (x, y) = n₁・ (Α₁・ X + β₁・ Y) ・ (α₁ ^Two+ β₁ ^Two+ γ₁ ^Two)^{− (1/2)}-N_Two・ (Α_Two・ X + β _Two ・ Y) ・ (α_Two ^Two+ β_Two ^Two+ γ_Two ^Two)^{− (1/2)} .. (10)

The first C having the coaxial imaging function
GH element 22 and second CGH having prism function
Each of the second-order partial differential expressions for x and y for the optical path difference function ρ (x, y) shown in Expressions (7) and (10) for the element 23 indicates a positive value. Therefore, both the optical path difference functions expressed by the equations (7) and (10) have a single protrusion area in the lens area. From this, the minimum line width dimension P of the mask pattern for both CGH elements (22 and 23) can be obtained from Equation (6).

The first C having the coaxial imaging function
GH element 22 and second CGH having prism function
With respect to the element 23, the same calculation result of the minimum mask width as described above was obtained using the equations (7) and (10). The calculation result is shown in FIG. 9 as a graph showing the relationship between the minimum mask width and the position in the x-axis direction. In the graph of FIG. 9, as in the graph of FIG. 8, each CGH element (22 and 23) was calculated assuming two phase levels (M = 1). Further, a value of 1.55 μm was adopted as the wavelength λ.

The characteristic line 24 of the graph is the first axis of the coaxial type.
3 shows the mask width characteristic of the CGH element 22 and shows line symmetry with respect to the y-axis. On the other hand, a characteristic line 25 indicates the mask width characteristic of the second CGH element 23 having the prism function, and is asymmetric with respect to the y-axis.

As is apparent from the characteristic line 25, 200 μm
When obtaining the second CGH element 23 having a diameter of m, the minimum line width of the mask used for etching the lens material exceeds 2 μm. Also, as is clear from the characteristic line 24, the first CGH having a diameter of 200 μm
When the element 22 is obtained, the minimum line width of the mask used for etching the lens material slightly exceeds 1 μm.

In any case, as in the first embodiment, in order to obtain the optical characteristics shown in FIG. 1 by combining two CGH elements (22 and 23),
The minimum mask width dimension for obtaining each CGH element (22 and 23) having a diameter of 200 μm is a value exceeding 1 μm.

Therefore, according to the specific example 2, since the minimum line width of the mask becomes larger when obtaining the same optical characteristics as compared with the comparative example, it can be more easily manufactured from the relationship with the resolution of photolithography. . Further, if the mask has the same minimum line width, the deflection angle can be set to be larger, thereby increasing the degree of freedom in design.

Further, in the first specific example, it was necessary to make the optical axes of both CGH elements (16 and 17) coincide with each other, but in the second specific example, the second CGH element 23 was a linear grating. Therefore, the second CGH element 23 simply functions as a deflection grating. Therefore, in the second specific example, regarding the arrangement of the second CGH element 23,
It is not necessary to match the optical axis of the GH element 22 and both CGs
Since the arrangement condition of the H element is relaxed as compared with that of the first specific example, the manufacture is further facilitated.

FIG. 10 shows an application example of the optical device 10 according to the present invention. The light emitting chip module 12 and the light receiving chip module 1
2 'are laterally spaced from one another.

As described above, the chip module 12 includes a chip substrate 13 on which a light emitting device 14 is provided.
1a.

The light from the light-emitting surface 14a of the light-emitting device 14 is supplied to the semiconductor chip substrate 1 as described in the first specific example.
3, the second CG provided on the surface 11a of the optical substrate 11 by the collimating function of the first CGH element 16 provided on the one surface 13a facing the optical substrate 11.
The second CGH element is guided by the H element 17 and guided into the optical substrate 11 at a deflection angle θ by the collimating function.

On the other hand, the chip module 12 ′ has a chip substrate 13 fixed on the front surface 11 a at a distance W from the optical substrate 11 via the bump 15, similarly to the chip module 12, and the front surface 11 a of the chip substrate. The light receiving device 1 such as a photodiode provided on one surface 13a opposite to the
4 '. The light receiver 14 'is arranged with its light receiving surface 14a' facing one surface 13a.

On the one surface 13a of the chip substrate 13, a first CGH similar to the one described above having a collimating function for guiding an optical signal to the light receiving surface 14a 'of the light receiver 14' via the chip substrate 13 is provided. An element 16 is formed. In addition, immediately below the first CGH element 16 of the chip module 12 ′, the signal light from the optical substrate 11 is
A second CGH element 17 having a collimating function for guiding to the GH element 16 as described above is formed.

A reflection type imaging lens 2 for defining a zigzag optical path in the optical substrate 11 is provided between the two chip modules 12 and 12 ′ on the surface 11 a of the optical substrate 11.
7 are arranged. Also, the back surface 11b of the optical substrate 11
Is formed with a reflective film.

The signal light guided at a deflection angle θ from the second CGH element 17 of the light emitting side chip module 12 into the optical substrate 11 by the reflection action of the reflection film (11b) and the lens 27 is applied to the zigzag. The light is guided to the second CGH element 17 of the light receiving side chip module 12 ′ via the optical path, and further guided to the light receiver 14 ′ via the first CGH element 16.

The zigzag optical path is formed in a line-symmetric pattern with the center line C as an axis. By setting the deflection angle θ to be large, the thickness of the optical substrate 11 does not increase. , The aforementioned lateral spacing between the two chip modules 12 and 12 ′ can be reduced, whereby the two chip modules 12 and 12 ′ can be reduced.
It is possible to reduce the size of the optical device 10 including Therefore, as described above, the present invention, in which the restriction on manufacturing can be relaxed and the deflection angle θ can be increased, is extremely effective for making the optical device 10 compact.

[0065]

As described above, in the optical device according to the present invention, it is not necessary to combine the imaging function and the deflection function in one CGH element, and both functions can be shared by two CGH elements. The limitation on the minimum line width dimension of the mask pattern for forming each CGH element is relaxed, so that the CGH element can be given a sufficient deflection function for achieving compactness and is subject to strong manufacturing restrictions. Never. Therefore, according to the present invention, the deflection angle can be set relatively large without being subjected to strong manufacturing restrictions, and thereby the degree of freedom in design can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing Example 1 of an optical device according to the present invention.

FIG. 2 is an explanatory diagram illustrating optical characteristics of a CGH element of Example 1.

FIG. 3 is a graph showing a minimum line width dimension of a mask according to a specific example 1;

FIG. 4 is a drawing similar to FIG. 1 showing a comparative example.

FIG. 5 is an explanatory diagram showing optical characteristics of a CGH element of a comparative example.

FIG. 6 is a graph showing a mask minimum line width dimension of a comparative example.

FIG. 7 is a cross-sectional view schematically showing an optical device of a specific example 2.

FIG. 8 is an explanatory diagram showing optical characteristics of the CGH element of Example 2.

FIG. 9 is a graph showing a minimum line width dimension of a mask according to the second embodiment.

FIG. 10 is a cross-sectional view of an optical device showing an application example of the present invention.

FIG. 11 is an explanatory diagram of a Taylor expansion formula.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 optical device 11 optical substrate 12, 12 ′ chip module 13 chip substrate 14 light emitting device 14 ′ light receiving device 16, 22 first CGH element 17, 23 second CGH element

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 AA26 AA59 AA62 AA65 CA01 CA05 CA08 CA09 CA17 CA18 CA23 2K008 AA00 CC03 DD12 FF11 FF12 FF13 FF14 FF27 HH01 HH25

Claims (4)

[Claims] 1. An optical substrate that allows light to pass therethrough, and a chip substrate disposed on a surface of the optical substrate, the other being opposite to one surface of the chip substrate facing the surface of the optical substrate. A chip substrate having a light emitting device for an optical signal arranged with a light emitting surface facing the one surface of the chip substrate, and formed on the one surface of the chip substrate,
A first CGH element having a light condensing function for guiding light from the light emitter to the surface of the optical substrate;
A second CGH formed on the surface of the optical substrate facing the H element and having a deflecting function to angularly guide the light from the light emitter passing through the first CGH element into the optical substrate; An optical device for optical wiring, comprising: an element; 2. An optical substrate that allows light to pass therethrough, and a chip substrate disposed on a surface of the optical substrate, the other being opposite to one surface of the chip substrate facing the surface of the optical substrate. A chip substrate having a light receiver arranged with a light receiving surface facing the one surface of the chip substrate, and an optical signal formed on the one surface of the chip substrate, the optical signal being transmitted to the light receiver. A first CGH element having a light-condensing function for guiding, and a light formed on the surface of the optical substrate facing the first CGH element and guided at an angle in the optical substrate by the first CGH element. A second CGH element having a deflecting function for guiding to one CGH element. 3. The optical device according to claim 1, wherein the first CGH element has a collimating function, and the second CGH element has a condensing function and a deflecting function. apparatus. 4. The optical device according to claim 1, wherein the first CGH element has an image forming function, and the second CGH element has a deflecting function.