JPH11125718A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the package type optical device which is increased in the degree of design and can reduce optical loss due to reflection on a zigzag path and makes the manufacture relatively easy. SOLUTION: This device includes an optical substrate 11, a chip substrate 12 which has a light source 13 and a photodetector 14 and is arranged on one surface 11a of the optical substrate 11, a 1st lens 16 for light convergence which guides the light from the light source 13 into the optical substrate 11, a reflecting means 21 which reflects the light guided into the optical substrate 11 on one surface 11a of the optical substrate 11, deflecting means 18 and 19 which cooperate with the reflecting means 21 to prescribe a zigzag path 22 passing through the optical substrate 11, and a 2nd lens 17 for light convergence which guides the light passed through the zigzag path 22 to the photodetector 14. The 1st lens 16 and 2nd lens 17 and deflecting means 18 and 19 are provided on the chip substrate 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device suitable for use as a part of a so-called optoelectronic circuit, and more particularly to a package type optical device using a computer generated hologram (hereinafter simply referred to as a CGH element). An optical device suitable for the 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 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 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 second condenser lens for guiding the light passing through the zigzag path to the light receiving side module. Both modules are provided via the optical substrate. Optically coupled.

The inventor of the present application first employs a deflecting means such as a diffractive optical element having a deflecting function in this type of optical device, instead of the reflecting means provided on the one surface of the optical substrate. This makes it possible to set the bending angle of the zigzag path to a desired angle, thereby increasing the degree of freedom in designing the packaged optical device or reducing the optical loss due to reflection on the zigzag path. Proposed.

[0005]

However, in addition to the first and second condenser lenses, a deflecting means such as a diffractive optical element is formed on the one surface of the optical substrate with high precision. Therefore, the manufacturing process of the optical device becomes complicated as the manufacturing process of the optical substrate becomes complicated.

Accordingly, an object of the present invention is to increase the degree of freedom in designing a packaged optical device or to reduce optical loss due to reflection on a zigzag path, and furthermore, to relatively manufacture a device. It is to provide an easy optical device.

<Structure> The present invention comprises an optical substrate that allows light to pass therethrough, a light source for an optical signal, and a light receiver for receiving an optical signal spaced from the light source. A chip substrate arranged on one surface of the first substrate, a first condenser lens for guiding light from the light source into the optical substrate,
Reflecting means provided on the optical substrate for reflecting light guided into the optical substrate toward one surface of the optical substrate,
An optical device comprising: a deflecting means for defining a zigzag path through the optical substrate in cooperation with the reflection means; and a second condensing lens for guiding the light having passed through the zigzag path to a light receiver. The first and second condenser lenses and the deflecting means are provided on a chip substrate.

<Operation> In the optical device according to the present invention, the first
The second condensing lens and the deflecting means are formed on a chip substrate such as a semiconductor substrate. Therefore, it is not necessary to incorporate complicated optical elements such as a condenser lens and a deflecting unit into the optical substrate. In addition, since the chip substrate on which the first and second condensing lenses and the deflecting unit are incorporated is applied with a fine processing technology such as an integrated circuit technology for incorporating an optoelectronic circuit therein, The condensing lens and the deflecting unit can be relatively easily and highly accurately incorporated into the chip substrate.

Therefore, according to the present invention, a first condenser lens for guiding the light to the optical substrate, a second condenser lens for guiding the guided light to the light receiver, and a second condenser lens between the two condenser lenses. The deflection means for defining the zigzag path is incorporated in the chip substrate, and the deflection angle of the zigzag path can be set to a desired value by the deflection means. In addition to being able to reduce optical loss due to reflection of light, it is possible to provide an optical device that is relatively easy to manufacture.

Each of the first and second condensing lenses and the deflecting means can be constituted by a CGH element.
As will be described later, a CGH element is formed by introducing a computer into its manufacturing process and using photolithography and etching techniques used in a semiconductor manufacturing process. Therefore, by configuring the first and second condensing lenses and the deflecting means with CGH elements, these can be formed relatively easily and with high precision.

The deflecting means can be constituted by a pair of CGH elements each having a deflecting function and mutually forming a confocal relay lens system. This relay lens system enables the coupling distance between the two condenser lenses to be increased without inducing the effect of divergence due to light diffraction.
Further enhance design flexibility.

[0012]

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 is made of, for example, an optical glass material and has a pair of flat surfaces 1 parallel to each other.
1a and 11b, a flat optical substrate 11 and one flat surface 12a opposing one flat surface 11a of the optical substrate.
a and a chip substrate 12 including the other flat surface 12b on the opposite side.

The chip substrate 12 is made of a semiconductor substrate such as a silicon substrate. On the other surface 12b of the chip substrate 12, a light source 13 and a light receiver 14 for an optical signal are provided.
Are arranged so that the light emitting surface and the light receiving surface, which are the respective functional surfaces, face one surface 12a of the chip substrate 12 and are spaced from each other.

Although not shown, an integrated circuit including circuits for the light source 13 and the light receiver 14 is formed on the chip substrate 12, and the chip substrate 12 is connected via bumps 15 which also serve as connection terminals. The optical substrate 11 is fixed to a printed wiring portion (not shown) formed on one flat surface 11a.

The light source 13 emits signal light having a wavelength of, for example, 1.55 μm, which has a high translucency with respect to the chip substrate 12. The optical substrate 11 may be made of a material having a high light-transmitting property with respect to the wavelength of the signal light, other than ordinary glass and quartz, for example, a silicon substrate or the like.

On one flat surface 12a of the chip substrate 12,
First condenser lens 1 receiving spherical divergent light from light source 13
6 is formed so as to be located immediately below the light source 13. A second condenser lens 17 is formed on one flat surface 12 a of the chip substrate 12 so as to be located immediately below the light receiver 14.

Further, one flat surface 12 of the chip substrate 12
a pair of deflecting means 18 and 19 are formed between the condenser lenses 16 and 17,
Between 8 and 19, an auxiliary reflecting means 20 is formed. On the other flat surface 11b of the optical substrate 11, a reflection means 21 for covering the flat surface is formed. The auxiliary reflection means 20 and the reflection means 21 can be formed of a metal thin film such as aluminum.

The first condenser lens 16 is, as shown in FIG.
The divergent spherical light from the light source 13 is converted into a parallel luminous flux, and the one flat surface 11
The CGH element guides the parallel light beam angularly into the optical substrate 11 from a to the other flat surface 11b on the opposite side.

The optical substrate 11 passes through the first condenser lens 16
The parallel light flux guided inside is reflected by the reflection means 21 provided on the other flat surface 11b of the optical substrate 11 so that the incident angle and the reflection angle have the same value (angle θ1). , And enters the first deflecting means 18.

In the example shown, the deflecting means 18 comprises a CGH element as in the first condenser lens 16,
The incident light is diffracted at an outgoing angle θ2 different from the incident angle θ1, for example, larger than the incident angle θ1.

Due to the diffraction effect of the deflecting means 18, the output angle θ
The light refracted by 2 is reflected again by the reflection means 21 and
The reflected light is incident on the auxiliary reflecting means 20 at an incident angle θ2, and is reflected toward the reflecting means 21 at an outgoing angle equal to the incident angle.

The reflection means 21 receiving the reflected light from the auxiliary reflection means 20 has an emission angle θ2 equal to the incident angle θ2,
Since the parallel light beam is directed to the second deflecting means 19, it is incident on the deflecting means at an incident angle θ2.

The deflecting means 19 comprises a CGH element similar to the deflecting means 18 in the illustrated example. This deflection means 19
Diffracts the parallel light beam incident at the incident angle θ2 toward the reflection means 21 at the same incident angle θ1 as described above, which is a value smaller than the incident angle. From the deflecting means 19, the incident angle θ1
The reflecting means 21 which receives the parallel light beam at (2) directs the parallel light beam to the second condenser lens 17 at an emission angle θ1.

The second condenser lens 17 deflects the final reflected parallel bundle from the reflection means 21 toward the light receiver 14 and condenses the light on the light receiver. The second condenser lens 17 has the same C as in the first condenser lens 16.
It can be constituted by a GH element.

First and second deflecting means 18 and 1
9. The auxiliary reflection means 20 and the reflection means 21 define the zigzag path 22 of the parallel light flux guided into the optical substrate 11 through the first condenser lens 16 as described above. The optical element 1 that defines the path 22 so that the zigzag path 22 has a symmetrical shape with the center line c as the axis of symmetry.
6, 17, 18, 19, 20 and 21 are arranged symmetrically with the center line c as the axis of symmetry.

In the zigzag path 22, the optical substrate 11
The path changes due to the difference in the refractive index between the optical substrate 11 and the atmosphere, which is the external environment. The change in the path is compensated for each time the optical substrate 11 enters and exits, so that the zigzag path 22 is considered. In addition, it is possible to ignore a partial change in the course of the zigzag path 22 due to a difference in the refractive index between the optical substrate 11 and its external environment.

In the optical device 10 according to the present invention, a part of the reflecting means for defining the zigzag path 22 is the deflection means 1.
Since these are constituted by 8 and 19, it is possible to set a large exit angle θ2 (deflection angle) different from the incident angle θ1 to these deflecting means 18 and 19.

Accordingly, by increasing the deflection angle, the number of times of refraction of the zigzag path 22 at the distance between the light source 13 and the light receiver 14 can be reduced, and the reflection loss due to reflection can be reduced. Further, since the distance between the light source 13 and the light receiver 14 can be increased without increasing the number of times of refraction, the degree of freedom in designing the optical device 10 is improved.

Further, in the optical device 10 according to the present invention,
Optical elements such as the first condenser lens 16, the second condenser lens 17, and the deflecting means 18 and 19, whose formation process is more complicated than that of the reflection means, are formed on the chip substrate 12, and 11 merely has a reflection means 21 which is easy to manufacture.

Therefore, the manufacture of the optical substrate 11 is easy, and the incorporation of each of the optical elements 16, 17, 18, and 19 into the chip substrate 12 requires the use of a microscopic device such as an integrated circuit technology. Since the processing technique is applied, it can be performed relatively easily. Therefore, according to the present invention, it is possible to provide an optical device that is relatively easy to manufacture, in addition to being able to increase the degree of freedom of design or reduce optical loss due to reflection in a zigzag path. Can be.

First and second condenser lenses 16 and 1
7 can be formed by a bulk lens other than the CGH element, for example, and the first and second deflecting means 18 and 19 can be formed by deflecting means other than the CGH element, such as a diffraction grating.

However, the condenser lenses 16 and 17
To give the light-collecting function and the deflection function as described above,
In addition to providing the deflecting function to the deflecting means 18 and 19 in addition to the above-mentioned deflecting function, a CGH element is used for the condenser lenses 16 and 17 and the deflecting means 18 and 19. Is desirable.

FIG. 2 shows the deflection means 18 and 1 of the first embodiment.
FIG. 9 is a diagram for explaining a relay lens system constituted by both deflecting means 18 and 19 by adding an imaging function to 9. The pair of deflecting means 18 and 19 are CGH elements having a condensing function in addition to the deflecting function described above.
H elements 18 and 19 have a focal length f. Both CG
The H elements 18 and 19 are arranged so as to satisfy the confocal condition, as shown in FIG.

That is, the CG constituting the first deflection means
The H element 18 is arranged at a focal length f from the first condenser lens 16 so as to receive a parallel light beam from the light source 13 obtained by the first condenser lens 16. Also, the first
The CGH element is arranged such that the focal point of the CGH element 19 constituting the second deflecting means is located at the image forming point of the CGH element 18 constituting the deflecting means. Also, this second
So that the parallel luminous flux passing through the CGH element 19 constituting the deflecting means becomes the incident parallel luminous flux of the second condenser lens 17.
The second condenser lens 17 is arranged at a distance of the focal length f from the GH element 19. The ray determinant of the relay lens system satisfying the confocal condition is shown in FIG.

By forming a relay lens system by the deflecting means 18 and 19, even if a slight divergence occurs in the parallel light beam due to diffraction, the effect of diffraction can be suppressed by the imaging function of the relay lens system. . Therefore, when the influence of diffraction is strong, for example, when the aperture of each of the lenses 16 and 17 is a small-diameter lens of several hundred microns or less, it is desirable that one deflection means 18 and 19 constitute the above-mentioned relay lens system.

Hereinafter, a manufacturing procedure of the CGH element will be schematically described. CAD is used for manufacturing the CGH element, and a phase difference function of light in the CGH element exhibiting desired diffractive optical characteristics is obtained. This phase difference function is
It is called an optical path difference function ρ (x, y). Optical path difference function ρ
(X, y) is converted into a polynomial represented by the following equation: ρ (x, y) = ΣCNxmyn (1) This polynomial (CNxmy
The coefficient CN of n) is called an optical path difference coefficient. n and m are positive integers, respectively, and the coefficient CN is also called a phase coefficient. The following equation is established between N and m, n: N = {(m + n) 2 + m + 3n} / 2 (2)

The optical path difference coefficient CN 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 mask necessary for obtaining a desired shape by photolithography is obtained. 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 10 or less and N is 65 or less is given from the relation of the capacity of data processing. Accordingly, an optical path difference function ρ (x, y) showing desired optical characteristics is obtained, and each optical path difference coefficient CN (C0 to C0) of the optical path difference function ρ (x, y) is obtained.
After obtaining 65), the data can be input to a CAD program to obtain a mask pattern for a CGH element exhibiting desired diffractive optical characteristics.

Each of the phase coefficients C0 to C65 can be 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 an approximate expression up to the tenth-order term. .

Therefore, in manufacturing a CGH element, first, an optical path difference function ρ (x, y) showing desired optical characteristics is obtained. From this optical path difference function ρ (x, y), optical path difference coefficients, that is, phase coefficients C0 to C65 are obtained, and these values are input to the above-mentioned CAD program to obtain a computer generated hologram exhibiting a desired diffractive optical characteristic. Can be obtained. Along this mask pattern,
A required number of masks are manufactured, and a lens material is etched by a photolithography method using a combination of these masks.
An element is obtained.

Next, an example in which the first condenser lens 16 is formed by a CGH element will be schematically described. FIG. 4 shows the optical characteristics of the first condenser lens 16. First condenser lens 16
Has a deflecting function as well as a collimating function for converting spherical divergent light from the light source s into a parallel light flux when disposed at a distance L from the light source s, as described above.

Accordingly, as shown in FIG. 4, the first CGH element 16 serving as the first condenser lens 16 converts the divergent spherical wave from the point light source s on the z-axis into a desired light vector component ( α, β, γ) into a parallel light beam, and a point light source s
Is considered to exist at a position separated by a distance L from the origin on the Z axis. The optical path difference function ρ of the first CGH element 16
(X, y) is given by the following equation.

Ρ (x, y) = (x2 + y2 + L2) 1 / 2−L− (αx + βy) / (α2 + β2 + γ2) 1/2 (4) In equation (4), L is This is the distance from the light source to the origin, and is equal to the focal length f1 of the first condenser lens 16. This equation (4)
Is substituted into the equation (3), and the first CGH element 16 is executed by executing a CAD program using the optical path difference coefficient obtained by the substitution, that is, the phase coefficient CN.
Can be obtained, and the photolithography and the etching process using the mask form the first C on the one plane 12a of the chip substrate 12.
The GH element 16 is formed. In addition, the CGH element 16
Second CGH element 16 which is a second condenser lens equivalent to
Can be similarly formed.

Next, the optical characteristics of the third CGH element 18 as the deflecting means 18 will be described with reference to FIG. As shown in FIG. 5, the third CGH element 18 constituting the relay lens system has a deflecting function of converting a divergent spherical wave from the point light source s into a parallel light beam. In addition to this deflection function,
As described above, it has a light collecting function of collecting light at the focal length f.

The third CGH element 18 is arranged on the xy plane such that its center coincides with the z axis, and the coordinates (X,
Assuming that the divergent light from the point light source s located at (Y, Z) is converted into a parallel light flux represented by a vector component (α, β, γ) passing through the origin, the optical path difference of the third CGH element 18 The function ρ (x, y) is given by

Ρ (x, y) = ｛(Xx) 2+ (Yy) 2 + Z2)｝ 1 / 2-f- (αx + βy) / (α2 + β2 + γ2) 1/2 (5) Indicated by Here, the distance f from the origin to the point light source s
Is represented by the following equation. f = (X2 + Y2 + Z2) 1/2 (6)

Therefore, as in the case of the first CGH element 16 described above, the phase coefficient CN obtained by substituting equation (5) into equation (3) is used to execute the same CAD program as described above. By execution, mask data for the third CGH element 18 can be obtained, and a photolithography and etching process using the mask forms one side of the relay lens system on one plane 12a of the chip substrate 12. The third CGH element 18 which is the deflecting means can be formed. Further, a fourth CGH element 19, which is the other deflection means equivalent to the CGH element 18, can be formed in the same manner.

As described above, the condensing lenses 16 and 17 and the deflecting means 18 and 19 are constituted by the above-mentioned CGH elements, so that an optical element having a complicated function combining the condensing function and the deflecting function is provided. 16 to 19 can be relatively easily incorporated into the chip substrate 12 by photolithography and etching techniques.

The deflection means 18 and 19 comprising a pair of CGH elements constituting a relay lens system are connected to a zigzag path 22.
A single relay lens system 1 instead of
A so-called hybrid configuration in which a plurality of zigzag paths 22 are collectively handled by 8 and 19 can be provided.
In addition, the deflecting means 18 and 19 do not have a condensing function,
It can be constituted by a CGH element having only a prism function, that is, a diffraction function.

<Embodiment 2> FIG. 6 shows Embodiment 2 of the optical device 10 according to the present invention. In the specific example 1 shown in FIG.
The example in which the light source 13 and the light receiver 14 are arranged on a single chip substrate 12 is shown. Instead, as shown in FIG. 6, the chip substrate 12 is divided into first and second chip substrates 12.
A and 12B.

In the second embodiment, the light source 13 and the spherical divergent light from the light source are converted into a parallel light beam, and the optical substrate 1 is angled.
A first condensing lens 16 for guiding the light into the light source 1 and a reflecting means 21
The first deflecting means 18 for diffracting the reflected light from the first chip substrate 12A is provided on the first chip substrate 12A. The chip substrate 12A is coupled to the plane 11a of the optical substrate 11 via the same bumps 15 as in the first embodiment.

On the other hand, the second deflecting means 19 receives the diffracted light from the deflecting means as reflected light from the reflecting means 21,
The second condenser lens 1 for guiding the reflected light to the light receiver 14
7 are provided on the second chip substrate 12B. This second chip substrate 12B is made up of the first chip substrate 12A
In the same manner as described above, it is coupled to the plane 11a of the optical substrate 11.

In the second embodiment, the auxiliary reflection means 20 is provided on the plane 11a of the optical substrate 11 opposite to the plane 11b on which the reflection means 21 is provided. Therefore, the reflection means 20 and 21 are formed on both surfaces 11a and 11b of the optical substrate 11. However, such a reflection means can be formed relatively easily, for example, as compared with the formation of a metal film as described above using a vapor deposition technique.

Thus, as in the first embodiment, in the second embodiment, it is not necessary to form a complicated optical element on the optical substrate 11, and the optical device 10 can be formed relatively easily.

In the optical device 10 of the second embodiment, since the light source 13 side and the light receiver 14 side are separated into two chip substrates 12A and 12B, the single chip substrate 12 shown in the first embodiment is separated. It can be relatively easily applied to a large distance between the light source 13 and the light receiver 14, which is not easy to realize.

[0056]

As described above, in the optical device according to the present invention, it is not necessary to incorporate complicated optical elements such as a condenser lens and a deflecting means into the optical substrate, and the first device for guiding light to the optical substrate. A condensing lens, a second condensing lens for guiding light from the optical substrate to the light receiver, and a deflecting means for increasing the degree of freedom of design or reducing optical loss due to reflection in a zigzag path, Since it is incorporated in a chip substrate to which the microfabrication technology is applied, the condenser lens and the deflecting means can be incorporated relatively easily and with high accuracy.

Therefore, according to the present invention, in addition to increasing the degree of freedom of design or reducing the optical loss due to reflection on the zigzag path, an optical device which is relatively easy to manufacture can be obtained. Can be provided.

[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 of a relay lens system.

FIG. 3 is an explanatory diagram of a Taylor expansion formula.

FIG. 4 is an explanatory diagram showing optical characteristics of a first condenser lens.

FIG. 5 is an explanatory diagram illustrating optical characteristics of a deflection unit.

FIG. 6 is a sectional view schematically showing Example 2 of the optical device according to the present invention.

[Explanation of symbols]

 Reference Signs List 10 optical device 11 optical substrate 12 (12A, 12B) chip substrate 13 light source 14 light receiver 16, 17 condensing lens 18, 19 deflecting means 20, 21 reflecting means 22 zigzag path

Claims (5)

[Claims] 1. An optical substrate for transmitting light, a light source for an optical signal, and a light receiver for receiving an optical signal spaced from the light source, and one surface of the optical substrate. A first condensing lens that guides light from the light source into the optical substrate, and a light guide that is provided on the optical substrate and guides the light guided into the optical substrate. Reflecting means for reflecting the light toward the one surface of the substrate; deflecting means for defining a zigzag path through the optical substrate in cooperation with the reflecting means; and receiving the light passing through the zigzag path. A second condenser lens for guiding the first condenser lens and the second condenser lens, and the deflecting means are provided on the chip substrate. An optical device, characterized in that: 2. The semiconductor device according to claim 1, wherein the chip substrate has a pair of surfaces parallel to each other and one surface of which is opposed to the optical substrate, and has a property of transmitting light from the light source. A light source and a light receiver are provided on the other surface of the semiconductor substrate, with their respective functional surfaces facing the one surface of the semiconductor substrate. 2. The optical device according to claim 1, further comprising first and second condenser lenses and said deflecting unit. 3. The first and second condenser lenses,
The optical device according to claim 1, wherein the optical device is a CGH element having a condensing function and a deflecting function, and the deflecting unit is a CGH element having a deflecting function. 4. A pair of deflecting means each having a deflecting function and forming a confocal relay lens system with each other.
The optical device according to claim 1, comprising a GH element. 5. The optical device according to claim 1, wherein the chip substrate is separated into a first chip including the light source and a second chip including the light receiver.