JP2000028838A - Optical module for signal transmission and reception - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module for signal transmission and reception which is small in size and is free in shapes. SOLUTION: This optical module comprises a microlens array 11 which is obtd. by forming plural microlenses 13 of short focal lengths disposed in juxtaposition on the surface of a lens substrate 12 and focus the foal positions of the respective microlenses 13 to the rear surface of the substrate 12 and an optical waveguide substrate part 16 which is superposed on this microlens array part 11 in the state of joining the rear surface of the waveguide substrate 4 to the rear surface of the lens substrate 12 and is formed with a Y branch waveguide 15 for branching and combining input and output light at the waveguide substrate 14. The Y branch waveguide 15 is extended to the focal positions in the form that its respective branch side ends are respectively aligned to the optical axes of the respective microlenses 13. The combining side end thereof is extended to the front surface or flank of the waveguide substrate 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting / receiving optical system for splitting or multiplexing light used in an optical communication system.
In particular, so that it can be miniaturized and take any shape,
The present invention relates to a transmitting / receiving optical module in which a microlens array and a Y-shaped optical waveguide are combined.

[0002]

2. Description of the Related Art In a transmission / reception optical system of this kind, as shown in FIG. 1, an objective lens 1 and a photoelectric conversion element 2 composed of a light emitting element or a light receiving element arranged at a focal position thereof are combined to transmit or receive light. Transfer is performed between the objective lens 1 and the photoelectric conversion element 2.

In this transmission / reception optical system, an objective lens 1 having an aperture D required to secure a predetermined transmission beam width and a received light amount is used. A distance interval corresponding to the focal length L is required, and a housing 3 for accommodating and fixing and holding them is required.

[0004] For example, if the diameter D of the objective lens 1 is 40 mm
When the F number is a general value of 2 in φ, the focal length L is 40 mm × 2 = 80 mm, and the light focusing area is 12.6 cm.
Since the ^2, as well as a required long distance interval of 80mm between the objective lens 1 and the photoelectric conversion element 2, also increases the volume of the housing 3 that accommodates these, the focal length L for this improvement short If the f-number is reduced as described above, the aberration increases and the performance decreases, which is not desirable.

[0005] In the case of a receiving optical system, in order to reduce the temporal fluctuation of the receiving intensity based on the temporal fluctuation of the refractive index distribution of the atmosphere (known as a cause of star blinking),
In some cases, a so-called aperture averaging effect is obtained by increasing the aperture of the objective lens or extracting the sum of a plurality of receiving optical systems provided side by side at an interval.

[0006]

As described above, the transmitting / receiving optical system in which the objective lens 1 and the photoelectric conversion element 2 according to the prior art are combined requires a long focal length L, and
It has been difficult to reduce the size of the device because, for example, there is a possibility that the outer periphery of the cylindrical optical path formed during that time becomes a dead space and cannot be used effectively.

In order to obtain the aperture averaging effect, when the aperture of the objective lens is increased, the focal length L is further increased. When a plurality of receiving optical systems are arranged in parallel, there is no flexibility in the arrangement of the lenses. The space utilization efficiency is further deteriorated, and miniaturization of the device becomes more difficult.

Therefore, the present invention solves these problems of the prior art, and it is possible to reduce the size of the apparatus by shortening the focal length, and it is possible to take a free shape to save space. It is an object of the present invention to provide a novel optical module for transmitting and receiving, which can design a device having a degree of freedom by effectively utilizing it and adopt an effective proper arrangement for obtaining an aperture average effect.

[0009]

A transmitting / receiving optical module according to the present invention is an optical system for receiving or transmitting a spatially propagating light wave, and includes a plurality of microlenses having a short focal length arranged in parallel on a surface of a lens substrate. A microlens array portion formed and aligned with the focal position of each microlens on the back surface of the lens substrate, and a microlens array portion superimposed on the microlens array portion in a state where the back surface of the waveguide substrate is bonded to the back surface of the lens substrate. And an optical waveguide substrate portion formed with a Y-branch waveguide for branching and merging the input / output light, wherein the Y-branch waveguide has a branch-side end portion coinciding with the optical axis of each microlens. At the focal position, and
The junction side end extends to the surface or side surface of the waveguide substrate.

In the transmission / reception optical module of the present invention having the above-described structure, when used for reception, light incident on each microlens is condensed at each focal position, and then sequentially merged in an optical waveguide to form a waveguide substrate. When the received light synthesized from the merging side end of the surface is radiated to the receiving part and used for transmission, the light incident from the merging side end is sequentially branched in half by the optical waveguide at the branch side. The focal position of each microlens, which is the end, is reached, and transmission light by a plurality of narrow light beams is emitted from the microlens into the air.

In the optical module for transmission and reception according to the present invention, a microlens array and an optical waveguide substrate are used instead of one objective lens, and the light of each microlens having a short focal length is branched and merged by the Y-branch optical waveguide. As a result, the restriction of miniaturization due to the thickness corresponding to the focal length of the objective lens of the conventional optical system is eliminated, and a thin optical system can be realized, which contributes to the miniaturization of the optical transceiver.

Also, unlike an objective lens which is limited to a circular cross section and has a dead space on the outer periphery of a cylindrical optical path up to the focal position, the shape of the microlens array and the arrangement of the microlenses can be freely set. Since the branched optical waveguide can be formed in the thin optical waveguide substrate, there is an effect that the space efficiency when incorporated in the device is improved and the degree of freedom in device design is improved.

Further, the shape of the microlens array and the arrangement of the microlenses are set to an appropriate arrangement (so that reception points are set at a plurality of different places) effective for obtaining an aperture average effect, and the reception intensity Fluctuations can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a transmitting / receiving optical module according to the present invention will be described with reference to FIGS.
8, FIG. 2 is a schematic view of the optical module for transmission and reception, (a) is a plan view, (b) is a longitudinal sectional view, and FIG. 3 is an enlarged main part of the optical module for transmission and reception. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3 and shows a cross-sectional view according to the first embodiment.
FIG. 6 is a cross-sectional view taken along the line IV-IV, showing a cross-sectional view according to a second embodiment, and FIG. 6 is an example view in which a transmitting / receiving optical module according to the present invention is used for lighting a wall-mounted painting;
FIG. 7 shows an embodiment of various types of optical modules, and FIG. 8 shows an embodiment of a method of transmitting and receiving signals by a parallel connection type.

Optical module 1 for transmission and reception according to the present invention
Numeral 0 denotes an optical system for receiving or transmitting a spatially propagating light wave. As shown in FIG. 2, a plurality of microlenses 13 having a short focal length are formed side by side on the surface of a lens substrate 12, and each microlens 13 Focus position of the lens substrate 12
The microlens array unit 11 aligned with the back surface of the substrate and the microlens array unit 11 are overlapped with the back surface of the waveguide substrate 14 joined to the back surface of the lens substrate 12, and input / output light is branched to the waveguide substrate 14. .Y-branch waveguide 15 to be joined
And the optical waveguide substrate portion 16 formed with the above.

The microlens array unit 11 is formed of a molding resin material having optical characteristics such as polycarbonate (PC) having excellent transparency and polymethyl methacrylate (PMMA) having good light transmittance, and is poured into a mold. A large number of microlenses 13 can be integrally formed on the lens substrate 12 by a method such as that described above, and the lens substrate 12 can be formed in a square, circular or other planar shape. When a plurality of lens substrates 12 are juxtaposed, it is particularly desirable to form them into a square shape.

As for the arrangement of the micro lenses 13 on the lens substrate 12, a desired number can be arranged for each row X along the horizontal direction and each stage Y along the vertical direction. It is also possible to arrange all the micro lenses 13 on one lens substrate 12, or to arrange the lens substrates 12 in each stage Y in a dispersed state separated from each other. The aperture, arrangement and number of each lens are set so as to obtain the condensing area.

In the micro-lens array section 11 arranged as shown in FIG.
Assuming that the distance between the lenses 13 is 5 mm in mmφ, the focusing area per lens is 0.196 cm ² ,
When 64 lenses are arranged, the total light collecting area is 0.19
6 × 64 = 12.5cm ^2, and becomes the same light collecting area and the objective lens 1 according to the prior art described earlier.

The optical waveguide substrate section 16 is connected in series and in parallel with a 1 × 2 Y branching / combining unit as a unit, and is provided with a waveguide necessary for performing desired branching or merging with respect to transmission light or reception light. The Y-branch waveguide 15 having the waveguide pattern is connected to the waveguide substrate 1.
4 and each branch-side end is connected to each microlens 13.
Of the photoelectric conversion element 17 that is arranged adjacent to the outside while extending to the focal position F in a manner coinciding with the optical axis C of the
The transmission and reception of an optical signal is performed between the device and.

The optical waveguide substrate section 16 has a Y-branch waveguide 15 formed by, for example, thermally diffusing titanium into a waveguide substrate 14 made of a silicon substrate or the like. Are fixed by an optical adhesive.

The Y-branch waveguide 15 has a tree structure connected in a tournament system like the Y-branch waveguide 15A in the waveguide substrate 14A of FIG. 5, a variety of waveguide patterns suitable for use, such as a Y-branch waveguide 15B in the waveguide substrate 14B, in which a merging side is connected in a chain and a merging side end is arranged on a side surface. It is possible to

The Y-branch waveguides 15A shown in FIG. 4 are each composed of eight microlenses 1 arranged in rows X for each stage Y.
For 3X1 to 13X8, the respective branch-side ends 15A1 to 15A8 of the eight optical paths extending on the back surface of the waveguide substrate 14A.
Are arranged perpendicular to the optical axes C of the corresponding microlenses 13X1 to 13X8 and aligned with the focal position F,
The waveguides are sequentially merged in a tree shape with two optical paths as one set, and finally extend to the surface of the waveguide substrate 14A as the merging side end 15A0 of one optical path.

When the Y-branch waveguide 15A is used for reception, light incident on each microlens 13 is focused on each focal position F
After being condensed, the light was sequentially merged in the optical waveguide, and the received light synthesized from the merging side end of the surface of the waveguide substrate 14 was radiated to the receiving portion, and when used for transmission, it was incident from the merging side end. The light reaches the focal position F of each microlens 13 which is a branch-side end while sequentially branching in half at the optical waveguide,
Transmission light by a plurality of narrow light beams is emitted from the microlenses 13 into the air.

As in the case of the Y-branch waveguide 15A, the Y-branch waveguide 15B shown in FIG. 5 has eight optical paths extending on the back surface of the waveguide substrate 14B, and the respective branch-side ends 15B1 to 15B of the eight optical paths.
8 are arranged perpendicular to the respective optical axes C of the corresponding microlenses 13 and in alignment with the focal position F.
The optical paths are joined in a chain and extended to the side surface of the waveguide substrate 14B as a joining end 15B0 of one optical path.

When the Y-branch waveguide 15B is used for reception, the light incident on each microlens 13 is condensed at each focal position F as in the case of the Y-branch waveguide 15A, and then the optical waveguide And the combined light is emitted from the merging side end of the side face of the waveguide substrate 14 to the receiving portion, and an optical module having a thickness smaller than that of the Y-branch waveguide 15A is formed. When used, the light incident from the converging side end is sequentially branched into halves in the optical waveguide, so that the farther away from the converging side end the microlens 13 is, the smaller the amount of emitted light is and the radiation density is reduced. Since a gradient is generated, it is preferable to use this characteristic for a special purpose.

For example, in FIG. 6, the Y branch waveguide 15B
An example is shown in which the optical module 20 is used to illuminate a wall-hanging painting. In the case of a painting 22 hung on a wall 21, it is desirable to illuminate uniformly from an obliquely upper position, and the microlens 13 near the merging side end is preferred. 21 with synchrotron radiation from
When the Y-branch waveguide 15B is used to illuminate the lower end of the light source, the lower end farther away is irradiated by the microlens having a higher density of light from the radiation source, and the upper end closer to the light is closer to the light density of the radiation source. Are illuminated by the irradiation light of the microlenses, respectively, so that uniform illumination can be performed.

The transmission / reception optical module comprises a housing 1
9, a photoelectric conversion element 17 disposed adjacent to the optical waveguide substrate section 16 on the optical axis at the end of the Y-branch waveguide 15 on the merging side, and effectively transmitting and receiving light by reducing loss. A relay lens 18 (for example, a spherical ball lens or the like) to be mounted as necessary is used in combination for the purpose of performing, and the photoelectric conversion element 17 and the relay lens 18 may be disposed and mounted on the waveguide substrate 14. it can.

As the photoelectric conversion element 17, a light emitting element such as a light emitting diode or a laser diode is used for transmission, and the transmission light converted into an optical signal by the light emitting element is branched by the optical waveguide substrate section 16 to be a micro lens. The light is transmitted from the array unit 11, and in the case of reception, a light receiving element such as a silicon photodiode is used, and the received light received by the microlens array unit 11 and combined by the optical waveguide substrate unit 16 is converted into an electric signal and extracted.

As described above, in the transmitting / receiving optical module according to the present invention, a plurality of microlenses 1 having a short focal length are provided.
The thin and small transmitting optical system or the receiving optical system is composed of the microlens array section 11 having the 3 formed therein and the optical waveguide substrate section 16 having the Y-branch waveguide 15 for branching and merging the input / output light. Therefore, as is clear from comparison between FIG. 1 and FIG. 2, the size of the entire apparatus can be reduced, and
Since the dead space is small, the degree of freedom in designing when arranging components is also increased.

As shown in FIG. 7A, a desired number and arrangement of all the microlenses 13 can be arranged along a row X and a column Y on an integrated optical module 23 as shown in FIG. It is good, but as shown in FIG. 7B, the module divided for each stage is used in the state of the optical module 24 in which a required number is combined, or as shown in FIG. The module can be used in the state of the modules 25, 25, and there is a form in which either or both of the microlens array unit 11 and the optical waveguide substrate unit 16 are divided.

When used in the state shown in FIG. 7B, there is an advantage that the workability in manufacturing is good and the degree of freedom in designing is increased. When used in the state shown in FIG. Are arranged in a dispersed manner, so that it is easy to obtain reception points under different conditions even with the same light-collecting area, so that an aperture averaging effect can be particularly expected.

As one of the methods of transmitting and receiving signals between the end of the optical waveguide 15 on the optical module side and the photoelectric conversion element 17 on the electric circuit side, input / output divided for each column is used. There is an independent separation type that individually transmits light, and in the independent separation type, a light emitting element and its driving circuit in the case of transmission, a light receiving element and its amplification circuit in the case of reception are provided for each column, In addition, in the case of reception, an addition circuit for adding the output received and amplified for each column is provided.

As another transmission / reception method, there is a parallel connection type in which input / output light divided for each stage is transmitted collectively. In this parallel connection type, as shown in FIG. A coupling substrate 27 having a second Y-branch waveguide 26 formed therein and a second Y-branch waveguide 28 which forms a second Y-branch waveguide 28 branching and merging in the same manner as the optical waveguide 15 </ b> B are introduced into the conductive substrate 27. Waveguide substrate 14A or waveguide substrate 14B
And are integrally connected by an adhesive means or the like.

The second Y-branch waveguides 26 and 28 have their branch-side ends extended to one ends of the connection substrates 27 and 29 to be aligned with the merging-side ends 15A0 and 15B0 of the waveguide substrates 14A and 14B. At the same time, the merging-side end portions 26a and 28 extended to the surface of the waveguide substrate 14A or the side surface of the waveguide substrate 14B.
b, transmitting and receiving signals to and from the photoelectric conversion element 17 to branch transmission light to each stage in the case of transmission.
In the case of receiving, the received light from each stage is merged.

The independent connection type has a performance advantage that the receiving sensitivity is higher and the S / N ratio is improved as compared with the parallel connection type. Unlike the independent connection type, the parallel connection type has a light emitting element for transmission. And its driving circuit, as well as the light receiving element and its amplifying circuit in the case of reception, are economically advantageous in that they can be combined into one set. For example, when there is sufficient reception strength, a parallel connection type is used. Can be used properly.

[Brief description of the drawings]

FIG. 1 is a schematic view of a transmission / reception optical lens system according to a conventional example, in which (a) is a plan view and (b) is a longitudinal sectional view.

FIGS. 2A and 2B are schematic diagrams of a transmission / reception optical module to which the present invention is applied, wherein FIG. 2A is a plan view and FIG.

FIG. 3 is an enlarged plan view of a main part of the optical module for transmission and reception in FIG. 2;

FIG. 4 shows a sectional view according to the first embodiment along the line IV-IV in FIG. 3;

5 shows a sectional view according to a second embodiment along the line IV-IV in FIG. 3;

FIG. 6 shows an embodiment in which the transmission / reception optical module according to the present invention is used for lighting a wall-mounted picture.

FIGS. 7A and 7B show examples of various embodiments of the optical module for transmission and reception according to the present invention.

FIG. 8 is a diagram showing an embodiment of a method of transmitting and receiving signals by a parallel connection type in the optical module for transmission and reception according to the present invention.

[Explanation of symbols]

 Reference Signs List 10, 20, 23, 24, 25 Optical module 11 Micro lens array unit 12 Lens substrate 13 Micro lens 14 Waveguide substrate 15 Y branch waveguide 16 Optical waveguide substrate unit 17 Photoelectric conversion element 18 Relay lens 19 Housing 21 Wall 22 Painting 26 , 28 Second Y-branch waveguide 27, 29 Connecting substrate

Claims (1)

[Claims] 1. An optical system for receiving or transmitting a spatially propagating light wave, wherein a plurality of microlenses having a short focal length are formed side by side on a surface of a lens substrate, and a focal position of each microlens is set on the lens substrate. A micro-lens array section aligned with the back side and a Y-branch guide that superimposes the micro-lens array section with the back side of the waveguide substrate bonded to the back side of the lens substrate, and branches and joins the input / output light to the waveguide substrate. The Y-branch waveguide is formed at a focal position in such a manner that each branch-side end coincides with the optical axis of each microlens.
An optical module for transmission and reception, wherein the end on the converging side extends on the surface or side surface of the waveguide substrate.