JP2003075690A - Transmitter and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter and a receiver in which coupling efficiency is improved. SOLUTION: A transmitter A is equipped with a light emitting diode 1, a reflector 2 and a condensing lens 3a, while a receiver B is equipped with a photodiode 8, a reflector 10 and a condensing lens 9a. The transmitter A has the ability of increasing the quantity of light to be emitted within the acceptance angle to the core F1 end face of an optical fiber F and improving the coupling efficiency in which a light beam from the light emitting diode 1 is coupled with the core F1 end face of the optical fiber F. The receiver B has the ability of increasing a light quantity to be emitted to the photodiode 8 and improving the coupling efficiency in which a light beam outgoing from the core F1 end face of the optical fiber F is coupled with the photodiode 8.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transmitter and a receiver for transmitting and receiving an optical signal via an optical fiber.

[0002]

2. Description of the Related Art Conventionally, transmitters and receivers for transmitting and receiving optical signals via optical fibers have been provided.

The transmitter includes a light emitting diode that emits light as an optical signal, and the receiver includes a photodiode.

In such a transmitter and a receiver, respectively, the light emitting portion of the light emitting diode is substantially opposed to one end surface of the optical fiber, and the light receiving portion of the photodiode is substantially opposed to the other end surface of the optical fiber. Both ends are connected via optical connectors.

Then, by causing the light emitting diode of the transmitter to emit light, the light from the light emitting diode enters the core of the optical fiber as an optical signal from one end face of the optical fiber, and is repeatedly reflected at the interface between the core and the clad. The light transmitted to the other end face and emitted from the other end face is received by the photodiode of the receiver as an optical signal.

[0006]

However, in the above-mentioned conventional transmitter and receiver, the coupling efficiency of coupling the light from the light-emitting diode of the transmitter to the core end face of the optical fiber and the light emitted from the core end face of the optical fiber are reduced. There is a problem that the coupling efficiency of coupling to the photodiode of the receiver is low.

For example, in a transmitter, when a plastic optical fiber having NA (numerical aperture) = about 0.5 is used as the optical fiber and light from the light emitting diode is directly coupled to the end face of the core of the optical fiber, the light emitting diode is used. The emission distribution of is generally a Lambertian distribution (half-value angle of about 120
Is about 6 ° from the optical axis of the emitted light.
The light in the range of 0 ° is applied to the end face of the core of the optical fiber, but only the light in the range of the light receiving angle (about 30 °) corresponding to the NA is incident on the core of the optical fiber and is transmitted. Is represented by the solid angle ratio (1-cos 30 °) /
It is as low as (1-cos 60 °) ≈27%, and this value becomes the theoretical limit of direct coupling.

Further, as the distance from the light emitting diode to the end face of the optical fiber in the transmitter increases,
Since the amount of light radiated to the core end surface of the optical fiber within the range of the light receiving angle according to NA is reduced, the coupling efficiency is further reduced. Similarly, also in the receiver, the longer the distance from the end face of the optical fiber to the photodiode, the smaller the amount of light emitted to the light receiving portion of the photodiode, and thus the coupling efficiency further decreases. Therefore, the transmitter and the receiver are required to have a structure for accurately aligning each end face of the optical fiber with the light emitting diode or the photodiode.

The present invention aims to solve the above problems, and provides a transmitter and a receiver with improved coupling efficiency.

[0010]

In order to achieve the above object, the invention of claim 1 is a transmitter for transmitting an optical signal through an optical fiber, and emits light which becomes the optical signal. A light emitting element, a reflector that reflects at least a part of the light emitted from the light emitting element and directs it toward the end face of the optical fiber, and collects at least a part of the light emitted from the light emitting element onto the end face of the optical fiber. Of the light from the light emitting element, the light outside the range of the light receiving angle corresponding to the numerical aperture of the optical fiber, or the light directed in a direction different from the end face of the optical fiber, By reflecting the light onto the reflector, condensing the light onto the condenser lens, and directing the light toward the end face, the amount of light irradiated to the end face of the optical fiber within the range of the light receiving angle is increased, and the light from the light emitting element is converted into light. fiber It is possible to improve the coupling efficiency for coupling to the end surface.

The invention of claim 2 is characterized in that, in the invention of claim 1, a plurality of condenser lenses are provided, and more light from the light emitting element can be condensed and directed to the end face of the optical fiber. Therefore, the coupling efficiency can be further improved.

According to a third aspect of the present invention, there is provided a receiver for receiving an optical signal transmitted through an optical fiber, wherein at least a light receiving element and light emitted from the end face of the optical fiber as the optical signal. A light-receiving element, and a reflector for reflecting light that is not condensed by the light-collecting lens among the light emitted from the end face and directs the light toward the light-receiving element. , At least a part of the light emitted from the end face of the optical fiber and directed in a direction different from that of the light receiving element is condensed by the condensing lens, and the light that is not condensed by the condensing lens in the light directed in the different direction is By increasing the amount of light applied to the light receiving element by reflecting the light toward the light receiving element by reflecting the light onto the light receiving element, the coupling efficiency of the light emitted from the end face of the optical fiber to the light receiving element is improved. Door can be.

The invention of claim 4 is characterized in that, in the invention of claim 3, a plurality of condenser lenses are provided, and more light emitted from the end face of the optical fiber is condensed and directed to the light receiving element. Therefore, the coupling efficiency can be further improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) As shown in FIGS. 1 (a) and 2, a transmitter of the present embodiment has a light emitting diode 1 for emitting light as an optical signal and a light emitting diode 1 for emitting light. The optical fiber F by reflecting part of the reflected light
Of the core F1 of the optical fiber F, and a part of the light emitted from the light emitting diode 1 toward the end face of the core F1 of the optical fiber F.
The transparent member 3 having a condenser lens 3a for condensing light on the end face.

The light emitting diode 1 is a light emitting diode for optical communication composed of a semiconductor element, is formed in a substantially rectangular shape, and has a substantially circular light emitting portion 1 provided on one surface.
For example, light in the visible to infrared region is emitted from a. The light emitting diode 1 may be a surface emitting type, an edge emitting type, or any other type, and a type that emits light not only from the one surface but also from the other surface may be used.

The reflector 2 is formed in a thick disk shape having a recess 2a on one surface, and the recess 2a has an opening cross-sectional area that gradually decreases from the opening surface side toward the bottom surface 2b side. The light emitted from the light emitting diode 1 is reflected on the inner surface of the recess 2a. In addition, the reflector 2
A groove 2d is further provided in the peripheral portion of the recess 2a. Further, the reflector 2 is formed with a wiring pattern for electrically connecting to the light emitting diode 1 and causing the light emitting diode 1 to emit light, and the groove portion 2d is provided with a wire bond pad 2c for connecting with the wiring pattern. . Then, the light emitting diode 1 is fixed to a substantially central portion of the bottom surface 2b of the recess 2a with the light emitting portion 1a facing the opening surface side.

The light-transmissive member 3 is located inside the recess 2a and the groove 2d of the reflector 2 to seal the light emitting diode 1 and the reflector 2 is located on the opening side of the recess 2a. A substantially disk-shaped plate portion 3c wider than the stop portion 3d,
It is composed of a peripheral wall 3b protruding from the peripheral edge of the plate portion 3c to the side opposite to the reflector 2 and the above-mentioned condenser lens 3a, and is integrally formed of a translucent resin.

The condenser lens 3a is a spherical lens,
The plate portion 3c is formed at a substantially central portion of the opening surface of the recess 2a of the reflector 2 so as to project from the surface of the plate portion 3c opposite to the reflector 2.

The condenser lens 3a is not limited to a spherical lens, and may be an aspherical lens.

Here, the transmitter A from the light emitting diode 1, the reflector 2 and the light transmitting member 3 as described above.
The procedure for manufacturing the will be described.

First, the reflector 2 is molded with a resin material,
Copper plating is applied to the surface of the reflector 2. Then, an unnecessary portion is removed from the copper plating by, for example, a laser beam or the like to form a pattern on the bottom surface 2b of the recess 2a of the reflector 2, etc., and nickel plating is performed on the formed pattern, and then gold plating is performed. The above wiring pattern is formed by applying. This wiring pattern enhances the reflectance of the reflector 2 to form the highly efficient reflector 2. Then, the wire bond pad 2c is provided in the groove 2d.

Next, the light emitting diode 1 is die-bonded on the bottom surface 2b with a conductive adhesive such as silver paste, so that the electrode on the surface opposite to the light emitting portion 1a of the light emitting diode 1 and the bottom surface 2b are attached. Connect to the formed wiring pattern. Further, the electrode on the surface of the light emitting diode 1 on the side of the light emitting portion 1 a and the wire bond pad 2 c in the groove portion 2 d of the reflector 2 are wire bonded with the gold wire 20.

Here, when both the anode and cathode electrodes of the light emitting diode 1 are on the surface of the light emitting diode 1 on the side of the light emitting portion 1a, the conductive material is not limited to the above-mentioned conductive adhesive, and is non-conductive. The light emitting diode 1 may be bonded to the bottom surface 2b of the recess 2a using an adhesive. Further, in this case, two wire bond pads 2c are provided, and the both electrodes are individually connected to the respective wire bond pads 2c by the gold wires 20.

When both electrodes of the light emitting diode 1 are on the surface opposite to the light emitting portion 1a of the light emitting diode 1, the light emitting diode 1 is mounted on the bottom surface 2b by the flip chip mounting method. At this time, both the anode and cathode electrodes of the light emitting diode 1 are individually connected to the two pad electrodes formed on the wiring pattern on the bottom surface 2b.

Finally, the light-transmissive member 3 is transfer-molded with a light-transmissive resin. At this time, the light emitting diode 1 is sealed by the sealing portion 3d of the translucent member 3,
d, the plate portion 3c, the peripheral wall 3b, and the condenser lens 3a are integrally molded. As a result, transmitter A is completed.

Such a transmitter A of this embodiment
Is connected to the optical fiber F via an optical connector (not shown) so that the light emitting portion 1a of the light emitting diode 1 substantially faces the end face of the optical fiber F with the condenser lens 3a interposed therebetween.
At this time, the opening surface of the recess 2a of the reflector 2 is shaped to face the end surface of the optical fiber F, and the condenser lens 3a is convex toward the end surface of the optical fiber F. Further, since one end of a ferrule (not shown) that supports the optical fiber F is brought into contact with the peripheral wall 3b of the translucent member 3, the distance between the end face of the optical fiber F and the condenser lens 3a is kept substantially constant. The end face of the optical fiber F is positioned.

When light is emitted from the light emitting diode 1, part of the emitted light is outside the range of the light receiving angle corresponding to the NA of the optical fiber F, as in the conventional example.
The light may be directed in a direction different from the end face of the core F1 of the optical fiber F, but such light may be reflected on the inner surface of the recess 2a of the reflector 2 or condensed by the condenser lens 3a to form an end face of the core F1 of the optical fiber F. Optical fiber F
It is possible to increase the amount of light applied to the end face of the core F1 within the range of the light receiving angle, and improve the coupling efficiency of coupling the light from the light emitting diode 1 to the end face of the core F1 of the optical fiber F.

For example, even if the optical fiber F is a plastic optical fiber with NA = about 0.5, the amount of light irradiated to the end face of the core F1 of the optical fiber F within a range of about 30 ° is increased, for example, about 30-. The coupling efficiency can be improved up to 50 [%].

Further, as shown in FIG. 3, the condenser lens 3a
Since the light condensed in step 2 spreads away from the condenser lens 3a, when the end face of the optical fiber F is moved away from the condenser lens 3a and the light emitting diode 1 as shown by the two-dot broken line in FIG. Although the amount of light radiated to the F1 end face is reduced, a part of the light from the light emitting diode 1 is reflected by the reflector 2 toward the core F1 end face side to compensate for the decrease in the amount of light. It is possible to prevent the coupling efficiency from being lowered due to the displacement of the position of and the lengthening of the distance between the end face and the condenser lens 3a and the light emitting diode 1.

As a result, the transmitter A of this embodiment is
Then, positioning of the end face of the optical fiber F does not require high accuracy, and the transmitter A can be easily manufactured. That is, in this embodiment, one end of the ferrule that supports the optical fiber F is attached to the peripheral wall 3b of the translucent member 3 as described above.
Although the end face of the optical fiber F is positioned by contacting the end face of the optical fiber F, one end of the ferrule may not be in contact with the peripheral wall 3b, and the peripheral wall 3b may be omitted from the translucent member 3. is there.

On the other hand, the receiver B of this embodiment is similar to that shown in FIG.
As shown in (b) and FIG. 4, a photodiode 8
A light transmitting member 9 having a condenser lens 9a for condensing at least a part of the light emitted from the end face of the core F1 of the optical fiber F as an optical signal, and the light emitted from the end face. A reflector 1 for reflecting the light that is not condensed by the optical lens 9a and directing it to the photodiode 8.
It has 0 and.

Like the reflector 2 of the transmitter A, the reflector 10 is formed in a substantially disk shape having a recess 10a on one surface, and the recess 10a goes from the opening surface side to the bottom surface 10b side. The opening cross-sectional area is formed to be gradually smaller, and the light emitted from the end surface of the core F1 of the optical fiber F is reflected by the inner surface of the recess 10a. In addition, a groove 10d is further provided in the peripheral portion of the recess 10a of the reflector 10. Further, the reflector 10 is formed with a wiring pattern for electrically connecting to the photodiode 8 and allowing the photodiode 8 to receive light, and the groove portion 10d is provided with a wire bond pad 10c for connecting with the wiring pattern. . The photodiode 8 is arranged in the recess 10a at a substantially central portion of the bottom surface 10b with the light receiving portion 8a facing the opening surface side.

The translucent member 9 is a recess 10 of the reflector 10.
a and the inside of the groove 10d are filled with the photodiode 8
9d for sealing the and the recess 10 in the sealing 9d
It is composed of a peripheral wall 9b protruding from the vicinity of the peripheral edge of the opening a toward the side opposite to the reflector 10 and the above-mentioned condenser lens 9a, and is integrally formed of a translucent resin.

Like the condenser lens 3a of the transmitter A, the condenser lens 9a is a spherical lens and is located on the opposite side of the photodiode 8 of the sealing portion 9d so as to be surrounded by the peripheral wall 9b. The converging lens 9a is not limited to a spherical lens and may be an aspherical lens.

The procedure for manufacturing the receiver B from the photodiode 8, the reflector 10 and the translucent member 9 as described above is the same as that of the transmitter A described above. First, the reflector 10 is molded with a resin material, A wiring pattern is formed by plating the surface of the reflector 10 with copper, nickel, or gold. And the groove 10d
A wire bond pad 10c is provided on.

Next, the photodiode 8 is die-bonded on the bottom surface 10b of the recess 10a with a conductive adhesive,
The electrodes on the surface of the photodiode 8 opposite to the light receiving portion 8a are connected to the wiring pattern formed on the bottom surface 10b. Further, the electrode on the surface of the photodiode 8 on the side of the light receiving portion 8a and the wire bond pad 10c in the groove 10d of the reflector 10 are wire-bonded with the gold wire 21.

Here, both the anode and cathode electrodes of the photodiode 8 are connected to the light receiving portion 8 of the photodiode 8.
When it is on the a-side surface, the photodiode 8 may be bonded to the bottom surface 10b of the recess 10a by using a non-conductive adhesive as well as the conductive adhesive as described above.
Further, in this case, two wire bond pads 10c are provided,
The electrodes are separately connected to the wire bond pads 10c by gold wires 21.

When both electrodes of the photodiode 8 are on the surface opposite to the light receiving portion 8a of the photodiode 8, the photodiode 8 is formed by the flip chip mounting method.
Is mounted on the bottom surface 10b. At this time, both the anode and cathode electrodes of the photodiode 8 are individually connected to the two pad electrodes formed in the wiring pattern on the bottom surface 10b.

Finally, the light-transmissive member 9 is transfer-molded with a light-transmissive resin. At this time, the photodiode 8 is sealed by the sealing portion 9d of the translucent member 9,
d, the plate portion 9c, the peripheral wall 9b, and the condenser lens 9a are integrally molded. As a result, the receiver B is completed.

In the receiver B of this embodiment, an optical connector (not shown) is provided so that the light receiving portion 8a of the photodiode 8 substantially faces the end face of the optical fiber F with the condenser lens 9a interposed therebetween. Connected to the optical fiber F. At this time, the opening surface of the recess 10a of the reflector 10 is oriented toward the end surface of the optical fiber F, and the condenser lens 9a is convex toward the end surface of the optical fiber F. Further, since one end of a ferrule (not shown) that supports the optical fiber F is brought into contact with the peripheral wall 9b of the translucent member 9, the distance between the end face of the optical fiber F and the condenser lens 9a is kept substantially constant, The end face of the optical fiber F is positioned.

When light is emitted from the end face of the core F1 of the optical fiber F at an angle corresponding to NA, the end face of the optical fiber F is positioned near the condenser lens 9a as shown by the solid line in FIG. If so, all the emitted light is collected by the condenser lens 9
of the emitted light by condensing the light on a and directing it toward the light receiving portion 8a of the photodiode 8.
Light directed in a different direction from the light receiving section 8a toward the light receiving section 8a
It is possible to increase the amount of light radiated to the optical fiber and improve the coupling efficiency with which the light from the optical fiber F is coupled to the light receiving portion 8a.

Further, as shown by the two-dot chain line in FIG. 5, even when the end face of the optical fiber F is moved away from the condenser lens 9a, the light emitted from the end face of the optical fiber F is only partially condensed. 9a is no longer condensed, but a condenser lens 9a
The light that is not focused on the concave portion 10a of the reflector 10
By being reflected by the inner surface and directed to the light receiving portion 8a, the coupling efficiency with which the light from the optical fiber F is coupled to the light receiving portion 8a can be improved, as described above.

As a result, the position of the end face of the optical fiber F is displaced, and the distance between the end face and the condenser lens 9a and the photodiode 8 becomes long, so that the coupling efficiency is prevented from being lowered. Therefore, in the receiver B of the present embodiment, the positioning of the end face of the optical fiber F does not require high accuracy, and the receiver B can be easily manufactured. That is, in the present embodiment, as described above, one end of the ferrule supporting the optical fiber F is brought into contact with the peripheral wall 9b of the translucent member 9 to position the end face of the optical fiber F. The peripheral wall 9b may not be brought into contact with the peripheral wall 9b, and the peripheral wall 9b may not be provided on the translucent member 9.

The optical fiber F may be a plastic optical fiber, a silica optical fiber, or a polymer clad fiber. (Embodiment 2) Since the basic configuration of this embodiment is the same as that of the first embodiment, common parts are designated by the same reference numerals and description thereof is omitted, and only the characteristic parts of this embodiment will be described in detail. To do.

The transmitter A and the receiver B of this embodiment are characterized in that a plurality of condenser lenses 3a and 9a are provided as shown in FIGS. 6 and 7, respectively. The plurality of condenser lenses 3a and 9a may be spherical lenses or aspherical lenses. For example, in the receiver B, a condenser lens 9a, which is a spherical lens, is arranged at a substantially central portion of a portion surrounded by the peripheral wall 9b of the sealing portion 9d, and a plurality of spherical lenses that are spherical lenses are provided so as to surround the peripheral portion. 9a may be arranged in a circular shape, or a donut-shaped condensing lens 9a may be arranged so as to surround the circumference of the condensing lens 9a in the substantially central portion.

As a result, the transmitter A of this embodiment is
Then, a larger amount of light from the light emitting diode 1 is collected and directed toward the end face of the core F1 of the optical fiber F, and the end face of the core F1 is N
It is possible to increase the amount of light emitted within the range of the light receiving angle corresponding to A, and further improve the coupling efficiency. Further, in the receiver B of the present embodiment, more light emitted from the end face of the core F1 of the optical fiber F is condensed and directed toward the light receiving portion 8a of the photodiode 8 to increase the amount of light emitted to the light receiving portion 8a. Therefore, the coupling efficiency can be further improved.

[0047]

According to a first aspect of the present invention, there is provided a transmitter for transmitting an optical signal through an optical fiber, which comprises a light emitting element which emits light which becomes the optical signal, and a light which is emitted from the light emitting element. Since a reflector for reflecting at least a part of the light toward the end surface of the optical fiber and a condenser lens for condensing at least a part of the light emitted from the light emitting element on the end surface of the optical fiber are provided, the light emitting element Of the light from the outside of the light receiving angle range according to the numerical aperture of the optical fiber, or the light heading in a direction different from the end face of the optical fiber is reflected by the reflector and condensed by the condenser lens. By directing the light toward the end face, it is possible to increase the amount of light applied to the end face of the optical fiber within the range of the light receiving angle, and improve the coupling efficiency of coupling the light from the light emitting element to the end face of the optical fiber. There is an effect.

According to the invention of claim 2, since a plurality of condenser lenses are provided, more light from the light emitting element can be condensed and directed to the end face of the optical fiber, and the coupling efficiency can be further improved. The effect is that you can do it.

According to a third aspect of the present invention, there is provided a receiver for receiving an optical signal transmitted via an optical fiber, which is at least a light receiving element and light emitted from the end face of the optical fiber as the optical signal. The optical fiber is provided with a condensing lens for condensing a part of the light on the light receiving element, and a reflector for reflecting the light, which is not condensed by the condensing lens, of the light emitted from the end face and directs it toward the light receiving element. At least a part of the light emitted from the end face of the light and directed in a direction different from the light receiving element is condensed by the condenser lens, and the light not condensed by the condenser lens in the light directed in the different direction is reflected by the reflector. By reflecting the light to the light receiving element and directing it toward the light receiving element, it is possible to increase the amount of light irradiated to the light receiving element and improve the coupling efficiency with which the light emitted from the end face of the optical fiber is coupled to the light receiving element. There is an effect that.

According to the invention of claim 4, since a plurality of condenser lenses are provided, more light emitted from the end face of the optical fiber can be condensed and directed to the light receiving element, further improving the coupling efficiency. The effect is that you can.

[Brief description of drawings]

FIG. 1A is a side sectional view of a transmitter, and FIG. 1B is a side sectional view of a receiver according to a first embodiment.

FIG. 2 is a rear view of the transmitter of the above.

FIG. 3 is a side sectional view for explaining the operation of the above transmitter.

FIG. 4 is a rear view of the above receiver.

FIG. 5 is a side sectional view for explaining the operation of the above receiver.

FIG. 6 is a side sectional view of a transmitter according to a second exemplary embodiment.

FIG. 7 is a side sectional view of the above receiver.

[Explanation of symbols]

1 light emitting diode 2 reflector 3a condenser lens 8 photodiodes 9a condenser lens 10 reflector A transmitter B receiver F optical fiber

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Claims (4)

[Claims] 1. A transmitter for transmitting an optical signal through an optical fiber, comprising: a light emitting element that emits light that becomes the optical signal; and a light emitting element that reflects at least a part of the light emitted from the light emitting element. And a condenser lens for condensing at least a part of the light emitted from the light emitting element on the end face of the optical fiber. 2. The transmitter according to claim 1, further comprising a plurality of condenser lenses. 3. A receiver for receiving an optical signal transmitted via an optical fiber, wherein the light receiving element and at least a part of the light emitted from the end face of the optical fiber as the optical signal are received. A condenser lens that collects light on the element,
A receiver comprising: a reflector that reflects, of the light emitted from the end face, light that is not condensed by a condenser lens and directs the reflected light to the light receiving element. 4. The receiver according to claim 3, further comprising a plurality of condenser lenses.