JPS6074587A - Light-emitting semiconductor device with monitor output - Google Patents

Abstract

PURPOSE:To obtain a light-emitting output monitor signal of a large output, and to form the titled device in simple structure by efficiently combining an optical output from a semiconductor light-emitting element with an optical fiber for transmission while combining the greater part of optical power not combined with the optical fiber with another optical fiber group. CONSTITUTION:A glass tube 12 in which optical fibers 15 for leading out monitor beams are positioned concentrically around an optical fiber 13 centering around the optical fiber 13 is inserted into a package, and arranged oppositely to the light-emitting surface of a semiconductor light-emitting element 1. The optical fiber 13 for transmission and optical fiber groups 14 for leading out monitor beams are separated from the other end of the glass tube, and the other ends of the optical fiber groups for leading out monitor beams are disposed oppositely to a light-receiving element 10. For lead out optical power not combined with the optical fiber 13 for transmission to the optical fibers 15 for leading out monitor beams as much as possible, the outer diameter of the optical fibers 15 is reduced, the number of the optical fibers 15 is increased, and a difference between the refractive indices of a core and a clad is augmented (1% or higher), and it is preferable that the thickness of the clad is thinned (several mum-several dozen mum).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a light emitting semiconductor device with a monitor output, which is provided with means for monitoring part of the light output from a semiconductor light emitting element such as a light emitting diode or a semiconductor laser.

[Background of the invention]

Light-emitting diodes and semiconductor lasers are used as light-emitting devices for optical fiber communications, but the light output of these light-emitting devices tends to fluctuate due to temperature fluctuations, drive power fluctuations, etc., so it is difficult to stabilize the light output. ization is considered essential. In order to stabilize this light output, a part of the light output is derived and detected by a light receiving element and monitored, or the monitor signal is fed back to the drive circuit of the light emitting element to control the drive current and output light. is being stabilized. As a means of monitoring this light output,
Conventionally, methods as shown in FIGS. 1 and 2 are known. FIG. 1 shows that out of the light emitted by a semiconductor light emitting device 1, the light that has entered the acceptance angle of an optical fiber 5 is transmitted through the optical fiber 5, and a part of the light output is transmitted via a lens element 7 to a beam splitter 9. This is a method in which the light is branched, photoelectrically converted by the light receiving element 10, and monitored. However, this method had the following drawbacks.

(1) When the semiconductor light emitting element is a light emitting diode, the power coupled into the optical fiber 5 is small (about several tens of microwatts), so transmission is limited to short distances, and a beam splitter 9 is further inserted for monitoring. The more light is emitted, the shorter the transmission distance becomes.

(2) Since there are also aberration losses in the lens elements 7 and 8 and branching losses in the beam splitter 9, the optical power transmitted through the optical fiber 6 is further reduced.

(3) It is difficult to adjust the optical axis V of the optical system (5 to 10),
Moreover, it is difficult to miniaturize the device.

FIG. 2 is one way to solve the drawbacks of FIG. 1. This is a composite semiconductor device in which a photoelectric conversion device such as a semiconductor light receiving device 10 prepared in advance at the bottom of a package 2 is integrated. One method of optical monitoring of this device is to reflect the light that is not coupled to the optical fiber 5 out of the optical output of the semiconductor light emitting device 1 on the inner wall surface of the package and send it to the light receiving device 10.
It was designed so that light could be focused on the area. This method is the first in that it does not cause any loss in the optical power that has been coupled into the optical fiber 5 and allows the optical output to be monitored.
This method is more advantageous than the method shown in the figure. However, with such a structure, it is extremely difficult to condense all the optical power of the semiconductor light emitting element that has not been coupled to the optical nozzle 1 eyer 5 onto the light receiving element 10, and the optical power for monitoring is weak. . Therefore, such weak light is unstable and insufficient as a light emission output monitor signal. Furthermore, when used as a control signal for a drive circuit for a semiconductor light emitting device, the weak light mentioned above requires a large gain in the feedback amplifier circuit, which forces a narrowband feedback loop system, making wideband signal transmission difficult. There were some problems. In addition, in FIG. 1.2, 3.4 is an electrode pin that supplies input current to the semiconductor light emitting device 1.

[Purpose of the invention]

It is an object of the present invention to efficiently couple optical output from a semiconductor light emitting device such as a light emitting diode or a semiconductor laser to a transmission optical fiber, and to transfer almost all of the optical power not coupled to the optical fiber to another optical fiber. It is an object of the present invention to provide a light-emitting semiconductor device with a monitor output, which is coupled in groups and inputted to a light-receiving element to obtain a large-output light-emission output monitor signal or a control signal for a drive circuit for the semiconductor light-emitting element.

[Summary of the invention]

In the present invention, a transmission optical fiber is arranged at the center axis in a dielectric tube (glass tube, plastic tube, magnetic tube, ceramic tube, etc.), and a single or multiple monitor light is connected concentrically around the optical fiber. one end of the dielectric tube in which the fiber group is arranged is opposed to the light emitting surface of the semiconductor light emitting device;
This is a light emitting semiconductor device with a monitor output, in which the other ends of a group of optical fibers for leading out monitor light are assembled and coupled to a light receiving element. The light spread from the light emitting surface of the semiconductor light emitting device is 9
By arranging the monitor light output fibers in multiple concentric circles to compensate for the area, almost all of the optical power that is not coupled to the transmission optical fiber can be transferred to the monitor light output optical fiber i5). I can guide you to. The structure of the optical fiber for guiding the monitor light may be the same as that of the optical fiber for transmission, but in order to guide more optical power, it is necessary to use a smaller shape and increase the refractive index of the core and cladding of the optical fiber. The larger the difference, the better.

In addition, by adjusting the distance between the dielectric tube and the semiconductor light emitting element, the inclination, etc. so that the optical power at the output end of each optical fiber for leading out the monitor light is equal, the light to the transmission optical fiber can be adjusted. The coupling efficiency can be maximized. Furthermore, in the conventional method, even if the optical fiber 5 is inserted into the package and fixed after adjusting the optical axis, the optical axis is easily misaligned because the optical fiber has a small diameter and is somewhat flexible, and the fixing method is also difficult. In the configuration of the present invention, the dielectric tube has a large diameter and is hard, so it is easy to fix, and it also has the characteristics that it is difficult to shift even after adjusting the optical axis.

[Embodiments of the invention]

FIG. 3 shows a schematic diagram of a light emitting semiconductor device with a monitor output according to the present invention. In this figure, the same reference numerals as in FIG. 1.2 are the same.

(6) 12 is a transmission optical fiber 13. This is a glass tube into which a group of optical fibers 14 for leading out monitor light are inserted and filled, and is inserted into the package 2 and placed opposite the light emitting surface of the semiconductor light emitting element 10. The transmission optical fiber 13 and the monitor light guide optical fiber group 14 are separated from the other end of the glass tube.

The other end of the optical fiber group for guiding the monitor light is arranged to face the light receiving element 10.

FIGS. 4 and 5 show an embodiment of the transmission optical signal and monitoring optical signal deriving section of the present invention. (a) is an overview map% (b
) is a left side view, and (C) is a right side view. glass tube 12
The arrangement of the respective fibers is such that the optical fiber 13 is placed on the central axis of the glass tube, and the optical fiber 15 for guiding the monitor light is placed concentrically around the optical fiber 13. The number of optical fibers 15 for guiding the monitor light is 8 in the case of FIG.
In the case of Fig. 5, there are six. The fixation of each fiber is maintained by filling the gap between the optical fibers with resin 16 (or adhesive may be used).

In the case of FIG. 4, the outer diameter of the monitor light guiding optical fiber 15 is smaller than that of the transmission optical fiber 13;
The same is true for figures. Monitor the optical power that is not coupled to the transmission optical fiber 13 Optical fiber 1 for deriving light
5, the outer diameter of the optical fiber 15 should be small, the quantity should be large, the difference in refractive index between the core and the cladding should be large (1% or more), and the thickness of the cladding should be small (1% or more). (several μm to 10-odd μm) is good for gargling.

The left end surface of the glass tube (the surface facing the light emitting surface of the semiconductor light emitting element) is polished. The end face of the optical fiber group 14 ((C
) side) may be formed into a ring shape as shown in FIG. 4, an array shape as shown in FIG. 5, or a bent state in order to improve coupling with the light receiving element.

Reference numeral 17 denotes a cladding tube for the optical fiber group 14, which is made of a 9% glass tube or a polymer material tube. The optical fiber 13 for guiding the monitor light is arranged so that the inner diameter of the glass tube 12 is such that the light spread from the light emitting surface of the semiconductor light emitting element is equal to or larger than 9 areas. In all of the above embodiments, the optical fibers are arranged in a single concentric circle, but if the optical fibers are arranged in multiple concentric circles such as double or triple, it is possible to obtain a higher output light emission output monitor signal. Therefore, it is preferable that the number of optical fibers 13 for leading out the monitor light be as large as possible. Furthermore, in the configuration of the present invention, the glass tube is thick and hard, so it is easy to insert and fix into the package, and even after the p1 optical axis is adjusted, the p optical axis is unlikely to shift due to vibration or the like.

Further, the optical axis can be adjusted while observing so that the output power of each optical fiber 15 is equalized. Furthermore, the transmission optical signal and the monitoring optical signal derivation section are integrated and one-to-one.
There is a simple relationship between On the other hand, in the conventional method, the optical fiber 5 has a small diameter and is too flexible, so there is a problem in that the optical axis is easily misaligned due to vibration or the like. It is obvious that the apparatus of the present invention can be similarly applied even when the semiconductor light emitting element has an optical output characteristic of an elliptical radiation pattern, such as a semiconductor laser.

6 and 7 show another embodiment of the transmission optical signal and monitoring optical signal deriving section of the present invention.

This is made by inserting various optical fibers and processing the tip of the filled glass (9) tube 12 into a spherical lens as shown in 18.19. This improves the efficiency of light coupling into the optical fiber. It is possible to reduce the amount of light reflected from the end face of the optical fiber returning to the semiconductor light emitting device. This process can be performed by heating the tip of the glass tube with an oxyhydrogen burner to utilize surface tension. Alternatively, it can also be achieved by attaching a hemispherical microlens 9 to the end face of a flat glass tube as shown in FIG. 4.5.

Compared to the conventional tip processing of a single optical fiber, such tip processing is easier to process and manufacture because the shape is thicker, and the yield is higher. Furthermore, it is possible to easily make spherical lenses with different spherical shapes having a focal length of 1. Due to the large spherical shape, the efficiency of coupling light into the optical fiber can be significantly increased compared to conventional methods.

In addition to glass tubes, dielectric tubes include tubes made of polymeric materials (for example, Teflon tubes, silicone rubber tubes, polypropylene tubes, nylon tubes, or heat-shrinkable tubes made of silicone, fluororesin, etc.); A tube made of a magnetic material such as ceramics can be used.In order to fix the package 2 and the glass tube 12, a metal film can be formed on the entire or partial outer surface of the glass tube by vapor deposition, plating, etc. However, it may be soldered to package 2.

Optical fibers can be multimode fibers, single mode fibers, etc. Particularly when using a single mode fiber, in order to further increase the optical coupling efficiency, the tip of the glass tube 12 should be
Make it tapered as shown. In order to further increase the optical coupling efficiency, the tip is processed into a spherical lens 21 as shown in FIG. 6.7. In the case of a single conventional optical fiber, the core diameter is as small as several μm to 10-odd μm, and the cladding diameter is as small as 125 μm, making it extremely difficult to process.However, in the case of the present invention, the glass tube outer diameter is 0.5 μm. 4
It is extremely easy to process, ranging from ttan to several digits.

〔Effect of the invention〕

(11) According to the present invention, the optical output from the semiconductor light emitting device is efficiently and stably coupled to the transmission optical 7-iper, and
Almost all of the optical power that is not coupled to the optical fiber can be coupled by the monitor light guide optical fiber group and input to the light receiving element. Therefore, it is possible to obtain a high-output light emission output monitor signal, which can be effectively used as a control signal for the drive circuit of the semiconductor light emitting device, and to reduce the gain of the amplifier circuit in the feedback loop system to improve broadband characteristics. This makes it possible to transmit broadband signals. Furthermore, since the derivation parts for the transmission optical signal and the monitoring optical signal are integrated and have a one-to-one relationship, it is possible to adjust the optical axis while observing the monitoring optical signal output, which is extremely effective compared to conventional systems. Simple structure and high reliability.

[Brief explanation of the drawing]

Fig. 1.2 is a schematic diagram of a conventional light emitting semiconductor device with a monitor output, Fig. 3 is a schematic diagram of a light emitting semiconductor device with a monitor output of the present invention, and Figs. Embodiment (12) of the optical signal deriving section is shown. 1... Semiconductor light emitting device, 2... Package, 3, 4
... Electrode pin% 5.6 ... Hikari 7 Aiba, '7, 8.
11... Lens element, 9... Beam splitter, 1
0... Light receiving element, 12... Glass tube, 13... Optical fiber for transmission, 14... Group of optical fibers for leading out monitor light, 15 Optical fiber for leading out monitor light, 16...
Resin, 17... Covering tube, 18, 19. 21... Spherical lens processing part, (13) Fig. 1'WJ3t\] Fig. 6! A Figure 7 Figure δ Figure 9 Factor

Claims (1)

[Scope of Claims] 1. One end of the dielectric tube, comprising a transmission optical fiber disposed at the central axis of the dielectric tube, and a group of seven eyepers for guiding light for monitoring arranged concentrically around the optical fiber in single or multiple configurations. A half-
A light-emitting semiconductor device with a monitor output, which is arranged to face a light-emitting surface of a conductive light-emitting element, and the other end of the group of optical fibers for leading out monitor light is assembled and coupled to a light-receiving element. 2. In the light emitting semiconductor device with a monitor output according to item 1, the end face of the dielectric tube facing the light emitting surface of the semiconductor light emitting element is stretched into a tapered shape or a spherical lens is formed. A light-emitting semiconductor device with a monitor output as described in 2.