JPH02130507A - Photodetecting element component - Google Patents

Abstract

PURPOSE:To prevent reflected feedback light to a transmission side from being generated and to easily confirm a position shift perpendicular to an optical axis by slanting a photodetection surface to the plane perpendicular to the optical axis of converged light beam flux by a lens and equalizing the divergence of reflected light beam flux on the photodetection surface of a subordinate photodetecting element chip to that in the photodetection area of the subordinate photodetecting element chip. CONSTITUTION:The photodetection surface 2a of the photodetecting element chip is slanted to the plane perpendicular to the optical axis 4 of the converged light beam flux 3 by the lens 1. Further, the subordinate photodetecting element chip 7 is provided on the optical axis 6 of reflected light beam flux 5 on the photodetection surface 2a and the divergence of the reflected light beam flux 5 on the photodetection surface 7a of the subordinate photodetecting element chip 7 is nearly equal to that in the photodetection area of the subordinate photodetecting element chip 7. Consequently, the reflected feedback light to the transmission side is eliminated and the position shift perpendicular to the optical axis is easily confirmed.

Description

[Detailed Description of the Invention] Overview Regarding the light-receiving element components used to convert optical signals into electrical signals, there is no risk of reflected feedback light to the transmitting side, and positional deviation in the direction perpendicular to the optical axis is avoided. The purpose of providing a light-receiving element component that can be easily confirmed is a light-receiving element component in which the light to be received is focused by a lens and incident on the light-receiving surface of a light-receiving element chip. tilted with respect to a plane perpendicular to the optical axis of the focused ray bundle,
A sub light receiving element chip is provided on the optical axis of the reflected light beam on the light receiving surface, so that the spread of the reflected light beam on the light receiving surface of the sub light receiving element chip almost coincides with the light receiving area of the sub light receiving element chip. and configure it.

INDUSTRIAL APPLICATION FIELD The present invention relates to a light receiving element component used for converting an optical signal into an electrical signal.

In a typical optical transmission system, on the transmitting side, a light emitting element such as a semiconductor laser emits light to send signal light to an optical transmission line (optical fiber), and on the receiving side, the signal light transmitted through the optical transmission line is sent to a light receiving element. The information is reproduced through optical-to-electrical conversion. The light-receiving surface of the light-receiving element does not absorb all of the incident light energy, but some of it is reflected back to the transmitting side, which may have a negative effect on the driving of the light-emitting element, so reflected feedback light is not generated. There is a demand for six light-receiving elements with such a structure. Furthermore, in devices such as light-receiving modules constructed using light-receiving element components, it is desired that high light-receiving efficiency can be maintained stably for a long period of time.

Conventional technology FIG. 6 is a sectional view of a conventional general light receiving element component.

This light-receiving element component 10 includes a chip mount 14 on which a light-receiving element chip 12 is placed and fixed, a pedestal 20 on which the chip mount 14 and electrode terminals 16 and 18 for signal extraction are fixed, and a pedestal 20 on which the light-receiving element chip 12 is mounted and fixed. It is composed of a cap 22 that hermetically seals the side, and the cap 22
A transparent window 24 is attached to the portion through which the light-receiving optical axis passes through. Light emitted from the output end of an optical fiber (not shown), or light emitted from the output end of the optical fiber that is collimated by another lens (not shown), is focused by the lens 26 and incident on the light receiving surface of the light receiving element chip 12. It has become. The reason why the received light is focused by the lens in this way is to increase the light receiving efficiency.Also, as shown in Figure 7, the light receiving spot is made sufficiently small compared to the light receiving area of the light receiving surface. This is to prevent the light receiving efficiency from decreasing due to mechanical fluctuations.

Problems to be Solved by the Invention In the structure of conventional light-receiving element components, the light-receiving surface of the light-receiving element chip is arranged perpendicular to the incident optical axis.
The incident optical axis and the reflected optical axis of the light-receiving surface coincide, and the reflected light is introduced into the optical fiber again. When such reflected feedback light occurs in the optical transmission path, the laser oscillation state may be affected and the transmission quality may deteriorate, especially when the transmitting side light source is a semiconductor laser.

Therefore, an object of the present invention is to provide a light-receiving element component that is free from the possibility of reflected light returning to the transmitting side.

Also, in the conventional configuration, by using a lens,
Since the beam system at the light receiving surface is made smaller than the light receiving system, in principle it is possible to obtain high light receiving efficiency, but if the optical axis is misaligned due to external mechanical shock, etc. In other words, if the relative positional relationship between the irradiation beam and the light-receiving surface changes over time or suddenly, there is a problem in that it is impossible to confirm this change. For example, if the light receiving beam that was at the center of the light receiving surface at the time of manufacture moves to the edge of the light receiving surface due to mechanical fluctuations, no change in light receiving efficiency will be observed, but reliability will be affected by new mechanical fluctuations, etc. decreases significantly.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a light-receiving element component that allows easy confirmation of positional deviation in a direction perpendicular to the optical axis.

Means to solve problems FIG. 1 is a diagram showing the principle of the present invention.

1 is a lens that focuses the light to be received, 2 is a light receiving element chip, 2a is its light receiving surface, and the light receiving surface 2a is the lens 1
is inclined with respect to a plane perpendicular to the optical axis 4 of the focused beam 3.

A sub light receiving element chip 7 is provided on the optical axis 6 of the reflected light beam 5 on the light receiving surface 2a, and the spread of the reflected light beam 5 on the light receiving surface 7a of the sub light receiving element chip 7 is It is arranged to almost coincide with the light receiving area No. 7.

According to the configuration of the present invention, the light-receiving surface of the light-receiving element chip is inclined with respect to a plane perpendicular to the optical axis of the beam of light focused by the lens, so that the optical axis of the beam of light reflected on the light-receiving surface is aligned with the above-mentioned direction. The focused ray bundle, ie the optical axis of the incident ray bundle, does not coincide with the optical axis (therefore, reflected return light can be suppressed or prevented).

In addition, a sub-light receiving element chip is provided on the optical axis of the reflected light beam, and the spread of the irradiation beam on the light receiving surface of this sub-light receiving element chip is made to almost match the light receiving area of the sub-light receiving element chip. By detecting fluctuations in the level of light received by the light receiving element chip, it is possible to confirm slight optical axis deviations caused by mechanical shock, deformation over time, and the like.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a sectional view of a light receiving element component showing an embodiment of the present invention. A chip mount 32 is fixed to the base 38 and is made of ceramics, for example. A 7-shaped groove is formed in the upper part of the chip mount 32.
A light receiving element chip 34 such as a photodiode is fixed to one wall surface 32a of the groove. Further, a sub light receiving element chip 36 having a smaller light receiving diameter than the light receiving diameter of the light receiving element chip 34 is fixed to the other wall surface 32b of the 7-shaped groove. Reference numerals 40 and 42 designate electrode terminals protruding downward from the base 38, and these are electrically connected to the sub-light receiving element chip 36. 44 and 46 are electrode terminals that similarly protrude downward from the pedestal 38, and these are electrically connected to the light receiving element chip 34. 48 is a case for hermetically sealing the light receiving element chip 34 and the sub light receiving element chip 36, and this case 48 is attached to the base 3 by, for example, butt welding.
It is fixed to the edge of 8. Reference numeral 50 denotes a transparent window provided in a portion of the case 48 through which the light-receiving optical axis passes, and is made of, for example, sapphire.

FIG. 3 is a sectional view of a light receiving module constructed using the light receiving element component 30 shown in FIG.

The lens 52 is fixed to a lens holder 54, for example, in the correct size, and the lens holder 54 is fixed inside a housing 56. An insertion hole 56a is formed in the housing 56, and optical coupling is achieved by fitting a ferrule of a plug-side optical connector (not shown) into the insertion hole 56a. The light receiving element component 30 is mounted on the pedestal 38 with its case 48 in contact with the lens holder 54.
It is fixed inside the housing 56 by tightening with a screw member 58 from the side. Reference numeral 56b denotes a hole penetrating the side surface of the housing 56, through which the position of the light receiving element component 30 can be adjusted in a plane perpendicular to the optical axis. That is, by loosening the screw member 58 to the extent that the light receiving element part 30 can slide with respect to the screw member 58 and the lens holder 54, and using the tip of a round bottle, etc., the light receiving element part 30 is removed from the outside of the housing 56. The position can be adjusted.

FIG. 4 is an enlarged side view of the chip mount portion in FIG. 2. The light focused by the lens is converted into electricity by the light-receiving element chip 34, and then the light-receiving element chip 34
Each member is arranged so that the reflected light reflected on the light-receiving surface of the sub-light receiving element chip 36 is photo-electrically converted. The focal position and the like are adjusted so that the beam diameter of the light incident on the light receiving surface of the sub light receiving element chip 36 substantially matches the light receiving diameter of the sub light receiving element chip 36. Furthermore, Figure 4 and Figure 1
In the figure, the focal point is shown to be located on the downstream side of the light-receiving surface of the light-receiving element chip in the light propagation direction, but it may be located on the upstream side.

By arranging the light-receiving element chip 34 as shown in FIG. 4, the light-receiving surface of the light-receiving element chip 34 is inclined at an appropriate angle with respect to the plane perpendicular to the axis of light incident on the light-receiving element chip 34, so that light is not received. There is no possibility that the reflected light from the surface will be introduced into the optical transmission path again. In this case, if the angle of inclination is too large, the light receiving sensitivity of the light receiving element chip 34 will decrease, and if the angle of inclination is too small, there is a risk that a part of the reflected feedback light will be reintroduced into the optical transmission path. It is desirable to set the inclination angle by taking these into consideration.

FIG. 5 shows the light receiving element chip 34 and the sub light receiving element chip 3.
6 is a graph showing the change in photocurrent when the photocurrent outputted from 6 is measured and the photodetector component 30 is moved in an arbitrary direction in a plane perpendicular to the optical axis in the configuration shown in FIG. It is.

The graph indicated by A corresponds to the light receiving element chip 34, and the graph indicated by B corresponds to the sub light receiving element chip 36. Since a constant photocurrent is measured in a relatively wide range for the light receiving element chip 34, it is not possible to confirm the positional shift of the light receiving element component 30 from the photocurrent value. On the other hand, for the sub-photodetector chip 36, since the incident beam is made to be almost the same as the light-receiving area, there is almost no part where the photocurrent is constant, and therefore, the change in the measured value of the photocurrent Misalignment of the light-receiving element components can be confirmed.

Also, the light that is just being received when the maximum photocurrent is obtained in the sub-light receiving element chip 36 is the light receiving element chip 34.
If you make sure that the light is illuminated at the center of the light-receiving surface of the
The optical axis can be adjusted when assembling the module so that the photocurrent of the sub-light receiving element chip 36 is maximized. Furthermore, when optical axis misalignment occurs due to mechanical fluctuations or the like during use of the module, the optical axis can be easily adjusted again.

Effects of the Invention As detailed above, according to the light receiving element component of the present invention,
It is possible to prevent reflected feedback light to the transmitting side, and it is also possible to easily confirm positional deviation in the direction perpendicular to the optical axis.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a sectional view of a light-receiving element component showing an embodiment of the present invention, and Fig. 3 is a light-receiving module constructed using the light-receiving element part shown in Fig. 2. 4 is an enlarged side view of the chip mount part of the light receiving element component shown in FIG. 2, FIG. 5 is a graph showing the relationship between photocurrent and movement amount, and FIGS. 6 and 7 are conventional techniques. FIG. 1.52... Lens, 2.34... Light receiving element chip, 7.36... Sub light receiving element chip.

Claims (1)

[Scope of Claims] A light-receiving element component in which light to be received is focused by a lens (1) and incident on a light-receiving surface (2a) of a light-receiving element chip (2), wherein the light-receiving surface (2a) is It is tilted with respect to a plane perpendicular to the optical axis (4) of the bundle of rays (3) focused by the lens (1), and a secondary beam is placed on the optical axis (6) of the bundle of rays (5) reflected by the light receiving surface (2a). A light-receiving element chip (7) is provided, and the spread of the reflected light beam (5) on the light-receiving surface (7a) of the sub-light-receiving element chip (7)
7) A light-receiving element component, characterized in that the light-receiving area substantially coincides with the light-receiving area of item 7).