JPS61150533A - Optical wavelength multiplex circuit device for optical fiber communication - Google Patents

Abstract

PURPOSE:To minimize the leakage quantity of a signal, and to improve the transmission quality by covering a light emitting element, photodetector, lens and a filter, respectively, with a light shielding member, except a filter opening part, and inserting individual aperture diaphragm between the light emitting element and the lens and the photodetector and the lens, between the lens and the filter, and into at least one place of the filter opening part. CONSTITUTION:The light whose radiation angle is small, among the lights which is emitted from a light emitting diode 1 is sent out to an optical fiber 5. Among the lights which is emitted from the light emitting diode 1, the light which has a large radiation angle and is not made incident on a lens 32, such as light 71 is brought to light shielding by a light shielding member 81, and attenuated as its multipath reflection is repeated in this member. Also, the light which goes into an opening of the lens 32 but is subjected greatly to an aberration of the lens 32, for instance, such as light 72 is shielded and attenuated by an aperture diaphragm 91 or 92. In such a way, a light radiated into an optical circuit device always becomes only a light whose unnecessary wavelength component is attenuated by a filter 43.

Description

[Detailed Description of the Invention] Industrial Application Field] Cocn The invention relates to an optical wavelength multiplexing circuit device for optical fiber communication, and to be more specific.

Sending multiple optical signals to one optical fiber, and.

The present invention relates to an optical wavelength multiplexing circuit device for optical fiber communication for separating a plurality of optical signals in one optical fiber.

[Conventional technology]

Figure 2 shows 1. For example, the 1985 IEICE General Conference National Conference Proceedings, paper number tco (separate volume lθ, p10
-Jtrut) Conventional optical wavelength multiplexing circuit device 111 for optical fiber communication (hereinafter abbreviated as optical circuit device)
In Figure 1, (/1 is a light emitting diode with a center emission wavelength gZOfl, and (2) is a light receiving element.

(,7/), (,?2), (,?,?) are lenses, ('
I/) Ada 2) is a dielectric multilayer filter that transmits 7tOxl light and reflects light of other wavelengths, ('IJ) is ggO
A dielectric multilayer filter that transmits FII+ light and reflects other light.

(5) is an optical fiber, and (6) is an outer box of this optical circuit device. O With the above configuration, the optical output of one light emitting diode (/l) is converted into a parallel light beam by the lens (32), and the filter (
11,y), and after wavelength components other than ffzaOmyi are removed, the light enters a filter (tar), and the light with a wavelength of ggOmm is reflected by this filter bow).

The light is focused by the lens (33) and sent out to the optical fiber (3). - The light is focused by the waves (31) that have propagated through the optical fiber (S) and enters the light receiving element (2). Using this optical circuit device, a plurality of optical signals can be separated and combined into one.

On the other hand, in such a device, it is necessary to prevent the optical signal from one light emitting diode (/1) from becoming noise to the optical signal with a wavelength of 710 yen which is incident on the five light receiving elements (2). In the device, even if an optical signal from a light emitting diode (1) is reflected at the end face of a lens (,?,,?)'P optical fiber (5), travels backwards, and enters a filter (G2), , the light emitting diode f/) is reflected by this filter (ll) and does not reach the light receiving element (λ).
The emission wavelength spectrum of is wide <,, even in the light emitting diode (1) with the center wavelength at ggOm.

There is light with a wavelength component of 710 m, but since this wavelength component has already been removed by the filter (q3), it does not reach the light receiving element (2) through the above-mentioned path.

However, in general, the light emitted from a single light emitting diode (/l) has extremely poor directivity.

It has a light component with a large emission angle. Therefore, some of the light emitted from the light emitting diode (/l) is
), the light is emitted outside the aperture of the lens (32),
As shown by the dashed line (7, 2), even if the light is emitted within the aperture of the lens (32), it passes through the edge of the lens (J2), so it is greatly affected by the aberration of the lens, and in both cases it is incident on the filter (ay). The angle will deviate significantly from the predetermined angle, and the filter will not function normally. These lights are real! (?
It deviates from the normal optical path shown in j), is emitted into the optical circuit device, and undergoes multiple reflections on the side walls of the lens and filter and the inner wall of the outer box (6). A part of the light is directly incident on the light receiving element (2), for example, as shown by a dashed line (73). Also, some light enters the filter (at) as shown by the dashed line (7 da), but this light is not filtered by the filter (da 3) as described above, so the 7g000 wavelength component This component of light passes through the filter (aJ), passes through the lens (31), and enters the light receiving element (2). All of these lights (leakage lights) entering the light receiving element (, 2) are connected to the optical fiber (,!i)
The transmission quality deteriorates because it becomes noise to the optical signal of wavelength 7 Ofl that has been propagated.

In fact, even if such leakage light occurs at an extremely small rate, it has a significant impact on transmission quality. For example, consider the case where bidirectional wavelength multiplexing transmission is performed using this conventional optical circuit. The optical signal propagated through the optical fiber Lt) from a distance is extremely weak, and 1 normal = jO~-A Od
It is considered to be the optical power of Bm. On the other hand, light emitting diode (1)
The optical output of is about OdBm. Measures the amount of light leaked from optical signals from a distance.

A! for the output of the direct diode (1) which is generally required for digital signal transmission! ;dB and 7jdB, that is, it is necessary to suppress it to less than 1/1 million to 1/10,000,000. In conventional optical circuit devices that do not have sufficient measures against leakage light, it is extremely difficult to reduce the leakage light to such an extremely small level.

[Problem to be Solved by the Invention 1] The conventional optical circuit device as described above has the problem of deterioration of transmission quality due to leakage light entering the light receiving element.

This invention was made in order to solve this problem, and is applicable to devices using light (m < It is an object of the present invention to obtain a wavelength division multiplexing circuit device for optical fiber communication which has excellent transmission quality by suppressing leakage light to a sufficiently small level. This optical wavelength multiplexing circuit device for optical fiber communication has six light-emitting elements, a light-receiving element, a lens, and a filter, each of which is covered with a light-shielding member except for the filter opening, and between the light-emitting element, the light-receiving element, and the lens, and between the lens and the filter. , filter openings are small (both have an aperture diaphragm inserted in one location).

[For production]

In this invention, by the function of the light shielding member.

Of the light emitted from the light emitting element, the light emitted outside the lens aperture and filter aperture is attenuated without being emitted into the optical circuit device. Furthermore, light that enters the lens aperture but is greatly affected by lens aberration is attenuated by the aperture stop without being emitted into the optical circuit device. On the other hand, light that does not pass through the normal beam and enters the light receiving element is blocked by the light shielding member and the aperture stop.

〔Example〕

FIG. 1 shows an embodiment of the present invention, indicated by reference numeral (1).

f2), (tt>, (32), (, yJ), (da l),
(Hiroshi 2), (G 3).

(jl and fil are exactly the same parts as in Fig. 2. (gt) is ``0 element (/1.1/
,? 2), the filter p (a, 7) is the light shielding member, (9/), (9λ) is the emitting element (/l and the lens (32) lined up at 1 and the filter (q3) aperture , (g,
2) is a light-shielding member that covers the light-receiving element (2), lens (,7/'), and filter cμ2) without any gaps; (93), (
9D) is an aperture stop inserted into the light receiving element (2), lens (31), and filter (4tt) apertures.

With the above configuration, among the light emitted from one light emitting diode f/l, the light with a radiation angle of -J- is sent out to the optical fiber (jl) by the same operation as described above. The light of different wavelengths also reaches the light receiving element (2) in exactly the same way as described above.

Here, out of the light emitted from the two light emitting diodes (/l), the light that has a large radiation angle and does not enter the lens (31), such as the ray (7/), is blocked by the light shielding member (ri), and multiple reflections occur within it. Attenuates as it is repeated.

In addition, 1. For example, light rays such as light fa (72) that enter the aperture of the lens (32) but are subject to large aberrations of the lens (3λ) are blocked and attenuated by the aperture stop [9/) or (?2). . In this way, the light emitted into the optical circuit device is always only light with unnecessary wavelength components attenuated by the filter (41y).

Note that the light with a large radiation angle described here is light that is not coupled to the optical fiber (3) even if it is not blocked by the light blocking member (Z1) or the aperture stop (qi) Aq2), so the light with a large radiation angle is It is clear that the provision of (gt), -aperture diaphragm (qt), and (q2) does not reduce the efficiency of this optical circuit device.

Now, a part of the light emitted from the opening of the filter (3) is scattered by the lens (JJ) and the end of the optical fiber (3). Among these types of light, for example, there is light that attempts to directly enter the light receiving element (λ) without passing through the filter (III'), such as the light ray (RI3), and light that attempts to directly enter the light receiving element (λ) without passing through the filter (III'). '
/) K The light that does not enter the predetermined voice change and is therefore subjected to a normal filtering action, but passes through the filter due to no liquid, is transmitted through the light shielding member (t2) and the aperture diaphragm (q, y).

(9 da)K, it is attenuated before entering the light receiving element (,21K).As a result, in this optical circuit device, it is possible to minimize the amount of light leaking from the light emitting diode t73 to the light receiving element (2). can.

In one or more of the embodiments, a case has been described in which a light emitting element and a diode are suddenly used as one light emitting element, but the same applies to the case where a semiconductor laser is used as a light emitting element.

〔Effect of the invention〕

The invention will be apparent from one or more of the descriptions.

A light shielding member blocks light that does not pass through the filter section.

In addition, the aperture diaphragm is used to ensure that the light that passes through the filter but does not receive the normal filtering action because it deviates from the predetermined incident angle is attenuated, minimizing the amount of leakage and improving transmission quality. can.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of an embodiment of the present invention, and FIG. 2 is a side sectional view of a conventional optical wavelength multiplexing circuit device for optical fiber communication. (1)...Light emitting diode (light emitting element), (2)...Light receiving electron, (32), (,7/)...First and second lenses. (4LJ) + (Gl)...first and second filters, (S). Optical fiber, (t i ) + (t 2 )...first lλ light shielding member, (qi'>, ('y2)...first
aperture stop, (9,y). (Deda)...Second aperture diaphragm. In each figure, the same reference numerals indicate the same or corresponding parts. Outer 1 figure 1: Selling 9+ 2: Seated koto+ 32.31: 71. ↑2 Noshishi X43.41
: 71. Sai 2 refill j Shiri 5: Hikari 7 fill ■

Claims (2)

[Claims] (1) an optical fiber, and a light emitting element that is provided with a first lens and a filter and sends an optical signal to the optical fiber;
In an optical wavelength division multiplexing circuit device for optical fiber communication, comprising a second lens and a light receiving element that is provided with a filter and receives an optical signal from the optical fiber, the first lens, the filter, and the light emitting element are opened. A first light-shielding member that covers the light-shielding member without any gaps except for the opening, and a second light-shielding member that covers the second lens, the filter, and the light-receiving element without any gaps except for the opening.
1. An optical wavelength division multiplexing circuit device for optical fiber communication, comprising: a light shielding member; and at least one aperture diaphragm disposed on each of the first and second light shielding members. (2) A first aperture diaphragm disposed at at least one location between the light emitting element and the lens, between the lens and the filter, and at the filter opening, and at least one location between the light receiving element and the lens, between the lens and the filter, and at least one location at the filter opening. The second
An optical wavelength division multiplexing circuit device for optical fiber communication according to claim 1, comprising an aperture diaphragm.