JPH0645635A - Photodetector - Google Patents

Abstract

PURPOSE:To achieve that a plurality of optical signals transmitted by one optical fiber can be taken out in a branched state by a method wherein a plurality of photodetection faces are formed on one element and wavelength filters are formed on one or more photodetection faces out of the plurality of photodetection faces. CONSTITUTION:A photodetector used for optical communication or the like is provided with two photodetection faces 5, 6 on an element main body 4 via a groove 18. A wavelength filter 7 whose reflection is high with reference to a wavelength lambda1 and whose reflection is low with reference to a wavelength lambda2, i.e., a wavelength filter 7 which selectively takes into only an optical signal at the wavelength lambda1, is formed on the side of the photodetection face 5 by using a dielectric multilayer film or the like. On the other hand, a wavelength filter 8 whose reflection is low with reference to the wavelength lambda1 and whose reflection is high with reference to the wavelength lambda2, i.e., a wavelength filter 8 which selectively takes into only an optical signal at the wavelength lambda2, is formed on the side of the photodetection face 6 by using a dielectric multilayer film or the like. Respective electrodes 9 are installed around the respective wavelength filters 7, 8 so as to be conductive to the corresponding photodetection faces 5, 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light receiving element used for optical communication and the like.

[0002]

2. Description of the Related Art As one system form of optical communication,
There is a system for communicating two signals having different wavelengths using a book optical fiber. In this type of communication system,
For example, as shown in FIG. 4, using one optical fiber 1, an optical signal having a wavelength λ ₁ of 1.3 μm and a wavelength λ ₂ of 1.55 μm are used.
When the optical signal of m is sent, the wavelengths of λ ₁ and λ ₂ are branched using the optical branching (diffraction grating) component 2, and the branched signal of the wavelength of λ ₁ is transmitted through the optical fiber 1a. The photo diode 3a of the light receiving element receives the light, and the signal of the wavelength λ ₂ is received by the photo diode 3b via the optical fiber 1b.

[0003]

However, this type of system requires an optical branching component 2 for branching signals of wavelengths λ ₁ and λ ₂ sent by one optical fiber 1, and further, , Two optical fibers 1a and 1b for individually passing the branched optical signals of λ ₁ and λ ₂ , and each optical fiber 1
There is a problem that a large number of parts are required, such as the need for two photodiodes 3a and 3b for individually receiving the signals a and 1b, and the system of the light receiving portion is complicated and the cost is high.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to simplify the system configuration of the light receiving portion and reduce the number of parts, and accordingly reduce the system construction cost. An object of the present invention is to provide a light receiving element that can be realized.

[0005]

In order to achieve the above object, the present invention is constructed as follows. That is, the light receiving element of the present invention is characterized in that one element is provided with a plurality of light receiving surfaces, and a wavelength filter is formed on one or more of the plurality of light receiving surfaces. ing.

[0006]

In the present invention having the above-mentioned structure, when optical signals of wavelengths λ ₁ and λ ₂ are transmitted using one optical fiber, the optical signal is, for example, two elements of one element. Is incident on the light receiving surface of. At this time, one light receiving surface has a wavelength λ ₁
If a wavelength filter that passes light is formed and a wavelength filter that passes the wavelength λ ₂ is formed on the other light-receiving surface, of the optical signals of wavelengths λ ₁ and λ ₂ transmitted through one optical fiber, only an optical signal of wavelength lambda ₁ from the wavelength filter side of lambda ₁ is selectively taken out, the light receiving surface of the other side, only the optical signal of the wavelength lambda ₂ is selectively removed.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of a light receiving element according to the present invention. In the figure, the light-receiving element of this embodiment is provided with two light-receiving surfaces 5 and 6 on the element body 4 via the groove 18, and the light-receiving surface 5 side is provided with the two light-receiving surfaces 5 and 6 as shown in FIG. , The wavelength filter 7 showing high reflection for the wavelength λ _{1 and} low reflection for the wavelength λ ₂ , that is, the wavelength filter 7 for selectively taking in only the optical signal of the wavelength λ ₁ is the dielectric multilayer film. And a semiconductor layer, the light-receiving surface 6 side exhibits low reflection for wavelength λ _{1 and} high reflection for wavelength λ ₂ as shown in FIG. The wavelength filter 8 shown, that is, the wavelength filter 8 that selectively takes in only the optical signal of the wavelength λ ₂ is similarly formed by using a dielectric multilayer film or a semiconductor layer. Electrodes 9 are provided around the respective wavelength filters 7 and 8 so as to be electrically connected to the corresponding light receiving surfaces 5 and 6.

Therefore, according to the light receiving element of this embodiment, the optical signals transmitted through one optical fiber are simultaneously incident on the light receiving surfaces 5 and 6, but the optical signal incident on the light receiving surface 5 is a wavelength filter. The signal of wavelength λ ₁ is selectively extracted by passing through 7 and converted into an electrical signal of wavelength λ ₁ , and the optical signal of wavelength λ ₂ is selectively extracted from the optical signal incident on the light receiving surface 6 by the wavelength filter 8. Wavelength taken out by λ ₂
As a result of being converted into the electric signal of, the two kinds of optical signals having the wavelengths of λ ₁ and λ ₂ can be branched by using one light receiving element, converted into the electric signal and taken out from the electrode 9.

As described above, since the wavelengths λ ₁ and λ ₂ can be branched and extracted with one light receiving element, the optical branching component 2 and the optical fibers 1a and 1b, which are essential in the conventional system, are provided. It becomes unnecessary, and the light receiving element is 1
Since it is sufficient to use only one, it is possible to reduce the number of parts of the system of the light receiving portion, and it is possible to achieve simplification of the system configuration and cost reduction of the system construction.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, two light receiving surfaces 10 are provided on the element body 4.
11 is formed, the light receiving surface 10 side is formed as a diffusion region 12 that receives both wavelengths λ ₁ and λ _2, and a passivation film 13 that blocks the flow of current is formed on the surface around the diffusion region 12. An electrode 14 is formed on the inner end side of the passivation film 13 so as to be electrically connected to the diffusion region 12.

On the other hand, on the light receiving surface 11 side, a diffusion region 12 is formed in the same manner as on the light receiving surface 10 side, and 1.3 μ is formed above the diffusion region 12.
a semiconductor layer that absorbs a wavelength λ ₁ of m, that is, 1.3 μm
InGaAsP having a composition of wavelength λ of <λ <1.55 μm
Is formed into a wavelength filter 15, and the upper surface side of the wavelength filter 15 is covered with a passivation film 13 leaving a region corresponding to the diffusion region 12. An electrode 16 is formed on the inner end side of the passivation film 13 so as to be electrically connected to the wavelength filter 15.
In FIG. 3, 17 is an electrode for applying a bias voltage.

Also in this embodiment, the wavelengths λ ₁ and λ supplied from one optical fiber are the same as in the first embodiment.
The optical signal ₂ is incident on the light receiving surfaces 10 and 11. At this time, both the optical signals of wavelengths λ ₁ and λ ₂ are taken into the light receiving surface 10 side. On the other hand, the optical signal incident on the light-receiving surface 11 side is a wavelength filter.
Since the signal of wavelength λ ₁ is absorbed by 15, the wavelength λ ₁
Only the _2nd signal is selectively extracted. Therefore, on the signal processing side, by subtracting the signal of wavelength λ ₂ captured on the light receiving surface 11 from the signals of λ ₁ and λ ₂ captured on the light receiving surface 10 side, a signal of λ ₁ is obtained, Since the signal of λ ₂ is obtained from the side of the light receiving surface 11, it becomes possible to extract optical signals of two different wavelengths of λ ₁ and λ ₂ by one light receiving element, which is the same as the first embodiment. In addition, the number of parts in the light receiving part is reduced to simplify the system configuration,
A low cost system can be constructed.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, in the above-described embodiment, one light receiving element is provided with two light receiving surfaces, but three or more light receiving surfaces may be provided. Also in this case, one or more light-receiving surfaces are provided with wavelength filters for selectively extracting optical signals of desired wavelengths.

[0014]

According to the present invention, one element is provided with a plurality of light receiving surfaces, and a wavelength filter is formed on one or more of the plurality of light receiving surfaces. By inputting the optical signals of a plurality of wavelengths transmitted by the optical fiber of each book into each light receiving surface, the optical signals of a plurality of wavelengths can be extracted in a branched state. Therefore, the optical branching component, which was indispensable in the conventional system, is unnecessary, and the plurality of light receiving elements for each wavelength, which are indispensable in the conventional example, are also unnecessary, and the number of components is very small. It is possible to construct a low-cost system by simplifying the system configuration of the light receiving portion. In this way, it becomes possible to provide an epoch-making light receiving element that has never existed before, and it is possible to make a great contribution to the development of optical communication.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing a first embodiment of a light receiving element according to the present invention.

FIG. 2 is a characteristic explanatory diagram of two types of wavelength filters formed in the light receiving element of the embodiment.

FIG. 3 is a configuration explanatory view showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a conventional general light receiving element together with a system of a light receiving portion of optical communication.

[Explanation of symbols]

 4 Element body 5,6,10,11 Light receiving surface 7,8,15 Wavelength filter 12 Diffusion region

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04B 10/22

Claims (1)

[Claims] 1. A plurality of light receiving surfaces are provided on one element,
A light receiving element in which a wavelength filter is formed on one or more of the plurality of light receiving surfaces.