JPH0496435A - Device for single-fiber bidirectional optical communication - Google Patents

Abstract

PURPOSE:To remove the limit of a using method without utilizing a wavelength separation filter by composing an optical isolator of a first polarized beam splitter(PBS), magnet, Faraday element and second PBS, and arranging a photodetector in a side face vertical to the optical axis of the PBS. CONSTITUTION:The light of a wavelength emitted from a first laser diode 1 is passed through a lens 3, made incident to an optical isolator 9 composed of a first PBS 5, magnet 30, Faraday element 7 and second PBS 6, propagated from a lens 4 to an optical fiber 8 and made incident to a lens 4' and an optical isolator 9 similar to the optical isolator 9. Only the S wave is made incident to a photodetector 2' by a PBS 6' in the optical isolator 9'. Thus, single-fiber bidirectional optical communication is enabled without using the wavelength separation filter, and the using method is not limited.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical dataway connecting terminals having transmitting and receiving functions, and in particular to a single-fiber bidirectional optical device used for single-fiber bidirectional optical communication. be.

[Conventional technology]

FIG. 2 shows a device conventionally used for single-fiber bidirectional optical communication. ■ and 1' are laser diodes (hereinafter L
(Denoted as D), 2 and 2' are light receiving elements such as PIN photodiodes (hereinafter referred to as PD) 3.3', 4 and 4'
8 is a lens, 8 is an optical fiber, 9 and 9' are optical isolators, and 10 and 10' are wavelength separation filters.

The first LDI has a wavelength λ1, and the second LD l' has a wavelength λ
It emits light at 2. The first wavelength separation filter transmits light of wavelength A1 and reflects light of wavelength λ2.

Further, the second wavelength separation filter reflects light with wavelength λI and transmits light with wavelength λ2.

1 is the first LD, 3 is the lens, 9 is the optical isolator, 1
0 is the first wavelength separation filter, 4 is the lens, 2 is the PD
A device composed of these is called type A. 1' is the second LD, 3 is the lens, 9' is the optical isolator, 10' is the second wavelength separation filter, 4' is the lens, and 2' is the PD. The device consisting of these is called type B. call.

The light emitted from the first LDI passes through the lens 3, the optical isolator 9, the first wavelength separation filter 10, and the lens 4, and after being transmitted through the optical fiber 8, it is reflected by the second wavelength separation filter as a lens 4'. and enters the light receiving element 2'.

Conversely, the light emitted from the second LD 1' passes through the lens 3', the optical isolator 9', and the second wavelength separation filter 1.
0', passes through the lens 4', is transmitted through the optical fiber 8, passes through the lens 4, enters the first wavelength separation filter 10, is separated into wavelengths by the first wavelength separation filter 0', and is received. Light enters element 2. In this way, a device for single-fiber bidirectional optical communication is realized.

[Problem to be solved by the invention]

However, in conventional devices, single-fiber bidirectional optical communication can be performed from the type input side to the type B side or from the type B side to the Quib A side, but from the type input side to the type 8 side or from the type Single-fiber bidirectional optical communication from the B side to the Type B side cannot be performed, and the method of use is limited.

[Means to solve the problem]

Therefore, in the present invention, by performing single-core bidirectional communication without using or removing a wavelength separation filter, the method of use is no longer limited to type A from defect type 2 and from type B to type B. .

〔Example〕

An embodiment of the present invention will be described with reference to FIG. 1 and 1' are laser diodes (hereinafter referred to as LD), 2 and 2' are P
Light-receiving elements (hereinafter referred to as P
), 3.3', 4 and 4' are lenses, 8 is optical fiber 9 and 9' is an optical isolator, 5.5', 6
and 6' are PBS, 7 and 7' are Faraday elements, 3
0 and 30' are magnets.

The light with the wavelength λ1 emitted from the first LD] passes through the lens 3, enters the optical isolator 9, is transmitted from the lens 4 through the optical fiber 8, and then passes through the lens 4' and the optical isolator 9'. PBS in the optical isolator
6', only the S wave is incident on the light receiving element 2'.

In this way, single-fiber bidirectional optical communication becomes possible.

FIG. 3 shows another embodiment of the invention. 22.22'
is PD. Other symbols are the same as in FIG. light 1
Of the 00, the S wave is incident on the PD 22. P wave is PB
S6', the polarization angle is rotated by 45 degrees by Faraday element 7', and it enters PB35' as an S wave.
It is reflected by S6 and enters PD22'.

〔Effect of the invention〕

Conventional single-fiber bidirectional optical communication devices are divided into single-fiber bidirectional optical devices (type A) (hereinafter referred to as type A) versus type A and single-fiber bidirectional optical devices (type B) (hereinafter referred to as type B).
However, according to the present invention, the method of using type A versus type A and type B versus type B is limited. Since there are no limitations, convenience for the user is achieved. Moreover, since an expensive wavelength separation filter is not used, an inexpensive single-core bidirectional optical device can be provided.

[Brief explanation of drawings]

1'21 is a diagram showing an embodiment of the fiber-directed optical denoise according to the present invention, and FIG. 2 is a diagram used in a conventional single-fiber bidirectional optical communication system. FIG. 3 shows another embodiment of the invention. FIG. 4 shows a perspective view of the optical isolator of FIG. 1. 1 ・ ・ ・ 1 ・ ・ 2 2' 3, 3' 4 4' 5 5' 6 6' 7 7' 8 ・ ・ 9 9' 1st glue, I) 2nd L 1) 22 22' ・・PD ・Lens lens ・PBS ・PBS Faraday element ・Optical fiber ・Optical isolator 30' 1st wavelength separation filter ・2nd wavelength separation filter ・Single-core bidirectional optical communication device P A) ・Single-core bidirectional optical Communication device B) ...Magnet/light (Thailand (Thailand and beyond)

Claims (1)

[Claims] a laser diode and two or more lenses for coupling emitted light from the laser diode to an optical fiber;
In a single-core bidirectional optical communication module comprising an optical isolator disposed between two or more lenses, the optical isolator comprises a first polarizing beam splitter, a magnet, and a light receiving element, and the first PBS and A device for single-core bidirectional optical communication, characterized in that the Faraday element, the second PBS, and the magnet are arranged, and a light receiving element is arranged on a side surface in a direction perpendicular to the optical axis of the PBS. .