JPS58111446A - Transmission and reception module of optical fiber - Google Patents

Abstract

PURPOSE:To eliminate crosstalk, by providing ground lines for transmission and reception systems separately in a transmission and reception module coupled with an optical communication line using optical fiber. CONSTITUTION:An optical signal transmitted in an optical fiber 15 is inputted to a photodetector 33 of a transmission and reception module 11, converted into an electric signal, amplified at an amplifier 35 and the output is given to an output terminal 41 of a connector 231. Power for the amplifier 35 is supplied from a terminal 43 and a ground line is connected to the 1st ground terminal 471. In the transmission side, an electric signal coming from an external device via an input terminal 45 and the 2nd ground terminal 472 is applied to a light emitting element 51. The element 51 converts the electric signal into an optical signal 53 and transmits the signal 53 to a transmission and reception module of a remote station through an optical fiber 17. Ground lines of the transmission and reception systems are wired separately and connected to the terminals 472 and 471 respectively, then the transmission and reception systems are not coupled and the module without crosstalk can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical fiber transmitting/receiving module used when performing optical communications using optical fibers, for example.

An example of a conventionally known optical fiber transceiver module is shown in FIG. The claw 9, one transmitting/receiving module 7 and /J are optically coupled by an optical fiber cable which is a bundle of optical fibers /j and /2. The module /1 is attached to an optical communication device (not shown) by a connector N provided on its outer casing, and the module 13 is connected electrically to an optical communication device (not shown) by a connector N provided directly outside the module. Conversion between electrical signals and optical signals between the electrical circuits included in both transceiver modules /l and /J and the optical fiber cable is performed by the respective signal converters S and -9.

Figure 1 shows one of the transmitter/receiver modules/l shown in Figure 1.
Specifically shown. Here, the light receiving element 3J receives the optical signal 3/ transmitted from the other module /J via the optical fiber an and converts it into an electrical signal. The electrical signal obtained by this is amplified by the amplifier 3S and then supplied to the output terminal bin 4 (/) of the connector.
The positive voltage terminal of j is connected to the positive voltage (+Vc) of the connector.
A power supply voltage is supplied through the terminal pin 4IJ.

In the transmission system of the transmitter/receiver module//, from the external device, input terminal pin 5 and ground terminal pink 7 of connector n
An electrical signal is applied between the two. The electrical signal is a light emitting element (LED)! / is transformed into an optical signal kJ,
This optical signal 53 is transmitted to the other module 73 via optical fiber /7. Connector N input terminal bin 41s
A resistor SS connected between the light emitting element 31 and the light emitting element 31 is a resistor that limits the current flowing through the light emitting element 31. When a visible light LED is used as the light emitting element /, a current of 10% x) mm will be passed through the light emitting element j/. This current flows in the direction indicated by the arrow a in the figure, at the connector n.
Is the ground terminal pink? (GND). The ground terminal pin of the amplifier 3j, one terminal of each of the light receiving element 3J and the light emitting element j/ are commonly connected to the ground terminal bin 417.

In other words, currents for the transmitting system and the receiving system commonly flow in this commonly connected line.

By the way, these circuit components are assembled on a printed circuit board 4/. There is a resistor in the pattern of the printed circuit board 6/ through which the transmission system current lR is woven. If the equivalent resistance value is R, a voltage drop go of Ro-iR occurs. Therefore, the voltage drop E0 is superimposed on the electrical signal obtained by the light receiving element 33 in the receiving system, which becomes the input signal of the amplifier 3j. That is, there is a drawback that the transmitted signal strongly influences the received signal, resulting in so-called crosstalk.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, it is an object of the present invention to provide an optical fiber transceiver module without crosstalk.

The present invention will be described in detail below based on the drawings.

FIG. 3 shows an embodiment of the present invention. Here, the difference from the conventional example shown in FIG. 1 is that the ground line of the transmitting system is separated from the ground line of the receiving system. Connect the common connection between one terminal of the light receiving cable 33 and the ground terminal of the amplifier 3j to the first ground terminal pin $7/ of the connector 3/ (
GND / ) and connect one terminal of the light emitting element to the ground terminal pin 41 of the connector 31. λ(GND
2). In this way, by making the ground lines of the transmitting line and the receiving system separate and independent, the voltage drop Re-1g due to the resistor Re of the pattern on the printed circuit board 41 will not have an adverse effect on the receiving side.

Therefore, crosstalk is eliminated. This also applies to the other transmitter/receiver module /J.

As described in detail above, according to the present invention, it is possible to realize an optical fiber transceiver module without crosstalk.

[Brief explanation of the drawing]

1st wA is a perspective view showing a conventional optical fiber transmitting/receiving module, Figure 1 is a block diagram showing an electrical circuit in a conventional optical fiber transmitting/receiving module, and Figure 3 is an optical fiber transmitting/receiving module according to the book @ Ming. FIG. 2 is a block diagram showing an electrical circuit in one embodiment. // , /, 3...transmission/reception module, /j,/fu...optical fiber, sword, -, ko3/...connector, 33...light receiving element, nail, da7,417/, Tougeko...Ground terminal bin, 3/...
...Light emitting element, 6th...Printed circuit board. Figure 3

Claims (1)

[Claims] 1) A transmitting system and a receiving system are housed in a module, and 41
In an optical fiber transmitter/receiver module that connects several modules (via an optical transmission path using a plurality of optical fibers), ground lines for the transmitting system and the receiving system in each of the transmitting/receiving modules are provided separately. Optical fiber transceiver module with % mold.