JP2001086073A - Optical transmission system and optical transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical transmission system capable of extending transmission distance at comparatively low cost, when one core two-way communications are performed by using a light source to generate optical signals with wavelengths of 1.3 μm and 1.55 μm. SOLUTION: In the optical transmission system provided with an optical fiber cable 14 as a transmission line and also provided with an optical transmitter 10 connected on one end of the transmission line and an optical transmitter 12 connected with the other end of the transmission line and performing the one core two-way communications between the optical transmitter 10 and the optical transmitter 12 via the transmission line, the transmission line is a single- mode optical fiber in which dispersion becomes zero, when the optical signal in a 1.3 μm band is transmitted, a Fabry-Perot laser diode to oscillate the light in the 1.3 μm band is used as a light source by either one of the optical transmitters 10, 12, and a distributed feedback laser diode to oscillate light in a 1.55 μm band is uses as the light source by the other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission system and an optical transmission apparatus for performing single-fiber communication using an optical fiber using two types of optical signals having different wavelengths.

[0002]

2. Description of the Related Art An optical transmission system and an optical transmission device of this kind are used when a long-distance LAN is connected without using a WAN (Wide Area Network) in a large-scale office or a local government having a private optical network. Used.

[0003]

In the case of a single mode optical fiber (SMF), which is frequently laid as a communication cable, the chromatic dispersion of an optical signal in the 1.55 μm band is large. In such a system, when an inexpensive Fabry-Perot laser diode is used, an optical signal having a wavelength of 1.3 μm is not distorted even if communication is performed at a transmission speed of about 100 Mbps, but an optical signal having a wavelength of 1.55 μm is not distorted. The waveform is disturbed by the influence of dispersion. For this reason, the transmission distance is limited by the communication system that transmits the optical signal having the wavelength of 1.55 μm.

That is, an emission spectrum of a Fabry-Perot laser diode (FP-LD) has a plurality of peaks as shown in FIG. In addition, the center wavelength discretely changes depending on the ambient temperature and the modulation state. The spectrum width between each peak in a Fabry-Perot laser diode that oscillates light in the 1.55 μm band is about 1.2 n.
m, the chromatic dispersion of an optical signal in the 1.55 μm band of a single mode optical fiber is generally referred to as 17.5 [ps / nm · km]. Assuming that one peak of the emission spectrum shifts during communication based on this condition, the transmission path length becomes 30
The difference in propagation delay time when transmitting an optical signal to a km single-mode optical fiber is 630 ps. As described above, since the propagation delay time frequently changes, the optical transmission waveform (eye pattern) after long-distance transmission is disturbed, and there is a problem that the transmission possible distance when a Fabry-Perot laser diode is used is limited. .

On the other hand, by using a distributed feedback laser diode (DFB-LD) for outputting an optical signal having a very narrow spectral width as shown in FIG. be able to. However, a distributed feedback laser diode is expensive, and requires an optical isolator because the laser oscillation in which reflected return light from the connector connection point enters the inside of the laser diode becomes unstable. Therefore, in an optical transmission system that performs single-fiber bidirectional communication using two types of optical signals having different wavelengths, both laser diodes serving as light sources for generating light in the 1.3 μm and 1.55 μm bands are distributed feedback. In the case of using a laser diode, there is a problem that the cost is extremely high as compared with a Fabry-Perot laser diode which does not require an optical isolator.

The present invention has been made in view of such circumstances, and is relatively inexpensive when performing single-fiber bidirectional communication using a light source that generates optical signals having wavelengths of 1.3 μm and 1.55 μm. It is an object of the present invention to provide an optical transmission system and an optical transmission device that can extend the transmission distance.

[0007]

According to a first aspect of the present invention, an optical fiber is used as a transmission line.
A first optical transmission device connected to one end of the transmission line, and a second optical transmission device connected to the other end of the transmission line;
In an optical transmission system for performing single-fiber bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission line, the transmission line transmits an optical signal in a wavelength band of 1.3 μm. A single-mode optical fiber whose dispersion becomes zero when
One of the first and second optical transmission devices uses a Fabry-Perot laser diode that oscillates light in a 1.3 μm band as a light source, and the other is a distributed feedback laser diode that oscillates in a 1.55 μm band. Is used as a light source.

According to a second aspect of the present invention, an optical fiber is used as a transmission line, and a first optical transmission device connected to one end of the transmission line and a second optical transmission device connected to the other end of the transmission line. An optical transmission system having an optical transmission device and performing single-core bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission line. 55 μm
A dispersion-shifted optical fiber whose dispersion becomes zero when transmitting an optical signal in a band, wherein one of the first and second optical transmission devices is a distributed feedback laser that oscillates light in the 1.3 μm band. A diode is used as a light source, and the other has a wavelength of 1.5
A Fabry-Perot laser diode that oscillates light in the 5 μm band is used as a light source.

Further, the invention according to claim 3 has a wavelength of 1.3.
A single mode optical fiber having zero dispersion when transmitting an optical signal in the μm band is used as a transmission line, and a first optical transmission device connected to one end of the transmission line, and a first optical transmission device connected to the other end of the transmission line. Optical transmission device having a second optical transmission device to perform single-fiber bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission path , One of the first and second optical transmission devices has a wavelength of 1.
A Fabry-Perot laser diode that oscillates light in the 3 μm band is used as a light source, and the other is that a distributed feedback laser diode that oscillates light in the 1.55 μm band is used as a light source.

[0010] The invention according to claim 4 has a wavelength of 1.5.
A dispersion-shifted optical fiber having zero dispersion when transmitting an optical signal in the 5 μm band is used as a transmission line, a first optical transmission device connected to one end of the transmission line, and a first optical transmission device connected to the other end of the transmission line. An optical transmission system having an optical transmission system for performing single-fiber bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission path. One of the first and second optical transmission devices uses a distributed feedback laser diode that oscillates light in a 1.3 μm band as a light source, and the other uses a Fabry-Perot that oscillates light in a 1.55 μm band. It is characterized in that a laser diode is used as a light source.

According to a fifth aspect of the present invention, in the optical transmission system according to the first or second aspect, the first and second optical transmission devices are the transmission line and a metallic line. Having a function of relaying the optical signal received via the transmission line to an electric signal and transmitting the electric signal to the other transmission line, and the electric signal received from the other transmission line. It is an optical converter that converts the signal into an optical signal and sends the signal to the transmission line.

According to a sixth aspect of the present invention, in the optical transmission device of the optical transmission system according to any one of the third and fourth aspects, the first and second optical transmission devices are each provided with a metallic and It has a function of relaying with another transmission line that is a line, converts an optical signal received via the transmission line into an electric signal, sends it out to the other transmission line, and receives it from the other transmission line. It is an optical converter that converts the electrical signal into an optical signal and sends it to the transmission line.

According to the first and fifth aspects of the present invention, an optical fiber is used as a transmission line, and the first fiber connected to one end of the transmission line is used.
Optical transmission device, and a second optical transmission device connected to the other end of the transmission line, between the first optical transmission device and the second optical transmission device via the transmission line In the optical transmission system for performing single-fiber two-way communication, the transmission path has a wavelength of 1.3.
a single-mode optical fiber whose dispersion becomes zero when transmitting an optical signal in the μm band, wherein one of the first and second optical transmission devices oscillates light in the 1.3 μm band; A perforated laser diode is used as a light source, and the other is a distributed feedback laser diode that oscillates light in a wavelength band of 1.55 μm.
It is possible to extend the transmission distance relatively inexpensively compared to the case of using a distributed feedback laser diode in both the m-band and the 1.55 μm wavelength band.

According to the second and fifth aspects of the present invention, the optical fiber is used as a transmission line, and the first fiber connected to one end of the transmission line is used.
Optical transmission device, and a second optical transmission device connected to the other end of the transmission line, between the first optical transmission device and the second optical transmission device via the transmission line In the optical transmission system that performs single-fiber two-way communication, the transmission path has a wavelength of 1.5.
A dispersion-shifted optical fiber whose dispersion becomes zero when transmitting an optical signal in the 5 μm band, and one of the first and second optical transmission devices is a distributed feedback that oscillates light in the 1.3 μm band. Since a laser diode is used as a light source, and the other uses a Fabry-Perot laser diode that oscillates light in a 1.55 μm band as a light source, the wavelength is 1.3.
In both the μm band and the 1.55 μm band, the transmission distance can be extended as compared with the case where a Fabry-Perot laser diode is used, and the 1.3 μm band and the 1.55 μm band can be used.
The configuration can be made relatively inexpensively as compared with the case where the distributed feedback laser diode is used in both wavelength bands of the μm band.

According to the third and sixth aspects of the present invention, a single mode optical fiber having zero dispersion when transmitting an optical signal in the 1.3 μm wavelength band is used as a transmission line, and is provided at one end of the transmission line. A first optical transmission device connected thereto, and a second optical transmission device connected to the other end of the transmission line, wherein the first optical transmission device and the second optical transmission device are connected via the transmission line. An optical transmission device for an optical transmission system for performing single-fiber bidirectional communication with a transmission device, wherein one of the first and second optical transmission devices emits light in a 1.3 μm band. Since a diode is used as a light source and a distributed feedback laser diode that oscillates light in a 1.55 μm band is used as a light source on the other side, a 1.3 μm band and a wavelength of 1.3 μm are used.
The transmission distance can be extended relatively inexpensively as compared with the case where the distributed feedback laser diode is used in both wavelength bands of the 55 μm band.

According to the fourth and sixth aspects of the present invention, a dispersion-shifted optical fiber having zero dispersion when transmitting an optical signal in the 1.55 μm band is used as a transmission line, and is connected to one end of the transmission line. A first optical transmission device, and a second optical transmission device connected to the other end of the transmission line, wherein the first optical transmission device and the second optical transmission device are connected via the transmission line. In the optical transmission device of the optical transmission system performing one-fiber bidirectional communication with the device, one of the first and second optical transmission devices is a distributed feedback laser diode that oscillates light in a 1.3 μm band. Is used as a light source, and the other uses a Fabry-Perot laser diode that oscillates light in a wavelength of 1.55 μm as a light source.
The transmission distance can be extended as compared with the case where the Fabry-Perot laser diode is used in both the wavelength bands of 55 μm, and the case where the distributed feedback laser diode is used in both the wavelength bands of 1.3 μm and 1.55 μm. This makes it possible to make the configuration relatively inexpensive.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows the configuration of the optical transmission system according to the first embodiment of the present invention. In the figure, the optical transmission system includes optical transmission devices 10 and 12.
And a single optical fiber cable 14. The optical transmission system according to the embodiment of the present invention is, for example, an Ethernet (registered trademark) type LAN (Local Area Network).
rk), the optical transmission devices 10 and 12
Are connected to bridges 20 and 22 as LAN devices via metallic cables 16 and 18, respectively.

The optical fiber cable 14 has a wavelength of 1.3 μm.
This is a single mode optical fiber in which the dispersion becomes zero when transmitting an m-band optical signal, and has a line length of several tens km. The metallic cables 16 and 18 are, for example, twisted pairs. The optical transmission device 10 converts an electric signal input via the bridge 20 and the metallic cable 16 into a 1.3 μm optical signal and outputs the optical signal to the optical fiber cable 14, and the optical transmission device 12 transmits the optical signal via the optical fiber cable 14 from the optical transmission device 12. The input optical signal is converted into an electric signal and output to the bridge 20 via the metallic cable 16.

The optical transmission device 12 converts an electric signal input through the bridge 22 and the metallic cable 18 into an optical signal of 1.55 μm and converts the electric signal into an optical fiber cable 14.
And converts the optical signal input from the optical transmission device 10 via the optical fiber cable 14 into an electric signal, and outputs the electric signal to the bridge 22 via the metallic cable 18. The optical transmission device 10 uses a Fabry-Perot laser diode that oscillates light in the 1.3 μm band as a light source for generating an optical signal, and the optical transmission device 12 uses a 1.55 μm band as a light source for generating an optical signal. A distributed feedback laser diode that oscillates light of the following type is used. With the above configuration, single-fiber bidirectional optical communication is performed between the optical transmission device 10 and the optical transmission device 12. The optical transmission devices 10 and 12 have basically the same configuration, and differ only in the laser diode used for the light source.

Next, a specific configuration of the optical transmission device 10 is shown in FIG. In FIG. 1, an optical transmission device 10 includes a buffer 30 for temporarily holding data when transmitting and receiving,
SE-FX driver 40 and 100BASE-FX receiver section 42
, A 100BASE-TX driver 50, a 100BASE-TX receiver unit 52, an optical transmission unit 60, an optical reception unit 70, a link control unit 80, an SC connector 82, an RJ4
5 connector 84. Reference numeral 90 denotes a clock signal generator that supplies a clock signal to each unit, and reference numeral 92 denotes a power supply circuit that supplies a predetermined power supply voltage to each unit.

The SC connector 82 is an optical fiber cable 1
4 and an RJ45 connector 84.
Is a connector connected to the twisted pair wire 16. The buffer 30 is composed of FIFOs 32 and 34,
2 stores data obtained by converting an optical signal into an electric signal,
The FIFO 34 stores data of an electric signal input via the twisted pair line 16.

The 100BASE-FX driver section 40 includes a parallel / serial converter 401 for converting parallel data into serial data, and an encoder 4 for encoding serial data output from the parallel / serial converter 401.
02 and a 100BASE-FX driver 403. Also, the 100BASE-FX receiver unit 42 is
0, a 100BASE-FX receiver 421 for receiving the photoelectrically converted electric signal captured via the O.0, a decoder 422 for decoding an output signal of the 100BASE-FX receiver 421,
A serial / parallel converter 423 for converting serial data, which is output data of the decoder 422, into parallel data and outputting the parallel data to the FIFO 32.

The 100BASE-TX driver unit 50
A parallel / serial converter 501 that converts parallel data read from the IFO 3 into serial data, a scrambler and an encoder that encodes and encrypts serial data output from the parallel / serial converter 501 into a predetermined format And a 100BASE-TX driver 503 for controlling output data of the scrambler and the encoder 502 to the twisted pair line 14. Also, the 100BASE-TX receiver unit 52
100BASE-TX that receives an electric signal (data of a predetermined format) received via the RJ45 connector 84
A decoder and descrambler 522 for converting an encrypted signal of the receiver 521 and the 100BASE-TX receiver 521 into an original signal sequence and decoding the same, and a serial / parallel for converting an output of the decoder and the descrambler 522 to parallel data. And a converter 523.

Further, the optical transmission unit 60 includes a laser diode (LD) 62 as a light source for generating an optical signal to be transmitted to the optical fiber cable 14, and a monitor used as a light receiving element for monitoring the emission intensity of the laser diode 62. An automatic light quantity control circuit (APC) 66 for adjusting the light emission output of the laser diode 62 based on the light emission output of the monitoring photodiode 64;
A laser diode (LD) driver 67 driven by the 00BASE-FX driver 4034 to output a control signal for driving the laser diode 62 to the automatic light amount control circuit 66; and an abnormal light emission state of the laser diode 62 (including an unlit state). (LD) abnormality detection circuit 68 for detecting Here, the laser diode (LD) 62 is a 1.3 μm Fabry-Perot laser diode.

The optical receiving unit 70 includes a photodiode 72 for receiving a 1.55 μm optical signal received from the optical transmission device 12 via the optical fiber cable 14 and the SC connector 82, and a preamplifier 74 for amplifying the output of the photodiode 72. , A post-amplifier 76, and a switch 77 provided between the output terminal of the post-amplifier 76 and the input terminal of the 100BASE-FX receiver 421 and controlled to open and close by the output of the link monitor 78. The link monitor 78 outputs the output from the preamplifier 74 at a predetermined level (normal level).
The switch 77 is turned on only when a signal is input, and the link control unit 80 is always informed of the reception state of the signal from the SC connector 82 side. In the optical transmission system shown in FIG. 1, the link control unit 80 determines whether or not communication with the system on the optical fiber cable 14 side and the system on the twisted pair line 16 side is normally performed. Is displayed.

Next, FIG. 4 shows an optical signal waveform after transmitting a single-mode optical fiber having a line length of 30 km using a Fabry-Perot laser diode which oscillates light in a 1.3 μm band.
FIG. 5 shows optical signal waveforms after transmission through a single-mode optical fiber having a line length of 30 km using a Fabry-Perot laser diode that oscillates light in the 1.55 μm band. As is clear from these figures, the signal waveform in the wavelength band of 1.55 μm is significantly distorted with respect to the optical signal in the wavelength band of 1.3 μm which is not affected by chromatic dispersion. Conventionally, in single-fiber bidirectional optical communication, the transmission distance has been limited by signal waveform distortion in the wavelength band of 1.55 μm.

Next, FIG. 6 shows an optical signal waveform after transmitting a single-mode optical fiber having a line length of 30 km using a distributed feedback laser diode that oscillates light in the wavelength band of 1.55 μm. The equivalent waveform distortion is improved as compared with the case where an optical signal is transmitted using a Fabry-Perot laser diode that oscillates light in the 1.55 μm band shown in FIG. 5, and the wavelength is improved by using a distributed feedback laser diode. 1.55
The influence of chromatic dispersion in the μm band can be avoided.

Therefore, according to the optical transmission system according to the first embodiment of the present invention, as shown in FIG.
By using a Fabry-Perot laser diode that oscillates light in a band and using a distributed feedback laser diode having a wavelength of 1.55 μm as a laser diode in the optical transmission device 12, both wavelengths of 1.3 μm and 1.55 μm are used. It is possible to extend the transmission distance relatively inexpensively compared with the case of using a distributed feedback laser diode in a band.
Note that a distributed feedback laser diode having a wavelength band of 1.55 μm was used as a laser diode in the optical transmission device 10.
As a matter of course, the same effect can be obtained by using a Fabry-Perot laser diode that oscillates light in the 1.3 μm band as the laser diode in the optical transmission device 12.

Next, the configuration of an optical transmission system according to a second embodiment of the present invention is shown in FIG. In the figure, the optical transmission system has optical transmission devices 100 and 102 and a single optical fiber cable 104. The optical transmission system according to the embodiment of the present invention is, for example, an Ethernet type LAN (Local Area Network), as in the first embodiment.
work), the optical transmission devices 100, 1
02 are metallic cables 106 and 108, respectively.
Are connected to the bridges 110 and 112 as LAN devices via the LAN.

The optical fiber cable 14 has a wavelength of 1.55.
This is a dispersion-shifted optical fiber in which the dispersion becomes zero when transmitting an optical signal in the μm band, and has a line length of several tens km.
The metallic cables 106 and 108 are, for example, twisted pairs. The optical transmission device 100 converts an electric signal input through the bridge 110 and the metallic cable 106 into a 1.3 μm optical signal and outputs the optical signal to the optical fiber cable 14, and also outputs the optical signal from the optical transmission device 102 through the optical fiber cable 104. The input optical signal is converted into an electrical signal and converted into a bridge 110 through a metallic cable 106.
Output to

The optical transmission device 102 is connected to the bridge 11
2. The optical signal input through the metallic cable 108 is converted into an optical signal of 1.55 μm and output to the optical fiber cable 104, and the optical signal input from the optical transmission device 100 through the optical fiber cable 104 is converted into an optical signal. The signal is converted into an electric signal and output to the bridge 112 via the metallic cable 108. In the optical transmission device 100, a distributed feedback laser diode that oscillates light in the 1.3 μm band is used as a light source for generating an optical signal.
In No. 2, a wavelength of 1.55 μm was used as a light source for generating an optical signal.
A Fabry-Perot laser diode that emits light in a band is used.

With the above configuration, one-fiber bidirectional optical communication is performed between the optical transmission device 100 and the optical transmission device 102.
The optical transmission devices 100 and 102 have basically the same configuration, except for the laser diode used for the light source. The specific configuration of the optical transmission devices 100 and 102 is shown in FIG.
And the same description is omitted. According to the optical transmission system according to the second embodiment of the present invention, in FIG. 7, a distributed feedback laser diode that oscillates light in the 1.3 μm band is used as the laser diode in the optical transmission device 100. By using a Fabry-Perot laser diode having a wavelength of 1.55 μm as the laser diode in 102, the transmission distance is extended as compared with the case of using a Fabry-Perot laser diode in both the 1.3 μm wavelength band and the 1.55 μm wavelength band. In addition, the configuration can be made relatively inexpensively as compared with the case where the distributed feedback laser diode is used in both the 1.3 μm wavelength band and the 1.55 μm wavelength band.

[0033]

As described above, according to the first and fifth aspects of the present invention, an optical fiber is used as a transmission line, and the first optical transmission device connected to one end of the transmission line, A second optical transmission device connected to the other end of the transmission line, and performing single-fiber bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission line. In the optical transmission system, the transmission line is a single mode optical fiber having a dispersion of zero when transmitting an optical signal in a 1.3 μm wavelength band, and one of the first and second optical transmission devices. Is wavelength 1.
A Fabry-Perot laser diode that oscillates light in the 3 μm band is used as a light source, and a distributed feedback laser diode that oscillates light in the 1.55 μm band is used as the light source. 55 μm
The transmission distance can be extended relatively inexpensively compared with the case of using a distributed feedback laser diode in both wavelength bands.

According to the second and fifth aspects of the present invention, the optical fiber is used as a transmission line, and the first fiber connected to one end of the transmission line is used.
Optical transmission device, and a second optical transmission device connected to the other end of the transmission line, between the first optical transmission device and the second optical transmission device via the transmission line In the optical transmission system that performs single-fiber two-way communication, the transmission path has a wavelength of 1.5.
A dispersion-shifted optical fiber whose dispersion becomes zero when transmitting an optical signal in the 5 μm band, and one of the first and second optical transmission devices is a distributed feedback that oscillates light in the 1.3 μm band. Since a laser diode is used as a light source, and the other uses a Fabry-Perot laser diode that oscillates light in a 1.55 μm band as a light source, the wavelength is 1.3.
In both the μm band and the 1.55 μm band, the transmission distance can be extended as compared with the case where a Fabry-Perot laser diode is used, and the 1.3 μm band and the 1.55 μm band can be used.
The configuration can be made relatively inexpensively as compared with the case where the distributed feedback laser diode is used in both wavelength bands of the μm band.

According to the third and sixth aspects of the present invention, a single-mode optical fiber having a dispersion of zero when transmitting an optical signal in the 1.3 μm band is used as a transmission line, and is provided at one end of the transmission line. A first optical transmission device connected thereto, and a second optical transmission device connected to the other end of the transmission line, wherein the first optical transmission device and the second optical transmission device are connected via the transmission line. An optical transmission device for an optical transmission system for performing single-fiber bidirectional communication with a transmission device, wherein one of the first and second optical transmission devices emits light in a 1.3 μm band. Since a diode is used as a light source and a distributed feedback laser diode that oscillates light in a 1.55 μm band is used as a light source on the other side, a 1.3 μm band and a wavelength of 1.3 μm are used.
The transmission distance can be extended relatively inexpensively as compared with the case where the distributed feedback laser diode is used in both wavelength bands of the 55 μm band.

According to the fourth and sixth aspects of the present invention, a dispersion-shifted optical fiber having zero dispersion when transmitting an optical signal in the 1.55 μm band is used as a transmission line, and is connected to one end of the transmission line. A first optical transmission device, and a second optical transmission device connected to the other end of the transmission line, wherein the first optical transmission device and the second optical transmission device are connected via the transmission line. In the optical transmission device of the optical transmission system performing one-fiber bidirectional communication with the device, one of the first and second optical transmission devices is a distributed feedback laser diode that oscillates light in a 1.3 μm band. Is used as a light source, and the other uses a Fabry-Perot laser diode that oscillates light in a wavelength of 1.55 μm as a light source.
The transmission distance can be extended as compared with the case where the Fabry-Perot laser diode is used in both the wavelength bands of 55 μm, and the case where the distributed feedback laser diode is used in both the wavelength bands of 1.3 μm and 1.55 μm. This makes it possible to make the configuration relatively inexpensive.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical transmission system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of the optical transmission system shown in FIG.

FIG. 3 is a characteristic diagram showing optical output spectra of a Fabry-Perot laser diode and a distributed feedback laser diode.

FIG. 4 is a waveform diagram showing an optical signal waveform after transmitting a single-mode optical fiber having a line length of 30 km using a Fabry-Perot laser diode that oscillates light in a 1.3 μm band.

FIG. 5 is a waveform diagram showing an optical signal waveform after transmitting a single-mode optical fiber having a line length of 30 km using a Fabry-Perot laser diode that oscillates light in a wavelength band of 1.55 μm.

FIG. 6 is a waveform diagram showing an optical signal waveform after transmitting a single-mode optical fiber having a line length of 30 km using a distributed feedback laser diode which oscillates light in a wavelength band of 1.55 μm.

FIG. 7 is a diagram showing a configuration of an optical transmission system according to a second embodiment of the present invention.

[Explanation of symbols]

10, 12, 100, 102 Optical transmission device 14, 104 Optical fiber cable 16, 18, 106, 108 Twisted pair (metallic cable) 20, 22, 110, 112 Bridge

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nao Yamada 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Shinya Abe 1-1-5-1 Kiba, Koto-ku, Tokyo Stock Company F term in Fujikura (reference) 5K002 AA05 BA13 CA01 DA02 DA42 FA02

Claims (6)

[Claims] An optical fiber is used as a transmission line, comprising: a first optical transmission device connected to one end of the transmission line; and a second optical transmission device connected to the other end of the transmission line, In an optical transmission system for performing single-fiber bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission line, the transmission line transmits an optical signal in a wavelength band of 1.3 μm. In this case, the dispersion is zero, and one of the first and second optical transmission devices uses a Fabry-Perot laser diode that oscillates light in a 1.3 μm band as a light source, The other is an optical transmission system using a distributed feedback laser diode that oscillates light in the 1.55 μm band as a light source. 2. A transmission path comprising an optical fiber, a first optical transmission apparatus connected to one end of the transmission path, and a second optical transmission apparatus connected to the other end of the transmission path, In an optical transmission system for performing single-fiber bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission line, the transmission line transmits an optical signal in a wavelength band of 1.55 μm. In this case, one of the first and second optical transmission devices uses, as a light source, a distributed feedback laser diode that oscillates light in a 1.3 μm band. Is an optical transmission system using a Fabry-Perot laser diode that emits light in a wavelength band of 1.55 μm as a light source. 3. A single-mode optical fiber having zero dispersion when transmitting an optical signal in a 1.3 μm wavelength band is used as a transmission line.
A first optical transmission device connected to one end of the transmission line, and a second optical transmission device connected to the other end of the transmission line;
An optical transmission device of an optical transmission system for performing single-fiber bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission path, wherein the first and second optical transmission devices One of them uses a Fabry-Perot laser diode that oscillates light in a 1.3 μm band as a light source, and the other uses a distributed feedback laser diode that oscillates light in a 1.55 μm band as a light source. Optical transmission equipment for transmission systems. 4. A first optical transmission device connected to one end of a transmission line, wherein the transmission line is a dispersion-shifted optical fiber having a dispersion of zero when transmitting an optical signal in a 1.55 μm band.
A second optical transmission device connected to the other end of the transmission line, and a one-core bidirectional communication between the first optical transmission device and the second optical transmission device via the transmission line. In one of the first and second optical transmission devices, one of the first and second optical transmission devices uses a distributed feedback laser diode that oscillates light in a 1.3 μm band as a light source, and the other uses a distributed feedback laser diode. An optical transmission device for an optical transmission system, wherein a Fabry-Perot laser diode that emits light in a 55 μm band is used as a light source. 5. The first and second optical transmission devices have a function of relaying the transmission line and another transmission line which is a metallic line, and convert an optical signal received via the transmission line into an electric signal. 2. An optical converter which converts the signal into a signal and sends the signal to the other transmission path, converts an electric signal received from the other transmission path into an optical signal, and sends the signal to the transmission path. 3. The optical transmission system according to any one of 2. 6. The first and second optical transmission devices have a function of relaying the transmission line and another transmission line which is a metallic line, and convert an optical signal received via the transmission line into an electric signal. 4. An optical converter which converts the signal into a signal and sends the signal to the other transmission path, converts an electric signal received from the other transmission path into an optical signal, and sends the signal to the transmission path. Or the optical transmission device of the optical transmission system according to any one of 4.