JP2002111632A - Method and apparatus for transmission and reception of light signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus wherein two serial digital data are converted into light signals having different central wavelengths, they are multiplexed so as to be transmitted and received through an optical fiber, the two serial digital data are regenerated within a reasonable cost range, and a necessary transmission quality can be ensured. SOLUTION: First serial digital data is converted into a first light signal by using a 1.3 μm-band FP laser diode 31. Second serial digital data is converted into a second light signal by using a 1.55 μm-band DFB laser diode 33. The first and second light signals are multiplexed so as to obtain a multiplexed light signal. When the light signal is sent out to an optical fiber transmission line 19, a multiplexing part 15 is formed by using a fiber-type WDM coupler as a multiplexing means. As a light branching part 21 which receives the transmitted signals so as to obtain two regenerated light signals, a light branching part of superior isolation characteristic is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The invention described in the claims of the present application relates to, for example, two serial digital data based on two digital video data obtained from two video cameras, respectively, having different center wavelengths. An optical signal transmission / reception method for converting the two optical signals into two optical signals, transmitting the signals through an optical fiber transmission line, receiving the optical signals transmitted through the optical fiber transmission line, and reproducing the original two serial digital data; and The present invention relates to an optical signal transmitting / receiving apparatus used for carrying out such a method.

[0002]

2. Description of the Related Art In the field of transmission of digital information signals representing various kinds of information such as image information, the digital information signals are converted into serial digital data, and the serial digital data is formed using a coaxial cable or twisted pair line. A data transmission system for transmitting data through a transmission line, or an optical signal transmission system for converting serial digital data into an optical signal and transmitting the optical signal through an optical transmission line formed using an optical fiber, has been put into practical use. ing. Among these, the optical signal transmission system has an extremely large transmission signal capacity of the optical transmission line, and excellent transmission efficiency can be easily obtained.

On the other hand, in the field of video signals, digitization has been attempted from the viewpoint of diversifying transmitted information and realizing high quality reproduced images. For example, digitized video signals, Video camera that generates digital video signals (digital video camera device)
Etc. have been put to practical use. Then, serial digital data based on the digital video signal from the video camera is obtained so that the digital video signal obtained from the video camera can be transmitted by the optical signal transmission system. It has been proposed to convert this into an optical signal representing

When transmitting an optical signal based on a digital video signal obtained from a video camera through an optical transmission line formed using optical fibers in an optical signal transmission system, a digital video signal obtained from one video camera is used. In some cases, it is necessary not only to transmit an optical signal based on a digital video signal but also to simultaneously transmit two optical signals based on two digital video signals obtained from two video cameras, for example. When simultaneous transmission of two optical signals is required as described above, it is naturally desired that the required optical transmission path can be easily obtained and the transmission efficiency is good. Therefore, for example, it is conceivable that two optical signals are multiplexed and transmitted through a common optical transmission line.

As described above, when simultaneous transmission of two optical signals based on two digital video signals respectively obtained from two video cameras is required, the digital video signals obtained from each video camera are usually standardized. It follows the data format specified. As digital video signals conforming to such a standardized data format, HD digital video signals (HD signals), 4: 2: 2 component digital video signals (D1 signals), 4fsc composite digital video signals (D2 signals), and the like. It has been known.

[0006] Taking the HD signal out of these, the HD signal follows a data format as shown in FIG. 9, for example.

The data format shown in FIG. 9 is a luminance signal data sequence (Y data sequence) representing a luminance signal component in a video signal as shown in FIG. 9A.
And a color difference signal data sequence (P _B / P _R) representing a color difference signal component in the video signal as shown in FIG.
Data series), Y data series and P _B / P _R
Each of the word data forming each of the data series is 1
It has a 0-bit configuration. That is, the Y data series and P _B /
Each of the _PR data sequences is a 10-bit quantized digital signal. FIG. 9A shows a line blanking period in each line period in the Y data series and a portion corresponding to a part of the video data period before and after the line blanking period. FIG. It has been shown a portion corresponding to a portion of the video data period of the horizontal blanking period and before and after in each line period in the P _B / P _R data sequence.

In the Y data series, immediately before the portion corresponding to each video data period, four words (3FF (Y), 000 (Y), 000) each having a 10-bit configuration.
(Y), XYZ (Y)) are provided, and four words each having a 10-bit structure are provided immediately after a portion corresponding to each video data period. (3FF
(Y), 000 (Y), 000 (Y), XYZ (Y))
Timing reference code data (EAV: Endo
f Active Video). Similarly, P _B / P _R
Even in the data sequence, immediately before the portion corresponding to each video data period, four words each having a 10-bit configuration (3FF (C), 000 (C), 000 (C), XYZ
(C)), and immediately after the portion corresponding to each video data period, four words (3FF (C), 000 (C),
000 (C), XYZ (C)). Of course, EAV and SAV Each of the in Y data sequence, Y data is arranged in a portion corresponding to the line blanking period in the sequence, also people P _B / P _R data in the sequence of the EAV and SAV husband, P disposed in a portion corresponding to the line blanking period in _B / P _R data sequence.

[0009] In such Y data sequence and P _B / P _R data sequence is transmitted, Y data sequence and P _B /
The P _R data sequence, word multiplexing process at Moto the portion corresponding to the line blanking period, each of EAV and SAV are disposed has been made to the synchronization is performed, the word multiple data series as shown in FIG. 10 , Formed as a 10-bit quantized digital signal. Then, the digital video signal converted into a 10-bit quantized digital signal according to the word multiplexed data sequence is converted into serial digital data and transmitted for transmission.

In the word multiplexed data series, immediately before a portion corresponding to each video data period, 8 words (3FF (C), 3FF
(Y), 000 (C), 000 (Y), 000 (C),
000 (Y), XYZ (C), XYZ (Y)), and a 10-bit structure immediately after a portion corresponding to each video data period. 8 words (3FF
(C), 3FF (Y), 000 (C), 000 (Y),
000 (C), 000 (Y), XYZ (C), XYZ
(Y)) is provided.

For example, when HD signals are obtained from each of two video cameras, serial digital data based on each of the two HD signals is formed, and the serial digital data is converted into an optical signal. Then, the two optical signals obtained as a result are multiplexed and transmitted through a common optical transmission line. In this case, the two optical signals to be multiplexed have different center wavelengths, and the respective center wavelengths are selected according to the characteristics of the optical fiber constituting the optical transmission line.

There are various types of optical fibers, and one of them is a quartz single mode fiber (quartz SMF). This quartz-based SMF has, for example, a core diameter of 10 μm, a cladding diameter of 125 μm, and a single propagation mode, a wide transmission frequency band, and low propagation loss. Therefore, it is suitable for high-speed and long-distance communication using optical signals, and is suitable for transmitting optical signals based on HD signals obtained from a video camera.

Such a quartz-based SMF is, for example, shown in FIG.
The optical signal is attenuated according to the attenuation characteristic shown in FIG. 1 and the optical signal is dispersed according to the dispersion characteristic shown in FIG. The dispersion of an optical signal refers to the spread of the frequency spectrum of the optical signal and the spread of the propagation time or waveform distortion of the optical signal caused by the material and structure of the optical fiber.
In the attenuation characteristic shown in FIG.
It shows the minimum value of attenuation for light having a wavelength of μm and light having a wavelength of approximately 1.55 μm. Further, in the dispersion characteristics shown in FIG. 12, the dispersion of light having a wavelength of about 1.3 μm is minimized.

Under these circumstances, for example, quartz-based SMF
The two optical signals transmitted by multiplexing the optical transmission line constituted by the following formulas have respective center wavelengths at wavelengths near the minimum value of attenuation in the attenuation characteristics shown in FIG. 1.3 μm and 1.55 μm are selected. That is, in converting serial digital data based on the HD signal obtained from one of the two video cameras into an optical signal, a light source in the 1.3 μm band is used, and the light is obtained from the other of the two video cameras. In converting serial digital data based on the HD signal into an optical signal, a light source in the 1.55 μm band is used.

[0015]

As described above, under the condition that an HD signal is obtained from each of the two video cameras, two serial digital data based on the two HD signals are formed, and the serial digital data is formed. The digital data is converted into two optical signals having center wavelengths of 1.3 μm and 1.55 μm, respectively, and multiplexed to obtain a silica-based signal.
When an optical signal transmission system is constructed to transmit through a common optical transmission line constituted by MFs, 1.3 μm
The light source of the band and the light source of the 1.55 μm band are, for example, 1.3
It is formed using a μm band laser diode and a 1.55 μm band laser diode. Further, a multiplexer for multiplexing two optical signals having central wavelengths of 1.3 μm and 1.55 μm, respectively, and a central wavelength of 1.3 μm and 1.55 μm from the combined optical signals. A demultiplexer that separates and extracts two optical signals is used.

A 1.3 μm band laser diode, 1.55 μm, used for constructing such an optical signal transmission system.
When the m-band laser diode, the multiplexer, the demultiplexer, and the like are provided, if they have excellent performance, the cost will be significantly increased and the cost can be suppressed. If it were,
The transmission quality may be degraded, and transmission of the optical signal may be hindered. In the related art, there is no optical signal transmission system as described above, in which the cost is kept within an appropriate range and the required transmission quality is ensured.

In view of the above, the invention described in the claims of the present application, for example, converts two serial digital data based on two HD signals respectively obtained from two video cameras into different center wavelengths. Converted into two optical signals having, multiplexed and multiplexed them, for example,
The optical signal is transmitted through a common optical fiber transmission line composed of silica-based SMF, and the multiplexed optical signal transmitted through the optical fiber transmission line is demultiplexed to obtain two optical signals having different center wavelengths. In converting and reproducing digital data, the required cost can be kept within a reasonable range.
Provided is an optical signal transmitting / receiving method capable of securing necessary transmission quality, and an optical signal transmitting / receiving apparatus provided for implementing the method.

[0018]

An optical signal transmission / reception method according to any one of claims 1 to 7 in the claims of the present application provides a method for transmitting / receiving first serial digital data to / from a first serial digital data. A first optical signal having a center wavelength is converted into a first optical signal, and the second serial digital data is converted into a second optical signal having a second center wavelength. Performing multiplexing processing using a multiplexing means to obtain a multiplexed optical signal based on the first and second optical signals, transmitting the multiplexed optical signal to an optical fiber transmission line, and transmitting the multiplexed optical signal transmitted through the optical fiber transmission line. Receiving
The transmitted multiplexed optical signal is subjected to demultiplexing processing using a demultiplexing unit having excellent isolation characteristics as compared with the case where the above-described multiplexing unit is used as a demultiplexing unit, and the multiplexed optical signal transmitted A first reproduction optical signal having a first center wavelength and a second reproduction optical signal having a second center wavelength based on the first reproduction optical signal and converting the first reproduction optical signal into first reproduction serial digital data. In addition to the conversion, the second reproduced optical signal is converted to second reproduced serial digital data.

An optical signal transmitting / receiving apparatus according to any one of claims 8 to 14 of the present application has the first serial digital data having the first center wavelength. A first light-to-light conversion unit for converting a first optical signal, a second light-to-light conversion unit for converting the second serial digital data to a second light signal having a second center wavelength, and a first light A multiplexing unit that performs multiplexing processing on a signal and a second optical signal using a multiplexing unit, obtains a multiplexed optical signal based on the first and second optical signals, and sends the multiplexed optical signal to an optical fiber transmission line. And the multiplexed optical signal transmitted through the optical fiber transmission line,
A demultiplexing process is performed using a demultiplexing device having excellent isolation characteristics as compared with the case where the above-described demultiplexing device is used as a demultiplexing device, and a first center wavelength based on the transmitted multiplexed optical signal is provided. A demultiplexer for obtaining the first reproduced optical signal and the second reproduced optical signal having the second center wavelength, and a first demultiplexer for converting the first reproduced optical signal into first reproduced serial digital data. It is configured to include a photoelectric conversion unit and a second photoelectric conversion unit that converts a second reproduced optical signal into second reproduced serial digital data.

The optical signal transmission / reception method according to any one of claims 1 to 7 in the claims of the present invention as described above, or claims 8 to 8 in the claims of the present application. In the optical signal transmission / reception device according to any one of the inventions described in any one of (1) to (14), the first optical signal and the second optical signal are combined to obtain a multiplexed optical signal, and the multiplexed optical signal is transmitted to an optical fiber transmission line. In the transmission, for example, as in the case of the optical signal transmission / reception method according to the invention described in claim 4 or the optical signal transmission / reception apparatus according to the invention described in claim 11, a fiber type wavelength multiplexing coupler (fiber type WDM) is used. Coupler) is used as a multiplexing means, and when a multiplexed optical signal transmitted through an optical fiber transmission line is demultiplexed to obtain a first reproduced optical signal and a second reproduced optical signal, for example, Fiber type WDM coupler is branching means excellent isolation characteristics compared to when used as a branching means are used. Such demultiplexing means having excellent isolation characteristics is described in, for example, claim 5.
As in the case of the optical signal transmitting / receiving method according to the invention described in (1) or the optical signal transmitting / receiving device according to the invention described in (12), a fiber-type WDM coupler incorporating a blocking filter for an undesired optical signal is separated. The optical signal transmission / reception method according to the invention described in claim 6 or the optical signal transmission / reception device according to the invention described in claim 13 includes a dielectric multi-layer film. The configured demultiplexing means. Fiber-type WDM couplers used as multiplexing means are generally inexpensive.

By doing so, the conversion of the first serial digital data into the first optical signal is performed using, for example, a 1.3 μm band Fabry-Perot (FP) laser diode and the second optical signal. The conversion of the serial digital data into the second optical signal is, for example, 1.55
This can be performed using a μm band distributed feedback (DFB) laser diode. The 1.3 μm-band FP laser diode oscillates in a multi-wavelength mode and emits laser light having a wavelength spectrum of, for example, about 8 nm. The temperature characteristic of the center wavelength is, for example, about 0.4 nm / ° C. And low price. On the other hand, a 1.55 μm band DFB laser diode oscillates in a single wavelength mode and emits a laser beam having substantially a single wavelength.
It is about 0.2 nm / ° C., not low cost.

The conversion of the first serial digital data into a first optical signal is performed using a 1.3 μm band FP laser diode, and the conversion of the second serial digital data into a second optical signal. When a 1.55 μm band DFB laser diode is used, the first optical signal and the second optical signal are multiplexed to obtain a multiplexed optical signal, which is transmitted to an optical fiber transmission line.
A fiber-type WDM coupler is used as a multiplexing means. In addition, when a multiplexed optical signal transmitted through an optical fiber transmission line is demultiplexed to obtain a first reproduced optical signal and a second reproduced optical signal, a fiber-type WDM coupler is used. When a WDM coupler is used as a demultiplexing unit, for example, 1.3 μm
The output from the fiber-type WDM coupler constituting the demultiplexing means has suffered a crosstalk failure due to a change in the center wavelength due to a temperature change according to the temperature characteristic of the center wavelength of the m-band FP laser diode. As a result, there is a possibility that a necessary transmission quality may not be ensured.

On the other hand, the optical signal transmitting / receiving method according to the invention described in any one of claims 1 to 7 in the claims of the present application, or claims 8 to 8 in the claims of the present application. According to the optical signal transmitting and receiving apparatus of the invention described in any one of the above items 14, the first optical signal and the second optical signal are multiplexed to obtain a multiplexed optical signal, and the multiplexed optical signal is transmitted to the optical fiber transmission line. In sending, for example,
A fiber-type WDM coupler is used as a multiplexing means, and a multiplexed optical signal transmitted through an optical fiber transmission line is demultiplexed to obtain a first reproduced optical signal and a second reproduced optical signal. Type WDM
A demultiplexing unit having excellent isolation characteristics as compared with a case where a coupler is used as a demultiplexing unit, for example, a fiber type W having a built-in blocking filter for an undesired optical signal.
Since a DM coupler is used as a demultiplexing unit or a demultiplexing unit provided with a dielectric multilayer film is used, for example, the temperature characteristic of the 1.3-μm band FP laser diode at the center wavelength described above is used. A situation in which the output from the demultiplexer receives a crosstalk failure due to a change in the center wavelength due to the temperature change is avoided, and necessary transmission quality is secured.

The optical signal transmitting / receiving method according to any one of the first to seventh aspects of the present invention or the eighth to fourteenth aspects of the present invention. According to the optical signal transmitting / receiving apparatus according to any one of the above aspects, the conversion of the first serial digital data into the first optical signal is performed, for example, by:
A low-cost 1.3 μm band FP laser diode is used. Further, the first optical signal and the second optical signal are multiplexed to obtain a multiplexed optical signal, which is transmitted to an optical fiber transmission line. In doing so, a low-cost fiber-type WDM coupler can be used as the multiplexing means, so that the required cost is kept within a reasonable range.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing an example of an optical signal transmission / reception method according to the invention described in any one of claims 1 to 7 of the present application. An example of the optical signal transmitting / receiving device according to the invention described in any one of claims 8 to 14 in the claims is shown.

In the example shown in FIG. 1, on the transmitting side, the HD signal DHDA is transmitted from the video camera 11 and the HD signal DHDB is transmitted from the video camera 12.
Is sent. These HD signals DHDA and DHDB
Each, for example, multiplexing processing in the Y data sequence and the P _B / P _R data series as shown in FIG. 9 is obtained is subjected to a 20-bit quantized digital signal, a word transmission rate 74.25 MBps.

HD signal D obtained from the video camera 11
The HDA is serialized by a parallel / serial (P / S) converter 13 and has a bit transmission rate of 74.25.
Serial digital data DSA with MBps × 20 = 1.485 Gbps is transmitted from the P / S converter 13. The serial digital data DSA is an electric / optical (E)
/ E) is supplied to the conversion unit 14, and the E / O conversion unit 14 performs an electro-optical conversion process on the serial digital data DSA.

The E / O converter 14 includes, for example, a laser driver 30 and a 1.3 μm band FP laser diode 31 as shown in FIG. And P /
Serial digital data DSA from S converter 13
Is supplied to the laser driving unit 30, and a laser driving signal SLDA corresponding to the serial digital data DSA is obtained from the laser driving unit 30 and supplied to the 1.3 μm band FP laser diode 31.

1.3 μm band FP laser diode 31
Oscillates in a multi-wavelength mode, and emits a laser beam having a wavelength spectrum of about 8 nm with a center frequency of about 1.31 μm, for example, as shown in FIG. For example, it is about 0.4 nm / ° C. The 1.3 μm band FP laser diode 31 to which the laser drive signal SLDA has been supplied converts the 1.3 μm band laser light having a center wavelength of approximately 1.31 μm to the laser drive signal SLDA.
, With a state modulated by
An optical signal OVA having a center wavelength of approximately 1.31 μm based on the serial digital data DSA is output from the O conversion unit 14.
Is obtained with the bit transmission rate set to 1.485 Gbps. This optical signal OVA is supplied to the multiplexing unit 15.

On the other hand, the HD obtained from the video camera 12
The signal DHDB is serialized by the P / S converter 16 and the bit transmission rate is set to 74.25 MBps × 20 =
1.485 Gbps serial digital data D
The SB is transmitted from the P / S converter 16. The serial digital data DSB is supplied to the E / O conversion unit 17,
The E / O conversion unit 17 performs an electro-optical conversion process on the serial digital data DSB.

For example, as shown in FIG. 4, the E / O converter 17 is provided with a laser driver 32 and a 1.55 μm band DFB.
The laser diode 33 is provided. And
Serial digital data DS from P / S converter 16
B is supplied to the laser drive unit 32 and the laser drive unit 32
, A laser drive signal SLDB corresponding to the serial digital data DSB is obtained.
It is supplied to the B laser diode 33.

DFB laser diode 3 in 1.55 μm band
3 oscillates in a single wavelength mode and emits a laser beam having a center frequency of about 1.55 μm, for example, as shown in FIG. 5, and the temperature characteristic of the center wavelength is, for example, 0.2 nm /
It is about ° C. The 1.55 μm band DFB laser diode 33 to which the laser drive signal SLDB is supplied emits a 1.55 μm band laser beam having a center wavelength of about 1.55 μm in a state modulated by the laser drive signal SLDB. , The center wavelength based on the serial digital data DSB from the E / O converter 17 is approximately 1.
An optical signal OVB having a thickness of 55 μm is obtained with a bit transmission rate of 1.485 Gbps. This optical signal OVB is supplied to the multiplexing unit 15.

The multiplexing unit 15 is, for example, a fiber type WD
Formed by M coupler. The multiplexing unit 15 formed by the fiber type WDM coupler is configured as shown in FIG. 6, for example.

In the configuration shown in FIG. 6, an optical signal OVA having a center wavelength of approximately 1.31 μm from the E / O converter 14 is transmitted through the optical connector 35 to the directional coupler 36.
And an optical signal OVB from the E / O conversion unit 17 having a center wavelength of about 1.55 μm is transmitted to the optical connector 3.
Through 7, it is guided to the directional coupling section 36. The directional coupling portion 36 is a portion where an optical fiber for guiding light through the optical connector 35 and an optical fiber for guiding light through the optical connector 37 are mutually coupled. In the directional coupler 36, the optical signal OV having a center wavelength of approximately 1.31 μm
A and an optical signal OVB having a center wavelength of about 1.55 μm are multiplexed and multiplexed, and a multiplexed optical signal OVM is transmitted. The multiplexed optical signal OVM obtained in the directional coupler 36 is led out through the optical connector 38.

As described above, the multiplexed optical signal OVM derived from the multiplexing unit 15 is guided to the optical fiber transmission line 19 through the optical connector 18 and transmitted to the receiving side through the optical fiber transmission line 19. Optical fiber transmission line 19
Is, for example, the attenuation characteristic as shown in FIG.
Is formed using a silica-based SMF having the dispersion characteristics as shown in FIG.

On the receiving side, the optical fiber transmission line 1
The multiplexed optical signal OVM transmitted through 9 is guided to the demultiplexing unit 21 through the optical connector 20. The demultiplexing unit 21
The fiber type WDM coupler forming the multiplexing unit 15 is formed by a demultiplexing unit having excellent isolation characteristics as compared to a case where it is assumed that the fiber type WDM coupler is used as a demultiplexing unit. In the case where a fiber-type WDM coupler is used as a demultiplexing unit, a port for demultiplexing an optical signal OVA having a center wavelength of about 1.31 μm from the multiplexed optical signal OVM and deriving the center wavelength from the multiplexed optical signal OVM FIG. 7 shows the insertion loss characteristics of the port that divides and derives the optical signal OVB of approximately 1.55 μm. In FIG. 7, a curve a indicates an insertion loss of an output port for deriving an optical signal OVA having a center wavelength of about 1.31 μm.
Curve b shows an optical signal OVB having a center wavelength of about 1.55 μm.
Is derived from the insertion loss of the output port.

A demultiplexing unit having excellent isolation characteristics as compared to a case where such a fiber-type WDM coupler is used as a demultiplexing unit is described in, for example, “1.
The first blocking filter for light in the wavelength band including the center wavelength of 55 μm and the second blocking filter for light in the wavelength band including the center wavelength of about 1.31 μm have a center wavelength of about 1.31 μm. Optical signal through which the optical signal OVA passes and the optical signal O whose center wavelength is approximately 1.55 μm
Fiber-type WDM couplers (fiber-type W
DM coupler) is used as a demultiplexing means. The fiber type WDM coupler with a built-in rejection filter is configured, for example, as shown in FIG.

In the configuration shown in FIG. 8, the multiplexed optical signal OVM through the optical connector is guided to the directional coupler 41 through the optical connector 40. Directional coupling part 41
Is a portion where an optical fiber for guiding light through the optical connector 40 is divided into two optical fibers, and the two divided optical fibers form two output ports. The two output ports extending from the directional coupler 41 are provided with a central wavelength obtained by subjecting the multiplexed optical signal OVM to demultiplexing and mixed with an optical signal OVB having a central wavelength of approximately 1.55 μm by crosstalk. Optical signal OV of approximately 1.31 μm
A and the center wavelength of the optical signal OVA having the center wavelength of about 1.31 μm mixed by the crosstalk is about 1.55 μm.
And an optical signal OVA having a center wavelength of about 1.31 μm mixed with the optical signal OVB having a center wavelength of about 1.55 μm due to crosstalk.
Is guided to the 1.55 μm blocking filter input optical connector 42, and the center wavelength mixed with the optical signal OVA having the center wavelength of about 1.31 μm due to crosstalk is set to about 1.
The optical signal OVB of 55 μm is guided to the 1.31 μm blocking filter input optical connector 43.

1.55 μm blocking filter optical connector 4
2, optical signal OVA having a center wavelength of approximately 1.31 μm by a built-in 1.55 μm blocking filter.
The optical signal OVB having a center wavelength of about 1.55 μm mixed therein is removed, and the optical signal OVA having a center wavelength of about 1.31 μm has a bit transmission rate of 1.485 G.
The signal is reproduced under the condition of bps and is led out from the 1.55 μm blocking filter input connector 42. Also, 1.31μ
In the m-blocking filter input optical connector 43, the built-in 1.31 μm blocking filter converts the optical signal OVB having a center wavelength of approximately 1.55 μm from the optical signal OVA having a center wavelength mixed therein to approximately 1.31 μm. Is removed, and an optical signal OVB having a center wavelength of about 1.55 μm is
It is reproduced under the condition that the bit transmission rate is 1.485 Gbps, and is derived from the 1.31 μm blocking filter input optical connector 43.

According to the fiber-type WDM coupler with a built-in rejection filter shown in FIG. 8 that constitutes the demultiplexing unit 21, even an optical signal having a wavelength of 1.3 μm band has a wavelength of 1.55 μm band. For the optical signal
An isolation of 0 dB or more is obtained.

In another example of the demultiplexing section 21, a fiber type WD forming the multiplexing section 15 is formed.
A demultiplexing unit having better isolation characteristics than the case where the M coupler is used as the demultiplexing unit is, for example, a demultiplexing unit using a dielectric multilayer film. In the case of a demultiplexing means using such a dielectric multilayer film,
For an optical signal having a wavelength in the 1.3 μm band, isolation of 30 dB or more can be obtained, and 1.55 μm
Under the condition that the isolation of 45 dB or more is obtained for the optical signal having the wavelength in the m band, the multiplexed optical signal OVM is subjected to the demultiplexing process, and the optical signal OVA having the center wavelength of about 1.31 μm and the center wavelength Is approximately 1.55 μm.
VB has a bit transmission rate of 1.485 Gbps.
It will be played under that.

As described above, the demultiplexing unit 21 is connected to the multiplexing unit 15
That has excellent isolation characteristics as compared to the case where the fiber-type WDM coupler forming the above is used as the demultiplexing means, for example, the one in which a fiber-type WDM coupler with a built-in rejection filter is used as the demultiplexing means. Alternatively, by using a demultiplexing unit using a dielectric multilayer film, for example, approximately 1.31 μm of a 1.3 μm band FP laser diode used in the E / O conversion unit 14 is used.
The optical signal OVA whose central wavelength is approximately 1.31 μm derived from the demultiplexing unit 21 and whose central wavelength is approximately 1.31 μm due to the fluctuation of the central wavelength due to the temperature change according to the temperature characteristic of the central wavelength m Each of the optical signals OVB of 1.55 μm is assumed to have suffered a crosstalk failure, thereby avoiding a situation where required transmission quality is not ensured.

The optical signal OVA whose center wavelength is reproduced by the demultiplexer 21 and whose center wavelength is approximately 1.31 μm, and whose center wavelength is approximately 1.31 μm.
The optical signal OVB of 55 μm is supplied to optical / electrical (O / E) converters 22 and 23, respectively. O / E converter 22
, An optical signal O having a center wavelength of about 1.31 μm
O / E conversion is performed on VA to set the center wavelength to approximately 1.31 μm.
The bit transmission rate based on the optical signal OVA is 1.
485 Gbps serial digital data DSA
To play. Then, the reproduced serial digital data DSA is converted into a serial / parallel (S / P) converter 2.
4 is supplied. The S / P converter 24 performs S / P conversion on the serial digital data DSA, and generates a 20-bit quantized digital signal having a word transmission rate of 74.25 MBps based on the serial digital data DSA. The signal DHDA is reproduced, and the reproduced HD signal DHDA is supplied to the camera control unit 25.

In the camera control unit 25, the HD
Correction of the signal DHDA, conversion to an analog video signal, and the like are performed.

In the O / E converter 23, the optical signal OVB having a center wavelength of about 1.55 μm is subjected to O / E conversion to obtain an optical signal OV having a center wavelength of about 1.55 μm.
The serial digital data DSB whose bit transmission rate is 1.485 Gbps based on B is reproduced. The reproduced serial digital data DSB is represented by S
/ P conversion unit 26. The S / P conversion unit 26 performs S / P conversion on the serial digital data DSB, and based on the serial digital data DSB, outputs a 20-bit quantized digital signal having a word transmission rate of 74.25 MBps. The signal DHDB is reproduced, and the reproduced HD signal DHDB is supplied to the camera control unit 27.

In the camera control unit 27, the HD
Correction of the signal DHDB, conversion to an analog video signal, and the like are performed.

[0047]

As is apparent from the above description, the optical signal transmitting / receiving method according to any one of the first to seventh aspects of the present invention or the optical signal transmitting / receiving method according to the first aspect of the present invention. According to the optical signal transmitting and receiving apparatus according to any one of claims 8 to 14, E / O conversion is performed on each of the first serial digital data and the second serial digital data. In multiplexing the first optical signal and the second optical signal obtained as described above to obtain a multiplexed optical signal and transmitting the multiplexed optical signal to an optical fiber transmission line, for example, a fiber-type WDM coupler is used as a multiplexing means. Is performed, and the multiplexed optical signal transmitted through the optical fiber transmission line is demultiplexed to obtain a first reproduced optical signal and a second reproduced optical signal, respectively. In order to obtain the real digital data and the second reproduced serial digital data, the above-mentioned multiplexing means is a demultiplexing means which is superior in isolation characteristics to the case where the fiber type WDM coupler is used as the demultiplexing means. For example, a demultiplexing unit using a fiber type WDM coupler having a built-in blocking filter for an undesired optical signal, or a demultiplexing unit using a dielectric multilayer film is used. Thereby, the conversion of the first serial digital data into the first optical signal is performed, for example,
In addition to using a 1.3 μm band FP laser diode, the conversion of the second serial digital data into a second optical signal can be performed using, for example, a 1.55 μm band DFB laser diode. , 1.3
The output from the demultiplexing means is not subject to crosstalk failure due to the fluctuation of the center wavelength due to the temperature change according to the temperature characteristic of the center wavelength of the μm band FP laser diode, and the necessary transmission quality is secured. Is done.

The optical signal transmitting / receiving method according to any one of claims 1 to 7 in the claims of the present application, or claims 8 to 14 in the claims of the present application. According to the optical signal transmitting / receiving apparatus according to any one of the above aspects, the conversion of the first serial digital data into the first optical signal is performed, for example, by:
A low-cost 1.3 μm band FP laser diode is used. Further, the first optical signal and the second optical signal are multiplexed to obtain a multiplexed optical signal, which is transmitted to an optical fiber transmission line. In doing so, a low-cost fiber-type WDM coupler is used as the multiplexing means, so that the required cost is kept within a reasonable range.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for transmitting and receiving an optical signal according to one of the first to seventh aspects of the present invention. It is a block connection diagram which shows an example of the optical signal transmission / reception apparatus which concerns on any one of claim | item 8 to claim 14.

FIG. 2 is a block diagram illustrating a specific configuration example of an E / O conversion unit used in the example of FIG. 1;

FIG. 3 is a characteristic diagram for explaining a 1.3 μm band FP laser diode used in the specific configuration example of FIG. 2;

FIG. 4 is a block diagram illustrating a specific configuration example of an E / O conversion unit used in the example of FIG. 1;

FIG. 5 shows 1.55 μm used in the specific configuration example of FIG.
FIG. 4 is a characteristic diagram used for describing a band DFB laser diode.

FIG. 6 is a block diagram showing a specific configuration example of a multiplexing unit used in the example of FIG. 1;

FIG. 7 is a characteristic diagram used for describing a specific configuration example in FIG. 6;

FIG. 8 is a block diagram showing a specific configuration example of a demultiplexing unit used in the example of FIG. 1;

FIG. 9 is a time chart showing a data format of a Y data sequence and a P _B / P _R data sequence forming a digital video signal.

FIG. 10 is a time chart showing a data format of a word multiplex data sequence forming a digital video signal.

FIG. 11 is a characteristic diagram showing an attenuation characteristic of a quartz-based SMF.

FIG. 12 is a characteristic diagram showing dispersion characteristics of a quartz-based SMF.

[Explanation of symbols]

11, 12 ... video camera, 13, 16 ... P
/ S converter, 14, 17 ... E / O converter, 15
... Combining parts, 18, 20, 35, 37, 38, 40
... optical connector, 19 ... optical fiber transmission line,
21 ... demultiplexing unit, 22, 23 ... O / E conversion unit, 24, 26 ... S / P conversion unit, 25, 27 ...
・ Camera control unit, 30, 32 ・ ・ ・ Laser driver, 31 ・ ・ ・ 1.3μm band FP laser diode,
33 ... 1.55 μm band DFB laser diode,
36, 41 ... directional coupling part, 42 ... 1.5
5 μm blocking filter optical connector, 43... 1.3
1μm blocking filter optical connector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/232 H04B 9/00 C 7/22

Claims (14)

[Claims] 1. A method for converting first serial digital data into a first optical signal having a first central wavelength and converting second serial digital data into a second optical signal having a second central wavelength. Performing multiplexing processing on the first optical signal and the second optical signal using a multiplexing unit to obtain a multiplexed optical signal based on the first and second optical signals; To the optical fiber transmission line, receive the multiplexed optical signal transmitted through the optical fiber transmission line, and isolate the transmitted multiplexed optical signal from the transmitted multiplexed optical signal as compared with the case where the multiplexing means is used as the demultiplexing means. A demultiplexing process is performed using a demultiplexing means having an excellent multiplexing characteristic, and a first reproduced optical signal having the first central wavelength and the second central wavelength based on the transmitted multiplexed optical signal are provided. And a second reproduced optical signal obtained by Converts the first reproduction light signal to the first reproduction serial digital data, optical signal transmission and reception method characterized by converting the second reproduction light signal to the second reproduction serial digital data. 2. The method according to claim 1, wherein the first serial digital data is modulated by modulating a laser beam emitted by first laser means for emitting a laser beam having a first center wavelength in accordance with the first serial digital data. 1 optical signal, and modulates the laser light emitted by the second laser means for emitting a laser light having a second center wavelength in accordance with the second serial digital data. 2. The optical signal transmitting / receiving method according to claim 1, wherein the digital data is converted into a second optical signal. 3. The method according to claim 2, wherein the first laser means is a 1.3 μm band Fabry-Perot type laser diode, and the second laser means is a 1.55 μm band distributed feedback laser diode. Optical signal transmission and reception method. 4. A multiplexed light based on the first and second optical signals by subjecting the first optical signal and the second optical signal to multiplexing processing using a fiber type wavelength multiplexing coupler as multiplexing means. 4. The optical signal transmission / reception method according to claim 1, wherein a signal is obtained. 5. A multiplexed optical signal transmitted through an optical fiber transmission line includes a first blocking filter for light in a wavelength band including a second center wavelength and a second blocking filter for light in a wavelength band including the first center wavelength. A demultiplexing process is performed by using a fiber type wavelength multiplexing coupler having a built-in blocking filter as a demultiplexing means to obtain first and second reproduced optical signals based on the transmitted multiplexed optical signal. The optical signal transmission / reception method according to any one of claims 1 to 4. 6. A multiplexed optical signal transmitted through an optical fiber transmission line is subjected to a demultiplexing process using a demultiplexing means provided with a dielectric multilayer film, based on the transmitted multiplexed optical signal. 5. The optical signal transmitting / receiving method according to claim 1, wherein first and second reproduced optical signals are obtained. 7. A method for obtaining first serial digital data by subjecting first digital video data obtained from a first video camera to parallel / serial conversion, and for converting second serial digital data to a second video camera. 7. The optical signal transmission / reception method according to claim 1, wherein the second digital video data is obtained by subjecting the second digital video data to parallel / serial conversion. 8. A first electro-optical converter for converting the first serial digital data into a first optical signal having a first center wavelength, and converting the second serial digital data into a first optical signal having a second center wavelength. A second electro-optical converter for converting the first and second optical signals into a second optical signal and a first optical signal and a second optical signal. A multiplexing unit that obtains a multiplexed optical signal based on the signal and sends the multiplexed optical signal to an optical fiber transmission line; and receives a multiplexed optical signal transmitted through the optical fiber transmission line and converts the multiplexed optical signal into the transmitted multiplexed optical signal. Performing a demultiplexing process using a demultiplexing unit having excellent isolation characteristics as compared with the case where the multiplexing unit is used as a demultiplexing unit, and performing the first center wavelength based on the transmitted multiplexed optical signal. And the second reproduced optical signal having A demultiplexing unit that obtains a second reproduced optical signal having a heart wavelength; a first photoelectric conversion unit that converts the first reproduced optical signal into first reproduced serial digital data; An optical signal transmission / reception device comprising: a second photoelectric conversion unit that converts an optical signal into second reproduced serial digital data. 9. The method according to claim 1, wherein the first light-to-light conversion unit modulates the laser light emitted by the first laser means for emitting the laser light having the first center wavelength in accordance with the first serial digital data. While converting the first serial digital data into a first optical signal, the second electro-optical converter converts the laser light emitted by the second laser means for emitting a laser light having a second center wavelength into a second optical signal. By modulating according to serial digital data,
9. The optical signal transmitting / receiving apparatus according to claim 8, wherein said second serial digital data is converted into a second optical signal. 10. The method according to claim 9, wherein the first laser means is a 1.3 μm band Fabry-Perot laser diode, and the second laser means is a 1.55 μm band distributed feedback laser diode. Optical signal transmitting and receiving device. 11. An optical signal transmitting / receiving apparatus according to claim 8, wherein said multiplexing section uses a fiber type wavelength multiplexing coupler as multiplexing means. 12. A demultiplexing unit, as a demultiplexing unit having excellent isolation characteristics as compared with a case where a fiber-type wavelength division multiplexing coupler is used as a demultiplexing unit, for demultiplexing light in a wavelength band including the second center wavelength. 12. A fiber type wavelength division multiplexing coupler having a built-in second blocking filter for light in a wavelength band including the first blocking filter and the first center wavelength. Optical signal transmitting and receiving device. 13. A demultiplexing unit comprising a dielectric multilayer film as a demultiplexing unit having excellent isolation characteristics as compared with a case where a fiber-type wavelength multiplexing coupler is used as a demultiplexing unit. The optical signal transmission / reception device according to any one of claims 8 to 11, wherein: 14. A first parallel / serial converter for performing parallel / serial conversion on first digital video data obtained from a first video camera to obtain first serial digital data, and a second video camera. And a second parallel / serial conversion unit for performing a parallel / serial conversion on the second digital video data obtained from the second to obtain the second serial digital data. An optical signal transmitting / receiving device according to any one of the above.