JPH1117657A - Optical transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost of an optical transmitter by so devising it that the transmission of a multi-channel video signal and a baseband digital pulse signal is made by means of a single transmission laser. SOLUTION: A frequency modulated light that is frequency-modulated at a frequency modulation laser 2 receiving a multi-channel video signal which is received from an input terminal 1 and a local light outputted from a local laser 3 are coupled at a photocoupler 4, and the optical signal coupled by the photocoupler 4 and an intensity modulation light resulting from intensity modulating a digital pulse signal received from an input terminal 6 by a digital pulse signal laser 7 are coupled by a photocoupler 8. Then a broad band FM signal is generated at a light-receiving element 5 by heterodyne detection between the FM modulated light and the local light, the intensity modulation light is photoelectric-converted so as to produce a digital pulse intensity modulated signal, and an electrical signal obtained by superimposing the broadband FM signal and the digital pulse intensity modulated signal is amplified by an amplifier 9, and the amplified signal is converted into an optical signal by a transmission laser 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission device for converting a multi-channel video signal into an optical signal and outputting the optical signal, and in particular,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission device that can convert a multi-channel video signal and a baseband digital pulse signal by collectively converting the multi-channel video signal into an FM signal.

[0002]

2. Description of the Related Art FIG. 14 shows the configuration of a conventional optical transmission device for transmitting a multi-channel video signal and a baseband digital pulse signal. lambda ₀ of the transmission laser 32 intensity modulation and outputs the optical signal, and transmits the laser 34 intensity modulation and outputs the optical signal of wavelength lambda ₁ digital pulse signal input to the input terminal 33, the wavelength lambda ₀ light an optical transmitter and an optical coupler 35 for multiplexing the optical signal of the signal and the wavelength lambda _1. Reference numeral 36 denotes an optical branch / optical fiber transmission line that branches and transmits an optical signal.

[0003] 37, the light with wavelength division multiplexing circuit (hereinafter referred to as "WDM") 38 for separating the optical signal and the wavelength lambda ₁ of the optical signal having a wavelength lambda ₀ of the optical signal input, an optical signal having a wavelength lambda ₀ A light-receiving element 39 for converting the electric signal and an amplifier 40 for amplifying and outputting the electric signal output from the light-receiving element 39 as a multi-channel video signal
And a light receiving element 41 for optical / electrical conversion of an optical signal of wavelength λ ₁
And an amplifier that amplifies and outputs an electric signal output from the light receiving element 41 as a digital pulse signal.

[0004] In the conventional optical transmission apparatus configured as described above, since the multi-channel video signal and the digital pulse signal occupy the same frequency band of 0 to 1 GHz,
The wavelength of the optical signal transmitting multichannel video signals, on a wavelength of the optical signal for transmitting digital pulse signals were converted to a different wavelength of the wavelength lambda ₀ and the wavelength lambda _1, respectively, it must be transmitted by the same optical fiber There is.

Therefore, the multi-channel video signal having the spectrum shown in FIG. 15A input to the input terminal 31 of the optical transmitter 30 is converted by the transmission laser 32 into an optical signal of wavelength λ ₀ . FIG. 15 (b) showing the input to the input terminal 33 of the optical transmitter 30.
The digital pulse signal of the spectrum shown in
It is converted to the wavelength lambda ₁ of the optical signal by 34. Then, these two optical signals are multiplexed by the optical coupler 35 and then transmitted from the optical transmitting device 30 to the optical receiving device 37 via the optical branching / optical fiber transmission line 36.

[0006] The multiplexed optical signal input to the optical receiver 37 is divided into two wavelengths λ ₀ and λ ₁ by the WDM 38.
Optical signals of two different wavelengths.

Therefore, the optical signal having the wavelength λ ₀ is transmitted to the light receiving element 39.
Is converted into a multi-channel video signal composed of electric signals having the spectrum shown in FIG. 15C, and the multi-channel video signal is amplified by the amplifier 40 and output.

The optical signal of wavelength λ ₁ is converted by the light receiving element 41 into a digital pulse signal composed of electric signals having the spectrum shown in FIG. 15D, and this digital pulse signal is amplified by the amplifier 42. Is output.

[0009]

However, in the optical transmission device having such a configuration, the multi-channel video signal and the digital pulse signal occupy the same frequency band of 0 to 1 GHz. Requires two transmission lasers 32 and 34 having different wavelengths, and the optical receiver 37 requires a WDM 38 for demultiplexing into two optical signals having different wavelengths. Since the light receiving element 39 and the light receiving element 41 are required, the price of the optical transmission device increases.

The present invention has been made to solve such a problem, and provides an optical transmission device capable of transmitting a multi-channel video signal and a baseband digital pulse signal with a single transmission laser. It is intended to be.

[0011]

An optical transmitting apparatus according to the present invention comprises:
2. The FM according to claim 1, wherein the oscillation frequency is FM-modulated by the multi-channel video signal input to the input terminal.
FM-modulated laser that outputs modulated light, local laser that outputs local light, digital pulse signal laser that outputs digital intensity-modulated light obtained by intensity-modulating a digital pulse signal input from an input terminal, FM-modulated light and local A first optical coupler for outputting an optical signal obtained by multiplexing any two of the light and the intensity-modulated light; and the optical signal output from the first optical coupler and the first optical coupler were not multiplexed. A second optical coupler that multiplexes any one of the FM modulated light, the local light, and the intensity modulated light, and generates a broadband FM signal by heterodyne detection of the FM modulated light and the local light, and converts the intensity modulated light into light. A light-receiving element that generates a digital pulse intensity modulation signal by performing electrical conversion, and outputs an electric signal obtained by superimposing the broadband FM signal and the digital pulse intensity modulation signal, and an output of the light-receiving element An amplifier for amplifying an electrical signal, is made of the transmission laser for converting an electric signal outputted by the amplifier into an optical signal.

According to a second aspect of the present invention, there is provided an optical transmitter comprising: an FM-modulated laser for outputting an FM-modulated light whose oscillation frequency is FM-modulated by a multi-channel video signal input to an input terminal; A local laser that outputs light, an optical modulator that outputs digital intensity-modulated light obtained by intensity-modulating a laser beam output from the laser with a digital pulse signal input to an input terminal, an FM-modulated light, a local light, and an intensity-modulated light A first optical coupler that outputs an optical signal obtained by multiplexing any two of the above, and an optical signal output from the first optical coupler and an FM-modulated light that is not multiplexed by the first optical coupler. A second optical coupler for multiplexing any one of the light and the intensity-modulated light, and a broadband FM signal generated by heterodyne detection of the FM-modulated light and the local light; On that caused the digital pulse intensity-modulated signal by conversion, a light receiving element for outputting an electric signal obtained by superimposing a broad-band FM signal and a digital pulse intensity-modulated signal,
An amplifier for amplifying the electric signal output from the light receiving element,
A transmission laser for converting the electric signal output from the amplifier into an optical signal.

Further, according to a third aspect of the present invention, there is provided an optical transmitter comprising: an FM-modulated laser for outputting an FM-modulated light whose oscillation frequency is FM-modulated by a multi-channel video signal input to an input terminal; A local laser that outputs light, and a digital local light that is intensity-modulated by a digital FM signal or a digital pulse signal whose local light is input to the input terminal. An optical modulator that outputs any one of optical signals, and any one of the optical signal output from the optical modulator, local light that has not been intensity-modulated by the optical modulator, and FM modulated light. Wave-coupled optical coupler, FM-modulated light or local light intensity-modulated by a digital pulse signal, and local light or F not intensity-modulated A broadband FM signal is generated by heterodyne detection with the modulated light, and a digital pulse signal is generated by optically / electrically converting the intensity modulated component of the FM modulated light or local light intensity-modulated by the digital pulse signal. A light receiving element for outputting an electric signal obtained by superimposing an FM signal and a digital pulse signal, an amplifier for amplifying the electric signal output from the light receiving element, and a transmission laser for converting the electric signal output from the amplifier to an optical signal; It consists of

Further, according to a fourth aspect of the present invention, there is provided an optical transmitter comprising: an FM-modulated laser for outputting FM-modulated light whose oscillation frequency is FM-modulated by a multi-channel video signal input to an input terminal; A local laser for outputting light, an optical coupler for outputting an optical signal in which the FM modulated light and the local light are combined, and an optical / electrical conversion of a broadband FM signal generated by heterodyne detection of the FM modulated light and the local light A light-receiving element for outputting an electric signal, a high-pass filter for passing an electric signal output from the light-receiving element, a low-pass filter for passing a digital pulse signal input to an input terminal, and a broadband FM signal output from the high-pass filter. A multiplexer that multiplexes the digital pulse signal output from the low-pass filter and outputs the multiplexed signal; An amplifier for amplifying the items, is made of the transmission laser for converting an electric signal outputted by the amplifier into an optical signal.

According to the present invention, a multi-channel video signal and a digital pulse signal are converted into a wideband FM signal, and the multi-channel video signal and the digital pulse signal are superimposed on each other. The transmission can be performed by one transmission laser, and the manufacturing cost of the optical transmission device can be reduced.

More specifically, the optical transmitter of the present invention comprises:
A digital pulse signal is converted to a frequency band of 0 to 1 GHz, and a wideband FM signal converted from a multi-channel video signal is converted to a 1G signal.
The multi-channel video signal and the digital pulse signal can be transmitted by one transmission laser by allocating the multi-channel video signal to a frequency band of Hz or more and batch-converting the multi-channel video signal into a broadband FM signal for transmission.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle and embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same reference numerals indicate the same parts.

FIG. 1 shows a multi-channel video signal converted from a broadband FM signal.
FIG. 2 is a block diagram for explaining the principle of the optical transmitter of the present invention for converting a signal into a signal. FIG. 2 shows waveforms output from each block in FIG.

When the multi-channel video signal a having the spectrum shown in FIG. 2A is input to the input terminal 1, the oscillation frequency of the FM-modulated laser 2 is increased by the multi-channel video signal a.
After being modulated, the FM modulated laser 2 outputs FM modulated light b having the spectrum shown in FIG.

The local laser 3 has an oscillation frequency of F
The local light c shown in FIG. 2C having a frequency separated by fc from the center frequency of the M modulated light b is output.

Then, when the optical coupler 4 outputs the optical signal d shown in FIG. 2D in which the FM modulated light b and the local light c are multiplexed, the light receiving element 5 makes the light modulated by the FM modulated light b and the local light c. By the heterodyne detection, the broadband FM signal e shown in FIG. 2E having the center frequency fc is output as a heterodyne beat signal.

Therefore, this broadband FM signal e is
When demodulated by a demodulator (not shown), a multi-channel video signal a having a spectrum shown in FIG. 2A is obtained.

FIG. 3 is a block diagram of an optical transmission device using the optical transmission device of the present invention, and FIG. 4 shows output signal waveforms of each block of the optical transmission device.

The multi-channel video signal a having the spectrum shown in FIG.
Is output from the FM modulation laser 2 in which the oscillation frequency is FM-modulated by the multi-channel video signal a.
Also, the local light is output from the local laser 3 and
An optical signal obtained by combining two optical signals of the M-modulated light and the local light is output from the optical coupler 4.

On the other hand, the baseband digital pulse signal f shown in FIG. 4B is input to the input terminal 6 and the intensity modulated light g obtained by intensity-modulating the digital pulse signal f is output from the digital pulse signal laser 7. Then, an optical signal obtained by multiplexing the optical signal output from the optical coupler 4 and the intensity-modulated light g output from the digital pulse signal laser 7 is output from the optical coupler 8.

Then, a broadband FM signal generated by heterodyne detection of the FM modulated light and the local light is superimposed on a digital pulse intensity modulated signal generated by optical / electrical conversion of the intensity modulated light g (FIG. 4 ()). The electric signal h having the spectrum shown in c) is output from the light receiving element 5. The electric signal h is amplified by the amplifier 9, converted into an optical signal by the transmission laser 10, and output from the transmission laser 10 of the optical transmitter to the optical branching / optical fiber transmission line 11. .

When an optical signal output from the transmission laser 10 of the optical transmitting apparatus is input to the light receiving element 12 of the optical receiving apparatus via the optical branch / optical fiber transmission line 11, the optical signal is transmitted to the light receiving element 12
Is converted into an electric signal h having the spectrum shown in FIG.
At 14 there are two branches.

Then, from one of the electric signals h branched by the branch circuit 14, a high-pass filter 15 is used as shown in FIG.
The broadband FM signal i having the spectrum shown in FIG. 4 is separated and output, and the broadband FM signal i is converted into a multi-channel video signal j having the spectrum shown in FIG.
M demodulated and output.

On the other hand, a low-pass filter 17 separates and outputs a baseband digital pulse signal k shown in FIG. 4 (f) from the other electric signal h branched by the branch circuit 14.

As described above, according to the optical transmission apparatus of the present invention, when the multi-channel video signal a and the digital pulse signal f are transmitted through the same optical branch / optical fiber transmission line 11, the multi-channel video signal a Transmission with the baseband digital pulse signal f can be performed by a single transmission laser 10.

(Embodiment 1) FIG. 5 shows the configuration of a first embodiment of the optical transmission apparatus according to the present invention. F modulated by channel video signal
An FM modulation laser that outputs M-modulated light, 3 is a local laser that outputs local light, and 4 is an optical coupler that outputs an optical signal that combines the FM-modulated light and local light.

Reference numeral 6 denotes an input terminal to which a digital pulse signal is input, 7 denotes a digital pulse signal laser that outputs a digital intensity-modulated light obtained by intensity-modulating the digital pulse signal, and 8 denotes an optical signal output by the optical coupler 4 and a digital pulse signal. The optical coupler outputs an optical signal obtained by multiplexing the intensity-modulated light output from the laser 7.

5 generates a broadband FM signal by heterodyne detection of the FM modulated light and the local light, generates a digital pulse intensity modulated signal by optically / electrically converting the intensity modulated signal, and generates a broadband FM signal. A light receiving element for outputting an electric signal superimposed with a digital pulse intensity modulation signal, 9 is an amplifier for amplifying the electric signal output from the light receiving element 5, and 10 is a transmission laser for converting the electric signal output from the amplifier 9 to an optical signal. It is.

In the present embodiment configured as described above, the oscillation frequency is FM-modulated by the multi-channel video signal input from the input terminal 1, and the FM modulation light output from the FM modulation laser 2 and the local laser 3 The two optical signals with the output local light are multiplexed by the optical coupler 4.

Further, an optical signal output from the optical coupler 4 and
The digital pulse signal input from the input terminal 6 is intensity-modulated, and two optical signals with the intensity-modulated light output from the digital pulse signal laser 7 are multiplexed by the optical coupler 8.

Then, a broadband FM signal is generated by heterodyne detection of the FM modulated light and the local light, and a digital pulse intensity modulated signal is generated by optically / electrically converting the intensity modulated light. The electric signal obtained by superimposing the digital pulse intensity modulation signal is
Output from Then, this electric signal is amplified by the amplifier 9, converted into an optical signal by the transmission laser 10, and output to the optical branching / optical fiber transmission line.

As described above, according to the present embodiment, a multi-channel video signal is converted into a wide-band FM signal and superimposed on a digital pulse signal, so that the multi-channel video signal and the digital pulse signal are transmitted in a single signal. It can be transmitted by the laser 10 for use.

In this embodiment, as shown in FIG. 5, two optical signals, that is, the FM modulated light output from the FM modulated laser 2 and the local light output from the local laser 3, are converted by the optical coupler 4. After being multiplexed, the optical signal output from the optical coupler 4 and the intensity-modulated light output from the digital pulse signal laser 7 are multiplexed by the optical coupler 8.

However, according to the present invention, as shown in FIG. 6, two optical signals of the FM modulated light output from the FM modulated laser 2 and the intensity modulated light of the digital pulse signal output from the digital pulse signal laser 7 are used. Are combined by the optical coupler 4, and the optical signal output from the optical coupler 4 and the local light output from the local laser 3 are combined into an optical coupler 8.
Thus, the same effect as in the embodiment of FIG. 5 can be obtained.

Further, according to the present invention, as shown in FIG. 7, two optical signals of a local light output from a local laser 3 and an intensity-modulated light of a digital pulse signal output from a digital pulse signal laser 7 are converted into optical signals. After being multiplexed by the coupler 4, the optical signal output from the optical coupler 4 and the FM modulated light output from the FM modulation laser 2 are multiplexed by the optical coupler 8. Similar effects can be obtained.

(Embodiment 2) FIG. 8 shows the configuration of an optical transmission apparatus according to a second embodiment of the present invention, in which 1 is an input terminal for inputting a multi-channel video signal, and 2 is an oscillation terminal having a large oscillation frequency. F modulated by channel video signal
An FM modulation laser that outputs M-modulated light, 3 is a local laser that outputs local light, and 4 is an optical coupler that outputs an optical signal that combines the FM-modulated light and local light.

Reference numeral 6 denotes an input terminal to which a digital pulse signal is input, reference numeral 18 denotes a laser that outputs laser light for transmitting a digital pulse signal, and reference numeral 19 denotes intensity of the laser light output from the laser 18 by the digital pulse signal input to the input terminal 6. An optical modulator 8 outputs a modulated digital intensity-modulated light, and an optical coupler 8 outputs an optical signal obtained by combining the optical signal output from the optical coupler 4 and the intensity-modulated light output from the optical modulator 19.

Reference numeral 5 denotes an electric signal obtained by superimposing a broadband FM signal generated by heterodyne detection of the FM modulated light and the local light and a digital pulse intensity modulated signal generated by performing optical / electrical conversion of the intensity modulated signal. An output light receiving element, 9 is an amplifier for amplifying the electric signal output from the light receiving element 5, and 10 is a transmission laser for converting the electric signal output from the amplifier 9 into an optical signal.

In the present embodiment configured as described above, the oscillation frequency is FM-modulated by the multi-channel video signal input from the input terminal 1 and the FM modulation light output from the FM modulation laser 2 and the local laser 3 The two optical signals with the output local light are multiplexed by the optical coupler 4.

The optical signal output from the optical coupler 4 is:
The laser light output from the laser 18 is intensity-modulated by the digital pulse signal input to the input terminal 6, and two optical signals with the intensity-modulated light output from the optical modulator 19 are multiplexed by the optical coupler 8.

Then, a broadband FM signal is generated by heterodyne detection of the FM modulated light and the local light, and a digital pulse intensity modulated signal is generated by optically / electrically converting the intensity modulated light. The electric signal obtained by superimposing the digital pulse intensity modulation signal is
Output from Then, this electric signal is amplified by the amplifier 9, converted into an optical signal by the transmission laser 10, and output to the optical branching / optical fiber transmission line.

As described above, according to the present embodiment, the multi-channel video signal is converted into a wideband FM signal and superimposed on the digital pulse signal, so that the multi-channel video signal and the digital pulse signal can be transmitted in a single transmission. It can be transmitted by the laser 10 for use.

In this embodiment, as shown in FIG. 8, two optical signals of the FM modulated light output from the FM modulated laser 2 and the local light output from the local laser 3 are converted by the optical coupler 4. After being multiplexed, the optical signal output from the optical coupler 4 and the intensity-modulated light output from the optical modulator 19 are multiplexed by the optical coupler 8.

However, according to the present invention, as shown in FIG. 9, two optical signals of the FM modulation light output from the FM modulation laser 2 and the intensity modulation light output from the optical modulator 19 are converted by the optical coupler 4. Even if the optical signal output from the optical coupler 4 and the local light output from the local laser 3 are multiplexed by the optical coupler 8 after the multiplexing, the same effect as that of the embodiment of FIG. Can be

Further, according to the present invention, as shown in FIG. 10, two optical signals of the intensity modulated light output from the optical modulator 19 and the local light output from the local laser 3 are multiplexed by the optical coupler 4. In addition, even when the optical signal output from the optical coupler 4 and the FM modulated light output from the FM modulation laser 2 are multiplexed by the optical coupler 8, the same effect as the embodiment of FIG. Can be

(Embodiment 3) FIG. 11 shows the configuration of a third embodiment of the optical transmission apparatus according to the present invention, wherein 1 is an input terminal to which a multi-channel video signal is input, and 2 is an oscillation terminal having a large oscillation frequency. F modulated by channel video signal
An FM modulation laser that outputs M-modulated light, 6 is an input terminal to which a digital pulse signal is input, and 20 is a digital signal whose FM modulation light output from the FM modulation laser 2 is intensity-modulated by a digital pulse signal input from the input terminal 6. An optical modulator that outputs FM modulated light, 3 is a local laser that outputs local light, and 4 is an optical coupler that outputs an optical signal obtained by combining the intensity-modulated FM modulated light and local light.

Reference numeral 5 denotes a broadband FM signal generated by heterodyne detection of the FM modulated light intensity modulated by the digital pulse signal and the local light, and an intensity modulation component of the FM modulated light intensity modulated by the digital pulse signal. / A light receiving element for outputting an electric signal superimposed with an electric converted digital pulse signal, 9 is an amplifier for amplifying the electric signal output from the light receiving element 5, and 10 is a transmission for converting the electric signal output from the amplifier 9 to an optical signal. Laser.

In the present embodiment configured as above, the oscillation frequency is FM-modulated by the multi-channel video signal input from the input terminal 1, and the FM-modulated light output from the FM-modulated laser 2 is output from the input terminal 6. After being intensity-modulated by the input digital pulse signal and output from the optical modulator 20, it is combined with the local light output from the local laser 3 and output from the optical coupler 4.

Then, the broadband FM signal obtained by heterodyne detection of the FM modulated light intensity modulated by the digital pulse signal and the local light and the intensity modulation component of the FM modulated light intensity modulated by the digital pulse signal are optically / electrically converted. When the electric signal on which the digital pulse signal is superimposed is output from the light receiving element 5, this electric signal is
The optical signal is amplified by the transmission laser 10 and converted into an optical signal by the transmission laser 10, and then output to the optical branching / optical fiber transmission line.

As described above, according to the present embodiment, a multi-channel video signal is converted into a wideband FM signal and superimposed on a digital pulse signal, so that the multi-channel video signal and the digital pulse signal are transmitted in a single signal. It can be transmitted by the laser 10 for use.

In the present embodiment, as shown in FIG. 11, the FM modulated light output from the FM
In the optical modulator 20, the intensity is modulated by the digital pulse signal input from the input terminal 6.

However, in the present invention, as shown in FIG. 12, the local light output from the local laser 3 is intensity-modulated in the optical modulator 20 by the digital pulse signal input to the input terminal 6. Thus, the same effect as in the embodiment of FIG. 11 can be obtained.

(Embodiment 4) FIG. 13 shows the configuration of an optical transmitter according to a fourth embodiment of the present invention, wherein 1 is an input terminal to which a multi-channel video signal is input, and 2 is a multi-oscillation frequency. F modulated by channel video signal
An FM modulation laser that outputs M-modulated light, 3 is a local laser that outputs local light, and 4 is an optical coupler that outputs an optical signal that combines the FM-modulated light and local light.

5 is a light receiving element for generating a broadband FM signal by heterodyne detection of the FM modulated light and local light, 21 is a high-pass filter for separating and outputting only the broadband FM signal, 6 is an input terminal for inputting a digital pulse signal, 22 is a low-pass filter that separates and outputs only the digital pulse signal, 23 is a multiplexer that combines the broadband FM signal output from the high-pass filter 21 and the digital pulse signal output from the low-pass filter 22, and 9 is a multiplexer. An amplifier 10 amplifies the broadband FM signal and the digital pulse signal multiplexed by the amplifier 23, and a transmission laser 10 converts the electric signal output from the amplifier 9 into an optical signal.

In the present embodiment configured as described above, the oscillation frequency is FM-modulated by the multi-channel video signal input from the input terminal 1 and the FM modulation light output from the FM modulation laser 2 and the local laser 3 The two optical signals with the output local light are multiplexed by the optical coupler 4.

Then, when the broadband FM signal is generated and output from the light receiving element 5 by heterodyne detection of the FM modulated light and the local light, only the high frequency band of the broadband FM signal is separated and output by the high-pass filter 21.
The digital pulse signal input from the input terminal 6 is separated and output only by a low-pass filter 22 in a low frequency band.

Then, the broadband FM signal output from the high-pass filter 21 and the digital pulse signal output from the low-pass filter 22 are multiplexed and superimposed by the multiplexer 23, but the pass frequency band of the high-pass filter 21 and the low-pass Since the pass frequency band of the filter 22 is different, even if the wideband FM signal and the digital pulse signal are combined, almost no loss occurs.

The electric signal output from the multiplexer 23 is amplified by the amplifier 9 and transmitted by the transmission laser 10.
The optical signal is converted to an optical signal and output to an optical branching / optical fiber transmission line.

As described above, according to the present embodiment, the multi-channel video signal is converted into a wideband FM signal and superimposed on the digital pulse signal, thereby transmitting the multi-channel video signal and the digital pulse signal in a single transmission. It can be transmitted by the laser 10 for use.

[0065]

As described above, according to the present invention,
By converting a multi-channel video signal into a wideband FM signal and superimposing it on a digital pulse signal, the multi-channel video signal and the digital pulse signal can be transmitted by a single transmission laser. This has the effect of reducing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining the principle of an optical transmission device according to the present invention.

FIG. 2 is a waveform diagram output from each block in FIG. 1;

FIG. 3 is a block diagram of an optical transmission device using the optical transmission device of the present invention.

FIG. 4 is a waveform diagram output from each block in FIG. 3;

FIG. 5 is a configuration diagram of an optical transmission device according to a first embodiment of the present invention.

FIG. 6 is another configuration diagram of the first embodiment in the optical transmission device of the present invention.

FIG. 7 is still another configuration diagram of the first embodiment in the optical transmission device of the present invention.

FIG. 8 is a configuration diagram of an optical transmission device according to a second embodiment of the present invention.

FIG. 9 is another configuration diagram of the optical transmission device according to the second embodiment of the present invention.

FIG. 10 is still another configuration diagram of the second embodiment of the optical transmission device of the present invention.

FIG. 11 is a configuration diagram of an optical transmission device according to a third embodiment of the present invention.

FIG. 12 is another configuration diagram of the third embodiment in the optical transmission device of the present invention.

FIG. 13 is a configuration diagram of a fourth embodiment of the optical transmitter according to the present invention.

FIG. 14 is a configuration diagram of a conventional optical transmission device.

FIG. 15 is a waveform diagram output from each block in FIG. 14;

[Explanation of symbols]

1, 6: input terminal, 2: FM modulation laser, 3: local laser, 4, 8: optical coupler, 5: light receiving element,
7: Digital signal laser, 9: Amplifier, 10: Transmission laser, 18: Laser, 19, 20: Optical modulator, 21: High-pass filter, 22: Low-pass filter, 23: Combiner.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04B 10/04 10/06 H04N 7/20

Claims (4)

[Claims] 1. An FM-modulated laser that outputs FM-modulated light whose oscillation frequency is FM-modulated by a multi-channel video signal input to an input terminal, a local laser that outputs local light, and a digital pulse signal input from an input terminal A digital pulse signal laser that outputs a digital intensity-modulated light obtained by intensity-modulating the light; a first light that outputs an optical signal obtained by combining any two of the FM-modulated light, the local light, and the intensity-modulated light A coupler, and multiplexes any one of the optical signal output from the first optical coupler, the FM modulated light, the local light, and the intensity modulated light that have not been multiplexed by the first optical coupler. A second optical coupler, a broadband FM signal is generated by heterodyne detection of the FM modulated light and the local light, and the intensity modulated light is optically / electrically converted to a digital pulse. A light receiving element that outputs an electric signal obtained by superimposing the broadband FM signal and the digital pulse intensity modulation signal after generating a degree modulation signal, an amplifier that amplifies the electric signal output from the light receiving element, and an output of the amplifier. A transmission laser for converting the converted electric signal into an optical signal, converting the multi-channel video signal into the broadband FM signal, and superimposing the multi-channel video signal and the digital pulse signal, thereby obtaining the multi-channel video signal. An optical transmission device, wherein a video signal and the digital pulse signal are transmitted by a single transmission laser. 2. An FM-modulated laser that outputs FM-modulated light whose oscillation frequency is FM-modulated by a multi-channel video signal input to an input terminal, a local laser that outputs local light, and a laser light output by the laser. An optical modulator that outputs digital intensity-modulated light that is intensity-modulated by a digital pulse signal input to a terminal; and an optical signal that combines any two of the FM-modulated light, the local light, and the intensity-modulated light. A first optical coupler to be output; any one of the FM signal, the local light, and the intensity-modulated light that has not been combined by the first optical coupler and the optical signal output by the first optical coupler. A second optical coupler that multiplexes one of the two, and a broadband FM signal is generated by heterodyne detection of the FM modulated light and the local light, and the intensity modulated light is optically / electrically converted. A light-receiving element that generates a digital pulse intensity modulation signal and outputs an electric signal obtained by superimposing the broadband FM signal and the digital pulse intensity modulation signal; an amplifier that amplifies the electric signal output from the light-receiving element; A transmission laser for converting the output electric signal into an optical signal; converting the multi-channel video signal into the broadband FM signal and superimposing the multi-channel video signal and the digital pulse signal, thereby obtaining the multi-channel video signal. An optical transmission device, wherein a channel image signal and the digital pulse signal are transmitted by a single transmission laser. 3. An FM-modulated laser that outputs FM-modulated light whose oscillation frequency is FM-modulated by a multi-channel video signal input to an input terminal, a local laser that outputs local light, and the FM-modulated light is input to an input terminal. Light for outputting any one of digital FM modulated light intensity-modulated by the input digital pulse signal and digital local light intensity-modulated by the digital pulse signal input to the input terminal of the local light. A modulator; an optical coupler for combining any one of the optical signal output from the optical modulator, the local light that has not been intensity-modulated by the optical modulator, and the FM modulated light; and the digital pulse signal. The F intensity modulated by
A broadband FM signal is generated by heterodyne detection of the M-modulated light or the local light and the local light or the FM-modulated light that has not been intensity-modulated, and the FM-modulated light or the local is intensity-modulated by the digital pulse signal. A light receiving element for generating a digital pulse signal by performing optical / electrical conversion of an intensity modulation component of light, and outputting an electric signal obtained by superimposing the broadband FM signal and the digital pulse signal; An amplifier for amplifying a signal; and a transmission laser for converting an electric signal output from the amplifier into an optical signal. The multi-channel video signal is converted to the broadband FM signal, and the multi-channel video signal and the digital pulse are converted. Signal and the digital pulse signal by superimposing the signals. Optical transmission apparatus characterized by transmitting a single said transmission laser. 4. An FM-modulated laser that outputs FM-modulated light whose oscillation frequency is FM-modulated by a multi-channel video signal input to an input terminal, a local laser that outputs local light, the FM-modulated light and the local light An optical coupler that outputs an optical signal obtained by multiplexing the above, a light receiving element that performs optical / electrical conversion of a broadband FM signal generated by heterodyne detection of the FM modulated light and the local light, and outputs an electric signal, A high-pass filter that passes the electric signal output from the light-receiving element, a low-pass filter that passes a digital pulse signal input to an input terminal, a broadband FM signal output from the high-pass filter, and a digital pulse signal output from the low-pass filter. And an amplifier for amplifying the electric signal output from the multiplexer. A transmission laser for converting the electric signal output from the amplifier into an optical signal, by converting the multi-channel video signal into the broadband FM signal and superimposing the multi-channel video signal and the digital pulse signal. An optical transmission apparatus for transmitting the multi-channel video signal and the digital pulse signal by a single transmission laser.