JPH10276138A - Optical transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the optical transmitter in which a circuit configuration of a power supply section to prevent destruction of a laser diode is simplified and an input signal (transmission data) received till the operation of the laser diode is stable is transmitted without lost its data. SOLUTION: An input signal detection circuit 12 detects a presence of an input signal. The input signal is given to a delay circuit 13, and its output is given to a modulation circuit 14. An output of the modulation circuit 14 is given to an electrooptic conversion circuit 15. When the input signal detection circuit 12 detects the presence of the input signal, a power switch is closed and the electrooptic conversion circuit 15 starts its operation. An output of the modulation circuit 14 corresponding to the input signal is given to the electrooptic conversion circuit 15 after the lapse of a time depending on the delay circuit 13 after the electrooptic conversion circuit 15 is in operation. When the input signal detection circuit detects absence of the input signal, the power switch 17 is open and the operation of the electrooptic conversion circuit 15 is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an optical transmitter in which a signal input is supplied to a laser diode after the operation of the laser diode is stabilized.

[0002]

2. Description of the Related Art In long-distance wired communication, an optical fiber line is more effective than a metal (that is, a twisted pair wire or a coaxial cable) in that the attenuation of the line is small. On the transmission side used for optical fiber communication, the input signal is either kept at baseband or modulated at an arbitrary frequency to generate an electrical / electrical signal typified by a laser diode.
The light is converted into light by an optical conversion element, and is input into an optical fiber line.In some cases, the attenuation in the optical fiber is amplified by an optical amplifier, and the light is transmitted through the optical fiber while correcting the dispersion. , Photo diode, etc.
It was converted to electricity by an electric conversion element and processed appropriately.

FIG. 13 is a diagram illustrating a laser diode. If there is no signal input, the laser diode L
A bias current supplied from the power supply Vcc flows through D.
When there is a signal input, a laser diode LD is supplied with a signal obtained by superimposing a signal input on a bias current. When the current flowing through the laser diode falls below a certain value, the output light of the laser diode LD becomes almost zero.

In a laser diode used on the transmitting side, when a signal is input to the laser diode without a bias current for driving the laser diode, a reverse bias is applied to the element, and the laser diode is destroyed. For example, control the power-on sequence in the device, wait for an arbitrary time after the power-on of the laser diode, allow signal input to the laser diode, or monitor the light-emitting level of the laser diode. When the level is not at an appropriate level, a method of cutting off the input to the laser diode has been used.

[0005] This will be described specifically with reference to FIG. When the power supply 96 is turned on, the power switch controller 95 turns off the power switch 93 and turns on the power switch 94.
Alternatively, the power switch 94 may not be provided. With the power switch 94 turned on, the laser diode therein begins to operate. After the laser diode operates sufficiently, the power switch 93 is turned on to operate the modulator 91, and outputs a modulation output to the electro-optical converter 92. In this way, no stress is applied to the laser diode.

Another conventional example will be described with reference to FIG. Power supply 10
When the switch 6 is turned on, the power is turned on to the modulator 101 and the electric / optical converter 105. The modulator 101 immediately starts the modulation output. Laser of electric / optical conversion device 105
The driver 108 has a delay function, and outputs the modulation output after the laser diode has sufficiently started emitting light.
Since the voltage is applied to the diode, no stress is applied to the laser diode even in this case.

[0007]

The conventional optical transmitter has a problem that the circuit configuration becomes complicated by the power switch controller for controlling the power switch as in the conventional example shown in FIG. . In the conventional example of FIG.
There is a problem that data input to the modulator cannot be transmitted until the laser diode enters a steady state after the power is turned on.

Further, in the conventional optical transmitter, the laser diode is protected when the power is turned on, but after the power is turned on, the laser diode operates continuously regardless of the presence or absence of an input signal. Even when there is no input, the laser diode is still operating, during which time the power does not make sense for signal transmission. In particular, DFB-LD among laser diodes
(Distributed feedback semiconductor lasers) and the like control the temperature of the laser diode itself, so that power consumption for controlling the temperature is large. For this reason, in a transmission device that operates on a storage battery or a solar cell, it is necessary to increase the capacity of the storage battery or the solar cell as a result. In addition, there is a problem that heat generation inside the apparatus is large particularly at a high temperature. Further, since the life of the laser diode is generally affected by the accumulated operation time, it is considered that the life of the laser diode is wasted for the time when there is no input signal.

The present invention has been made in view of this point, and is intended to input a signal to the electric / optical conversion circuit after the operation of the laser diode in the electric / optical conversion circuit is stabilized. An object of the present invention is to provide an optical transmitter capable of simplifying a circuit configuration. Another object of the present invention is to provide an optical transmitter in which transmission data input to the optical transmitter is not lost until the operation of the laser diode is stabilized. Another object of the present invention is to provide an optical transmitter with low power consumption. Still another object of the present invention is to provide an optical transmitter capable of extending the life of a laser diode.

[0010]

An outline of an optical transmitter according to the present invention will be described with reference to FIG. In the figure, 11 is a modulator, 12 is an input signal detection circuit, 13 is a delay circuit, 14
Is a modulation circuit, 15 is an electric / optical conversion circuit, 16 is a power supply, 1
Reference numeral 7 denotes a power switch. Modulation device 11
Are input signal detection circuit 12, delay circuit 13, modulation circuit 1
Four. The input signal detection circuit 12 detects the presence or absence of an input signal. The delay circuit 13 delays an input signal. The output of the delay circuit 13 is input to the modulation circuit 14. The output of the modulation circuit 14 is input to the electric / optical conversion circuit 15. The optical output of the electric / optical conversion circuit 15 is input to an optical fiber cable or the like. When the input signal detection circuit 12 detects the presence of an input signal, the power switch 17 is turned on, and power is supplied from the power supply 16 to the electric / optical conversion circuit 15. When the input signal detection circuit 12 detects no input signal, the power switch 17 is turned off,
The power supply from the power supply 16 to the electric / optical conversion circuit 15 is cut off. The modulator 11 is always supplied with power from a power supply 16.

The operation of the optical transmitter shown in FIG. 1 will be described.
The input signal detection circuit 12 outputs a signal to be transmitted (input signal).
Is detected. The transmitted signal is delayed by a predetermined time by the delay circuit 13 and is input to the modulation circuit 14.
The signal output from the modulation circuit 14 is a signal modulated from the baseband, and the modulation output is input to the electric / optical conversion circuit 15, converted into an optical output by the electric / optical conversion circuit 15, and transmitted by an optical fiber cable. Is done.

In the illustrated optical transmitter, power is always supplied to the input signal detection circuit 12, the delay circuit 13 and the modulation circuit 14, but the electric / optical conversion circuit 15 receives power from the input signal detection circuit 12. Power is supplied by the power switch 17 which is turned on / off in accordance with the value of the input signal determination output, in response to a signal input.

[0013]

FIG. 2 is a block diagram of a first embodiment of the present invention, and FIG. 3 is a diagram showing an example of a control signal generating circuit in the first embodiment of the present invention. 2 and 3,
21 is a modulation device, 22 is an input signal detection circuit, 23 is a memory circuit, 24 is a QPSK modulator, 25 is an electric / optical conversion circuit, 26 is an AC-DC converter, 27 is a power switch, 28 is an ATC / APC circuit, 29 is a laser diode, 210 is a control signal generation circuit, 211 is a delay circuit,
Reference numeral 212 denotes a logical sum circuit.

The modulation device 21 includes an input signal detection circuit 22,
It has a memory circuit 23 and a QPSK modulator 24. Input signal detection circuit 22 in modulation circuit 21, memory circuit 2
3, the QPSK modulation circuit 24 is always supplied with power from the AC-DC converter 26. The modulation device 21 includes
An input clock of 1.544 MHz and an input signal of 1.544 Mbps synchronized with this clock are input.
The input signal detection circuit 22 detects the presence or absence of an input signal.
When the input signal detection circuit 22 detects the presence of an input signal,
When the input signal determination output is turned on and the absence of the input signal is detected, the input signal determination output is turned off. Input signal detection circuit 2
2 is sent to the power switch 27 of the electric / optical conversion circuit 25 via the control signal generation circuit 210. Power is always supplied to the control signal generation circuit 210.

FIG. 3 is a diagram showing an example of the control signal generation circuit 210. The input signal determination output is input to the upper input terminal of the OR circuit 212 and to the input terminal of the delay circuit 211. The output of the delay circuit 211 is input to the lower input terminal of the OR circuit 212. Memory circuit 23
Operates as a delay circuit.
The delay time of 1 is longer than the delay time of the memory circuit 23.

The control signal generation circuit 210 outputs an ON signal immediately when the input signal judgment output is turned on, and outputs the ON signal immediately after the time determined by the delay time of the delay circuit 211 when the input signal judgment output is turned off. Outputs off signal. When the output of the control signal generation circuit 210 is turned on, the power switch 27 is turned on and the control signal generation circuit 21
When the output of 0 is turned off, the power switch 27 is turned off.

The input signal is input to an input signal detection circuit 22 and also to a memory circuit 23. As described above, the memory circuit 23 operates as a delay circuit, and is, for example, a shift register. Memory circuit 23
Is set to be longer than the time when the optical output (that is, the light emission level and the wavelength of light) of the laser diode 29 is stabilized after the power switch 27 is turned on.
This time is generally on the order of a few milliseconds. The output of the memory circuit 23 is input to the QPSK modulator 24. The QPSK modulator 24 does not output a high frequency when there is no input. The output of the QPSK modulator 24 is
The signal is input to the electric / optical modulation circuit 25.

The electric / optical conversion circuit 25 is supplied with power from the AC-DC converter 16 via a power switch 27. The electric / optical conversion circuit 25 has an ATC / APC circuit 28 and a laser diode 29. APC means an automatic light output control unit, and controls a bias current of the laser diode so that the light output becomes equal to a set value. ATC stands for Automatic Temperature Stabilizer,
Keep the temperature of the laser diode constant using a temperature sensor or Peltier device.

The operation of the first embodiment of the present invention will be described. When the input of the input signal to the input signal detection circuit 22 is started, the power switch 27 is turned on and the electric / optical conversion device 25 operates. When there is no input signal to the input signal detection circuit 22, after transmitting all the input data stored in the memory circuit 23, the power switch 27 is turned off and the operation of the electric / optical conversion circuit 25 is stopped.

FIG. 4 is a diagram showing a configuration example of an input signal detection circuit for digital signals used in the present invention. In the figure, 31 is an edge trigger circuit, 32 is an LC integration circuit, and 33 is a comparator. An input signal is input to the edge trigger circuit 31. When detecting the edge of the input signal, the edge trigger circuit 31 outputs a pulse. The output of the edge trigger circuit 31 is input to the LC integrator 32. The LC integration circuit 32 integrates the output of the edge trigger circuit 31. The output of the LC integration circuit 32 is input to the comparator 33. Comparator 3
Reference numeral 3 compares the output of the LC integration circuit 32 with the reference voltage Vref. If the former is greater than the latter, the input signal determination output is turned on, and if the former is less than the latter, the input signal determination output is turned off. In FIG. 4, the LC integrator 32 is used to integrate the output of the edge trigger circuit. Specifically, a known low-pass filter (low-pass filter, hereinafter abbreviated as LPF) using L, ie, a coil (inductor) and C, ie, a capacitor (capacitor), was used. This integrator is not limited to an integrator using an LC-type LPF, but may be a CR-type LPF using C and R (resistor) or another type of integrator. In particular, among those integrators,
The LC type LPF is suitable for a frequency of several MHz to several hundred MHz.

FIG. 5 is a diagram showing a signal waveform of each part of the input signal detection circuit. The input signal having the input signal waveform shown in FIG. 5 is input to the edge trigger circuit 31. The edge of FIG.
Like the trigger output waveform, a pulse is output when the input signal rises or falls. This pulse signal is input to the LC integration circuit 32 having an arbitrary time constant. When there is no input signal, the level of the input signal is High or Lo.
Since it is fixed to w and there is no change, the output of the LC integration circuit 32 becomes equal to or less than a certain threshold value (Vref). When there is a signal change, since there is an input signal, a pulse is output from the edge trigger circuit 31, so that the output of the LC integration circuit 32 becomes larger than a fixed threshold value Vref as shown in the integration circuit output waveform of FIG. Become. By determining the output of the LC integration circuit 32 by the comparator 33, the presence or absence of an input signal can be detected.

FIG. 6 shows an example of a power switch. As shown in FIG. 6, the power switch can be used by selecting a desired one from among relays, analog switches, transistor switches, and the like.

FIG. 7 is a block diagram of a second embodiment of the present invention.
FIG. 8 is a diagram showing an example of a control signal generation circuit according to the second embodiment of the present invention. 7 and 8, reference numeral 61 denotes a modulation device, 62 denotes an input signal detection circuit, 63 denotes a memory circuit,
64 is a QPSK modulator, 65 is an electric / optical conversion circuit, 66
Is an AC-DC converter, 67 is a power switch, 68 is an ATC / APC circuit, 69 is a laser diode, 61
1 is a control signal generation circuit, 612 is a power switch, 613
Also a control signal generation circuit, 614 and 615 are delay circuits, 61
Reference numeral 6 denotes an OR circuit, 617 denotes a delay circuit, and 618 denotes an OR circuit.

The modulation device 61 includes an input signal detection circuit 62,
It has a memory circuit 63 and a QPSK modulator 64. Input signal detection circuit 62 in modulation circuit 61, memory circuit 6
3 is always supplied with power from the AC-DC converter 66. The QPSK modulator 64 includes a power switch 6
Power is supplied from the AC-DC converter 66 via the power supply 12. The modulator 61 receives an input signal of 1.544 Mbps and an input clock of 1.544 MHz.

The input signal detection circuit 62 has a configuration as shown in FIG. 4 and detects the presence or absence of an input signal. The input signal detection circuit 62 turns on the input signal judgment output when detecting the presence of an input signal, and turns off the input signal judgment output when detecting no input signal. The input signal determination output from the input signal output circuit 62 is sent to the power switch 67 of the electric / optical conversion circuit 65 via the control signal generation circuit 613, and the power switch 61 via the control signal generation circuit 611.
Sent to 2. Power is always supplied to the control signal generation circuit 611 and the control signal generation circuit 613.

The control signal generation circuit 611 includes a delay circuit 61
4 and a delay circuit 615 and a logical sum circuit 616.
The input signal determination output is input to the delay circuit 614 and also to the delay circuit 615. The output of the delay circuit 614 is input to the upper input terminal of the OR circuit 616, and the output of the delay circuit 615 is input to the lower input terminal of the OR circuit 616. The output of the OR circuit 616 is the power switch 6
12 is a control signal.

The control signal generation circuit 613 includes a delay circuit 61
7 and an OR circuit 618. The input signal determination output is input to the upper input terminal of the OR circuit 618 and to the input terminal of the delay circuit 617. The output of the delay circuit 617 is input to the lower input terminal of the OR circuit 618. The output of the OR circuit 618 becomes a control signal to the power switch 67.

The delay time of the delay circuit 614 is T1, the delay time of the delay circuit 615 is T2, the delay time of the delay circuit 617 is T3, and the time from when the power switch 67 is turned on until the light output of the laser diode 69 stabilizes. The time of Ta,
Assuming that the delay time of the memory circuit 63 as a delay circuit is Tb, each delay time is set as Ta <T1 <Tb <T2 <T3.

As shown in FIG. 7, the input signal is input to an input signal detection circuit 62 and also to a memory circuit 63. The memory circuit 63 operates as a delay circuit, and is, for example, a shift register. The output of the memory circuit 63 is input to the QPSK modulator 64. QP
The SK modulator 64 outputs a high-frequency signal called an unmodulated carrier when there is no input. QPSK
The output of the modulator 64 is input to the electric / optical conversion circuit 65. The electric / optical conversion circuit 65 is supplied with power from an AC-DC converter 66 via a power switch 67.
The electric / optical conversion circuit 65 has an ATC / APC circuit 68 and a laser diode 69.

The operation of the second embodiment of the present invention will be described. When the input of the signal is started, the input signal detection circuit 6
2 is turned on, the power switch 6
7 is turned on, and the electrical / optical conversion circuit 65 starts operating.
After the light output of the laser diode 79 is stabilized, the power switch 612 is turned on, and the QPSK modulator 64 is operated. When there is no input signal, the memory circuit 63
Is turned off after all the input signals stored in the power supply switch are transmitted, the operation of the QPSK modulator 64 is stopped, then the power switch 67 is turned off, and the operation of the electric / optical conversion circuit 65 is stopped.

FIG. 9 is a block diagram of a third embodiment of the present invention. In the figure, 71 is a modulator, 72 is an input signal detection circuit, 73 is a memory circuit, 74 is a QPSK modulator,
75 is an electric / optical conversion circuit, 76 is an AC-DC converter, 77 is a power switch, 78 is an ATC / APC circuit,
79 is a laser diode, 710 is a high frequency switch,
Reference numerals 711 and 712 indicate control signal generation circuits, respectively.

The modulation device 71 includes an input signal detection circuit 72,
It has a memory circuit 73, a QPSK modulator 74, and a high-frequency switch 710. The input signal detection circuit 72, the memory circuit 73, and the QPSK modulation circuit 74 in the modulation circuit 71 are always supplied with power from the AC-DC converter 76. The modulator 71 receives an input signal of 1.544 Mbps and an input clock of 1.544 MHz.

The input signal detection circuit 72 has a configuration as shown in FIG. 4 and detects the presence or absence of an input signal. The input signal detection circuit 72 turns on the input signal judgment output when detecting the presence of an input signal, and turns off the input signal judgment output when detecting no input signal. The input signal determination output output from the input signal detection circuit 72 is sent to the power switch 77 of the electric / optical conversion circuit 75 via the control signal generation circuit 712 and to the high frequency switch 710 via the control signal generation circuit 711. Sent. Power is constantly supplied to the control signal generation circuit 711 and the control signal generation circuit 712.

The control signal generation circuit 712 has the same configuration as the control signal generation circuit 613 (see FIG. 8). When the input signal determination output is turned on, the power switch 77 is immediately turned on, and power is supplied to the electric / optical conversion circuit 75. When the input signal determination output is turned off, the power switch 77 is turned off T3 seconds after the input signal determination output is turned off, and the power supply to the electric / optical conversion circuit 75 is cut off.

The control signal generation circuit 711 has the same configuration as the control signal generation circuit 611 (see FIG. 8). When the input signal determination output is turned on, the control signal generation circuit 711 outputs an ON signal T1 seconds after the input signal determination output is turned on.
When the signal from control signal generation circuit 711 is on, high-frequency switch 710 is turned on and transmits the output of QPSK modulator 74 to electrical / optical conversion circuit 75. When the input signal determination output is turned off, the control signal generation circuit 711 outputs an off signal T2 seconds after the input signal determination output is turned off. The high-frequency switch 710 is connected to the control signal generation circuit 7
When the signal from 11 is off, it becomes non-conductive,
The transmission of the output of the QPSK modulator 74 to the electric / optical conversion circuit 75 is cut off.

The input signal is input to the input signal detection circuit 72 and also to the memory circuit 73. The memory circuit 73 operates as a delay circuit, and is, for example, a shift register. The output of the memory circuit 73 is Q
The signal is input to the PSK modulator 74. QPSK modulator 74
Outputs a high-frequency signal called an unmodulated carrier when there is no input. The output of the QPSK modulator 74 is input to the electric / optical conversion circuit 75 via the high frequency switch 710. The electric / optical conversion circuit 75 is supplied with power from an AC-DC converter 76 via a power switch 77. The electric / optical conversion circuit 75 is an ATC / AP
It has a C circuit 78 and a laser diode 79.

The operation of the third embodiment of the present invention will be described. When the input of the signal is started, the power switch 77 is immediately turned on, and the electric / optical conversion circuit 75 is operated. After the light output of the laser diode 79 is stabilized, the high-frequency switch 710 is turned on. When there is no input signal, the high-frequency switch 710 is turned off after all the input data stored in the memory circuit 73 has been transmitted, then the power switch 77 is turned off, and the operation of the electric / optical conversion circuit 75 is stopped. .

FIG. 10 is a block diagram of a fourth embodiment of the present invention. In the figure, 81 is a modulation device, 82 is an input signal detection circuit, 83 is a memory circuit, 84 is a QPSK modulator, 85 is an electric / optical conversion circuit, 86 is an AC-DC converter, 87 is an LD bias current switch, 88 Is ATC
/ APC circuit, 89 indicates a laser diode, 810 indicates a high-frequency switch, and 811 and 812 indicate control signal generation circuits.

The modulation device 81 includes an input signal detection circuit 82,
It has a memory circuit 83, a QPSK modulator 84, and a high-frequency switch 810. Power is always supplied from an AC-DC converter 86 to the input signal detection circuit 82, the memory circuit 83, and the QPSK modulation circuit 84 in the modulation device 81. The modulator 81 receives an input signal of 1.544 Mbps and an input clock of 1.544 MHz.

The input signal detection circuit 82 has a configuration as shown in FIG. 4 and detects the presence or absence of an input signal. The input signal detection circuit 82 turns on the input signal judgment output when detecting the presence of an input signal, and turns off the input signal judgment output when detecting no input signal. The input signal determination output output from the input signal detection circuit 82 is sent to the LD bias current switch 87 via the control signal generation circuit 812, and
High frequency switch 810 via control signal generation circuit 811
Sent to Power is constantly supplied to the control signal generation circuit 811 and the control signal generation circuit 812.

The control signal generation circuit 812 has the same configuration as the control signal generation circuit 613 (see FIG. 8). When the input signal determination output is turned on, the LD bias current switch 87 is immediately turned on, and a bias current is supplied to the laser diode 89. When the input signal determination output is turned off, the LD bias current switch 87 is turned off and the bias current of the laser diode 89 is turned off T3 seconds after the input signal judgment output is turned off.

The control signal generation circuit 811 has the same configuration as the control signal generation circuit 611 (see FIG. 8). When the input signal determination output is turned on, the control signal generation circuit 811 outputs an ON signal T1 seconds after the input signal determination output is turned on.
When the signal from control signal generation circuit 811 is on, high-frequency switch 810 is turned on and transmits the output of QPSK modulator 84 to electrical / optical conversion circuit 85. When the input signal determination output is turned off, the control signal generation circuit 811 outputs an off signal T2 seconds after the input signal determination output is turned off. The high-frequency switch 810 includes the control signal generation circuit 8
When the signal from 11 is off, it becomes non-conductive,
The transmission of the output of the QPSK modulator 84 to the electric / optical conversion circuit 85 is cut off.

The input signal is input to an input signal detection circuit 82 and also to a memory circuit 83. The memory circuit 83 operates as a delay circuit, and is, for example, a shift register. The output of the memory circuit 83 is Q
The signal is input to the PSK modulator 84. QPSK modulator 84
Outputs a high-frequency signal called an unmodulated carrier when there is no input. The output of the QPSK modulator 84 is input to the electric / optical conversion circuit 85 via the high frequency switch 810. The electric / optical conversion circuit 85 uses an ATC /
An APC circuit 88 and a laser diode 89 are provided. The electric / optical conversion circuit 85 is always supplied with power from an AC-DC converter 86 (not shown), but the bias current flowing through the laser diode is substantially zero when the LD bias current switch 87 is turned off. become.

The operation of the fourth embodiment of the present invention will be described. When the input signal detection circuit 82 determines that there is no input signal, the LD bias current switch 87 is turned off by the OFF input signal determination output output from the input signal detection circuit 82, and the electric / optical conversion circuit 85 is turned off. ATC /
The laser diode 8 is used as a reference voltage for the APC circuit 88.
The bias current of No. 9 is turned off. Further, the input signal determination output of OFF is applied to the high-frequency switch 810 via the control signal generation circuit 811 to cut off the unmodulated carrier output from the QPSK modulator 84.

Next, when the input of a signal is started, first, the LD bias current switch 87 is turned on, and the bias current flowing through the laser diode 89 is set to a value in a normal communication state. After delaying the ON input signal determination output from the input signal detection circuit 82 by the optical output stabilization time of the laser diode 89, the ON output is applied to the high frequency switch 810 to make the high frequency switch 810 conductive.

[0046]

As is apparent from the above description, according to the present invention, it is possible to simplify the circuit configuration of the power supply unit while maintaining the effect of not destroying the laser diode in the optical transmitter. Further, according to the present invention, since the delay circuit is provided, the data input during the time until the laser diode stably operates can be transmitted without being lost.

Further, according to the present invention, when a high-frequency switch is provided in the subsequent stage of the modulator, a power switch becomes unnecessary, so that a relay having mechanical contacts or power loss due to a voltage drop occurs. No semiconductor switch is required. Further, according to the present invention, power consumption in an electric / optical conversion circuit such as a laser diode can be reduced.
It is possible to reduce the capacity of storage batteries, solar cells, and the like. Further, according to the present invention, the operation of the laser diode is discontinued, so that the life of the laser diode can be extended. Further, according to the present invention, it is possible to transmit data stored in the delay circuit when there is no input signal.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an outline of the present invention.

FIG. 2 is a block diagram of a first embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a control signal generation circuit according to the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration example of an input signal detection circuit.

FIG. 5 is a diagram showing a signal waveform of each part of the input signal detection circuit.

FIG. 6 is a diagram illustrating an example of a power switch.

FIG. 7 is a block diagram of a second embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of a control signal generation circuit according to a second embodiment of the present invention.

FIG. 9 is a block diagram of a third embodiment of the present invention.

FIG. 10 is a block diagram of a fourth embodiment of the present invention.

FIG. 11 is a block diagram of a conventional example.

FIG. 12 is a block diagram of another conventional example.

FIG. 13 is a diagram illustrating a laser diode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Modulator 12 Input signal detection circuit 13 Delay circuit 14 Modulation circuit 15 Electric / optical conversion circuit 16 Power supply 17 Power switch 21 Modulator 22 Input signal detection circuit 23 Memory circuit 24 QPSK modulator 25 Electric / optical conversion circuit 26 AC-DC Converter 27 Power switch 28 ATC / APC circuit 29 Laser diode 31 Edge trigger circuit 32 LC integration circuit 33 Comparator 61 Modulator 62 Input signal detection circuit 63 Memory circuit 64 QPSK modulator 65 Electric / optical conversion circuit 66 AC-DC converter 67 Power switch 68 ATC / APC circuit 69 Laser diode 611 Control signal generation circuit 612 Power switch 71 Modulator 72 Input signal detection circuit 73 Memory circuit 74 QPSK modulator 75 Electric / optical conversion circuit 76 C-DC converter 77 Power switch 78 ATC / APC circuit 79 Laser diode 710 High frequency switch 711 Control signal generation circuit 81 Modulator 82 Input signal detection circuit 83 Memory circuit 84 QPSK modulator 85 Electric / optical conversion circuit 86 AC-DC converter 87 LD bias current switch 88 ATC / APC circuit 89 Laser diode 810 High frequency switch 811 Control signal generation circuit

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI H01S 3/096

Claims (4)

[Claims] 1. An input signal detection circuit for detecting the presence or absence of an input signal, a delay circuit for delaying an input signal, a modulator for modulating an output of the delay circuit, and an electric signal output from the modulator being converted into an optical signal. A power switch for the electrical / optical conversion circuit; and a power switch for the electrical / optical conversion circuit. If the input signal detection circuit determines that there is no input signal, the power switch for the electrical / optical conversion circuit is turned on. By shutting off, the operation of the electric / optical conversion circuit is stopped, and when the input signal detection circuit determines that the input of the input signal has started, the power switch for the electric / optical conversion circuit is turned on. And an optical transmitter. 2. An input signal detection circuit for detecting the presence or absence of an input signal, a delay circuit for delaying an input signal, a modulator for modulating an output of the delay circuit, and an electric signal output from the modulator being converted into an optical signal. A power switch for the modulator, a power switch for the modulator, and a power switch for the electrical / optical converter. If the input signal detection circuit determines that there is no input signal, a power supply for the modulator is provided. To stop the operation of the modulator, and then shut off the power switch for the electric / optical conversion circuit to stop the operation of the electric / optical conversion circuit. The input signal detection circuit starts input of the input signal. An optical transmitter, characterized in that when it is determined that the power is turned on, the power switch of the electric / optical conversion circuit is turned on to operate the electric / optical conversion circuit, and thereafter the power switch for the modulator is turned on. 3. An input signal detection circuit for detecting the presence or absence of an input signal, a delay circuit for delaying the input signal, a modulator for modulating the output of the delay circuit, a high-frequency output cutoff switch, and a high-frequency output cutoff switch. If the input signal detection circuit determines that there is no input signal, it has an electrical / optical conversion circuit for converting the modulator output sent to the optical signal into an optical signal, and a power switch for the electrical / optical conversion circuit. If the power supply switch for the electrical / optical conversion circuit is turned off to stop the operation of the electrical / optical conversion circuit, and the input signal detection circuit determines that the input of the input signal has been started, the electrical / optical conversion circuit An optical transmitter characterized in that an electric / optical conversion circuit is operated by turning on a power switch for power supply, and then a high-frequency output cutoff switch is turned on. 4. An input signal detection circuit, a delay circuit for delaying an input signal, a modulator for modulating an output of the delay circuit, a high-frequency output cutoff switch, and a modulator sent via the high-frequency output cutoff switch It has an electric / optical conversion circuit for converting the output into an optical signal, and a laser diode bias current switch for the electric / optical conversion circuit. If the input signal detection circuit determines that there is no input signal, the laser・ Automatic optical output control in electric / optical conversion circuit by turning off diode / bias current switch /
Controls the automatic temperature control circuit to stop the operation of the laser diode. If the input signal detection circuit determines that the input of the input signal has started, the laser diode bias current switch for the electric / optical conversion circuit An optical transmitter for controlling the automatic optical output control / automatic temperature control circuit of the electric / optical conversion circuit to operate the laser diode, and thereafter conducting the high frequency output cutoff switch.