JP2004253987A - Optical transmitter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmitter capable of avoiding local concentration of heat and of performing stable operation in converting transmission data into an optical signal and transmitting it. <P>SOLUTION: The transmitter is equipped with a plurality of light emitters LD (Laser Diode) 1 to LDn which are provided in common to the identical transmission data and have an output side connected to a single waveguide 3, a sequential light emission control means 4 for performing sequential light emission control with the light emitters LD1 to LDn one by one, and outputting the transmission data as the optical signal into the waveguide 3. By reusing the plurality of light emitters LD1 to LDn by switching them one by one and emitting light to the identical transmission data, it is possible to avoid the topical concentration of heat as in the case of a single light emitter. Also, by enlarging a heating area even more, larger thermal conductance between the light emitters and a cooling mechanism can be taken and heat dissipation becomes easy. As operating temperatures of the light emitters LD1 to LDn fall, the operation becomes more stable. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical transmitter used in the field of optical communication or optical connection capable of coping with high speed based on an ultra-miniaturization process accompanying high integration of LSI, for example.
[0002]
[Prior art]
In recent years, with the speeding up of a computer environment including information processing, a display, a printer, and the like, a high-speed LSI or a high-speed MPU has been developed. The speedup based on the ultra-miniaturization process accompanying such high integration has led to a rapid increase in power density, and due to the problem of heat generation and heat dissipation, it is no longer necessary to expect stable operation if it is proceeded as it is. Is falling into. In particular, it is clear that the limitations of the current electric wiring will be seen in the near future.
[0003]
For this reason, connection using light having higher throughput (high-speed transfer capability) (optical communication or optical connection) = optical interconnection technology has attracted attention (for example, see Patent Document 1). This optical interconnection converts an electrical signal from an IC or the like into E (electricity) / O (light), and converts the converted optical signal to another IC or board through an optical wiring (such as an optical waveguide) formed in the board. , And then O / E converted to an electrical signal to exchange signals.
[0004]
[Patent Document 1]
JP 2001-36197 A
[0005]
[Problems to be solved by the invention]
However, in the case of such an optical connection, heat generated by an LD (laser diode) as a light source and a driver for driving the light source further exacerbates the situation, and requires some care. That is, the amount of heat generated by the high integration becomes more and more remarkable with the introduction of such an optical connection. Heat dissipation from the air has become a major problem.
[0006]
For example, in the conventional optical connection or optical communication, only one LD is used for a single data string. Therefore, with an increase in speed, the LD drivers disposed immediately close to the LD continue to operate without break. Therefore, the concentration of heat around the LD becomes large. When heat is concentrated on such a small area, the conductance between the heat radiator and the heat radiator is limited because the contact area is small, and a situation where heat radiation is difficult is created. In particular, an LD suitable as a light emitting element is extremely sensitive to the influence of heat, and the surrounding electronic circuits are similarly affected. Measures are being sought to avoid excessive concentration.
[0007]
An object of the present invention is to provide an optical transmitter capable of avoiding local concentration of heat and performing stable operation when transmitting transmission data after converting it into an optical signal.
[0008]
[Means for Solving the Problems]
An optical transmitter according to claim 1, wherein a plurality of light emitting elements which are provided in common for the same transmission data and whose output side is connected to a single waveguide, and each light emitting element among these light emitting elements And a sequential light emission control means for sequentially controlling light emission to output the transmission data as an optical signal into the waveguide.
[0009]
Therefore, by selectively switching a plurality of light emitting elements sequentially for the same transmission data to emit light, a plurality of light emitting elements can be reused, so that heat is not locally applied as in the case of a single light emitting element. Concentration can be avoided, and the heat generation can be facilitated by enlarging the heat generation area and increasing the thermal conductance between the cooling mechanism. The operation becomes stable as the operating temperature of the light emitting element decreases.
[0010]
According to a second aspect of the present invention, in the optical transmitter according to the first aspect, the light emitting element is a laser diode.
[0011]
Therefore, the configuration is suitable for optical communication.
[0012]
According to a third aspect of the present invention, in the optical transmitter according to the second aspect, the laser diode is a surface emitting semiconductor laser (VCSEL).
[0013]
Therefore, by using a surface emitting semiconductor laser (VCSEL), the arrangement and wiring of the light emitting elements are facilitated, and the arraying thereof is also facilitated.
[0014]
According to a fourth aspect of the present invention, in the optical transmitter according to any one of the first to third aspects, the sequential light emission control unit controls each light emitting element at a constant time period in accordance with an input of a data string as the transmission data. Are sequentially controlled.
[0015]
Therefore, by sequentially switching the plurality of light emitting elements at a constant time period, the amount of heat generated per unit area can be reduced, and the system can be stabilized, so that higher speed and higher reliability can be obtained. .
[0016]
According to a fifth aspect of the present invention, in the optical transmitter according to any one of the first to third aspects, the sequential light emission control means sequentially emits light from each light emitting element in synchronization with a modulation of a data string as the transmission data. Control.
[0017]
Therefore, by sequentially controlling the light emission of each light emitting element in synchronization with the modulation of the data string that is the transmission data, it is possible to control the switching timing to be changed in accordance with the data amount and the like. Control can be performed, heat generation can be made uniform, the system can be further stabilized, and higher speed and higher reliability can be obtained.
[0018]
According to a sixth aspect of the present invention, in the optical transmitter according to any one of the first to third aspects, the sequential light emission control means includes a light emitting element for each packet for the packet data which is the transmission data. Are sequentially controlled.
[0019]
Therefore, by controlling the light emitting elements that sequentially emit light for each packet, which is the most basic unit of the transmission data, a time margin can be easily obtained between packets, so that an appropriate switching time can be set, and the sequential emission control means can be controlled. The requirement for high-speed operation can be reduced, which is advantageous in cost.
[0020]
According to a seventh aspect of the present invention, in the optical transmitter according to any one of the first to sixth aspects, the light emitting elements are arranged and arranged, and the sequential light emission control means sets the order in which each light emitting element emits light one by one. Discontinuous between adjacent light emitting elements.
[0021]
Therefore, when the light emitting elements arranged in a line are simply emitted sequentially, the influence of the heat of the light emitting element itself and the light emitting elements emitting light at the preceding and following timings is continuously received, and the switching speed of the light emitting element control means is sequentially changed. Is slow, there is a possibility that the temperature of the light emitting portion rises excessively. However, the order in which light is sequentially emitted is set to be discontinuous between adjacent light emitting elements, such as every other light emitting element. Thereby, the local heat concentration can be reduced, and the heat generation distribution of the plurality of light emitting elements can be equalized. Therefore, the demand for the high speed operation of the light emission control means can be reduced sequentially, which is advantageous in cost. Become.
[0022]
According to an eighth aspect of the present invention, in the optical transmitter according to any one of the first to sixth aspects, the sequential light emission control unit sets the order in which each light emitting element emits light sequentially based on a random number.
[0023]
Therefore, if the control of the light emitting order is skipped, it may be difficult to equalize the heat generation distribution for a plurality of light emitting elements depending on the case where the number of light emitting elements is fractional or the regular light emitting order. By randomly controlling the light emission order based on the above, it is possible to equalize the heat generation distribution of the plurality of light emitting elements in a long term.
[0024]
According to a ninth aspect of the present invention, in the optical transmitter according to any one of the first to eighth aspects, the optical transmitter includes a failure detecting unit that detects a failed light emitting element among the light emitting elements, and the sequential light emission control unit includes a failure detecting unit. If the detected light emitting element is detected by the failure detecting means, the light emitting order is changed to the light emitting element scheduled to emit light next to the light emitting element.
[0025]
Accordingly, when a failure occurs in a plurality of light emitting elements, the failure light emitting element is skipped, and the light emitting order is changed so that the next light emitting element to be lighted emits light, thereby not being affected by the failure. Stable optical communication becomes possible.
[0026]
According to a tenth aspect of the present invention, in the optical transmitter according to any one of the first to seventh aspects, the optical transmitter further includes a failure detecting unit that detects a failed light emitting element among the light emitting elements, and the sequential light emission control unit includes a failure detecting unit. When the failed light emitting element is detected by the failure detecting means, the light emission control is sequentially redefined for the remaining light emitting elements except the light emitting element.
[0027]
Therefore, when a failure occurs in a plurality of light-emitting elements, basically, the light-emitting element may be skipped to emit light, but, for example, an adjacent light-emitting element continuously fails and the like. However, if there is a specific failure light emitting element existence pattern, there is a concern that optimal heat distribution may not be achieved. By optimizing the dispersion, stable operation can be continued.
[0028]
According to an eleventh aspect of the present invention, in the optical transmitter according to the eighth aspect, the optical transmitter further comprises failure detection means for detecting a failed light emitting element among the light emitting elements, and the sequential light emission control means includes: If detected by the detecting means, a random number is generated for the remaining light emitting elements except the light emitting element, and the order in which the light emitting elements sequentially emit light is random based on the random number.
[0029]
Therefore, when a failure occurs in a plurality of light-emitting elements, basically, the light-emitting element may be skipped to emit light, but, for example, an adjacent light-emitting element continuously fails and the like. If there is a specific failure light emitting element existing pattern, there is a concern that optimal heat distribution may not be achieved.However, a random number is generated for surviving light emitting elements excluding the failed light emitting element, and each light emitting element is generated based on the random number. By making the order in which the light-emitting elements emit light randomly, even if the number of light-emitting elements is reduced, the optimization of the heat dispersion can be maintained, and the stable operation can be continued.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic block diagram illustrating a configuration example of the optical transmitter according to the present embodiment. The optical transmitter according to the present embodiment converts an electric signal from a memory (storage element) such as a highly integrated LSI or MPU into E (electric) / O (light), and converts the converted optical signal to a board. It is used for transmitting signals to other LSIs or MPUs through optical wirings (optical waveguides etc.) formed inside, and then performing O / E conversion to return to electrical signals for exchanging signals. is there.
[0031]
This optical transmitter accepts, as transmission data, a data sequence in which binary data output from a storage element (not shown) are arranged on a time axis, for example. , LDn, which are the light emitting elements, are arranged one-dimensionally. Here, a surface emitting semiconductor laser (VCSEL) is used as the laser diodes LD1, LD2,..., LDn. The LD array 1 is formed by integrating these laser diodes LD1, LD2,..., LDn together with the corresponding drivers D1, D2,..., Dn on the same substrate (not shown). This substrate is a substrate having good heat conductivity, and is provided with a heat radiation mechanism (cooling mechanism) as necessary. In particular, by using a surface emitting semiconductor laser (VCSEL), arrangement and wiring of light emitting elements are facilitated, and arraying thereof is also easy. The laser diodes LD1, LD2,..., LDn are one-dimensionally arranged, but may be two-dimensionally arranged in some cases.
[0032]
The output side of such an LD array 1 is connected via a beam combiner 2 to a single waveguide 3 such as an optical fiber. On the other hand, the input side of the LD array 1 is connected to a multiplexer 4 as sequential light emission control means for sequentially and selectively controlling the light emission of each of the laser diodes LD1, LD2,. The multiplexer 4 is connected to a timer 5 that counts clocks of an input data string, and is configured to perform sequential light emission control by the multiplexer 4 at regular time intervals, for example, every 1 msec.
[0033]
In such a configuration, when a data string based on binary data is input to the optical transmitter, the laser diode LD emits light in accordance with the data of the data string, and is converted into an optical signal and communicated through the waveguide 3. However, a plurality of laser diodes LD1, LD2,..., LDn are provided in common for the same data string, and under control of the timer 5, the multiplexer 4 controls the laser every 1 msec. The laser diodes to emit light are selectively switched from one of the diodes LD1, LD2,..., LDn. For example, emission control is performed every 1 msec in the order of laser diodes LD1, LD2,..., LDn. Then, the selected laser diode flashes and emits light according to the data in the data string. Whichever laser diode emits light, it is optically coupled to a single waveguide 3 by the beam combiner 2 and output.
[0034]
That is, as described above, in the conventional optical connection or optical communication, only one LD is used for a single data string, and therefore, as the speed is increased, the LD driver arranged immediately close to the LD is used. Since the operation is continued without a break, the concentration of heat around the LD becomes large. When heat is concentrated on such a small area, the conductance between the heat radiator and the heat radiator is limited because the contact area is small, and a situation where heat radiation is difficult is created. In particular, an LD suitable as a light emitting element is extremely sensitive to the influence of heat, and the surrounding electronic circuits are similarly affected. Measures are being sought to avoid excessive concentration. In this regard, according to the present embodiment, laser diodes LD1, LD2,..., LDn are assigned as a plurality of light emitting elements to a single data string so that light is emitted selectively in a fixed time cycle. By sequentially controlling light emission, the amount of heat generated per unit area on the substrate can be reduced, the optical communication system can be stabilized, and higher speed and higher reliability can be obtained. That is, by using the plurality of laser diodes LD1, LD2,..., LDn repeatedly, it is possible to avoid concentration of heat in a local area as in the case of a single laser diode, and to increase the heat generation area to cool down. Heat dissipation is facilitated by increasing the thermal conductance with the mechanism. The operation becomes stable as the operating temperature of the laser diodes LD1, LD2,..., LDn decreases.
[0035]
A second embodiment of the present invention will be described with reference to FIG. The same portions as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted (the same applies to each of the following embodiments).
[0036]
Basically, it is the same as in the first embodiment, except that the multiplexer 4 is provided with a counter 6 for counting the number of data in the data sequence instead of the timer 5, so that the number of data can be reduced. That is, the light emission control of the laser diodes LD1, LD2,..., LDn is sequentially performed by the multiplexer 4 in synchronization with the modulation of the data string that is the transmission data.
[0037]
According to the present embodiment, it is possible to control to change the switching timing according to the data amount or the like, as compared with the case where the switching control is performed in a fixed time cycle, and it is possible to perform the control according to the use situation. And uniform heat generation can be achieved. Therefore, the system can be further stabilized, and higher speed and higher reliability can be obtained.
[0038]
A third embodiment of the present invention will be described with reference to FIG. Basically, it is the same as in the first and second embodiments, but pays attention to data in packet units as transmission data, and outputs the laser diodes LD1, LD2,. , LDn are sequentially controlled.
[0039]
That is, in the present embodiment, before extracting and transmitting the header information of the packet, the switching signal of the laser diodes LD1, LD2,. Light emission is sequentially switched.
[0040]
According to the present embodiment, the laser diodes LD1, LD2,..., LDn are switched for each packet, which is the most basic unit of information, so that it is easy to obtain a time margin between packets. As a result, it is possible to reduce the demand for high-speed operation of the multiplexer 4, which is advantageous in terms of cost.
[0041]
A fourth embodiment of the present invention will be described with reference to FIG. This embodiment relates to the order in which the laser diodes LD1, LD2,..., LDn arranged in order are sequentially emitted by the multiplexer 4, and is applicable to any of the first to third embodiments. .
[0042]
In the above-described embodiment, when the multiplexer 4 is operated at high speed and the laser diodes LD1, LD2,..., LDn are frequently switched, the heat in the LD array 1 is uniformly dispersed. However, high-speed multiplexers are expensive and consume high power. Therefore, it is preferable that the operation of the multiplexer be as slow as possible. For this reason, in the present embodiment, the emission order of the laser diodes LD1, LD2,..., LDn is controlled so that the heat generation distribution in the LD array 1 can be equalized.
[0043]
This point will be described with reference to the explanatory diagram shown in FIG. In the above-described embodiment, for example, eight laser diodes arranged in one line are sequentially emitted as shown in FIG. 4A in the order of 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8. In this case, the temperature of the laser diode is continuously affected by the heat of the immediately preceding laser diode, the heat of the laser diode itself, and the heat of the immediately succeeding laser diode. In this case, if the switching speed of the multiplexer 4 is low, the temperature of the light emitting portion may increase excessively.
[0044]
In this regard, in this embodiment, as shown in FIG. 4B, for example, eight laser diodes are arranged one by one such as 1 → 5 → 2 → 6 → 3 → 7 → 4 → 8. Alternatively, as shown in FIG. 4C, for example, ten laser diodes are adjacent to each other in the order of two, such as 1 → 5 → 8 → 2 → 6 → 9 → 3 → 7 → 10 → 4. The order is such that the laser diodes become discontinuous.
[0045]
In this way, by sequentially setting the order of light emission so as to be discontinuous between adjacent laser diodes one by one, and so on, every two laser diodes LD1 can reduce the local concentration of heat and reduce the number of laser diodes LD1. , LD2,..., LDn. Therefore, the requirement for the high-speed operation of the multiplexer 4 can be eased, which is advantageous in terms of cost.
[0046]
A fifth embodiment of the present invention will be described with reference to FIG. This embodiment also relates to the order when the laser diodes LD1, LD2,..., LDn are sequentially emitted by the multiplexer 4, and is applicable to any of the first to third embodiments.
[0047]
In the present embodiment, a random number generator 7 for generating a random number relating to the order in which light is sequentially emitted from the multiplexer 4 is added, and the order in which the laser diodes LD1, LD2,. Is controlled. In this case, the input transmission data may be a data string or data in packet units.
[0048]
As in the fourth embodiment, if the control of the light emission order is skipped, a plurality of laser diodes may be generated, such as a case where the number of laser diodes is fractional or a specific heat distribution pattern occurs depending on the regular light emission order. In some cases, it is difficult to equalize the heat generation distribution with respect to the laser diodes. However, as in the present embodiment, by controlling the light emission order randomly based on random numbers, each laser diode emits light with the same probability as in the Monte Carlo simulation. Therefore, it is possible to equalize the heat distribution of the plurality of laser diodes in a long term.
[0049]
A sixth embodiment of the present invention will be described with reference to FIG. In the above-described embodiment, the case where any one of the laser diodes LD1, LD2,..., LDn in the LD array 1 fails (including deterioration) is not taken into consideration. This takes into account the case of failure.
[0050]
That is, in each of the above-described embodiments, if a failure occurs, such as deterioration of the performance of any one of the laser diodes LD1, LD2,... In this case, the optical communication is shared and the functions of the entire system cannot be fulfilled at all. In particular, as the number of laser diodes constituting the LD array 1 increases, the risk increases.
[0051]
Therefore, in the present embodiment, a failure detection unit (failure detection means) 8 for detecting the presence of a failed laser diode in the laser diodes LD1, LD2,..., LDn is added. For example, the failure detecting unit 8 monitors a detection output from a PD (photodiode) incorporated in the LD array 1 and used for APC (automatic output adjustment) for each laser diode to detect a failed laser diode. The configuration may be specified and stored. When the failure detector 8 detects a failed laser diode LDi in the laser diodes LD1, LD2,..., LDn, the multiplexer 4 emits light so that the laser diode to be emitted next to the laser diode LDi emits light. To change.
[0052]
Therefore, according to the present embodiment, when a failure occurs in the plurality of laser diodes LD1, LD2,..., LDn, the failed laser diode LDi is skipped, and the laser diode to be lit next emits light. By changing the light emission order in this way, stable optical communication that is not affected by a failure can be performed.
[0053]
Although the illustrated example has been described as an example applied to the first embodiment described with reference to FIG. 1, the present invention can be similarly applied to the second to fourth embodiments.
[0054]
A seventh embodiment of the present invention will be described. In the present embodiment, in the configuration of the sixth embodiment, when the laser diode LDi that has failed in the laser diodes LD1, LD2,..., LDn is detected by the failure detection unit 8, the laser diode LDi is excluded. The sequential emission control is redefined by the multiplexer 4 with respect to the remaining normal laser diodes, and the emission control is sequentially performed according to the redefinition.
[0055]
That is, when a failure occurs in the plurality of laser diodes LD1, LD2,..., LDn, basically, the laser diode LDi that has failed can be skipped to emit light. If (i + 1) continues to cause a failure or the like, and there is a specific failure laser diode existence pattern, there is a concern that optimal heat distribution may not be achieved. In this regard, according to the present embodiment, by continuously redefining the emission control again in order by using the normal laser diode that has survived except for the failed laser diode and optimizing the heat dispersion, it is possible to continue the operation. Stable operation can be continued.
[0056]
An eighth embodiment of the present invention will be described with reference to FIG. This embodiment is based on the fourth embodiment, and when a failure detecting unit 8 detects a failed laser diode LDi in the laser diodes LD1, LD2,. Random numbers are generated by the random number generator 7 for the remaining normal laser diodes, and the order in which the remaining normal laser diodes sequentially emit light is random based on the random numbers.
[0057]
That is, when a failed laser diode LDi occurs in the plurality of laser diodes LD1, LD2,..., LDn, basically, the laser diode LDi may be skipped to emit light. If the existence pattern of the specific failed laser diode occurs due to the failure of the diode LD (i + 1) continuously, there is a concern that optimal heat distribution may not be achieved. In this regard, in this embodiment, the random number generator 7 generates a random number for the surviving normal laser diodes except for the failed laser diode, and sequentially emits the surviving normal laser diodes based on the random numbers. By controlling the order to be random, even when the number of laser diodes is reduced, optimization of heat distribution can be maintained, and stable operation can be continued.
[0058]
【The invention's effect】
According to the first aspect of the present invention, a plurality of light emitting elements are selectively and sequentially switched for the same transmission data to emit light. Concentration of heat to a local area as in the case of an element can be avoided, and heat dissipation can be facilitated by increasing the thermal conductance between the cooling mechanism by increasing the heating area. The operation can be stabilized with a decrease in the operating temperature of such a light emitting element.
[0059]
According to the second aspect of the present invention, in the optical transmitter according to the first aspect, a configuration suitable for optical communication can be obtained by using a laser diode as the light emitting element.
[0060]
According to the third aspect of the present invention, in the optical transmitter according to the second aspect, since a surface emitting semiconductor laser (VCSEL) is used as the laser diode, the arrangement and wiring of the light emitting elements are facilitated. And the array can be easily formed.
[0061]
According to the fourth aspect of the invention, in the optical transmitter according to any one of the first to third aspects, the plurality of light emitting elements are sequentially switched at a constant time period, so that the amount of heat generated per unit area is reduced. Therefore, the system can be stabilized, and higher speed and higher reliability can be obtained.
[0062]
According to the fifth aspect of the present invention, in the optical transmitter according to any one of the first to third aspects, the light emission of each light emitting element is sequentially controlled in synchronization with the modulation of the data sequence as transmission data. In addition, control can be performed so as to change the switching timing according to the amount of data, etc., so that control according to the use situation can be performed, heat generation can be made uniform, and the system can be further stabilized. And further higher speed and higher reliability can be obtained.
[0063]
According to the sixth aspect of the present invention, in the optical transmitter according to any one of the first to third aspects, the light emitting element that sequentially emits light for each packet which is the most basic unit of the transmission data is controlled. Therefore, it is easy to obtain a time margin between packets, it is possible to set an appropriate switching time, and it is possible to ease the demand for the high-speed operation of the light emission control means sequentially, and it is possible to obtain a configuration advantageous in cost. .
[0064]
According to the seventh aspect of the present invention, in the optical transmitter according to any one of the first to sixth aspects, when the light emitting elements arranged and arranged simply emit light sequentially, the light is emitted at itself and before and after timing. When the switching speed of the light-emitting element control means is slow, the temperature of the light-emitting portion may be excessively increased. In this example, the order in which light is emitted one by one so as to be discontinuous is set so as to be discrete, such as every other two, so that local heat concentration can be reduced and the heat generation distribution for a plurality of light emitting elements can be equalized. Therefore, the requirement of the high-speed operation for the sequential light emission control means can be relaxed, and a configuration advantageous in cost can be obtained.
[0065]
According to the eighth aspect of the present invention, in the optical transmitter according to any one of the first to sixth aspects, if the control of the light emission order is skipped, the number of light emitting elements may be fractional or the light emission may be regular. Depending on the order, it may be difficult to equalize the heat generation distributions for a plurality of light emitting elements.However, since the light emission order is controlled randomly based on random numbers, the heat generation distributions for a plurality of light emitting elements are equalized over a long term. Can be
[0066]
According to the ninth aspect of the present invention, in the optical transmitter according to any one of the first to eighth aspects, when a failure occurs in a plurality of light emitting elements, light emission is scheduled to occur next to the failed light emitting element. Since the light emission order is changed so as to cause the light emitting element to emit light, stable optical communication that is not affected by a failure can be performed.
[0067]
According to the tenth aspect, in the optical transmitter according to any one of the first to seventh aspects, when a failure occurs in a plurality of light emitting elements, the light emitting elements are basically skipped. It is sufficient to emit light, but for example, there is a concern that optimal heat distribution may not be achieved when an existing pattern of a specific failed light emitting element occurs due to, for example, a failure of an adjacent light emitting element. Since the light emission control is re-defined sequentially using the surviving light emitting elements except for the failed light emitting element, the heat dispersion can be optimized, and the stable operation can be continued.
[0068]
According to the eleventh aspect of the present invention, in the optical transmitter according to the eighth aspect, when a failure occurs in a plurality of light emitting elements, basically, the light emitting elements may be skipped to emit light. For example, there is a concern that optimal heat distribution may not be achieved when a specific failure light emitting element is present, for example, because adjacent light emitting elements have failed successively. A random number is generated for the surviving light-emitting elements, and the order in which each light-emitting element emits light sequentially based on the random number is randomized, so that even when the number of light-emitting elements decreases, optimization of heat distribution can be maintained. , A stable operation can be continued.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram illustrating a configuration example of an optical transmitter according to a first embodiment of the present invention.
FIG. 2 is a schematic block diagram illustrating a configuration example of an optical transmitter according to a second embodiment of the present invention.
FIG. 3 is a schematic block diagram illustrating a configuration example of an optical transmitter according to a third embodiment of the present invention.
FIG. 4 is an explanatory diagram illustrating order control according to a fourth embodiment of the present invention.
FIG. 5 is a schematic block diagram illustrating a configuration example of an optical transmitter according to a fifth embodiment of the present invention.
FIG. 6 is a schematic block diagram illustrating a configuration example of an optical transmitter according to a sixth embodiment of the present invention.
FIG. 7 is a schematic block diagram illustrating a configuration example of an optical transmitter according to an eighth embodiment of the present invention.
[Explanation of symbols]
3 Waveguide
4 Sequential light emission control means
8 Failure detection means
LD1 to LDn light emitting element, laser diode

Claims (11)

A plurality of light emitting elements that are provided in common for the same transmission data and whose output side is connected to a single waveguide,
Sequential light emission control means for selectively controlling the light emission of each light emitting element among these light emitting elements and outputting the transmission data as an optical signal into the waveguide;
An optical transmitter comprising: The optical transmitter according to claim 1, wherein the light emitting element is a laser diode. The optical transmitter according to claim 2, wherein the laser diode is a surface emitting semiconductor laser (VCSEL). 4. The optical transmitter according to claim 1, wherein the sequential light emission control unit sequentially controls the light emission of each light emitting element in a fixed time cycle in accordance with an input of the data string as the transmission data. 5. 4. The optical transmitter according to claim 1, wherein the sequential light emission control unit sequentially controls light emission of each light emitting element in synchronization with a modulation of a data string as the transmission data. 5. 4. The optical transmitter according to claim 1, wherein the sequential light emission control unit sequentially controls light emission of each light emitting element for each packet with respect to the packet data as the transmission data. 5. Aligning the light emitting elements,
The optical transmitter according to any one of claims 1 to 6, wherein the sequential light emission control unit sets the order in which each light emitting element emits light sequentially and discontinues between adjacent light emitting elements. The optical transmitter according to any one of claims 1 to 6, wherein the sequential light emission control unit sets the order in which each light emitting element emits light sequentially based on a random number. Comprising a failure detection means for detecting a failed light emitting element in the light emitting element,
9. The light emitting device according to claim 1, wherein the sequential light emission control unit changes a light emission order to a light emitting element scheduled to emit light next to the light emitting element when the failed light emitting element is detected by the failure detection means. 10. Optical transmitter. Comprising a failure detection means for detecting a failed light emitting element in the light emitting element,
8. The sequential light emission control unit according to claim 1, wherein when a failed light emitting element is detected by the failure detection unit, the sequential light emission control unit redefines the sequential light emission control for the remaining light emitting elements excluding the light emitting element. 9. Optical transmitter. Comprising a failure detection means for detecting a failed light emitting element in the light emitting element,
The sequential light emission control means, when a failed light emitting element is detected by the failure detection means, generates a random number for the remaining light emitting elements excluding the light emitting element and sequentially emits the light emitting elements based on the random number. 9. The optical transmitter according to claim 8, wherein is random.

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