Transceiver, terminal device and transceiver system

Abstract

A transceiver device, a terminal device, and a transceiver system are provided. The transceiver device (11) includes a control unit (51), a drive unit (52), a specific pattern generation unit (53), a transmit signal detection unit (54), an amplification unit (55), a differential amplifier (56), an average current detection unit (57), and a receive signal detection unit (58). During periods without signal, the control unit (51) causes a current signal to be input from the drive unit (52) to the laser diode (12) and outputs an optical signal from the laser diode (12). The length of this period depends on the average value of the current signal output from the photodiode (23) of the receiving party (the detection result of the average current detection unit (67)) over the entire period. When a specific pattern optical signal output from the laser diode (22) of the receiving party reaches the photodiode (13), the magnitude of the current signal input from the drive unit (52) to the laser diode (12) is adjusted based on the length of the period of the specific pattern optical signal.

Description

Technical Field

[0001] This invention relates to transceivers, terminal devices, and transceiver systems. Background Technology

[0002] In a transceiver system that communicates via optical signals, the optical signal output from the laser diode, based on an electrical signal, is received by the photodiode of the receiving terminal and converted into an electrical signal. The intensity modulation pattern of the optical signal corresponds to the intensity modulation pattern of the electrical signal to be transmitted. By transmitting optical signals in the opposite direction, bidirectional communication is possible. Using optical fiber as the transmission path for transmitting optical signals from the laser diode to the photodiode enables long-distance optical transmission with low loss.

[0003] The driving section of the laser diode generates a current signal based on the electrical signal (voltage signal) to be transmitted, and supplies this current signal to the laser diode. The laser diode then outputs a light signal corresponding to this current signal. The photodiode receiving the light signal outputs a current signal corresponding to the amount of light received. The current output from the photodiode is very small. The amplification section converts this small current signal from the photodiode into a voltage signal of sufficient amplitude and outputs this voltage signal. This amplification section that converts the current signal into a voltage signal is called a transimpedance amplifier (TIA).

[0004] The driver and amplification sections can be fabricated as inexpensive, high-speed circuits on silicon chips. Laser diodes, however, cannot be made of silicon and are fabricated on compound semiconductor chips. Photodiodes can be made of silicon, but due to differences in optimal processes compared to the driver and amplification sections, they are fabricated on different chips. Therefore, while the driver and amplification sections can be fabricated on a common silicon chip, laser diodes and photodiodes are on separate chips.

[0005] Figure 1 and Figure 2 This is a graph showing the relationship between the output optical power P of the laser diode's optical signal LS and the supply current I of the current signal CS. The supply current I varies with time t. The output optical power P also varies with time t. As these graphs show, when the supply current I is less than the threshold current I... TH Within a certain range, the laser diode emits almost no light. Conversely, when the supply current I is greater than the threshold current I0, the laser diode emits almost no light. TH Within a certain range, the output optical power P of the laser diode corresponds to the supply current value I. Figure 1 This shows that the current signal CS input to the laser diode is always greater than the threshold current I. TH The situation. Figure 2This shows that the L level of the current signal CS input to the laser diode is less than the threshold current I. TH The situation.

[0006] Let T be the time when the supply current I to the laser diode changes from level L to level H. I Let T be the time when the output optical power P of the laser diode changes from L level to H level in response to this transition. P .like Figure 2 As shown, the L level of the current signal CS input to the laser diode is less than the threshold current I. TH In this case, from time T I At time T P The period (T) P -T I The jitter is caused by the random variation of the turn-on delay defined in the code. Additionally, as... Figure 2 As shown, the L level of the current signal CS input to the laser diode is higher than the threshold current I. TH In small cases, the output optical power P of the laser diode's optical signal LS after the current signal CS transitions from L level to H level experiences ringing (a time variation) due to the need to mitigate vibrations; this is also known as jitter. To suppress random variations in the turn-on delay and ringing, and to suppress jitter, as follows... Figure 1 As shown, the L level of the current signal CS input to the laser diode is required to be greater than the threshold current I. TH .

[0007] If we assume that the H-level value of the output optical power P of the laser diode is P... H Let the output optical power P of the laser diode at level L be P L (=αP H ), then the ratio of the two (P) H / P L The extinction ratio is defined as 1 / α. If the level of the optical signal LS is to be reliably identified by the photodiode, then a larger extinction ratio is preferred.

[0008] To effectively suppress jitter in the output optical power P, it is desirable that the L level of the current signal CS input to the laser diode is sufficiently large compared to the threshold current. On the other hand, to increase the extinction ratio of the output optical power P, it is preferable that the L level of the current signal CS input to the laser diode is relatively small within a range above the threshold current. That is, jitter suppression and ensuring the extinction ratio are at a trade-off. Therefore, considering both jitter suppression and ensuring the extinction ratio, it is desirable to set the L and H levels of the current signal CS input to the laser diode to appropriate values.

[0009] However, the threshold current of a laser diode varies significantly with temperature and over time. For example, the threshold current increases by 1-2% when the temperature rises by 1°C. Therefore, even if the L and H levels of the current signal CS input to the laser diode are set to appropriate values, jitter suppression becomes insufficient or the extinction ratio deteriorates when the threshold current changes due to temperature variations or over time, while maintaining these settings. Furthermore, if the L and H levels of the current signal CS input to the laser diode are set to values ​​greater than appropriate as the threshold current increases, power consumption increases.

[0010] The device disclosed in Patent Document 1 adjusts the magnitude of the current signal supplied from the driving unit to the laser diode based on temperature in the terminal device on the transmitting side. That is, in this device, when the temperature increases, the threshold current increases, thus increasing the current signal; when the temperature decreases, the threshold current decreases, thus decreasing the current signal.

[0011] The device disclosed in Patent Document 2 includes a monitoring photodiode positioned near the laser diode in the terminal device on the transmitting side. The monitoring photodiode detects the power of the light output from the laser diode. Then, in this device, the magnitude of the current signal supplied from the driving unit to the laser diode is adjusted to keep the average value of the detected output light power constant.

[0012] The apparatus disclosed in Patent Document 3 detects the average output current of the photodiode that receives the optical signal in the receiving terminal device, and sends an electrical signal corresponding to the detected value from the receiving terminal device to the transmitting terminal device. Furthermore, in this apparatus, the transmitting terminal device adjusts the magnitude of the current signal supplied from the driving unit to the laser diode based on the electrical signal sent from the receiving terminal device.

[0013] The aforementioned patent documents 1 to 3 are as follows.

[0014] Patent Document 1: US Patent No. 5043992

[0015] Patent Document 2: US Patent No. 8,989,227

[0016] Patent Document 3: US Patent No. 8,521,019 Summary of the Invention

[0017] The device disclosed in Patent Document 1, when adjusting the magnitude of the current signal supplied from the driving unit to the laser diode, does not perform feedback control based on the output optical power of the laser diode, but rather performs temperature-based feedforward control. Therefore, it is difficult to adjust the magnitude of the current signal with high precision. In addition, this device cannot cope with the problem of threshold current variation caused by the deterioration of the laser diode over the years.

[0018] The device disclosed in Patent Document 2 performs feedback control based on the output optical power of the laser diode when adjusting the magnitude of the current signal supplied from the driving unit to the laser diode. Therefore, it can adjust the magnitude of the current signal with high precision. In addition, it can also cope with the problem of threshold current variation caused by the deterioration of the laser diode over the years. However, this device requires the use of an expensive laser diode with a monitoring photodiode placed nearby, thus increasing the cost of the system.

[0019] In order to send an electrical signal corresponding to the detected value of the average output current of the photodiode that received the optical signal to the transmitting terminal device from the receiving terminal device, the device disclosed in Patent Document 3 requires copper wires, which increases the cost of the system.

[0020] A transceiver system is sought that enables bidirectional communication via the transmission of optical signals output from a laser diode, and that can precisely adjust the magnitude of the current signal supplied to the laser diode with an inexpensive structure. Furthermore, a terminal device used in such a transceiver system, and the transceiver devices included in that terminal device, are also sought.

[0021] The transceiver device disclosed herein (first transceiver device) is a transceiver device that performs bidirectional signal transmission and reception with a counterpart transceiver device (second transceiver device). The transceiver device includes: (1) a drive unit that, based on a signal to be transmitted to the counterpart transceiver device, inputs a current signal to a laser diode, causing the laser diode to output an optical signal to a counterpart photodiode on the counterpart transceiver device side. The transceiver device also includes: (2) an amplification unit that inputs the current signal output from the photodiode, converts the current signal into a voltage signal, and outputs the voltage signal, wherein the photodiode receives the optical signal arriving from the counterpart laser diode on the counterpart transceiver device side. The transceiver device further includes: (3) an average current detection unit that detects the average value of the current signal output from the photodiode. Finally, the transceiver device includes: (4) a control unit that controls the input of the current signal from the drive unit to the laser diode.

[0022] It should also be noted that the second transceiver can have the same structure as the first transceiver.

[0023] During a signal-free period when there is no signal to be transmitted or received between the control unit and the other transceiver, (a) the control unit inputs a current signal from the drive unit to the laser diode, causing the laser diode to output an optical signal. When a specific pattern of optical signal output from the other laser diode arrives at the photodiode during the entire period, the control unit adjusts the magnitude of the current signal input from the drive unit to the laser diode based on the duration of the specific pattern of optical signal. (b) The control unit can also input a specific pattern of current signal from the drive unit to the laser diode and output a specific pattern of optical signal from the laser diode during the entire period, the duration of which depends on the average value of the current signal detected by the average current detection unit.

[0024] The power of the optical signal in a specific mode is preferably increased or decreased repeatedly around the power before and after the period of that specific mode. Alternatively, it is also preferable to have a power that is different from the power before and after the period of that specific mode.

[0025] The terminal device disclosed herein includes: the transceiver device (first transceiver device) described above; the laser diode that receives a current signal from the drive section of the transceiver device and outputs an optical signal; and the photodiode that receives the optical signal and outputs a current signal to the amplification section of the transceiver device.

[0026] The transceiver system disclosed herein includes a first terminal device and a second terminal device as the aforementioned terminal devices. The photodiode of the second terminal device receives an optical signal output from a laser diode of the first terminal device, and the photodiode of the first terminal device receives an optical signal output from a laser diode of the second terminal device. Preferably, the transceiver system further includes: a first optical fiber that guides the optical signal output from the laser diode of the first terminal device to the photodiode of the second terminal device; and a second optical fiber that guides the optical signal output from the laser diode of the second terminal device to the photodiode of the first terminal device.

[0027] According to the transceiver device, bidirectional communication can be carried out through the transmission of optical signals output from the laser diode, and the magnitude of the current signal supplied to the laser diode can be adjusted with high precision in a cost-effective structure. Attached Figure Description

[0028] Figure 1 This is a graph showing the relationship between the output optical power P and the supply current I in a laser diode.

[0029] Figure 2 This is a graph showing the relationship between the output optical power P and the supply current I in a laser diode.

[0030] Figure 3 This is a diagram showing the structure of transceiver system 1.

[0031] Figure 4 This is a diagram showing the structure of transceiver device 11 and transceiver device 21.

[0032] Figure 5 This is a circuit example of the average current detection unit 57 of the transceiver device 11.

[0033] Figure 6 This is a graph showing the relationship between the output optical power P and the supply current I in a laser diode.

[0034] Figure 7A , Figure 7B , Figure 7C , Figure 7D This is a timing diagram illustrating an example of the operation of transceiver system 1 when individual adjustments are made using the first mode as a specific mode during periods of no signal.

[0035] Figure 8A , Figure 8B , Figure 8C , Figure 8D This is a timing diagram illustrating an example of the operation of transceiver system 1 when the second mode is used as a specific mode for individual adjustments during periods of no signal.

[0036] Figure 9A , Figure 9B , Figure 9C , Figure 9D This is a timing diagram illustrating an example of the operation of transceiver system 1 when simultaneously adjusting using the first mode as a specific mode during periods of no signal.

[0037] Figure 10A , Figure 10B , Figure 10C , Figure 10D This is a timing diagram illustrating an example of the operation of transceiver system 1 when simultaneously adjusting using the second mode as a specific mode during periods of no signal. Detailed Implementation

[0038] Hereinafter, with reference to the accompanying drawings, a detailed description of the methods for carrying out the invention will be provided. It should be noted that in the description of the drawings, the same elements are labeled with the same reference numerals, and repeated descriptions are omitted. The invention is not limited to these illustrations, but is shown by the claims, and is intended to include all modifications with the same meaning and scope as the claims.

[0039] Figure 3This is a diagram showing the structure of transceiver system 1. Transceiver system 1 includes terminal device 10 and terminal device 20. Terminal device 10 includes transceiver device 11, laser diode 12, and photodiode 13. Terminal device 20 includes transceiver device 21, laser diode 22, and photodiode 23. Terminal device 10 and terminal device 20 can have the same structure as each other.

[0040] The optical signal output from the laser diode 12 of the terminal device 10 is received by the photodiode 23 of the terminal device 20. The optical signal output from the laser diode 22 of the terminal device 20 is received by the photodiode 13 of the terminal device 10. The optical signal output from the laser diode 12 can propagate through space and reach the photodiode 23, but preferably it is guided by the optical fiber 30 to reach the photodiode 23. Similarly, the optical signal output from the laser diode 22 can also propagate through space and reach the photodiode 13, but preferably it is guided by the optical fiber 40 to reach the photodiode 13. By using optical fiber to guide the optical signal, long-distance optical transmission with low loss is possible.

[0041] Additionally, terminal device 10 includes connector 14, and terminal device 20 includes connector 24. The transceiver 11 of terminal device 10 supplies a current signal to laser diode 12 based on a voltage signal input to connector 14, outputs an optical signal from laser diode 12, converts the current signal output from photodiode 13 (which receives the optical signal) into a voltage signal, and outputs the voltage signal from connector 14. Similarly, the transceiver 21 of terminal device 20 supplies a current signal to laser diode 22 based on a voltage signal input to connector 24, outputs an optical signal from laser diode 22, converts the current signal output from photodiode 23 (which receives the optical signal) into a voltage signal, and outputs the voltage signal from connector 24.

[0042] Active optical cables (AOCs) have the following structure: In an AOC, a transceiver, a laser diode, and a photodiode are mounted on a substrate called a paddle card. Furthermore, the transceiver is electrically connected to a connector, the laser diode is optically connected to the light-input end of one optical fiber, and the photodiode is optically connected to the light-output end of the other optical fiber.

[0043] Figure 4 This is a diagram showing the structure of transceiver 11 and transceiver 21. The diagram also shows a laser diode 12 and a photodiode 13 located on the transceiver 11 side, and a laser diode 22 and a photodiode 23 located on the transceiver 21 side.

[0044] Transceiver 11 includes a control unit 51, a drive unit 52, a specific pattern generation unit 53, a transmit signal detection unit 54, an amplification unit 55, a differential amplifier 56 (differential amplification unit), an average current detection unit 57, and a receive signal detection unit 58. Transceiver 21 includes a control unit 61, a drive unit 62, a specific pattern generation unit 63, a transmit signal detection unit 64, an amplification unit 65, a differential amplifier 66 (differential amplification unit), an average current detection unit 67, and a receive signal detection unit 68. Transceiver 11 and transceiver 21 have the same structure, and structural elements with the same name in transceiver 11 and transceiver 21 have the same function.

[0045] The following mainly describes the structure of transceiver 11, one of the transceiver devices 11 and 21. Transceiver 11 performs bidirectional signal transmission and reception with the other transceiver 21. Control unit 51 receives the detection results from the transmit signal detection unit 54, the average current detection unit 57, and the receive signal detection unit 58, and controls the operation of drive unit 52 and differential amplifier 56 respectively.

[0046] When a signal is present that should be transmitted to the other party's transceiver 21, the drive unit 52 inputs a current signal to the laser diode 12 based on the signal, and outputs an optical signal from the laser diode 12 to the other party's photodiode 23. The signal (voltage signal) input to the drive unit 52 can also be a differential signal. Furthermore, during periods of no signal transmission or reception between the drive unit 52 and the other party's transceiver 21, the drive unit 52 inputs a current signal of a specific pattern generated by the specific pattern generation unit 53 to the laser diode 12, and outputs an optical signal of the specific pattern from the laser diode 12 to the other party's photodiode 23.

[0047] The specific pattern generation unit 53 generates a specific pattern of the current signal supplied by the drive unit 52 to the laser diode 12 during periods without a signal. The transmission signal detection unit 54 detects whether there is a signal that should be transmitted to the other party's transceiver device 21 and notifies the control unit 51 of the detection result. The transmission signal detection unit 54 can detect the presence or absence of a signal that should be transmitted based on the magnitude of the temporal variation in the level of the signal (voltage signal) input to the drive unit 52.

[0048] The amplification unit 55 receives a current signal from the photodiode 13 that receives the optical signal from the laser diode 22 of the other party, converts the current signal into a voltage signal, and outputs the voltage signal. This amplification unit 55 is a TIA that converts a current signal into a voltage signal. The voltage signal output from the amplification unit 55 can be a differential signal. The differential amplifier 56 amplifies the signal output from the amplification unit 55 and outputs it. During periods of no signal transmission (when no signal is received from the transceiver device 21), the differential amplifier 56 can be controlled by the control unit 51 to make its output terminal a high-impedance state.

[0049] The average current detection unit 57 detects the average value of the current signal output from the photodiode 13 and notifies the control unit 51 of the detection result. When the value of the current signal output from the photodiode 13 changes over time, the average current detection unit 57 calculates a moving average (low-frequency component) by smoothing the time-varying current signal. The received signal detection unit 58 monitors the voltage signal output from the amplification unit 55, detects the level of the voltage signal, and notifies the control unit 51 of the detection result.

[0050] The control unit 51 receives the detection results from the transmit signal detection unit 54, the average current detection unit 57, and the receive signal detection unit 58. Based on these detection results, the control unit 51 determines whether there is a signal that should be transmitted from the transceiver 11 side to the other transceiver 21 side, and also determines whether there is a signal transmitted from the other transceiver 21 side to the transceiver 11 side. Thus, the control unit 51 can detect periods of no signal transmission or reception with the other transceiver 21 side. During these detected periods of no signal transmission or reception, the control unit 51 sets the output of the differential amplifier 56 to a high-impedance state.

[0051] During periods without a signal, the control unit 51 inputs a current signal from the drive unit 52 to the laser diode 12, and outputs a light signal from the laser diode 12. When a light signal of a specific pattern output from the laser diode 22 of the other party reaches the photodiode 13 within a period in which the length of the period depends on the average value of the current signal output from the photodiode 23 of the other party that received the light signal (the detection result of the average current detection unit 67), the magnitude of the current signal input from the drive unit 52 to the laser diode 12 is adjusted based on the length of the period of the light signal of that specific pattern.

[0052] During periods without a signal, the control unit 51 inputs a current signal of a specific pattern from the drive unit 52 to the laser diode 12 and outputs a light signal of a specific pattern from the laser diode 12 throughout the entire interval of a period that depends on the length of the average value of the current signal detected by the average current detection unit 57.

[0053] The duration of a specific mode can be set to any of several levels, but it is preferable to set it to any of two levels based on the comparison between the average value of the current signal detected by the average current detection units 57 and 67 and the threshold (target value).

[0054] Figure 5 This is a circuit example of the average current detection unit 57 of the transceiver device 11. The figure also shows a photodiode 13 and an amplifier 55. The average current detection unit 57 includes a differential amplifier 71, a PMOS transistor 72, a capacitor 73, a PMOS transistor 74, a resistor 75, and a comparator 76.

[0055] The anode of photodiode 13 is connected to the input terminal of amplification section 55. The cathode of photodiode 13 is connected to the non-inverting input terminal of differential amplifier 71. A constant reference voltage Vref is input to the inverting input terminal of differential amplifier 71. The output terminal of differential amplifier 71 is connected to the gates of PMOS transistors 72 and 74. The sources of PMOS transistors 72 and 74 are connected to the power supply potential. The drain of PMOS transistor 72 is connected to the non-inverting input terminal of differential amplifier 71, and also to the ground potential supply terminal via capacitor 73. The drain of PMOS transistor 74 is connected to one input terminal of comparator 76, and also to the ground potential supply terminal via resistor 75. A constant threshold voltage Vth is input to the other input terminal of comparator 76. Comparator 76 compares the voltage values ​​input to the two input terminals respectively, and outputs a signal representing the comparison result from the output terminal.

[0056] PMOS transistor 72 functions as a current source. Differential amplifier 71, PMOS transistor 72, and capacitor 73 constitute an LDO (Low Dropout) regulator. The voltage Vbias at the non-inverting input terminal of differential amplifier 71 is equal to the constant reference voltage Vref input to the inverting input terminal of differential amplifier 71. This constant voltage Vbias is supplied to the cathode of photodiode 13. The AC component (high-frequency component) of the current signal output from photodiode 13 flows to capacitor 73, while the average current (low-frequency component) flows between the source and drain of PMOS transistor 72.

[0057] PMOS transistors 72 and 74 form a current mirror circuit. One terminal of transistor 72 is connected to the power supply potential VDD, and the other terminal is connected to ground potential via capacitor 73. One terminal of transistor 74 is connected to the power supply potential VDD, and the other terminal is connected to ground potential via resistor 75. The current flowing between the source and drain of PMOS transistor 74 (i.e., the current flowing through resistor 75) is equal to the current flowing between the source and drain of PMOS transistor 72. The voltage value input to one input terminal of comparator 76 is the product of the current flowing through resistor 75 and the resistance value of resistor 75, Vave. Comparator 76 compares the voltage value Vave with the threshold voltage Vth and outputs a signal indicating which of the two voltage values ​​is larger. The signal output from the output terminal of comparator 76 indicates whether the average value (low-frequency component) of the current signal output from photodiode 13 is greater than the target value.

[0058] In this embodiment, the transceiver 11 can adjust the magnitude of the current signal supplied to the laser diode 12 under the control of the control unit 51 during periods without signal. Similarly, the transceiver 21 can adjust the magnitude of the current signal supplied to the laser diode 22 under the control of the control unit 61 during periods without signal.

[0059] Figure 6 This is a graph showing the relationship between the output optical power P and the supply current I in a laser diode. The graph illustrates the adjustment of the magnitude of the current signal supplied from the driver to the laser diode. The supply current I varies with time t. The output optical power P also varies with time t. The current signal CSa before the characteristic change is represented by a solid line, and the current signal CSb after the characteristic change is represented by a dashed line. The current / output optical power characteristic CHa of the optical signal LS before the characteristic change is represented by a solid line, and the current / output optical power characteristic CHb of the optical signal LS after the characteristic change is represented by a dashed line. Due to temperature changes or deterioration over time, the characteristic between the output optical power P and the supply current I in the laser diode changes from the characteristic CHa shown by the solid line to the characteristic CHb shown by the dashed line. When such a characteristic change occurs, in order to suppress the change in the magnitude of the optical signal LS output from the laser diode, the magnitude of the current signal supplied from the driver to the laser diode is changed from the current signal CSa represented by the solid line to the current signal CSb represented by the dashed line.

[0060] In this embodiment, since it is based on feedback control, the magnitude of the current signal supplied to the laser diode can be adjusted with high precision. Furthermore, in this embodiment, as with the device disclosed in Patent Document 2, there is no need to use an expensive laser diode with a monitoring photodiode located nearby; and as with the device disclosed in Patent Document 3, there is no need to provide additional copper wires outside the optical fiber, thus enabling a low-cost structure.

[0061] Next, an example of the operation of transceiver system 1 will be described. When a signal that should be transmitted from transceiver device 11 to transceiver device 21 is present, the drive unit 52 provides a current signal corresponding to the signal (voltage signal) to the laser diode 12, and the laser diode 12 outputs an optical signal corresponding to the current signal. When the optical signal output from the laser diode 12 reaches the photodiode 23 of the other party, the photodiode 23 outputs a current signal corresponding to the optical signal, the amplification unit 65 converts the current signal into a voltage signal, and the differential amplifier 66 (differential amplifier unit) amplifies the voltage signal before outputting it. The same applies when a signal that should be transmitted from transceiver device 21 to transceiver device 11 is present.

[0062] The system can detect periods of no signal transmission when there is no signal to be transmitted from either transceiver 11 or transceiver 21 in the following manner: When there is no signal to be transmitted from transceiver 11 to transceiver 21, the transmission signal detection unit 54 detects this and notifies the control unit 51 of the detection result. Furthermore, under the control of the control unit 51, current is not supplied to the laser diode 12 from the drive unit 52, and light is not output from the laser diode 12. In transceiver 21, the average current detection unit 67 detects that no light reaches the photodiode 23 from the laser diode 12 and notifies the control unit 61 of the detection result. Similarly, when there is no signal to be transmitted from transceiver 21 to transceiver 11, the transmission signal detection unit 64 detects this and notifies the control unit 61 of the detection result. Furthermore, under the control of the control unit 61, current is not supplied to the laser diode 22 from the drive unit 62, and light is not output from the laser diode 22. In the transceiver 11, the average current detection unit 57 detects that no light reaches the photodiode 13 from the laser diode 22 and notifies the control unit 51 of the detection result. In this way, the control unit 51 of the transceiver 11 and the control unit 61 of the transceiver 21 can detect no-signal periods when there are no signals to be transmitted or received between the transceiver 11 and the transceiver 21.

[0063] The no-signal period exists not only between the normal communication period (the period during which the original signal should be transmitted) and the next normal communication period, but also during startup. In either case, the magnitude of the current signal input from the drive unit 52 to the laser diode 12 can be adjusted. If adjustment is made during the no-signal period at startup, the magnitude of the current signal input to the laser diode 12 can be optimized even if the characteristics of the laser diode 12 change due to years of degradation at that time. If adjustment is made during the no-signal period between normal communication periods, the magnitude of the current signal input to the laser diode 12 can be maintained at an optimal level even if the characteristics of the laser diode 12 change due to temperature variations during operation.

[0064] During periods without signal, the magnitude of the current signal supplied from the drive unit 52 to the laser diode 12 on the transceiver 11 side and the magnitude of the current signal supplied from the drive unit 62 to the laser diode 22 on the transceiver 21 side can be adjusted individually, or they can be adjusted substantially simultaneously.

[0065] A specific mode can take many forms. A specific mode simply needs to be able to distinguish its period from other periods during a period without a signal. The optical signal of a specific mode can also be a mode in which the power repeatedly increases or decreases around the power before and after the specific mode's period (hereinafter referred to as "first mode"). Alternatively, the optical signal of a specific mode can also be a mode with a power different from the power before and after the specific mode's period (hereinafter referred to as "second mode").

[0066] Next, using Figures 7 to 10, an example of the operation of the transceiver system 1 during a signal-free period will be described. This operation is performed under the control of control units 51 and 61. In the case of individual adjustments, the magnitude of the current signal supplied from the drive unit 52 on the transceiver device 11 side to the laser diode 12, and the magnitude of the current signal supplied from the drive unit 62 on the transceiver device 21 side to the laser diode 22, can be adjusted in the same way. Therefore, in the following description of the operation example of individual adjustments, the adjustment of the magnitude of the current signal supplied from the drive unit 52 on the transceiver device 11 side to the laser diode 12 will be mainly explained.

[0067] Figure 7A , Figure 7B , Figure 7C , Figure 7D This is a timing diagram illustrating an example of the operation of transceiver system 1 when individual adjustments are made using the first mode as a specific mode during periods of no signal. Figure 7A This is a timing diagram showing the optical signal output from the laser diode 12 on the transceiver 11 side. Figure 7B This is a timing diagram showing the average current signal output from photodiode 23 on the transceiver 21 side. Figure 7CThis is a timing diagram showing the optical signal output from the laser diode 22 on the transceiver 21 side. Figure 7D The timing diagrams show the voltage signals output from the amplifier 55 on the transceiver 11 side. The waveforms of each signal are schematically shown in these timing diagrams.

[0068] In the first cycle P1, on the transceiver 11 side, corresponding to the current signal input from the drive unit 52 to the laser diode 12, an optical signal with a constant amplitude and repeatedly increasing and decreasing power is output from the laser diode 12. Figure 7A The target value of the center (average value) of the amplitude of the optical signal output from laser diode 12 is the target value TGa.

[0069] The photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12, and the average current detection unit 67 calculates the average value (=Iave) of the current signal output from the photodiode 23. (23) ()( Figure 7B The current signal output from photodiode 23 is compared with the target value TGb. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 23 is... (23) ()( Figure 7B ) is greater than the target value TGb (TGb < Iave) (23) During the entire period T1, which depends on this result, a current signal of a specific mode is input from the drive unit 62 to the laser diode 22, and a light signal of a specific mode is output from the laser diode 22. Figure 7C During period T1, there is information indicating that the laser output is too high. The power of the optical signal in periods other than T1 is equal to the average power of the optical signal in period T1.

[0070] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22, and the amplification unit 55 converts the current signal output from the photodiode 13 into a voltage signal. Figure 7D When the voltage signal output from the amplification unit 55 is a differential signal, the presence or absence of the amplitude of the differential signal is detected by the receiving signal detection unit 58, thereby detecting the length of the period T1 of the specific mode. Based on the voltage signal output from the amplification unit 55 ( Figure 7D The length of period T1 of a specific mode is determined, and the magnitude of the current signal input from the drive unit 52 to the laser diode 12 is changed in the next second cycle P2. In the example shown in the figure, since the average value of the current signal output from the photodiode 23 is determined in the first cycle P1 (Iave) (23) ()( Figure 7B ) is greater than the target value TGb (TGb < Iave) (23)Therefore, in the next second cycle P2, the magnitude of the current signal input from the drive unit 52 to the laser diode 12 is smaller than the current signal in the first cycle P1. If during period T1 an indication that the laser output is too high, the gain or bias potential of the drive unit 52 is reduced. The control unit 51 can be connected to the gain adjustment terminal or bias adjustment terminal of the drive unit 52.

[0071] In the second cycle P2, on the transceiver 11 side, based on the modified (smaller than the previous first cycle P1) current signal input from the drive unit 52 to the laser diode 12, an optical signal with a constant amplitude and repeatedly increasing and decreasing power is output from the laser diode 12. Figure 7A ).

[0072] The photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12, and the average current detection unit 67 calculates the average value of the current signal output from the photodiode 23 (Iave). (23) ()( Figure 7B The current signal output from photodiode 23 is compared with the target value TGb. In the illustrated example, the average value (Iave) of the current signal output from photodiode 23 is... (23) ()( Figure 7B ) is less than the target value TGb(Iave) (23) <TGb), during the entire period T2 depending on this result, a specific mode of current signal is input from the drive unit 62 to the laser diode 22, and a specific mode of light signal is output from the laser diode 22. Figure 7C The power of the optical signal during periods other than T2 is equal to the average power of the optical signal during period T2. If the laser output is too low during period T2, the gain or bias potential of the drive unit 52 is increased. The control unit 51 can be connected to the gain adjustment terminal or bias adjustment terminal of the drive unit 52.

[0073] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22, and the amplification unit 55 converts the current signal output from the photodiode 13 into a voltage signal. Figure 7D When the voltage signal output from the amplification unit 55 is a differential signal, the presence or absence of the amplitude of the differential signal is detected by the received signal detection unit 58, thereby detecting the length of the period T2 of the specific mode. Based on the voltage signal output from the amplification unit 55 ( Figure 7D The length of period T2 of a specific mode is used to change the magnitude of the current signal input from the drive unit 52 to the laser diode 12 in the next third cycle. In the example shown in the figure, in the second cycle P2, the average value (Iave) of the current signal output from the photodiode 23 is determined. (23) ()( Figure 7B) is less than the target value TGb(Iave) (23) <TGb), therefore, the magnitude of the current signal input from the drive unit 52 to the laser diode 12 in the following third cycle is larger than the current signal in the second cycle P2. It should also be noted that the amount of change in this input current can be set to constant in each cycle, or it can be smaller in later cycles.

[0074] Figure 8A , Figure 8B , Figure 8C , Figure 8D This is a timing diagram illustrating an example of the operation of transceiver system 1 when the second mode is used as a specific mode for individual adjustments during periods of no signal. Figure 8A This is a timing diagram showing the optical signal output from the laser diode 12 on the transceiver 11 side. Figure 8B This is a timing diagram showing the average current signal output from photodiode 23 on the transceiver 21 side. Figure 8C This is a timing diagram showing the optical signal output from the laser diode 22 on the transceiver 21 side. Figure 8D The timing diagrams represent the average current signal output from photodiode 13 on the transceiver 11 side. The waveforms of each signal are schematically shown in these timing diagrams.

[0075] In the first cycle P1, on the transceiver 11 side, the laser diode 12 outputs ( Figure 8A The optical signal output from the laser diode 12 corresponds to the current signal input from the drive unit 52, and this optical signal has a constant amplitude, with its power repeatedly increasing and decreasing. The target value of the center (average value) of the amplitude of the optical signal output from the laser diode 12 is the target value TGa.

[0076] The photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12, and the average current detection unit 67 calculates the average value (=Iave) of the current signal output from the photodiode 23. (23) ()( Figure 8B The current signal output from photodiode 23 is compared with the target value TGb. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 23 is... (23) ()( Figure 8B ) is greater than the target value TGb (TGb < Iave) (23) During the entire period T1, which depends on this result, a current signal of a specific mode is input from the drive unit 62 to the laser diode 22, and a light signal of a specific mode is output from the laser diode 22. Figure 8C Set the power of the optical signal in periods other than T1 to a value different from the average power of the optical signal in period T1 (e.g., a smaller value or a cutoff state).

[0077] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22, and the average current detection unit 57 detects the average value of the current signal output from the photodiode 13. Figure 8D The length of the period T1 of a specific pattern is detected. Based on the length of the period T1 of this specific pattern, the magnitude of the current signal input from the drive unit 52 to the laser diode 12 is changed in the next second cycle P2. In the example shown in the figure, since the average value of the current signal output from the photodiode 23 is determined in the first cycle P1 (Iave) (23) ()( Figure 8B ) is greater than the target value TGb (TGb < Iave) (23) Therefore, in the next second cycle P2, the magnitude of the current signal input from the drive unit 52 to the laser diode 12 is smaller than the current signal in the case of the first cycle P1.

[0078] In the second cycle P2, on the transceiver 11 side, an optical signal corresponding to the current signal input from the drive unit 52 to the laser diode 12 is output from the laser diode 12, and this optical signal has a constant amplitude and its power repeatedly increases and decreases. Figure 8A ).

[0079] The photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12, and the average current detection unit 67 calculates the average value of the current signal output from the photodiode 23 (Iave). (23) ()( Figure 8B The current signal output from photodiode 23 is compared with the target value TGb. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 23 is... (23) ()( Figure 8B ) is less than the target value TGb(Iave) (23) <TGb), during the entire period T2 depending on this result, a specific mode of current signal is input from the drive unit 62 to the laser diode 22, and a specific mode of light signal is output from the laser diode 22. Figure 8C Set the power of the optical signal in periods other than T2 to a value different from the average power of the optical signal in period T2 (e.g., a smaller value or a cutoff state).

[0080] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22, and the average current detection unit 57 detects the average value of the current signal output from the photodiode 13. Figure 8DThe length of the period T2 for a specific pattern is detected. Based on the length of the period T2 for that specific pattern, the magnitude of the current signal input from the drive unit 52 to the laser diode 12 is changed in the next third cycle. In the example shown in the figure, since the average value of the current signal output from the photodiode 23 is determined in the second cycle P2 (Iave) (23) ()( Figure 8B ) is less than the target value TGb(Iave) (23) <TGb), therefore, the magnitude of the current signal input from the drive unit 52 to the laser diode 12 in the next third cycle is greater than the current signal in the case of the second cycle P2.

[0081] Figure 9A , Figure 9B , Figure 9C , Figure 9D This is a timing diagram illustrating an example of the operation of transceiver system 1 when simultaneously adjusting using the first mode as a specific mode during periods of no signal. Figure 9A This is a timing diagram showing the optical signal output from the laser diode 12 on the transceiver 11 side. Figure 9B This is a timing diagram showing the average current signal output from photodiode 23 on the transceiver 21 side. Figure 9C This is a timing diagram showing the optical signal output from the laser diode 22 on the transceiver 21 side. Figure 9D The timing diagrams represent the average current signal output from photodiode 13 on the transceiver 11 side. The waveforms of each signal are schematically shown in these timing diagrams.

[0082] In the first cycle P1, the photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12. Figure 9A The target value of the center (average value) of the amplitude of the light signal output from laser diode 12 is the target value TGa. The average value (Iave) of the current signal output from photodiode 23 is measured by the average current detection unit 67. (23) ()( Figure 9B The current signal output from photodiode 23 during a specific mode output period is compared with the target value TGb. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 23 during a specific mode output period is compared with the target value TGb. (23) ()( Figure 9B ) is greater than the target value TGb (TGb < Iave) (23) During the entire period T1, which depends on this result, a current signal of a specific mode is input from the drive unit 62 to the laser diode 22, and a light signal of a specific mode is output from the laser diode 22. Figure 9C The target value of the center (average value) of the amplitude of the optical signal output from laser diode 22 is the target value TGc.

[0083] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22. Figure 9C The average value of the current signal output from the photodiode 13 is obtained by the average current detection unit 57. (13) ()( Figure 9D The current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. (13) ()( Figure 9D ) is less than the target value TGd(Iave) (13) <TGd), during the entire period T1 depending on this result, a current signal of a specific mode is input from the drive unit 52 to the laser diode 12, and a light signal of a specific mode is output from the laser diode 12. Figure 9A ).

[0084] In the first cycle P1, based on the light signal received by photodiode 13 ( Figure 9C Due to the length of period T1 of a specific mode (excessive optical signal output information), the magnitude of the current signal input from the drive unit 52 to the laser diode 12 in the next second cycle P2 is smaller than the current signal in the case of the first cycle P1. Furthermore, in the first cycle P1, based on the optical signal received by the photodiode 23 (…),… Figure 9A The length of the specific mode period T2, the magnitude of the current signal input from the drive unit 62 to the laser diode 22 in the next second cycle P2 is larger than the current signal in the case of the first cycle P1. Figure 9C ).

[0085] In the second cycle P2, the photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12. Figure 9A The average value of the current signal output from the photodiode 23 is obtained by the average current detection unit 67. (23) ()( Figure 9B The current signal output from photodiode 23 during a specific mode output period is compared with the target value TGb. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 23 during a specific mode output period is compared with the target value TGb. (13) ()( Figure 9B ) is less than the target value TGb(Iave) (13) <TGb), during the entire period T2 (light signal output too small information) that depends on this result, a specific mode of current signal is input from the drive unit 62 to the laser diode 22, and a specific mode of light signal is output from the laser diode 22. Figure 9C ).

[0086] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22. Figure 9CThe average value of the current signal output from the photodiode 13 is obtained by the average current detection unit 57. (13) ()( Figure 9D The current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. (13) ()( Figure 9D ) is greater than the target value TGd (TGd < Iave) (13) During the entire period T1, which depends on this result, a current signal of a specific mode is input from the drive unit 52 to the laser diode 12, and a light signal of a specific mode is output from the laser diode 12. Figure 9A ).

[0087] Based on the light signal received by photodiode 13 in the second period P2 ( Figure 9C The length of period T2 in the specific mode of the third cycle is such that the magnitude of the current signal input from the drive unit 52 to the laser diode 12 is greater than the current signal in the case of the second cycle P2. Furthermore, based on the light signal received by the photodiode 23 in the second cycle P2 (the light signal output from the laser diode 12)... Figure 9A The length of the period T1 of the specific mode is such that the magnitude of the current signal input from the drive unit 62 to the laser diode 22 in the next third cycle is smaller than the current signal in the case of the second cycle P2.

[0088] Figure 10A , Figure 10B , Figure 10C , Figure 10D This is a timing diagram illustrating an example of the operation of transceiver system 1 when simultaneously adjusting using the second mode as a specific mode during periods of no signal. Figure 10A This is a timing diagram showing the optical signal output from the laser diode 12 on the transceiver 11 side. Figure 10B This is a timing diagram showing the average current signal output from photodiode 23 on the transceiver 21 side. Figure 10C This is a timing diagram showing the optical signal output from the laser diode 22 on the transceiver 21 side. Figure 10D The timing diagrams represent the average current signal output from photodiode 13 on the transceiver 11 side. The waveforms of each signal are schematically shown in these timing diagrams.

[0089] In the first cycle P1, the photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12. Figure 10A The average value of the current signal output from the photodiode 23 is obtained by the average current detection unit 67. (23) ()( Figure 10BThe target value is compared with the target value TGb. The target value is the center of amplitude of the optical signal pulse output from laser diode 12. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 23 during a specific mode output period is compared with the target value TGb. (23) ()( Figure 10B ) is greater than the target value TGb (TGb < Iave) (23) During the entire period T1 (excessive optical signal output information) dependent on this result, a specific mode of current signal is input from the drive unit 62 to the laser diode 22, and a specific mode of optical signal is output from the laser diode 22. Figure 10C The target value is TGc, which is the center of the amplitude of the optical signal pulse output from laser diode 22.

[0090] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22. Figure 10C The average value of the current signal output from the photodiode 13 is obtained by the average current detection unit 57. (13) ()( Figure 10D The current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. (13) ()( Figure 10D Smaller than the target value TGd (Iave) (13) <TGd), corresponding to this result (excessive optical signal output), during the entire period T2 of the next second cycle P2, a specific mode current signal is input from the drive unit 52 to the laser diode 12, and a specific mode optical signal is output from the laser diode 12. Figure 10A ).

[0091] Based on the light signal received by photodiode 13 in the first period P1 ( Figure 10C The length of period T1 of a specific mode of ) means that the magnitude of the current signal input from the drive unit 52 to the laser diode 12 in the next second cycle P2 is smaller than that in the first cycle P1. Furthermore, based on the light signal received by the photodiode 23 in the first cycle P1 ( Figure 10A The length of the specific mode period T2, in the following second cycle P2, the magnitude of the current signal input from the drive unit 62 to the laser diode 22 is greater than the current signal in the case of the first cycle P1. Figure 10C ).

[0092] In the second cycle P2, the photodiode 23 on the transceiver 21 side receives the optical signal output from the laser diode 12. Figure 10A The average value of the current signal output from the photodiode 23 is obtained by the average current detection unit 67.(23) ()( Figure 10B The current signal output from photodiode 23 during a specific mode output period is compared with the target value TGb. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 23 during a specific mode output period is compared with the target value TGb. (23) ()( Figure 10B ) is less than the target value TGb(Iave) (23) <TGb), during the entire period T2 (light signal output too small information) that depends on this result, a specific mode of current signal is input from the drive unit 62 to the laser diode 22, and a specific mode of light signal is output from the laser diode 22. Figure 10C ).

[0093] The photodiode 13 on the transceiver 11 side receives the optical signal output from the laser diode 22. Figure 10C The average value of the current signal output from the photodiode 13 is obtained by the average current detection unit 57. (13) ()( Figure 10D The current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. In the example shown in the figure, the average value (Iave) of the current signal output from photodiode 13 during a specific mode output period is compared with the target value TGd. (13) ()( Figure 10D ) is greater than the target value TGd (TGd < Iave) (13) Corresponding to this result, during the entire period T1 of the next third cycle, a current signal of a specific mode is input from the drive unit 52 to the laser diode 12, and a light signal of a specific mode is output from the laser diode 12.

[0094] Based on the light signal received by photodiode 13 in the second period P2 ( Figure 10C The length of period T2 in the specific mode (information that the optical signal output is too small) means that the magnitude of the current signal input from the drive unit 52 to the laser diode 12 in the next third cycle is larger than the current signal in the case of the second cycle P2. Furthermore, in the second cycle P2, based on the optical signal received by the photodiode 23 (the optical signal output from the laser diode 12)... Figure 10A The length of the period T2 of the specific mode is such that the magnitude of the current signal input from the drive unit 62 to the laser diode 22 in the next third cycle is greater than the current signal in the case of the second cycle P2.

[0095] exist Figures 7A to 10DIn any of the illustrated operation examples, the operations after the third cycle are performed in the same manner. The length of the period T1 of a specific mode in the optical signal output from the laser diode 22 when the average value of the current signal output from the photodiode 23 is greater than the target value is different from the length of the period T2 of the specific mode when the average value of the current signal is less than the target value. That is, the length of the period of a specific mode in the optical signal output from the laser diode 22 depends on the average value of the current signal output from the photodiode 23 (Iave). (23) The value depends on the average power of the optical signal output from the laser diode 12. During this period, the lengths of T1 and T2 are preferably more than twice, and more preferably more than ten times.

[0096] We can assume that the optical loss in the optical path of the optical signal from laser diode 12 to photodiode 23 is constant. Therefore, the average value of the current signal output from photodiode 23 (Iave) (23) The target value for comparison can correspond to the target value of the average power of the optical signal output from the laser diode 12. By making the adjustments described above, the average power of the optical signal output from the laser diode 12 can be made close to the target value, and the magnitude of the current signal supplied from the drive unit 52 to the laser diode 12 can be appropriately set based on the signal (voltage signal) that should be transmitted.

[0097] The adjustment of the magnitude of the current signal supplied from the drive unit 52 to the laser diode 12 can be stopped after a predetermined number of cycles, or the adjustment can be stopped when the average value of the current signal output from the photodiode 23 changes compared with the target value. Similarly, the magnitude of the current signal supplied from the drive unit 62 to the laser diode 22 can also be appropriately set.

[0098] exist Figures 7A to 7D as well as Figures 9A to 9D In the illustrated example, the optical signal of a specific mode is a first mode in which the power is repeatedly increased or decreased around the power before and after the period of that specific mode. In this case, during the no-signal period, the time variation of the magnitude of the current signal output from photodiodes 13 and 23 is small, so the amplifiers 55 and 65 can always cancel the DC bias, and can quickly start up when transitioning from the no-signal period to the normal communication period.

[0099] Figures 8A to 8D as well as Figures 10A to 10D The illustrated example is a second mode where the power of the optical signal of a specific mode differs from the power before and after the period of that specific mode. In this case, power consumption can be reduced during periods other than the specific mode output period in the absence of a signal.

[0100] During periods without a signal, when adjusting the magnitude of the current signal supplied to laser diodes 12 and 22, the average current detection units 57 and 67 only need to detect the average magnitude of the current signal output from photodiodes 13 and 23. Similarly, the received signal detection units 58 and 68 only need to detect the average amplitude of the differential signal output from amplification units 55 and 65. High speed is not required in either case. Therefore, during periods without a signal, when adjusting the magnitude of the current signal supplied to laser diodes 12 and 22, the jitter that occurs during high-speed communication in normal communication periods will not be a problem.

[0101] As explained above, the first transceiver 11 described above is a transceiver device used for bidirectional communication, comprising: a drive unit 52 for a laser diode; an amplification unit 55 connected to a photodiode 13; an average current detection unit 57 connected to the photodiode 13; and a control unit 51. During normal communication, a data signal is input to the drive unit 52. During signal-free periods (periods when no data signal is input), a check mode signal is output from the drive unit 52 as a specific mode. During signal-free periods when no data communication is performed, the control unit 51 drives the laser diode 12 by the drive unit 52, thereby receiving a value from the average current detection unit 67 connected to other photodiodes 23 of the other transceiver 21, which includes the offset of the output power of the laser diode 12 from the target value. Figure 7B , Figure 8B , Figure 9B , Figure 10B The associated information (the output period of the optical signal T1) of the signal ( Figure 7C , Figure 8C , Figure 9C , Figure 10C In the case of [the above], based on this information, the magnitude of the current signal supplied from the drive unit 52 to the laser diode 12 is adjusted. The second transceiver 21 has the same structure as the first transceiver 11 and can perform the same function.

[0102] like Figure 5As shown, each of the above-described transceiver devices includes an average current detection unit 57 (67) comprising: a low dropout regulator (71, 72, 73) connected to a photodiode 13 (23); a current mirror circuit (72, 74) including a transistor 72 constituting the low dropout regulator; and a comparator 76 connected to the output side of the current mirror circuit. Control units 51 and 61 are connected to the output terminals of each comparator 76, and adjust the output of the drive units 52 and 62 for the laser diode based on the comparison results. The output terminals of each control unit 51 and 61 can be connected to the output adjustment terminals (bias adjustment terminals or gain adjustment terminals) of each drive unit 52 and 62 (amplifier). Of course, in order to generate a desired mode signal for inspection, the output terminals of the control units 51 and 61 can also be connected to a specific mode generation unit 53, but the mode signal can also be generated internally within the control unit.

[0103] In addition, the average value of the current signal detected by the average current detection unit 57 ( Figure 8D , Figure 9D , Figure 10D The output of the optical signal from the laser diode 12 is correlated with the output of the optical signal. This is because if the output of the optical signal is higher than the target value, the optical signal level input to the average current detection unit 67 on the other side becomes lower. Based on this information (e.g., optical signal output too high information), the optical signal output of the laser diode 22 on the other side changes, and the average current detection unit 57 on its own side is then input to the control unit 51. When this information (e.g., optical signal output too high information) is input to the control unit 51, the average intensity level and duration of the optical signal pulses dependent on this information can be set in the next cycle to make the optical signal output approach the target value.

[0104] The control unit 51 can operate within a period (T1) that depends on the length of the average value of the current signal detected by the average current detection unit 57. Figure 9A ) or T2( Figure 10A During the entire period, a current signal of a specific mode is input from the drive unit 52 on its own side to the laser diode 12, and a light signal of a specific mode is output from the laser diode 12.

[0105] In addition to the average intensity level of the optical signal pulse, the duration of the optical signal pulse is also a factor that causes the average output from photodiode 23 to increase or decrease. If the average output is too high, in the next cycle, to reduce the average output, the average intensity level of the optical signal pulse is reduced. However, this is considered in the cases where the duration of the optical signal pulse in the next cycle is set to a short first period (T1) and a long second period (T2). Figure 9A In the second period P2, the first period T1 is set, in Figure 10A The second period T2 is set in the second period P2. If the center value of the amplitude of the optical signal intensity is reduced and the duration is decreased, the average intensity level decreases significantly; however, if the duration is not changed, the average intensity level decreases only slightly. The amount of reduction can also be adjusted according to the target change in the average intensity level. It should also be noted that the above transceiver system uses feedback control based on binary (high level, low level) outputs from the comparator of the average current detection unit, but transceiver systems that output continuous values ​​from the average current detection unit are also considered.

[0106] The transceiver system 1 described above includes a first terminal device 10 and a second terminal device 20. The first terminal device 10 includes a transceiver device 11, a laser diode 12, a photodiode 13, and a connector 14. The second terminal device 20 includes a transceiver device 21, a laser diode 22, a photodiode 23, and a connector 24. The laser diode 12 and photodiode 23 are optically connected via a first optical fiber 30. The laser diode 22 and photodiode 13 are optically connected via a second optical fiber 40. The transceiver device 11 includes a control unit 51, a drive unit 52, a specific pattern generation unit 53, a transmit signal detection unit 54, an amplification unit 55, a differential amplification unit 56, an average current detection unit 57, and a receive signal detection unit 58. The transceiver device 21 includes a control unit 61, a drive unit 62, a specific pattern generation unit 63, a transmit signal detection unit 64, an amplification unit 65, a differential amplification unit 66, an average current detection unit 67, and a receive signal detection unit 68.

[0107] In addition, the first average current detection unit 57 ( Figure 5 The second average current detection unit 67 includes a differential amplifier 71, a PMOS transistor 72, a capacitor 73, a PMOS transistor 74, a resistor 75, and a comparator 76. The second average current detection unit 67 is constructed by replacing photodiode 13 with photodiode 23 and connecting to... Figure 5 The construction of its elements.

Claims

1. A transceiver device that bidirectionally transmits and receives signals with a counterpart transceiver device, the transceiver device comprising: The driving unit, based on the signal to be sent to the other party's transceiver device, inputs a current signal into the laser diode, so that the laser diode outputs an optical signal to the other party's photodiode on the other party's transceiver device side; The amplification section receives a current signal output from a photodiode, converts the current signal into a voltage signal, and outputs the voltage signal. The photodiode receives an optical signal from a laser diode on the other party's transceiver side. An average current detection unit detects the average value of the current signal output from the photodiode; and The control unit controls the input of the current signal from the driving unit to the laser diode. During a signal-free period when there is no signal to be transmitted or received between the control unit and the other transceiver device, the control unit inputs a current signal from the drive unit to the laser diode, causing the laser diode to output an optical signal. When a specific pattern of optical signal output from the other laser diode arrives at the photodiode during the entire period, the length of which depends on the average value of the current signal output from the other photodiode that receives the optical signal, the control unit adjusts the magnitude of the current signal input from the drive unit to the laser diode based on the length of the period of the specific pattern of optical signal.

2. The transceiver device according to claim 1, wherein, The length of the period depends on the entire period of the average value of the current signal detected by the average current detection unit, so that a current signal of a specific pattern is input from the driving unit to the laser diode, and a light signal of a specific pattern is output from the laser diode.

3. The transceiver device according to claim 1, wherein, The power of the optical signal in the specific mode is repeatedly increased or decreased, centered on the power before and after the period of the specific mode.

4. The transceiver device according to claim 1, wherein, The optical signal of the specific mode has a power that differs from the power before and after the period of that specific mode.

5. The transceiver device according to claim 1, wherein, The average current detection unit includes: A low-dropout (LDO) regulator connected to the photodiode; Includes a current mirror circuit comprising the transistor constituting the low dropout (LDO) regulator; and A comparator connected to the output side of the current mirror circuit.

6. A terminal device comprising: The transceiver device according to claim 1; The laser diode receives a current signal from the driving section of the transceiver and outputs an optical signal. as well as The photodiode receives optical signals and outputs current signals to the amplification section of the transceiver.

7. A transceiver system, comprising: The transceiver device according to claim 1; and The other party's transceiver device. The first terminal device including the transceiver includes: The laser diode receives a current signal from the driving section of the transceiver and outputs an optical signal; and The photodiode receives optical signals and outputs current signals to the amplification section of the transceiver. The second terminal device including the other party's transceiver device comprises: The counterpart laser diode receives a current signal from the driving section of the counterpart transceiver and outputs an optical signal; and The other party's photodiode receives optical signals and outputs current signals to the amplification section of the other party's transceiver. The second terminal device's photodiode receives the optical signal output from the first terminal device's laser diode. The photodiode of the first terminal device receives the optical signal output from the laser diode of the second terminal device.

8. The transceiver system according to claim 7, wherein, The transceiver system also features: The first optical fiber guides the optical signal output from the laser diode of the first terminal device to the photodiode of the counterpart of the second terminal device. as well as The second optical fiber guides the optical signal output from the laser diode of the second terminal device to the photodiode of the first terminal device.

9. A transceiver device used in bidirectional communication. The transceiver includes: Driver unit for laser diodes; Amplification section connected to the photodiode; The average current detection unit connected to the photodiode; and Control Department During signal-free periods when no data communication is performed, the control unit drives the laser diode by the driving unit, thereby adjusting the magnitude of the current signal supplied from the driving unit to the laser diode based on the length of the duration of the specific pattern of the optical signal when the photodiode receives a specific pattern of optical signal from other photodiodes of other transceivers. The length of the duration of the specific pattern of optical signal depends on information output from other average current detection units connected to the other photodiodes, which is associated with the offset of the target value of the output power of the laser diode.

10. The transceiver according to claim 9, wherein, The average current detection unit includes: A low-dropout (LDO) regulator connected to the photodiode; Includes a current mirror circuit comprising the transistor constituting the low dropout (LDO) regulator; and A comparator connected to the output side of the current mirror circuit.

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