JP2011018681A - Optical module, and method of manufacturing optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To match an impedance of a first circuit and an impedance of a second circuit with each other, in the optical module including: a laser module; and a high-frequency circuit including the first circuit connected to the laser module, the second circuit connected to a ground and a differential output circuit which differentially outputs a high-frequency signal to the first circuit and the second circuit.SOLUTION: A control part 15 acquires an amount of variation of electric power consumed by a part including a terminal variable resistor 25 of the high frequency circuit including the first circuit 11, second circuit 12 and differential output circuit 13 when the impedance of the second circuit 12 varies. Then the control part 15 adjusts electric resistance of the terminal variable resistor 25 on the basis of the acquired amount of variation so as to adjust the impedance of the second circuit 12.

Description

  The present invention relates to an optical module and a method for manufacturing the optical module.

  A laser module, a first circuit connected to the laser module, a second circuit grounded to the ground, and a differential output circuit for differentially outputting a high-frequency signal to the first circuit and the second circuit; An optical module including a high-frequency circuit including According to such an optical module, a high frequency signal is converted into an optical signal and output.

  FIG. 5 shows an example of such an optical module. As shown in the figure, the optical module includes a laser module 100, a high-frequency circuit including a first circuit 101 connected to the laser module, a second circuit 102 grounded to the ground, and a differential output circuit 103. ,including.

  The laser module includes either or both of a laser element and a modulator that modulates laser light output from the laser element. The laser module modulates the laser light in accordance with the high frequency signal input from the first circuit 101.

  The differential output circuit 103 differentially outputs a high-frequency signal for modulating laser light to the first circuit 101 and the second circuit 102. For example, the differential output circuit 103 amplifies the differentially input high frequency signal and then outputs the high frequency signal to the first circuit 101 and the second circuit 102.

  For example, as shown in FIG. 5, the first circuit includes a power source 104, a resistor 105, a capacitor 106 that cuts off a direct current component, a resistor 107, and a current source 108 that applies a bias current. These are connected by a signal line, and a high frequency signal is output to the laser module.

  For example, as shown in FIG. 5, the second circuit includes a power source 109, a resistor 110, a capacitor 111 that cuts off a direct current component, and a termination resistor 112 that is grounded to the ground. These are connected by a signal line, and a high frequency signal is output to the ground.

  In Patent Document 1 below (particularly FIG. 1), the transmission-side circuit IC1 (corresponding to a differential output circuit) does not differentially output a high-frequency signal to two circuits, but outputs a single phase to one circuit. A module is disclosed.

JP 2008-160389 A

  In the optical module shown in FIG. 5, the impedance of the first circuit 101 and the impedance of the second circuit 102 may not be matched due to manufacturing variations, laser module drive conditions such as bias voltage, drive amplitude, and duty ratio. is there. In this case, reflection of the high-frequency signal occurs at the ground, and the waveform of the high-frequency signal output from the differential output circuit 103 to the first circuit 101 deteriorates due to the reflection.

  The present invention provides a differential output of a high frequency signal to a laser module, a first circuit connected to the laser module, a second circuit grounded to ground, and the first circuit and the second circuit. In an optical module including a high-frequency circuit including a differential output circuit, an object is to match the impedance of a first circuit and the impedance of a second circuit.

  In order to solve the above problems, an optical module according to the present invention includes a laser module, a first circuit connected to the laser module, a second circuit grounded to ground, the first circuit, A high-frequency circuit including a differential output circuit that differentially outputs a high-frequency signal to the second circuit, wherein the high-frequency circuit is consumed according to reflection of the high-frequency signal from the ground Based on the change amount acquired by the acquisition means, an acquisition means for acquiring a change amount of power consumed when the impedance of the second circuit changes in a portion including a circuit element in which power changes, Adjusting means for adjusting the impedance.

  In one aspect of the present invention, the acquisition unit may acquire a change amount of power consumed when an impedance of the second circuit changes in the differential output circuit. Here, the second circuit includes at least one resistor in at least a part thereof, and the adjusting unit adjusts an electric resistance of any of the at least one resistor for adjusting the impedance. You may do it. In this case, the at least one resistor includes a termination resistor grounded to the ground, and the adjusting means adjusts an electric resistance of the termination resistor for adjusting the impedance. Also good.

  In the aspect of the invention, the second circuit includes at least one resistor in at least a part thereof, and the acquisition unit includes the second circuit in any of the at least one resistor. The amount of change in power consumed when the impedance changes may be acquired, and the adjusting means may adjust the electrical resistance of any of the at least one resistor for adjusting the impedance. . Here, the at least one resistor includes a termination resistor grounded to the ground, and the acquisition unit is configured to reduce power consumed when an impedance of the second circuit changes in the termination resistor. The amount of change may be acquired, or the adjustment unit may adjust the electric resistance of the termination resistor for adjusting the impedance.

  In order to solve the above problems, an optical module manufacturing method according to the present invention includes a laser module, a first circuit connected to the laser module, a second circuit grounded to a ground, and the first A high-frequency circuit including a differential output circuit that differentially outputs a high-frequency signal to the first circuit and the second circuit, wherein the high-frequency circuit is connected to the ground at the ground. An acquisition step of acquiring a change amount of power consumed when an impedance of the second circuit changes in a portion including a circuit element whose power consumption changes according to reflection of the high-frequency signal; and An adjustment step of adjusting the impedance based on the obtained change amount.

It is a figure which shows an example of a structure of the optical module which concerns on embodiment of this invention. It is a flowchart which shows an example of the process performed with the optical module which concerns on embodiment of this invention. It is a figure which shows the relationship between the impedance of a 2nd circuit, and the electric power consumed with a termination | terminus variable resistor. It is a figure which shows an example of a structure of the optical module which concerns on embodiment of this invention. It is a figure for demonstrating a prior art.

[Constitution]
FIG. 1 is a diagram illustrating an example of a configuration of an optical module 1 according to an embodiment of the present invention. As shown in the figure, the optical module 1 includes a laser module 10, a first circuit 11 connected to the laser module 10, a second circuit 12 grounded to the ground, and a differential output circuit 13. And a thermocouple 14 and a control unit 15.

  The laser module includes one or both of a laser element and a modulator that modulates laser light output from the laser element. The modulator is, for example, an EA modulator or a Mach-Zehnder interferometric modulator. . The laser module modulates the laser light in accordance with the high frequency signal input from the first circuit 11.

  The differential output circuit 13 differentially outputs a high frequency signal for modulating the laser beam to the first circuit 11 and the second circuit 12. For example, the differential output circuit 13 amplifies the differentially input high frequency signal and then outputs the high frequency signal to the first circuit 11 and the second circuit 12.

  The first circuit 11 includes a DC power supply 16, a resistor 17, a capacitor 18 that blocks a DC current component, a resistor 19, and a current source 20 that applies a bias current. These are connected by signal lines. The high-frequency signal input by the differential output circuit 13 is output to the laser module 10 through the signal line.

  The second circuit 12 includes at least one resistor in at least a part thereof. Here, the second circuit 12 includes a resistor in a part thereof. That is, the second circuit 12 includes a DC power source 21, a variable resistor 22 (resistor), a coil 23 that cuts off an alternating current component, a capacitor 24 that cuts off a direct current component, and a termination variable resistor 25 that is grounded. (Resistor, termination resistor), and two resistors (variable resistor 22 and termination variable resistor 25) are included in a part thereof. These are connected by signal lines. The high-frequency signal input by the differential output circuit 13 is output to the ground through the signal line. Note that the second circuit 12 may include only the termination variable resistor 25 at least in part.

  When the impedance of the first circuit 11 and the impedance of the second circuit 12 are not matched, the high-frequency signal is reflected by the ground. In this case, the power corresponding to the reflected signal is consumed by circuit elements (hereinafter referred to as specific circuit elements) such as the termination variable resistor 25, the variable resistor 22, and the differential output circuit 13, so that the second circuit 12 When the impedance changes, the power consumed by each specific circuit element also changes. As a result, when the impedance of the second circuit 12 changes, the power consumed in the portion including the specific circuit element of the high-frequency circuit also changes.

  For example, when reflection occurs, the apparent load on the second circuit 12 increases according to the reflection. Therefore, in the differential output circuit 13 that operates so as to maintain a predetermined output amplitude, power corresponding to the reflection is consumed. Therefore, when the impedance of the second circuit 12 changes, the power consumed by the differential output circuit 13 also changes.

  The thermocouple 14 is used to acquire the amount of change in power consumption of a specific circuit element when the impedance of the second circuit 12 changes. In the case of the present embodiment, the thermocouple 14 is installed in the termination variable resistor 25 in order to obtain the amount of change in power consumed by the termination variable resistor 25 when the impedance of the second circuit 12 changes. The temperature of the variable resistor 25 is detected.

  The control unit 15 is, for example, a microcomputer that operates according to a predetermined program. A signal indicating the temperature detected by the thermocouple is input to the control unit 15.

[processing]
FIG. 2 is a flowchart of processing repeatedly performed in the optical module 1 when the differential output circuit 13 outputs a high-frequency signal differentially. This process is performed, for example, when the control unit 15 operates according to a predetermined program. By this processing, the impedance of the first circuit 11 and the impedance of the second circuit 12 are matched so that the high frequency is not reflected at the ground.

  That is, the control unit 15 (acquisition means) acquires the change amount ΔP of power consumed by any one of the specific circuit elements (that is, the variable resistor 22 and the termination variable resistor 25) included in the second circuit 12. To do. Here, the control unit 15 acquires the change amount ΔP of the power consumed by the termination variable resistor 25 based on the change amount of the temperature of the termination variable resistor 25 detected by the thermocouple 14 (S101). In addition, after installing the thermocouple 14 in the variable resistor, the control unit 15 is made to acquire the change amount ΔP of the power consumed by the variable resistor 22 based on the change amount of the temperature detected by the thermocouple 14. You may do it.

  And the control part 15 (adjustment means) adjusts the impedance of the 2nd circuit 12 based on variation | change_quantity (DELTA) P (S102-S103).

  That is, the control unit 15 determines whether or not the change amount ΔP is equal to or less than the predetermined value Pth (S102). Here, the case where the change amount ΔP is equal to or less than the predetermined value Pth is a case where the reflection of the high-frequency signal at the ground is small, in other words, the impedance of the first circuit 11 and the impedance of the second circuit 12 are almost matched. This is the case.

  FIG. 3 shows the relationship between the impedance of the second circuit 12 (“R” in FIG. 3) and the power consumption (P in FIG. 3) at the termination variable resistor 25 or the variable resistor 22. As shown in the figure, when the power consumption is near the minimum point, ΔP when the impedance of the second circuit 12 changes is small. Therefore, when ΔP is small, it is considered that the reflection of the high-frequency signal from the ground is small, and therefore, the impedance of the first circuit 11 and the impedance of the second circuit 12 are considered to be matched.

  Therefore, when ΔP is equal to or less than the predetermined value Pth (Y in S102), it is considered that the power consumption is near the minimum point and the impedance of the first circuit 11 and the impedance of the second circuit 12 are matched. The unit 15 ends the process.

  On the other hand, when ΔP is larger than the predetermined value Pth (N in S102), it is considered that the reflection of the high-frequency signal on the ground is large, so that the specific circuit included in the second circuit 12 is used for adjusting the impedance of the second circuit 12. Adjust the electrical resistance of any of the elements (ie, variable resistor 22 and termination variable resistor 25). In the present embodiment, the control unit 15 adjusts the electrical resistance of the termination variable resistor 25 in order to adjust the impedance of the second circuit 12 (S103). In order to adjust the impedance, the electric resistance of the variable resistor 22 may be adjusted, or the electric resistances of both the variable resistor 22 and the terminating variable resistor 25 may be adjusted.

  As a result of the step of S103, the power consumed by the termination variable resistor 25 changes, and the change amount ΔP is acquired in the next step of S101.

[Summary]
As described above, in the optical module 1, the impedance of the first circuit and the impedance of the second circuit are matched by the process shown in FIG.

  The embodiment of the present invention is not limited to the above embodiment.

[Modification 1]
For example, when the impedance of the second circuit 12 changes, the power consumed by the differential output circuit 13 (specific circuit element) changes. Therefore, the relationship between the impedance of the second circuit 12 and the power consumption of the differential output circuit 13 is the same as the relationship shown in FIG.

  Therefore, the control unit 15 (acquisition means) does not acquire the amount of change in power consumption of the variable resistor 22 or the termination variable resistor 25 in step S101, but the amount of change in power consumption of the differential output circuit 13. May be obtained.

  FIG. 4 is a diagram illustrating an example of the configuration of the optical module 1 according to the first modification. As shown in the figure, in the first modification, when the impedance of the second circuit 12 changes, it is supplied to the differential output circuit 13 in order to obtain the change amount ΔP of power consumed by the differential output circuit 13. A shunt resistor 26 is installed between the power supply (Vcc in FIG. 4) and the differential output circuit 13, and a converter 27 that converts information indicating the potential difference of the shunt resistor 26 into a digital signal is installed. On this basis, the control unit 15 acquires ΔP based on the amount of change in the potential difference of the shunt resistor 26 in step S101. Also in the first modification, the impedance of the first circuit 11 and the impedance of the second circuit 12 are matched by the processing shown in FIG.

[Modification 2]
For example, the present invention can be used when manufacturing the optical module 1 such that the impedance of the first circuit 11 and the impedance of the second circuit 12 are matched.

  In this case, the manufacturer of the optical module 1 causes the differential output circuit 13 to differentially output a high-frequency signal on a trial basis, and causes the control unit 15 to repeatedly execute the process shown in FIG. 2 until ΔP becomes Pth or less. By this method, the manufacturer manufactures the optical module 1 so that the impedance of the first circuit 11 and the impedance of the second circuit 12 are matched. Note that the manufacturer adjusts the impedance of the second circuit 12 by executing the process shown in FIG. 2, and then controls the optical module 1 to the control unit 15 and the thermocouple 14 (in the case of the first modification, the control unit 15 and the shunt resistor). Device 26 and converter 27) may be removed.

[Others]
For example, the laser module 10 may not have a modulator. In this case, the laser beam output from the laser element is modulated by the forward current applied to the laser element without passing through the modulator. Further, the laser module 10 may include a laser element module including a laser element and a modulator module including a modulator as separate bodies. In this case, the laser element module and the modulator module are connected by an optical fiber, and the laser light output from the laser element is modulated by the modulator.

  DESCRIPTION OF SYMBOLS 1 Optical module, 10 Laser module, 11 1st circuit, 12 2nd circuit, 13 Differential output circuit, 14 Thermocouple, 15 Control part, 16, 21 DC power supply, 17, 19 Resistor, 18, 24 Capacitor, 20 Current source, 22 variable resistor, 23 coil, 25 termination variable resistor, 26 shunt resistor, 27 converter.

Claims (8)

A laser module, a first circuit connected to the laser module, a second circuit grounded to ground, and a differential output for differentially outputting a high-frequency signal to the first circuit and the second circuit An optical module including a high-frequency circuit including a circuit,
Obtaining the amount of change in power consumed when the impedance of the second circuit changes in a portion of the high-frequency circuit that includes a circuit element whose power consumption changes in response to reflection of the high-frequency signal at the ground. Acquisition means to
Adjusting means for adjusting the impedance based on the amount of change acquired by the acquiring means;
An optical module comprising: The acquisition means includes
Obtaining the amount of change in power consumed when the impedance of the second circuit changes in the differential output circuit;
The optical module according to claim 1. The second circuit includes at least one resistor in at least a portion thereof;
The adjusting means includes
Adjusting the electrical resistance of any of the at least one resistor to adjust the impedance;
The optical module according to claim 2. The at least one resistor includes a termination resistor grounded to the ground;
The adjusting means includes
Adjusting the electrical resistance of the termination resistor to adjust the impedance;
The optical module according to claim 3. The second circuit includes at least one resistor in at least a part thereof;
The acquisition means includes
Obtaining the amount of change in power consumed when the impedance of the second circuit changes in any of the at least one resistor;
The adjusting means includes
Adjusting the electrical resistance of any of the at least one resistor to adjust the impedance;
The optical module according to claim 1. The at least one resistor includes a termination resistor grounded to the ground;
The acquisition means includes
Obtaining the amount of change in power consumed when the impedance of the second circuit changes in the termination resistor;
The optical module according to claim 5. The adjusting means includes
Adjusting the electrical resistance of the termination resistor to adjust the impedance;
The optical module according to claim 6. A laser module, a first circuit connected to the laser module, a second circuit grounded to ground, and a differential output for differentially outputting a high-frequency signal to the first circuit and the second circuit A high frequency circuit including a circuit, and an optical module manufacturing method including:
Obtaining the amount of change in power consumed when the impedance of the second circuit changes in a portion of the high-frequency circuit that includes a circuit element whose power consumption changes in response to reflection of the high-frequency signal at the ground. An acquisition step to
An adjustment step of adjusting the impedance based on the amount of change acquired in the acquisition step;
The manufacturing method of the optical module characterized by including.

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