Optical module

Abstract

This optical module is provided with: a temperature regulator (2) that performs a function of regulating the temperature of a semiconductor laser (5); and an optical monitor (6) that functions to monitor the optical output and the oscillation wavelength from the semiconductor laser (5). And a heater (7) and a thermistor (8) housed in the package (1). The heater (7) and the thermistor (8) are electrically connected in parallel, and one end of the heater (7) and one end of the thermistor (8) are connected to the heater and thermistor common pin (P7).

Description

Technical Field

[0001] The present disclosure relates to an optical module. Background Art

[0002] In order to increase the capacity of optical communication systems and the like, optical communication modules used in optical communication systems and the like are desired to be more advanced.

[0003] Advanced optical communication modules require not only current to be supplied to semiconductor lasers but also numerous other functions such as a temperature monitor or temperature regulator for temperature control, an optical output monitor, and an oscillation wavelength monitor.

[0004] For example, Patent Document 1 discloses a laser module that houses a laser (LD), a light receiving element (PD) for monitoring light emitted from the rear end face of the laser, a light receiving element (PD) for monitoring light emitted from the rear end face of the laser and transmitted through an etalon, a thermistor for detecting the temperature of the laser, and a first Peltier element and a second Peltier element, each of which has a terminal for applying current and is connected in series or in parallel to a pair of input terminals for external signals provided in the module.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-69130

[0006] The laser module shown in Patent Document 1 has eight terminals for exchanging electrical signals between the inside and outside of the package in a perspective view showing the main structure in more detail, but their relationship with the components housed inside the package is not shown.

[0007] In addition to the two input terminals for the first and second Peltier elements, judging from the schematic diagram showing the structure, at least six terminals are required, including terminals for the laser, two light-receiving elements, thermistor, and a ground terminal.

[0008] On the other hand, optical communication modules are expected to be more advanced by adding more functions, and are also expected to be more compact.

[0009] The miniaturization of optical communication modules is also limited by the number of terminals for exchanging electrical signals between the inside and outside of the package. Summary of the Invention

[0010] The present disclosure has been made in view of the above-mentioned points, and an object thereof is to achieve miniaturization of an optical module including a semiconductor laser, that is, an optical module including a heater and a thermistor inside a package.

[0011] The optical module involved in this disclosure has:

[0012] The package body is composed of a base and a cylindrical window cover fixed with an opening end surface of the side wall portion in contact with and fixed to the peripheral end portion of the inner plane of the base;

[0013] A semiconductor laser is housed in a package and emits laser light from a window with a window cover;

[0014] The optical monitor is housed in the package and receives laser light from the semiconductor laser to monitor the laser light from the semiconductor laser.

[0015] a temperature regulator housed in the package, which controls the temperature of the semiconductor laser and the light monitor to change when the monitoring value from the light monitor deviates from the set monitoring value, thereby regulating the temperature of the semiconductor laser and the light monitor;

[0016] A heater is housed in the package;

[0017] a thermistor housed in the package and electrically connected in parallel with the heater;

[0018] The laser pin passes through the base in an electrically insulated manner and has an electrode of the semiconductor laser connected to an inner lead portion exposed from an inner plane of the base;

[0019] The monitor pin passes through the base in an electrically insulated manner and has an output terminal of the optical monitor connected to an inner lead portion exposed from an inner plane of the base;

[0020] The temperature regulator pin passes through the base in an electrically insulated manner and has an electrode of the temperature regulator connected to an inner lead portion exposed from an inner plane of the base;

[0021] The heater and the thermistor share a pin which passes through the base in an electrically insulated manner, and to which one end of the heater and one end of the thermistor are connected at an inner lead portion exposed from an inner plane of the base; and

[0022] The ground pin is electrically connected to the base.

[0023] According to the present disclosure, by electrically connecting the heater and the thermistor housed in the package in parallel, the pins for the heater and the thermistor are shared, thereby achieving miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a perspective view showing a state in which the cover of the optical module according to the first embodiment is removed.

[0025] Figure 2 This is a perspective view showing the optical module according to the first embodiment.

[0026] Figure 3 yes Figure 1 Sectional view III-III.

[0027] Figure 4 This is a block diagram showing an optical monitor in the optical module according to the first embodiment.

[0028] Figure 5 This is a schematic perspective view showing the optical monitor in the optical module according to the first embodiment.

[0029] Figure 6 This is a schematic block diagram showing the optical module device according to the first embodiment.

[0030] Figure 7 This is a diagram showing a circuit diagram and a relationship between pins of a heater and a thermistor in the optical module according to the first embodiment.

[0031] Figure 8 This is a diagram showing the relationship between the temperature of the thermistor and the parallel resistance value of the heater and the thermistor in the optical module according to the first embodiment.

[0032] Figure 9 This is a diagram showing a circuit diagram of a heater and a thermistor in an optical module according to a reference example, and a relationship between pins.

[0033] Figure 10 This is a graph showing the resistance value of a heater relative to temperature in an optical module according to a reference example.

[0034] Figure 11 This is a diagram showing the relationship between the temperature and the resistance value of the thermistor in the optical module according to the reference example.

[0035] Figure 12 This is a diagram showing a circuit diagram of a heater and a thermistor in an optical module according to a second embodiment, and a relationship between pins.

[0036] Figure 13 This is a diagram showing a circuit diagram of a heater and a thermistor and a relationship between pins in a modified example of the optical module according to the second embodiment. DETAILED DESCRIPTION

[0037] Implementation Method 1

[0038] based on Figures 1 to 8 The optical module according to the first embodiment will be described.

[0039] The optical module according to the first embodiment is suitable for use as a light source module for digital coherent communication.

[0040] The optical module according to the first embodiment is an example of a TO-CAN type optical transmission module suitable for optical communication.

[0041] The optical module according to the first embodiment is an optical module including a single-wavelength semiconductor laser.

[0042] The optical module according to the first embodiment is an optical module having a function of adjusting the temperature of a semiconductor laser and a function of monitoring the optical output and oscillation wavelength from the semiconductor laser.

[0043] Therefore, the following description will be made by taking a TO-CAN type optical transmission module for optical communication including a single wavelength semiconductor laser as an example.

[0044] like Figures 1 to 3 As shown, the optical module involved in embodiment 1 includes a package 1 consisting of a base 11 and a window cover 12 (hereinafter referred to as a cover), a temperature regulator 2, a base 3, a sub-mount for a semiconductor laser (hereinafter referred to as a sub-mount) 4, a semiconductor laser 5, a light monitor 6, a heater 7, a thermistor 8, a plurality of pins P2 to P7 and a grounding pin P1.

[0045] In addition, Figure 1 and Figure 3 In order to avoid complexity, the leads electrically connecting the components 2, 5, 6, 7, and 8 to the pins P1 to P6 are omitted.

[0046] The base 11 is made of a disk-shaped metal. The base 11 is not limited to a disk-shaped one, and may be cylindrical or quadrangular, as long as it is a flat plate having an inner flat surface 11a and an outer flat surface 11b parallel to the inner flat surface 11a.

[0047] The inner plane 11 a of the base 11 is a mounting surface and serves as an area for mounting components.

[0048] In this example, the base 11 is a circular plate-shaped metal with a diameter of 5.6 mm.

[0049] The cover 12 is a metal lens cover formed of a cylindrical metal with one end open, a bottom and a side wall, and an outer diameter slightly smaller than the diameter of the base 11 .

[0050] An opening portion for mounting a flat glass or lens as a window 13 is formed in the center of the bottom of the cover 12 .

[0051] A flat glass or lens serving as the window 13 is bonded and assembled to the bottomed opening by adhesive or fusing so as to maintain airtightness inside and outside the cover.

[0052] The end surface of the side wall portion of the cover 12 is in contact with the peripheral end portion of the inner flat surface 11 a of the base 11 and is joined and fixed to the peripheral end portion by electric welding.

[0053] The interior surrounded by the base 11 and the cover 12 is filled with an inert gas or is in a vacuum state, thereby isolating the semiconductor laser 5 from the outside air and hermetically sealing it.

[0054] The forward laser light Lf from the semiconductor laser 5 is emitted from the window 13 .

[0055] The base 11 and the cover 12 constitute a TO-CAN type package.

[0056] The temperature regulator 2 is housed in a package and mounted on a base 11 .

[0057] The temperature controller 2 has a flat lower surface 2a and a flat upper surface 2b parallel to the lower surface 2a. The lower surface 2a is fixed to the inner plane 11a of the base 11 by solder or a conductive adhesive, while the upper surface 2b serves as the mounting surface. Hereinafter, the upper surface 2b is referred to as the mounting surface.

[0058] The temperature regulator 2 heats or cools the mounting surface 2 b by passing an electric current.

[0059] When the monitoring value from the optical monitor 6 deviates from the set monitoring value, the temperature regulator 2 performs control to change the temperature applied to the semiconductor laser 5 and the optical monitor 6 .

[0060] That is, the temperature regulator 2 regulates the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 .

[0061] The temperature controller 2 is a thermo-electric cooler (TEC) composed of a Peltier element.

[0062] The pedestal 3 is an L-shaped metal component placed on the mounting surface 2b of the temperature regulator 2 and having a planar portion 3a whose upper and lower surfaces are flat surfaces and a vertical portion 3b whose vertical surface is flat and is formed integrally with the planar portion 3a. On the opposite side of the vertical surface of the vertical portion 3b, a step portion having a placing surface 3c serving as a horizontal surface is formed.

[0063] The lower surface of the flat portion 3 a of the pedestal 3 is fixed to the mounting surface 2 b of the temperature regulator 2 by soldering or a conductive adhesive.

[0064] A semiconductor laser 5 is mounted and fixed on the vertical surface of the vertical portion 3 b of the pedestal 3 via a semiconductor laser submount 4 .

[0065] The semiconductor laser 5 is fixed to the vertical surface of the vertical portion 3 b of the pedestal 3 so that the optical axes of the forward laser light Lf and the backward laser light Lb of the semiconductor laser 5 coincide with the central axis of the base 11 .

[0066] The submount 4 is formed of, for example, a base body made of a dielectric material of aluminum nitride (AlN) with a metal wiring layer pattern formed on the surface.

[0067] An optical monitor 6 is mounted and fixed on the upper surface of the flat surface portion 3 a of the pedestal 3 .

[0068] The optical monitor 6 is fixed to the upper surface of the flat portion 3 a of the base 3 so as to receive the backward laser light Lb from the semiconductor laser 5 .

[0069] The light monitor 6 is arranged at an angle capable of receiving the backward laser light Lb from the semiconductor laser 5 .

[0070] For example, if the optical coupler 61 (refer to Figure 4 and Figure 5 ) If the angle at which the maximum coupling efficiency of the rear laser Lb of the semiconductor laser 5 can be obtained is 90 degrees relative to the plane 6a of the optical monitor 6, the optical monitor 6 is configured in the direction of 90 degrees. If the angle is 80 degrees, the optical monitor 6 is configured in the direction of 80 degrees.

[0071] When the angle of the optical monitor 6 relative to the backward laser light Lb of the semiconductor laser 5 is set to 90 degrees, the angle formed by the upper surface of the planar portion 3a of the pedestal 3 and the vertical surface of the vertical portion 3b of the pedestal 3 is set to 90 degrees.

[0072] In addition, when the angle of the light monitor 6 relative to the rear laser Lb of the semiconductor laser 5 is set to 80 degrees, the upper surface of the planar portion 3a in the base 3 can also be tilted so that the angle formed by the upper surface of the planar portion 3a in the base 3 and the vertical surface of the vertical portion 3b in the base 3 is 80 degrees.

[0073] In addition, in embodiment 1, the semiconductor laser 5 is mounted and fixed on the vertical portion 3b of the base 3, and the light monitor 6 is mounted and fixed on the planar portion 3a of the base 3. However, the following configuration relationship may be adopted, that is, the semiconductor laser 5 and the light monitor 6 are housed inside the package 1, the front laser Lf of the semiconductor laser 5 is emitted to the outside of the package 1, and the rear laser Lb of the semiconductor laser 5 can be received by the light monitor 6.

[0074] The thermistor 8 is mounted and fixed on the mounting surface 3 c of the step portion of the pedestal 3 .

[0075] The pedestal 3 transfers heat from the mounting surface 2 b of the temperature regulator 2 to regulate the temperature of the semiconductor laser 5 via the submount 4 , that is, to heat or cool the semiconductor laser 5 .

[0076] At the same time, the pedestal 3 conducts heat from the mounting surface 2 b of the temperature regulator 2 to regulate the temperature of the light monitor 6 , that is, to heat or cool the light monitor 6 .

[0077] Since the semiconductor laser 5 and the optical monitor 6 whose temperature is regulated by the temperature regulator 2 are arranged in the vertical direction through the base 3, the dedicated area occupied by the semiconductor laser 5 and the optical monitor 6 in the mounting surface 2b of the temperature regulator 2 can be reduced. As a result, the temperature regulator 2 can be miniaturized, and the optical module can be miniaturized.

[0078] Furthermore, the thermistor 8 is housed in the package 1 and measures the internal temperature of the package 1 .

[0079] The thermistor 8 is housed in the package 1 in order to perform temperature control by the temperature regulator 2 with high precision and to improve the functionality of the optical module.

[0080] That is, by using thermistor 8 to detect the temperature of semiconductor laser 5 and the temperature of light monitor 6 when preparing to operate the optical module, the relationship between the target value of the monitoring value of the laser light from semiconductor laser 5 and the temperature of semiconductor laser 5 and the temperature of light monitor 6 can be understood with higher accuracy.

[0081] Furthermore, by regularly, periodically, or randomly detecting the temperature of the semiconductor laser 5 and the temperature of the optical monitor 6 using the thermistor 8 when the optical module is operating, the temperature of the semiconductor laser 5 and the temperature of the optical monitor 6 when the optical module is operating can be understood with higher accuracy.

[0082] In this example, the thermistor 8 is mounted and fixed on the mounting surface 3 c of the step portion of the pedestal 3 , and can therefore measure and detect the temperature of the pedestal 3 , that is, the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 .

[0083] In addition, although the thermistor 8 is mounted and fixed on the mounting surface 3c of the step portion of the base 3, it can also be mounted and fixed on a portion of the base 3 other than the mounting surface 3c of the step portion, the mounting surface 2b of the temperature regulator 2, or the inner surface 11a of the base 11.

[0084] In short, the thermistor 8 is housed in the package 1 to measure the internal temperature of the package 1 , and the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 can be detected based on the measurement result.

[0085] The semiconductor laser 5 is a single-wavelength semiconductor laser, a so-called single-mode laser oscillating at a single wavelength. As a single-wavelength semiconductor laser, for example, a distributed feedback (DFB) laser diode element (chip) or a distributed bragg reflector (DBR) laser diode element (chip) can be used.

[0086] The semiconductor laser 5 emits forward laser light Lf from its emission surface and emits backward laser light Lb from its back surface. The forward laser light Lf is used for optical communication, and the backward laser light Lb is monitored.

[0087] The light intensity of such a single-wavelength semiconductor laser varies according to the supplied drive current. The light intensity also varies according to the temperature of the laser itself. Generally, the lower the temperature, the greater the light output.

[0088] Furthermore, the oscillation wavelength of laser light from a single-wavelength semiconductor laser also changes depending on the temperature of the laser. The oscillation wavelength of laser light from a single-wavelength semiconductor laser also changes depending on Joule heat caused by the driving current.

[0089] Therefore, in the first embodiment, the backward laser light Lb from the semiconductor laser 5 is monitored by the optical monitor 6 and the temperature of the semiconductor laser 5 is adjusted by the temperature regulator 2 to maintain the wavelength of the laser light oscillated from the semiconductor laser 5 constant.

[0090] The light monitor 6 outputs a monitoring value for causing the temperature regulator 2 to perform control to change the temperature applied to the semiconductor laser 5 and the light monitor 6 to the control unit 9 (see FIG. 1 ) that controls the temperature regulator 2. Figure 6 ).

[0091] The control unit 9 controls the temperature regulator 2, the semiconductor laser 5, the light monitor 6, and the heater 7. The control unit 9 exchanges signals with the semiconductor laser 5, the light monitor 6, and the temperature regulator 2, respectively, controls the current and voltage flowing to the semiconductor laser 5, the light monitor 6, and the temperature regulator 2, respectively, and controls the light intensity and wavelength of the laser light from the semiconductor laser 5.

[0092] The control unit 9 receives input of the temperature information obtained by the thermistor 8 during preliminary preparation, and receives input of the temperature information obtained by the thermistor 8 regularly, periodically, or randomly during the operation of the optical module.

[0093] The optical monitor 6 measures the light intensity of the rear laser light Lb from the semiconductor laser 5 to obtain an optical power monitoring value Ip and a wavelength monitoring value Iλ, wherein the optical power monitoring value Ip, as one of the monitoring values, is composed of a current value for controlling the value of the driving current flowing to the semiconductor laser 5 so that the optical output of the semiconductor laser 5 becomes a target value, and the wavelength monitoring value Iλ, as one of the monitoring values, is composed of a current value for controlling the value of the current supplied to the temperature regulator 2 so that the wavelength of the laser light from the semiconductor laser 5 becomes a target value.

[0094] The optical monitor 6 constitutes a part of a wavelength locker for controlling the wavelength of the laser light from the semiconductor laser 5 .

[0095] The control section 9 performs the following control: if the optical power monitoring value Ip is greater than the current setting value, which is one of the set monitoring values, the temperature regulator 2 heats the mounting surface 2b according to the value of the supplied current, thereby increasing the temperature imparted to the semiconductor laser 5 and the optical monitor 6; and if the optical power monitoring value Ip is less than the current setting value, the temperature regulator 2 cools the mounting surface 2b according to the value of the supplied current, thereby decreasing the temperature imparted to the semiconductor laser 5 and the optical monitor 6.

[0096] The current setting value is set to, for example, ±10% of a target value Ip_target of the optical power monitor value Ip when a drive current is supplied to the semiconductor laser 5 so that the optical output, ie, the light intensity, of the semiconductor laser 5 reaches a target value.

[0097] If the wavelength monitoring value Iλ / Ip, which is the ratio of the optical power monitoring value Ip to the wavelength monitoring value Iλ, deviates from the wavelength setting value, which is one of the set monitoring values, the temperature regulator 2 changes the temperature of the mounting surface 2b according to the value of the supplied current, thereby changing the temperature applied to the semiconductor laser 5 and the optical monitor 6.

[0098] In this example, the temperature regulator 2 performs the following control: if the wavelength monitoring value Iλ / Ip is greater than the wavelength setting value, the temperature regulator 2 heats the mounting surface 2b according to the value of the supplied current, thereby increasing the temperature imparted to the semiconductor laser 5 and the light monitor 6; if the wavelength monitoring value Iλ / Ip is less than the wavelength setting value, the temperature regulator 2 cools the mounting surface 2b according to the value of the supplied current, thereby decreasing the temperature imparted to the semiconductor laser 5 and the light monitor 6.

[0099] The wavelength setting value is set, for example, to ±10% of the target value Iλ_target of the wavelength monitor value Iλ / Ip when the wavelength λLD of the laser light emitted by the semiconductor laser 5 reaches the target value λ_target.

[0100] like Figure 4 and Figure 5 As shown, the optical monitor 6 includes an optical coupler 61 , a demultiplexer 62 , a first optical receiver 63 , an optical filter 64 , a second optical receiver 65 , and optical waveguides 661 to 665 .

[0101] The optical monitor 6 is, for example, a planar waveguide optical monitor based on a silicon photonic chip formed by integrating an optical coupler 61, a demultiplexer 62, a first optical receiver 63, an optical filter 64, a second optical receiver 65, and optical waveguides 661 to 665 on a plane of a silicon (Si) substrate 6A.

[0102] The optical waveguides 661 to 665 are silicon waveguides formed of silicon.

[0103] The optical coupler 61 receives the backward laser light Lb from the semiconductor laser 5 and couples the backward laser light Lb perpendicularly incident on the plane 6 a of the optical monitor 6 to the optical waveguide 661 .

[0104] The optical coupler 61 is, for example, a grating coupler. Since the grating coupler has the function of coupling the backward laser light Lb from the semiconductor laser 5 arriving from above the plane 6a of the optical monitor 6 to the optical waveguide 661, the plane 6a of the optical monitor 6 and the semiconductor laser 5 are arranged via the pedestal 3 at an angle that maximizes the coupling efficiency of the grating coupler.

[0105] In addition, the optical coupler 61 may also be an elephant coupler.

[0106] Since a grating coupler can increase the number of light modes, it has a characteristic of being less position-dependent than end face coupling of a waveguide. Therefore, a grating coupler is preferably used for the optical coupler 61 of this example.

[0107] The wavelength splitter 62 splits the backward laser light Lb from the semiconductor laser 5 , which is received by the optical coupler 61 and transmitted via the optical waveguide 661 , into two laser lights.

[0108] The branching filter 62 is, for example, any of a directional coupler, a multi-mode interferometer (MMI), and a Y-branch waveguide. In this example, the branching filter 62 is an MMI.

[0109] The first light receiver 63 receives the laser light from one side of the wave splitter 62 after the rear laser light Lb from the semiconductor laser 5 is received by the optical coupler 61 via the optical waveguide 662, performs photoelectric conversion on the received light, and outputs the current corresponding to the rear laser light Lb from the semiconductor laser 5 to the output end as the first monitoring value.

[0110] The first optical receiver 63 directly converts the backward laser light Lb coupled by the optical coupler 61 and the backward laser light Lb from the semiconductor laser 5 into a current, and thus functions as an optical power monitor of the semiconductor laser 5 .

[0111] That is, the current value Ip of the current obtained from the first light receiver 63 is the optical power monitoring value Ip which represents the light output of the laser from the semiconductor laser 5, i.e., the light intensity, using the current value. The first light receiver 63 outputs the optical power monitoring value Ip as the first monitoring value to the output end.

[0112] The first light receiver 63 is a waveguide light receiver or a surface-incident light receiver. In this example, a photodiode, which is a SiGe (silicon germanium) light receiver, is used.

[0113] The optical filter 64 receives the other laser beam that is received by the optical coupler 61 from the semiconductor laser 5 and demultiplexed by the demultiplexer 62 through the optical waveguide 663 .

[0114] The optical filter 64 is a phase-variable optical filter having temperature dependence of wavelength.

[0115] That is, the peak of the wavelength of the laser light output from the optical filter 64 has temperature dependence such that it shifts toward the longer wavelength side as the temperature in the optical filter 64 increases.

[0116] The optical filter 64 is a ring resonator. In this example, the ring resonator is used as a filter having periodic characteristics.

[0117] Furthermore, the optical filter 64 is not limited to the ring resonator filter.

[0118] As the optical filter 64 , a filter having no temperature dependence is ideal.

[0119] However, it is generally difficult to reduce the temperature dependence to zero, and a filter may have a temperature dependence that shifts toward a longer wavelength when the temperature rises, or a filter may have a temperature dependence that shifts toward a shorter wavelength when the temperature rises.

[0120] Instead of the ring resonator filter, a Mach-Zehnder interferometer (MZ interferometer) or a distributed Bragg reflector (DBR) filter may be used.

[0121] In this example, a ring resonator 64 a is used as the optical filter 64 . Hereinafter, the ring resonator 64 a will be referred to as a ring resonator filter.

[0122] The ring resonator filter 64a is composed of an optical waveguide forming a closed loop.

[0123] The optical waveguide 663 connected to the other output end of the splitter 62 is used as the input side, and the optical waveguide 664 connected to the input end of the second optical receiver 65 is used as the output side. The optical waveguide forming a closed loop of the ring resonator filter 64a, the optical waveguide 663 on the input side, and the optical waveguide 664 on the output side continuous with the optical waveguide 663 are coupled to cause resonance in the optical waveguide forming the closed loop, thereby functioning as a filter.

[0124] Furthermore, the ring resonator filter is coupled to another output-side optical waveguide 665 , which is arranged to face the output-side optical waveguide 664 with respect to the ring resonator filter 64 a .

[0125] The optical waveguide forming a closed loop constituting the ring resonator filter 64 a is a silicon waveguide formed of silicon.

[0126] The diameter of the optical waveguide forming the closed loop is approximately 100 μm, which is very small, and thus can be miniaturized. Furthermore, the influence of the temperature gradient due to the ambient temperature on the ring resonator filter 64 a can be suppressed.

[0127] As the second light receiver 65, either a photodiode 65a is used, which is connected to, i.e., coupled to, the ring resonator filter 64a via an output-side optical waveguide 664 and receives light transmitted from the ring resonator filter 64a; or a photodiode 65b is used, which is connected to, i.e., coupled to, the ring resonator filter 64a via another output-side optical waveguide 665 arranged opposite to the optical waveguide 664 and receives light transmitted from the ring resonator filter 64a.

[0128] As is well known, since the optical waveguide 664 on the output side and the optical waveguide 665 on the other output side are arranged opposite to each other relative to the ring resonator filter 64a, the intensity of the current flowing through the photodiode 65a connected to the through port of the optical waveguide 664 on the output side exhibits an inverted characteristic relative to the intensity of the current flowing through the photodiode 65b connected to the drop port of the optical waveguide 665 on the other output side.

[0129] That is, the intensity of the current flowing through the photodiode 65a and the photodiode 65b with respect to the phase is reversed from 1 to 0 and from 0 to 1 every 2π. When the intensity of the current flowing through the photodiode 65a with respect to the phase is 1, the intensity of the current flowing through the photodiode 65b with respect to the phase is 0. Conversely, when the intensity of the current flowing through the photodiode 65a with respect to the phase is 0, the intensity of the current flowing through the photodiode 65b with respect to the phase is 1.

[0130] In short, the slope of the intensity of the current flowing through the photodiode 65 a also obtains the same slope as the slope of the intensity of the current flowing through the photodiode 65 b .

[0131] Therefore, as the second light receiver 65 , either the photodiode 65 a or the photodiode 65 b may be used.

[0132] Regarding the output from the second light receiver 65, the laser light received by the optical coupler 61, i.e., coupled to the rear laser light Lb from the semiconductor laser 5 and then demultiplexed by the demultiplexer 62, is filtered by the ring resonator filter 64a serving as the phase variable filter 64 and converted into a current. In this example, the laser light resonating with the rear laser light Lb is converted into a current. Therefore, if the wavelength of the rear laser light Lb changes according to the wavelength dependence based on the ring resonator filter 64a, the current value from the second light receiver 65 also changes.

[0133] Therefore, the current value Iλ obtained from the second optical receiver 65 can be used as the wavelength monitor value Iλ used to obtain the wavelength monitor value Iλ / Ip of the semiconductor laser 5, and the ring resonator filter 64a and the second optical receiver 65 function as a wavelength monitor for the semiconductor laser 5.

[0134] The current value Iλ of the current obtained from the second optical receiver 65 is the wavelength monitor value Iλ, and the second optical receiver 65 outputs the optical power monitor value Ip as the second monitor value to the output terminal.

[0135] The wavelength monitor value Iλ, that is, the current value Iλ obtained from the second optical receiver 65, changes not only according to the wavelength of the backward laser light Lb of the semiconductor laser 5 but also according to the light intensity of the backward laser light Lb.

[0136] Therefore, by dividing the wavelength monitor value Iλ by the optical power monitor value Ip, it is possible to obtain the wavelength monitor value Iλ / Ip based only on the wavelength of the rear laser light Lb.

[0137] Since the semiconductor laser 5 and the light monitor 6 are regulated in temperature by the heat of the mounting surface 2 b of the temperature regulator 2 via the pedestal 3 , the temperature rise of the semiconductor laser 5 and the temperature rise of the light monitor 6 are the same.

[0138] If the temperature of the optical monitor 6 changes, the wavelength monitor value Iλ / Ip shows pure wavelength dependence.

[0139] In this example, by increasing the temperature in accordance with the wavelength of the laser light emitted by the semiconductor laser 5 , the wavelength monitor value Iλ / Ip exhibits a downwardly inclined slope.

[0140] By adjusting the temperature of the semiconductor laser 5 , the wavelength of the laser light from the semiconductor laser 5 can be adjusted, and the single wavelength of the laser light from the semiconductor laser 5 can be precisely controlled.

[0141] In this example, the optical filter 64 further includes a phase modulator 64b disposed on the optical waveguide forming a closed loop that constitutes the ring resonator filter 64a. The phase modulator 64b is the heater 7 in this example.

[0142] Generally, due to manufacturing errors of the ring resonator filter 64 a , there are individual differences in the position of the peak wavelength λfilt filtered by the ring resonator filter 64 a , that is, the peak position of the current value Iλ obtained from the second optical receiver 65 .

[0143] The phase modulator 64 b controls the ring resonator filter 64 a , that is, adjusts the position of the peak wavelength λfilt filtered by the ring resonator filter 64 a .

[0144] The current supplied to the heater 7 serving as the phase modulator 64 b is the target value Ih_target of the current supplied to the heater 7 so as to obtain the peak wavelength λfilt of the ring resonator filter 64 a when light output having a wavelength λLD of the target value λ_target and a light intensity of the target value Ip_target of the optical power monitoring value Ip can be obtained from the semiconductor laser 5, as obtained during preliminary preparation for operating the optical module.

[0145] That is, in order to obtain the current value Iλ that can be obtained from the second optical receiver 65 for obtaining the target value Iλ_target of the wavelength monitoring value Iλ / Ip relative to the target value λ_target of the wavelength λLD of the laser light from the semiconductor laser 5, the position of the peak wavelength λfilt filtered by the ring resonator filter 64a is adjusted by the phase modulator 64b.

[0146] For example, if the target value Iλ_target reaches the wavelength monitor value Iλ / Ip=0, even if the wavelength λLD of the laser light from the semiconductor laser 5 changes, the change in the wavelength monitor value Iλ / Ip is almost invisible, and the ring resonator filter 64a cannot be well controlled.

[0147] To avoid this, the temperature of the ring resonator filter 64a is adjusted by heating the ring resonator filter 64a with the heater 7 serving as the phase modulator 64b so that the target value Iλ_target becomes the wavelength monitoring value Iλ / Ip for control.

[0148] The target value Iλ_target for the control of the ring resonator filter 64a is determined by adjusting the temperature of the ring resonator filter 64a by the phase modulator 64b so as to be a wavelength monitor value Iλ / Ip near the central value in the region where the slope of the wavelength dependency is large with respect to the temperature of the optical monitor 6, in other words, where the temperature of the ring resonator filter 64a varies greatly.

[0149] In addition, the optical monitor 6 may not be a planar waveguide optical monitor based on a silicon photonic chip, but a planar waveguide optical monitor in which the optical coupler 61, the splitter 62, the first optical receiver 63, the filter 64, the second optical receiver 65 and the optical waveguides 661 to 665 are integrated on the plane of the indium phosphide (InP) substrate 6A which is a compound semiconductor.

[0150] Alternatively, the optical monitor 6 may be a planar waveguide optical monitor in which the optical coupler 61, the splitter 62, the first optical receiver 63, the optical filter 64, the second optical receiver 65, and the optical waveguides 661 to 665 are integrated on a plane of a substrate 6A made of a glass material.

[0151] The optical coupler 61 , the demultiplexer 62 , the first optical receiver 63 , the optical filter 64 , the second optical receiver 65 , and the optical waveguides 661 to 665 do not necessarily need to be integrated, and individual components may be modularized.

[0152] The first light receiver 63 and the second light receiver 65 may be InP light receivers.

[0153] Heater 7 serving as phase modulator 64 b is disposed on the upper surface of light monitor 6 via heat insulating layer 6B.

[0154] In this example, the heat insulating layer 6B is a silicon oxide (SiO 2 ) layer formed on the substrate 6A of the optical monitor 6 so as to cover the optical coupler 61 , the splitter 62 , the first optical receiver 63 , the optical filter 64 , the second optical receiver 65 and the optical waveguides 661 to 665 .

[0155] Furthermore, when the light monitor 6 has sufficient heat insulation, the amount of heat generated by the heater 7 is small, and the influence on the thermistor 8 is small, the heat insulation layer 6B may not be provided.

[0156] The heater 7 is arranged on the upper surface of the light monitor 6 , but may be arranged on the pedestal 3 , the mounting surface 2 b of the temperature regulator 2 , or the inner surface 11 a of the base 11 .

[0157] In summary, in this example, as long as the heater 7 is housed in the package 1 and heats the interior of the package 1 , the temperature of the ring resonator filter 64 a in the optical monitor 6 can be adjusted directly or indirectly with minimal effect on the thermistor 8 .

[0158] like Figure 6 As shown, the temperature regulator 2 , the semiconductor laser 5 , the light monitor 6 , and the heater 7 are controlled by a control unit 9 .

[0159] The control unit 9 is input with temperature information from the thermistor 8, i.e., detection information on the temperature of the semiconductor laser 5 and the temperature of the light monitor 6, when preparing to operate the optical module. When the optical module is in operation, the control unit 9 is input with detection information on the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 regularly, periodically, or randomly.

[0160] The control unit 9 controls the drive current flowing into the semiconductor laser 5 so that the optical power monitoring value Ip input to the semiconductor laser 5 from the first light receiver 63 of the optical monitor 6 converges to within the range of ±10% of the target value Ip_target of the optical power monitoring value as the current setting value.

[0161] The control unit 9 controls the current supplied to the temperature regulator 2 so that the optical power monitoring value Ip from the first optical receiver 63 of the optical monitor 6 falls within the current setting value range of ±10% of the target optical power monitoring value Ip_target.

[0162] If the optical power monitoring value Ip is greater than the current setting value, the control unit 9 will supply current to the temperature regulator 2 for heating the mounting surface 2b of the temperature regulator 2. If the optical power monitoring value Ip is less than the current setting value, the control unit 9 will supply current to the temperature regulator 2 for cooling the mounting surface 2b of the temperature regulator 2.

[0163] As a result, the temperature regulator 2 performs the following control: if the optical power monitoring value Ip represented by the current obtained by the first light receiver 63 is greater than the current setting value, the temperature regulator 2 increases the temperature assigned to the semiconductor laser 5 and the light monitor 6; if the optical power monitoring value Ip is less than the current setting value, the temperature regulator 2 decreases the temperature assigned to the semiconductor laser 5 and the light monitor 6.

[0164] In addition, the control unit 9 receives input of the optical power monitoring value Ip from the first optical receiver 63 of the optical monitor 6 and the wavelength monitoring value Iλ from the second optical receiver 65 of the optical monitor 6, calculates the wavelength monitoring value Iλ / Ip based on the input optical power monitoring value Ip and the wavelength monitoring value Iλ, and controls the current supplied to the temperature regulator 2 in such a manner that the wavelength monitoring value Iλ / Ip converges within the range of the wavelength setting value of ±10% of the target value Iλ_target of the wavelength monitoring value Iλ / Ip when the wavelength λLD of the laser light of the semiconductor laser 5 becomes the target value λ_target.

[0165] When the wavelength monitor value Iλ / Ip deviates from the wavelength setting value, the control unit 9 supplies a current for changing the temperature of the mounting surface 2 b to the temperature regulator 2 .

[0166] In this example, if the wavelength monitoring value Iλ / Ip is greater than the wavelength setting value, the control unit 9 will supply an electric current for heating the mounting surface 2b of the temperature regulator 2 to the temperature regulator 2. If the wavelength monitoring value Iλ / Ip is less than the wavelength setting value, the control unit 9 will supply an electric current for cooling the mounting surface 2b of the temperature regulator 2 to the temperature regulator 2.

[0167] As a result, the temperature regulator 2 performs the following control, that is, if the wavelength monitoring value Iλ / Ip based on the optical power monitoring value Ip represented by the current obtained by the first optical receiver 63 and the wavelength monitoring value Iλ represented by the current obtained by the second optical receiver 65 is greater than the wavelength setting value, the temperature regulator 2 increases the temperature assigned to the semiconductor laser 5 and the optical monitor 6; if the wavelength monitoring value Iλ / Ip is less than the wavelength setting value, the temperature regulator 2 decreases the temperature assigned to the semiconductor laser 5 and the optical monitor 6.

[0168] In addition, the temperature regulator 2 performs the following control, that is, if the temperature applied to the semiconductor laser 5 and the optical monitor 6 increases due to the wavelength monitoring value Iλ / Ip being greater than the wavelength setting value, thereby causing the optical power monitoring value Ip to become less than the current setting value, the drive current supplied to the semiconductor laser 5 is increased; if the temperature applied to the semiconductor laser 5 and the optical monitor 6 decreases due to the wavelength monitoring value Iλ / Ip being less than the wavelength setting value, thereby causing the optical power monitoring value Ip to become greater than the current setting value, the drive current supplied to the semiconductor laser 5 is reduced.

[0169] The control unit 9 supplies a current of the target value Ih_target to the heater 7 serving as the phase modulator 64b for the filter 64 so as to obtain a light output of laser light having the target value λLD and the target value λ_target at the light intensity of the laser light of the semiconductor laser 5 .

[0170] As a result, the heater 7 heats the light monitor 6 , specifically, the ring resonator filter 64 a , under the control of the control unit 9 , thereby adjusting the temperature of the ring resonator filter 64 a .

[0171] The control unit 9 and the optical monitor 6 constitute a wavelength locker for controlling the wavelength of the laser light from the semiconductor laser 5 .

[0172] The optical module and the control unit 9 constitute an optical module device.

[0173] Since semiconductor laser 5, light monitor 6, temperature regulator 2, heater 7 and thermistor 8 exchange signals with control unit 9, they are electrically connected to pins P1 to P6 via wires (not shown) such as gold wires by wire bonding.

[0174] Pins P1-P6 pass through through-holes formed at designated locations on base 11 and are secured to base 11 by cured sealing glass that fills the gaps between the pins P1-P6 and the through-holes. The sealing glass electrically insulates the pins P1-P6 from base 11 and maintains airtightness.

[0175] One end surface of the ground pin P7 contacts the outer plane 11 b of the base 11 and is joined thereto by welding or soldering, whereby the ground pin P7 is fixed to the base 11 .

[0176] The ground pin P7 is electrically grounded, and the base 11 is set to the ground potential via the ground pin P7. That is, the base 11 also functions as a ground node.

[0177] The optical module according to the first embodiment can have a total of seven pins, namely, six pins P1 to P6 for each component and one ground pin P7 , and thus the optical module can be configured with a relatively small number of pins.

[0178] As a result, a standard CAN package with a maximum number of pins of 7 and a diameter of 5.6 mm can be used, thereby achieving miniaturization.

[0179] The inner lead portions of the pins P1 to P6 exposed from the inner plane 11a of the base 11 are connected as follows, for example. However, the relationship between the pins P1 to P6 and the components is shown as an example and is not limited to this example.

[0180] The pin P1 is connected to one electrode of the semiconductor laser 5 and transmits a drive current from the control unit 9 to the semiconductor laser 5. The pin P1 is a laser pin for the semiconductor laser 5.

[0181] Pins P2 and P3 are connected to a pair of electrodes, ie, a positive electrode and a negative electrode, of the temperature regulator 2, respectively, and transmit current supplied from the control unit 9 to the temperature regulator 2. Pins P2 and P3 are temperature regulator pins for the temperature regulator 2.

[0182] Pin P4 and pin P5 are connected to the output terminal of the light monitor 6, respectively, and transmit the monitoring value from the light monitor 6 to the control unit 9. Pin P4 and pin P5 are monitoring pins for the light monitor 6.

[0183] The pin P4 is connected to the output terminal of the first light receiver 63 of the light monitor 6 , and transmits the current representing the optical power monitor value Ip from the first light receiver 63 to the control unit 9 .

[0184] The pin P5 is connected to the output terminal of the second optical receiver 65 of the light monitor 6 , and transmits the current representing the wavelength monitor value Iλ from the second optical receiver 65 to the control unit 9 .

[0185] The pin P6 is a common pin for the heater and the thermistor, connected to one end of the heater 7 and one end of the thermistor 8 .

[0186] The other ends of the heater 7 and the thermistor 8 are electrically connected to the inner plane 11a of the base 11 at a ground potential (ground node) via wires (not shown) such as gold wires by wire bonding, and are connected to a ground pin P7.

[0187] That is, Figure 7 As shown, the heater 7 and the thermistor 8 are connected in parallel between a heater and thermistor common pin P6 and a ground pin P7.

[0188] Regarding the two components of the thermistor 8 and the heater 7 , the pin P6 can be shared by one heater and the thermistor, except for the ground pin P7 , thereby reducing the number of pins by one.

[0189] Next, a description will be given of a relationship between the thermistor 8 and the heater 7 , which are one feature of the optical module according to the first embodiment, and a pin related thereto, that is, a heater and thermistor common pin P6 .

[0190] As described above, the heater 7 functions as the phase modulator 64 b for the ring resonator filter 64 a in the optical filter 64 , and heats the ring resonator filter 64 a to adjust the temperature of the ring resonator filter 64 a.

[0191] Heater 7 is low power, resistance value R h high.

[0192] As described above, the thermistor 8 measures the internal temperature of the package 1 , and in particular measures and detects the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 , in order to accurately perform temperature control by the temperature regulator 2 .

[0193] Therefore, it is necessary to independently control the heater 7 and the thermistor 8 and to minimize the influence of heating by the heater 7 on the thermistor 8 . This point will be described.

[0194] The optical module according to the first embodiment has a heater 7 and a thermistor 8 electrically connected in parallel between a heater and thermistor common pin P6 and a ground pin P7 (ground node). The heater 7 and thermistor 8 shown below are used as reference examples.

[0195] The heater 7 in this example has the characteristics of a resistor, as in Figure 9 As shown as a reference example in FIG, for the thermistor 8, the ground pin P7 is common, but the resistance value R when the pin connected to one end is different h like Figure 10 As shown, a constant value of 0.5 kΩ is shown in the temperature range from 0 to 100 degrees.

[0196] That is, in this example, the heater 7 has a resistance value R that is independent of temperature within the operating temperature range of the optical module. h The 0.5 kΩ heater is a low-power, high-resistance heater.

[0197] exist Figure 10 In the figure, the horizontal axis represents the operating temperature of the optical module, which in this example is a temperature corresponding to the temperature of the semiconductor laser 5 and the temperature of the optical monitor 6, and the vertical axis represents the resistance value R of the heater 7. h .

[0198] The thermistor 8 has a resistance value R in this example. TH The characteristic of resistance that changes with temperature, such as Figure 9 As shown as a reference example, the resistance value R when the heater 7 is connected to the pin at one end is different. TH like Figure 11 As shown, as the temperature of the thermistor 8 rises, the resistance value decreases accordingly. At 0 degrees, the resistance value is 35 kΩ, at 25 degrees, the resistance value is 10 kΩ, at 50 degrees, the resistance value is 4.16 kΩ, and at 100 degrees, the resistance value is 0.7 kΩ.

[0199] exist Figure 11 In the figure, the horizontal axis represents the temperature of the semiconductor laser 5 and the temperature of the light monitor 6, and the vertical axis represents the resistance value R of the thermistor 8. TH .

[0200] In this example, the thermistor 8 used has the following characteristics: R0: 10 kΩ, T0: 25 degrees, and B constant: 3930K.

[0201] in addition, Figure 9The resistance value versus temperature curve of the thermistor 8 shown is for a thermistor having a resistance value R0 of 10 kΩ and a B constant of 3930 K at a temperature T0 of 25 degrees. The resistance value R0 of a well-known thermistor at a temperature T is used. TH The result obtained by the calculation method.

[0202] That is, in the operating temperature range of the optical module according to the first embodiment, the resistance value R of the thermistor 8 is TH The resistance value R of the heater 7 h The resistance value of thermistor 8 is R TH and the resistance value R of the heater 7 h Designed to be close to the value.

[0203] Specifically, the resistance value R of the heater 7 is h The resistance value R of the thermistor 8 is constant and does not depend on the temperature. TH The resistance value R of the thermistor 8 changes according to the temperature. TH The resistance value R of the heater 7 h The relationship is set such that, within the operating temperature range of the semiconductor laser 5 and the light monitor 6, the resistance value R of the thermistor 8 is TH Greater than the resistance value R of the heater 7 h , and is the resistance value R of the heater 7 h Less than 70 times.

[0204] The optical module involved in the first embodiment is formed by electrically connecting the heater 7 and the thermistor 8 in parallel between the common pin P6 for the heater and thermistor and the ground pin P7. A DC voltage is applied between the common pin P6 for the heater and thermistor and the ground pin P7 to allow a DC current to flow through the heater 7 and the thermistor 8. Since the thermistor 8 has a resistance value R in this example, TH The resistance value R can be read by measuring the voltage between the common pin P6 for the heater and thermistor and the ground pin P7. TH The temperature inside the package 1, that is, the temperature of the semiconductor laser 5 and the temperature of the light monitor 6, is measured and detected by the change in .

[0205] That is, Figure 8 As shown, the parallel resistance value R of the heater 7 and thermistor 8 between the heater and thermistor common pin P6 and the ground pin P7 is h / / R TH As the temperature of the thermistor 8 rises, the resistance value decreases accordingly. At 25 degrees, the resistance value R of the thermistor 8 is TH The resistance value of heater 7 is 10kΩ. h is 0.5kΩ, so the parallel resistance value Rh / / R TH The resistance value R of thermistor 8 is 0.48kΩ at 100 degrees. TH The resistance value of heater 7 is 0.7kΩ. h is 0.5kΩ, so the parallel resistance value R h / / R TH 0.29 kΩ is shown.

[0206] exist Figure 8 In the figure, the horizontal axis represents the temperature of the thermistor 8, that is, the temperature of the semiconductor laser 5 and the temperature of the light monitor 6, and the vertical axis represents the resistance value R of the heater 7. h and the resistance value R of thermistor 8 TH The parallel resistance value R h / / R TH .

[0207] Since the resistance value R of the heater 7 h The resistance value R of the thermistor 8 is constant regardless of temperature changes. TH It changes greatly with temperature, so Figure 8 It is clear that the parallel resistance value R of the heater 7 and the thermistor 8 is h / / R TH The parallel resistance value R is determined in a one-to-one relationship with the temperature of the thermistor 8, that is, the temperature of the semiconductor laser 5 and the temperature of the light monitor 6. h / / R TH The resistance value R of the thermistor 8 changes with the change in temperature, and can be read in accordance with the change in the temperature of the semiconductor laser 5 and the temperature of the light monitor 6. TH .

[0208] In order to read the resistance value R of thermistor 8 TH In this example, the resistance value R of the thermistor 8 is set to TH Greater than the resistance value R of the heater 7 h , the parallel resistance value R of the heater 7 and thermistor 8 h / / R TH Parallel resistance R relative to operating temperature range h / / R TH The maximum value changes by more than 0.1% for every 1 degree change in temperature.

[0209] That is, to satisfy the parallel resistance value R of the heater 7 and the thermistor 8 h / / R TH Parallel resistance R relative to operating temperature range h / / R THThe resistance value R of the thermistor 8 is set to TH and the resistance value R of the heater 7 h Designed to be close to the value.

[0210] As a result, the resistance value R of the thermistor 8 TH The measurement accuracy is improved.

[0211] Therefore, the parallel resistance value R between the heater and thermistor common pin P6 and the ground pin P7 is h / / R TH The control unit 9 allows a direct current to flow between the common pin P6 of the heater and thermistor and the ground pin P7. Based on the direct current flowing between the common pin P6 of the heater and thermistor and the ground pin P7, the control unit 9 measures the voltage between the common pin P6 of the heater and thermistor and the ground pin P7, thereby obtaining the temperature of the semiconductor laser 5 and the temperature of the light monitor 6.

[0212] Furthermore, the control unit 9 converts an analog voltage between the heater and thermistor common pin P6 and the ground pin P7 into a digital signal using an analog / digital converter (ADC) for control.

[0213] In addition, although a DC current also flows through the heater 7 when the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 are detected by the thermistor 8, since the heater 7 is a low-power heater used to adjust the temperature of the ring resonator filter 64a of the filter 64, the heater 7 does not have a negative impact on the temperature of the semiconductor laser 5 and the temperature of the light monitor 6.

[0214] During the preliminary preparation for the operation of the optical module, the thermistor 8 detects the temperature of the semiconductor laser 5 and the temperature of the optical monitor 6, and does not cause DC current to flow through the heater 7 for a long time. From this point of view, the heater 7 will not have a negative impact on the temperature of the semiconductor laser 5 and the temperature of the optical monitor 6.

[0215] In addition, although the thermistor 8 also detects the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 when the optical module is in operation, since this detection is performed regularly, periodically or randomly based on a short time, the heating of the heater 7 will not have a negative impact on the temperature of the semiconductor laser 5 and the temperature of the light monitor 6.

[0216] On the other hand, when the temperature of the ring resonator filter 64a is adjusted during operation of the optical module, if the control unit 9 supplies a DC current between the heater and thermistor common pin P6 and the ground pin P7, the resistance value Rh The resistance value R of thermistor 8 is set to TH Since the current Ih_target is small, more current flows through the heater 7 than the thermistor 8 , making it easy to supply the current of the target value Ih_target to the heater 7 , and making it easy to adjust the temperature of the ring resonator filter 64 a .

[0217] In summary, the optical module according to the first embodiment is formed by electrically connecting the heater 7 and the thermistor 8 in parallel between the heater and thermistor common pin P6 and the ground pin P7. However, the resistance value R of the heater 7 is h The resistance value R of thermistor 8 TH The resistance value R of the heater 7 is h Large enough to read the resistance value R of thermistor 8 TH The degree of change in the temperature of the ring resonator filter 64a during the operation of the optical module is adjusted so that the resistance value R of the heater 7 is reduced so that more current flows through the heater 7 than the thermistor 8. h Therefore, although the heater 7 and thermistor 8 share the heater and thermistor common pin P6 and the ground pin P7, a function equivalent to a structure in which different pins are connected to one end can be obtained.

[0218] In this example, as the heater 7, a resistor R having a resistance value R that is not temperature-dependent within the operating temperature range of the optical module is used. h However, as the heater 7, a heater having a resistance value R h A heater whose characteristics vary slightly depending on temperature.

[0219] In the case of a resistor with a value of R h In the case of a heater having characteristics that slightly depend on temperature, the parallel resistance value R read by the control unit 9 can be controlled by the control unit 9. h / / R TH , the control unit 9 corrects the resistance value R of the heater 7 h The temperature of the semiconductor laser 5 and the temperature of the light monitor 6 may be obtained by calculating the amount of temperature change.

[0220] Alternatively, you can also check the temperature and parallel resistance value R in advance. h / / R TH relationship, obtain Figure 8 The control unit 9 compares the temperature and the parallel resistance value R h / / R TH The relationship is stored as a table, and the parallel resistance value R read by the control unit 9 is h / / R THThe temperature of the semiconductor laser 5 and the temperature of the light monitor 6 are obtained by comparing with the relationship stored in the table.

[0221] As described above, the optical module according to the first embodiment includes: a temperature regulator 2 for regulating the temperature of the semiconductor laser 5; and a light monitor 6 for monitoring the light output and oscillation wavelength from the semiconductor laser 5. The optical module according to the first embodiment further includes a heater 7 and a thermistor 8. The heater 7 and the thermistor 8 are electrically connected in parallel. One end of the heater 7 and one end of the thermistor 8 are connected to a heater-thermistor common pin P6. Therefore, the heater 7 and the thermistor 8 are actually independently controlled. In addition to the ground pin P7, the pins for the heater 7 and the thermistor 8 can be a single heater-thermistor common pin P6, thereby achieving miniaturization of the optical module with advanced functions.

[0222] In summary, in the optical module involved in embodiment 1, for the heater 7 and the thermistor 8, the heating of the heater 7 and the temperature measurement and detection of the thermistor 8 can be independently performed through a common pin P6 of the heater and the thermistor, thereby achieving miniaturization of the optical module and improving the function of the optical module.

[0223] In the first embodiment, the heater 7 is used to adjust the temperature of the ring resonator filter 64 a in the optical monitor 6 , but may also be used to adjust the temperature of other components or to adjust the temperature environment within the package.

[0224] In addition, in embodiment 1, the thermistor 8 is used to measure and detect the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 in advance preparation for the operation of the optical module and when the optical module is in operation, but it can also be used to measure and detect other components or to measure and detect the temperature environment inside the package.

[0225] Implementation Method 2

[0226] based on Figure 12 An optical module according to the second embodiment will be described.

[0227] The optical module involved in embodiment 2 differs from the optical module involved in embodiment 1 in that a capacitor 71 electrically connected in series with the heater 7 between the common pin P6 of the heater and thermistor and the ground node, and an inductor 81 electrically connected in series with the thermistor 8 between the common pin P6 of the heater and thermistor and the ground node are housed in the package 1, and other aspects are the same or identical.

[0228] In addition, Figure 12 In, and Figure 7The same reference numerals as those in the drawings indicate the same or corresponding parts.

[0229] The following description will focus on the differences from the optical module according to the first embodiment.

[0230] The capacitor 71 is electrically connected in series between the heater 7 and the heater and thermistor common pin P6 .

[0231] The inductor 81 is electrically connected in series between the thermistor 8 and the heater and thermistor common pin P6 .

[0232] A series connection of the heater 7 and the capacitor 71 and a series connection of the thermistor 8 and the inductor 81 are electrically connected in parallel between the heater and thermistor common pin P6 .

[0233] When the optical module is operating, if the control unit 9 supplies an AC current between the heater and thermistor common pin P6 and the ground pin P7 so that an AC current having a target value Ih_target flows to the heater 7, the temperature of the ring resonator filter 64a is adjusted to a temperature at which the peak wavelength λfilt of the ring resonator filter 64a can be obtained.

[0234] Since the AC current is supplied between the heater and thermistor common pin P6 and the ground pin P7 , current does not flow through the series body of the thermistor 8 and the inductor 81 .

[0235] In short, AC power can be applied only to the series connection of the heater 7 and the capacitor 71 .

[0236] On the other hand, in the preliminary preparation for operating the optical module in order to more accurately understand the relationship between the target value of the monitoring value of the laser light from the semiconductor laser 5 and the temperature of the semiconductor laser 5 and the temperature of the light monitor 6, if the control unit 9 supplies a DC current between the heater and thermistor common pin P6 and the ground pin P7, the control unit 9 measures the DC voltage based on the DC current flowing between the heater and thermistor common pin P6 and the ground pin P7, thereby obtaining the resistance value between the heater and thermistor common pin P6 and the ground pin P7, and the resistance value of the inductor 81 is taken into account. Figure 11 The temperature of the semiconductor laser 5 and the temperature of the optical monitor 6 can be obtained from the relationship of the characteristic diagram shown.

[0237] Since a direct current is supplied between the heater and thermistor common pin P6 and the ground pin P7 , current does not flow through the series body of the heater 7 and the capacitor 71 .

[0238] In addition, since the resistance value of the inductor 81 is almost negligible, the resistance value between the heater and thermistor common pin P6 and the ground pin P7 can be used as the resistance value R of the thermistor 8. TH get.

[0239] In short, the resistance value R of the thermistor 8 can be obtained by simply applying DC power to the series body of the thermistor 8 and the inductor 81. TH .

[0240] Even when the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 are detected regularly, periodically or randomly by the thermistor 8 during operation of the optical module, the control unit 9 supplies a DC current between the heater and thermistor common pin P6 and the ground pin P7.

[0241] By supplying a DC current between the common pin P6 for the heater and thermistor and the ground pin P7, the resistance value R of the thermistor 8 can be obtained without flowing a current through the series body of the heater 7 and the capacitor 71. TH .

[0242] As described above, the optical module according to the second embodiment has the effect of enabling miniaturization of the optical module with advanced functions, similar to the optical module according to the first embodiment.

[0243] Furthermore, in the optical module according to the second embodiment, when the heater 7 is heating, current does not flow through the thermistor 8, and AC power can be applied only to the series body of the heater 7 and the capacitor 71. When the temperature is measured or detected by the thermistor 8, current does not flow through the heater 7, and DC power can be applied only to the series body of the thermistor 8 and the inductor 81, thereby obtaining the resistance value R of the thermistor 8. TH .

[0244] In addition, if Figure 13 As shown, the optical module involved in embodiment 1 can also be configured with: an inductor 72 electrically connected in series with the heater 7 between the common pin P6 of the heater and thermistor and the ground node, and a capacitor 82 electrically connected in series with the thermistor 8 between the common pin P6 of the heater and thermistor and the ground node.

[0245] exist Figure 13In the variation of the optical module involved in the second embodiment shown, when the optical module is in operation, if the control unit 9 supplies a DC current between the common pin P6 for the heater and thermistor and the ground pin P7 in such a manner that an AC current having a current of a target value Ih_target flows to the heater 7, then DC power can be applied only to the series body of the heater 7 and the inductor 72, and the temperature of the ring resonator filter 64a can be adjusted without causing current to flow through the series body of the thermistor 8 and the capacitor 82.

[0246] On the other hand, when the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 are detected by the thermistor 8, if the control unit 9 supplies an AC current between the common pin P6 for the heater and thermistor and the ground pin P7, the AC power can be applied only to the series connection of the thermistor 8 and the capacitor 82, and the resistance value R of the thermistor 8 can be obtained without flowing the AC current through the series connection of the heater 7 and the inductor 72. TH , the temperature of the semiconductor laser 5 and the temperature of the light monitor 6 can be detected and measured.

[0247] exist Figure 13 The modified example of the optical module according to the second embodiment shown also has the same effects as those of the optical module according to the second embodiment.

[0248] Furthermore, the various embodiments may be freely combined, arbitrary components of the various embodiments may be modified, or arbitrary components of the various embodiments may be omitted.

[0249] Industrial applicability

[0250] The optical module according to the present disclosure is suitable for use in a large-capacity optical communication system, and is particularly suitable for use in a digital coherent communication system.

[0251] Furthermore, the optical module according to the present disclosure is suitable for a TO-CAN type optical transmission module for optical communication including a single wavelength semiconductor laser.

[0252] Description of reference numerals:

[0253] 1…package; 11…base; 12…cover; 13…window; 2…temperature regulator; 3…pedestal; 4…submount for semiconductor laser; 5…semiconductor laser; 6…light monitor; 61…optical coupler; 62…wave splitter; 63…first photoreceiver; 64…optical filter; 65…second photoreceiver; 7…heater; 71…capacitor; 72…inductor; 8…thermistor; 81…inductor; 82…capacitor; 9…control unit; P1 to P7…pins.

Claims

1. An optical module, wherein: have: The package body is composed of a base and a cylindrical window cover fixed with an opening end surface of the side wall portion in contact with and fixed to the peripheral end portion of the inner plane of the base; a semiconductor laser housed in the package and emitting laser light from the window with the window cover; a light monitor housed in the package, receiving the laser light from the semiconductor laser and monitoring the laser light from the semiconductor laser; a temperature regulator housed in the package, configured to control a change in the temperature applied to the semiconductor laser and the light monitor when a monitoring value from the light monitor deviates from a set monitoring value, thereby regulating the temperature of the semiconductor laser and the light monitor; a heater housed in the packaging body; a thermistor housed in the package and electrically connected in parallel with the heater; a laser lead penetrating the base while being electrically insulated from the base, and having an electrode of the semiconductor laser connected to an inner lead portion exposed from an inner plane of the base; a monitor pin, which penetrates the base in an electrically insulated manner and has an inner lead portion exposed from an inner plane of the base connected to an output terminal of the light monitor; a temperature regulator pin, which penetrates the base in an electrically insulated manner and has an electrode of the temperature regulator connected to an inner lead portion exposed from an inner plane of the base; A common lead for the heater and thermistor, which passes through the base in an electrically insulated manner and has one end of the heater and one end of the thermistor connected to an inner lead portion exposed from an inner plane of the base; and The grounding pin is electrically connected to the base.

2. The optical module according to claim 1, wherein: The temperature regulator is placed on the base. The optical module includes a base, which is mounted and fixed on the mounting surface of the temperature regulator and has a vertical portion on which the semiconductor laser is mounted and fixed, a flat portion formed integrally with the vertical portion and on which the light monitor is mounted and fixed at a position to receive rear laser light from the semiconductor laser, and a step portion formed on the opposite side of the vertical surface of the vertical portion and having a horizontal surface, i.e., a mounting surface, on which the thermistor is mounted and fixed.

3. The optical module according to claim 1, wherein: The light monitor has: a first light receiver for receiving laser light from the semiconductor laser; an optical filter receiving laser light from the semiconductor laser; and The second light receiver receives the laser light through the filter. The monitor pins include a pin connected to the output end of the first light receiver and a pin connected to the output end of the second light receiver.

4. The optical module according to claim 1, wherein: The temperature regulator is a thermoelectric cooler composed of a Peltier element having a positive electrode and a negative electrode. The temperature regulator pins include a pin connected to a positive electrode of the temperature regulator and a pin connected to a negative electrode of the temperature regulator.

5. The optical module according to any one of claims 1 to 4, wherein The thermistor has a characteristic of being a resistor whose resistance value changes according to temperature. The resistance value of the thermistor is greater than the resistance value of the heater within the operating temperature range of the semiconductor laser and the light monitor, and is 70 times or less of the resistance value of the heater.

6. The optical module according to any one of claims 1 to 4, wherein: The thermistor has a characteristic of being a resistor whose resistance value changes according to temperature. The resistance value of the heater is constant within the operating temperature range of the semiconductor laser and the light monitor. In the operating temperature range, the resistance value of the thermistor is greater than the resistance value of the heater, and the parallel resistance value of the thermistor and the heater changes by more than 0.1% per 1 degree temperature change relative to the maximum value of the parallel resistance value of the thermistor and the heater in the operating temperature range.

7. The optical module according to claim 1, wherein: The optical monitor is a planar waveguide type optical monitor having an optical coupler, a demultiplexer, a first optical receiver, an optical filter, and a second optical receiver. The monitoring value from the light monitor includes a first monitoring value and a second monitoring value. The first optical receiver receives the laser light from the semiconductor laser via the optical waveguide and then demultiplexed by the demultiplexer, and performs photoelectric conversion on the received light to output the first monitoring value to an output terminal. The second optical receiver receives the laser light from the semiconductor laser after being received by the optical coupler and then demultiplexed by the demultiplexer, and the other laser light filtered by the optical filter, and performs photoelectric conversion on the received light to output the second monitoring value to the output terminal. The monitor pins are composed of a pin connected to the output end of the first light receiver and a pin connected to the output end of the second light receiver. The heater adjusts the temperature of the light monitor by heating the light monitor.

8. The optical module according to claim 7, wherein: The thermistor has a characteristic of being a resistor whose resistance value changes according to temperature. The resistance value of the thermistor is greater than the resistance value of the heater within the operating temperature range of the semiconductor laser and the light monitor, and is 70 times or less of the resistance value of the heater.

9. The optical module according to claim 7, wherein: The thermistor has a characteristic of being a resistor whose resistance value changes according to temperature. The resistance value of the heater is constant within the operating temperature range of the semiconductor laser and the light monitor. In the operating temperature range, the resistance value of the thermistor is greater than the resistance value of the heater, and the parallel resistance value of the thermistor and the heater changes by more than 0.1% per 1 degree temperature change relative to the maximum value of the parallel resistance value of the thermistor and the heater in the operating temperature range.

10. The optical module according to any one of claims 1 to 4 and 7 to 9, wherein: The optical module has: a capacitor electrically connected in series with the heater between a common pin of the heater and thermistor and a ground node; and An inductor is electrically connected in series with the thermistor between the common pin of the heater and thermistor and the ground node.

11. The optical module according to any one of claims 1 to 4 and 7 to 9, wherein: The optical module has: an inductor electrically connected in series with the heater between a common pin of the heater and thermistor and a ground node; and A capacitor is electrically connected in series with the thermistor between the common pin of the heater and thermistor and the ground node.

12. The optical module according to any one of claims 1 to 4 and 7 to 9, wherein: The base is a metal disc with a diameter of 5.6 mm. The cover with window is in a cylindrical shape.

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