Optical module

Abstract

The optical module includes a semiconductor laser (15) having an optical output coupler (15d) that emits backward laser light (Lb) in association with the emission of forward laser light (Lf) from the front end portion, and an optical monitor (16) having an optical coupling coupler (16c) that receives and couples the backward laser light (Lb) emitted from the optical output coupler (15d). The semiconductor laser (15) and the optical monitor (16) are overlapped such that the optical output coupler (15d) and the optical coupling coupler (16c) face each other.

Description

Technical Field

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

Background Art

[0002] As one of the methods for increasing the capacity of an optical communication system, there is a digital coherent communication method. This digital coherent communication method is a method of transmitting a large number of channels by loading signals not only on the intensity of light but also on the phase. In order to extract the phase information of light, since the interference phenomenon of light is used, the light source of the transmitter that sends the signal and the local light that becomes the interfering light at the receiver that receives the signal both need to have their wavelengths precisely controlled.

[0003] What is used as the above light source is a single-mode laser. A single-mode laser oscillates at a single wavelength, but the oscillation wavelength and the optical output intensity may change due to manufacturing errors and environmental temperature. For this reason, a wavelength locker for wavelength control and an optical intensity monitor are essential in a light source module for digital coherent communication equipped with a single-mode laser. In particular, precise control of 0.1 nm or less is required for the oscillation wavelength. Therefore, Patent Document 1 discloses an optical module that controls the oscillation wavelength of a laser with high precision.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The optical module disclosed in Patent Document 1 includes a laser and an etalon. The transmittance of the etalon changes according to the wavelength of the transmitted light. Therefore, in the optical module disclosed in Patent Document 1, the backward laser light of the laser can be transmitted through the etalon, and the intensity of the backward laser light can be monitored using a light receiving element. As a result, the optical module disclosed in Patent Document 1 can detect changes in the oscillation wavelength of the laser.

[0006] However, since the optical module disclosed in Patent Document 1 is provided with temperature control elements for both the laser and the etalon, it causes an increase in the size of the module. In addition, the optical module disclosed in Patent Document 1 requires a plurality of components to collimate the light incident on the etalon. Therefore, the manufacturing cost of the optical module disclosed in Patent Document 1 may increase.

[0007] On the other hand, the optical module disclosed in Patent Document 2 is provided with a planar waveguide type optical monitor for the purpose of reducing the number of components and achieving miniaturization. At this time, in the pedestal provided in the optical module, the mounting surface of the laser and the mounting surface of the optical monitor are different surfaces from each other. Therefore, in order to efficiently couple the backward laser light emitted from the laser output unit to the optical monitor, it is necessary to mount the laser and the optical monitor with high precision on each mounting surface.

[0008] The present disclosure has been made to solve the above problems, and an object thereof is to provide an optical module capable of efficiently coupling the backward laser light emitted from the laser output unit to the optical monitor without providing a mounting surface dedicated to the optical monitor on the pedestal.

Means for Solving the Problems

[0009] The optical module according to the present disclosure includes a laser output unit having an optical output coupler that emits backward laser light in association with the emission of forward laser light from the front end, and an optical monitor having an optical coupling coupler that receives and couples the backward laser light emitted from the optical output coupler. The laser output unit and the optical monitor are overlapped such that the optical output coupler and the optical coupling coupler face each other.

Effect of the Invention

[0010] According to the present disclosure, the backward laser light emitted from the laser output unit can be efficiently coupled to the optical monitor without providing a dedicated mounting surface for the optical monitor on the pedestal.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0012] Hereinafter, in order to explain the present disclosure in more detail, embodiments for carrying out the present disclosure will be described with reference to the accompanying drawings.

[0013] Embodiment 1. The optical module according to Embodiment 1 will be described with reference to FIGS. 1 to 5.

[0014] FIG. 1 is a longitudinal sectional view of a state in which the cap 18 in the optical module according to Embodiment 1 is removed. FIG. 2 is a perspective view of the optical module according to Embodiment 1.

[0015] The optical module according to Embodiment 1 is, for example, an optical module for digital coherent communication. As shown in FIGS. 1 and 2, the optical module according to Embodiment 1 includes a stem 11, a temperature regulator 12, a pedestal 13, a submount for a semiconductor laser (hereinafter referred to as a submount) 14, a semiconductor laser 15, a planar waveguide type optical monitor (hereinafter referred to as an optical monitor) 16, a thermistor 17, a cap 18, a window member 19, and a plurality of pins 20. Note that the semiconductor laser 15 constitutes a laser output unit.

[0016] The stem 11 is formed in a disk shape. This stem 11 is formed of a conductive material such as a metal material, for example. The stem 11 also has a main surface 11a. This main surface 11a is a flat vertical surface and constitutes a mounting surface for the temperature regulator 12. Note that the outer shape of the stem 11 may be an ellipse, a triangle, a rectangle, or the like.

[0017] The temperature regulator 12 is fixed to the stem 11. The temperature regulator 12 has a left side surface 12a and a right side surface 12b. The left side surface 12a and the right side surface 12b are arranged parallel to the main surface 11a. Among these, the right side surface 12b is mounted on the main surface 11a.

[0018] The temperature regulator 12 controls the temperatures of the semiconductor laser 15 and the optical monitor 16 via the pedestal 13. Specifically, when a control current is supplied, the temperature regulator 12 heats or cools the semiconductor laser 15 and the optical monitor 16 according to the direction of the control current. At this time, when the stem 11 receives the heat emitted from the temperature regulator 12, it discharges the heat to the outside. The temperature regulator 12 is, for example, a thermoelectric cooler (TEC) composed of a Peltier element or the like.

[0019] The pedestal 13 is mounted on the left side surface 12a of the temperature regulator 12. This pedestal 13 has an L shape when viewed from the side of the optical module. For this reason, the pedestal 13 has a mounting surface 13a that is a horizontal plane and a vertical surface 13b. The mounting surface 13a and the vertical surface 13b are arranged perpendicular to each other. The pedestal 13 transmits the heat emitted from the temperature regulator 12 to the semiconductor laser 15 and the optical monitor 16. The pedestal 13 is formed of, for example, a metal material having excellent thermal conductivity.

[0020] The submount 14 is mounted on the mounting surface 13a of the pedestal 13. This submount 14 is composed of, for example, a substrate made of aluminum nitride dielectric with a metal wiring layer pattern formed on the surface.

[0021] The semiconductor laser 15 is mounted on the mounting surface 13a of the pedestal 13 via the submount 14. Further, the optical monitor 16 is mounted on the semiconductor laser 15. Details of the mounting of the optical monitor 16 on the semiconductor laser 15 will be described later.

[0022] Therefore, the pedestal 13 conducts the heat generated from the temperature controller 12 and adjusts the temperatures of the semiconductor laser 15 and the optical monitor 16 through the submount 14. At this time, the semiconductor laser 15 and the optical monitor 16 whose temperatures are adjusted by the temperature controller 12 are arranged so as to overlap with respect to one mounting surface 13a. For this reason, the optical module according to Embodiment 1 can reduce the occupied area on the mounting surface 13a by the semiconductor laser 15 and the optical monitor 16. As a result, the optical module according to Embodiment 1 can reduce the size and weight of the pedestal 13.

[0023] The semiconductor laser 15 is a single-wavelength semiconductor laser, that is, a single-mode laser that oscillates at a single wavelength. The semiconductor laser 15 emits forward laser light Lf from the front end face (emission face) and backward laser light Lb from the upper face. The forward laser light Lf is used for optical communication. The backward laser light Lb is monitored by being emitted toward the optical monitor 16. The optical axis of the forward laser light Lf and the optical axis of the backward laser light Lb are orthogonal to each other.

[0024] The thermistor 17 is provided on the pedestal 13. This thermistor 17 measures the temperature of the heat conducted from the temperature controller 12 to the semiconductor laser 15 and the optical monitor 16.

[0025] The cap 18 is formed in a cylindrical shape with a lid. The open end of the cap 18 is fixed to the main face 11a of the stem 11. The cap 18 is provided so as to cover the temperature controller 12, the pedestal 13, the submount 14, the semiconductor laser 15, the optical monitor 16, and the thermistor 17 from the outside. The cap 18 is formed of, for example, a metal material or a resin material.

[0026] The window member 19 is fitted into the lid portion of the cap 18. This window member 19 condenses and passes the forward laser light Lf emitted from the semiconductor laser 15. The window member 19 is, for example, a planar glass or a lens.

[0027] The plurality of pins 20 are electrically connected to the temperature controller 12, the semiconductor laser 15, and the optical monitor 16. Each pin 20 is supported in a penetrating manner with respect to the stem 11. At this time, each pin 20 is insulated from the stem 11.

[0028] The optical module according to the first embodiment includes a control unit (not shown). The temperature controller 12, the semiconductor laser 15, and the optical monitor 16 are controlled by the control unit. The control unit exchanges signals with each of the temperature controller 12, the semiconductor laser 15, and the optical monitor 16 through the corresponding pins 20. Further, the control unit controls the current and voltage to the temperature controller 12, the semiconductor laser 15, and the optical monitor 16 through the corresponding pins 20, and controls the light intensity and wavelength of the forward laser light Lf emitted from the semiconductor laser 15.

[0029] Next, the mounting of the optical monitor 16 on the semiconductor laser 15 will be described with reference to FIGS. 3 to 5. FIG. 3 is an enlarged view of the main part of FIG. 1. FIG. 4 is a plan view of a state before the semiconductor laser 15 and the optical monitor 16 are stacked on each other. FIG. 5 is a plan view of a state in which the semiconductor laser 15 and the optical monitor 16 are stacked on each other.

[0030] As shown in FIG. 3, the semiconductor laser 15 has an upper surface 15a and a lower surface 15b. The upper surface 15a and the lower surface 15b are surfaces located on opposite sides of each other in the thickness direction of the semiconductor laser 15. Further, the optical monitor 16 has an upper surface 16a and a lower surface 16b. The upper surface 16a and the lower surface 16b are surfaces located on opposite sides of each other in the thickness direction of the optical monitor 16.

[0031] The lower surface 15b of the semiconductor laser 15 is mounted on the upper surface of the submount 14. The lower surface 16b of the optical monitor 16 is mounted on the upper surface 15a of the semiconductor laser 15. That is, the lower surface 15b of the semiconductor laser 15 serves as the mounting surface for the upper surface of the submount 14. The lower surface 16b of the optical monitor 16 serves as the mounting surface for the upper surface 15a of the semiconductor laser 15.

[0032] As shown in FIG. 4, the semiconductor laser 15 has a laser stripe 15c, an optical output coupler 15d, a plurality of electrodes 15e, 15f, and a plurality of lead wires 15g. The laser stripe 15c, the optical output coupler 15d, the plurality of electrodes 15e, 15f, and the plurality of lead wires 15g are provided on the upper surface 15a which is the same plane.

[0033] The laser stripe 15c emits forward laser light Lf. The optical output coupler 15d emits backward laser light Lb. The optical output coupler 15d is connected to the rear end of the elongated laser stripe 15c. Thus, by having the optical output coupler 15d, the semiconductor laser 15 can output the backward laser light Lb from the upper surface 15a. The optical output coupler 15d is, for example, a grating coupler.

[0034] The electrodes 15e, 15f are arranged around the laser stripe 15c and the optical output coupler 15d. Note that the electrodes 15e, 15f constitute the laser-side electrodes. Further, the electrode 15e constitutes the laser-side electrode for wire bonding, and the electrode 15f constitutes the laser-side electrode for connection.

[0035] Although details will be described later, when the optical monitor 16 is mounted on the semiconductor laser 15, the electrode 15e is arranged in a range not covered by the optical monitor 16. Further, when the optical monitor 16 is mounted on the semiconductor laser 15, the electrode 15f is covered by the optical monitor 16 and is electrically connected to the electrode 16i thereof.

[0036] The routing wire 15g electrically connects between the electrodes 15e and 15f respectively. Although details will be described later, the electrode 15f to which the routing wire 15g is connected corresponds to the electrode 16i among the electrodes 16i of the optical monitor 16 that is electrically connected to the first photoreceiver 16g and the second photoreceiver 16h.

[0037] As shown in FIG. 4, the optical monitor 16 includes an optical coupling coupler 16c, an optical demultiplexer 16d, an optical filter 16e, a heater 16f, a first photoreceiver 16g, a second photoreceiver 16h, and a plurality of electrodes 16i. The optical coupling coupler 16c, the optical demultiplexer 16d, the optical filter 16e, the heater 16f, the first photoreceiver 16g, the second photoreceiver 16h, and the plurality of electrodes 16i are provided on the lower surface 16b that is the same plane. Between the optical coupling coupler 16c and the optical demultiplexer 16d, between the optical demultiplexer 16d and the optical filter 16e, between the optical filter 16e and the heater 16f, between the heater 16f and the first photoreceiver 16g, and between the optical demultiplexer 16d and the second photoreceiver 16h are respectively connected by optical waveguides (not shown).

[0038] The optical monitor 16 is, for example, a planar waveguide type optical monitor formed by integrating an optical coupling coupler 16c, an optical demultiplexer 16d, an optical filter 16e, a heater 16f, a first photoreceiver 16g, a second photoreceiver 16h, a plurality of electrodes 16i, and an optical waveguide on the surface of a silicon (Si) substrate.

[0039] The optical coupling coupler 16c couples the rear laser light Lb incident perpendicularly to the lower surface 16b of the optical monitor 16 and transmits it to the optical demultiplexer 16d. The optical coupling coupler 16c is, for example, a grating coupler.

[0040] The optical demultiplexer 16d receives the rear laser light Lb transmitted from the optical coupling coupler 16c and demultiplexes the received rear laser light Lb into two laser lights.

[0041] The first photoreceptor 16g receives one of the laser lights demultiplexed by the optical demultiplexer 16d, and photoelectrically converts the received one of the laser lights. Further, after photoelectrically converting one of the laser lights, the first photoreceptor 16g outputs a current corresponding to the light intensity of the one of the laser lights. Since the first photoreceptor 16g directly converts the light intensity of the rear laser light Lb coupled by the optical coupling coupler 16c into a current, it functions as an optical power monitor for the semiconductor laser 15. Furthermore, the first photoreceptor 16g is electrically connected to the corresponding electrode 16i. Therefore, the first photoreceptor 16g can output a current corresponding to the light intensity of one of the laser lights to the electrode 16i.

[0042] The optical filter 16e receives the other laser light demultiplexed by the optical demultiplexer 16d, and transmits the received other laser light to the second photoreceptor 16h via the optical filter 16e. The optical filter 16e has, for example, a temperature dependence of the wavelength of light. Therefore, the peak value of the wavelength of the laser light output from the optical filter 16e shifts toward the longer wavelength side as the temperature of the optical filter 16e increases. The optical filter 16e is, for example, a ring resonator with a phase shifter or a Mach-Zehnder interferometer with a phase shifter.

[0043] The second photoreceptor 16h converts the laser light (laser light resonated with the rear laser light Lb) filtered by the optical filter 16e into a current. At this time, when the wavelength of the rear laser light Lb changes, the current value output from the second photoreceptor 16h also changes. Further, the second photoreceptor 16h is electrically connected to the corresponding electrode 16i. Therefore, the second photoreceptor 16h can output a current corresponding to the light intensity of the other laser light to the electrode 16i.

[0044] The electrode 16i is disposed around the optical coupling coupler 16c, the optical demultiplexer 16d, the optical filter 16e, the heater 16f, the first photoreceptor 16g, and the second photoreceptor 16h. The electrode 16i corresponds to the electrode 15f. Note that the electrode 16i constitutes a monitor-side electrode and a connection-use monitor-side electrode.

[0045] Therefore, when the optical monitor 16 is mounted on the semiconductor laser 15, as shown in FIG. 4, first, the semiconductor laser 15 has its upper surface 15a facing upward, and the optical monitor 16 has its lower surface 16b facing upward. Next, as shown in FIGS. 4 and 5, from such a state, the optical monitor 16 is turned over so that its upper surface 16a and lower surface 16b are in a vertically reversed state, and thus the lower surface 16b is mounted on the upper surface 15a of the semiconductor laser 15.

[0046] At this time, the light-emitting coupler 15d and the light-combining coupler 16c face each other. Therefore, the light-combining coupler 16c can receive and combine the rear laser light Lb emitted from the light-emitting coupler 15d. Also, the electrode 15f and the electrode 16i face each other respectively. The electrode 15f and the electrode 16i are joined to each other using gold bumps or solder bumps or the like. Therefore, the optical module according to Embodiment 1 can electrically connect the semiconductor laser 15 and the optical monitor 16.

[0047] And since the optical monitor 16 is mounted after being turned over, wire bonding cannot be performed on the electrode 16i that is electrically connected to the first photoreceiver 16g and the second photoreceiver 16h. That is, a current corresponding to the light intensity of the laser light cannot be extracted from the electrode 16i that is electrically connected to the first photoreceiver 16g and the second photoreceiver 16h.

[0048] However, in the optical module according to Embodiment 1, the lead wire 15g connects the electrode 15f that is electrically connected to the electrode 16i and the electrode 15e that is not covered by the optical monitor 16. Therefore, the optical module according to Embodiment 1 can bond the wire 30 to the electrode 15e that is not covered by the optical monitor 16, and extract a current corresponding to the light intensity of the laser light from the electrode 15e.

[0049] Therefore, the optical module according to Embodiment 1 can detect the optical output and oscillation wavelength of the semiconductor laser 15 by measuring the current values output from the first light receiver 16g and the current values output from the second light receiver 16h.

[0050] Here, in the optical module disclosed in Patent Document 2, it is necessary to keep the distance between a semiconductor laser and an optical monitor mounted on mounting surfaces with different installation positions from contacting each other during mounting to about several hundred μm. Such mounting hinders the improvement of the optical coupling efficiency in the optical monitor. Further, in the optical module disclosed in Patent Document 2, variations in the respective thicknesses of the submount and the semiconductor laser, or variations in the emission direction of the backward laser light from the semiconductor laser due to cleavage errors may occur. In this case, in the optical module disclosed in Patent Document 2, it becomes difficult to efficiently and stably couple the backward laser light to the optical monitor.

[0051] On the other hand, in the optical module according to Embodiment 1, the upper surface 15a of the semiconductor laser 15 and the lower surface 16b of the optical monitor 16 are connected so as to face each other and overlap. For this reason, in the optical module according to Embodiment 1, the semiconductor laser 15 and the optical monitor 16 can be brought closer to each other, for example, to about several tens of μm, without worrying about mutual contact. As a result, the optical module according to Embodiment 1 can improve the optical coupling efficiency in the optical monitor 16 without providing the mounting surface of the optical monitor 16 on the pedestal 13.

[0052] As described above, the optical module according to Embodiment 1 includes a semiconductor laser 15 having an optical output coupler 15d that emits a rear laser beam Lb in accordance with the emission of a front laser beam Lf from the front end portion, and an optical monitor 16 having an optical coupling coupler 16c that receives and couples the rear laser beam Lb emitted from the optical output coupler 15d. The semiconductor laser 15 and the optical monitor 16 are overlapped such that the optical output coupler 15d and the optical coupling coupler 16c face each other. Therefore, the optical module according to Embodiment 1 can efficiently couple the rear laser beam Lb emitted from the semiconductor laser 15 to the optical monitor 16 without providing a mounting surface dedicated to the optical monitor on the pedestal 13.

[0053] In addition, since the optical module according to Embodiment 1 connects the semiconductor laser 15 and the optical monitor 16 so as to face each other and overlap, the size and weight of the pedestal 13 can be reduced.

[0054] Embodiment 2. The optical module according to Embodiment 2 will be described with reference to FIGS. 6 and 7.

[0055] FIG. 6 is a plan view of a state before the optical amplifier 25 and the reflective filter integrated optical monitor (hereinafter referred to as the optical monitor) 26 are stacked on each other in the optical module according to Embodiment 2. FIG. 7 is a plan view of a state in which the optical amplifier 25 and the optical monitor 26 are stacked on each other in the optical module according to Embodiment 2. Note that components having the same functions as those described in Embodiment 1 described above are denoted by the same reference numerals, and their descriptions are omitted.

[0056] The optical module according to Embodiment 2 includes an optical amplifier 25 and an optical monitor 26 instead of the semiconductor laser 15 and the optical monitor 16 of the optical module according to Embodiment 1. Note that the optical amplifier 25 constitutes a laser output section.

[0057] As shown in FIG. 6, the optical amplifier 25 has an upper surface 25a and a lower surface 25b. The upper surface 25a and the lower surface 25b are surfaces that are located on opposite sides of each other in the thickness direction of the optical amplifier 25. Further, the optical monitor 26 has an upper surface 26a and a lower surface 26b. The upper surface 26a and the lower surface 26b are surfaces that are located on opposite sides of each other in the thickness direction of the optical monitor 26.

[0058] The lower surface 25b of the optical amplifier 25 is mounted on the upper surface of the submount 14. The lower surface 26b of the optical monitor 26 is mounted on the upper surface 25a of the optical amplifier 25. That is, the lower surface 25b of the optical amplifier 25 serves as a mounting surface for the upper surface of the submount 14. The lower surface 26b of the optical monitor 26 serves as a mounting surface for the upper surface 25a of the optical amplifier 25.

[0059] Also, as shown in FIG. 6, the optical amplifier 25 has an amplification stripe 25c, an optical output coupler 25d, a plurality of electrodes 25e, 25f, and a plurality of routing lines 25g. The amplification stripe 25c, the optical output coupler 25d, the plurality of electrodes 25e, 25f, and the plurality of routing lines 25g are provided on the upper surface 25a that is the same surface.

[0060] The amplification stripe 25c emits forward laser light Lf. The optical output coupler 25d emits backward laser light Lb. The optical output coupler 25d is connected to the rear end of the elongated amplification stripe 25c. In this way, by having the optical output coupler 25d, the optical amplifier 25 can output the backward laser light Lb from the upper surface 25a. The optical output coupler 25d is, for example, a grating coupler.

[0061] The electrodes 25e, 25f are disposed around the amplification stripe 25c and the optical output coupler 25d. Note that the electrodes 25e, 25f constitute laser-side electrodes. Further, the electrode 25e constitutes a laser-side electrode for wire bonding, and the electrode 25f constitutes a laser-side electrode for connection.

[0062] Although details will be described later, when the optical monitor 26 is mounted on the optical amplifier 25, the electrode 25e is disposed in a range not covered by the optical monitor 26. Further, when the optical monitor 26 is mounted on the optical amplifier 25, the electrode 25f is covered by the optical monitor 26 and is electrically connected to the electrode 26n thereof.

[0063] The jumper wire 25g electrically connects between the electrode 25e and the electrode 25f. Although details will be described later, the electrode 25f to which the jumper wire 25g is connected corresponds to the electrode 26n that is electrically connected to the first photoreceiver 26k and the second photoreceiver 26l among the electrodes 16n of the optical monitor 26.

[0064] As shown in FIG. 6, the optical monitor 26 includes an optical coupling coupler 26c, an optical demultiplexer 26d, a first optical filter 26e, a second optical filter 26f, a third optical filter 26g, a first heater 26h, a second heater 26i, a third heater 26j, a first photoreceiver 26k, a second photoreceiver 26l, a waveguide mirror 26m, and a plurality of electrodes 26n. The optical coupling coupler 26c, the optical demultiplexer 26d, the optical filters 26e to 26g, the heaters 26h to 26j, the first photoreceiver 26k, the second photoreceiver 26l, the waveguide mirror 26m, and the plurality of electrodes 26n are provided on the lower surface 26b which is the same plane. Further, they are connected to each other by an optical waveguide (not shown).

[0065] Note that the optical filters 26e to 26g have the same configuration and the same function. Further, the heaters 26h to 26j have the same configuration and the same function.

[0066] The optical monitor 26 is, for example, a reflective filter integrated optical monitor formed by integrating an optical coupling coupler 26c, an optical demultiplexer 26d, optical filters 26e to 26g, heaters 26h to 26j, a first photoreceiver 26k, a second photoreceiver 26l, a waveguide mirror 26m, a plurality of electrodes 26n, and an optical waveguide on the surface of a silicon (Si) substrate.

[0067] The optical coupling coupler 26c couples the rear laser beam Lb that has been incident perpendicularly to the lower surface 26b of the optical monitor 26, and transmits it to the waveguide mirror 26m via the optical filters 26f, 26g and the heaters 26i, 26j. The optical coupling coupler 26c is, for example, a grating coupler.

[0068] The waveguide mirror 26m allows a part of the rear laser beam Lb transmitted from the optical coupling coupler 26c to pass through.

[0069] The optical demultiplexer 26d receives a part of the rear laser beam Lb transmitted from the waveguide mirror 26m, and demultiplexes this received part of the rear laser beam Lb into two laser beams.

[0070] The first photoreceiver 26k receives one of the laser beams demultiplexed from the optical demultiplexer 26d, and photoelectrically converts this received one of the laser beams. Further, after photoelectrically converting one of the laser beams, the first photoreceiver 26k outputs a current corresponding to the optical intensity of that one of the laser beams. The first photoreceiver 26k functions as an optical power monitor for the optical amplifier 25 because it directly converts the optical intensity of the rear laser beam Lb coupled by the optical coupling coupler 26c into an electric current. Furthermore, the first photoreceiver 26k is electrically connected to the corresponding electrode 26n. For this reason, the first photoreceiver 26k can output a current corresponding to the optical intensity of one of the laser beams to the electrode 26n.

[0071] The first optical filter 26e receives the other laser beam demultiplexed from the optical demultiplexer 26d, and transmits this received other laser beam to the second photoreceiver 26l via the first heater 26h.

[0072] The second photoreceiver 26l converts the laser beam (the laser beam resonant with the rear laser beam Lb) filtered by the first optical filter 26e into an electric current. At this time, when the wavelength of the rear laser beam Lb changes, the current value output from the second photoreceiver 26l also changes. Further, the second photoreceiver 26l is electrically connected to the corresponding electrode 26n. For this reason, the second photoreceiver 26l can output a current corresponding to the optical intensity of the other laser beam to the electrode 26n.

[0073] The electrode 26n is disposed around an optical coupling coupler 26c, an optical demultiplexer 26d, optical filters 26e to 26g, heaters 26h to 26j, a first photoreceiver 26k, a second photoreceiver 26l, and a waveguide mirror 26m. The electrode 26n corresponds to the electrode 25f. Note that the electrode 26n constitutes a monitor-side electrode and a connection-use monitor-side electrode.

[0074] Therefore, when mounting the optical monitor 26 on the optical amplifier 25, as shown in FIG. 6, first, the upper surface 25a of the optical amplifier 25 faces upward, and the lower surface 26b of the optical monitor 26 faces upward. Next, as shown in FIGS. 6 and 7, from such a state, the optical monitor 26 is turned over so that the upper surface 26a and the lower surface 26b are in a top-bottom reversed state, and thus the lower surface 26b is mounted on the upper surface 25a of the optical amplifier 25.

[0075] At this time, the optical output coupler 25d and the optical coupling coupler 26c face each other. For this reason, the optical coupling coupler 26c can receive and couple the rear laser beam Lb emitted from the optical output coupler 25d. Also, the electrode 25f and the electrode 26n face each other. The electrode 25f and the electrode 26n are joined to each other using a gold bump, a solder bump, or the like. For this reason, the optical module according to Embodiment 2 can electrically connect the optical amplifier 25 and the optical monitor 26.

[0076] Then, since the optical monitor 26 is turned over and mounted, wire bonding cannot be performed on the electrode 26n that is electrically connected to the first photoreceiver 26k and the second photoreceiver 26l. That is, a current corresponding to the optical intensity of the laser beam cannot be extracted from the electrode 26n that is electrically connected to the first photoreceiver 26k and the second photoreceiver 26l.

[0077] However, in the optical module according to Embodiment 2, the lead wire 25g connects the electrode 25f electrically connected to its electrode 26n and the electrode 25e not covered by the optical monitor 16. Therefore, in the optical module according to Embodiment 2, by bonding the wire 30 to the electrode 25e not covered by the optical monitor 26, a current corresponding to the light intensity of the laser light can be extracted from the electrode 25e.

[0078] Therefore, the optical module according to Embodiment 2 can detect the optical output and oscillation wavelength of the optical amplifier 25 by measuring the current value output from the first light receiver 26k and the current value output from the second light receiver 26l.

[0079] In the optical module according to Embodiment 2, the upper surface 25a of the optical amplifier 25 and the lower surface 26b of the optical monitor 26 are connected so as to face each other and overlap. Therefore, the optical module according to Embodiment 2 can bring the optical amplifier 25 and the optical monitor 26 closer to each other, for example, up to about several tens of μm, without worrying about their mutual contact. As a result, the optical module according to Embodiment 2 can improve the efficiency of optical coupling in the optical monitor 26 without providing the mounting surface of the optical monitor 26 on the pedestal 13.

[0080] As described above, the optical module according to Embodiment 2 includes an optical amplifier 25 having an optical output coupler 25d that emits the rear laser light Lb with the emission of the front laser light Lf from the front end, and an optical monitor 26 having an optical coupling coupler 26c that receives and couples the rear laser light Lb emitted from the optical output coupler 25d. The optical amplifier 25 and the optical monitor 26 are overlapped so that the optical output coupler 25d and the optical coupling coupler 26c face each other. Therefore, the optical module according to Embodiment 2 can efficiently couple the rear laser light Lb emitted from the optical amplifier 25 to the optical monitor 26 without providing a dedicated mounting surface for the optical monitor on the pedestal 13.

[0081] In addition, since the optical module according to Embodiment 2 connects the optical amplifier 25 and the optical monitor 26 so as to face each other and overlap, the pedestal 13 can be made smaller and lighter.

[0082] Embodiment 3. The optical module according to Embodiment 3 will be described with reference to FIGS. 8 to 10.

[0083] FIG. 8 is an enlarged cross-sectional view of the main part of the optical module according to Embodiment 3. FIG. 9 is a plan view of the state before the semiconductor laser 15A and the optical monitor 16A are stacked on top of each other in the optical module according to Embodiment 3. FIG. 10 is a plan view of the state in which the semiconductor laser 15A and the optical monitor 16A are stacked on top of each other in the optical module according to Embodiment 3. Note that components having the same functions as those described in Embodiment 1 described above are denoted by the same reference numerals, and their descriptions are omitted.

[0084] As shown in FIG. 8, the optical module according to Embodiment 3 includes a semiconductor laser 15A and an optical monitor 16A instead of the semiconductor laser 15 and the optical monitor 16 of the optical module according to Embodiment 1.

[0085] As shown in FIG. 9, the semiconductor laser 15A has an upper surface 15a, a lower surface 15b, a laser stripe 15c, an optical output coupler 15d, and a plurality of electrodes 15f. The laser stripe 15c, the optical output coupler 15d, and the plurality of electrodes 15f are provided on the upper surface 15a which is the same plane. The semiconductor laser 15A does not have an electrode 15e. Note that the upper surface 15a constitutes one surface or the other surface, and the lower surface 15b constitutes the other surface or one surface.

[0086] The optical monitor 16A has an upper surface 16a, a lower surface 16b, an optical coupling coupler 16c, an optical demultiplexer 16d, an optical filter 16e, a heater 16f, a first light receiver 16g, a second light receiver 16h, and a plurality of electrodes 16i, 16j. The optical coupling coupler 16c, the optical demultiplexer 16d, the optical filter 16e, the heater 16f, the first light receiver 16g, the second light receiver 16h, and the plurality of electrodes 16j are provided on the upper surface 16a which is the same plane. The plurality of electrodes 16i are provided on the lower surface 16b which is the same plane.

[0087] The electrode 16i corresponds to the electrode 15f of the semiconductor laser 15A. That is, the electrode 15f and the electrode 16i are connected to each other. The electrode 16j is electrically connected to the first light receiver 16g and the second light receiver 16h. Note that the electrode 16j constitutes a monitor side electrode and a monitor side electrode for wire bonding.

[0088] Therefore, when mounting the optical monitor 16A on the semiconductor laser 15A, as shown in FIG. 9, first, the semiconductor laser 15A has the upper surface 15a facing upward, and the optical monitor 16 also has the upper surface 16a facing upward. Next, as shown in FIGS. 9 and 10, from such a state, the optical monitor 16 slides horizontally, and the lower surface 15b is mounted on the upper surface 15a of the semiconductor laser 15.

[0089] At this time, the optical output coupler 15d and the optical coupling coupler 16c face each other. For this reason, the optical coupling coupler 16c can receive and couple the rear laser light Lb emitted from the optical output coupler 15d. Also, the electrode 15f and the electrode 16i face each other respectively. The electrode 15f and the electrode 16i are joined to each other using a gold bump or a solder bump or the like.

[0090] And since the optical monitor 16A is not turned over and mounted, the optical module according to the third embodiment is provided on the upper surface 16a, and the wire 30 can be easily bonded to the electrode 16i that is provided on the upper surface 16a and is electrically connected to the first light receiver 16g and the second light receiver 16h. Therefore, the optical module according to the third embodiment can extract a current corresponding to the optical intensity of the laser light from its electrode 15e. That is, the optical module according to the third embodiment can extract a current corresponding to the optical intensity of the laser light without using the above-described lead wire 15g.

[0091] Therefore, the optical module according to the third embodiment can detect the optical output and oscillation wavelength of the semiconductor laser 15A by measuring the current value output from the first light receiver 16g and the current value output from the second light receiver 16h.

[0092] The optical module according to the third embodiment connects the upper surface 15a of the semiconductor laser 15A and the lower surface 16b of the optical monitor 16A so as to face each other and overlap. Therefore, the optical module according to the third embodiment can bring the semiconductor laser 15A and the optical monitor 16A close to each other, for example, up to about several tens of μm, without worrying about their mutual contact. As a result, the optical module according to the third embodiment can improve the efficiency of optical coupling in the optical monitor 16A without providing the mounting surface of the optical monitor 16A on the pedestal 13.

[0093] As described above, the optical module according to the third embodiment includes a semiconductor laser 15A having an optical output coupler 15d that emits a rear laser light Lb in association with the emission of a front laser light Lf from the front end portion, and an optical monitor 16A having an optical coupling coupler 16c that receives and couples the rear laser light Lb emitted from the optical output coupler 15d. The semiconductor laser 15A and the optical monitor 16A are overlapped such that the optical output coupler 15d and the optical coupling coupler 16c face each other. Therefore, the optical module according to the third embodiment can efficiently couple the rear laser light Lb emitted from the semiconductor laser 15A to the optical monitor 16A without providing a mounting surface dedicated to the optical monitor on the pedestal 13.

[0094] In addition, since the optical module according to Embodiment 3 connects the semiconductor laser 15A and the optical monitor 16A so that they face each other and overlap, the pedestal 13 can be made smaller and lighter.

[0095] Embodiment 4. The optical module according to Embodiment 4 will be described with reference to FIGS. 11 and 12.

[0096] FIG. 11 is a plan view of the state before the optical amplifier 25A and the optical monitor 26A are stacked on top of each other in the optical module according to Embodiment 4. FIG. 12 is a plan view of the state where the optical amplifier 25A and the optical monitor 26A are stacked on top of each other in the optical module according to Embodiment 4. Note that components having the same functions as those described in Embodiments 1 and 2 above are denoted by the same reference numerals, and their descriptions are omitted.

[0097] As shown in FIG. 11, the optical module according to Embodiment 4 includes an optical amplifier 25A and an optical monitor 26A instead of the optical amplifier 25 and the optical monitor 26 of the optical module according to Embodiment 2.

[0098] As shown in FIG. 11, the optical amplifier 25A has an upper surface 25a, a lower surface 25b, an amplification stripe 25c, an optical output coupler 25d, and a plurality of electrodes 25f. The amplification stripe 25c, the optical output coupler 25d, and the plurality of electrodes 25f are provided on the upper surface 25a which is the same plane. The optical amplifier 25A does not have an electrode 25e. Note that the upper surface 25a constitutes one surface or the other surface, and the lower surface 25b constitutes the other surface or one surface.

[0099] The optical monitor 26A has an upper surface 26a, a lower surface 26b, an optical coupling coupler 26c, an optical demultiplexer 26d, a first optical filter 26e, a second optical filter 26f, a third optical filter 26g, a first heater 26h, a second heater 26i, a third heater 26j, a first photoreceiver 26k, a second photoreceiver 26l, a waveguide mirror 26m, and a plurality of electrodes 26n, 26o. The optical coupling coupler 26c, the optical demultiplexer 26d, the optical filters 26e - 26g, the heaters 26h - 26j, the first photoreceiver 26k, the second photoreceiver 26l, the waveguide mirror 26m, and the plurality of electrodes 26o are provided on the upper surface 26a which is the same plane. The plurality of electrodes 26n are provided on the lower surface 26b which is the same plane.

[0100] The electrode 26n corresponds to the electrode 25f of the optical amplifier 25A. That is, the electrode 25f and the electrode 26n are connected to each other. The electrode 26o is electrically connected to the first photoreceiver 26k and the second photoreceiver 26l. Note that the electrode 26o constitutes a monitor - side electrode and a monitor - side electrode for wire bonding.

[0101] Therefore, when mounting the optical monitor 26A on the optical amplifier 25A, as shown in FIG. 11, first, the upper surface 25a of the optical amplifier 25A faces upward, and the upper surface 26a of the optical monitor 26A also faces upward. Next, as shown in FIGS. 11 and 12, from such a state, the optical monitor 26A slides horizontally, and the lower surface 26b is mounted on the upper surface 25a of the optical amplifier 25A.

[0102] At this time, the optical output coupler 25d and the optical coupling coupler 26c face each other. For this reason, the optical coupling coupler 26c can receive and couple the rear laser light Lb emitted from the optical output coupler 25d. Also, the electrode 25f and the electrode 26n face each other respectively. The electrode 25f and the electrode 26n are joined to each other using a gold bump or a solder bump or the like.

[0103] And since the optical monitor 26A is not turned over and mounted, the optical module according to the fourth embodiment is provided on the upper surface 46a and can easily bond the wire 30 to the electrode 26o that is electrically connected to the first light receiver 26k and the second light receiver 26l. Therefore, the optical module according to the fourth embodiment can extract a current corresponding to the optical intensity of the laser light from the electrode 26o. That is, the optical module according to the fourth embodiment can extract a current corresponding to the optical intensity of the laser light without using the above-mentioned lead wire 25g.

[0104] Therefore, the optical module according to the fourth embodiment can detect the optical output and oscillation wavelength of the optical amplifier 25A by measuring the current value output from the first light receiver 26k and the current value output from the second light receiver 26l.

[0105] The optical module according to the fourth embodiment connects the upper surface 25a of the optical amplifier 25A and the lower surface 26b of the optical monitor 26A so as to face each other and overlap. Therefore, the optical module according to the fourth embodiment can bring the optical amplifier 25A and the optical monitor 26A close to each other, for example, up to about several tens of μm, without worrying about their mutual contact. As a result, the optical module according to the fourth embodiment can improve the optical coupling efficiency in the optical monitor 26A without providing the mounting surface of the optical monitor 26A on the pedestal 13.

[0106] As described above, the optical module according to the fourth embodiment includes an optical amplifier 25A having an optical output coupler 25d that emits the rear laser light Lb with the emission of the front laser light Lf from the front end portion, and an optical monitor 26A having an optical coupling coupler 26c that receives and couples the rear laser light Lb emitted from the optical output coupler 25d. The optical amplifier 25A and the optical monitor 26A are overlapped so that the optical output coupler 25d and the optical coupling coupler 26c face each other. Therefore, the optical module according to the fourth embodiment can efficiently couple the rear laser light Lb emitted from the optical amplifier 25A to the optical monitor 26A without providing a mounting surface dedicated to the optical monitor on the pedestal 13.

[0107] In addition, in the optical module according to Embodiment 4, since the optical amplifier 25A and the optical monitor 26A are connected so as to face each other and overlap, it is possible to reduce the size and weight of the pedestal 13.

[0108] Note that within the scope of the present disclosure, any combination of the embodiments, any modification of any component in each embodiment, or any omission of any component in each embodiment is possible.

Industrial Applicability

[0109] In the optical module according to the present disclosure, the rear laser beam Lb can be efficiently coupled by overlapping the laser output section and the optical monitor so that the optical output coupler and the optical coupling coupler face each other, and it is suitable for use in an optical module or the like.

Description of Reference Numerals

[0110] 11 Stem, 11a Main surface, 12 Temperature regulator, 12a Left side surface, 12b Right side surface, 13 Pedestal, 13a Mounting surface, 13b Vertical surface, 14 Submount for semiconductor laser, 15 Semiconductor laser, 15a Upper surface, 15b Lower surface, 15c Laser stripe, 15d Coupler for light emission, 15e, 15f Electrodes, 15g Lead wire, 16 Planar waveguide type optical monitor, 16a Upper surface, 16b Lower surface, 16c Coupler for optical coupling, 16d Optical demultiplexer, 16e Optical filter, 16f Heater, 16g First photoreceiver, 16h Second photoreceiver, 16i, 16j Electrodes, 17 Thermistor, 18 Cap, 19 Window member, 20 Pin, 25 Optical amplifier, 25a Upper surface, 25b Lower surface, 25c Amplification stripe, 25d Coupler for light emission, 25e, 25f Electrodes, 25g Lead wire, 26 Reflective filter integrated optical monitor, 26a Upper surface, 26b Lower surface, 26c Coupler for optical coupling, 26d Optical demultiplexer, 26e First optical filter, 26f Second optical filter, 26g Third optical filter, 26h First heater, 26i Second heater, 26j Third heater, 26k First photoreceiver, 26l Second photoreceiver, 26m Waveguide type mirror, 26n, 26o Electrodes, 30 Wire, Lf Forward laser light, Lb Rearward laser light.

Claims

1. A laser output unit having an optical output coupler that emits rear laser light in accordance with the emission of front laser light from a front end portion, and an optical monitor having an optical coupling coupler that receives and couples the rear laser light emitted from the optical output coupler, wherein the laser output unit and the optical monitor are overlapped such that the optical output coupler and the optical coupling coupler face each other A light module characterized by that.

2. The laser output unit has the optical output coupler and a plurality of laser-side electrodes on the same surface, The optical monitor has the optical coupling coupler and a plurality of monitor-side electrodes on the same surface, The plurality of laser-side electrodes include a plurality of connection laser-side electrodes covered by the optical monitor and connected to the plurality of monitor-side electrodes respectively, and a plurality of wire bonding laser-side electrodes not covered by the optical monitor and not connected to the plurality of monitor-side electrodes, wherein a plurality of connection laser-side electrodes corresponding to the monitor-side electrodes connected to the light receiver of the optical monitor among the plurality of connection laser-side electrodes and the plurality of wire bonding laser-side electrodes are respectively connected by a lead wire The light module according to claim 1, characterized by that.

3. The laser output unit has the optical output coupler and a plurality of laser-side electrodes on the same surface, The optical monitor has the optical coupling coupler and a plurality of monitor-side electrodes, The plurality of monitor-side electrodes include a plurality of wire bonding monitor-side electrodes provided on the surface where the optical coupling coupler is disposed and connected to the light receiver of the optical monitor, and a plurality of connection monitor-side electrodes provided on a surface opposite to the surface where the optical coupling coupler is disposed and connected to the plurality of laser-side electrodes respectively The light module according to claim 1, characterized by that.

4. a stem that supports a temperature regulator for adjusting the temperature of the laser output unit and the temperature of the optical monitor, and a window member through which the front laser light emitted from the laser output unit passes, and a cap provided on the stem so as to cover the laser output unit and the optical monitor from the outside The light module according to any one of claims 1 to 3, characterized by that.

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