Optical module

Abstract

This optical module comprises a carrier (101), two Peltier elements (102a, 102b), and two base members (103a, 103b). An optical element 104 is installed on the carrier (101). The two Peltier elements (102a, 102b) are symmetrically fixed so as to sandwich the carrier (101) in a state in which respective first surfaces contact the carrier (101). The two base members (103a, 103b) are provided so as to respectively sandwich the two Peltier elements (102a, 102b) with the carrier (101).

Description

Optical Module

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

[0002] In optical modules incorporating optical elements such as semiconductor lasers, LiNbO3 (LN), and KTN, temperature control of the optical elements is important to stabilize various optical characteristics such as light wavelength and light intensity, and electrothermal elements such as Peltier elements are often incorporated into the modules. Peltier elements absorb and release heat from one side to the other depending on the direction of the current flow. By controlling the current value using a Peltier element, the temperature of the optical elements can be kept constant.

[0003] A temperature difference between the heat absorption and heat release surfaces of a Peltier element is essential, which results in a temperature distribution within the module. This temperature distribution causes thermal stress and thermal deformation due to differences in the thermal expansion coefficients of the various components within the module, resulting in degradation of optical characteristics and reduced reliability. The impact of thermal deformation is particularly significant in optical elements that are long in the waveguide direction, such as PPLN waveguides, and can cause problems such as damage to optical elements and Peltier elements, separation of joints between components, and increased coupling loss.

[0004] To solve the above-mentioned problems, an optical module incorporating a Peltier element suppresses internal temperature distribution and firmly bonds components together. Instead of directly bonding the optical element to the Peltier element, a carrier member made of a material with a thermal expansion coefficient close to that of the optical element and low thermal resistance is introduced (Patent Document 1). The optical element is bonded to the Peltier element via the carrier member. Furthermore, stress is alleviated by using a thermally conductive adhesive or low-rigidity solder as the bonding material. This configuration suppresses thermal stress and thermal deformation.

[0005] Patent No. 7319582

[0006] However, even if the difference in thermal expansion coefficients between components is reduced, thermal deformation cannot be eliminated in principle, and the problem remains unsolved. Due to the temperature difference between mounting ( FIG. 7A ) and operation ( FIG. 7B ), the difference in thermal expansion coefficients between the Peltier element 302 placed on the base member 301 and the carrier 303 carrying the optical element 304 causes warpage deformation in the carrier 303, resulting in a small angular misalignment of the optical coupling tolerance of the optical element 304 and optical coupling loss. When the optical element 304 is long and large, the above-mentioned effects are severe. For example, stress caused by the difference in thermal expansion coefficients can cause peeling between components or damage to the Peltier element. Alternatively, thermal deformation of the optical element or carrier can cause degradation of optical characteristics, such as increased loss in optical connection to the optical element.

[0007] The present invention has been made to solve the above problems, and has as its object to suppress deformation of a carrier on which an optical element is mounted.

[0008] The optical module according to the present invention comprises a carrier on which an optical element is mounted, two Peltier elements fixed symmetrically on either side of the carrier with their first surfaces in contact with the carrier, and two base members arranged to sandwich each of the two Peltier elements between the carrier and the two base members, and fixed in contact with second surfaces opposite the first surfaces of each of the two Peltier elements.

[0009] As described above, according to the present invention, two Peltier elements are fixed symmetrically across the carrier on which the optical element is mounted, so that deformation of the carrier on which the optical element is mounted can be suppressed.

[0010] FIG. 1 is a perspective view showing the configuration of an optical module according to a first embodiment of the present invention. FIG. 2 is a perspective view showing the configuration of another optical module according to the first embodiment of the present invention. FIG. 3A is a side view showing the configuration of another optical module according to the first embodiment of the present invention. FIG. 3B is a side view showing the configuration of another optical module according to the first embodiment of the present invention. FIG. 3C is a side view showing the configuration of another optical module according to the first embodiment of the present invention. FIG. 4 is a perspective view showing the configuration of another optical module according to the first embodiment of the present invention. FIG. 5 is a perspective view showing the configuration of an optical module according to a second embodiment of the present invention. FIG. 6 is a perspective view showing the configuration of another optical module according to the second embodiment of the present invention. FIG. 7A is an explanatory diagram showing the state of a carrier 303 on which an optical element 304 is mounted during mounting. FIG. 7B is an explanatory diagram showing the state of a carrier 303 on which an optical element 304 is mounted during operation.

[0011] An optical module according to an embodiment of the present invention will now be described.

[0012] First Embodiment First, an optical module according to a first embodiment of the present invention will be described with reference to FIG.

[0013] This optical module includes a carrier 101, two Peltier elements 102a and 102b, and two base members 103a and 103b. The carrier 101 carries an optical element 104. The carrier 101 has an outer shape of, for example, a rectangular parallelepiped, and the optical element 104 is mounted on the rectangular upper surface with the largest area, and is arranged so that the longitudinal direction of the carrier 101 roughly coincides with the optical waveguide direction of the optical element 101.

[0014] The two Peltier elements 102a, 102b are fixed symmetrically across the carrier 101, with their first surfaces in contact with the carrier 101. The two Peltier elements 102a, 102b are arranged with their first surfaces facing each other across the carrier 101. For example, the first surfaces are heat absorption surfaces of the Peltier elements, and the heat absorption surfaces of the Peltier elements 102a, 102b are fixed in contact with the carrier 101. For example, the two Peltier elements 102a, 102b are fixed to each of the side surfaces 101b, 101c in the longitudinal direction of the top surface 101a of the rectangular parallelepiped carrier 101. For example, they can be fixed using an adhesive, solder, or silver paste.

[0015] Each of the two base members 103a, 103b is disposed so as to sandwich each of the two Peltier elements 102a, 102b between itself and the carrier 101. The base members 103a, 103b are fixed in contact with a second surface of each of the two Peltier elements 102a, 102b opposite the first surface thereof. For example, the base members 103a, 103b are fixed in contact with the heat dissipation surfaces of the Peltier elements 102a, 102b. For example, they can be fixed using an adhesive, solder, or silver paste.

[0016] 2, a set of two Peltier elements 102a and 102b, a set of two Peltier elements 102c and 102d, and a set of two Peltier elements 102e and 102f can be provided at multiple locations on the carrier 101. In this example, the above-mentioned sets of Peltier elements are provided at multiple locations on each of the side surfaces 101b and 101c of the carrier 101 in the longitudinal direction.

[0017] For example, the Peltier elements 102c, 102a, and 102e can be arranged at equal intervals. Similarly, the Peltier elements 102d, 102b, and 102f can be arranged at equal intervals. Furthermore, the Peltier elements 102c and 102e can be arranged symmetrically with the Peltier element 102a in between. Similarly, the Peltier elements 102d and 102f can be arranged symmetrically with the Peltier element 102b in between. In this example, three sets are provided, but this is not limited thereto, and two sets, or four or more sets can be provided.

[0018] As described above, by arranging the two Peltier elements 102a and 102b opposite each other (facing each other) across the carrier 101 and arranging them in symmetrical locations, the direction of the stress generated in the carrier 101 and other parts by the operation of the Peltier elements is reversed and canceled, thereby suppressing deformation of the carrier 101.

[0019] Furthermore, by providing multiple sets of Peltier elements in the longitudinal direction of the carrier 101, it is possible to suppress deformation of the long carrier 101. Furthermore, it is possible to reduce the stress per set of two Peltier elements, thereby suppressing damage such as peeling of the Peltier elements.

[0020] As shown in FIG. 3A , the two Peltier elements 102 a and 102 b can be provided on two opposing side surfaces adjacent to the mounting surface of the carrier 101 on which the optical element 104 is mounted. This configuration makes the carrier 101 less susceptible to structural deformation and facilitates mounting the optical element 104 on the carrier 101. Furthermore, since the optical axis of the optical element 104 can be positioned near the axis of symmetry of the two Peltier elements 102 a and 102 b, the effects of thermal deformation on the optical characteristics of the optical element, such as optical coupling loss, can be reduced. As shown in FIG. 3B , the Peltier elements 102 a and 102 b can be provided on the mounting surface (top surface) of the carrier 101 on which the optical element 104 is mounted and on the back surface facing the mounting surface. Furthermore, as shown in FIG. 3C , the base member can be divided and provided for each set.

[0021] Furthermore, the carrier 101 and the two base members 103a, 103b can be made of the same material. By configuring them in this way, the absolute values ​​of the expansion and contraction amounts of the heat absorption surface side and the heat dissipation surface side of each of the two Peltier elements 102a, 102b can be matched, and the stress applied to the two Peltier elements 102a, 102b can be reduced.

[0022] Incidentally, this optical module is housed in a package 105 for use, as shown in Fig. 4. For example, predetermined surfaces of the base members 103a and 103b can be fixed to the inner surface of the package 105 in a low thermal resistance state using a heat-conductive adhesive, solder, silver paste, or the like. The carrier 101 does not contact the package 105. Although not shown in Fig. 4, optical components such as optical fibers and lenses for inputting and outputting light to and from the optical element 104, as well as a multiplexer and demultiplexer as disclosed in Patent Document 1, are also housed in the package 105 and arranged so as to be optically coupled to the optical element 104.

[0023] [Embodiment 2] Next, an optical module according to embodiment 2 of the present invention will be described with reference to Figure 5. This optical module further includes a connecting member 103c that connects two base members 103a and 103b. The two base members 103a and 103b are connected by the connecting member 103c to form an integrated structure. For example, the two base members 103a and 103b are connected by the connecting member 103c on the bottom side of the carrier 101. The other configuration is the same as that of embodiment 1 described above. Note that the bottom surface of the carrier 101 and the connecting member 103c do not contact each other. It is desirable that the two base members 103a and 103b and the connecting member 103c are made of the same material.

[0024] According to the second embodiment, the amount of deformation of the base members 103 a and 103 b can be suppressed. In addition, the temperatures of the base members 103 a and 103 b of each Peltier element can be made the same, thereby suppressing distortion caused by temperature differences.

[0025] In order to assemble and secure the Peltier element 102 and carrier 101 in a state in which the two base members 103a, 103b and the connecting member 103c are connected in advance, high precision is required in the shape and assembly of each component, making the mounting work difficult. Therefore, a method in which the two base members 103a, 103b, the Peltier element 102, and the carrier 101 are assembled and then the connecting member 103c is connected is desirable. Furthermore, instead of preparing a new connecting member 103c, the package 105 can also be used as a connecting member, and the base members 103a, 103b can be fixed directly to the bottom surface inside the package, thereby achieving the same effect as using the connecting member 103c while reducing the number of components.

[0026] Furthermore, when two base members 103a, 103b are connected by connecting member 103c to form an integrated structure, the integrated base members 103a, 103b and connecting member 103c are housed and fixed to the inner bottom surface of package 105 by the bottom surface of connecting member 103c. As shown in Figure 6, a compensation member 106 can be provided in package 105 that houses these. Compensation member 106 is provided in contact with the outer bottom surface of package 105, facing the inner bottom surface of package 105 that contacts connecting member 103c. Connecting member 103c and compensation member 106 can be made of the same material.

[0027] For example, in the normal direction to the top surface of carrier 101, the center of the top surface of carrier 101, the center of connecting member 103c, and compensation member 106 can be arranged on the same line. Furthermore, the respective planar shapes in a direction parallel to the top surface of carrier 101 can be centrosymmetric. Furthermore, the planar shape of compensation member 106 in a direction parallel to the top surface of carrier 101 can be the same shape (same area) as connecting member 103c. Furthermore, the thickness of compensation member 106 and the thickness of connecting member 103c in the normal direction to the top surface of carrier 101 can be the same.

[0028] The compensating member 106 can suppress deformation of the package 105 caused by the difference in thermal expansion between the connecting member 103c and the package 105. If the compensating member 106 is not used, the difference in thermal expansion between the connecting member 103c and the package 105 may cause the connecting member 103c and the package 105 to deform in a direction that causes the two base members 103a and 103b to pull the two Peltier elements 102a and 102b away from the carrier 101. This deformation may damage the Peltier elements 102a and 102b and cause the bonding surfaces with the base members 103a and 103b to peel off.

[0029] In contrast, by providing the compensating member 106, stresses due to the difference in thermal expansion between the inner and outer surfaces of the bottom surface of the package 105 to which the connecting member 103c is fixed are caused to act in such a way as to cancel each other out, thereby suppressing deformation of the connecting member 103c and the package 105 due to the difference in thermal expansion, and suppressing damage and peeling of the Peltier elements 102a and 102b.

[0030] As described above, according to the embodiment of the present invention, two Peltier elements are fixed symmetrically on either side of the carrier carrying the optical element, thereby making it possible to suppress deformation of the carrier carrying the optical element.

[0031] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be made by a person having ordinary knowledge in the art within the technical concept of the present invention.

[0032] 101...carrier, 102a, 102b...Peltier elements, 103a, 103b...base members, 104...optical element.

Claims

1. An optical module comprising: a carrier on which an optical element is mounted; two Peltier elements fixed symmetrically on either side of the carrier with their first surfaces in contact with the carrier; and two base members arranged to sandwich each of the two Peltier elements between the carrier and the two base members, and fixed in contact with a second surface of each of the two Peltier elements opposite the first surface.

2. An optical module according to claim 1, wherein the two sets of Peltier elements are provided at a plurality of locations on the carrier.

3. An optical module according to claim 1, wherein the carrier and the two base members are made of the same material.

4. An optical module according to claim 1, further comprising a connecting member for connecting said two base members.

5. An optical module according to claim 4, comprising a package that houses the optical element, the carrier, the two Peltier elements, the two base members, and the connecting member, and further comprising a compensation member provided in contact with the outer bottom surface of the package facing the inner bottom surface of the package that contacts the connecting member.

6. An optical module according to claim 5, wherein the connecting member and the compensating member are made of the same material.

7. An optical module according to any one of claims 1 to 6, wherein the two Peltier elements are provided on two opposing side surfaces of the carrier adjacent to the mounting surface on which the optical element is mounted.

8. An optical module according to any one of claims 1 to 6, wherein the two Peltier elements are provided on a mounting surface of the carrier on which the optical element is mounted and on a back surface opposite the mounting surface.

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