Optical modulator and optical transmission apparatus using the same

Abstract

Provided is an optical modulator in which poor welding between a housing main body and a cover portion is suppressed. An optical modulator includes a housing that houses an optical waveguide element in a rectangular parallelepiped, characterized in that the housing includes a housing main body (1) in which one face of the rectangular parallelepiped is an open portion, and a rectangular cover portion (2) that plugs the open portion, the cover portion has a thin thickness at a peripheral portion, a protruding portion (20) that protrudes toward the inside of the housing is formed in the cover portion except for the peripheral portion, and when the cover portion is fitted into the housing main body, the distance between the inner periphery of the end face of the housing main body that forms the open portion and the outer end portion of the protruding portion is set so that the distance (d1) formed on the short side of the cover portion is greater than the distance (d2) formed on the long side of the cover portion.

Description

Technical Field

[0001] The present invention relates to an optical modulator and an optical transmission device using the optical modulator, and particularly to an optical modulator having a cuboid housing that accommodates at least an optical waveguide element, the housing having a housing body having one side of the cuboid as an opening and a rectangular cover that blocks the opening. Background Technology

[0002] In the fields of optical communication or optical measurement, optical modulators are often used. These modulators utilize optical waveguide elements, which have an optical waveguide and modulation electrodes that modulate the light waves propagating in the optical waveguide. As shown in Patent Document 1, a typical optical modulator mounts the optical waveguide element (a chip forming an optical waveguide and modulation electrodes, etc.), optical components, electronic components, etc., inside a metal housing, which is then hermetically sealed by a metal cover.

[0003] The housing is mostly rectangular in shape. On the side wall of the housing, for example on the short side, there is an optical fiber guide or optical window for optical input and output, and on the long side, there is a high-frequency connector or pin for input and output of electrical signals.

[0004] An opening is formed in the upper (or lower) part of the metal casing for a metal cover. The metal casing and a portion of the cover are welded together around the circumference by seam welding (resistance welding) to achieve an airtight seal. The welded portion undergoes a surface treatment with a metal plating such as Au or Ni. Furthermore, to mitigate the (thermal) stress generated by the seam welding, a low-melting-point brazing filler metal is sometimes placed between the casing and the cover before seam welding.

[0005] Figure 1 This is a diagram showing an example of a shell. Figure 1 (a) is a top view of the shell. Figure 1 (b) is Figure 1 (a) Sectional view at the single-dotted dashed line A-A'. Figure 1 (c) shows Figure 1 (a) Cross-sectional view at the dashed line B-B'. The cover 2 is arranged to block the opening of the housing body 1.

[0006] The cover 2 has a protruding portion 20 that protrudes into the inner side of the housing body 1. The cover 2 that contacts the end face 10 of the housing body forming the opening is thin, while the protruding portion 20 of the cover at the opening is thick. By inserting (falling into) the protruding portion 20 of the cover into the opening of the housing 1, it is easy to adjust the position of the housing body 1 and the cover 2 before seam welding. Moreover, during seam welding, it is possible to prevent the position of the cover from deviating due to contact with the roller electrode.

[0007] By reducing the distance (short side clearance d1, long side clearance d2) between the inner wall of the opening of the housing body 1 (the inner periphery 10L of the end face 10 forming the opening) and the outer end 20L of the protruding portion 20 of the cover, the accuracy of position adjustment can be improved, and the effect of preventing position deviation can be enhanced. Conventionally, this clearance is usually set to be constant (d1 = d2) throughout the entire circumference of the opening of the housing body.

[0008] In addition, regarding the cover used in optical devices such as optical modulators in the prior art, considering productivity or cost factors, a metal plate (SUS304 or Kovar alloy, etc.) with a thickness of about 0.3 to 0.5 mm is etched to thin the outer periphery of the metal plate to about 0.1 mm, thereby forming the protruding part 20 of the cover 2.

[0009] The raised portion is formed by etching, thus creating a layer at the interface between the thick and thin parts of the cover. Figure 2 Such a sloping portion (side edge) R. The thicker the etching, the larger the size of the sloping portion. Therefore, if you want to reduce the size of the sloping portion, you can reduce the original board thickness by making the etching thickness thinner.

[0010] As described above, in order to adjust the positions of the housing body 1 and the cover 2, the gap (d1, d2) between the inner wall (inner periphery 10L) of the opening of the housing and the outer end 20L of the protruding portion of the cover is set to be constant (d1 = d2) throughout the entire circumference of the opening of the housing body, thereby reducing the gap (d1, d2). Specifically, the gap (d1, d2) between the inner wall (inner periphery 10L) of the opening of the housing and the outer end 20L of the protruding portion of the cover is set to a size of 0.2 to 0.5 mm.

[0011] Seam welding is a technique that involves applying pressure to the outer periphery of the cover portion 2 using two parallel roller electrodes, while simultaneously energizing the roller electrodes and continuously welding the contact portion between them to the cover portion. It is used for airtight sealing of products requiring high airtightness, such as optical devices. Figure 3 (a) is a diagram showing the situation near the unilateral roller electrode RE. Through the energization between the roller electrodes, the contact portion between the roller electrode RE and the cover 2 heats up (due to high contact resistance), reaching a high temperature. The metal at the contact portion and its vicinity (including surface-treated metal plating such as Au or Ni) melts, thereby welding the cover 2 to the housing body 1. It should be noted that the actual roller electrode used is larger than the structure shown in the diagram, and the size of the housing, etc., is larger.

[0012] During seam welding, the contact area between the roller electrode and the cover 2 heats up, thus the entire cover becomes very hot (although it is also affected by welding conditions such as current value, as well as the size of the cover or the main body of the shell, but is, for example, around 100 to 200°C). Due to heat transfer from the welding part or the contact area between the roller electrode and the cover 2, the main body of the shell is also heated, but a temperature difference is generated between the cover and the metal shell.

[0013] Before seam welding, such as Figure 3 (a) In this way, there is no gap between the end face 10 of the opening of the housing 1 and the cover 2, and the cover is pressurized by the roller electrode RE. If seam welding is performed in this state, the housing body and the cover are properly welded together to achieve an airtight seal.

[0014] However, as the seam welding begins, the entire cover gradually reaches a high temperature, causing its dimensions to increase due to thermal expansion. As a result, as... Figure 3 (b) In this way, the inclined portion R of the cover moves upward to the side wall of the housing 1, creating a gap between the end face 10 of the opening of the housing 1 and the cover 2. Figure 3 (b) The arrow EX indicates the direction of thermal expansion.

[0015] If a gap is formed between the end face 10 of the opening of the main body of the housing and the cover 2, then as Figure 4 As shown, by applying pressure F to the roller electrode RE, a portion of the cover 2 deforms with the contact point FU between the housing body 1 and the inclined portion R of the cover 2 as the fulcrum. Due to the deformation of the cover 2, the contact area between the roller electrode RE and the contact portion C of the cover 2 increases. The increase in contact area reduces the contact (electrical) resistance between the roller electrode RE and the cover 2. Since the current flow between the roller electrodes is constant, the heat generated at the contact portion C between the roller electrode RE and the cover 2 is reduced. As a result, the temperature at and around the contact portion C does not reach the melting point of the metal (including surface-treated metal plating such as Au or Ni), resulting in insufficient welding (poor weld).

[0016] Furthermore, even assuming that the metal in and around the contact portion C melts, the gap between the end face 10 of the opening of the housing body and the cover portion 2 is large, so the housing body and the cover portion are not completely welded, resulting in insufficient airtight seal.

[0017] The deformation of cover 2 caused by the upward movement of the inclined portion R of cover 2 towards the side wall of the housing body 1 is as follows: Figure 4As shown, when the width W1 of the end face 10 of the opening of the housing body where the housing body connects to the cover is narrow (specifically, less than 1.5 mm), and the length L from the aforementioned fulcrum FU to the front end of the cover 2 is short, the degree of deformation (bending) of the cover 2 is large. Furthermore, when the gap between the end face 10 of the opening of the housing body and the cover 2 is the same, the shorter the length L, the greater the degree of deformation. When the degree of deformation increases, the contact area between the roller electrode RE and the contact portion C of the cover 2 increases, thus making poor welding (defects) more likely to occur.

[0018] In optical devices such as optical modulators that use rectangular housings, in order to reduce the deformation of the housing body 1 and the cover 2 caused by seam welding, according to... Figure 5 The steps shown are for seam welding. Preferably, spot welding is first performed on the center S of the long side of the shell, welding proceeds from the center of the long side toward both ends, and finally welding is performed on the short side. This is because if the short side is welded first, the extension of the cover caused by thermal expansion in the long side direction (X direction) is hindered, resulting in greater (thermal) stress. Figure 5 In (a), the circular numbers indicate the welding sequence and direction. Figure 5 (b) is a cross-sectional view showing the weld as viewed from the short side (X direction) of the shell. Figure 5 (c) is a cross-sectional view viewed from the long side (Y direction). It should be noted that... Figure 5 In (a), the seam welding of the long side of the shell is carried out in two stages, but when the length of the long side is large, the seam welding is sometimes carried out in further segments.

[0019] exist Figure 5 In the welding process shown, during the seam welding of the long side, the cover 2 extends due to thermal expansion, and the short sides on both sides of the main body 1 become... Figure 3 (b) and Figure 4 In such a state, the short sides of the shell are prone to insufficient welding (defects). Although it is also affected by the seam welding conditions, the longer the long side of the shell, the longer the welding time (the longer the heating time), and the greater the extension of the cover due to thermal expansion. Therefore, it tends to have insufficient welding (defects) on the short sides. It should be noted that during the seam welding of the long side, the short side direction (Y direction) of the cover is also affected by thermal expansion. However, since the length of the short side of the cover is shorter than the length of the long side, the extension of the cover in the short side direction (Y direction) is smaller than the extension in the long side direction (X direction). Moreover, the welding of the cover 2 to the long side of the shell body 1 is completed before the extension in the short side direction increases, so the long side ( Figure 5 (a) Arrows 1 and 2) indicate insufficient (poor) welding.

[0020] Prior art literature

[0021] Patent documents

[0022] Patent Document 1: Japanese Patent Application Publication No. 7-198997 Summary of the Invention

[0023] Summary of the invention

[0024] The problem that the invention aims to solve

[0025] The problem to be solved by the present invention is to solve the aforementioned problems and to provide an optical modulator that suppresses poor welding between the housing body and the cover, and an optical transmitting device using the optical modulator.

[0026] Solution for solving the problem

[0027] In order to solve the above-mentioned problems, the optical modulator and optical transmission device of the present invention have the following technical features.

[0028] (1) An optical modulator comprising a cuboid housing that accommodates at least an optical waveguide element, characterized in that the housing comprises a housing body having one side of the cuboid as an opening and a rectangular cover portion blocking the opening, the peripheral portion of the cover portion being thin, and, except for the peripheral portion, forming a protruding portion protruding toward the interior of the housing, wherein when the cover portion is inserted into the housing body, the distance between the inner periphery of the end face of the housing body forming the opening and the outer end of the protruding portion is set such that the distance formed on the short side of the cover portion is greater than the distance formed on the long side of the cover portion.

[0029] (2) In the light modulator described in (1) above, the side of the convex portion of the cover has an inclined portion that is inclined toward the peripheral portion.

[0030] (3) In the optical modulator described in (1) or (2) above, the thickness of the peripheral portion of the cover is less than 0.2 mm.

[0031] (4) In any of the optical modulators described in (1) to (3) above, the thickness of the convex portion of the cover is 0.2 mm or more and 1 mm or less.

[0032] (5) In any of the optical modulators described in (1) to (4) above, the opening of the housing body is formed by the side wall of the housing surrounding the opening or a sealing member different from the side wall.

[0033] (6) In any of the optical modulators described in (1) to (5) above, the housing body and the cover are sealed by seam welding.

[0034] (7) In any of the optical modulators described in (1) to (6) above, the characteristic is that a driving circuit element is disposed adjacent to the optical waveguide element, the driving circuit element generating an electrical signal applied to the modulation electrode in the optical waveguide element.

[0035] (8) An optical transmitting apparatus, characterized in that it comprises an optical modulator and a signal generator described in any of (1) to (7) above, wherein the signal generator generates a modulation signal input to the driving circuit element.

[0036] Invention Effects

[0037] In an optical modulator comprising a cuboid housing containing at least an optical waveguide element, the present invention includes a housing body having one side of the cuboid as an opening and a rectangular cover blocking the opening. The peripheral portion of the cover is thin, and except for the peripheral portion, a convex portion protruding toward the interior of the housing is formed on the cover. When the cover is inserted into the housing body, the distance between the inner periphery of the end face of the housing body forming the opening and the outer end of the convex portion is set such that the distance formed on the short side of the cover is larger than the distance formed on the long side of the cover. Therefore, during the welding of the housing body and the cover, even if the elongation in the long direction increases due to thermal expansion, no gap is formed between the end face of the housing body forming the opening and the cover, thus suppressing the occurrence of welding defects. Attached Figure Description

[0038] Figure 1 These are diagrams illustrating the shell of a cuboid. (a) is a top view, (b) is a cross-sectional view at point A-A' in (a), and (c) is a cross-sectional view at point B-B' in (a).

[0039] Figure 2 This is a diagram showing the shape near the end of the cover.

[0040] Figure 3 The diagram shows the situation of the welded part during seam welding. (a) shows the situation when the elongation caused by thermal expansion is small, and (b) shows the situation when the elongation caused by thermal expansion is large.

[0041] Figure 4 This diagram illustrates the deformation that occurs at the end of the cover during seam welding.

[0042] Figure 5 The diagrams show the steps involved in seam welding a cuboid shell. (a) is a top view, (b) is a cross-sectional view from the short side, and (c) is a cross-sectional view from the long side.

[0043] Figure 6The figures show an example of a housing in which an opening in the main body of the housing is formed by a sealing member SL. (a) is a top view, (b) is a cross-sectional view of (a) along the single-dotted line A-A', and (c) is a cross-sectional view of (a) along the single-dotted line B-B'.

[0044] Figure 7 This is a diagram showing the positional relationship between the roller electrode and the pins during seam welding in an optical modulator with pins extending to the bottom side of the housing body.

[0045] Figure 8 This is a diagram showing the positional relationship between the roller electrode and the pin during seam welding in an optical modulator with pins extending towards the cover side of the housing.

[0046] Figure 9 This is a diagram illustrating the optical transmitting apparatus of the present invention. Detailed Implementation

[0047] Hereinafter, the present invention will be described in detail using preferred embodiments.

[0048] like Figure 1 As shown, the present invention relates to an optical modulator comprising a cuboid housing for at least accommodating an optical waveguide element, characterized in that the housing comprises a housing body 1 having one side of the cuboid as an opening and a rectangular cover 2 blocking the opening, the peripheral portion of the cover being thin, and except for the peripheral portion, a protrusion 20 protruding toward the interior of the housing is formed on the cover. When the cover is inserted into the housing body, the end face 10 of the housing body forming the opening (in...) Figure 1 In case (b), the distance between the inner periphery of the uppermost surface of the side wall of the housing body 1 and the outer end of the convex portion is set such that the distance d1 formed on the short side of the cover is greater than the distance d2 formed on the long side of the cover.

[0049] As described above, when a rectangular shell is hermetically sealed by welding, the cover extends due to thermal expansion caused by welding on the long side, and the cover extends upwards onto the side wall of the shell body. This can easily lead to insufficient welding (defects) when welding on the short side of the shell. Therefore, in this invention, the short side of the shell is designed such that the gap d1 between the inner wall of the opening of the shell body and the convex portion of the cover is larger than the gap d2 on the long side (d1>d2).

[0050] As the material for the housing, metals such as SUS304 and Kovar alloy are used. The housing body can be formed integrally from a single metal raw material through machining, or multiple components manufactured through machining or stamping can be combined to form a housing. The choice of method is determined by factors such as housing size or function, productivity or cost. The housing body and the cover can be formed from the same material or from different materials. The surfaces of the housing and the cover, which are the welded parts of the housing body and the cover, can be surface treated by plating with metals such as Au or Ni. Moreover, as the housing used in this invention, ceramic materials can be used in a part of the housing body, as in integrated small optical devices such as HB-CDM (High Bandwidth Coherent Driver Modulator), which combines an optical waveguide element with a driving circuit element that drives the optical waveguide element, as described later.

[0051] Regarding the cover, it uses metal materials (SUS304, Kovar alloy, etc.) and has... Figure 1 The convex portion 20 is shown. As a method for forming the convex portion (the peripheral portion of the cover is formed thin), cutting or electron beam processing can also be used, but for low-cost and stable formation, etching can be used to make the peripheral portion of the cover thin. When using etching, such as... Figure 2 As shown, the side surface R of the protruding portion 20 of the cover 2 is inclined towards the periphery of the cover. This inclined surface is referred to as the "inclined portion". As described above, this is also the reason why the inclined portion of the cover extends upward toward the side wall of the housing body.

[0052] On the other hand, in order to weld the cover to the main body of the housing, the thickness of the peripheral portion of the cover needs to be set to be 0.05 mm or more and less than 0.2 mm. Taking into account the rigidity that varies with the size of the cover or the time required for etching, the thickness of the cover (the thickness 20H of the thicker portion of the protrusion 20) is set to a range of 0.2 to 1 mm. More preferably, it is set to 0.3 to 0.5 mm.

[0053] Regarding the specific dimensions of gaps d1 and d2, for example, when using a cover made of SUS304 with a length of 100mm and a width of 15mm, considering the amount of extension of the cover due to thermal expansion that can be calculated based on the temperature change of the cover caused by the seam welding, as well as the dimensional tolerances or installation accuracy of each component (body and cover), d1 is set to approximately 0.6 to 1mm, and d2 is set to 0.3 to 0.5mm. By setting the gap d1 to be large, it is possible to prevent the tilted portion of the cover from rising onto the side wall of the body, thus preventing insufficient welding (defects). Furthermore, by setting the gap d2 to be narrow as always, the accuracy of the position adjustment before seam welding can be maintained, thus preventing the cover from deviating from its position during seam welding.

[0054] The optical modulator of the present invention can also be applied to Figure 6 The case shown illustrates where the opening in the housing body is formed by a sealing member SL surrounding the opening. Figure 6 In, such as the bottom surface that constitutes the shell (in Figure 6 (b) and (c) describe the portion disposed on the lower side. However, when disposed on a printed circuit board (PCB), there are cases where the bottom surface faces the PCB side. There are also cases where other surfaces, for example... Figure 6 (b) and (c) are cases where the upper portion faces the printed circuit board. 1B, like the side components (1A, 1C), are assembled from multiple components to form the main body of the housing. The components (1A, 1B, and 1C) are joined by a metal such as AuSn. The components can be made of the same material or different materials. For example, component 1A is ceramic, while components 1B and 1C are metals (Kovar alloy, CuW, etc.).

[0055] Since the ceramic component 1A is not directly seam-welded, a sealing member (sealing ring) SL for seam welding is provided on the end face of the opening side of the housing when such a ceramic component is included. The surface of the sealing member (sealing ring) is plated with metal (Au, Ni, etc.) for joining the sealing member to the ceramic component and seam welding the sealing member to the cover. The sealing member (sealing ring) is joined to the ceramic component or other components by metal, and the newly formed opening by the sealing member (sealing ring) is blocked by the cover 2 made of metal, etc., achieving an airtight seal through seam welding. The material of the sealing member (sealing ring) SL is usually the same as that of the cover 2, but this varies depending on the purpose. Furthermore, sometimes a low-melting-point brazing filler metal or the like is placed between the sealing member (sealing ring) SL and the cover 2 for seam welding.

[0056] exist Figure 6 In optical devices such as HB-CDMs using ceramic housings, the dimensions of the housing and cover are smaller than those of conventional optical devices. Therefore, the elongation of the cover due to thermal expansion is smaller, and the risk of insufficient welding (defects) caused by the upward movement of the cover's inclined portion is reduced. However, when using the sealing member SL, the width of the uppermost part of the opening of the sealing member SL (equivalent to that in a metal housing) Figure 4 The width W1 is narrowed to about 0.5 to 1.0 mm, and the length L from the fulcrum FU of the cover to the front end of the cover 2 tends to become shorter. Furthermore, corresponding to the width of the uppermost part of the opening of the sealing member, the width of the thinner portion of the peripheral part of the cover itself ( Figure 2 The symbol W also tends to narrow. Therefore, when using the sealing member SL, the deformation of the peripheral portion of the cover is greater than that of the metal shell. Figure 1(Except for) it is easy to occur. In order to suppress it, as in the light modulator of the present invention, the gap d1 on the short side can be set to be larger than the gap d2 on the long side regarding the distance (gap, d1 and d2) between the inner wall of the opening of the sealing member and the convex part of the cover.

[0057] In optical devices such as HB-CDM, an integrated optical device (optical modulator) has been proposed, which combines an optical waveguide element with a driving circuit element that drives the optical waveguide element. In such an integrated optical device, the following is used... Figure 6 Such a shell is made by combining ceramics and metal. Figure 7 This is a structure commonly used in conventional optical modulators, featuring electrical connection terminals (pins P1 or P2). The housing is mounted on a printed circuit board, and the electrical connection terminals are soldered to the printed circuit board. Therefore, the solder connection portion of the electrical connection terminals is located on the bottom side of the housing. Figure 7 (The lower side). Figure 7 In that case, interference between the roller electrode RE and the pin does not occur, and seam welding will not be a particular problem.

[0058] In contrast, in the case of integrated optical devices, it is necessary to dissipate the heat generated by the drive circuit components mounted inside the housing to heat-absorbing devices located outside the housing. Since part of the housing is made of ceramic with low thermal conductivity, or the drive circuit and the cover are not in contact (an air layer exists between them), heat dissipation efficiency from the cover side is low. Therefore, it is necessary to dissipate heat from the bottom surface of the housing (… Figure 8 The lower side is configured as a heat dissipation surface for the drive circuit components, and the cover side is configured as a mounting surface for mounting onto the printed circuit board. In such a case, as... Figure 8 As shown, the solder joint of the electrical connection terminal (pin P1 or P2) is located on the cover side.

[0059] exist Figure 8 In such a configuration, the outer periphery of the cover is close to (a portion of) the electrical connection terminal, and the distance G (from the end of the cover to the electrical connection terminal) between them may be less than 2 mm. Therefore, during seam welding, the roller electrode RE comes into contact with the electrical connection terminal (P1 or P2), sometimes causing damage to the terminal. This contact occurs particularly when the position of the roller electrode RE changes due to the offset of the cover 2, causing a change in its height or lateral position. To avoid this, by reducing the gap between the opening of the sealing member (sealing ring) and the protrusion of the cover (d2 in the case of a pin positioned on the long side), for example, by setting the gap d2 to 0.3 mm or less, it is possible to suppress the offset of the cover during seam welding and prevent damage to the electrical connection terminal.

[0060] It should be noted that while seam welding has been described so far as an example of an airtight seal, the sealing method is not limited to this; other methods such as laser welding can also be used.

[0061] Figure 9 This is a diagram illustrating an example of an optical transmitting device.

[0062] In an optical modulator, a drive circuit element DRV that generates an electrical signal Sout applied to the modulation electrodes of the optical waveguide element is disposed adjacent to the optical waveguide element OE. The optical waveguide element OE and the drive circuit element DRV are housed in the same housing CS. The optical waveguide element OE uses optical fiber FB, and the input light Lin is input to the optical waveguide OW formed on the optical waveguide element via optical components such as lenses. On the other hand, light waves emitted from the optical waveguide element OE are combined, for example, by a polarization wave synthesizing unit PC, and input to another optical fiber via optical components such as lenses, becoming the output light Lout.

[0063] Alternatively, a signal generator (DSP) can be installed to generate the modulation signal Sin input to the drive circuit element DRV, thus configuring it as an optical transmission device. The housing CS and the signal generator DSP can also be housed in a single enclosure.

[0064] Industrial availability

[0065] As described above, according to the present invention, it is possible to provide an optical modulator that suppresses poor welding between the housing body and the cover, and an optical transmitting device using the optical modulator.

[0066] Explanation of reference numerals in the attached figures

[0067] 1. Shell Body

[0068] 10. End face of the sidewall (sealing member) forming the opening of the housing

[0069] 2 cover

[0070] 20. The raised portion of the cover

[0071] The side edge (inclined surface) of the R-shaped convex portion

Claims

1. An optical modulator comprising a cuboid housing housing at least one optical waveguide element, characterized in that, The shell has a main body that has one side of the cuboid as an opening and a rectangular cover that blocks the opening. The peripheral portion of the cover is thin, and apart from this peripheral portion, a convex portion protruding towards the interior of the housing is formed on the cover. When the cover is embedded in the housing body, the distance between the inner periphery of the end face of the housing body forming the opening and the outer end of the protruding portion is set such that the distance formed on the short side of the cover is greater than the distance formed on the long side of the cover. The main body of the housing and the cover are sealed by seam welding. The side of the convex portion of the cover has an inclined portion that slopes toward the peripheral portion.

2. The optical modulator according to claim 1, characterized in that, The thickness of the peripheral portion of the cover is less than 0.2 mm.

3. The optical modulator according to claim 1 or 2, characterized in that, The thickness of the convex portion of the cover is 0.2 mm or more and 1 mm or less.

4. The optical modulator according to claim 1 or 2, characterized in that, The opening of the housing body is formed by the side wall of the housing surrounding the opening itself or by a sealing member different from the side wall.

5. The optical modulator according to claim 1 or 2, characterized in that, A driving circuit element is disposed adjacent to the optical waveguide element, which generates an electrical signal applied to the modulation electrode within the optical waveguide element.

6. An optical transmitting device, characterized in that, The optical modulator and signal generator according to any one of claims 1 to 5, wherein the signal generator generates a modulated signal input to the driving circuit element.

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