Optical device and optical transmitter using the same

Abstract

To provide an optical device that can be miniaturized by suppressing electrical short circuit between lead pins arranged on the side surface of a housing and a lid member.SOLUTION: In an optical device including a housing that at least accommodates an optical waveguide element, a main body 1 of the housing has an opening OP on one surface, and a lead pin PN1 is fixed to a side surface adjacent to the one surface. The housing includes a metal member 2 arranged to surround the opening, and a lid member 11 that closes the opening and is joined to the metal member. The ends of the metal member and the lid member along the side surface of the main body where the lead pin is arranged are located further inside the main body than the side surface of the main body.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an optical device and an optical transmitter using the same, and more particularly to an optical device having a housing that houses at least an optical waveguide element. [Background technology]

[0002] In the fields of optical communication and optical measurement, optical devices such as optical modulators that use optical waveguide elements having an optical waveguide and a modulation electrode that modulates the light wave propagating through the optical waveguide are widely used. Optical devices have been put to practical use, such as optical waveguide elements, optical components that input and output light waves to and from the optical waveguide elements, and further, as shown in Patent Document 1, driver-integrated modulators that house electronic components such as a driver IC that amplifies a modulated signal input to the optical waveguide element in a single housing.

[0003] Fig. 1 shows a plan view of the optical device, and Fig. 2 shows a cross-sectional view taken along the dashed line A-A' in Fig. 1. As shown in Fig. 1, the housing of the optical device has a main body 1 made of ceramic or a plurality of metals (Kovar, copper tungsten, etc.), and one surface of the main body 1 has an opening OP for mounting components such as an optical waveguide element.

[0004] A metal member 2 (such as Kovar) is disposed on the surface of the main body 1 where the opening OP is located, for fixing a lid for airtight sealing by seam welding or the like. When ceramic is used for the main body 1, it is not possible to directly seam weld the ceramic to the metal lid member, so the metal member 2, such as Kovar, is first joined to the ceramic main body 1 with a brazing material such as AuSn, and then the metal member 2 and lid member 11 are seam welded together. In addition, lead pins (PN1, PN2) are disposed on one or more side surfaces of the housing to electrically connect and relay the inside and outside of the housing.

[0005] FIG. 2 is a cross-sectional view of FIG. 1, particularly showing an optical device hermetically sealed by a lid member 11 and mounted on a printed circuit board 3. Note that the lid member and the printed circuit board are not shown in FIG. 1, and the opening OP in FIG. 1 opens downward in FIG. 2. Inside the housing, components 4 such as a driver IC and optical waveguide elements are arranged and fixed on a pedestal (or housing) 101 provided on a metal housing bottom 10. In an optical device in which a driver IC, an optical waveguide element, and the like are integrated in the same housing, such as a high-bandwidth coherent driver modulator (HB-CDM), the opening OP is arranged facing downward, as shown in FIG. 2. This is to dissipate heat generated by the driver IC from the bottom 10 side, and a heat dissipation mechanism such as a heat sink is arranged on the back side of the bottom 10 (upper side in the drawing). The optical device is mounted so that the cover member 11 that hermetically seals the opening OP of the main body 1 and the printed circuit board 3 come into contact with each other.

[0006] The tips of lead pins (PN1, PN2) fixed to one side of the housing (main body 1) are soldered to a soldering pattern on a printed circuit board 3, electrically connecting the optical device to the printed circuit board. In an optical transmitting device, an optical device is placed on a printed circuit board, and other components are also placed around it, such as signal processing means such as a digital signal processing circuit, and a light source that generates light waves to be input into the optical waveguide element.

[0007] As shown in FIG. 2, when the cover member 11 of the housing is disposed so as to contact the printed circuit board 3, the housing, particularly the cover member 11, is electrically grounded. Therefore, the solder connecting the lead pin PN1 to the printed circuit board may reach the cover member 11 or the metal member 2, potentially causing an electrical short circuit. To avoid this, the distance S0 between the contact point of the lead pin PN1 with the printed circuit board 3 and the side surface of the housing body 1 (the end of the cover member 11) must be sufficiently large, e.g., 1 mm or more. However, the presence of the contact point of the lead pin away from the housing body 1 increases the space required for optical device placement, making it difficult to reduce the component mounting space on the printed circuit board. In particular, in recent years, there has been a demand for the integration of optical devices into ultra-compact transceiver modules, such as QSFP (e.g., QSFP+, QSFP28, QSFP-DD) and SFP (e.g., SFP+, SFP28, SFP-DD). Even a slight reduction in mounting space presents a significant problem. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2021-509483 Summary of the Invention [Problem to be solved by the invention]

[0009] The problem that the present invention aims to solve is to provide an optical device that can be miniaturized, which solves the problems described above, suppresses electrical short circuits between the lead pins arranged on the side of the housing and the cover member, and provides an optical transmission device using the same. [Means for solving the problem]

[0010] In order to solve the above problems, the optical device and optical transmitter of the present invention have the following technical features. (1) An optical device having a housing that houses at least an optical waveguide element, wherein a main body of the housing has an opening on one surface, a lead pin is fixed to a side surface adjacent to the opening, a metal member disposed so as to surround the opening, and a cover member that closes the opening and is joined to the metal member, the lead pin extends along the side surface of the housing toward the lid member and has a tip portion that is bent at the position of the lid member in a direction away from the housing, The end portions of the metal member and the cover member along the side surface of the main body on which the lead pins are arranged are located more inward of the main body than the side surface of the main body.

[0011] (2) In the optical device described in (1) above, the distance from the side surface of the main body to the end of the metal member is 0.5 mm or more.

[0012] (3) In the optical device described in (1) or (2) above, the ends of the metal member and the cover member along the side of the main body part where the lead pins are not arranged are located at the same position as the side of the main body part. (4) In the optical device described in any one of (1) to (3) above, the lead pin has another bent portion that bends in a direction away from the housing midway to the bent tip portion. ( 5 ) (1) above or (4) In the optical device described in 1. above, a notch is provided on the outer side of the main body at the end face of the main body that contacts the metal member.

[0013] ( 6 ) (1) to ( 5 ) The optical device according to any one of the above, characterized in that a protrusion protruding inward from the end face of the main body is formed.

[0014] ( 7 ) In the optical device described in (1) or (2) above, a notch is provided on the inside of the main body at the end face of the main body that contacts the metal member, and the metal member is positioned so as to contact the inner surface of the notch.

[0015] ( 8 ) (1) to ( 7 ) The optical device according to any one of claims 1 to 4, further comprising a driver circuit element disposed adjacent to the optical waveguide element for generating an electrical signal to be applied to a modulation electrode in the optical waveguide element.

[0016] ( 9) the above( 8 and a signal generator for generating a modulation signal to be input to the driver circuit element. [Effects of the Invention]

[0017] The present invention provides an optical device having a housing that houses at least an optical waveguide element, wherein a main body of the housing has an opening on one surface, lead pins fixed to a side surface adjacent to the opening, a metal member arranged to surround the opening, and a lid member that closes the opening and is joined to the metal member, and the ends of the metal member and the lid member along the side surface of the main body on which the lead pins are arranged are located more inward of the main body than the side surface of the main body, thereby ensuring a wider gap between the lead pins and the metal member and the lid member and preventing problems such as electrical short-circuiting of the lead pins to the lid member or the metal member by solder, etc. Furthermore, the amount of protrusion of the lead pins from the side surface of the main body of the housing is reduced, thereby reducing the space occupied by the optical device and contributing to miniaturization. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a plan view of a housing designed for a conventional optical device, viewed from the opening side. [Figure 2] FIG. 2 is a cross-sectional view taken along the dashed line in FIG. 1, showing the optical device arranged on a printed circuit board. [Figure 3] 1 is a cross-sectional view showing a first embodiment of an optical device according to the present invention. [Figure 4] FIG. 4 is a cross-sectional view showing a modified example of a part of FIG. 3. [Figure 5] FIG. 4 is a cross-sectional view showing a second embodiment of the optical device of the present invention. [Figure 6] FIG. 10 is a cross-sectional view showing a third embodiment of the optical device of the present invention. [Figure 7] FIG. 10 is a cross-sectional view showing a fourth embodiment of the optical device of the present invention. [Figure 8] 7 is a diagram illustrating the configuration of a protrusion CN shown in FIG. 6. FIG. [Figure 9] FIG. 10 is a cross-sectional view showing a fifth embodiment of the optical device of the present invention. [Figure 10] 9 is a diagram illustrating the configuration of a protrusion CN shown in FIG. 8. FIG. [Figure 11] FIG. 10 is a cross-sectional view showing a sixth embodiment of the optical device of the present invention. [Figure 12] 1 is a diagram illustrating an optical transmitting device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described in detail below using preferred examples. As shown in Figures 3 to 11, the present invention is an optical device comprising a housing that houses at least an optical waveguide element, wherein a main body 1 of the housing has an opening OP on one side, a lead pin PN1 fixed to a side adjacent to the one side, a metal member 2 arranged to surround the opening, and a lid member 11 that closes the opening and is joined to the metal member, and the ends of the metal member and the lid member along the side of the main body on which the lead pin is arranged are located inside the main body with respect to the side of the main body.

[0020] The housing is made of metals such as SUS304, Kovar, CuW, etc., and the housing body can be formed not only by cutting a single metal material into one piece, but also by combining multiple parts made by cutting, pressing, etc. It is also possible to use ceramic materials for the main body 1 of the housing (meaning at least the trunk part including the side of the housing).

[0021] When a ceramic material is used for the main body 1, the metal member 2 is joined to the main body 1 using a brazing material such as AuSn to enable joining to the metal cover member 11. The metal member 2 and the cover member 11 are joined by seam welding or laser welding to hermetically seal the inside of the housing. 3, similarly to FIG. 2, components to be placed inside the housing, such as optical waveguide elements and driver ICs, are indicated by reference numeral 4, and a portion of the bottom surface 10 of the housing that holds the components 4 is indicated by reference numeral 101.

[0022] A feature of the optical device of the present invention is that, as shown in FIG. 3, the ends of the metal member 2 and the cover member 11 extend into the interior of the housing from the side of the main body 1 of the housing. In FIG. 3, the lead pin PN1 extends parallel to the side of the main body 1, so the distance S1 between the contact point between the lead pin and the printed circuit board and the ends of the metal member 2 and the cover member 11 is the same as the distance from the side of the main body 1 to the ends of the cover member 11, etc. Note that in FIG. 3, the width (length in the left-right direction in the drawing) of the metal member 2 arranged in the portion where the cover member 11 is retracted from the side of the main body 1 is configured to be shorter. However, the present invention is not limited to this. As shown in FIG. 4, the width of the metal member 2 can be set to the same width as the side where it is not retracted (the shaded area on the right side of the drawing), or it can be arranged so that it protrudes into the housing.

[0023] By ensuring that the distance from the side of the main body to the end of the metal member (corresponding to S1 in Figure 3) is 0.5 mm or more, it is possible to effectively prevent electrical short circuits between the lead pins and the cover member 11 (metal member 2) when connecting the lead pins to a printed circuit board with solder or the like.

[0024] 3, the end of the metal member 2 is located inside (closer to the center of the housing) the side surface of the housing main body 1 on which the lead pins are arranged. As a result, a gap is formed below the wall surface of the housing on which the lead pins are arranged, which can prevent solder or the like from coming into contact with the main body 1.

[0025] In the optical device of the present invention, a gap is formed on the side of the metal member 2 (lid member 11) where the lead pin PN1 is arranged, so the cross-sectional shape of the metal member 2 shown in Figure 3 may have different widths on the lead pin side and the opposite side. This state is called an asymmetric state of the metal member.

[0026] As shown in Figure 3, the shape of the lead pin PN1 can be "L-shaped." This allows the distance from the side of the main body 1 of the housing to the tip of the lead pin to be shorter than before, reducing the space required to place the optical device. As a result, the mounting space on the printed circuit board can be expanded. For example, comparing Figures 2 and 3, the mounting space occupied by S0 x "the length of the range in which multiple lead pins are arranged in parallel" can be reduced. Furthermore, the soldering pattern on the printed circuit board can be positioned closer to the housing than before, allowing the component mounting space on the printed circuit board to be expanded.

[0027] Even if the lead pin is not L-shaped but has the conventional shape in which the contact point between the lead pin and the printed circuit board is located outside the side of the housing, as shown in Figure 5, it is only necessary to ensure distance S2 of about 1 mm, so the distance from the side of the housing to the tip of the lead pin can be shorter than before.

[0028] Furthermore, as shown in FIG. 6 or FIG. 9, a notch CU can be provided on the outer side of the main body 1 of the housing at the end face thereof that contacts the metal member 2. This is because the metal member 2 is thin, about 0.5 mm to 1 mm, and the gap S3 formed at the bottom of the wall surface of the housing is often narrow. By using a configuration with a cutout portion CU as shown in Figure 5 or Figure 8, the height of the gap can be made higher, reducing the risk of short-circuit defects due to soldering.

[0029] As shown in FIG. 7 or FIG. 9, it is also possible to form a protrusion CN protruding inward from the end face of the main body 1 to which the metal material 2 is joined. 7, the end of the metal member 2 is located inside (closer to the center of the housing) than the side surface of the main body 1 of the housing on which the lead pins are arranged, and the other side surface of the metal member 2 protrudes inward into the housing. A protrusion CN protruding inward is formed on the inner surface of the side wall of the main body 1 so as to join with this protruding metal member 2. The shape of the protrusion CN may be (a) formed by a protrusion portion 100 of a uniform width, or (b) formed by a stack of protrusion portions 110 of different widths, as shown in FIG. 8 or 10.

[0030] The optical device to which the present invention is applied is very small, for example, approximately 40 mm or less in length, 15 mm or less in width, and 6 mm or less in height. In such a housing, the wall surface of the housing to which the lead pins are fixed is very thin, approximately 1 mm thick. Furthermore, depending on the number and size of components mounted inside the housing, the wall thickness may be even thinner. If the metal member 2 is positioned inside the side of the housing while maintaining the thickness of the housing wall, the bonding area between the main body 1 of the housing and the metal member 2 becomes smaller, which also creates the problem of reduced bonding strength between the components. By providing a protrusion CN inside the housing and increasing the bonding area with the metal member 2, the bonding strength between the components can be improved.

[0031] In Fig. 9, it is possible to obtain both the effect of the notch CU described in Fig. 6 and the effect of the protrusion CN described in Fig. 7. The shape of the protrusion CN provided in Fig. 9 is shown in Fig. 10.

[0032] In addition, as a method of increasing the bonding strength between the main body 1 of the housing and the metal member 2, as shown in Figure 11, a notch (CU2) is provided on the inside of the main body 1 at the end face of the main body 1 that contacts the metal member 2, and the metal member 2 is positioned so that it contacts the inner surface of the notch. 9, the left and right cross sections of the metal member 2 are the same, but it is also possible to make them asymmetrical. For example, the width or thickness of the metal member 2 may be different on the left and right sides, or a notch CU2 may be provided only on the side where the lead pins are arranged, while the other side remains conventional.

[0033] By using the configuration shown in Figure 11, the main body 1 of the housing and the metal member 2 can be joined on two surfaces, and the joining area between the parts, i.e., the joining strength, can be increased without providing a protrusion CN inside the housing as shown in Figure 7. The structure of the housing is also simplified, which reduces the manufacturing cost of the housing.

[0034] 12 is a diagram showing an example of an optical transmission device, and the housing structure of the optical device, which is a feature of the present invention, can be applied to the housing CS in FIG. In the optical device, a driver circuit element DRV is disposed adjacent to an optical waveguide element OE, and generates an electrical signal Sout to be applied to a modulation electrode of the optical waveguide element. The optical waveguide element OE and the driver circuit element DRV are housed in the same housing CS. Input light Lin is input to an optical waveguide OW formed in the optical waveguide element OE using an optical fiber FB via an optical component such as a lens. On the other hand, light waves output from the optical waveguide element OE are combined, for example, via a polarization combining means PC, and input to another optical fiber via an optical component such as a lens to become output light Lout.

[0035] Furthermore, it is possible to provide a signal generator DSP (digital signal processing device) that generates a modulated signal Sin to be input to the driver circuit element DRV, and configure it as an optical transmitter. The housing CS and the signal generator DSP can also be incorporated into a single chassis. [Industrial Applicability]

[0036] As described above, according to the present invention, it is possible to provide an optical device that can be miniaturized by suppressing electrical short circuits between the lead pins arranged on the side of the housing and the cover member, and an optical transmission device using the same. [Explanation of symbols]

[0037] 1. Main body of the housing 2 Metallic parts 3 Printed circuit board 4 Components (optical waveguide elements, driver ICs, etc.) 10 Bottom of the housing 11 Housing cover member PN1, PN2 lead pins CU,CU2 notch CN protrusion

Claims

1. An optical device having a housing that accommodates at least an optical waveguide element, The main body of the housing has an opening on one side, and lead pins are fixed to a side surface adjacent to the opening. a metal member disposed so as to surround the opening; a cover member that closes the opening and is joined to the metal member, the lead pin extends along the side surface of the housing toward the lid member and has a tip portion that is bent at the position of the lid member in a direction away from the housing, An optical device, characterized in that the ends of the metal member and the cover member along the side surface of the main body on which the lead pins are arranged are located more inward than the side surface of the main body.

2. 2. The optical device according to claim 1, wherein the distance from the side surface of the main body to the end of the metal member is 0.5 mm or more.

3. An optical device as described in claim 1 or 2, characterized in that the ends of the metal member and the cover member along the side of the main body portion on which the lead pin is not arranged are positioned at the same position as the side of the main body portion.

4. An optical device as described in any one of claims 1 to 3, characterized in that the lead pin has another bent portion that bends in a direction away from the housing halfway up to the bent tip portion.

5. 5. The optical device according to claim 1, wherein a notch is provided on the outer side of the main body at an end face of the main body that contacts the metal member.

6. 6. The optical device according to claim 1, wherein a protrusion is formed on an end face of said main body portion so as to protrude inward of said main body portion.

7. 3. The optical device according to claim 1, wherein a notch is provided on the inside of the main body at the end face of the main body that contacts the metal member, and the metal member is positioned so as to contact the inner surface of the notch.

8. 8. The optical device according to claim 1, further comprising a driver circuit element disposed adjacent to said optical waveguide element for generating an electrical signal to be applied to a modulation electrode in said optical waveguide element.

9. 9. An optical transmitter comprising: the optical device according to claim 8; and a signal generator for generating a modulated signal to be input to the driver circuit element.

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