JP2011044454A - Optical transmission module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic package type optical transmission module for mounting a monitor PD in a form not affecting a high-frequency electric signal. <P>SOLUTION: In the optical transmission module 1, a package frame 12 made of ceramic for surrounding sides of an LD 11 is provided on a bottom ceramic substrate 11 for mounting an LD 3, the LD 3 and a PD 4 for monitoring are sealed into a package 2 where a lid 14 having an optical window is mounted onto the package frame, and light from a front end face 3a of the LD3 having a light axis in parallel with the bottom ceramic substrate 11 is reflected by a reflecting member and is emitted from the optical window. The package frame 2 includes a signal supply substrate 15 where a signal line 15b to the LD 3 is formed at a rear part of the LD 3, and a mount section 16 of the PD 4 physically separated from the signal line 15 and projecting in the direction of the LD 3 at an upper portion of the signal supply substrate 15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a ceramic package type optical transmission module used for optical communication.

  An optical transmission module used for optical communication uses light from a laser diode (LD) as signal light, and there are the following types. For example, there is a CAN package type in which an optical window is provided at a front end portion of a cylindrical metal package that accommodates an LD and lead pins extend from the rear end portion (see, for example, Patent Document 1). In addition, there is a butterfly package type in which an optical window is provided at the front end portion of the rectangular parallelepiped package and lead pins extend from the side portion and / or the rear end portion. For example, see Patent Document 2).

JP-A-5-102617 JP-A-6-318863

  At present, in addition to the above, a smaller and cheaper ceramic package type optical transmission module is considered. FIG. 3 is a perspective view for explaining a ceramic package type optical transmission module, in which the optical transmission module is shown with a cover with an optical window omitted. In the illustrated ceramic package type optical transmission module 100, a package 102 that houses an LD 101 is configured as follows. That is, the package 102 is made of a ceramic that surrounds the side of the electronic cooler 103 on the bottom ceramic substrate 111 on which electronic parts such as the electronic cooler 103 are mounted and a connection portion with an external electric circuit is provided. A package frame 112 is attached, a metal frame 113 is provided thereon, and a metal lid with an optical window (not shown) is attached. The ceramic package shown in the drawing is a stacked package in which the package frame 112 is formed by sequentially stacking rectangular annular ceramic substrates.

In this optical transmission module 100, the LD 101 is mounted so that its optical axis is parallel to the bottom ceramic substrate 111 due to the limitation of mounting space. Then, light from the front end surface 101a of the LD 101 is reflected in a direction perpendicular to the bottom ceramic substrate 111 (X direction in the drawing) by a reflecting member (not shown) and output as signal light to the outside of the package 102 through the optical window. I try to let them.
In the optical transmission module 100, a high-frequency line 114 that supplies an electrical signal to the LD 101 is formed on the signal supply substrate 115 in the rear portion of the LD 101 in the package frame 112.

  Also, in the ceramic package type optical transmission module 100, as in the conventional optical transmission module, monitoring of the light output intensity of the LD 101 is indispensable. Therefore, for monitoring so that light from the rear end face 101b of the LD 101 can be received. The photodiode (PD) is mounted in the package 102. However, depending on the mounting form of the monitor PD, there is a problem that the high-frequency electric signal is affected.

  An object of the present invention is to provide a ceramic package type optical transmission module in which a monitor PD is mounted in a form that does not affect a high-frequency electric signal in view of the above situation.

  In order to solve the above-described problems, the optical transmission module of the present invention is provided with a ceramic package frame that surrounds the side of the laser diode on the bottom ceramic substrate on which the laser diode is mounted, and on which an optical window is provided. A laser diode and a light-receiving element for monitoring are sealed in a package having a lid attached thereto, and light from the front end face of the laser diode having an optical axis parallel to the bottom ceramic substrate is reflected by a reflecting member. The package frame has a signal supply board in which a signal line for the laser diode is formed in a rear part of the laser diode, and the signal line and the physical line are disposed above the signal supply board. And a light receiving element mounting portion that protrudes in the direction of the laser diode.

  It is preferable that the mounting surface of the mounting portion is directed toward the lid and is inclined with respect to the optical axis of the laser diode. The package frame can be formed by sequentially stacking rectangular annular substrates.

  According to the ceramic package type optical transmission module of the present invention, since the monitor PD mounting portion that does not touch the high-frequency line is provided integrally with the package, the high-frequency electric signal supplied from the outside is not delayed in the LD. Can be supplied. Further, since the monitor PD mounting portion is provided so as to protrude in the LD direction, a sufficient monitor current can be secured in the monitor PD.

It is a figure explaining an example of the optical transmission module of this invention. It is a figure explaining an example of the optical transmission module of this invention. It is a figure explaining the conventional optical transmission module.

Hereinafter, the outline of the optical transmission module of the present invention will be described with reference to FIG. 1A is a perspective view thereof, and FIG. 1B is a perspective view of a state before a lid described later is attached.
As illustrated by reference numeral 1 in FIG. 1A, an optical transmission module of the present invention (hereinafter referred to as an optical module) is provided with a ceramic package frame 12 on a bottom ceramic substrate 11, and a metal frame thereon. 13 and a package 2 to which a lid 14 with an optical window such as a flat glass 14a is attached. The size (width × depth × height) of the package 2 is, for example, 5.6 × 5.6 × 3.0 mm. As shown in FIG. 1B, the optical transmission module 1 is formed by hermetically sealing an LD 3 and a monitor PD 4 in the package 2.

  For example, an element such as an electronic cooler 5 is mounted on the bottom ceramic substrate 11 of the package 2. The package frame 12 constitutes a side wall surrounding the side portion of the element. For example, the package frame 12 is formed by sequentially laminating ceramic rectangular annular substrates on which wiring patterns and the like are formed. The annular substrate is produced by processing a ceramic sheet. The package frame 12 integrally has a signal supply board 15 on which a wiring pattern 15a such as a high-frequency line 15b is formed and a monitor PD mounting portion 16 on which the monitor PD4 is mounted in a portion corresponding to the rear of the LD3.

  The monitor PD mounting portion 16 is formed above the signal supply substrate 15 so as to protrude in the direction of the LD 3 in a form physically separated from the wiring pattern 15a. A monitor PD mounting pattern 16a and a wiring pattern 16b constituting a wiring for the monitor PD 4 are formed on an inclined mounting surface 16c, which will be described later, of the monitor PD mounting portion 16. As will be described later, the present optical transmission module 1 is characterized in that the monitor PD mounting unit 16 is integrally provided on a package frame 12 constituting a package.

  The lid 14 is attached to the package frame 12 via the metal frame 13 so as to hermetically seal the LD 3 and the monitor PD 4. A lid 14 c is formed on a metal flat plate 14 c having an opening 14 b for passing signal light in the center. An optical member 14a such as a lens or flat glass is fixed so as to close the opening 14b. The optical member 14a serves as an optical window that transmits the signal light from the LD 3, and a low-melting glass or the like is used for fixing the optical member 14a so as not to impair the hermeticity of the package.

  The LD 3 is mounted so that its optical axis is parallel to the bottom ceramic substrate 11. In this example, the LD 3 is mounted on the electronic cooler 5 mounted on the bottom ceramic substrate 11 via the submount 6. Mounting on the submount 6 is performed using, for example, Ag paste. The light from the front end surface 3a of the LD 3 is reflected in a direction perpendicular to the bottom ceramic substrate 11 (X direction in the drawing) by a reflecting member (not shown), and is output as signal light to the outside of the package 2 through the optical member 14a. Is done.

The monitor PD 4 is mounted on the monitor PD mounting pattern 16a using Ag paste or the like so that light from the rear end surface 3b of the LD 3 can be received.
Although illustration is omitted, an electrode pad is formed on the lower end surface of the bottom ceramic substrate 11, and the electrode pad, the high frequency line 15 b, the wiring pattern 16 b, and the like are attached to the bottom ceramic substrate 11 and the package frame 12. Electrical connection is made through a provided through hole or the like. In the optical transmission module 1, when these electrode pads and an external circuit board are electrically connected using a flexible printed circuit board or the like, a high-frequency electrical signal can be supplied to the LD 3 or an electrical signal from the monitor PD 4 can be taken out. it can.

Then, the characteristic part of the optical transmission module 1 is demonstrated using FIG. FIG. 2 is an enlarged cross-sectional view of a main part of the optical transmission module of FIG.
In the optical transmission module 1, as shown in FIG. 2, in the package frame 12 of the package 2, the first annular substrate 12a on which the signal supply substrate 15 (the high frequency line 15b (see FIG. 1)) is formed, and the monitor PD mounting A third annular substrate 12c is interposed as a spacer between the second annular substrate 12b on which the portion 16 is formed.

  Therefore, as shown by the phantom lines in FIG. 3, the submount 105 for the monitor PD 104 made of an insulating substrate such as an alumina substrate does not directly contact the high frequency line 114. The high frequency electrical signal supplied from the outside can be supplied to the LD 3 without deteriorating.

In addition, since the monitor PD mounting portion 16 is integrally formed with the package 2, the number of mounting processes is small and easy as compared with the case where the monitor PD 4 is mounted via the submount.
Furthermore, the monitor PD mounting portion 16 is provided so as to protrude in the direction of LD3, and since the distance between the monitor PD4 and the rear end surface 3b of the LD3 is short, a sufficient monitor current can be secured in the monitor PD4.

Further, the mounting surface 16c of the monitor PD mounting portion 16 is an inclined surface with respect to the optical axis of the LD3. With this configuration, not only when the monitor PD4 is mounted in the form offset from the optical axis of the LD3 as shown in the figure, but also when the monitor PD4 is mounted on the optical axis of the LD3, the reflected light from the monitor PD4 is applied to the LD3. You can prevent it from returning.
More specifically, the mounting surface 16c of the monitor PD mounting portion 16 is an inclined surface facing the direction of the lid 14 (upward direction). By using such an inclined surface, it is possible to easily mount the monitor PD4 from above using an existing mounting apparatus and wire bonding between the surface electrode of the monitor PD4 and the wiring pattern 16b.

  In the above example, the monitor PD 4 has electrodes on both the front surface and the back surface, and the wiring pattern 16 b that is electrically connected to the front surface electrode is provided in the monitor PD mounting portion 16. The wiring pattern to be connected may be provided in another part such as the signal supply board 15. Further, when the monitor PD has electrodes (anode, cathode) only on the upper surface, the monitor PD mounting pattern 16a is not necessarily formed of a conductive metal, and further, a signal supply is provided for the wiring pattern for each electrode. You may provide in another parts, such as the board | substrate 15.

In the above example, the package frame 12 is formed by sequentially laminating annular substrates formed by processing ceramic green sheets to form a multilayer structure. However, the package frame 12 is manufactured by placing a ceramic material in a mold for firing. You can also. However, it is cheaper to produce from a ceramic green sheet.
Further, the metal frame 13 is not an essential constituent element, and the metal lid 3 may be simply attached directly to the upper part of the ceramic package frame 12. As long as the lid 14 is attached so as to seal the space formed by the package frame 12 and the bottom ceramic substrate 11, the attachment structure of the lid 14 may be in any form.

DESCRIPTION OF SYMBOLS 1 ... Optical transmission module, 2 ... Package, 3 ... LD, 4 ... Monitor PD, 5 ... Electronic cooler, 6 ... Submount, 11 ... Bottom ceramic substrate, 12 ... Package frame, 13 ... Metal frame, 14 ... Cover, 15 ... Signal supply board, 16 ... Monitor PD mounting part.

Claims (3)

A ceramic package frame surrounding a side of the laser diode is provided on a bottom ceramic substrate on which the laser diode is mounted, and a laser-attached lid is attached on the ceramic frame. A light transmission module that seals a light receiving element for monitoring and reflects light from a front end face of the laser diode having an optical axis parallel to the bottom ceramic substrate by a reflecting member and emits the light from the optical window,
The package frame has a signal supply board in which a signal line for the laser diode is formed at a rear portion of the laser diode, and is physically separated from the signal line above the signal supply board. And an optical transmitter module having a mounting portion of the light receiving element protruding in the direction of the laser diode.   2. The optical transmission module according to claim 1, wherein a mounting surface of the mounting portion is directed toward the lid and is inclined with respect to an optical axis of the laser diode.   The optical transmission module according to claim 1, wherein the package frame is formed by sequentially stacking rectangular annular substrates.

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