JP2973670B2 - Optical semiconductor photodetector with built-in preamplifier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor device for a high band, and more particularly to an optical semiconductor light receiving device having a built-in preamplifier.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a higher optical bit rate in trunk line optical communication, and transmission / reception elements capable of high speed have been developed. When these elements are modularized, the performance of the light receiving element module is greatly affected by the mounting method of the light receiving element and the amplifier and the connection method between the elements.

In a conventional light receiving element module, only a light receiving element is mounted on a can-type stem, and a preamplification is performed by a DIP type case as represented by a coaxial type light receiving module or a PINFET module which is fiber-coupled by a lens or the like. Some are mounted inside. In this module structure with a built-in preamplifier, the light receiving element mounting substrate and the preamplifier mounting substrate are separate, and the light receiving element is mounted on the element mounting substrate on which the electrode pattern for electrical connection is formed. The preamplifier element is mounted on another mounting substrate on which the element mounting electrode pattern is formed,
Inside the IP type case, the light receiving element mounting substrate faces the light receiving surface toward the fiber end face, and the preamplifier mounting substrate is mounted on the bottom surface inside the case on the rear side of the light receiving element mounting substrate or another substrate by soldering or the like. ing. The light receiving element and the preamplifier are connected to each other by metal wires via respective electrode patterns.

[0004]

In the above-described conventional light receiving device with a built-in preamplifier, the light receiving element surface and the preamplifier mounting surface are mounted vertically so that the light receiving element and the preamplifier mounting surface are mounted vertically. The electrical connection with the amplifying element cannot be directly connected with the result wire, but via an electrode pattern formed on each mounting substrate. Therefore, there has been a problem that the connection distance becomes long, the inductance of the electric connection becomes large, and there is a restriction in a high frequency band. For example,
The thickness usually used between the light receiving element and the preamplifier is about 3
When a connection wire of 0 μmφ is used, in the case of the conventional structure, the connection distance is 5 mm or more, and the inductance of the wire itself is 5 nH or more. Therefore 2-3GHz
The bandwidth is limited to a certain extent. Further, since the connection distance between the light receiving element and the preamplifier is long, the reflection frequency band due to impedance mismatch between the elements becomes low, and the signal band is limited.

Further, the hermetic sealing of the element in the conventional structure is a method of taking the whole case, and hermetically sealing the fiber pigtail portion with solder or the like, and then sealing the cap with a seam welder. In this case, since the hermetic sealing test is performed after the module is assembled, there is also a problem that a fine leak test cannot be performed due to the resin of the fiber coating and the number of assembly steps and reliability are lacking.

[0006]

According to the present invention, there is provided an optical semiconductor light receiving device with a built-in preamplifier, comprising: a carrier on which a light receiving element and a preamplifier IC for amplifying an output electric signal of the light receiving element are mounted; An optical semiconductor light receiving device device having a coupling lens fixed to the optical fiber and a light input optical fiber having a ferrule incorporated in a box-shaped case, wherein the light receiving element and the preamplifier IC are provided on the carrier. The carrier is mounted so that the light receiving surface of the element and the mounting surface of the preamplifier IC are parallel to each other, and the carrier is mounted on the light receiving element.
The light receiving surface and the mounting surface of the preamplifier IC are
Perpendicular to the plane parallel to the light emission direction from the optical fiber
It is characterized in that it is placed in the box-shaped case so as to be straight and light from the optical input optical fiber is incident on the light receiving element.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. 1A and 1B are cross-sectional views of the top and side surfaces of an optical semiconductor photodetector device with a built-in preamplifier according to an embodiment of the present invention.
2A, 2B, and 2C are a front view, a side sectional view, and a bottom view of an element storage carrier that is a main part of the present invention.

The element storage carrier 1 has a concave shape on the fiber end face side, and the element mounting surface is a metal conductor 19.
Around this, a lead electrode pattern 21 is formed at a position that is the same as or slightly higher than the element mounting surface, and an insulator 20 connected and wired to each of the lead terminals 13 on the bottom surface is soldered. Further, a mounting plate 12 having a thickness of several mm is soldered to the bottom surface so that the lead terminals 13 are not short-circuited when the element storage carrier 1 is fixed. The lead electrode pattern for connecting the output of the preamplifier has a strip line and an impedance of 50Ω.

The light receiving element 15 and the preamplifier IC 14 previously mounted on the elements 16 and 17 on the element mounting surface of the element storage carrier 1 with, for example, AuSn solder or the like are fixed with, for example, AuSn solder and electrically connected with bonding wires. After making the connection, the glass cap 11 metallized in a nitrogen atmosphere is
Hermetically sealed with Sn solder. In the state of the element storage carrier 1 on which the elements are mounted as described above, BT selection is performed, and the surface of the mounting plate 12 is fixed to the mounting substrate 5 with PbSn solder.

The optical coupling between the fiber and the light receiving element is performed in advance by using a rod lens 2 such as a SELFOC lens (trade name).
The fiber ferrule 4 is fitted to a lens holder 3 in which the fiber ferrule 4 is fixed by AuSn solder, and is fixed by soldering or YAG laser welding. The mount substrate 5 on which the element storage carrier is fixed and the lens holder 3 in which the fiber ferrule 4 is fixed in position. It is fixed by YAG laser welding via a slide ring 6. At this time, the optical axis is adjusted in the X, Y, and Z axis directions so that the output current is maximized while light is incident from the end of the fiber and the output current of the light receiving element is monitored.

The optical system assembled as described above via the mounting substrate 5 is fixed to the bottom surface of the case 7 having the external lead terminals 10 with solder having a lower melting point than the solder used when fixing the element storage carrier, for example, InSn solder. The lead terminal 13 of the element storage carrier and the case lead terminal 10 are connected by soldering or YAG laser welding, and the low melting point solder 9 is attached to the case.
And a metal cap 8 is sealed with a seam welder or the like, whereby a light receiving element device can be obtained.

In this embodiment, a ternary AP is used for the light receiving element.
D. As a result of using Si-IC as the preamplifier IC, the wavelength 1.
The minimum receiving sensitivity is -34d at 2.488 Gbps of 3 μm.
An optical semiconductor light receiving device with a built-in preamplifier having a Bm (bit error rate of 10 ⁻¹¹ hour) was obtained.

FIGS. 3 and 4 show a second embodiment of the present invention. FIG. 3 is a bottom view of the element storage carrier, and FIG. 4 is an assembly view in which the element storage carrier is fixed to a mount substrate for fiber coupling assembly.

The mounting plate 22 brazed to the bottom surface of the element storage carrier is fixed to the mounting substrate 5 which has a shape projecting outside the outer shape of the bottom surface of the element storage carrier in the direction of the incident optical axis. First, similarly to the first embodiment, the YAG laser welded portion 23 can be temporarily fixed by soldering or the like, and then the YAG laser welded portion 23 can be permanently fixed from the upper surface direction by YAG laser welding. Therefore, in the present embodiment, YAG laser welding can be employed for fixing the element storage carrier, so that there is an advantage that the long-term reliability of the fixing portion is improved and the melting point of the solder to be used later is raised.

[0015]

As described above, according to the present invention, by mounting the bare chip of the light receiving element and the preamplifier close to the same surface, the stray capacitance of the element can be reduced, and the output of the light receiving element and the output power of the light receiving element can be reduced. As a result of connecting the input of the preamplifier to the input, the length of the wire becomes shorter, the inductance which is a problem in the high frequency band can be reduced, and the reflection frequency band for impedance mismatch between the elements can be increased. Can be In addition, the use of the package output terminal matched to the output impedance of the preamplifier of 50Ω facilitates impedance matching with the externally connected amplifier. Furthermore, the use of the hermetically sealed element storage carrier has an effect that it is easy to handle at the time of assembling in modularization and has excellent reliability.

[Brief description of the drawings]

FIG. 1 is a mounting diagram of an optical semiconductor photodetector device with a built-in preamplifier of the present invention.

FIG. 2 is an element mounting view of the element storage carrier shown in FIG.

FIG. 3 is a diagram of an element storage carrier according to a second embodiment.

FIG. 4 is a fixed mounting diagram of the element storage carrier and the mounting substrate according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Element storage carrier 2 Lens 3 Lens holder 4 Fiber ferrule 5 Mounting board 6 Slide ring 7 Case 8 Cap 9 Solder 10 External lead terminal 11 Glass cap 12, 22 Mounting plate 13 Lead terminal 14 Preamplifier IC 15 Light receiving element 16 , 17 Capacitor 19 Element mounting heat block 21 Lead pattern

Claims (2)

(57) [Claims] A carrier on which a light receiving element and a pre-amplification IC for amplifying an output electric signal of the light receiving element are mounted, and a light input optical fiber having a coupling lens and a ferrule fixed to a lens holder are provided. An optical semiconductor light-receiving element device incorporated in a mold case, wherein the light-receiving element and the preamplification IC are arranged such that a light-receiving surface of the light-receiving element and a mounting surface of the preamplification IC are parallel on the carrier. And the carrier is mounted on the light receiving surface of the light receiving element.
And the mounting surface of the preamplifier IC is the optical input optical fiber.
Perpendicular to the plane parallel to the light
An optical semiconductor light receiving device with a built-in preamplifier, wherein the light receiving device is mounted in the box-shaped case so that light from the optical input optical fiber is incident on the light receiving device. 2. A box-shaped case having a plurality of external connection lead terminals on a bottom surface of a light receiving element storage carrier having a light receiving element mounted thereon and an optical fiber for input light having a coupling lens and a ferrule fixed to a lens holder. An optical semiconductor light-receiving device device having a built-in box-shaped case and an upper surface thereof sealed by a cap, wherein the light-receiving device housing carrier includes a first surface provided with a plurality of lead terminals, and the plurality of lead terminals. A second surface perpendicular to the first surface on which a plurality of lead patterns electrically connected to each other are provided, and the light receiving element and the output electricity of the light receiving element are provided on the second surface. The preamplification IC for amplifying a signal is the light receiving surface of the light receiving element and the mounting surface of the preamplification IC is the second
The light receiving element, the preamplifier IC and the plurality of lead patterns are respectively connected by bonding wires, and the second surface is sealed with a glass cap, An optical semiconductor photodetector device with a built-in preamplifier, wherein the plurality of lead terminals are housed in the box-shaped case so as to be electrically connected to the plurality of external connection lead terminals of the box-shaped case. .