JPH1187852A - Semiconductor laser module with electronic cooler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a decrease in an optical frequency response level in an available band of a public communication by changing inductance of a ground line between a module package and a chip mount carrier, thereby shifting a resonance frequency of a semiconductor laser module. SOLUTION: A ground line is formed by electrically connecting in series a conductive first connecting means 11 having a large sectional area overhanging to the vicinity of a chip mount carrier 3 from an inner bottom 100 of a module package 1 between the package 1 and the carrier 3 to a short conductive second connecting means 94 having a small sectional area for connecting the means 11 to the carrier 3. Thus, a resonance frequency of a semiconductor module is shifted to a high frequency band without lowering a heat exchange efficiency of a Peltier element, and a modulation limit is improved. Accordingly, deterioration of the modulation characteristics of the module can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser module with an electronic cooler, and more particularly to a semiconductor laser module of a direct modulation system for directly modulating a high-frequency input signal into an optical signal.

[0002]

2. Description of the Related Art In recent years, semiconductor laser modules have been
Applications to communication fields that handle high-speed modulated signals such as microwave / quasi-microwave frequency signals such as TV and public communication, and gigabit high-speed digital signals have been actively attempted, and practical applications have begun. In short- and medium-distance transmissions of hundreds of meters to several kilometers with little signal distortion accumulation, a direct intensity modulation method for converting a high-frequency signal into an optical signal as a direct modulation signal is suitable. The oscillation characteristics of the semiconductor laser of such a semiconductor laser module have a very large temperature dependence, and a shift in the threshold current density or the oscillation wavelength occurs due to a temperature change. It is essential to keep the temperature constant, and the temperature of the laser diode is controlled using a cooling element such as a Peltier element electronic cooler.

[0003]

In a conventional semiconductor laser module, an electronic cooler, a ground line, and the like constituting the module form a resonance circuit. For example, as shown in FIG. In some cases, the above-described circuit resonates in a frequency band centered at the center, and the optical frequency response level decreases.
For this reason, in public communication that often uses a frequency close to the above-mentioned frequency band such as the 1.5 GHz band or 1.9 GHz band as a channel band, and in high-speed digital communication that uses a transmission rate close to the above-mentioned frequency band, In such a semiconductor laser module, it has been difficult to secure a sufficient modulation signal.

Accordingly, an object of the present invention is to provide a semiconductor laser module with an electronic cooler in which the resonance frequency of a semiconductor laser module is shifted to prevent a decrease in an optical frequency response level in a band used for public communication.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies, and as a result, changed the inductance of the ground line between the module package and the chip mounting carrier, thereby changing the resonance circuit including the ground line. The present inventors have found that the above-mentioned object can be achieved by shifting the resonance frequency of the signal from the frequency band of public communication used in the modulated signal transmission means, and completed the present invention.

That is, the present invention provides a semiconductor laser diode, a conductive chip mounting carrier on which the semiconductor laser diode is mounted, and an electronic cooler mounted with the chip mounting carrier and absorbing heat from the chip mounting carrier. A conductive module package in which the electronic cooler is mounted on the inner bottom thereof and the heat absorbed by the electronic cooler is released, and a modulation signal for transmitting an input modulation signal of a predetermined frequency to the semiconductor laser diode. A transmission means, a semiconductor laser module with an electronic cooler having at least a ground line for electrically connecting the module package and the chip-mounted carrier, by changing the inductance of the ground line,
A semiconductor laser module with an electronic cooler, wherein a resonance frequency of a resonance circuit including the ground line is shifted so as to be out of a predetermined frequency band used in the modulation signal transmission means. In the resonance circuit generated in the semiconductor laser module with the electronic cooler, the resonance frequency of the resonance circuit can be changed by changing the inductance of the ground line that electrically connects the module package and the chip mounting carrier. Thereby, the resonance frequency can be shifted to a high band or a low band so as to deviate from the frequency band of the public communication used in the semiconductor laser module, and it is possible to prevent a decrease in the optical frequency response level in the band used for the public communication. .

The present invention also provides a conductive first connecting means having a large cross-sectional area, wherein the ground line projects from the inner bottom of the module package to the vicinity of the chip mounting carrier, the first connecting means and the chip. A conductive second connecting means having a small cross-sectional area for connecting to a mounting carrier, reducing an inductance of the ground line, and changing a resonance frequency of a resonance circuit including the ground line to the modulation signal. A semiconductor laser module with an electronic cooler characterized by shifting to a higher frequency range than a predetermined frequency band used in the transmission means. A conductive first connection means having a large cross-sectional area, wherein the ground line extends from the inner bottom of the module package directly to the vicinity of the chip mounting carrier;
By forming the conductive means from the conductive second connecting means having a small cross-sectional area for connecting the connecting means and the chip mounting carrier, the parasitic inductance generated in the ground line can be reduced due to the large cross-sectional area of the first connecting means. In addition, since the first connecting means extends to the vicinity of the chip-mounted carrier, the distance between the first connecting means and the chip-mounted carrier is shortened, and the second connecting means is long even if the cross-sectional area is small. In this case, the parasitic inductance generated in the ground circuit is reduced, the parasitic inductance generated in the entire ground line is reduced, and the resonance frequency of the resonance circuit including the ground line is reduced to a predetermined value used in the modulation signal transmission means. It is possible to shift to a higher frequency band so as to deviate from the frequency band. On the other hand, since the cross-sectional area of the second connecting means is small, it is also possible to suppress the return of heat transmitted from the module package to the chip mounting carrier through the first connecting means. Therefore, by adopting the ground line structure including the first connection means and the second connection means, it is possible to prevent the return of heat from the module package to the chip mounting carrier and reduce the parasitic inductance generated in the ground line, It is possible to shift the resonance frequency of the resonance circuit of the semiconductor laser module to a high frequency so as to be out of the predetermined frequency band used by the modulation signal transmission means. In particular, by forming the first connection means on the inner bottom portion of the conductive module package directly connected to the externally provided ground plane, for example, as compared with the case where the first connection means is formed on the side wall or the like of the module package, The generation of unnecessary parasitic components on the ground line can be prevented, and the high-frequency shift of the resonance frequency can be performed with good reproducibility.

It is preferable that the first connection means is formed integrally with the inner bottom of the module package. As described above, by integrally molding the first connection means with the inner bottom of the module package, the reliability of the semiconductor laser module with the electronic cooler is improved, and the number of mounting steps of the first connection means is reduced, thereby reducing the manufacturing process. Simplification is possible.

[0009] The first connection means is such that a part of the inner bottom of the module package protrudes to a height near the upper surface of the chip mounting carrier, and has a connection bottom for connecting the second connection means on the upper surface. It may be.
By adopting such a structure of the first connection means, it is possible to improve the durability against impacts and the like.

[0010] It is preferable that the first connecting means is a plate-shaped metal block fixed to the module package by a fixing means detachable. In the manufacturing process of the semiconductor module, it is necessary to position a Peltier element electronic cooler, a chip-mounted carrier, a condensing lens, and other members that require optical axis adjustment. The first connection means can be attached after fixing each of the above-mentioned members in a predetermined place by being fixed by the fixing means, and a work space at the time of the above-mentioned alignment can be secured.

The plate-shaped metal block is made of nickel,
It is preferable to use an alloy mainly composed of iron or cobalt or an alloy mainly composed of copper or tungsten. By forming the plate-shaped metal block from an alloy mainly composed of nickel, iron and cobalt, a semiconductor laser module can be manufactured at low cost. It is possible to improve the electric conductivity and the strength of the block.

The present invention also provides a conductive second connecting means having a small cross-sectional area for connecting the module package and the chip mounting carrier, wherein the ground line connects the module package and the chip mounting carrier.
Alternatively, the semiconductor device comprises: third connection means having a predetermined inductance value provided on the module package; and conductive second connection means having a small cross-sectional area for connecting the third connection means and the chip mounting carrier. Increasing the inductance of the ground line to shift the resonance frequency of the resonance circuit including the ground line to a lower frequency band than a predetermined frequency band used in the modulation signal transmission means. Semiconductor laser module with an electronic cooler. As described above, by increasing the inductance of the ground line, it is possible to shift the resonance frequency of the resonance circuit to a lower frequency band outside the frequency band of public communication used in the semiconductor laser module. It is possible to prevent a decrease in the optical frequency response level in the used band. On the other hand, since the cross-sectional area of the second connecting means constituting the ground line is small, it is also possible to suppress the return of heat transmitted from the module package to the chip mounting carrier.

It is preferable that the inductance of the ground line is 10 nH or more. Since the ground line has an inductance of 10 nH or more, the resonance frequency is shifted to a low frequency so as to deviate from the frequency band of the public communication used in the semiconductor laser module. It is possible to effectively prevent the decrease.

It is preferable that the third connection means is composed of one or more selected from the group consisting of a coil, an inductance chip, a lead line, a wire, and a metal transmission line. By using these, the inductance of the first connection means can be easily increased.

It is preferable that the second connection means is formed of a bonding wire or a ribbon wire. By forming the second connection means from a bonding wire or a ribbon wire, a ground line having a small cross-sectional area can be easily formed, and heat is prevented from flowing back from the module package to the chip mounting carrier passing through the ground line. It is possible to do.

The electronic cooler is in contact with the chip-mounted carrier and the module package, respectively, and is made of any of alumina (Al ₂ O ₃ ), aluminum nitride (AlN) and calcium titanate (CaTiO ₃ ) as a main material. It is preferable to include a dielectric substrate made of a ceramic material and a Peltier effect element sandwiched between the dielectric substrates. By using alumina or the like for the dielectric substrate of the electronic cooler, it is possible to improve the heat absorption / radiation efficiency by improving the heat conduction characteristics in addition to the improvement of the strength, and it is possible to secure the stable operation of the semiconductor laser module.

[0017] It is preferable that the modulating signal transmitting means comprises a metal transmission line formed on a ceramic insert penetrating the module package, or a coaxial connector fixed to the module package.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 13 shows an example of a semiconductor laser module using a conventional Peltier element electronic cooler. In the figure, 1 is a butterfly type module package, 2 is a semiconductor laser diode, 3 is a chip mounting carrier, 4 is a Peltier element electronic cooler, 5 is an electrode pad, 6 is a ceramic insert, and 7 is patterned into a ceramic insert. Reference numeral 8 denotes a lead pin serving as a modulation signal input terminal, reference numerals 91, 92, and 93 denote bonding wires, and reference numeral 10 denotes a via hole for connecting the metallized transmission line to a module package. The Peltier device electronic cooler 4 includes a first dielectric plate substrate 41 and a second dielectric plate substrate 41.
And a Peltier effect element 43 using a pn junction sandwiched between the dielectric plate substrates 42.

In the conventional semiconductor laser module shown in FIG. 13, first, a DC drive current is input through a lead pin to excite and oscillate the semiconductor laser diode 2, and then an analog high-frequency or high-speed digital modulation signal is input from the lead pin. Semiconductor laser diode 2
Is directly modulated. Although omitted in the figure, an output signal from the semiconductor laser diode is guided outside the module package by an optical fiber. When continuous excitation oscillation is maintained, the loss at the time of electrical / optical conversion in the semiconductor laser diode 2 is converted into heat, and the temperature of the semiconductor laser diode 2 is raised. In order to avoid such a rise in temperature, a temperature detector such as a thermistor resistor is provided around the semiconductor laser diode 2, whereby the temperature around the semiconductor laser diode is detected.
The current supplied to the Peltier device electronic cooler 4 is controlled.
The heat absorption / dissipation amount of the Peltier element electronic cooler 4 is controlled according to the supplied power, and the semiconductor laser diode is always kept at a constant temperature. Usually, the first dielectric plate substrate 41 provided on the semiconductor laser diode 2 side has a heat absorbing function, and the second dielectric plate substrate 42 provided on the module package 1 side has a heat dissipation function. With the above configuration, the temperature rise of the semiconductor laser diode due to the heat generated from the semiconductor laser diode 2 is suppressed, and stable laser oscillation can be obtained.

However, as described above, in the conventional semiconductor laser module, the electronic cooler, the ground line, and the like constituting the module form a resonance circuit, and the input modulation signal has a frequency band centered around 1.6 GHz. In some cases, a phenomenon that the above circuit resonates and the optical frequency response level lowers occurs (FIG. 15). Then, as a result of examining the semiconductor laser module, it was found that an electrical equivalent circuit of the semiconductor laser module is shown in FIG. That is, the signal line is connected to the semiconductor laser diode (LD) via the inductance L1 by the bonding wire 91 and the inductance L2 by the bonding wire 92, relaying the lead pin and the transmission line in the form of a ceramic insert, and has an electrode pad. The capacitance component C3 is added in parallel with the LD. On the other hand, the ground line is connected from the chip mounting carrier 3 to the conductive package module through the bonding wire 93, the metallized transmission path 7 on the ceramic insert 6, and the via hole 10, and the inductance L3 of the bonding wire and the ceramic insert 6, It consists of a package-containing inductance component L4 including the inductance of the metallized transmission path 7 patterned on the ceramic insert 6, and is arranged in line with the capacitance C1 and C2 lines of the Peltier element dielectric plate substrate. Therefore, in the electrical equivalent circuit, the resonance frequency of the semiconductor laser module is

Fr = 1 / 2π {(L3 + L4) ((C1 / C2 / C1 + C2) + C3)} (Formula 1)

According to the above equation (1), if the parasitic inductance (L3 + L4) of the ground line is reduced, the resonance frequency fr increases, that is, the resonance frequency is shifted from 1.6 GHz to a high band, and the characteristic of the modulation region near 1.6 GHz is obtained. Is considered to be able to be improved. Therefore, means for directly connecting the chip mounting carrier and the module package with a metal member having a large cross-sectional area to reduce L3 + L4 has been studied. Are directly connected, the parasitic inductance (L3 + L
Although 4) is reduced, the Peltier element cooler absorbs heat from the chip-mounted carrier, and the heat radiated to the module package returns to the chip-mounted carrier again through the metal member, thereby causing a heat circulating phenomenon. The cooling effect of the laser diode was reduced and stable laser oscillation became difficult.

Therefore, the present invention reduces the parasitic inductance (L3 + L4) of the ground line without lowering the cooling effect of the semiconductor laser module, shifts the resonance frequency to a high frequency range, and is structurally and characteristically stable. A semiconductor laser module with an electronic cooler is provided. FIG. 1 is a cross-sectional view of a semiconductor laser module according to Embodiment 1 of the present invention. In the drawing, portions denoted by the same reference numerals as those in FIG. 13 indicate the same or corresponding portions. In the first embodiment, the first connection means 11 has a structure in which the first connection means 11 extends from the inner bottom portion 100 of the module package 1 directly to the vicinity of the upper surface of the chip mounting carrier 3 without passing through the metallized transmission path 7 or the like. The second connecting means 94 is provided in the first connecting means 1.
1 is electrically connected between the chip mounting carrier 3 and is constituted by, for example, a bonding wire. Therefore, between the chip mounting carrier 3 and the inner bottom part of the module package 1, the conductive first and second connection means 11, 9 are provided.
4 through the bonding wire 9
3. It is different from the conventional structure (FIG. 13) connected via the metallized transmission path 7 and via hole 10. Here, the module package 1 has an outer portion on the bottom,
Since it is used by being electrically connected to a metal housing (ground) of a transmitter unit provided outside, for example, the first
The connecting means 11 is connected to the inner bottom 10 of the module package 1.
It is preferably provided at 0. That is, when the first connection means 11 is provided at a position other than the inner bottom portion 100 of the module package 1, for example, when the first connection means 11 is provided on the side wall, the ground line is connected to the ground potential of the module package 1 directly connected to the ground potential. The bottom 100 is connected to the first and second connection means via the side wall of the module package 1, thereby generating unnecessary parasitic inductance on the side wall of the module package 1. For this reason, even if the inductance is reduced by increasing the cross-sectional area of the first connection means 11, it is difficult to sufficiently reduce the inductance of the entire ground line due to the occurrence of the parasitic inductance. Therefore, in the present embodiment, the first connection means 1 is directly provided on the inner bottom 100 of the module package 1 which is directly connected to the ground potential.
1 is provided to prevent generation of unnecessary parasitic inductance. Further, when the first connection means 11 is provided on the side wall of the module package 1, it is difficult to obtain a sufficient mounting strength with good reproducibility due to the structure in which the first connection means is bonded to the side wall. It was also difficult to obtain sufficient reliability due to a large change in strength and the like.

FIG. 2 is an electrical equivalent circuit diagram of the semiconductor laser module shown in FIG. 1. In FIG. 2, the same reference numerals as those in FIG. 14 indicate the same circuit elements. Inductance L3 generated in 93, metallized transmission path 7, via hole 10, and inductance L4 generated in module package 1
Is the inductance L5 generated in the second connection means,
It is replaced by the inductance L6 generated in the connection means. The resonance frequency of the electrical equivalent circuit shown in FIG.

Fr = 1 / 2π {(L5 + L6) ((C1 / C2 / C1 + C2) + C3)} (Expression 2) In the present embodiment, the first connection means 11
Since it is connected to the inner bottom portion 100 of the module package 1 and is formed of a metal block having a sufficiently large cross-sectional area, the inductance generated in the first connection means 11 is extremely small, and as a result, L6 can be reduced. it can. The first connection means 11 is formed so as to protrude from the inner bottom 100 of the module package 1 to the vicinity of the chip mounting carrier 3, for example, wire bonding for connecting the first connection means 11 and the chip mounting carrier 3. The length of the conductive second connection means 94 made of, for example, can be reduced. Therefore, even if the second connecting means 94 is formed of a bonding wire or the like having a small cross-sectional area, the occurrence of the parasitic inductance depending on the length can be reduced, and as a result, L5 can be reduced. On the other hand, the heat recirculation phenomenon in which heat is absorbed from the chip mounting carrier 3 by the Peltier element cooler 4 and the heat radiated to the module package 1 returns to the chip mounting carrier 3 through the ground line is caused by the second connection. This can be prevented by reducing the cross-sectional area of the means.

A comparison between the calculated value of the resonance frequency of the semiconductor module having the conventional structure (FIGS. 13 and 14) and the calculated value of the resonance frequency of the semiconductor laser module (FIGS. 1 and 2) according to the present embodiment will be described below. . In the conventional structure, the electrode pad 5
Is usually composed of a material with a low dielectric constant such as alumina,
The size is 1.8 × 1.8 × t1.0 mm, and C3 is about 0.26 pF. The upper and lower dielectric plates of the Peltier device 4 are 6 × 10 × t 0.45 mm, and C
1 and C2 are about 10.5 pF. The bonding wire 93 is usually 25 μm in diameter and about 3 mm in length.
Are formed in parallel, L3 is 0.5
It is about nH. The package-containing inductance L4 generated in the metallized transmission path 7, the via hole 10, and the module package 1 is about 1.2 nH.
Therefore, by substituting these values into Equation 1, the resonance frequency fr becomes about 1.6 GHz, which is in good agreement with the actually measured value shown in FIG.

On the other hand, in the first embodiment, C
1, C2 and C3 are the same as the conventional structure,
Inductance components generated in the second connection means 94 when six gold wires each having a diameter of 25 μm and a length of 0.5 mm are arranged as the second connection means 94 at about 10.5 pF, 10.5 pF, and 0.26 pF. L5 is 0.1
It is about nH. On the other hand, the package-containing inductance component L6 including the first connection means is estimated to be about 0.1 nH. Therefore, from Equation 2, the resonance frequency fr is 4.8.
It turns out to be about GHz, and it can be seen that resonance in the 1-2 GHz channel band can be avoided.

FIG. 3 shows the first and second connection means 1.
The measurement results of the small signal light frequency response of the semiconductor laser module according to the present embodiment formed by using Nos. 1, 94 are shown. In the figure, the vertical axis shows the optical frequency response, and the horizontal axis shows the frequency. As is clear from FIG. 3, the present measurement result agrees well with the above calculation result, and the center frequency at which the optical frequency response is degraded due to the resonance phenomenon is changed from the vicinity of 1.6 GHz of the conventional structure by 5
The band is shifted to the vicinity of GHz to improve the limit of modulation characteristics.

On the other hand, the second connecting means has a diameter of 25 μm.
Since the bonding wire has a small diameter of m, the thermal resistance between the module package 1 and the chip mounting carrier 3 can be increased. Therefore, the heat transfer between the two can be suppressed low, and the heat radiated from the lower surface of the Peltier element electronic cooler to the module package 1 is first and second.
It is possible to prevent a circulating phenomenon of heat circulated to the chip-mounted carrier 3 through the second connecting means 11 and 94, and to obtain a sufficient cooling effect without lowering the heat exchange efficiency of the Peltier element electronic cooler 4. It becomes possible.

As described above, according to the first embodiment, the area between the module package 3 and the chip mounting carrier 3 that extends from the inner bottom 100 of the module package 3 to the vicinity of the chip mounting carrier 3 is large. The ground line is electrically connected in series by the conductive first connection means 11 and the conductive second connection means 94 having a short and small cross-sectional area for connecting the first connection means and the chip mounting carrier. By forming the semiconductor module, the resonance frequency of the semiconductor module can be shifted to a higher frequency range without lowering the heat exchange efficiency of the Peltier element, and the modulation limit can be improved. In particular, in the present embodiment, the first connection means 11 is provided directly on the inner bottom portion 100 of the module package 1 which is directly connected to the ground potential, thereby preventing generation of unnecessary parasitic inductance and shifting the resonance frequency to a high frequency range. Is performed effectively, and the mounting strength of the first connection means 11 can be obtained with good reproducibility, and a highly reliable semiconductor module can be manufactured. In the first embodiment, a bonding wire is used as the second connection means 94. However, a ribbon wire can be used instead, and the diameter, the number, and the length of the bonding wire are determined according to the embodiment. , Can be arbitrarily selected. Also,
The module package is preferably a butterfly-type package, and particularly preferably a butterfly-type package having a ceramic insert having a metal transmission line patterned on the surface through the opposing side wall of the module package. Further, a coaxial connector may be incorporated in a module package as the modulation signal transmission means.

Embodiment 2 FIG. 4 is a sectional view of the semiconductor laser module according to the second embodiment of the present invention.
In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts,
The first embodiment shown in FIG.
1 and 941 and 112 and 942. FIG. 5 is an electrical equivalent circuit diagram according to the second embodiment, in which the same reference numerals as in FIG.
The same or corresponding portions are shown, and the first embodiment shown in FIG.
51, L61 and L52, L62 in a parallel arrangement. L51, L61, L52,
L62 indicates an inductance component generated at 941, 111, 942, and 112, respectively. The resonance frequency of the electric equivalent circuit according to the present embodiment is:

[Equation 3] fr = 1 / 2π√ [{(L51 + L61) (L52 + L62) / (L51 + L61 + L52 + L62)} {(C1C2 / C1 + C2) + C3}] (Equation 3) expressed. Assuming that L5 = L51 = L52, L6 = L6
When the ground line where 1 = L62 is formed, the resonance frequency fr can be set to √2 times the resonance frequency obtained in the first embodiment.

As described above, in the second embodiment, by providing two sets of the ground lines constituted by the first and second connection means, the ground lines can be synthesized without lowering the heat exchange efficiency of the Peltier element. It is possible to reduce the inductance and shift the resonance frequency to a higher frequency. In the second embodiment, two ground lines are used. However, three or more ground lines may be used. By configuring the ground lines with more groups, the combined inductance of the ground lines can be further reduced. The resonance frequency can be shifted to a higher frequency.

Embodiment 3 FIG. 6 is a sectional view of the semiconductor laser module according to the third embodiment of the present invention.
In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts,
The first embodiment shown in FIG. 1 is different from the first embodiment in that ground lines 111 and 94 are first ground lines connected to the bottom of the module package, and second ground lines 112 and 9 are connected to the side wall of the module package.
5 in that 5 is added. FIG. 7 is an electrical equivalent circuit diagram of the semiconductor laser module according to the second embodiment. In the drawing, the same reference numerals as those in FIG. 2 indicate the same or corresponding parts. In addition to the inductances L5 and L6, L7 and L8 are connected in parallel.
Is added. L7 and L8 are inductance components generated in the second connection means 95 and the first connection means 112, respectively. The resonance frequency of the electric equivalent circuit according to the present embodiment is:

[Equation 4] fr = 1 / 2πL [{(L5 + L6) (L7 + L8) / (L5 + L6 + L7 + L8)} {(C1C2 / C1 + C2) + C3}] (Equation 4) expressed. As described above, the effect of reducing the combined inductance by providing the connecting means constituting the ground lines in parallel is not only when the plurality of ground lines connected to the bottom inside the module package are provided as shown in the second embodiment, It can also be obtained by setting a ground line on the side wall of the module package in addition to the bottom inside the module package. Therefore, the position for setting the ground line can be flexibly selected, and the flexibility of the module configuration can be improved.

As described above, in the third embodiment, in addition to the first ground lines 111 and 94 connected to the inner bottom of the module package, the ground lines are connected to the second ground line 112 connected to the side wall of the module package. With the addition of 95, the combined inductance of the ground lines is reduced and the resonance frequency is further shifted to a higher frequency range without lowering the heat exchange efficiency of the Peltier element, as compared with the case where one ground line is provided. It becomes possible. Further, the ground line to be added can be provided at a position other than the inner bottom of the module package, and the flexibility of the module configuration is improved.

Embodiment 4 FIG. FIG. 8 is a sectional view of the semiconductor laser module according to the fourth embodiment of the present invention.
In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts,
The first embodiment shown in FIG.
Is an integral structure with the first connection means 13 and has a first inner bottom 101 at the same height as the upper surface of the chip mounting carrier.
And the electronic cooler 4 on which the chip mounting carrier 3 is mounted.
In that it comprises a second inner bottom portion 102 for fixing the inner bottom. The electrical equivalent circuit diagram and the small signal light frequency response characteristics according to the present embodiment are the same as those in the first embodiment shown in FIGS.

As described above, in the fourth embodiment, it is possible to shift the resonance frequency to a higher frequency without lowering the heat exchange efficiency of the Peltier element,
Since the connecting means 13 has an integral structure with the module package 1 and does not have a connecting portion, it is possible to improve the reliability against impact and to improve the resistance of the connecting portion to deterioration over time. In addition, since the process of attaching and adjusting the first connection means 13 can be omitted, the manufacturing process of the semiconductor laser module can be simplified. Furthermore, since it is possible to prevent the occurrence of the contact inductance caused by the mounting failure of the first connection means 13, it is possible to prevent the inductance of the ground line from being deteriorated. Although the first inner bottom portion 101 serving as the first connecting means is provided at one position, a plurality of first inner bottom portions 101 serving as the first connecting means may be provided.

Embodiment 5 FIG. FIG. 9 is a sectional view of a semiconductor laser module according to a fifth embodiment of the present invention.
In the drawing, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts,
Embodiment 2 is different from Embodiment 1 in that the first connection means is a metal block 14 fixed to the inner bottom of the module package by a detachable fixing means. The electrical equivalent circuit diagram and the small signal light frequency response characteristics according to the present embodiment are the same as those of the first embodiment (FIGS. 2 and 3).

As described above, in the fifth embodiment, it is possible to shift the resonance frequency to a higher frequency without lowering the heat exchange efficiency of the Peltier element,
Since the metal block 14 serving as connection means is attached to the inner bottom of the module package 1 by detachable fixing means such as solder connection, in the process of manufacturing the semiconductor module, the Peltier device electronic cooler 4 and the chip mounting carrier 3 After adjusting the position of the components that require optical axis adjustment, such as condenser lens, optical isolator, optical fiber, etc., and fixing each member in a predetermined place, the above-mentioned metal block can be attached to secure working space. Becomes possible. Further, when it is necessary to readjust the positions of the above members, it is possible to easily remove the metal block and secure a work space.

Embodiment 6 FIG. In the sixth embodiment, the parasitic inductance (L3 + L4) of the ground line is increased, the resonance frequency is shifted to the low frequency side, and the structural and characteristics are reduced without lowering the heat exchange efficiency of the Peltier device of the semiconductor laser module. FIG. 10 is a diagram for providing a semiconductor laser module with an electronic cooler, which is more stable.
10 shows a cross-sectional view of a semiconductor laser module according to Embodiment 6 of the present invention. In the figure, the same reference numerals as those in FIG. 13 indicate the same or corresponding parts. In the semiconductor laser module according to the sixth embodiment shown in FIG. 10, the ground line is connected to the third connection means 15 such as a chip-type inductance element having a predetermined inductance value and the conductive material having a small cross-sectional area such as a bonding wire. It is different from the semiconductor laser module having the conventional structure shown in FIG. FIG. 11 is an electrical equivalent circuit diagram of the semiconductor laser module according to the first embodiment shown in FIG. 10. In FIG. 11, the same reference numerals as those in FIG. 14 denote the same circuit elements, and FIG. The inductance L3 generated in the bonding wire 93, the metallized transmission path 7, the via hole 10, and the inductance L4 generated in the module package 1 are the inductance L8 generated in the second connection means, the inductance generated in the third connection means and the module package 1. L9 has been replaced. The resonance frequency of the electrical equivalent circuit diagram according to the sixth embodiment is

Fr = 1 / 2π√ {(L9 + L10) ((C1 / C2 / C1 + C2) + C3)} (Equation 5) In the sixth embodiment, the third connection means 15
However, since it is configured to have a large inductance value, the combined inductance (L9 + L10) can be extremely increased.

The calculated value of the resonance frequency of the semiconductor module having the conventional structure (FIG. 13) is compared with the calculated value of the resonance frequency of the semiconductor laser module according to the sixth embodiment. In the sixth embodiment, C1, C2, and C3 are the same as the conventional structure, and are 10.5 pF, 10.
5 pF, about 0.26 pF, and the second connecting means 9
6 is a gold wire having a diameter of 25 μm and a length of 0.5 mm.
In this arrangement, the inductance component L10 generated in the second connection means 96 is about 0.1 nH. on the other hand,
The third connection means 15 has an inductance L9 of 33 nH.
Utilizing the chip-type inductance element. Therefore, from Equation 5, the resonance frequency fr of the resonance circuit is about 370 Hz, which can be shifted to a lower band than the 1-2 GHz channel band used for public communication.
It can be seen that resonance in the 2 GHz channel band can be avoided.

FIG. 12 shows the third and second connection means 1.
13 shows the measurement results of the small-signal optical frequency response of the semiconductor laser module according to the sixth embodiment using Nos. 5 and 96 as ground lines. In the figure, the vertical axis shows the optical frequency response, and the horizontal axis shows the frequency. As is clear from FIG. 12, this measurement result agrees well with the above calculation result, and the center frequency at which the optical frequency response is degraded due to the resonance phenomenon is changed from the vicinity of 1.6 GHz of the semiconductor laser module having the conventional structure (FIG. 13). ,
The frequency can be shifted to a low band near 300 MHz, and the deterioration of the modulation characteristic in the frequency region of approximately 700 MHz or higher is improved. On the other hand, the second connection means has a diameter of 2
Since the bonding wire has a small diameter of 5 μm, the thermal resistance between the module package 1 and the chip mounting carrier 3 can be increased as in the related art. For this reason, heat transfer between both can be suppressed low, and a sufficient cooling effect can be obtained.

As described above, according to the sixth embodiment, the space between the module package 3 and the chip mounting carrier 3 is connected to the inner bottom of the module package 3.
A ground line is formed by electrically connecting the connecting means 15 and the conductive second connecting means 96 having a small cross-sectional area for connecting the third connecting means and the chip mounting carrier to form a ground line. Without lowering the heat exchange efficiency, the resonance frequency of the semiconductor module is shifted to a lower frequency band, and is used in a public communication band of 0.8 to 2 GHz.
It is possible to prevent the modulation characteristics from deteriorating in the channel band.

In the sixth embodiment, a chip-type inductance element is used as the third electrical connection means 15, but a chip-type inductance element, a coil, a lead line, a wire, a metal, and the like, which can obtain a predetermined inductance value. It may be composed of one or a combination of two or more selected from a group of transmission line. For example, if the metallized transmission path 7 and via hole 10 on the ceramic insert 6 shown in FIG. 13 are used as a part of the third connection means,
A module having a structure similar to the conventional one can be realized. Further, in the sixth embodiment, the inductance value of the third connection means is set to 33 nH. However, the third connection means may have another predetermined inductance value. That is, if the third connection means having an inductance value of 10 nH or more is used, the resonance frequency can be made approximately 700 MHz or less.

In the first to sixth embodiments, the bonding wire is used as the second connection means. However, a ribbon wire can be used instead, and the diameter, the number, the length, and the like of the bonding wire are determined according to the embodiment. Can be arbitrarily selected according to the embodiment. Also, the above module package
It is preferably a butterfly type package, especially
Preferably, the butterfly package has a ceramic insert that penetrates the opposing side walls of the module package and has a metal transmission line patterned on the surface.

[0043]

As will be apparent from the following description, according to the present invention, a conductive first connection having a large cross-sectional area and extending from the bottom of the module package connected to the external ground plane to the vicinity of the chip mounting carrier. Forming a ground line by the first connecting means and the conductive second connecting means having a small cross-sectional area for connecting the chip connecting carrier to the chip mounting carrier, thereby preventing generation of unnecessary parasitic inductance in the ground line. However, the resonance frequency of the semiconductor module can be shifted to a higher frequency.
Further, since the first connecting means and the chip mounting carrier are connected by the second connecting means having a short and small cross-sectional area, a recirculation phenomenon in which heat is conducted from the module package to the chip mounting carrier through the ground line is prevented. It can also be suppressed.

On the other hand, the ground line is connected to the conductive second connection means having a predetermined inductance value and a small cross-sectional area, or the third connection means which is an inductance functional element having a predetermined inductance value, and the third connection means. Means and a second conductive means having a small cross-sectional area connecting the chip mounting carrier.
By increasing the parasitic inductance generated in the entire ground line, the resonance frequency of the semiconductor module can be shifted to a low frequency. Further, since the cross-sectional area of the second connecting means is small, it is also possible to suppress the recirculation phenomenon in which heat is conducted from the module package to the chip mounting carrier through the ground line.

That is, by using the semiconductor module structure according to the present invention, the inductance of the ground line is changed without lowering the cooling effect of the semiconductor laser module, and the resonance frequency of the semiconductor module is changed to an arbitrary frequency other than the desired channel frequency band. The high frequency region or the low frequency region can be shifted, whereby the center frequency at which the optical frequency response is degraded due to the resonance phenomenon can be shifted, and the modulation characteristics of the semiconductor module can be prevented from deteriorating.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor laser module with an electronic cooler according to a first embodiment of the present invention.

FIG. 2 is an electrical equivalent circuit diagram of the semiconductor laser module with the electronic cooler according to the first embodiment of the present invention.

FIG. 3 is a small-signal optical frequency response characteristic of the semiconductor laser module with an electronic cooler according to the first embodiment of the present invention;

FIG. 4 is a sectional view of a semiconductor laser module with an electronic cooler according to a second embodiment of the present invention.

FIG. 5 is an electrical equivalent circuit diagram of a semiconductor laser module with an electronic cooler according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a semiconductor laser module with an electronic cooler according to a third embodiment of the present invention.

FIG. 7 is an electrical equivalent circuit diagram of a semiconductor laser module with an electronic cooler according to a third embodiment of the present invention.

FIG. 8 is a sectional view of a semiconductor laser module with an electronic cooler according to a fourth embodiment of the present invention.

FIG. 9 is a sectional view of a semiconductor laser module with an electronic cooler according to a fifth embodiment of the present invention.

FIG. 10 is a sectional view of a semiconductor laser module with an electronic cooler according to a sixth embodiment of the present invention.

FIG. 11 is an electrical equivalent circuit diagram of a semiconductor laser module with an electronic cooler according to a sixth embodiment of the present invention.

FIG. 12 is a small-signal optical frequency response characteristic of the semiconductor laser module with the electronic cooler according to the sixth embodiment of the present invention.

FIG. 13 is a sectional view of a semiconductor laser module with an electronic cooler according to a conventional structure.

FIG. 14 is an electrical equivalent circuit diagram of a semiconductor laser module with an electronic cooler according to a conventional structure.

FIG. 15 shows a small signal light frequency response characteristic of the semiconductor laser module with the electronic cooler according to the conventional structure.

[Explanation of symbols]

1 module package, 2 semiconductor laser diode, 3 chip carrier, 4 Peltier element electronic cooler, 5 electrode pad, 6 ceramic insert, 7
Metallized transmission line, 8 lead pins, 91, 92, 9
3, 94, 95, 96, 941, 942 bonding wires, 10 via holes, 11, 111, 112 first connection means connected inside the module package, 1
2 First connection means connected to the side wall of the module package, 13 First connection means integral with the module package
Connecting means, 14 first connecting means which is detachably connected to the module package, 15 third connecting means, 41,
42 Peltier element electronic cooler dielectric plate substrate,
43 Peltier effect element, 100, 101, 102 Inner bottom of module package.

Claims (12)

[Claims] A semiconductor laser diode; a conductive chip-mounted carrier on which the semiconductor laser diode is mounted; an electronic cooler mounted with the chip-mounted carrier and absorbing heat from the chip-mounted carrier; A conductive module package in which a cooler is mounted on an inner bottom thereof and the heat absorbed by the electronic cooler is released; and a modulation signal transmitting means for transmitting an input modulation signal of a predetermined frequency to the semiconductor laser diode. An electronic cooler-equipped semiconductor laser module comprising at least a ground line for electrically connecting the module package and the chip-mounted carrier, wherein the ground line is changed by changing an inductance of the ground line. The resonance frequency of the resonance circuit composed of A semiconductor laser module with an electronic cooler, wherein the semiconductor laser module is shifted so as to deviate from a predetermined frequency band used in the transmitting means. 2. The method according to claim 1, wherein the ground line extends from the inner bottom of the module package to the vicinity of the chip mounting carrier, and has a large cross-sectional area and a conductive first connecting means; and the first connecting means and the chip mounting carrier. A conductive second connection means having a small cross-sectional area for connection, reducing an inductance of the ground line, and using a resonance frequency of a resonance circuit including the ground line in the modulation signal transmission means. 2. The semiconductor laser module with an electronic cooler according to claim 1, wherein the semiconductor laser module is shifted to a higher frequency range than a predetermined frequency band. 3. The semiconductor laser module with an electronic cooler according to claim 2, wherein said first connection means is formed integrally with an inner bottom portion of said module package. 4. The first connecting means includes: a part of an inner bottom of the module package extending to a height near an upper surface of the chip mounting carrier; and a connecting bottom for connecting the second connecting means to the upper surface. 4. The semiconductor laser module with an electronic cooler according to claim 3, comprising: 5. The semiconductor laser module with an electronic cooler according to claim 2, wherein said first connecting means is a plate-shaped metal block fixed to said module package by a fixing means detachable. . 6. The plate-shaped metal block is made of nickel,
The semiconductor laser module with an electronic cooler according to claim 5, wherein the semiconductor laser module is made of an alloy mainly containing iron or cobalt or an alloy mainly containing copper or tungsten. 7. The ground line has a conductive second connection means having a small sectional area for connecting the module package and the chip mounting carrier, or has a predetermined inductance value provided on the module package. A third connecting means, and a conductive second connecting means having a small cross-sectional area for connecting the third connecting means and the chip mounting carrier; increasing an inductance of the ground line, 2. The semiconductor laser module with an electronic cooler according to claim 1, wherein the resonance frequency of the resonance circuit including the semiconductor laser is shifted to a frequency lower than a predetermined frequency band used in the modulation signal transmission means. 8. The semiconductor laser module with an electronic cooler according to claim 7, wherein the inductance of the ground line is 10 nH or more. 9. The method as claimed in claim 9, wherein the third connection means comprises one or a combination of two or more selected from the group consisting of a coil, an inductance chip, a lead line, a wire, and a metal transmission line. A semiconductor laser module with an electronic cooler according to claim 7. 10. The semiconductor laser module with an electronic cooler according to claim 2, wherein said second connection means comprises a bonding wire or a ribbon wire. 11. The electronic cooler is in contact with the chip mounting carrier and the module package, respectively, and is made of any one of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), and calcium titanate (CaTiO ₃ ). The semiconductor laser module with an electronic cooler according to any one of claims 2 to 9, comprising a dielectric substrate made of a ceramic material described above and a Peltier effect element sandwiched between said dielectric substrates. 12. The modulation signal transmitting means comprises a metal transmission line formed on a ceramic insert penetrating through the module package, or a coaxial connector fixed to the module package. 10. The semiconductor laser module with an electronic cooler according to any one of 2 to 9.