JP2011108938A - To-can type tosa module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TO-CAN (Transistor Outlined Can) type TOSA (Transmitter Optical Sub-Assembly) module that does not generate abrupt variation in line width of a high-frequency signal when an optical semiconductor element as a compact component and a wide high-frequency line are connected to each other, and suppresses loss of the high-frequency signal. <P>SOLUTION: The TO-CAN type TOSA module includes: a stem to which a lead terminal is fixed with a dielectric; a relay line substrate mounted on the stem and having a first signal line to be connected to the lead terminal formed; a Peltier element as a cooling element mounted on the stem; a carrier body mounted on the Peltier element; a subcarrier having a projection portion projecting from the carrier body to above the relay line substrate, and fixed to the carrier body, an optical semiconductor element being mounted at a position overlapping the carrier body and a second signal line connected to the optical semiconductor element being formed to extend to the projection portion; and a wire connecting the first and second signal lines to each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a TO-CAN type TOSA module.

  With the recent expansion of use of the Internet, IP telephones, video downloads, etc., the required communication capacity is rapidly increasing, and the demand for optical modules used in these communication devices is expanding. In addition, the use of optical modules has further expanded as optical modules have begun to be used as parts in LAN devices installed in office buildings and ordinary homes. As the demand increases, it is becoming very important to control the cost of optical modules. In connection with this, standardization and development of optical module specifications are being promoted by actively considering sharing specifications of modules used in data communication and LAN.

  Further, against the background of the increase in the number of optical modules used per device, technical demands such as reducing power consumption and suppressing heat generated from the optical modules are increasing. Furthermore, since many optical modules are accommodated per apparatus, downsizing of the optical module is also an important examination theme. Regarding miniaturization of optical modules, a small module called TOSA (Transmitter Optical Sub-Assembly) has been widely used as a result of the development so far. As representative module forms for realizing a smaller TOSA compared to conventional optical modules, TO-CAN (Transistor Outlined CAN) type and BOX type have been developed, and have already been commercialized and used in the market. (Non-Patent Documents 1, 2, 3, 4).

  In general, the TO-CAN (Transistor Outlined CAN) type is often used in relatively low-spec applications where it is important to be cheaper than the function. Optical modules equipped with Peltier elements that require temperature control, etc. For applications that require relatively high-spec characteristics exceeding 10Gbps, the BOX type optical module configuration is used.

  As shown in FIG. 1, a conventional TO-CAN type TOSA module 50 includes a plurality of wiring terminals 2a, 2b, 2c,... An optical semiconductor element 1 or the like is mounted. The cup-shaped cap 5 integrated with the lens or the light extraction window 4 is resistance-welded to the stem 10 to seal the optical semiconductor element 1 or the like in the package. Further, a flexible printed circuit board 6 is provided on the bottom surface of the stem 10, and the module and other components are electrically connected via the flexible printed circuit board 6.

  The TO-CAN-type TOSA module 50 package shown in FIG. 1 is generally called a CAN-type optical module package because it has a CAN-like shape, and was originally developed as a small package for electronic devices. The TO-CAN type package is diverted for optical modules. The TO-CAN type optical module package can be manufactured by pressing, and the manufacturing cost is reduced because it has common specifications. Because it is small and has a small mounting space, and it is difficult to mount many components, it was common to use it as a module with a relatively small number of components. As a result, development of high-performance inexpensive CAN-type TOSA modules (low-cost development of high-performance optical modules) is awaited.

  To realize a high-performance CAN-type TOSA module, a TO-CAN-type TOSA module is equipped with a Peltier element, and a CAN-type TOSA module with characteristics exceeding 10 Gbps is being developed. An example of a conventional CAN-type TOSA module 50 equipped with a Peltier element and developed for applications exceeding 10 Gbps will be further described with reference to FIGS. The relay line substrate 111 is a substrate for relaying a high-frequency signal fed from the wiring terminal 2 a provided on the stem 10, and is a front surface of a part (hereinafter referred to as a nose) 10 d formed to protrude from the upper surface of the stem 10. It is fixed to. On the Peltier element 109, a subcarrier substrate 118 on which an optical semiconductor element (for example, a monolithically integrated laser diode (LD) and an optical modulator) 110a as a light emitting element is mounted, and the subcarrier substrate 118 is supported. A carrier 105 is placed.

  A lens 106 is mounted on the uppermost portion of the carrier 105, and is designed so that the output from the optical semiconductor element 110a can be efficiently extracted to the outside. When assembling a CAN-type optical module on which the Peltier element 109 is mounted, the carrier 105, the subcarrier substrate 118, and the like are mounted on the stem 10 via the Peltier element 109. In order to propagate a signal from the high-frequency electrical signal wiring terminal 2a configured in the stem 10 to the optical semiconductor element 110a mounted on the subcarrier substrate 118, center conductors 112a and 112b of several high-frequency lines, and It is essential to configure the ground electrode by connecting it with wire wirings 104, 103a, 103b and the like. Therefore, as shown in FIG. 1, a method of forming the high-frequency lines 112a and 112b on the relay line substrate 111 and the subcarrier substrate 118 is generally employed.

  A signal line 112b for supplying a high frequency signal to the optical semiconductor element 110a is provided on the subcarrier substrate 118, and the high frequency electric signal propagating from the relay line substrate 111 is efficiently transmitted to the optical semiconductor element 110a. The high-frequency line 112b on the carrier substrate and the signal line 112a of the relay line substrate 111 are designed. In the portion where the signal line 112a of the relay line substrate 111 and the signal line 112b of the subcarrier substrate 118 are opposed to each other, 112a and 112b are configured to have substantially the same line width so as to facilitate wire bonding. And the subcarrier substrate 118 are connected by wires 103a, 103b, and 104.

Dongchurl Kim et.al., `` Design and Fabrication of a Transmitter Optical Subassembly in 10-Gb / s Small-Form-Factor Pluggable Transceiver '', IEEE JORNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS.VOL. 12, No. 4, JULY / AUGUST 2006, pp776-782 H. Yamamoto et.al., ‘‘ Wide Temperature Range Operation of 10.7 Gbit / s Uncooled DFB-LD TOSA with Extremely High Eye-Mask Margin ’’, 2006 Electronic Components and Technology Conference, pp1548-1553 Norio Okada et.al., ‘‘10 .7 Gbit / s Low Power Consumption and Low Jitter EML TOSA Employing Interdigital Capacitor’ ’, European Conference on Optical Communications 2006 (ECOC 2006), 2006, pp1-2 Y. M. Tan et.al., ‘‘ Fabrication of Thermoelectric Cooler for Device Integration ’’, 2005 Electronics Packaging Technology Conference, pp802-805

  In the conventional TO-CAN type TOSA module, the carrier 105 and the subcarrier substrate 118 mounted on the Peltier element 109 have the same width as the Peltier element 109 so that the stress applied to the Peltier element 109 becomes uniform. Designed to. That is, the carrier 105 and the subcarrier substrate 118 that are wider than the Peltier element 109 are hardly designed to reduce the parts on the Peltier element 109 and reduce the load. Therefore, as shown in FIG. 1A, the relay line substrate is connected so that the high-frequency line 112a can be connected to the relay line 112b on the subcarrier substrate 118 at the same horizontal position as the mounting position of the optical semiconductor element 110a. It was common to configure 111 long.

  In order to reduce the loss of high-frequency electrical signals from the stem 10 to the optical semiconductor element 110a, it is advantageous to design the line width so as to reduce the conductor loss of the high-frequency lines 112a and 112b on the relay line substrate 111 and the subcarrier substrate. is there. Further, the width of the relay line 112b on the subcarrier substrate 118 at the connection portion with the relay line substrate 111 may have a line width that is as wide as possible in order to allow a certain amount of misalignment that occurs during the mounting operation. Needed. On the other hand, in order to secure a space for mounting an optical semiconductor chip, a termination resistor, and other components on the subcarrier substrate 118, and to align the sizes of the optical semiconductor chip and the high-frequency line, the relay line 112b on the subcarrier substrate 118 is In general, it has been practiced to reduce the line width to the width of the electrode on the chip 110a at the portion facing the optical semiconductor element 110a.

  In order to satisfy these requirements, conventionally, a design has been made in which the pattern width is changed in the high-frequency line 112 b of the subcarrier 118. That is, as described above, since the width of the subcarrier substrate 118 is about the width of the Peltier element 109, the pattern width conversion in the relay line 112b is steep. However, according to the development of a high-performance CAN-type TOSA module, it is clear that the reflection component of the high-frequency signal increases at the site where the line width of the relay line 112b is suddenly changed, leading to an increase in the loss of the high-frequency signal. It has become.

  An object of the present invention is to reduce the loss of a high-frequency signal without forming a sudden change in the line width of the high-frequency signal when connecting an optical semiconductor element such as an LD, which is a small component, and a wide high-frequency line. -To provide a CAN-type TOSA module.

  In order to solve the above-described problems, the invention described in claim 1 of the present invention includes a stem in which a lead terminal is fixed by a dielectric, and a first piece mounted on the stem and connected to the lead terminal. A relay line substrate on which one signal line is formed, a Peltier element as a cooling element placed on the stem, a carrier body placed on the Peltier element, and from the carrier body to the relay line board A second signal connected to the optical semiconductor element, wherein the optical semiconductor element is mounted on a portion of the subcarrier that is fixed to the carrier body and overlaps the carrier body. A TO-CAN type TOSA module comprising: a subcarrier formed so that a line extends to the protruding portion; and a wire connecting the first and second signal lines. It is.

  According to a second aspect of the present invention, in the TO-CAN type TOSA module according to the first aspect, the relay line substrate is fixed on a nose formed to protrude from the stem.

  According to a third aspect of the present invention, there is provided a stem in which a lead terminal is fixed by a dielectric, and a relay line substrate that is placed on the stem and is formed with a first signal line connected to the lead terminal. A Peltier element as a cooling element placed on the stem, a carrier body placed on the Peltier element, and a subcarrier fixed to the carrier body, the width of the Peltier element and the A pattern forming surface configured to be wider than the width of the carrier main body, and an optical semiconductor element is mounted on the pattern forming surface at a portion overlapping the carrier main body, and is connected to the optical semiconductor element. A subcarrier on which a signal line is formed; and a wire connecting the first and second signal lines, wherein the lead terminal extends vertically from a surface on which the Peltier element is placed. In addition, the first signal line and a connection portion between the first signal line and the second signal line are arranged so as to be aligned with the lead terminal. This is a TO-CAN type TOSA module.

  The invention described in claim 4 is the TO-CAN type TOSA module according to any one of claims 1 to 3, wherein the first signal line extends upward from an end of the lead terminal. The second signal line extends from the mounting portion of the optical semiconductor element in the main body part to the lower end of the protruding part so that the line width gradually increases.

  The invention described in claim 5 is the TO-CAN type TOSA module according to any one of claims 1 to 4, wherein the carrier has a ground pattern formed on both sides of the second signal line. And the relay line substrate has a ground pattern formed on both sides of the first signal line.

  According to the TO-CAN type TOSA module of the present invention, the optical semiconductor element, which is a small component, and a wide high-frequency line are connected by taking a sufficiently long path of the high-frequency line on the subcarrier substrate on which the optical semiconductor element is mounted. As a result, loss of the high frequency signal can be suppressed and good high frequency propagation characteristics can be obtained.

It is a front view showing a conventional TO-CAN type TOSA module. It is a front view which shows an example of the TO-CAN type TOSA module of the present invention. It is a top view which shows an example of the TO-CAN type TOSA module of the present invention. It is a right view which shows an example of the TO-CAN type TOSA module of the present invention. It is a perspective view which shows an example of the TO-CAN type TOSA module of the present invention. (A) is a figure which shows the propagation / reflection characteristic of the high frequency electric signal in the conventional TO-CAN type TOSA module, (b) is the propagation / reflection of the high frequency electric signal in the TO-CAN type TOSA module of the present invention. It is a figure which shows a characteristic.

  Hereinafter, embodiments of the present invention will be described in detail. 2 to 5 are diagrams showing an example of the TO-CAN type TOSA module according to the present invention. FIG. 2 is a front view, FIG. 3 is a plan view, FIG. 4 is a right side view, and FIG. ing. The TO-CAN type TOSA module 100 includes a dielectric 10 for hermetic sealing and a stem 10 having a plurality of wiring terminals (signal lead wires) 2a, 2b,. An optical semiconductor element 110a is mounted thereon. In the illustrated example, a high-frequency electric signal is passed through the wiring terminal 2a and has a diameter of, for example, 200 μm to 350 μm. A flexible printed circuit board (FPC) 6 is provided on the bottom surface of the stem 10.

  The material used for the stem 10 is a viewpoint of cooling the heat generated from the optical semiconductor element 110a that is a heat generation source and increasing the efficiency of dissipating the exhaust heat from the Peltier element 109 for keeping the temperature of the optical semiconductor element 110a constant. Then, it is required that the material has a high thermal conductivity. On the other hand, a glass material is used so that a distortion does not occur between the stem and the glass material for hermetic sealing provided around the wiring terminal 2a for passing a high-frequency electric signal due to a temperature change in the manufacturing process of the stem 10. It is required to use a material having a thermal expansion coefficient selected for the stem 10 in accordance with the thermal expansion coefficient. In the present embodiment, from the viewpoint of configuring the stem by combining materials having the optimum thermal conductivity and thermal expansion coefficient, the stem 10 has a two-layer configuration, and the upper layer 10a of the stem (the mounting surface side of the optical semiconductor element 110a and the like). Is made of a material having a high thermal conductivity, and the lower layer 10b of the stem (opposite the mounting surface of the optical semiconductor element 110a or the like) is made of a material that can match the thermal expansion coefficient with the glass material. For example, the stem upper layer 10a can be made of SPC (mild steel) having a high thermal conductivity, and the stem lower layer 10b can be made of FeNiCo (Kovar) whose thermal expansion coefficient matches that of a glass material.

  The stem upper layer 10a realizes characteristics as a high-frequency wiring terminal by designing the periphery of the wiring terminal 2a to be hollow. On the other hand, the stem lower layer 10b hermetically seals the stem 10 by arranging a glass material coaxially as the dielectric 11 around the wiring terminal 2a, and has both characteristics as a high-frequency wiring terminal. In the upper stem layer 10a, if the periphery of the wiring terminal 2a through which high-frequency electrical signals pass is hollow, that is, if low-permittivity air is used as a dielectric, the sectional area around the wiring terminal 2a can be reduced, and a small CAN module It is also preferable in that it is advantageous for securing a mounting space. The thickness of each layer of the stem 10 can be configured such that the stem upper layer 10a is 0.5 to 1.0 mm and the stem lower layer 10b is 0.5 to 2.0 mm, for example.

  The stem 10 is formed with a nose 10c protruding from the upper surface integrally or by attaching other parts. The stem 10 is kept at the ground potential by being grounded by a ground pin (not shown) provided on the bottom surface. The nose 10c is also kept at the same ground potential as the stem 10. The relay line substrate 101 is fixed to the front surface (front surface in the drawing) of the nose 10c by solder, and the signal line of the relay line substrate 101 is a high-frequency modulation signal (a driving signal for an optical semiconductor element) provided in the stem 10. ) Signal lead wire 2a. A relay line (signal line) 102a, a dielectric (a portion where the dielectric is exposed) 80 disposed on both sides of the relay line 102a, and a ground formed on both sides of the relay line 102a with the dielectric 80 interposed therebetween A pattern 102G is provided. The signal line 102a of the relay line substrate 101 can be configured to have a line width substantially the same as the diameter of the wiring terminal 2a from the lower end to the upper end of the relay line substrate 101. Therefore, the dielectric 80 also has an upper end from the lower end to the upper end. Can be configured without pattern conversion. It is preferable to secure a wide line width of the relay line substrate 101 and to configure it without pattern conversion from the viewpoint of reducing conductor loss and avoiding design complexity. The ground pattern 102G provided on the front surface of the relay line substrate 101 is grounded to a nose 10c disposed on the back side of the relay line substrate 101 through a through hole (not shown). Further, the ground pattern 102G of the relay line substrate 101 is connected to the stem 10 by solders S1 and S2 in the region close to the stem 10 so as to have the same potential as the stem 10 so that stable microwave propagation is possible. It has been strengthened.

  Here, the structure of the subcarrier on which the optical semiconductor chip is mounted will be described. In the module configuration of the present invention, the pattern forming surface of the subcarrier substrate 108 is formed to be wide, and when fixed to the carrier 105, a part thereof protrudes above the relay line substrate 101. The subcarrier substrate 108 is formed so that the optical semiconductor element 110a is mounted on the portion overlapping the carrier 105, and the relay line 102b connected to the optical semiconductor element 110a extends to the protruding portion. Further, the relay line substrate 101 is formed with a relay line 102a connected to a signal lead 2a that feeds a high-frequency signal fixed to the stem 10. The relay line 102 b extending to the lower end of the protruding portion of the subcarrier substrate 108 and the relay line 102 a extending to the upper end of the relay line substrate 101 are connected by wire bonding 104. That is, the subcarrier substrate 108 which has been conventionally equal to the width of the Peltier element and the carrier is configured to be wider than the width of the Peltier element 109 and the carrier 105, and the relay line 102a on the relay line substrate 101 and the relay line 102a And the connecting portion of the subcarrier substrate 108 to the relay line 102b are arranged so as to be aligned with the signal lead 2a. The signal lead 2a extends vertically from the mounting surface of the Peltier element 109 of the stem 10, and the relay line 102a on the relay line substrate 101 is a signal lead 2a that feeds a high-frequency signal fixed to the stem 10. It is connected to the. Here, being perpendicular to the mounting surface of the Peltier element 109 of the stem 10 means being parallel to a straight line connecting the stem 10 and the optical semiconductor element 110a with the shortest distance. In FIG. 3, the attachment position of the wire 104 provided at the connection portion between the relay line 102a (see FIG. 2) and the relay line 102b (see FIG. 2) on the subcarrier substrate 108 is aligned with the signal lead 2a. It is shown that. Therefore, as shown in FIG. 4, the surface of the subcarrier substrate 108 where the relay line 102b is formed and the surface of the relay line substrate 101 where the relay line 102a is formed are configured to be flush with each other. Further, an optical semiconductor element mounted on a Peltier element, a carrier, a subcarrier, or the like is N2 sealed with a cap integrated with the lens 4 as shown in FIG.

  In the conventional subcarrier, the high-frequency electric signal from the relay line substrate 101 is connected to the relay line substrate in the high-frequency line on the subcarrier for propagating to the optical semiconductor chip (in this embodiment, the optical modulator integrated LD chip). Whereas a sufficient distance to convert from the part pattern size to the connection part pattern size with the optical semiconductor chip could not be secured, the adoption of this structure resulted in a steep line width in the high-frequency line on the subcarrier. Thus, the pattern size can be changed smoothly. Therefore, design the pattern size near the junction with the relay line substrate and the pattern size closest to the optical semiconductor chip to the optimum size, and ensure sufficient pattern size conversion area to efficiently propagate high-frequency electrical signals. Is possible. (The effect will be described later) If there is a sudden change in the line width, the reflection due to the abrupt electric field field conversion will increase. As a result, the high-frequency propagation characteristics will be significantly reduced. The change in the line width can be eliminated, and the deterioration of the high frequency propagation characteristics can be suppressed.

  As shown in FIG. 2, the relay line 102 a and the relay line 102 b are axially connected to each other at the upper end portion of the relay line substrate 101 and the lower end portion of the protruding portion of the subcarrier substrate 108. Therefore, the relay line 102b on the subcarrier substrate 108 extends from the mounting portion of the LD 110a to the lower end of the protruding portion so that the line width gradually increases.

  Incidentally, in order to eliminate a sudden change in the line width, instead of increasing the length of the relay line 102b as described above, the length of the line is gradually increased while the length of the relay line 102a on the relay line substrate 101 is increased as in the prior art. It is also possible to adjust so as to be smaller. That is, the line width is adjusted on both the relay line substrate 101 and the subcarrier substrate 108. In this case, the relay lines 102a and 102b are connected to each other at a part where the line width is considerably small. However, the other end side of the relay line 102b must function as an electrode pad for contacting the probe during evaluation of the board, or when wiring is performed using an automatic wiring device or the like. In order to ensure the ease, the line width cannot be made too small. In addition, when connecting narrow lines, it is not preferable from the viewpoint that each alignment is required with high accuracy, or variation in connection loss due to variations in mounting work increases. Furthermore, it is preferable to adjust the line width in both the relay line substrate 101 and the subcarrier substrate 108 because the design complexity increases and the connection loss increases due to the line width change at the connection site. It is not a thing. Therefore, the mode of adjusting the line width in the relay line 102a on the relay line substrate 101 cannot be adopted.

  Further, in order to increase the length of the relay line 102b on the subcarrier substrate 108, the relay line substrate 101 is eliminated, and the relay line 102b of the subcarrier substrate 108 is directly connected to the signal terminal 2a provided on the stem 10. It is also possible to connect to the network. However, there are problems in that it is difficult to assemble an optical module having a Peltier element, and that heat radiated from the Peltier element 109 to the stem 10 is allowed to flow into the subcarrier substrate 108 again. .

  On the other hand, since the strength of the Peltier element 109 on which the carrier 105 and the subcarrier substrate 108 are mounted is not so strong, it has been conventionally considered that the carrier 105 and the subcarrier substrate 108 need to be configured as small as possible. However, since the carrier 105 and the subcarrier substrate 108 used in the TO-CAN type TOSA module 100 are sufficiently small, it has been found that there is no problem in the strength of the Peltier element 109 even if the size is slightly increased. It was.

  In this embodiment, the relay line 102 a on the relay line substrate 101 is connected to the relay line (signal line) 102 b on the subcarrier substrate 108 via the bonding wire 104. The relay line 102b is configured so that the line width of the connection portion is substantially the same as the line width of the relay line 102a so that the relay line 102b is connected to the relay line 102a without loss. For example, the line width at the connection portion between the relay lines 102a and 102b may be configured to be 100 μm or more in consideration of functioning as an electrode pad for contacting the probe during substrate evaluation. More preferably, in order to eliminate the pattern conversion of the relay line 102b on the relay line substrate 101 so that there is almost no conductor loss, the line width is almost the same as the width of the signal lead 2a. A ground pattern 120G is formed on both sides of the relay line 102b via a gap 81 so that the gap 81 between the signal line 102b and the ground pattern 120G has a desired characteristic impedance according to a change in the signal line width. Designed to. In order to stabilize the microwave propagating through the relay line 102b on the subcarrier substrate 108, the ground pattern 102G of the relay line substrate 101 and the ground pattern 120G of the subcarrier substrate 108 are connected by bonding wires 103a and 103b. Yes. Here, the characteristic impedance of the subcarrier substrate and the high-frequency line of the relay line substrate is generally designed to have the same characteristic impedance. When a broadband high-frequency signal is propagated, the characteristic impedance is 50Ω. Often designed to be The high-frequency line structure on the relay line substrate is not limited to the grounded coplanar structure, and may be a microstrip line structure or the like. The bonding wires 103a, 103b, and 104 are desirably shortened as much as possible in order to minimize deterioration of the high-frequency signal due to parasitic components such as parasitic reactance. From this point of view, the relay line substrate 101 and the subcarrier substrate It is desirable that the relay line substrate 101 and the subcarrier substrate 108 are arranged so that the surfaces of the signal lines 108 are on the same plane. However, a slight difference in height between the surfaces is allowed as long as deterioration of the high-frequency signal does not become a problem.

A Peltier element 109 as a cooling element is mounted on the stem 10, and a carrier 105 for mounting various components is mounted on the Peltier element 109. The carrier 105 has a lens 106 mounted on the upper portion thereof for collimated light from a laser diode (LD), and a subcarrier substrate 108 mounted on the lower side thereof. For example, CuW, which is a material having high member strength and high thermal conductivity, can be used for the carrier 105, and for example, AlN (aluminum nitride) or Al ₂ O ₃ (alumina) can be used for the subcarrier substrate 108. An optical semiconductor element 110a monolithically integrated with an LD unit and an optical modulator unit on the optical output side of the LD is mounted on the subcarrier substrate 108. In addition, a relay line 102b for driving and controlling the optical modulator unit, a termination A resistor 110b, a capacitor 110c, a thermistor 110d as a temperature sensor, and the like are mounted. The optical semiconductor element 110a is connected to the relay line 102b and is driven by a high-frequency signal input from the outside. What is necessary is just to comprise the line width of the relay line 102b in a connection part with the optical semiconductor element 110a by the size of 50 micrometers or more according to the size of the optical semiconductor element 110a. The optical output from the optical semiconductor element 110a is output from the chip through an optical modulator unit monolithically integrated on the optical output side of the LD. When the output light from the LD passes through the optical modulator unit, a modulation signal corresponding to the electrical signal applied from the relay line 102b to the modulator unit is added (superposed) to the optical signal. The resistance value, capacitance, and arrangement of the termination resistor 110b, the capacitor 110c, and the like are designed so as to efficiently draw a high-frequency electric signal from the relay line 102b to the optical modulator unit. The carrier 105 further includes a photodiode (PD) 110e for monitoring the laser output, a capacitor 110f, and the like. The operation state of the optical device is monitored from the outside, and influences such as fluctuations in the power supply circuit are exerted on the optical device. It is designed not to be able to. Although the case where the configuration of the optical semiconductor element 110a is an external modulation type has been described here, the configuration may be a direct modulation type that modulates the drive signal itself of the LD section.

  Next, the frequency characteristics of loss generated in the TO-CAN type TOSA module of the present invention will be described with reference to FIG. FIG. 6A is a diagram showing frequency characteristics of loss generated in the conventional TO-CAN type TOSA module, and FIG. 6B is a frequency of loss generated in the TO-CAN type TOSA module of the present invention. It is a figure which shows a characteristic. In both figures, the frequency characteristics are expressed using S parameters. In this simulation, the comparison is made under the condition that the total length of the high-frequency line on the relay line substrate and the high-frequency line on the subcarrier are the same.

  The S parameter is an index indicating the propagation efficiency and reflection characteristics of a high-frequency signal when a high-frequency electric signal is fed between any two points on the transmission line. In this simulation, the S-parameter is applied to the external substrate of the flexible printed circuit board 6. It evaluates and compares how much electric energy reaches (is reflected halfway) from the connection terminal (hereinafter referred to as port 1) to the termination resistor 110b (hereinafter referred to as port 2). The solid line is called propagation loss (Propagation Loss), or S21, and indicates the rate at which energy reaches from port 1 to port 2 in dB (decibel). S21 of 0 dB means that 100% energy is transmitted. On the other hand, the dotted line is called a return loss, or S11, and represents the ratio of energy reflected to the power supply source in dB. For example, if S11 is 0 dB, it indicates that the energy supplied by port 1 is not transmitted at all by port 2.

  When it is necessary to change the width of the high-frequency line abruptly in a narrow subcarrier like the conventional TO-CAN type TOSA module 50, as shown in FIG. The decline of That is, it can be seen that a significant propagation loss occurs in the high frequency region. On the other hand, it can be seen that the TO-CAN type TOSA module 100 of the present invention has lower propagation loss than the conventional TO-CAN type TOSA module 50 as shown in FIG. This is to improve the propagation efficiency of high-frequency electrical signals by designing so that the pattern change area of the high-frequency line is sufficiently ensured on the subcarrier by the configuration of the present invention so that the pattern change of the high-frequency line can be realized gradually. This is because of that. As shown in FIGS. 6 (a) and 6 (b), for example, when the reflection component indicated by the S11 parameter near 10.00 GHz is compared, the TO-CAN type TOSA module 100 of the present invention has a conventional structure. FIG. 6 shows that the reflection component is about 10 dB lower than that of the TO-CAN type TOSA module 50 and the drop in the propagation loss indicated by S21 in the vicinity of about 12 GHz in FIG. It is clear from the improvement in (b).

  As described above, according to the TO-CAN type TOSA module of the present invention, the path of the high-frequency line in the subcarrier substrate on which the optical semiconductor element is mounted is sufficiently long, so that the optical semiconductor element that is a small component and a wide high-frequency line are provided. There is no increase in the reflection component due to a sudden change in the line width in the high-frequency line connecting the line, and as a result, loss of the high-frequency signal can be suppressed and good high-frequency propagation characteristics can be obtained.

1 Optical semiconductor elements, etc. 2a, 2b ... Wiring terminals (lead pins)
4 Lens 5 Cap 6 Flexible printed circuit board (FPC)
10 Stem 10a Stem upper layer 10b Stem lower layer 10c, 10d Nose 11 Dielectric 50 for hermetic sealing (Conventional) TO-CAN type TOSA module 80, 81 Dielectric 100 (Invention) TO-CAN type TOSA module 101, 111 Relay line substrate 102a, 102b Relay line 112a, 112b Relay line 102G, 120G Ground pattern 103a, 103b ... Bonding wire 104 Bonding wire 105 Carrier 106 Lens 108, 118 Subcarrier substrate 109 Peltier element 110a Optical semiconductor element 110b Termination resistor 110c Capacitor 110d Thermistor 110e Photodiode (PD)
110f Capacitor S1, S2 Solder

Claims (5)

A stem with lead terminals fixed by a dielectric;
A relay line substrate mounted on the stem and forming a first signal line connected to the lead terminal;
A Peltier element as a cooling element placed on the stem;
A carrier body placed on the Peltier element;
A sub-carrier having a protruding portion protruding from the carrier main body above the relay line substrate and fixed to the carrier main body, wherein an optical semiconductor element is mounted on a portion overlapping the carrier main body, and the optical semiconductor element The second signal line connected to the subcarrier formed to extend to the protruding portion;
A wire connecting the first and second signal lines;
TO-CAN type TOSA module characterized by comprising   The TO-CAN type TOSA module according to claim 1, wherein the relay line substrate is supported by a nose protruding from the stem. A stem with lead terminals fixed by a dielectric;
A relay line substrate mounted on the stem and forming a first signal line connected to the lead terminal;
A Peltier element as a cooling element placed on the stem;
A carrier body placed on the Peltier element;
A subcarrier fixed to the carrier body, the pattern carrier having a pattern forming surface configured to be wider than the width of the Peltier element and the carrier body, and the pattern forming surface overlaps the carrier body A subcarrier on which an optical semiconductor element is mounted at a site and a second signal line connected to the optical semiconductor element is formed;
A wire connecting the first and second signal lines,
The lead terminal extends perpendicularly from the surface on which the Peltier element is placed, and the first signal line, and the connection portion between the first signal line and the second signal line, A TO-CAN type TOSA module configured to be aligned with the lead terminal. The first signal line extends upward from an end portion of the lead terminal,
The second signal line extends from the mounting portion of the optical semiconductor element of the main body part to the lower end of the protruding part so that the line width gradually increases. TO-CAN type TOSA module described in 1. The carrier has a ground pattern formed on both sides of the second signal line,
5. The TO-CAN type TOSA module according to claim 1, wherein the relay line substrate has ground patterns formed on both sides of the first signal line. 6.

Images