JP6848161B2 - Optical module - Google Patents

Description

The present invention relates to an optical module.

Patent Document 1 describes a technique relating to an optical semiconductor module. This optical semiconductor module includes a laser diode, an optical system that emits light output from the laser diode toward the outside of the case, and a photodiode that receives a part of the light output from the laser diode.

Japanese Unexamined Patent Publication No. 05-327031

In recent years, in optical communication systems, a so-called wavelength division multiplexing technique has been used in which a plurality of signal lights having different wavelengths are superimposed and transmitted. In this way, when a plurality of signal lights are superposed and transmitted, the plurality of signal lights output from the plurality of light emitting elements are combined by the optical system and output to the optical fiber. Further, in order to monitor the intensity of each signal light, a plurality of light receiving elements (photodiodes) are arranged in the optical module. The size of the optical module is determined by the standard, and the smaller the space for accommodating a plurality of light receiving elements, the better.

The present invention has been made in view of such problems, and an object of the present invention is to provide an optical module capable of reducing a space for accommodating a plurality of light receiving elements.

In order to solve the above-mentioned problems, the optical module according to the embodiment includes a first corner portion and a second corner portion diagonally located on a rectangular substrate, and the first corner portion is more than the center of the substrate. A light receiving portion having a light receiving portion having a center at a position biased toward the center, a first electrode arranged at a position biased to a second corner portion from the center of the substrate, and a second electrode arranged at a position biased to another region of the substrate. A plurality of elements are provided, and the plurality of light receiving elements are mounted on one carrier. The first and second light receiving elements arranged at both ends of the carrier have a first corner portion of each second. They are arranged closer to the edges of the carrier than to the corners.

According to the optical module according to the present invention, the space for accommodating a plurality of light receiving elements can be reduced.

FIG. 1 is a plan view showing an internal structure of an optical module according to an embodiment. FIG. 2 is a plan view showing a part of FIG. 1 in an enlarged manner. FIG. 3 is a side view schematically showing a part of the internal structure of the optical module. FIG. 4 is a plan view showing a detailed configuration of the light emitting unit. FIG. 5 is an enlarged plan view showing the configurations of the carrier and the plurality of light receiving elements. FIG. 6 is an enlarged plan view showing one light receiving element. FIG. 7 is a plan view showing a state of wire bonding between the first electrode pad and the second electrode pad of the light receiving element and the wiring board. FIG. 8 is an enlarged plan view of the carrier and the light receiving element group according to the first modification. FIG. 9 is an enlarged plan view of the carrier and the light receiving element group according to the second modification. FIG. 10 is a plan view showing a carrier and a light receiving element group of an optical module as a comparative example.

[Explanation of Embodiments of the Present Invention]
First, the contents of the embodiments of the present invention will be listed and described. The optical module according to one embodiment includes a first corner portion and a second corner portion diagonally located on a rectangular substrate, and has a center at a position biased toward the first corner portion rather than the center of the substrate. It has a plurality of light receiving elements having a portion, a first electrode arranged at a position biased to a second corner portion from the center of the substrate, and a second electrode arranged in another region of the substrate, and a plurality of light receiving elements. The elements are mounted on one carrier, and each of the first and second light receiving elements arranged at both ends of the carrier has a first corner portion at the end portion of the carrier rather than a second corner portion. They are arranged in a close relationship.

In this optical module, each of the first and second light receiving elements arranged at both ends of the carrier is arranged so that the first corner portion is closer to the end portion of the carrier than the second corner portion. As a result, the light receiving regions of the first and second light receiving elements are arranged on the end side of the carrier, and the first electrode is arranged on the opposite side. According to such a configuration, the distance between the first and second light receiving elements can be shortened, and the space for accommodating the plurality of light receiving elements can be reduced.

Further, in the above optical module, third and fourth light receiving elements are arranged in a region between the first and second light receiving elements on the carrier, and each of the third and fourth light receiving elements has a third light receiving element. The two corners may be arranged closer to each other than the first corner.

Further, in the above optical module, third and fourth light receiving elements are arranged in a region between the first and second light receiving elements on the carrier, and each of the third and fourth light receiving elements has a third light receiving element. The first corners may be arranged closer to each other than the second corner.

Further, in the above optical module, a plurality of optical axes corresponding to each of the plurality of light receiving elements may be arranged parallel to the mounting surface of the carrier.

[Details of Embodiments of the present invention]
Specific examples of the optical module according to the embodiment of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to these examples, and is indicated by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. In the following description, the same elements will be designated by the same reference numerals in the description of the drawings, and duplicate description will be omitted.

FIG. 1 is a plan view showing the internal structure of the optical module 1A according to the embodiment. FIG. 2 is a plan view showing a part of FIG. 1 in an enlarged manner. FIG. 3 is a side view schematically showing a part of the internal structure of the optical module 1A. The optical module 1A is a light emitting module (TOSA; Transmitter Optical SubAssembly) including a rectangular parallelepiped housing 2 and a columnar optical coupling portion 3 having a flange.

Inside the optical module 1A, there are N light emitting parts 11a to 11d (N is an integer of 2 or more), N first lenses 12a to 12d, carriers 13, and N light receiving elements (photodiodes, PD) 14a. ~ 14d, N second lenses 15a to 15d, a combiner optical system 19, and wiring boards 21 and 22 are provided. In one example, the optical module 1A is a 4-channel (N = 4) light emitting module. The light emitting units 11a to 11d, the first lenses 12a to 12d, the carrier 13, the second lenses 15a to 15d, the combined wave optical system 19, and the wiring boards 21 and 22 are the base members 7 provided inside the housing 2. It is placed on a flat main surface.

Further, the housing 2 has a feedthrough 2B. The feedthrough 2B penetrates the rear wall of the housing 2, and a plurality of terminals 25 for electrical connection with an external device are provided in the direction A1 in the portion of the feedthrough 2B outside the housing 2. They are provided side by side. A plurality of terminals 24 and N signal lines 23 constituting a coplanar line are provided in the feedthrough 2B portion inside the housing 2. The N signal lines 23 and the plurality of terminals 24 are electrically connected to the corresponding terminals 25, respectively.

In the optical module 1A, the light emitting units 11a to 11d that function as light sources are independently driven, and the light emitting units 11a to 11d individually output the signal lights La to Ld. As shown in FIGS. 1 and 2, the optical axes of the signal lights La to Ld are aligned along the first direction (arrow A1 in FIG. 2) and are parallel to each other. The drive signals to the light emitting units 11a to 11d are provided from the outside of the optical module 1A. The signal lights La to Ld are lights modulated according to the drive signal. The light emitting units 11a to 11d each include a semiconductor optical integrated element 30 in which a laser diode and a semiconductor optical modulator are integrated. The wavelengths of the signal lights La to Ld are, for example, 1.3 μm bands, and are different from each other.

The first lenses 12a to 12d are optically coupled to the light emitting units 11a to 11d, respectively. The signal lights La to Ld output from the light emitting units 11a to 11d are input to the first lenses 12a to 12d, respectively. The distance between the semiconductor light integrating elements 30 of the light emitting units 11a to 11d and the corresponding first lenses 12a to 12d is shorter than the focal length of the first lenses 12a to 12d. Therefore, as shown in FIG. 3, the first lenses 12a to 12d convert the signal lights La to Ld, which are divergent lights, into convergent lights.

The carrier 13 is a rectangular parallelepiped member extending in the longitudinal direction in the second direction (arrow A2 in FIG. 2) intersecting each optical axis of the signal lights La to Ld, and is a first lens 12a to 12d and a second lens 15a to. It is arranged on the optical path between 15d and 15d. The optical axes of the signal lights La to Ld are arranged parallel to the mounting surface 13a of the carrier 13. Further, as shown in FIG. 3, the carrier 13 has a dielectric multilayer film (beam splitter) 13b inclined with respect to each optical axis of the signal light La to Ld, and the dielectric multilayer film 13b is provided therein. When the signal lights La to Ld pass through 13b, each part of the signal lights La to Ld (for example, 5 to 10% of the light amount of the signal lights La to Ld) is branched. The PDs 14a to 14d are mounted on the mounting surface 13a of one carrier 13 and receive each part of the branched signal lights La to Ld to detect the light intensity of the signal lights La to Ld. PD14a to 14d are mounted on the carrier 13 so that their back surfaces and the mounting surface 13a of the carrier 13 face each other. PD14a to 14d receive a part of the signal light La to Ld branched by the dielectric multilayer film 13b on the back surface.

The second lenses 15a to 15d are optically coupled to the first lenses 12a to 12d with the carrier 13 interposed therebetween. The signal lights La to Ld output from the first lenses 12a to 12d pass through the carrier 13 to form a beam waist, and then are spread again and input to the second lenses 15a to 15d, respectively. The distance between the second lenses 15a to 15d and the beam waist of the signal lights La to Ld coincides with the focal length of the second lenses 15a to 15d. Therefore, the second lenses 15a to 15d convert the signal light La to Ld that is incident while spreading into collimated light.

The combined wave optical system 19 is optically coupled to the second lenses 15a to 15d, and combines the signal lights La to Ld with each other. As shown in FIG. 1, the combined wave optical system 19 of the present embodiment includes a first WDM filter 16, a second WDM filter 17, a mirror 18, and a polarization synthesizer 20. The mirror 18 is optically coupled to the second lenses 15a and 15b. The light reflecting surface of the mirror 18 is located on the optical axes of the second lenses 15a and 15b and is inclined with respect to these optical axes. The mirror 18 reflects the signal lights La and Lb in a direction intersecting these optical axes. The first WDM filter 16 is optically coupled to the second lens 15c. The wavelength selection surface of the first WDM filter 16 is located on the optical axis of the second lens 15c and is inclined with respect to the optical axis. The first WDM filter 16 transmits the signal light Lc from the second lens 15c and reflects the signal light La reflected by the mirror 18. As a result, the optical paths of the signal lights La and Lc coincide with each other, and the signal lights La and Lc are combined with each other to form the signal light Le. The second WDM filter 17 is optically coupled to the second lens 15d. The wavelength selection surface of the second WDM filter 17 is located on the optical axis of the second lens 15d and is inclined with respect to the optical axis. The second WDM filter 17 transmits the signal light Ld from the second lens 15d and reflects the signal light Lb reflected by the mirror 18. As a result, the optical paths of the signal lights Lb and Ld coincide with each other, and the signal lights Lb and Ld are combined with each other to become the signal light Lf.

The polarization synthesizer 20 is a light-transmitting plate-shaped member. An antireflection film 20a and a polarization filter film 20b are formed on one plate surface, and an antireflection film 20c and an antireflection film 20d are formed on the other plate surface. Signal light Le is input to the antireflection film 20a. The signal light Le passes through the inside of the polarization synthesizer 20 and reaches the reflection film 20c, is reflected by the reflection film 20c, and then reaches the polarization filter film 20b. On the other hand, the signal light Lf is input to the polarization filter film 20b. When one of the polarizing planes of the signal lights Le and Lf is rotated by 90 ° by a polarizer (not shown), the signal light Le is reflected by the polarization filter film 20b and the signal light Lf is transmitted through the polarization filter film 20b. To do. As a result, the signal lights Le and Lf are combined with each other to become the signal light Lg. The signal light Lg is output from the polarization synthesizer 20 through the antireflection film 20d, and is output to the outside of the housing 2 through a window provided on the side wall 2A of the housing 2.

The optical coupling unit 3 is a coaxial module having a lens 52 (see FIG. 3) and a phi stub. The lens 52 is optically coupled to the combined wave optical system 19. The phi stub holds an optical fiber F (see FIG. 3). The lens 52 collects the signal light Lg and guides it to the end face of the optical fiber F. The optical coupling portion 3 is centered with respect to the optical axis of the signal light Lg, and then fixed to the side wall 2A of the housing 2 by welding. Although not shown, the optical coupling portion 3 has a lens 52 and a phi stub. In addition, it may further have an optical isolator that blocks light from the outside.

FIG. 4 is a plan view showing a detailed configuration of the light emitting units 11a to 11d. The light emitting units 11a to 11d include a chip carrier 31 and a semiconductor optical integrated element 30 mounted on the chip carrier 31. The chip carrier 31 is composed of an insulator. The semiconductor optical integrated device 30 has a monolithic structure in which a laser diode and a semiconductor optical modulator are integrated on a common substrate. The semiconductor optical integrated device 30 has a pad 30a connected to the anode electrode of the laser diode and a pad 30c connected to the anode electrode 30b of the semiconductor light modulator. The pad 30a receives a DC bias current for driving the laser. The pad 30c receives a high frequency modulated signal modulated according to the transmitted signal.

A coplanar line 32, a bias pattern 35, and a terminal pattern 36, which are transmission lines, are provided on the main surface 31a of the chip carrier 31. The coplanar line 32 is electrically connected to the semiconductor optical integrated element 30 at one end thereof, and supplies a modulation signal to the semiconductor optical integrated element 30. Specifically, the coplanar line 32 includes a signal line 33 and a ground pattern 34. The signal line 33 is a conductive metal film that guides a modulated signal, and extends from a position closer to one end face 31e to a position closer to the other end face 31f. The portion of the signal line 33 near the end surface 31f is a pad 33a for wire bonding. The pad 33a is electrically connected to the signal line 23 of the coplanar line provided in the feedthrough 2B of the housing 2 shown in FIG. 2 via a wire 46. Further, the portion of the signal line 33 near the end surface 31e is a pad 33b for wire bonding, and the pad 33b and the pad 30c of the semiconductor optical integration element 30 are electrically connected via a wire 41. To.

The ground pattern 34 is a conductive metal film provided on both sides of the signal line 33 at predetermined intervals, and is provided with a reference potential. The semiconductor optical integrated element 30 is mounted on the ground pattern 34, and the back electrode (cathode) of the semiconductor optical integrated element 30 is conductively connected to the ground pattern 34. The bias pattern 35 is a conductive metal film, and is electrically connected to the pad 30a of the semiconductor optical integration element 30 via a wire 43. The termination pattern 36 is a conductive metal film, and is electrically connected to the pad 30c of the semiconductor optical integration element 30 via a wire 42. The terminating pattern 36 and the ground pattern 34 are electrically connected via a terminating resistor chip 37.

A decoupling capacitor 38 is mounted on the ground pattern 34. The bottom electrode of the decoupling capacitor 38 is electrically connected to the ground pattern 34 via a conductive adhesive such as solder. The top electrode of the decoupling capacitor 38 is electrically connected to the bias pattern 35 via a wire 44. Further, the upper surface electrode of the decoupling capacitor 38 is electrically connected to any one of the plurality of terminals 24 provided in the feedthrough 2B of the housing 2 shown in FIG. 2 via a wire 45.

FIG. 5 is an enlarged plan view showing the configurations of the carrier 13 and the PDs 14a to 14d. The mounting surface 13a of the carrier 13 has a rectangular shape with the direction A2 as the longitudinal direction. The carrier 13 has a front surface 13c and a back surface 13d facing each other, and the front surface 13c and the back surface 13d both extend along the direction A2. In one example, the front surface 13c and the back surface 13d are parallel to each other and perpendicular to the flat main surface of the base member 7. However, the normal directions of the front surface 13c and the back surface 13d are slightly inclined with respect to the optical axes of the signal lights La to Ld. In other words, the direction A2 is slightly inclined with respect to the alignment direction A1 of the optical axes of the signal lights La to Ld. This is to prevent reflected return light on the front surface 13c and the back surface 13d. The carrier 13 further has one end surface 13e and the other end surface 13f facing each other. The one end surface 13e and the other end surface 13f are provided at one end and the other end in the direction A2 of the carrier 13, respectively, parallel to each other, and perpendicular to the main surface of the base member 7. The bottom surface of the carrier 13 is fixed to the main surface of the base member 7 via the resin adhesive 51.

PD14a to 14d constitute one light receiving element group 14, and are arranged in a row along the direction A2. This arrangement direction coincides with the longitudinal direction of the carrier 13. Here, FIG. 6 is an enlarged plan view of PD14a. The configurations of the other PDs 14b to 14d are the same as those of the PD14a shown in FIG.

The PD14a has a semiconductor substrate 61, and the semiconductor substrate 61 has a main surface 61a having a planar shape such as a rectangular shape (typically a square shape). The main surface 61a includes a first corner portion 61b, a second corner portion 61c, and a pair of third corner portions 61d. The second corner portion 61c is located diagonally with respect to the first corner portion 61b, and one third corner portion 61d is located at another diagonal position with respect to the other third corner portion 61d. One third corner 61d is adjacent to the first corner 61b and the second corner 61c, and the other third corner 61d is adjacent to the first corner 61b and the second corner 61c on the opposite side. Matching.

The PD14a further includes a light receiving region 62, a first electrode pad 63, and a pair of second electrode pads 64. The light receiving region 62 is provided as a semiconductor layer on the main surface 61a of the semiconductor substrate 61, and converts the light incident from the back surface side of the PD 14a into an electric signal. The planar shape of the light receiving region 62 is, for example, a circle. The light receiving region 62 is arranged closer to the first corner portion 61b with respect to the center of the main surface 61a. In other words, the light receiving region 62 has a center at a position biased toward the first corner portion 61b with respect to the center of the semiconductor substrate 61. It should be noted that the fact that the first corner portion 61b is arranged closer to the first corner portion 61b means that the first corner portion 61b, the second corner portion 61c, and the pair of third corner portions 61d are closest to the first corner portion 61b. This means that the center of the main surface 61a is not prevented from being included in the light receiving region 62.

The first electrode pad 63 is the first electrode in the present embodiment, and is a bonding pad provided as a metal film on the main surface 61a of the semiconductor substrate 61. The first electrode pad 63 is electrically connected to the first conductive semiconductor layer in the light receiving region 62 via a metal wiring formed on the main surface 61a. The first conductive type is, for example, the p type. The first electrode pad 63 is arranged closer to the second corner portion 61c side with respect to the center of the main surface 61a. In other words, the first electrode pad 63 is arranged at a position biased toward the second corner portion 61c with respect to the center of the semiconductor substrate 61. Typically, the first electrode pad 63 is arranged between the center of the main surface 61a and the second corner portion 61c.

The second electrode pad 64 is the second electrode in the present embodiment, and is a bonding pad provided as a metal film on the main surface 61a of the semiconductor substrate 61. The second electrode pad 64 is electrically connected to the second conductive semiconductor layer in the light receiving region 62. The second conductive type is, for example, n type. The second electrode pad 64 is arranged on the semiconductor substrate 61 in a region different from the region provided with the light receiving region 62 and the region provided with the first electrode pad 63. As an example, the one second electrode pad 64 is arranged so as to be closer to the one third corner portion 61d side with respect to the center of the main surface 61a. The other second electrode pad 64 is arranged so as to be closer to the other third corner portion 61d with respect to the center of the main surface 61a. In other words, each second electrode pad 64 is arranged at a position biased toward each third corner portion 61d with respect to the center of the semiconductor substrate 61. Typically, each second electrode pad 64 is arranged between the center of the main surface 61a and each third corner portion 61d.

See FIG. 5 again. The light receiving regions 62 of the PDs 14a to 14d are arranged at positions overlapping the optical axes of the signal lights La to Ld when viewed from a direction intersecting the direction A2 (for example, the normal direction of the mounting surface 13a). .. In one embodiment, the optical axes of the signal lights La to Ld pass through the center of the light receiving region 62 of the PDs 14a to 14d when viewed from the same direction. The PD14a (first light receiving element) arranged at one end of the carrier 13 is arranged so that the first corner portion 61b is closer to the end portion (one end surface 13e) of the carrier 13 than the second corner portion 61c. ing. Similarly, in the PD14d (second light receiving element) arranged at the other end of the carrier 13, the first corner 61b is closer to the end of the carrier 13 (the other end surface 13f) than the second corner 61c. Have been placed. More specifically, the distance between the first corner 61b of the PDs 14a and 14d located at the end of the light receiving element group 14 and the center of the light receiving element group 14 in the direction A2 is W1, and the second corner of the PDs 14a and 14d is defined as W1. When the distance between the unit 61c and the center of the light receiving element group 14 in the direction A2 is W2, the distance W1 is longer than the distance W2. In other words, the first corner portion 61b of the PDs 14a and 14d is located outside the second corner portion 61c in the direction A2. Therefore, the distance between the light receiving region 62 of the PDs 14a and 14d and the center of the light receiving element group 14 is longer than the distance between the first electrode pad 63 and the center of the light receiving element group 14, and these light receiving regions 62 are located in the direction A2. It will be located outside the first electrode pad 63. Further, one side including the first corner portion 61b of the PDs 14a and 14d is along the rectangular end side of the mounting surface 13a (that is, the end faces 13e and 13f of the carrier 13), and is parallel to the end side in one example.

In this embodiment, PD14b (third light receiving element) and PD14c (fourth light receiving element) are arranged in the region between PD14a and 14d on the carrier 13. Then, in each of the PDs 14b and 14c, the second corner portions 61c are closer to each other than the first corner portion 61b (that is, the distance between the second corner portions 61c is closer than the distance between the first corner portions 61b). ) Are arranged in a relationship. More specifically, the distance in the direction A2 between the first corner portion 61b of the PD14b, 14c located inside the end of the light receiving element group 14 and the center of the light receiving element group 14 is W3, and the first of the PD14b, 14c. When the distance between the two corners 61c and the center of the light receiving element group 14 in the direction A2 is W4, the distance W3 is also longer than the distance W4. In other words, the first corner portion 61b of the PDs 14b, 14c is located outside the second corner portion 61c in the direction A2. Therefore, the distance between the light receiving region 62 of the PDs 14b and 14c and the center of the light receiving element group 14 is longer than the distance between the first electrode pad 63 and the center of the light receiving element group 14, and these light receiving regions 62 are located in the direction A2. It is located outside the first electrode pad 63.

FIG. 7 is a plan view showing a state of wire bonding between the first electrode pads 63 and the second electrode pads 64 of PD14a to 14d and the wiring boards 21 and 22. In the present embodiment, the first electrode pads 63 of the PDs 14a and 14b are connected to the wirings 21b and 21a of the wiring board 21 via the wires 47a and 47b, respectively. Similarly, the first electrode pads 63 of the PDs 14c and 14d are connected to the wirings 22a and 22b of the wiring board 22 via the wires 47c and 47d, respectively. Further, one second electrode pad 64 of PD14a is connected to one second electrode pad 64 of PD14b via a wire 48a. The other second electrode pad 64 of the PD 14b is connected to the one second electrode pad 64 of the PD 14c via the wire 48b. The other second electrode pad 64 of the PD 14c is connected to the one second electrode pad 64 of the PD 14d via the wire 48c. The other second electrode pad 64 of the PD 14d is connected to the wiring 22c of the wiring board 22 via the wire 48d. As described above, in the present embodiment, the second electrode pads 64 of the PDs 14b and 14c located inside the end of the light receiving element group 14 and the second electrode pads 64 of the adjacent PDs 14a and 14d are connected to the wires 48a and 48c. Are connected to each other via.

In the above description, the second electrode pad 64 of the PD 14b and the second electrode pad 64 of the PD 14c are connected via the wire 48b, but instead of this connection, the second electrode pad 64 of the PD 14a is wired. It may be connected to wiring other than the wirings 21a and 21b of the substrate 21. Each wiring of the wiring boards 21 and 22 is electrically connected to any of the plurality of terminals 24 of the feedthrough 2B via a wire (not shown).

The effect obtained by the optical module 1A of the present embodiment described above will be described. FIG. 10 is a plan view showing a carrier 13 of an optical module and a light receiving element group 14 as comparative examples. In this comparative example, PDs 14a to 14d of the light receiving element group 14 are arranged so as to face the same side.

However, in many cases, the size of the housing 2 is determined by the standard, so the smaller the space for accommodating the PDs 14a to 14d, the better. In particular, in the configuration as in this embodiment, spaces for installing the wiring boards 21 and 22 are required on both sides of the carrier 13, and it is also important to secure an area for the resin adhesive 51 to protrude. Therefore, the smaller the planar dimension of the carrier 13 (that is, the area of the mounting surface 13a) is, the more preferable it is. On the other hand, the light receiving regions 62 of the PDs 14a to 14d need to be arranged at positions overlapping with each optical axis when viewed from a direction intersecting the direction A2 (for example, the normal direction of the mounting surface 13a). Therefore, the distance between the light receiving regions 62 of the PDs 14a to 14d is defined by the distance between the optical axes of the signal lights La to Ld, and cannot be freely narrowed.

In such a configuration, in the optical module 1A of the present embodiment, the first corner portion 61b of each of the PDs 14a and 14d arranged at both ends of the carrier 13 is located at the end of the carrier 13 rather than the second corner portion 61c. They are arranged in a close relationship. That is, the distance W1 in the direction A2 between the first corner portion 61b of the PD14a, 14d and the center of the light receiving element group 14 is the distance W2 in the direction A2 between the second corner portion 61c of the PD14a, 14d and the center of the light receiving element group 14. Is longer than. As a result, the light receiving regions 62 of the PDs 14a and 14d are arranged on the end side of the carrier 13 (the end side of the light receiving element group 14), and the first electrode pad 63 is arranged on the opposite side (the center side of the light receiving element group 14). Will be done. As described above, the position of the light receiving region 62 is defined by the optical axis positions of the signal lights La to Ld, but according to such a configuration, the PDs 14a and 14d located outside the direction A2 are brought closer to each other (these are). The edge of the light receiving element group 14 can be brought closer to the center side of the light receiving element group 14), and the space for accommodating the PDs 14a to 14d (the area of the mounting surface 13a), particularly the width of the mounting surface 13a in the direction A2 can be reduced. it can.

Further, when the second electrode pad 64 is connected to the n-type semiconductor layer as in the present embodiment, the second electrode pad 64 of the PD14b and 14c and the second electrode pad 64 of the adjacent PD14a and 14d are connected to each other. They may be connected to each other via wires 48a and 48c. In this case, as compared with the case where the wire is formed from the PDs 14b and 14c to the outside of the light receiving element group 14 (for example, the wiring boards 21 and 22), the degree of crossing with other wires is reduced and the wire formation is facilitated. Can be done. If the second electrode pads 64 of the PD 14b and 14c are connected to each other via the wire 48b as in the present embodiment, it is not necessary to form a wire from the PD 14a (or 14d) to the outside of the light receiving element group 14, and the wire can be formed. The degree of crossing can be further reduced.

Further, as in the present embodiment, the carrier 13 may have a dielectric multilayer film 13b that partially branches from each signal light La to Ld. In such a case, the positional relationship between the optical axes of the signal lights La to Ld and the PDs 14a to 14d becomes as described above, and the configuration of the present embodiment becomes particularly useful.

Further, as in the present embodiment, the mounting surface 13a has a rectangular shape with the direction A2 as the longitudinal direction, and one side including the first corner portion 61b of the PDs 14a to 14d located at the end of the light receiving element group 14 is the said. It may be along the edge of the rectangle. As a result, the length of the mounting surface 13a in the longitudinal direction can be shortened, and the optical module 1A can be miniaturized.

(First modification)
FIG. 8 is an enlarged plan view of the carrier 13 and the light receiving element group 14 according to the first modification. The difference between this modification and the above embodiment is the orientation of PD14b, 14c. As shown in FIG. 5, each of the PDs 14b and 14c of the above embodiment is arranged so that the second corner portions 61c are closer to each other than the first corner portion 61b. On the other hand, in each of PD14b and 14c of this modification, as shown in FIG. 8, the first corner portions 61b are closer to each other than the second corner portion 61c (that is, the distance between the first corner portions 61b). However, they are arranged in a relationship (closer than the distance between the second corner portions 61c). More specifically, in the above embodiment, the distance W3 between the first corner portion 61b of the PD 14b, 14c and the center of the light receiving element group 14 is the center of the second corner portion 61c of the PD 14b, 14c and the light receiving element group 14. Distance is longer than W4. On the other hand, in this modification, the distance W3 is shorter than the distance W4. In other words, the first corner portion 61b of the PDs 14b, 14c is located inside the second corner portion 61c in the direction A2. Therefore, the distance between the light receiving region 62 of the PDs 14b and 14c and the center of the light receiving element group 14 is shorter than the distance between the first electrode pad 63 and the center of the light receiving element group 14, and these light receiving regions 62 are located in the direction A2. It is located inside the first electrode pad 63.

According to this modification, since the first electrode pads 63 of the PDs 14b and 14c are close to the ends of the light receiving element group 14, the distance between the first electrode pads 63 of the PDs 14b and 14c and the wiring boards 21 and 22 is shortened. The formation of the wires 47b and 47c (see FIG. 7) on the first electrode pad 63 can be facilitated.

(Second modification)
FIG. 9 is an enlarged plan view of the carrier 13 and the light receiving element group 14 according to the second modification. The difference between this modification and the above embodiment is the orientation of the PDs 14b and 14c located inside the end of the light receiving element group 14. In this modification, each side of the rectangles of PD14b and 14c is inclined with respect to the direction A2 and its orthogonal direction. Then, in the direction A2, the first corner portion 61b and the second corner portion 61c are located between one of the third corner portions 61d of the PDs 14b and 14c and the other third corner portion 61d. In one example, the distance W3 between the first corner portion 61b of the PD 14b, 14c and the center of the light receiving element group 14 is equal to the distance W4 between the second corner portion 61c of the PD 14b, 14c and the center of the light receiving element group 14.

According to this modification, the distances between the second electrode pads 64 of the PDs 14b and 14c and the second electrode pads 64 of the PDs 14b and 14c and the second electrode pads 64 of the PDs 14a and 14d are close to each other, so that the wires 48a to 48c Can be easily formed.

The optical module according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, the above-described embodiments and modifications may be combined with each other according to the required purpose and effect. Further, in the above embodiment, the case where the optical module includes four light receiving elements is illustrated, but the present invention can be applied to an optical module including two or more arbitrary number of light receiving elements.

1A ... Optical module, 2 ... Housing, 2A ... Side wall, 2B ... Feed-through, 3 ... Optical coupling part, 7 ... Base member, 13 ... Carrier, 13a ... Mounting surface, 13b ... Dielectric multilayer film, 13c ... Front surface, 13d ... back surface, 13e ... one end surface, 13f ... other end surface, 14 ... light receiving element group, 14a to 14d ... light receiving element (PD), 15a to 15d ... second lens, 16 ... first WDM filter, 17 ... second WDM filter, 18 ... Mirror, 19 ... Combined optical system, 20 ... Polarization synthesizer, 20a ... Antireflection film, 20b ... Polarization filter film, 20c ... Reflective film, 20d ... Antireflection film, 21,22 ... Wiring substrate, 21a , 21b, 22a-22c ... wiring, 23 ... signal line, 24, 25 ... terminals, 30 ... semiconductor optical integrated element, 30a ... pad, 30b ... anode electrode, 30c ... pad, 31 ... chip carrier, 31a ... main surface, 31e ... End face, 31f ... End face, 32 ... Coplanar line, 33 ... Signal line, 33a, 33b ... Pad, 34 ... Ground pattern, 35 ... Bias pattern, 36 ... Termination pattern, 37 ... Termination resistance chip, 38 ... Decoupling capacitor 41-46, 47a-47d, 48a-48d ... Wire, 51 ... Resin adhesive, 52 ... Lens, 61 ... Semiconductor substrate, 61a ... Main surface, 61b ... First corner, 61c ... Second corner, 61d ... 3rd corner, 62 ... light receiving region, 63 ... 1st electrode pad, 64 ... 2nd electrode pad, A1 ... 1st direction, A2 ... 2nd direction, F ... optical fiber, La to Lg ... signal light.

Claims (4)

On the main surface of the rectangular substrate, a first corner portion and a second corner portion located diagonally, and a pair of third corner portions located diagonally different from the diagonal portion are provided, and the center of the substrate is provided. A light receiving portion having a center at a position biased toward the first corner portion, a first electrode arranged at a position biased toward the second corner portion rather than the center of the substrate, and the above-mentioned above from the center of the substrate. It has a plurality of light receiving elements having a pair of second electrodes arranged at positions biased to each of the pair of third corner portions on the main surface.
The plurality of light receiving elements are mounted on one carrier, and the plurality of light receiving elements are mounted on one carrier.
The first and second light receiving elements arranged at both ends of the carrier are arranged so that the first corner portion is closer to the end portion of the carrier than the second corner portion. Optical module. Third and fourth light receiving elements are arranged in the region between the first and second light receiving elements on the carrier, and each of the third and fourth light receiving elements has the second corners of each other. The optical module according to claim 1, wherein the optical modules are arranged closer to each other than the first corner portion. Third and fourth light receiving elements are arranged in the region between the first and second light receiving elements on the carrier, and each of the third and fourth light receiving elements has the first corners of each other. The optical module according to claim 1, wherein the optical modules are arranged closer to each other than the second corner portion. With multiple light emitting parts
The optical axes of the plurality of light emitting units corresponding to the plurality of light receiving elements pass through the carrier and are arranged parallel to the mounting surface of the carrier .
The carrier has a beam splitter that splits a part of the light output from each light emitting unit inside.
The optical module according to any one of claims 1 to 3 , wherein each light receiving element receives the branched part on the back surface facing the carrier.

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