JP2007304267A - Optical parallel transmission module and optical parallel transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical parallel transmission module which can be stably produced by improving the yield during mounting, and also to provide an optical parallel transmission system. <P>SOLUTION: The optical parallel transmission module 1 is composed of: a CAN package 11 in which a light emitting element array 10 is hermetically sealed; an optical fiber connector 21 which fixedly holds an optical fiber array 20; and a lens barrel 31 which fixedly holds a single spherical lens 30 optically connecting the optical element array 10 to the optical fiber array 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical parallel transmission module and an optical parallel transmission system in which an optical element array and an optical fiber array are optically coupled, and in particular, it is possible to improve the yield at the time of mounting and to produce stably. The present invention relates to an optical parallel transmission module and an optical parallel transmission system.

  Conventionally, also in the optical communication field, an optical parallel data transmission technique has been demanded as the required data transmission capacity increases and the communication speed increases.

  In this optical parallel data transmission technology, in general, in order to reduce the size of the entire system, an optical parallel transmission module is constituted by an arrayed optical element and an arrayed light guide such as a ribbon optical fiber. In this optical parallel transmission module, it is necessary to obtain high optical coupling efficiency between the optical element array and the light guide path array and to hermetically seal the optical element array that is easily deteriorated by moisture or the like.

  As a conventional optical parallel transmission module of this type, for example, an optical semiconductor module having a structure in which a semiconductor laser array and an optical fiber array are coupled via a lens array has been proposed (for example, see Patent Document 1).

In the optical semiconductor module described in Patent Document 1, the semiconductor laser array and the lens array are arranged and fixed in the same package. The lens array is used as an end window member of the package, and the outer periphery of the lens array and the joint of the package are fixed with an airtight sealing material such as solder or low-melting glass. A package incorporating such a semiconductor laser array and a lens array and a package incorporating an optical fiber array are detachably fixed so as to have a light transmission relationship.
JP-A-5-323159 (FIGS. 1 to 4 and its description)

  Incidentally, in the optical semiconductor module described in Patent Document 1, the pitch of the lens array is set to the same dimension as the pitch of the semiconductor laser array, and light is collected by one lens for each pitch of the semiconductor laser array. It is like that.

  The size of one lens is about 250 μm. For this reason, in order to increase the optical coupling efficiency by connecting with high accuracy, it is necessary to set the interval between the semiconductor laser array and the lens array to an interval dimension of about 200 to 300 μm. Along with this, there is a problem in that the restrictions on mounting increase that the loop height of the wire bonding for electrically connecting the optical element array and the lead terminal has to be lowered.

  In addition, it is necessary to mount the semiconductor laser array with an array accuracy (mounting density) of several μm or less in a direction horizontal to the optical axis of the lens of the lens array, and there is a problem that the yield at the time of mounting is lowered.

  Further, in this conventional optical semiconductor module, the interval between the semiconductor laser array and the lens array becomes narrow, and it becomes difficult to store a monitor PD or the like for detecting the presence or absence of light output in the same package as the lens array. It also has problems.

  The present invention has been made to solve the above-described conventional problems, and provides an optical parallel transmission module and an optical parallel transmission system that can be stably produced by increasing the yield during mounting. The purpose is to do.

  In order to achieve the above object, one aspect of the present invention provides the following optical parallel transmission module and optical parallel transmission system.

[1] An optical element array, an optical fiber array, and a lens that is provided in common to each element of the optical element array and optically couples the optical element array and the optical fiber array. An optical parallel transmission module.

  According to the above configuration, the assembly time of the optical parallel transmission module can be shortened, the yield can be improved, and the production can be stably performed. By improving yield and productivity, it is possible to easily and reliably achieve cost reduction of the optical parallel transmission module and miniaturization of the optical connection mechanism.

[2] In the configuration described in [1] above, the optical element array is housed in a sealed container, and the lens is held in a lens barrel that fits in the sealed container. . In addition to the effect [1], the optical element array can be prevented from being deteriorated by moisture or the like.

[3] In the configuration described in [2] above, the barrel includes a positioning portion that positions a connector that holds the optical fiber array. In addition to the effect [2], the optical connection between the optical element array and the optical fiber array can be easily and reliably performed.

[4] In the configuration described in [1] above, the optical element array and the optical fiber array are held in an imaging relationship. In addition to the effect [1], the radiation angle of the light emitting element array can be reduced, the optical coupling loss can be reduced, and high light transmission efficiency can be stably obtained. It becomes like this.

[5] An optical parallel transmission system using the optical parallel transmission module according to any one of [1] to [4] as a transceiver.

  According to the above configuration, an increase in coupling loss (decrease in coupling efficiency) can be prevented, and an optical parallel transmission system in which a plurality of optical element arrays are unitized can be configured.

[6] In the configuration described in [5] above, the optical element array is a light emitting element array, the imaging relationship with respect to the optical fiber array is an enlarged optical system, and the optical element array is a light receiving element array. In other words, the image forming relationship with respect to the optical fiber array is configured as a reduction optical system. In addition to the function and effect of [5] above, the beam diameter on the light receiving surface of each element of the light receiving element array can be made smaller than the core diameter of each element in the light emitting element array. High optical coupling efficiency can be obtained even for an element having a small diameter. In addition, tolerance against misalignment can be improved.

  The present invention can provide an optical parallel transmission module and an optical parallel transmission system that can be stably produced by increasing the yield at the time of mounting.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

[First Embodiment]
(Configuration of optical parallel transmission module on transmission side)
FIG. 1 is a cross-sectional view schematically showing a configuration example of an optical parallel transmission module on the transmission side using a single lens according to the first embodiment of the present invention, and FIG. 2 is an optical parallel transmission module. FIG. 3 is a schematic view showing the optical coupling state of the optical parallel transmission module. In the first embodiment, the optical parallel transmission module on the transmission side will be described as an example. However, the present invention is not limited to this, and for example, the optical parallel transmission module on the reception side. Of course, it can be suitably used.

  In FIG. 1, reference numeral 1 denotes an optical parallel transmission module on the transmission side. As shown in FIG. 1, the basic configuration of the optical parallel transmission module 1 includes a light emitting element array 10 which is an optical element array on the transmission side, and an optical ribbon fiber array (optical fiber array) 20 including a plurality of optical fibers. And a single spherical lens 30 that optically couples the light emitting element array 10 and the optical fiber array 20.

  Further, the optical parallel transmission module 1 on the transmission side holds the can package 11 in which the light emitting element array 10 is hermetically sealed, the lens barrel 31 holding and fixing the single spherical lens 30, and the optical fiber array 20 holding and fixing. The optical fiber connector 21 is composed of three components.

  Next, the can package 11, the lens barrel 31, and the optical fiber connector 21 will be described in detail.

(Can package)
As shown in FIG. 1, the can package 11 includes a disk-shaped metal stem 12 and a light emitting element array 10 that is positioned and fixed on the metal stem 12 via a mount (not shown). In the first embodiment, a 1 × 4 VCSEL array (surface emitting semiconductor laser) with a pitch of 250 μm is used as the light emitting element array 10 (hereinafter referred to as “VCSEL array 10”). As the optical element array on the transmission side, for example, a light emitting diode (LED), an edge emitting LED, a resonator LED, an edge emitting laser diode, or the like can be used.

  A cylindrical metal cap 13 is airtightly fixed on a metal stem 12 which is one component of the can package 11 via an annular flange protruding outward. A sealed space 3 is formed inside the metal stem 12 and the metal cap 13. The sealed space 3 is sealed, for example, with an inert gas such as nitrogen gas sealed therein. In the cylindrical part of the metal cap 13, there is an opening 13 a formed concentrically with the cylindrical part of the lens barrel 31.

  A circular opening window 13b is formed at a part of the bottom of the opening 13a from the inner peripheral surface toward the center. A cover glass 15 having a disk shape is fixed to the opening window portion 13b with a low melting point glass, an epoxy resin or the like. The opening window portion 13b functions as a transmission window that transmits the laser light emitted from the VCSEL array 10.

  On the surface of the metal stem 12 opposite to the VCSEL array 10, 5 lead pins 14,... Each lead pin 14 is arranged in a state of being electrically insulated at a predetermined interval. One end of each lead pin 14 is electrically connected to the p-side or n-side electrode of the VCSEL array 10 by a bonding wire or the like. If the p-side is an individual electrode and the n-side is a common electrode as a configuration of a 1 × 4 VCSEL array, at least the number of arrays plus one external electrode is required.

  Of course, the can package 11 may be, for example, a sealed container in which a metal stem 12 and a metal cap 13 are integrally formed.

(Barrel)
As shown in FIGS. 1 and 2, the lens barrel 31 that is externally fitted and fixed to the metal cap 13 of the metal stem 12 has a cylindrical rectangular parallelepiped shape made of an insulating resin material. It is fixed to the cap 13 with an adhesive. When the lens barrel 31 is made of a metal material, it can be fixed by YAG welding.

  Inside the tube portion of the lens barrel 31, a large-diameter circular opening 31a for fitting and fixing the metal cap 13 of the metal stem 12 and a small-diameter circular opening 31b from the inner peripheral surface of the circular opening 31a toward the center are provided. It has a stepped shape. The large-diameter circular opening 31 a of the lens barrel 31 is set to a depth dimension that can adjust the positional relationship between the spherical lens 30 and the VCSEL array 10. A spherical lens 30 is held and fixed inside the small-diameter circular opening 31 b of the lens barrel 31. A pair of guide holes 31c and 31c, which are positioning portions for positioning and fixing the optical fiber connector 21, are formed in the end opening surface of the lens barrel 31 opposite to the metal stem 12. The guide hole 31c is set to a depth dimension capable of adjusting the positional relationship between the spherical lens 30 and the optical fiber connector 21.

  As shown in FIGS. 1 and 2, the spherical lens 30 is provided as a common lens with respect to each element of the VCSEL array 10, and is arranged in a state of being aligned with the axis of the metal stem 12. It is important to set the spherical lens 30 to a size that does not cause vignetting according to the pitch, the number of bits, the radiation angle, and the like of the VCSEL array 10. In the illustrated example, a single spherical lens 30 having a diameter of 4 mm and a focal length of 3 mm is used. When there is an aberration problem in the single spherical lens 30, another lens such as an aspherical lens or a compound lens system can be used in place of the single spherical lens 30.

(Optical fiber connector)
As shown in FIGS. 1 and 2, a pair of guide pins 21 a, 21 a are projected at positions corresponding to the guide holes 31 c of the lens barrel 31 on one end side of the optical fiber connector 21 attached to the lens barrel 31. Yes.

  Connected to the other end of the optical fiber connector 21 is an optical ribbon fiber 20 containing a plurality of optical fibers with a pitch of 250 μm. The optical ribbon fiber 20 is arranged so that the light emitting surface of the VCSEL array 10 is substantially in the same direction as the optical axis of the optical fiber. In the first embodiment, a plurality of optical fibers of the optical ribbon fiber 20 are exposed on the coupling surface on one end side of the optical fiber connector 21 and are held in a row at intervals of 250 μm pitch.

(Positional relationship of optical elements)
Next, the positional relationship among the optical elements of the VCSEL array 10, the optical fiber array 20, and the single spherical lens 30 will be specifically described with reference to FIG.

  FIG. 3 is a schematic diagram showing an optical coupling state of the optical parallel transmission module.

  As shown in FIG. 3, the installation position of the ball lens 30 held and fixed in the tube portion of the lens barrel 31 is the main position of the ball lens 30 from the incident end face of the optical fiber array 20 of the optical fiber connector 21 attached to the lens barrel 31. The distance (X2 + f) to the point O and the distance (X1 + f) from the VCSEL array 10 accommodated in the can package 11 to the principal point O of the spherical lens 30 are twice the focal length f of the spherical lens 30. Each distance is set (for example, 6 mm). The distance X1 between the object-side focal point of the spherical lens 30 and the VCSEL array 10 is set to the same interval dimension as the focal length f of the spherical lens 30. The distance X2 from the image-side focal point of the imaging position of the emitted light from the VCSEL array 10 to the incident end face of the optical fiber array 20 is also set to an interval dimension equal to the focal length f of the spherical lens 30. The incident end face of the optical fiber array 20 is disposed at the imaging position of the spherical lens 30.

  According to the first embodiment, the magnification m of the object and the image is configured to be m = f / X = f / f = 1 (equal magnification imaging). As a result, the pitch P1 of the VCSEL array 10 and the pitch P2 of the beam spot at the imaging position of the emitted light from the VCSEL array 10 become equal, and the emission spot diameter of the VCSEL array 10 and the output from the VCSEL array 10 The beam diameter of the beam spot at the image formation position of the incident light becomes equal. Since the incident end face of the optical fiber array 10 is arranged at the image forming position of the spherical lens 30 as described above, it is optically connected to the optical fiber array 10.

(Position adjustment of optical element)
When the optical axis of each element of the VCSEL array 10 is adjusted, active alignment is performed while monitoring the optical output of each element at the fiber end or monitoring the photocurrent of each element of the optical parallel transmission module on the receiving side. The lens barrel 31 can be fixed to the can package 11. In this case, the positional accuracy of mounting the VCSEL array 10 on the can package 11 can be relaxed to a mounting position shift of about ± 50 μm, which is an accuracy that can be realized when mounted in a general die bonding process.

  Of course, the structure, shape, and constituent members of the optical parallel transmission module 1 configured as described above are not limited to the illustrated examples.

(Effects of the first embodiment)
According to the first embodiment, the following effects can be obtained.
(A) The assembly time of the optical parallel transmission module 1 can be shortened, the yield can be improved, and the optical parallel transmission module 1 can be stably produced, and the optical parallel transmission module 1 can be reduced in cost and the optical connection mechanism can be reduced in size. be able to.
(B) The VCSEL array 10 can be prevented from deteriorating due to moisture or the like.
(C) Light connection between the VCSEL array 10 and the optical fiber array 20 can be performed easily and reliably.

[Second Embodiment]
(Configuration of optical parallel transmission module on transmission side)
FIG. 4 shows an example of the structure of the optical parallel transmission module according to the second embodiment of the present invention. 4A is a cross-sectional view schematically showing the configuration of the optical parallel transmission module on the transmission side, and FIG. 4B is a plan view schematically showing the package on the light output side of the optical parallel transmission module. 4 (c) is a cross-sectional view taken along line IVa-IVa in FIG. 4 (a).

  In these figures, the first embodiment is greatly different from the first embodiment in that it has a partially processed spherical lens 32 in which flat portions 32a and 32a perpendicular to the central axis are formed instead of the spherical lens 30. Instead of the package 11, a ceramic package 16 is provided. In these drawings, substantially the same members as those in the first embodiment are given the same member names and symbols. Therefore, the detailed description regarding these members is omitted.

  In FIG. 4, the code | symbol 32 has shown the partial process ball lens made from glass with a substantially uniform refractive index. A single partially processed ball lens 32 is held and fixed in the large-diameter opening 31b of the lens barrel 31 that is externally fitted and fixed to the ceramic package 16. Even in the second embodiment, the single partially processed spherical lens 32 can be used as a common lens for each element of the VCSEL array 10.

  As shown in FIGS. 4A to 4C, the lens barrel 31 has an elongated flat cylindrical cuboid shape made of a resin material. A pair of guide holes 31c and 31c for positioning and fixing an optical fiber connector (not shown) are formed in the end opening surface of the lens barrel 31 opposite to the ceramic package 16. In the ceramic package 16, the VCSEL array 10 is positioned and fixed via a mount (not shown). In the second embodiment, a 1 × 12 VCSEL array with a pitch of 250 μm is used. The sealed space 3 surrounded by the ceramic package 16 and the elongated cover glass 15 that transmits the laser light emitted from the VCSEL array 10 is filled with, for example, nitrogen gas.

  On the surface of the ceramic package 16 opposite to the VCSEL array 10, as shown in FIG. 4A, for example, 14 electrodes (when two common electrodes are used) for electrical connection with an external device. 17,... Are provided. Each electrode 17 is arranged in a state of being electrically insulated with a predetermined interval. One end of each electrode 17 is electrically connected to the p-side or n-side electrode of the VCSEL array 10 by a bonding wire or the like.

  As shown in FIGS. 4A to 4C, the partially processed spherical lens 32 held and fixed in the large-diameter opening 31b of the lens barrel 31 is connected to the emission end face (light emitting point) of the VCSEL array 10. It has a circular arc surface portion arranged so as to be substantially in the same direction, and flat surface portions 32a, 32a perpendicular to the central axis. Each flat portion 32 a of the partially processed spherical lens 32 is formed in a direction orthogonal to the arrangement direction of the emission end faces of the VCSEL array 10. The outer shape of the partially processed spherical lens 32 is set such that the length in the vertical direction is shorter than the horizontal direction with respect to the arrangement direction of the elements of the VCSEL array 10. It is important that the arrangement direction of the light emitting points of the VCSEL array 10 is set to a size that does not cause vignetting according to the pitch and the number of bits of the VCSEL array 10. In the second embodiment, the direction perpendicular to the arrangement direction of the light emitting points of the VCSEL array 10 can be configured so that lens vignetting for 1-bit radiation does not occur regardless of the number of bits. .

  FIG. 5 is a schematic explanatory diagram for explaining a manufacturing method of the partially processed spherical lens 32. In the figure, a rotating grinding wheel (not shown) is arranged so as to be vertically movable with respect to a machining apparatus (not shown). In producing the partially processed spherical lens 32, a part of the spherical lens is ground. In accordance with a conventional method, the spherical lens gripped by the processing device so as to be rotationally driven is rotated, and both side surfaces of the rotating spherical lens are ground by the grinding wheel in the hatched portion shown in FIG. Then, by polishing the pair of ground surfaces to a mirror surface that does not scatter light, a partially processed spherical lens 32 having a pair of plane portions 32a and 32a perpendicular to the central axis can be produced.

(Effect of the second embodiment)
According to the second embodiment, the following effects can be obtained in addition to the operational effects of the first embodiment.
(A) The optical parallel transmission module can be reduced in size and thickness.

[Third Embodiment]
(Configuration of optical parallel transmission module on transmission side)
FIG. 6 shows an example of the structure of an optical parallel transmission module according to the third embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing the configuration of the optical parallel transmission module on the transmission side. In the figure, the main difference from the above embodiments is that a monitor PD 18 for detecting the presence or absence of light input / output is housed in the can package 11. In the figure, members substantially the same as those in the above embodiments are given the same member names and symbols. Therefore, the detailed description regarding these members is omitted.

  In FIG. 6, reference numeral 18 denotes a monitor PD. Even in the third embodiment, the VCSEL array 10 that is positioned and fixed via the submount 19 is mounted on the disk-shaped metal stem 12 of the can package 11. On the metal stem 12, a cylindrical metal cap 13 is fixed in an airtight manner via an annular flange protruding outward.

  As shown in FIG. 6, the top portion of the metal cap 13 is formed concentrically with the tube portion of the lens barrel 31, and has an open window portion 13b cut obliquely across the axis. . The opening end face of the opening window portion 13b is substantially elliptical when viewed from the facing direction of the opening window portion 13b. An elliptical cover glass 15 is fixed to the opening window portion 13b with an epoxy resin or the like. The cover glass 15 is coated with a filter (not shown) having a transmittance of 50%.

  As shown in FIG. 6, a single spherical lens 30 is held and fixed in the tube portion of the lens barrel 31 that is externally fitted and fixed to the metal cap 13 of the metal stem 12. The spherical lens 30 is provided in common for each element of the VCSEL array 10. On the surface opposite to the VCSEL array 10 of the metal stem 12, there are six lead pins 14,... For electrically connecting to an external device not shown (at least one output terminal of the monitor PD is required). 14 are arranged in a state of being electrically insulated at a predetermined interval. One end of each lead pin 14 is electrically connected to the p-side or n-side electrode of the VCSEL array 10 by a bonding wire or the like.

(Effect of the third embodiment)
According to the third embodiment, in addition to the operational effects of the first embodiment, the following effects can be obtained.
(A) The distance between the VCSEL array 10 and the cover glass 15 can be set to a large size, and the reflected light from the cover glass 15 can be easily incident on the monitor PD 18.
(B) Since the top of the metal cap 13 is formed as an oblique metal cap that is cut obliquely across the axis, the amount of light incident on the monitor PD 18 can be increased.
(C) The filter coated on the cover glass 15 can increase the amount of light incident on the monitor PD 18 and can suppress the light output from the optical parallel transmission module 1 on the transmission side. As a result, the laser can be stably operated.

[Fourth Embodiment]
(Configuration of receiving side optical parallel transmission module)
FIG. 7 shows an example of the structure of an optical parallel transmission module according to the fourth embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing a configuration of a receiving side optical parallel transmission module. In the figure, the difference from the above embodiments is that an optical element array that is optically connected to a partially processed spherical lens 32 formed with a pair of plane portions 32a, 32a perpendicular to the central axis is optically parallel on the receiving side. It is in the point applied to the transmission module. In the figure, members substantially the same as those in the above embodiments are given the same member names and symbols.

  In FIG. 7, reference numeral 2 denotes an optical parallel transmission module on the receiving side. The basic configuration of the optical parallel transmission module 2 includes a photodiode (PD) array 40 that is a light receiving element array and a single partially processed spherical lens 32 that optically couples an optical fiber array of an optical fiber connector (not shown). It is comprised by. The configurations of the lens barrel 31 and the optical fiber connector in which the partially processed ball lens 32 is housed are not different from those of the above embodiments.

  In the PD package 41 on the light incident side, a photodiode (PD) array 40 is mounted via a submount 42, and a driving IC 43 is mounted. The electrodes of the PD array 40, the driving IC 43, and the PD package 41 are electrically connected by bonding wires or the like. The PD array 40 is a photoelectric conversion element that converts an electrical conversion signal in accordance with the amount of light applied to the light receiving surface based on an applied bias voltage. Incident light from the optical fiber array of the optical fiber connector is received through the optical fiber connector. The output current of the PD is input to the driving IC 43, converted into an electrical signal, and output from the plurality of electrodes 44, ..., 44 to an external device (not shown).

(Effect of the fourth embodiment)
According to the fourth embodiment, the following effects can be obtained.
(A) Since the distance between the PD array 40 and the driving IC 43 can be set short, it is possible to improve the SN ratio, improve electromagnetic radiation and immunity resistance (electromagnetic interference resistance), reduce the mounting area, and the like.

[Fifth Embodiment]
(Configuration of optical parallel transmission system)
FIG. 8 shows an example of the structure of an optical parallel transmission system using an optical parallel transmission module according to the fifth embodiment of the present invention. FIG. 8 is a schematic explanatory diagram schematically showing the configuration of the optical parallel transmission system. In the fifth embodiment, the PD package 41 of the optical parallel transmission module 2 on the reception side has the same outline as the can package 11 of the optical parallel transmission module 1 on the transmission side. In the figure, members substantially the same as those in the above embodiments are given the same member names and symbols.

  In FIG. 8, reference numeral 100 indicates an optical parallel transmission system in which the transmission side optical parallel transmission module 1 and the reception side optical parallel transmission module 2 transmit and receive signals via the optical fiber array 20.

  In this optical parallel transmission system 100, when an electrical signal is applied to the lead pin 14 of the optical parallel transmission module 1 on the transmission side, the VCSEL array 10 mounted in the can package 11 emits an optical signal and is mounted in the lens barrel 31. The light is condensed by the single spherical lens 30 and guided to the optical parallel transmission module 2 on the receiving side through the optical fiber array 20 of the optical fiber connector 21.

  On the other hand, in the PD array 40 mounted in the PD package 41, the optical signal input from the optical fiber array 20 is emitted and condensed by the single spherical lens 30 in the lens barrel 31. The signal is input to the mounted driving IC 43, converted into an electric signal, and output from the lead pin 14 to an external device (not shown).

(Positional relationship of optical elements)
Next, optical coupling between the optical parallel transmission module 1 on the transmission side and the optical parallel transmission module 2 on the reception side will be specifically described with reference to FIG.

  FIG. 9 is a schematic diagram illustrating an optical coupling state between the optical parallel transmission module 1 on the transmission side and the optical parallel transmission module 2 on the reception side. In the figure, members substantially the same as those in the above embodiments are given the same member names and symbols.

  In general, the relationship between the size of an object and an image in an imaging relationship with a lens is that the focal distance of the lens is f, the distance from the object side focal point of the lens to the object is X1, and the distance from the image side focal point to the image. If the distance is X2, the dimensional relationship of X1 × X2 = f2 is established. The magnification m between the object and the image has a dimensional relationship of m = (f / X1) = (f / X2). When the distance X1 from the object-side focal point of the lens to the object is shorter than the focal length f of the lens, the size of the image is larger than the object (m> 1, magnifying optical system). On the contrary, when the distance X1 from the object side focal point of the lens to the object is longer than the focal length f of the lens, the size of the image is smaller than the object (m <1, reduced optical). system).

  Here, in the configuration of the optical parallel transmission system, the VCSEL array can be regarded as the object side, and the PD array can be regarded as the image side. According to the fifth embodiment, as shown in FIG. 9, the optical parallel transmission system 100 forms the magnifying optical system on the VCSEL array 10 side, which is the optical element array on the transmission side, and A reduction optical system is formed on the PD array 40 side which is an optical element array. Thereby, it becomes possible to couple with the optical element arrays 10 and 40 having a pitch smaller than the pitch of the optical fiber array 20.

  According to the fifth embodiment, on the VCSEL array 10 side of the optical parallel transmission module 1 on the transmission side, the focal length f of the spherical lens 30 and the end surface of the optical fiber array 20 to the image-side focal point of the spherical lens 30. The distance X2 has a relationship of X2 = 2f as shown in FIG. The focal length f of the spherical lens 30 and the distance X1 between the object-side focal point of the spherical lens 30 and the VCSEL array 10 have a relationship of X1 = f / 2.

  In the optical parallel transmission module 1 on the transmission side, the spherical lens 30 is disposed in the lens barrel 31 so that the distance X2 from the end face of the optical fiber array 20 to the image-side focal point of the spherical lens 30 is X2 = 2f. The distance X1 from the object side focal point of the spherical lens 30 to the VCSEL array 10 is arranged in the lens barrel 31 so that X1 = f / 2. Light emitted from the VCSEL array 10 is optically imaged with the end face of the optical fiber array 20. When the calculation is performed based on the dimensional relationship of the object-image magnification m = (f / X1) = (f / X2), the magnification m at this time is m = 2. Accordingly, the VCSEL array 10 having the pitch P1 of 125 μm can be optically connected to the optical fiber array 20 having the pitch P2 of 250 μm.

  On the other hand, on the PD array 40 side of the optical parallel transmission module 2 on the reception side, as shown in FIG. 9B, the relationship is opposite to that on the VCSEL array 10 side, and the focal length f of the spherical lens 30 is The distance X1 from the object side focal point of the spherical lens 30 to the PD array 40 has a relationship of X1 = 2f. The focal length f of the spherical lens 30 and the distance X2 from the image-side focal point of the spherical lens 30 to the light receiving surface of the PD array 40 have a relationship of X2 = f / 2.

  In the optical parallel transmission module 2 on the reception side, the spherical lens 30 is disposed in the lens barrel 31 so that the distance X1 from the object-side focal point of the spherical lens 30 to the PD array 40 is X1 = 2f. A distance X2 from the image side focal point of the spherical lens 30 to the light receiving surface of the PD array 40 is arranged in the lens barrel 31 so that X2 = f / 2. Thereby, the emitted light from the optical fiber array 20 is imaged on the light receiving surface of the PD array 40. If the magnification m of the object and the image is calculated based on the dimensional relationship of m = (f / X1) = (f / X2), the magnification m at this time is m = 0.5, and thus the optical fiber having a pitch P2 of 250 μm. The array 20 can be optically connected to a PD array 40 having a pitch P1 of 125 μm.

  According to the above configuration, the beam diameter (core diameter) and radiation angle at the end face of the optical fiber array 20 with respect to the 1-bit emission spot diameter and radiation angle of the VCSEL array 10 are doubled and 0.5 times, respectively. . The beam diameter on the light receiving surface of the PD array 40 is 0.5 times the beam diameter on the end surface of the optical fiber array 20.

  By the way, in optical parallel transmission, a GI multimode fiber having a core diameter of 50 μm and NA (numerical aperture) = 0.2 (maximum light receiving angle θ = 11.6 °) is generally used. The 1-bit emission spot diameter of the VCSEL array 10 is 5 to 20 μm, and the radiation angle is 10 to 30 ° in all angles. According to the optical parallel transmission system 100 according to the fifth embodiment, on the incident end face of the optical fiber array 20, the beam diameter is 10 to 40 μm, the incident angle is 5 to 15 °, and the coupling loss due to the NA mismatch is reduced. Can be improved. If the magnification m is increased too much, coupling loss due to the difference in beam diameter will increase, and therefore it is preferable that the magnification m satisfies m = 1-2.

  The light receiving diameter of the PD array used for a transmission speed of 1 Gbps or more is 40 to 100 μm, and the beam diameter at the light receiving surface of the PD array is 1 of the beam diameter (core diameter) at the emission end face of the optical fiber array. / 2 (25 μm), the optical parallel transmission system 100 according to the fifth embodiment can improve the optical coupling efficiency or the tolerance for misalignment. On the PD array 40 side, setting the magnification to be small is desirable in terms of improving the optical coupling efficiency and misalignment tolerance. However, to set the magnification small, the optical system, that is, the module size becomes large. As the magnification m, it is preferable to satisfy m = 0.5-1.

  In the optical parallel transmission system 100 according to the fifth embodiment, the imaging relationship with respect to the optical fiber array 20 on the transmission side can be formed in the magnifying optical system. The lateral magnification (image height) of the magnifying optical system is preferably 1 to 2. The imaging relationship with respect to the optical fiber array 20 on the receiving side can be formed in the reduction optical system. It is preferable to satisfy 0.5 to 1 as the lateral magnification (image height) of the reduction optical system.

(Effect of 5th Embodiment)
According to the fifth embodiment, the following effects can be obtained.
(A) By reducing the pitch, the material cost and the processing cost can be reduced, and the optical element arrays 10 and 40 having a small chip size can be used.
(B) An optical parallel transmission system in which a plurality of optical element arrays 10 and 40 are unitized can be obtained by the optical parallel transmission module 100 capable of preventing an increase in coupling loss (decrease in coupling efficiency). it can.

  The optical parallel transmission module and the optical parallel transmission system according to the present invention are not limited to the above embodiments and modifications, and various design changes can be made without departing from the spirit of the invention. is there.

  The optical parallel transmission module and the optical parallel transmission system according to the present invention are used for various optical communication devices and optical communication systems such as short-distance optical communication such as home network and LAN, large and medium-distance optical communication, and high-speed communication (gigabit). be able to.

It is sectional drawing which shows roughly the example of 1 structure of the optical parallel transmission module of the transmission side using the single lens which is the 1st Embodiment of this invention. It is a top view which shows roughly the package by the side of the light emission of an optical parallel transmission module. It is a schematic diagram which shows the optical coupling state of an optical parallel transmission module. (A) is sectional drawing which shows schematically the structure of the optical parallel transmission module of the transmission side which is the 2nd Embodiment of this invention, (b) is schematic about the package by the side of the light emission of an optical parallel transmission module. FIG. 4C is a sectional view taken along the line IVa-IVa in FIG. 4A. FIG. 5 is a schematic explanatory diagram for explaining a method of manufacturing a partially processed ball lens 32. It is sectional drawing which shows roughly the structure of the optical parallel transmission module of the transmission side which is the 3rd Embodiment of this invention. It is sectional drawing which shows schematically the structure of the optical parallel transmission module of the receiving side which is the 4th Embodiment of this invention. It is a schematic explanatory drawing which shows roughly the structure of the optical parallel transmission system which is the 5th Embodiment of this invention. (A), (b) is a schematic diagram which respectively shows the optical coupling state of the optical parallel transmission module 1 of the transmission side shown in FIG. 8, and the optical parallel transmission module 2 of the reception side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical parallel transmission module 2 of transmission side Optical parallel transmission module 3 of reception side Sealed space 10 VCSEL array 11 Can package 12 Metal stem 13 Metal cap 13a Opening part 13b Opening window part 14 Lead pin 15 Cover glass 16 Ceramic package 17, 44 Electrode 18 Monitor PD
19, 42 Submount 20 Optical fiber array 21 Optical fiber connector 21a Guide pin 30 Ball lens 31 Lens barrel 31a, 31b Circular opening 31c Guide hole 32 Partially processed ball lens 32a Planar part 40 PD array 41 PD package 43 Driving IC
100 Optical parallel transmission system

Claims (6)

An optical element array;
An optical fiber array;
An optical parallel transmission module comprising a lens provided in common to each element of the optical element array and optically coupling the optical element array and the optical fiber array. The optical element array is housed in a sealed container,
The optical parallel transmission module according to claim 1, wherein the lens is held in a lens barrel that fits into the sealed container.   The optical parallel transmission module according to claim 2, wherein the lens barrel includes a positioning portion that positions a connector that holds the optical fiber array.   The optical parallel transmission module according to claim 1, wherein the optical element array and the optical fiber array are held so as to form an imaging relationship.   An optical parallel transmission system using the optical parallel transmission module according to any one of claims 1 to 4 as a transceiver. The optical element array is a light emitting element array, and has a configuration in which an imaging relationship with the optical fiber array is an enlarged optical system,
The optical parallel transmission system according to claim 5, wherein the optical element array is a light receiving element array, and has a configuration in which an imaging relationship with the optical fiber array is a reduction optical system.

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