Optical engine and optical module

An optical engine includes a substrate provided with terminals configured to connect to a connector provided on another substrate, a light receiver/emitter mounted on the substrate, and a cover covering the substrate. The light receiver/emitter is any one of a light receiver, a light emitter, and an element having functions of both the light receiver and the light emitter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims priority to Japanese Patent Application No. 2017-211517 filed on Nov. 1, 2017, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The embodiments discussed herein are related to an optical engine and an optical module.

2. Description of the Related Art

Supercomputers, high-end servers, or the like may employ high-speed interfaces that perform optical communication. The optical communication can cope with high-speed transmission of signals, and extend a transmission distance of the signals.

In a next-generation interface that performs the optical communication and has a relatively long transmission distance of several tens of meters, for example, an optical module is used to connect an optical cable and a sever, to perform a conversion between electrical signals and optical signals. The optical module converts the optical signals into the electrical signals, and converts the electrical signals into the optical signals.

The optical module is formed by an optical engine that includes a light emitter, a light receiver, a driver IC (Integrated Circuit) that drives the light emitter, and a TIA (Trans Impedance Amplifier) that converts a current into a voltage. The optical module may be provided on a mother board of an information processing apparatus, such as the supercomputer or the like. Examples of prior art may include Japanese Laid-Open Patent Publication No. 2011-128378, Japanese Laid-Open Patent Publication No. 2012-181442, and International Publication Pamphlet No. WO2013/046416.

When the optical module is provided on the mother board, multiple optical engines may be used. However, because the size of the mother board is limited, there are demands to mount the optical engine on the mother board at a high density and with a high reliability.

SUMMARY OF THE INVENTION

Accordingly, it is an object in one aspect of the embodiments to provide an optical engine and an optical module, which can mount the optical engine on a mother board of an information processing apparatus at a high density and with a high reliability.

According to one aspect of embodiments of the present invention, an optical engine includes a substrate provided with terminals configured to connect to a connector provided on another substrate, a light receiver/emitter mounted on the substrate, and a cover covering the substrate, wherein the light receiver/emitter is any one of a light receiver, a light emitter, and an element having functions of both the light receiver and the light emitter.

According to another aspect of the embodiments of the present invention, an optical module includes a first substrate provided with connectors, and an optical engine, the optical engine includes a second flexible substrate that is provided with terminals electrically connected to the one of the connectors, a light receiver/emitter mounted on the second substrate, and a cover covering the second substrate, wherein the light receiver/emitter is any one of a light receiver, a light emitter, and an element having functions of both the light receiver and the light emitter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of an optical engine and an optical module according to the present invention will be described, by referring to the drawings. In the drawings, those parts or members that are the same are designated by the same reference numerals, and a description of the same parts or members may be omitted.

First Embodiment

An optical engine in a first embodiment will be described.FIG. 1is a diagram illustrating the optical engine in one embodiment. As illustrated inFIG. 1, a light emitter21, a light receiver22, a driver IC23, and a TIA24are provided on a first surface of a flexible substrate10. The flexible substrate10may be a so-called FPC (Flexible Printed Circuit) having a structure in which insulator films made of polyimide or the like are laminated from above and below wirings. In addition, an optical waveguide30is connected to a second surface of the FPC10, opposite to the first surface. For example, the first surface of the FPC10is a top surface, and the second surface of the FPC10is a bottom surface illustrated inFIG. 1. One end of the optical waveguide30, opposite to the end connected to the FPC10, is connected to an optical connector40.

In this embodiment, the FPC10has a thickness greater than or equal to 50 μm and less than or equal to 150 μm. In this example, the FPC10has a thickness of 60 μm. Terminals11that connect to a FPC connector120or121that will be described later and is not illustrated inFIG. 1are provided on a surface of the FPC10.

The light emitter21may be a VCSEL (Vertical Cavity Surface Emitting Laser) or the like that converts an electrical signal into an optical signal and emit light. The light receiver22may be a photodiode or the like that converts an optical signal into an electrical signal and outputs the electrical signal.

In this specification, a “light receiver/emitter” refers to an element that has a function of at least one of receiving light or emitting light. Hence, the “light receiver/emitter” may be any one of a light receiver, a light emitter, and an element having functions of both the light receiver and the light emitter.

The optical waveguide30may be formed by a flexible sheet, and include a clad formed around a plurality of cores, such that light incident to the optical waveguide30propagates through the cores. The optical connector40includes a ferrule with a lens and a MT (Mechanical Transfer) ferrule that are connected and fixed to each other by a clip, for example.

In the optical engine, light incident to the optical connector40propagates through the cores within the optical waveguide30, and reaches the light receiver22mounted on the FPC10. An output current of the light receiver22changes according to the light received by the light receiver22. The TIA24converts the output current of the light receiver22into a voltage, to convert the current change into a voltage change. An output of the TIA24may be used as an electrical signal inside the information processing apparatus. In addition, the electrical signal inside the information processing apparatus is converted into an optical signal by the light emitter21. The light emitter21emits light towards the optical waveguide30, and the light propagates through the cores of the optical waveguide30to output an optical signal from the optical connector40.

An optical module in this embodiment uses multiple optical engines. Because the thickness of the FPC10is extremely thin compared to a general PCB (Printed Circuit Board), the optical engines can be mounted at a high density. However, as the FPC10is extremely thin, the FPC10may easily bend or warp. Consequently, in a case in which the optical engines are mounted at a high density, mutually adjacent optical engines may contact each other, or a conductance of the FPC10may change due to the bending or warping of the FPC10, to affect the electrical signal.

For this reason, in this embodiment, a cover51and a cover52are provided to sandwich the FPC10from both sides, as illustrated inFIG. 2AandFIG. 2B.FIG. 2Ais a plan view of the optical engine100covered by the cover51and the cover52.FIG. 2Bis a cross sectional view cut along a one-dot chain line2A-2B inFIG. 2B. The cover51and the cover52are made of an insulator, such as a resin material or the like, and respectively have a thickness of approximately 1 mm. The optical waveguide30has a thickness of approximately 100 μm, and the driver IC23and the TIA24respectively have a thickness of approximately 250 μm. The first surface of the FPC10, mounted with the driver IC23and the TIA24, is entirely covered by the cover51. The second surface of the FPC10, to which the optical waveguide30is connected, is covered by the cover52.

In this embodiment, the cover51and the cover52are fixed by a pin60as illustrated inFIG. 3.FIG. 3is a cross sectional view cut along a one-dot chain line2C-2D inFIG. 2A. The pin60is inserted from a hole51aprovided in the cover51towards a hole52aprovided in the cover52. The hole51aand the hole52arespectively have a diameter of approximately 1 mm. The diameter of each of the hole51aand52ais slightly smaller than a diameter of the pin60, so that the pin60is interfitted into the hole51aand the hole52ato fix the cover51and the cover52to each other. A tip end60aof the pin60is tapered so that the tip end60aeasily enters the hole51aand the hole52a. In this embodiment, a the tip end60aof the pin60penetrates the FPC10between the hole51aand the hole52a. As a result, the FPC10, the cover51, and the cover52are fixed together by the pin60.

As described above, the terminals11are provided on the first surface of the FPC10, to form pads of the FPC to be connected to the connector120or121that will be described later. The pin60is provided at positions illustrated inFIG. 2A, in order to fix the cover51and the cover52to the FPC10at both ends on the outer sides of the terminals11, so as to prevent a positional error, or bending or warping of the FPC at these positions.

The optical module in this embodiment may be provided with projections on one of the two covers, corresponding to the openings in the other of the two covers. In an example illustrated inFIG. 4, a projection51bcorresponding to the opening52ain the cover52is provided on the cover51. In this case, the cover51and the cover52may be fixed to each other by interfitting the projection51binto the opening52a.

Next, the optical module in this embodiment will be described, by referring toFIG. 5andFIG. 6.FIG. 5is a diagram illustrating the optical module in the first embodiment, andFIG. 6is a disassembled perspective view of the optical module in the first embodiment.

An optical module200in this embodiment is mounted with multiple optical engines100. The optical module200includes a wiring board110, the FPC connector120, and heat dissipation members131and132. The wiring board110may be a PCB, and FPC connectors120may be arranged at predetermined intervals on a surface110aof the wiring board110. The optical engines100may be connected to the FPC connectors120by inserting the terminals11of each FPC10into a corresponding FPC connector120. In the example illustrated inFIG. 5andFIG. 6, in order to mount the optical engines100at the high density, the FPC connectors120are provided on the wiring board110so that the surface of the FPC10may be set approximately perpendicular to the surface110aof the wiring board110.

In the optical engine100, the FPC10is sandwiched between the cover51and the cover52that are thicker than the FPC10and are uneasily bent or warped. For this reason, even when a force is applied to the optical engine100when mounting the optical engine100or after the optical engine100is mounted, the FPC10can be prevented from bending or warping.

The cover51and the cover52made of insulator cover the light emitter21, the light receiver22, the driver IC23, and the TIA24that are provided in the optical engine100. For this reason, even in a case in which the optical engines100are mounted at the high density in the optical module200, it is possible to prevent terminals of the light emitter21, the light receiver22, the driver IC23, and the TIA24that are provided in the mutually adjacent optical engines100from contacting each other.

In this embodiment, a rectangular tube-shaped heat dissipation member131is provided to surround peripheries of the optical engines100mounted on the FPC connectors120. In addition, a plate-shaped heat dissipation member132is provided on the heat dissipation member131to cover the optical engines100. The heat dissipation member131opposes a sidewall of each of the optical engines100. On the other hand, the heat dissipation member132opposes a top surface of each of the optical engines100.

The optical module200described above is connected to a wiring board170that forms a mother board, via a socket160that converts a pitch of the terminals.

The optical module200may include the optical engines100that are arranged obliquely with respect to the surface110aof the wiring board110, as illustrated inFIG. 7. In this case, the FPC connectors121are mounted obliquely with respect to the surface110a, so as to mount the optical engines100obliquely with respect to the surface110a. When the optical engine100is mounted obliquely with respect to the surface110a, it becomes easier to connect and disconnect the optical engine100with respect to the FPC connector121. In addition, an overall height of the optical module200can be reduced.

<Connection of Optical Engine>

Next, a description will be given of the connection of the optical engine100to the FPC connector120.

FIG. 8Ais a bottom view of the optical engine100, andFIG. 8Bis a cross sectional view cut along a one-dot chain line2E-2F inFIG. 2A.FIG. 9is a diagram illustrating the optical engine100connected to the FPC connector120, in a state in which the cover51is removed and the FPC connector120is cut along a plane parallel to the FPC10.

In this embodiment, a first protrusion53and a second protrusion54that extend from the flexible substrate10towards the FPC connector120are provided on the cover51and the cover52. Corresponding parts of the covers51and52form the first protrusion, and corresponding parts of the covers51and52form the second protrusion54. As illustrated inFIG. 9, the first protrusion53and the second protrusion54respectively fit into a first cavity and a second cavity famed in the FPC connector120. The first protrusion53and the second protrusion54are formed in the state in which the cover51and the cover52are connected to each other, and in this state, the terminals11are positioned between the first protrusion53and the second protrusion54.

As illustrated inFIG. 8A, the first protrusion53is provided on the left side of the terminals11, and the second protrusion54is provided on the right side of the terminals11. The first protrusion53and the second protrusion54have mutually different shapes, and the second protrusion54is thicker than the first protrusion53. The first cavity provided in the FPC connector120has a shape corresponding to the shape of the first protrusion53, and the second cavity provided in the FPC connector120has a shape corresponding to the shape of the second protrusion54. By forming the first protrusion53and the second protrusion54to mutually different shapes, it is possible to prevent the optical engine100from being erroneously inserted into the FPC connector120in an incorrect direction or facing an incorrect direction.

In addition, the first protrusion53includes a tapered part53athat is tapered inward toward the FPC connector120, and the second protrusion54includes a tapered part54athat is tapered inward toward the FPC connector120. The tapered part53aand the tapered part54afacilitate insertion of the optical engine100into the FPC connector120.

As illustrated inFIG. 8AandFIG. 8B, an opening55is formed at parts of the cover51and the cover52where the terminals11are provided. The FPC connector120enters the opening55to connect the terminals11to the FPC connector120as illustrated inFIG. 9.

In addition, as illustrated inFIG. 8AandFIG. 8B, the opening55has an inverted trapezoidal shape. A side55aof the opening55at the cover51is longer than a side55bof the opening55at the cover52. The FPC connector120has a shape corresponding to the shape of the opening55. Because the opening has the inverted trapezoidal shape, it is possible to prevent the optical engine100from being erroneously inserted into the FPC connector120in an incorrect direction. Hence, a combination of the shapes of the first and second protrusions53and54and the first and second cavities, and a combination of the shapes of the opening55and the FPC connector120, provide a double prevention mechanism for preventing the optical engine100from being erroneously inserted into the FPC connector120in the incorrect direction or facing the incorrect direction.

Second Embodiment

Next, a second embodiment will be described. In this embodiment, flanges are provided on the covers of the optical engine, and hooks for fixing the flanges are provided on the FPC connector.

A description will be given of the optical engine and the FPC connector in this embodiment, by referring toFIG. 10. An optical engine300in this embodiment includes a cover351and the other cover (not illustrated) that are mounted on both sides of the FPC10. Although only the cover351is illustrated inFIG. 10at the paper top surface end, the other cover is provided at the paper bottom surface end. The FPC10is sandwiched and fixed between the cover351and the other cover.

A first flange355and a second flange356that extend from the FPC10in a direction perpendicular to a direction in which the optical engine300is inserted into a FPC connector320are provided on the cover351and the other cover. Corresponding parts of the cover351and the other cover form the first flange355, and corresponding parts of the cover351and the other cover form the second flange356.

The FPC connector320includes a main body321, a first hook325corresponding to the first flange355, and a second hook326corresponding to the second flange356. The first hook325is mounted on the main body321in a state rotatable about a rotational shaft325aas its center of rotation, and the second hook326is mounted on the main body321in a state rotatable about a rotational shaft326aas its center of rotation.

When mounting the optical engine300on the FPC connector320, the side of the optical engine300provided with the terminals11is inserted into the FPC connector320, from the state illustrated inFIG. 10to the state illustrated inFIG. 11. Hence, the first flange355and the second flange356contact an upper part of the main body321.

Thereafter, as illustrated inFIG. 12, the first hook325is rotated clockwise by approximately 90° about the rotational shaft325a, to cover and fix the first flange355by the first hook325. Similarly, the second hook326is rotated counterclockwise by approximately 90° about the rotational shaft326a, to cover and fix the second flange356by the second hook326. Because the first and second flanges355and366are respectively fixed by the first and second hooks325and326, it is possible to prevent the optical engine300from slipping off from the FPC connector320.

The features and effects of the second embodiment are otherwise similar to the features and effects of the first embodiment described above.

Third Embodiment

Next, a third embodiment will be described. In an optical module in this embodiment, a resin material fills the inside of the region surrounded by the wiring board110, the FPC connectors120, and the heat dissipation members131and132. A manufacturing process of the optical module in this embodiment will be described, by referring toFIG. 13,FIG. 14, andFIG. 15.

First, as illustrated inFIG. 13, the optical engine100is connected to each FPC connector120, and the heat dissipation member131is provided to cover the optical engines100mounted on the FPC connectors120.

Next, as illustrated inFIG. 14, a resin material180is filled into an inner side of the heat dissipation member131and cured. Hence, each of the optical engines100is fixed. The resin material180may be a silicon resin or the like, for example. In this embodiment, as the cover51and the cover52are mounted on the optical engine100, the optical engine100will not bent or warped by the resin material180that flows into the inner side of the heat dissipation member131.

If the covers51and52were not provided on the optical engine100, the flexible substrate may be pushed and bent by the flow of the resin material180entering the inner side of the heat dissipation member131as the flexible substrate is extremely thin, and may cause inconveniences such as a change in the conductivity of the wirings of the flexible substrate, or contact between the mutually adjacent optical engines100. However, according to this embodiment, the optical engine100is provided with the cover51and the cover52, and the optical engine100will not be bent by the flow of the resin material180, and the above described inconveniences will not occur.

Next, as illustrated inFIG. 15, the plate-shaped heat dissipation member132is mounted on the cured resin material180. An upper surface of the heat dissipation member131and the heat dissipation member132are bounded by an adhesive agent or the like.

The optical module in this embodiment includes the resin material180that fills the peripheries of the optical engines100that are connected to the FPC connectors120, to prevent the optical engine100from slipping off the FPC connector120, and prevent the optical engine100from moving.

In this embodiment, the resin material180is preferably an insulator, and from a heat dissipation viewpoint, is more preferably a resin material having a high thermal conductivity.

Fourth Embodiment

Next, the optical module in a fourth embodiment will be described. The optical module in this embodiment has a structure having improved heat dissipation. When the optical engine100is driven, elements such as the driver IC23and the TIA24generate heat, and efficient dissipation of such heat is desirable.

As illustrated inFIG. 16, the optical module in this embodiment including a heat dissipation member430and a heat dissipation member440, in order to efficiently dissipate the heat generated from the driver IC23and the TIA24that are provided on each of the optical engines100. The heat dissipation member430and the heat dissipation member440are made of a material having a high thermal conductivity, such as metal, aluminum or the like, for example. However, the heat dissipation member430and the heat dissipation member440may be made of a resin or the like as long as a sufficient heat dissipation effect is obtainable by the material used.

The heat dissipation member430includes an upper plate431corresponding to the heat dissipation member132, and heat dissipation plates432extending from a surface431aof the upper plate431in a direction in which the optical engine100connects to the FPC connector120. The heat dissipation member440has an L-shape, and includes a connection part441mounted on the surface431a, and a heat dissipation plate442connected approximately perpendicularly to the connection part441. In this embodiment, the connection part441is mounted on the surface431aby a screw450.

In this embodiment, the optical engine100mounted with the cover51and the cover52is sandwiched between the heat dissipation plate432and the heat dissipation plate442. The heat generated from elements of the optical engine100such as the driver IC23and the TIA24is transferred to the heat dissipation plates432and442via the cover51and the cover52, respectively, and is further transferred to the upper plate431, to be released from a surface431b.

Next, a method of mounting the heat dissipation members430and440in the optical module will be described, by referring toFIG. 17AthroughFIG. 18B. In this embodiment, after the optical engine100is mounted on each FPC connector120, the heat dissipation member430is arranged to cover the optical engines100and the FPC connectors120, to make the cover51contact the heat dissipation plate432as illustrated inFIG. 17B.FIG. 17Ais a top view in this state, andFIG. 17Bis an internal side view in this state.

An elongated hole431cfor mounting the heat dissipation member440is provided in the upper plate431, and the heat dissipation member440is mounted on the surface431aby the screw450that is inserted through the elongated hole431c. The heat dissipation member440mounted on the surface431aby the screw450is movable in the right and left directions inFIG. 17AandFIG. 17B.

Thereafter, the heat dissipation member440is moved in the right direction as illustrated inFIG. 18AandFIG. 18B, to make the cover52contact the heat dissipation plate442, and the screw450is fastened at this position to fix the heat dissipation member440. Hence, the optical engine100is fixed in the state sandwiched between the heat dissipation plate432and the heat dissipation plate442, and the heat generated from the driver IC23or the TIA24can be efficiently dissipated from the heat dissipation plates432and442that are in contact with the covers51and52, respectively.

For example, the heat is not smoothly dissipated when gaps are formed between the optical engine100and the heat dissipation plate432and the heat dissipation plate442. However, in this embodiment, the heat dissipation member440can be moved with respect to the heat dissipation member430, so that the cover51and the heat dissipation plate432more positively make contact and the cover52and the heat dissipation plate442more positively make contact. As a result, it is possible to efficiently dissipate the heat generated from the driver IC23, the TIA24, or the like.

The optical module in this embodiment may have a heat dissipation plate461and a heat dissipation plate462that are mounted on a heat dissipation member460by a screw451as illustrated inFIG. 19throughFIG. 21, so that both the heat dissipation plate461and the heat dissipation plate462are movable.FIG. 19is a cross sectional view,FIG. 20is an enlarged view, andFIG. 21is a top view of the optical module.FIG. 21illustrates a state in which the heat dissipation plates461and462on the right side of this figure are fasted by the screw451.

As illustrated inFIG. 21, a screw hole460ais formed in the heat dissipation member460. In addition, as illustrated inFIG. 20, upper parts of the heat dissipation plates461and462are bent to an L-shape. An elongated opening461acorresponding to the screw hole460ais provided in the bent upper part of the heat dissipation plate461. Similarly, an elongated opening462acorresponding to the screw hole460ais provided in the bent upper part of the heat dissipation plate462. When fastening the heat dissipation plates461and462on the heat dissipation member460, the heat dissipation plates461and462may be moved in the horizontal direction along the respective openings461aand462a.

In this embodiment, the heat dissipation plate461is made to contact the cover51, and the heat dissipation plate462is made to contact the cover52. In this state, the heat dissipation plate461and the heat dissipation plate462are fixed to the heat dissipation member460by fastening the screw451. Because both the heat dissipation plates461and462are movable in the horizontal direction by amounts corresponding to the respective lengths of the openings461aand462a, the heat dissipation plates461and462can more positively contact the optical engine, even in a case in which the optical engines having different widths are used. In addition, it is easier to adjust the positions of the heat dissipation plates461and462because both the heat dissipation plates461and462are movable.

Accordingly, the heat generated from the element such as the driver IC23and the TIA24is transferred to the heat dissipation plates461and the heat dissipation plates462via the cover51and the cover52, respectively, and is further transferred to the heat dissipation member460to be released from the heat dissipation member460.

The features and effects of the fourth embodiment are otherwise similar to the features and effects of the first embodiment described above.

According to the embodiments described above, it is possible to mount the optical engine on the mother board at a high density and with a high reliability.

Although the embodiments are numbered with, for example, “first,” “second,” “third,” etc., the ordinal numbers do not imply priorities of the embodiments.