OPTICAL TRANSCEIVER SYSTEM AND LASER DIODE DEVICE THEREOF

An optical transceiver system includes a laser diode device. The laser diode device includes a first submount, a second submount, a laser diode, and a bump. The first submount includes a first electrode. The second submount corresponds to the first submount and includes a second electrode. The laser diode is between the first submount and the second submount, and a side of the laser diode adjacent to the first submount is electrically connected to the first electrode. The laser diode has a waveguide and the waveguide is on a side of the laser diode away from the first submount. The bump corresponds to the waveguide, one of two ends of the bump is electrically connected to the second electrode, and a height of the bump is substantially higher than a height of the waveguide.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. § 119 (a) to patent application No. 112119209 filed in Taiwan, R.O.C. on May 23, 2023, and the entire contents of which are hereby incorporated by reference.

BACKGROUND

Technical Field

The instant disclosure relates to an optical transceiver system and a laser diode device thereof, particularly a laser diode device having a waveguide and an optical transceiver system comprising the laser diode device.

Related Art

Along with the increasingly improved speed of communication, demands for laser diodes with their luminous efficacy being suitable for applying to high-speed optical communication products are also increased. Compared with existing laser diodes applied to low-speed optical communication products, power of laser diodes applied to high-speed optical communication products is relatively higher, and the heat generated by the laser diodes is also increased. Moreover, on certain demands, some laser diodes have to be driven at a relatively lower temperature.

SUMMARY

In view of this, according to some embodiments, a laser diode device is provided, and the laser diode device comprises a first submount, a second submount, a laser diode, and a bump. The first submount comprises a first electrode. The second submount corresponds to the first submount and the second submount comprises a second electrode. The laser diode is between the first submount and the second submount, and a side of the laser diode adjacent to the first submount is electrically connected to the first electrode. The laser diode has a waveguide and the waveguide is on a side of the laser diode away from the first submount. The bump corresponds to the waveguide and one of two ends of the bump is electrically connected to the second electrode, wherein a height of the bump is substantially higher than a height of the waveguide.

According to some embodiments, the other end of the bump is electrically connected to the laser diode to allow the bump to be electrically connected to the first electrode through the side of the laser diode adjacent to the first submount.

According to some embodiments, the bump is a stud bump, the stud bump has a first diameter at a side of the stud bump adjacent to the laser diode, the stud bump has a second diameter at a side of the stud bump adjacent to the second submount, and a ratio of the first diameter over the second diameter is between 0.9 and 1.1.

According to some embodiments, the bump is a stud bump, the stud bump has a first diameter at a side of the stud bump adjacent to the laser diode, the stud bump has the height extending from the laser diode toward the second submount, and a ratio of the first diameter over the height of the stud bump is between 0.85 and 1.1.

According to some embodiments, a receiving space is between the first submount, the laser diode, and the second submount. The receiving space is filled with a filling material, wherein the filling material comprises an insulating base and a plurality of conductive particles, the conductive particles are distributed over the insulating base, and parts of the conductive particles are between the bump and the second submount.

According to some embodiments, the bump is a second submount protrusion, and the second submount protrusion extends from the second submount to allow the laser diode to be electrically connected to the second electrode through the second submount protrusion.

According to some embodiments, the bump is a conductive paste on a side of the laser diode adjacent to the second submount.

In addition, according to some embodiments, an optical transceiver system is further provided, and the optical transceiver system comprises an optical fiber, a lens, and the laser diode device. The lens is adjacent to the optical fiber. The laser diode of the laser diode device is communicatively connected to the lens and the optical fiber through a light source.

According to some embodiments, the optical transceiver system further comprises a laser diode driver electrically connected to the laser diode device, wherein the laser diode driver emits a driving signal to the laser diode device to allow the laser diode of the laser diode device to be communicatively connected to the lens and the optical fiber through the light source.

DETAILED DESCRIPTION

Please refer toFIG.1A,FIG.1B,FIG.2A, andFIG.2B.FIG.1Aillustrates a schematic perspective view of an uncovered laser diode device1aaccording to some embodiments;FIG.1Billustrates a schematic cross-sectional view along the line A-A′ of the uncovered laser diode device1ashown inFIG.1A;FIG.2Aillustrates a schematic perspective view of a covered laser diode device1bin a first view according to some embodiments; andFIG.2Billustrates a schematic perspective view of the covered laser diode device1bshown inFIG.2Ain a second view. To more clearly illustrate the embodiments, the uncovered laser diode devices1ashown inFIG.1AandFIG.1Bare basically identical to the covered laser diode device1bshown inFIG.2AandFIG.2B, and the difference between the uncovered laser diode device1aand the covered laser diode device1bis that, inFIG.1AandFIG.1B, only a first submount11and a laser diode10of the laser diode device1aare illustrated (which will be referred to as the “uncovered” laser diode device1aherein); while inFIG.2AandFIG.2B, in addition to the first submount11and the laser diode10, a second submount12and a bump14(the bump14may be referred to inFIG.3A, which will be described later) of the laser diode device1bare further illustrated (which will be referred to as the “covered” laser diode device1bherein). It is noted that if not particularly annotated by the term “uncovered,” the term “laser diode device1b” used herein indicates “the covered laser diode device1b.”

InFIG.1A,FIG.1B,FIG.2A, andFIG.2B, the laser diode device1bcomprises a first submount11, a second submount12(shown inFIG.2AandFIG.2B), a laser diode10, and a bump14. The first submount11comprises a first electrode116(shown inFIG.2B, which may be a ball of wire bonding). The second submount12corresponds to the first submount11and the second submount12comprises a second electrode128(shown inFIG.2AandFIG.2B, which may be a ball of wire bonding). The laser diode10is between the first submount11and the second submount12(shown inFIG.2AandFIG.2B), and a side of the laser diode10adjacent to the first submount11is electrically connected to the first electrode116. The laser diode10has a waveguide102on the laser diode10(e.g., on a side of the laser diode10away from the first submount11). The waveguide102may be an optical waveguide to guide visible light and/or other electromagnetic waves (which will be described later). The bump14corresponds to the waveguide102(e.g., the bump14is adjacent to the waveguide102and on a side of the laser diode10away from the first submount11). One of two ends of the bump14is electrically connected to the second electrode128(which will be described later). A height H1of the bump14is substantially higher than a height H2of the waveguide102(shown inFIG.3AandFIG.4, which will be described later). The material of the bump14may be an electrically and/or thermally conductive material to allow the surface heat generated by the laser diode10(e.g., the surface heat on the side of the laser diode10adjacent to the waveguide102) to be guided away from the laser diode10, thereby rapidly reducing the surface temperature of the laser diode10. Meanwhile, the bump14may be electrically connected to the second electrode128to receive the current from the second electrode128and guide the current to the laser diode10, so that the laser diode10may be further driven by the current. Moreover, through the arrangement that the height H1of the bump14is substantially higher than the height H2of the waveguide102, the waveguide102can be prevented from being directly contacted and further damaged by the second submount12. Hence, in some embodiments, the waveguide102can be effectively prevented from being damaged by the cover of the second submount12(and/or being squeezed by the second submount12cause by the thermal expansion of the second submount12) which will further affect the luminous efficacy of the waveguide102, so that the surface cooling performance of the laser diode10can be enhanced effectively at the same time.

In some embodiments, the laser diode10may be any laser diode having the structure of the waveguide102; for example, the laser diode10may be but not limited to a distributed feedback (DFB) laser, an electro-absorption modulated laser (EML), a Fabry-Perot (FP) laser, a distributed Bragg reflector (DBR), a quantum dot (QD) laser, or any combination thereof. In other words, the laser diode10may be at least one selected from the group consisting of a distributed feedback (DFB) laser, an electro-absorption modulated laser (EML), a Fabry-Perot (FP) laser, a distributed Bragg reflector (DBR), and a quantum dot (QD) laser. Therefore, the laser diode10also comprises a combination of two or even more than two selected from the above group. Hence, through the laser diode10having the characteristics of high output power and fast modulation speed, the laser diode device1bcan be applied to the high-speed optical communication, such as medium-distance and long-distance high-speed broadband telecommunications transmission.

Please refer toFIG.1BandFIG.3A.FIG.3Aillustrates a schematic cross-sectional view along the line B-B′ of the covered laser diode devices1bshown inFIG.2AandFIG.2B. InFIG.1BandFIG.3A, the laser diode10has a laser diode chip100, and the laser diode chip100has two opposite sides (e.g., a side on the +Z direction and a side on the −Z direction shown inFIG.3A) with opposite conductivity types. For example, a side of the laser diode chip100adjacent to the first submount11is an n-type layer, a side of the laser diode chip100away from the first submount11is a p-type layer, and a p-n junction layer (or called active layer) is between the n-type layer and the p-type layer. When a forward current is introduced to the laser diode chip100, the electrons and the electron holes in the p-n junction layer will thus recombine and generate photons with the corresponding energy. The materials of the n-type layer, the p-type layer, and the p-n junction may be any combination of materials that can be arbitrarily matched with each other and still function normally, which is not limited herein.

InFIG.3A, a side of the laser diode10adjacent to the first submount11(e.g., an n-type layer) is electrically connected to the first electrode116; in the meantime, a side of the laser diode10away from the first submount11(e.g., a p-type layer) is electrically connected to the second electrode128. Hence, through the forward current introduced from the first electrode116(or the second electrode128) to the laser diode chip100, the p-n junction layer will thus generate photons with the corresponding energy. The materials of the first electrode116and the second electrode128may be any combination of materials that can be arbitrarily matched with each other and still function normally, which is not limited herein. The numbers, shapes, and locations of the first electrode116and the second electrode128may be arranged according to various demands, which are not limited herein. For example, takeFIG.2AandFIG.2Bas an example, each of the first electrode116and the second electrode128comprises two electrodes along the +Y direction, and any one of the first electrodes116and a corresponding one of the second electrodes128can be arranged on the same XZ plane.

According to some embodiments, the first submount11comprises a first submount body110, a first connection layer114, and a first electrode116(shown inFIG.3A). The laser diode10is electrically connected to the first electrode116through the first connection layer114. For example, inFIG.1BandFIG.3A, the first connection layer114is between the first submount body110and the laser diode10(shown inFIG.3A), a first end of the first connection layer114is electrically connected to the laser diode10, and a second end of the first connection layer114is electrically connected to the first electrode116. Hence, when the first electrode116is an n-type electrode, the first connection layer114may be used to guide the current of the laser diode10away from the laser diode10as far as possible. For example, the first connection layer114extends along the +Y direction shown inFIG.3Ato guide the current of the laser diode10to the first electrode116outside the second submount12(e.g., the exterior of the receiving space V shown inFIG.3A, which will be described later), and vice versa. The material of the first submount body110may be glass, plastic, rubber, ceramic, or a combination comprising two or more selected from the group consisting of glass, plastic, rubber, and ceramic; for example, the material of the first submount body110may be but not limited to ceramic heat dissipation material. Specifically, in some embodiments, the material of the first submount body110may be, for example, aluminum nitride (AlN), silicon, sapphire, or III-V semiconductor materials. The material of the first connection layer114may be any electrically conductive material, which may be but not limited to gold, tin, or gold-tin alloy. The material of the first electrode116may be any electrically conductive material, which may be but not limited to metal or alloy. Through electrically connecting an external device to the first electrode116outside the second submount12, the external device can be electrically connected to the laser diode10inside the second submount12rapidly; moreover, an electrically conductive channel (e.g., a via) on the second submount12is not further needed for the electrical connection between the first electrode116and the external device, and thus the time and cost for the manufacturing process can be reduced.

In some embodiments, the first submount11further comprises a first top plate112. The first top plate112is between the laser diode10and the first submount body110, and the first top plate112is electrically connected to the first connection layer114. For example, inFIG.3A, the first top plate112is between the first connection layer114and the first submount body110. For another example, the first top plate112is between the first connection layer114and the laser diode10. Hence, the laser diode10can be electrically connected to the first connection layer114through the first top plate112. The material of the first top plate112may be any electrically conductive material, which may be but not limited to gold, tin, or gold-tin alloy.

According to some embodiments, the second submount12comprises a second submount body120, a second connection layer122, a via124, and a second electrode128. The laser diode10is electrically connected to the second electrode128through the second connection layer122. For example, inFIG.2A,FIG.2B, andFIG.3A, the second connection layer122is on a side of the second submount body120adjacent to the laser diode10. The via124is penetratingly in the second submount body120. The second connection layer122and the second electrode128that are respectively on the two opposite sides (i.e., the two ends of the via124) are electrically connected to each other through the via124. For example, a first side of the second connection layer122is electrically connected to the laser diode10(e.g., through the bump14, which will be described later), and a second side of the second connection layer122is electrically connected to a first end of the via124, and a second end of the via124is electrically connected to the second electrode128. Therefore, when the second electrode128is a p-type electrode, the second connection layer122may be used to guide the current that is far away and dispersed to the laser diode10as close as possible. For example, the second connection layer122extends along an extending direction (e.g., the +Y direction shown inFIG.3A) that is substantially different from the extending direction of the first connection layer114(e.g., the −Y direction shown inFIG.3A), so that the current can be guided from the second electrode128outside the second submount12(e.g., the exterior of the receiving space V shown inFIG.3A) to the laser diode10, and vice versa. The material of the second submount body120may be metal, alloy, plastic, rubber, ceramic, or a combination comprising two or more selected from the group consisting of metal, alloy, plastic, rubber, and ceramic; for example, the material of the second submount body120may be but not limited to ceramic heat dissipation material. Specifically, in some embodiments, the material of the second submount body120may be, for example, AlN, aluminum oxide (Al2O3), silicon carbide (SiC), aluminum, copper, iron, or stainless steel. The material of the second connection layer122may be any electrically conductive material, which may be but not limited to gold, tin, or gold-tin alloy. The material of the second electrode128may be any electrically conductive material, which may be but not limited to metal or alloy. Accordingly, through electrically connecting an external device to the second electrode128outside the second submount12, the external device can be electrically connected to the laser diode10inside the second submount12rapidly.

In some embodiments, the via124is filled with a filling material, and the filling material may be but not limited to metal or alloy, such as tungsten. Therefore, the second connection layer122and the second electrode128that are respectively on the two opposite sides (i.e., the two ends of the via124) may be electrically connected to each other through the via124. The number, shape, and location of the via124may be arranged according to various demands, which are not limited herein. For example, any two of the via124may be grouped and arranged (that is, a pair of the via124); for example, at least one group of the via124(i.e., two of the via124) can be arranged sequentially along the +Y direction shown inFIG.2B. In some embodiments, the location of the via124may be adjusted according to the arrangement of the second electrode128; for example, the via124is adjacent to the second electrode128while the second electrode128is not needed to be directly on the corresponding via124. Hence, in some embodiments, through the via124that can be arranged in any shape and on any location of the second submount body120, not only a denser and more sophisticated wiring but also a more effectively enhanced cooling performance of the laser diode10can be provided.

In some embodiments, the second submount12further comprises a second top plate123. The second top plate123is on a side of the second connection layer122away from the laser diode10, and the second top plate123is electrically connected to the second connection layer122. Hence, the second connection layer122can be electrically connected to the second electrode128through the second top plate123. For example, inFIG.3A, the second top plate123is between the second connection layer122and the second electrode128. For another example, the second top plate123is between the second connection layer122and the laser diode10. For example, the second top plate123is on a side of the second connection layer122adjacent to the laser diode10, and the second top plate123is electrically connected to the second connection layer122. Hence, the laser diode10can be electrically connected to the second connection layer122through the second top plate123. The material of the second top plate123may be any electrically conductive material, which may be but not limited to gold, tin, or gold-tin alloy.

According to some embodiments, the second submount12further comprises a third top plate126. The third top plate126is between the via124and the second electrode128, and the third top plate126is electrically connected to the via124to allow the via124and the second electrode128to be electrically connected to each other through the third top plate126. For example, inFIG.3A, the third top plate126is between the second submount body120and the second electrode128. The material of the third top plate126may be any electrically conductive material, which may be but not limited to gold, tin, or gold-tin alloy.

Please refer toFIG.3A. According to some embodiments, the laser diode device1bfurther comprises one or more side walls13. The side wall(s)13is between the first submount11and the second submount12to form a receiving space V among the first submount11, the laser diode10, the second submount12, and the side wall(s)13. InFIG.3A, the laser diode device1bfurther comprises two side walls13respectively on two sides of the laser diode10, and each of the side walls13comprises a sidewall body130and a sidewall connection layer132. Each of the sidewall bodies130is between the first submount11and the second submount12. One of two ends of each of the sidewall bodies130is connected to (e.g., by welding or bonding) the first submount11through the sidewall connection layer132, and the other end of the each of the sidewall bodies130is connected to the second submount12. The stacked height (along the Z direction shown inFIG.3A) of each of the sidewall bodies130(which are respectively on two sides of the second submount12) and the corresponding one of the sidewall connection layers132is substantially identical to the stacked height (along the Z direction) of the laser diode10and the corresponding bump14. The material of the sidewall body130may be glass, metal, alloy, plastic, rubber, ceramic, or a combination comprising two or more selected from the group consisting of glass, metal, alloy, plastic, rubber, and ceramic; for example, the material of the sidewall body130may be but not limited to ceramic heat dissipation material. Specifically, in some embodiments, the material of the sidewall body130may be, for example, AlN, Al2O3, SiC, aluminum, copper, iron, or stainless steel. The material of the sidewall connection layer132may be any electrically conductive material, which may be but not limited to gold, tin, or gold-tin alloy. Therefore, in some embodiments, through the side wall(s)13, the receiving space V with a sufficient height can be provided by the laser diode device1b, so that the waveguide102can be prevented from being damaged caused by the direct contact between the waveguide102and the second submount12(and/or the waveguide102can be prevented from being squeezed caused by the thermal expansion of the second submount12). In some embodiments, the side wall(s)13and the second submount12are integrally formed as a one-piece member, so that the connection between the side wall(s)13and the second submount12can be enhanced.

In some embodiments, through the first submount11and the second submount12, double heat flows (DHFs) may be formed on two opposite sides of the laser diode10(i.e., a side of the laser diode10adjacent to the first submount11and a side of the laser diode10adjacent to the second submount12), so that a parallel-like circuit (with a lower overall resistance) is thus formed to be further electrically connected to the junction element(s) (not illustrated) at the two sides of the laser diode10. Since the existing laser diode device (e.g., the uncovered laser diode device1ashown inFIG.1A) only has, for example, the first submount11and does not covered by the second submount12and the second connection layer122, the junction element(s) is electrically connected to the upper side of the laser diode10directly and thus only a single heat flow (SHF) is formed. Therefore, a series-like circuit (with a higher overall resistance) would be formed by two opposite sides of the existing laser diode10. Hence, in some embodiments, compared with the existing uncovered laser diode device1a, the laser diode device1bcan have the characteristics of a lower overall resistance and a less generated heat.

According to some embodiments, the laser diode10is electrically connected to the second electrode128through the bump14. For example, inFIG.3A, one of two ends of the bump14(e.g., an end of the bump14adjacent to the laser diode10) is electrically connected to the laser diode10, and the other end of the bump14(e.g., an end of the bump14away from the laser diode10) is electrically connected to the second connection layer122and further electrically connected to the second electrode128through the via124.

InFIG.3A, the bump14is adjacent to the waveguide102and on the laser diode10. For example, a distance (along the +Y direction shown inFIG.3A) between the bump14and the waveguide102may be at least 4 μm, and a distance between the bump14and the edge of the laser diode chip100may be at least 5 μm, so that the operation of the waveguide102and/or the laser diode chip100can be prevented from being affected. The material of the waveguide102may be but not limited to any material that can be used as a photoresist, such as silicon, silicon dioxide, indium phosphide (InP), gallium arsenide (GaAs), or a combination comprising two or more selected from the group consisting of silicon, silicon dioxide, indium phosphide (InP), and gallium arsenide (GaAs). The shape of the waveguide102may be but not limited to a strip waveguide (e.g., a rectangular waveguide or a ridge waveguide) or a rib waveguide.

Please refer toFIG.3A,FIG.3B, andFIG.4.FIG.3Billustrates a schematic cross-sectional view along the line C-C′ of the covered laser diode device1bshown inFIG.3A; andFIG.4illustrates an enlarged partial perspective view of the laser diode10shown inFIG.3A. In the schematic cross-sectional views ofFIG.3AandFIG.4, the waveguide102has a height H2extending from the laser diode10toward the second submount12(e.g., the +Z direction shown inFIG.3A). The waveguide102has a bottom width d2(along the +Y direction) on a side of the waveguide102adjacent to the laser diode10, and the waveguide102has a top width d2′ (along the +Y direction) on a side of the waveguide102away from the laser diode10. The top width d2′ of the waveguide102may be substantially identical to or different from the bottom width d2of the waveguide102. For example, when the top width d2′ is less than or greater than the bottom width d2, the waveguide102may be a ridge waveguide; for an alternative example, when the top width d2′ is substantially equal to the bottom width d2, the waveguide102may be a rectangular waveguide. In the top view shown inFIG.3B, the waveguide102may be on the laser diode10(i.e., on the laser diode chip100) and extend along the +X direction, so that a strip waveguide extending along +X direction may be formed.

The bump14may be but not limited to a stud bump140(shown inFIG.3AandFIG.3B, which will be described later), a second submount protrusion142(shown inFIG.10, which will be described later), a conductive paste144(shown inFIG.11, which will be described later), or a combination comprising two or more selected from the group consisting of the stud bump140, the second submount protrusion142, and the conductive paste144. The material of the bump14may be any electrically conductive and/or thermally conductive material.

In some embodiments, the bump14is a stud bump140. The material of the stud bump140may be but not limited to gold, copper, silver, tin, or gold-tin alloy. Please refer toFIG.3AandFIG.4. The stud bump140has a height H1extending from the laser diode10toward the second submount12(e.g., the +Z direction shown inFIG.3A), and the height H1of the stud bump140is substantially higher than the height H2of the waveguide102. For example, the height H1of the stud bump140is between about 50 μm and about 60 μm, and the height H2of the waveguide102is between about 1 μm and about 3 μm (e.g., about 2 μm). The stud bump140has a bottom width (i.e., a first diameter d1; along the +Y direction) on a side of the stud bump140adjacent to the laser diode10, and the stud bump140has a top width (i.e., a second diameter d1′; along the +Y direction) on a side of the stud bump140away from the laser diode10. The first diameter d1may be substantially identical to or different from the second diameter d1′; for example, a ratio of the first diameter d1over the second diameter d1′ is between 0.9 and 1.1; that is, a relationship between the first diameter d1and the second diameter d1′ complies with the following Eq. (1).

InFIG.3B, the geometric arrangement of the stud bump140along the X direction may be substantially identical to or different from the geometric arrangement of the stud bump140along the Y direction. For example, inFIG.3B, the stud bump140also has a bottom width (along the X direction) on a side of the stud bump140adjacent to the laser diode10, and the stud bump140has a top width (along the X direction) on a side of the stud bump140away from the laser diode10. The bottom width and the top width along the X direction are substantially identical to the bottom width (i.e., the first diameter d1) and the top width (i.e., the second diameter d1′) along the Y direction, and thus a cylindrical stud bump140may be formed. The cylindrical stud bump140may be manufactured on the laser diode10(i.e., the laser diode chip100) by wire bonding. In some embodiments, the first diameter d1of the cylindrical stud bump140may be substantially identical to or different from the height H1of the stud bump140. For example, a ratio of the first diameter d1of the cylindrical stud bump140over the height H1of the stud bump140is between 0.85 and 1.1; that is, a relationship between the first diameter d1and the height H1of the stud bump140complies with the following Eq. (2). For example, the first diameter d1of the cylindrical stud bump140is between about 50 μm and about 60 μm, and the height H1of the stud bump140is between about 50 μm and about 60 μm. For another example, the first diameter d1of the cylindrical stud bump140may be between about 50 μm and about 60 μm, the height H1of the stud bump140may be about 58 μm, and thus the ratio of the first diameter d1of the stud bump140over the height H1may be, for example, between 0.86 and 1.03.

In some embodiments, the bump14may be one or more stud bumps140. Each of the stud bumps140is adjacent to the waveguide102and distributed over a side of the laser diode10adjacent to the second submount12. In other words, the number of the stud bump(s)140may be one or more; for example, the number of the stud bump(s)140may be at least one, between 1 and 18, at least three, between 3 and 18, between 3 and 15, between 3 and 12, between 3 and 9, or between 3 and 6. For example, inFIG.3B, the number of the bumps14are three and these bumps14are adjacent to the waveguide102and sequentially arranged along the X direction. In some embodiments, a ratio of a sum of the bottom area of the stud bump(s)140(which is denoted as A1herein) over a surface area of the laser diode10(i.e., the laser diode chip100) (which is denoted as A2herein) is between 0.02 and 0.30. In other words, a relationship between the sum A1of the bottom area of the stud bump(s)140and the surface area A2of the laser diode10complies with the following Eq. (3). For example, the first diameter d1of the bumps140may be between about 50 μm and about 60 μm, the number of the stud bumps140may be between 3 and 18, the length and the width of the laser diode10are respectively 1,000 μm and 200 μm, and thus the sum A1of the bottom area of the stud bumps140over the surface area A2of the laser diode10may be, for example, between 0.0294 and 0.254.

Please refer toFIG.1A,FIG.2A, andFIG.5at the same time.FIG.5illustrates a simulated surface temperature profile of an uncovered laser diode device1aand a covered laser diode device1b(having the stud bumps140) according to some embodiments. InFIG.5, the uncovered laser diode device1acan be referred to the uncovered laser diode device1ashown inFIG.1A, while the covered laser diode device1b(having three stud bumps140), which is briefly referred to as “the covered laser diode device1b”, can be referred to the laser diode device1bshown inFIG.2A(orFIG.2B). Each of the uncovered laser diode device1aand the covered laser diode device1bis applied with a power of 477 mW, so that each of the uncovered laser diode device1aand the covered laser diode device1bcan be used as a heat source that can be sufficiently dissipated to reach a thermal equilibrium with the environment. The highest surface temperatures of the uncovered laser diode device1aand the covered laser diode device1bthen can be obtained by simulation, and as shown inFIG.5, the highest surface temperatures of the uncovered laser diode device1aand the covered laser diode device1bare respectively about 70° C. and about 50° C. In other words, as compared to the uncovered laser diode device1a, the covered laser diode device1b(having the stud bumps140) can have a temperature reduction of 28.6%. Accordingly, through the cover (e.g., the second submount12) and the stud bump(s)140, the laser diode device1bcan indeed enhance the surface cooling performance of the laser diode10effectively, thereby greatly reducing the surface temperature of the laser diode10.

Please refer toFIG.6AandFIG.6B.FIG.6Aillustrates a simulated surface temperature profile of a covered laser diode device1b(having one or more of the stud bumps140) according to some embodiments; andFIG.6Billustrates a simulated surface temperature profile of the covered laser diode device1b(having one or more of the stud bumps140) shown inFIG.6A. The experimental methods and conditions applied inFIG.6AandFIG.6Bare the same as those ofFIG.5, and will not be described in detail herein. InFIG.6A, the simulated surface temperature profiles of the laser diode chips100having the waveguide102and the stud bumps140are illustrated, and the numbers (which is represented by “N”) of the stud bumps140of each of the laser diode chips100are 0, 3, 6, 9, 12, 15, and 18, respectively. From the result of the surface temperature profiles shown inFIG.6A, when the laser diode chip100is not equipped with the stud bump140(i.e., N=0), the surface temperatures of a quite large region of the laser diode chip100adjacent to the waveguide102is greater than about 49.6° C., while the surface temperatures of another large region is between about 47.6° C. and about 49.6° C., and only the four corners of the laser diode chip100respectively have a lower temperature which is between about 45.6° C. and about 47.6° C. That is, if the laser diode chip100is not equipped with the stud bump140(i.e., N=0), the difference between the surface temperature on the laser diode10and the temperature of the waveguide102is merely about 7° C. In other words, the surface temperature of the laser diode chip100that is not equipped with the stud bump140(i.e., N=0) cannot be reduced effectively, thereby leading to an apparently poorer cooling performance. In contrast, when the laser diode chip100is further equipped with the stud bumps140(whichever N=3, 6, 9, 12, 15, or 18), the surface temperature of a quite small region of the laser diode chip100adjacent to the waveguide102is greater than about 41.2° C., while the surface temperatures of the rest regions of the laser diode chip100are all between about 30.9° C. and about 36.1° C. Hence, the overall surface temperature profiles of the laser diode chips100having the stud bumps140are apparently more uniformed, and the overall surface temperature of the laser diode chips100can be indeed reduced greatly and effectively. In other words, the surface temperature of the laser diode chip100(and the profiles thereof) are basically not affected by varying the number N of the stud bumps140at least in a certain range of N (e.g., 0<N≤18). Furthermore, once the laser diode chip100is equipped with the stud bump(s)140, the surface cooling performance of the laser diode10can be enhanced effectively, and the heat on the surface of the laser diode10can be also prevented from being accumulated at a certain area of the surface of the laser diode10.

Further, according to the highest surface temperatures of the laser diode chips100shown inFIG.6B(which correspond to the laser diode chips100shown inFIG.6A), when the laser diode chip100is not equipped with the stud bump140(i.e., N=0), the highest surface temperature of the laser diode chip100is about 55° C.; in contrast, when the laser diode chip100is further equipped with the stud bumps140(whichever N=3, 6, 9, 12, 15, or 18), the highest surface temperatures of the laser diode chips100are between about 40° C. and about 43° C. Therefore, the highest surface temperatures of the laser diode chips100having the stud bumps140can be indeed reduced greatly and effectively. In other words, the highest surface temperature of the laser diode chip100are basically not affected by varying the number N of the stud bumps140at least in a certain range of N (e.g., 0<N≤18). Furthermore, once the laser diode chip100is equipped with the stud bump(s)140, the surface cooling performance of the laser diode10can be enhanced effectively, thereby greatly reducing the surface temperature of the laser diode10.

Please refer toFIG.7.FIG.7illustrates a schematic cross-sectional view along the line C-C′ as shown inFIG.3Aof the covered laser diode device1baccording to some embodiments. For example, inFIG.7, the second submount12comprises the second connection layer122and the second electrode128(which may optionally not include the second submount body120, the via124, and the third top plate126). Two ends of the second connection layer122are respectively on the side walls13. The second electrode128is on the second connection layer122, and the laser diode10is electrically connected to the second electrode128through the second connection layer122.

InFIG.7, the side walls13of the laser diode device1bare the two side walls13respectively on the two sides of the laser diode10, and each of the side walls13comprises a sidewall body130and one or more sidewall interposer layers134. Each of the sidewall bodies130is between the first submount11and the second submount12. One of two ends of each of the sidewall bodies130is connected to the first submount11through the sidewall interposer layer(s)134, and the other end of each of the sidewall bodies130is connected to the second submount12. Through the stacking of one or more sidewall interposer layers134, the height of each of the side walls13may be further adjusted, so that the stacked height (along the Z direction shown inFIG.7) of the sidewall bodies130at the two sides of the second submount12and the corresponding sidewall interposer layer(s)134may be substantially identical to the stacked height (along the Z direction shown inFIG.7) of the laser diode10and the corresponding bumps14. The material of the sidewall interposer layer134and the material of the sidewall body130may be substantially identical to or matched with each other, which may independently be glass, metal, alloy, plastic, rubber, ceramic, or a combination comprising two or more selected from the group consisting of glass, metal, alloy, plastic, rubber, and ceramic; for example, the material of the sidewall interposer layers134and/or the sidewall bodies130may be but not limited to ceramic heat dissipation material. Specifically, in some embodiments, the material of the sidewall interposer layers134and/or the sidewall bodies130may be, for example, AlN, A12O3, SiC, aluminum, copper, iron, or stainless steel. The term “matched” refers to the physical and/or chemical properties of two materials are not greatly different from each other; for example, the coefficients of thermal expansion of the two materials are close to each other. Therefore, through the sidewall body130(and the sidewall interposer layer(s)134of the sidewall body130), the receiving space V with a sufficient height can be provided by the laser diode device1b, so that the waveguide102can be prevented from being damaged caused by the direct contact between the waveguide102and the second submount12(and/or the waveguide102can be prevented from being squeezed caused by the thermal expansion of the second submount12).

InFIG.7, the laser diode10further comprises one or more chip interposer layers104, and the chip interposer layer(s)104is between the laser diode chip100and the first submount11. Through the stacking of one or more chip interposer layers104, the height of the laser diode chip100and the bump(s)14in the receiving space V may be further adjusted, so that the stacked height (along the Z direction shown inFIG.7) of the sidewall bodies130at the two sides of the second submount12may be substantially identical to the stacked height (along the Z direction shown inFIG.7) of the laser diode10and the corresponding bumps14. The material of the chip interposer layer(s)104may be glass, metal, alloy, plastic, rubber, ceramic, or a combination comprising two or more selected from the group consisting of glass, metal, alloy, plastic, rubber, and ceramic; for example, the material of the chip interposer layer(s)104may be but not limited to ceramic heat dissipation material. Specifically, in some embodiments, the material of the chip interposer layer(s)104may be, for example, AlN, A12O3, SiC, aluminum, copper, iron, or stainless steel. Therefore, through the chip interposer layer(s)104, the receiving space V with a sufficient height can be provided by the laser diode device1b, so that the bumps14can be electrically connected to the second submount12(i.e., the second submount body120) more properly.

Please refer toFIG.8.FIG.8illustrates a schematic cross-sectional view along the line C-C′ as shown inFIG.3Aof the covered laser diode device1baccording to some embodiments. For example, inFIG.8, the second submount12comprises the second submount body120, the second connection layer122, and the second electrode128(which may optionally not include the via124and the third top plate126). Two ends of the second connection layer122are respectively on the side walls13. The second submount body120is on the second connection layer122. The second connection layer122may, for example, extend along the −Y direction shown inFIG.8to expose parts of the second connection layer122, and the second electrode128is on the exposed parts of the second connection layer122. The laser diode10is electrically connected to the second electrode128through the second connection layer122, so that the current can be guided from the second electrode128outside the second submount12(e.g., the exterior of the receiving space V shown inFIG.8) to the laser diode10, and vice versa.

InFIG.8, the side walls13of the laser diode device1bare the two side walls13respectively on the two sides of the laser diode10, and each of the side walls13comprises a sidewall body130and one or more sidewall interposer layers134. Each of the sidewall bodies130is between the first submount11and the second submount12. One of two ends of each of the sidewall bodies130is connected to the first submount11through the sidewall interposer layer(s)134, and the other end of each of the sidewall bodies130is connected to the second submount12. The arrangement embodiments of the sidewall body130and the sidewall interposer layer134may be referred to the aforementioned embodiments, and will not be described in detail herein.

Please refer toFIG.9.FIG.9illustrates a schematic cross-sectional view along the line C-C′ as shown inFIG.3Aof the covered laser diode device1baccording to some embodiments. The arrangement embodiments of the laser diode device1bshown inFIG.9can be referred to the aforementioned embodiments, and will not be described in detail herein. The major difference betweenFIG.9and the aforementioned embodiments is that, inFIG.9, a portion of or all of the receiving space V is filled with a filling material15. For example, at least between the bump14(e.g., the stud bump140) and the second submount12in the receiving space V is filled with the filling material15. The filling material15comprises an insulating base150and a plurality of conductive particles152. The conductive particles152are distributed over the insulating base150, and parts of the conductive particles152are between the bump14and the second submount12. The filling material15may be any anisotropic conductive material, such as (but not limited to) an anisotropic conductive paste (ACP) or an anisotropic conductive film (ACF). When a pressure is applied to the conductive particles152between the bump14and the second submount12, the conductive particles152subjected to the applied pressure will be fused and combined with each other, thereby forming at least one conductive channel. The bump14and the second submount12will thus be electrically connected to each other through the conductive channel. Meanwhile, because the insulating base150is still filled between those conductive particles152that are not subjected to the applied pressure, those conductive particles152will not be conducted with each other. Therefore, even though the conductive channel has been formed between the bump14and the second submount12, the receiving space V filled with the filling material15still cannot be shirt-circuited. Hence, through the bump14and the filling material15, the electric connection between the bump14and the second submount12can be further enhanced, so that the thermal energy on the surface of the laser diode10can be reduced effectively. Moreover, the insulating base150of the filling material15can be also used as an underfill, and thus moisture can be prevented from entering the laser diode10, thereby enhancing the service life of the laser diode10.

Please refer toFIG.10.FIG.10illustrates a schematic cross-sectional view along the line C-C′ as shown inFIG.3Aof the covered laser diode device1baccording to some embodiments. The arrangement embodiments of the laser diode device1bshown inFIG.10can be referred to the aforementioned embodiments, and will not be described in detail herein. The major difference betweenFIG.10and the aforementioned embodiments is that, inFIG.10, the bump14is the second submount protrusion142. The second submount protrusion142extends from the second submount12(i.e., the second submount body120) to allow the second electrode128and the laser diode10to be electrically connected to each other through the second submount protrusion142. A side of the second submount protrusion142adjacent to the second submount12(i.e., the second submount body120) has a top width, and a side of the second submount protrusion142away from the second submount12(i.e., the second submount body120) has a bottom width. The top width of the second submount protrusion142may be substantially identical to or different from the bottom width of the second submount protrusion142. For example, inFIG.10, the top width of the second submount protrusion142is greater than the bottom width of the second submount protrusion142, so that a second substrate protrusion142is formed as an inverted ridge structure having a wide top and a narrow bottom. The second substrate protrusion142with the inverted ridge structure (having a wide top and a narrow bottom) can be more suitable for the manufacturing of the second submount12and the second submount protrusion142. For example, the second submount protrusion142and the second submount body120may be integrally formed as a one-piece member, so that the complicated manufacturing process can be reduced and the connection between the second submount protrusion142and the second submount body120can be enhanced, thereby providing the second submount12and the second submount protrusion142with a more stable quality. The material of the second submount protrusion142and the material of the second submount body120may be substantially identical to or matched with each other, which may independently be metal, alloy, plastic, rubber, ceramic, or a combination comprising two or more selected from the group consisting of metal, alloy, plastic, rubber, and ceramic; for example, the material of the second submount protrusion142and/or the second submount body120may be but not limited to ceramic heat dissipation material. Specifically, in some embodiments, the material of the second submount protrusion142and/or the second submount body120may be, for example, AlN, A12O3, SiC, aluminum, copper, iron, or stainless steel. The term “matched” refers to the physical and/or chemical properties of two materials are not greatly different from each other; for example, the coefficients of thermal expansion of the two materials are close to each other. In some embodiments, the second submount12further comprises the second connection layer122. The second connection layer122is between the second submount protrusion142and the laser diode10to allow the laser diode10and the second electrode128(including the second submount body120and the second submount protrusion142) to be electrically connected to each other through the second connection layer122. The arrangement embodiments of the second connection layer122can be referred to the aforementioned embodiments, and will not be described in detail herein.

Please refer toFIG.11.FIG.11illustrates a schematic cross-sectional view along the line C-C′ as shown inFIG.3Aof the covered laser diode device1baccording to some embodiments. The arrangement embodiments of the laser diode device1bshown inFIG.11can be referred to the aforementioned embodiments, and will not be described in detail herein. The major difference betweenFIG.11and the aforementioned embodiments is that, inFIG.11, the bump14is the conductive paste144. The conductive paste144is on a side of the laser diode10adjacent to the second submount12to allow the laser diode10and the second submount12(i.e., the second electrode128) to be electrically connected to each other through the conductive paste144. The material of the conductive paste144may be but not limited to silver, tin, copper, gold, carbon, or alloy comprising two or more selected from the group consisting of silver, tin, copper, gold, and carbon, and for example, a silver paste, a copper paste, a gold paste, a carbon paste, a tin ball, or a combination comprising two or more selected from the group consisting of a silver paste, a copper paste, a gold paste, and a carbon paste may be thus formed. Since the conductive paste144is in a fluid state during the manufacturing process, the conductive paste144in the fluid state not only can be directly arranged on the laser diode chip100, but also can be directly arranged on the waveguide102. Furthermore, since the cured conductive paste144can have appearance and shape that are substantially conformal to the appearances and shapes of the laser diode chip100and the waveguide102, not only a superior electrical connection can be established between the laser diode10and the second submount12, damage and/or squeeze of the waveguide102caused by the cured conductive paste144can be also avoided. Through the conductive paste144, the laser diode10and the second submount12(i.e., the second electrode128) can be electrically connected to each other through a larger connection area, so that the overall resistance can be reduced more effectively, thereby generating a less thermal energy. Moreover, owing to the fluidic characteristic of the conductive paste144during the manufacturing process, the conductive paste144can be directly arranged on the laser diode chip100without intentionally avoiding the waveguide102, thereby greatly reducing the time and cost for the manufacturing process of the laser diode device1bas compared with the time and cost for the existing manufacturing process.

Please refer toFIG.12.FIG.12illustrates a schematic block diagram of an optical transceiver system2according to some embodiments. InFIG.12, an optical transceiver system2is provided, wherein the optical transceiver system2comprises an optical fiber24, a lens22, and a laser diode device1b. The optical fiber24is adapted to transmit a light source (or an optical signal), such as adapted to emit a light source (or an optical signal) and/or receive a light source (or an optical signal). The lens22is adjacent to the optical fiber24to receive and/or emit the light source (or the optical signal). The arrangement embodiments of the laser diode device1bcan be referred to the aforementioned embodiments, and will not be described in detail herein. The laser diode10may be configured to be communicatively connected to the lens22and the optical fiber24through the light source. For example, the laser diode driver20is adapted to receive the light source (or the optical signal) from the lens22or emit the light source (or the optical signal) to the lens22and the optical fiber24. For example, when the optical fiber24is configured to emit a light source (or an optical signal), the lens22is thus configured to receive the light source (or the optical signal) from the optical fiber24to further emit the light source (or the optical signal) to the laser diode device1b; or for another example, when the optical fiber24is configured to receive a light source (or an optical signal), the lens22is thus configured to receive the light source (or the optical signal) from the laser diode device1bto further emit the light source (or the optical signal) to the optical fiber24. In some embodiments, through the laser diode10that is communicatively connected to those light sources (i.e., receiving those light sources from the optical fiber24and/or emitting those light sources to the optical fiber24), the optical transceiver system2can be used as an optical subassembly (OSA) for high-speed signal transmission, such as a transmitter optical subassembly (TOSA), a receiver optical subassembly (ROSA), or a combination of TOSA and ROSA.

InFIG.12, according to some embodiments, the optical transceiver system2which is used as an optical subassembly (OSA) for high-speed signal transmission may be combined with an electrical subassembly (ESA) to be driven by the ESA so as to be further combined and used as a light-transmitting module for high-speed signal transmission. The ESA may be, for example, a laser diode driver20. For example, inFIG.12, the optical transceiver system2further comprises a laser diode driver20. The laser diode driver20is electrically connected to the laser diode device1b, and the laser diode driver20emits a driving signal (e.g., a differential voltage signal or a current driving signal) to the laser diode device1bto allow the laser diode10of the laser diode device1bto be communicatively connected to the lens22and the optical fiber24through the light source. For example, the laser diode10of the laser diode device1bis adapted to receive the light source (or the optical signal) from the lens22or emit the light source (or the optical signal) to the lens22and the optical fiber24. Hence, through the laser diode device1bhaving a superior cooling performance, the optical transceiver system2can thus have much broader and more diverse applications without being limited by the shortcomings of the poorer cooling performance encountered by the existing device.

To sum up, in some embodiments, through a bump, a first electrode, and a second electrode, a laser diode (and the first electrode) and the second electrode that are respectively on two sides of the bump can be electrically connected to each other and thus double heat flows (DHFs) may be formed, so that an overall resistance of a parallel-like circuit may be further formed. Therefore, in some embodiments, an optical transceiver system (and the laser diode device of the optical transceiver system) can provide with a much lower overall resistance as compared with those of the existing devices and thus with a much less generated thermal energy, thereby enhancing the surface cooling performance of the laser diode effectively at the same time. Furthermore, in some embodiments, through a height of the bump that is substantially higher than a height of the waveguide, the waveguide of the optical transceiver system (and the laser diode device of the optical transceiver system) can be prevented from being damaged caused by the cover of a second submount (and/or being squeezed by the second submount caused by the thermal expansion of the second submount).

Although the present disclosure is disclosed in the foregoing embodiments as above, it is not intended to limit the present disclosure. Any person who is familiar with the relevant art can make some changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of the present disclosure shall be subject to the definition of the scope of patent application attached to the specification.