OPTICAL MODULE

An optical module includes a circuit board, a substrate, a laser assembly, and a silicon photonic chip. The silicon photonic chip is electrically connected to the circuit board through the substrate so as to ground the silicon photonic chip. The substrate includes a body, a first support step, and a second support step. The first support step is disposed at an end of the body. The second support step is disposed at another end of the body. The circuit board includes a first metal layer and a second metal layer. The first metal layer is disposed on a surface of the circuit board proximate to the first support step and is electrically connected to the first support step. The second metal layer is disposed on a surface of the circuit board proximate to the second support step and is electrically connected to the second support step.

TECHNICAL FIELD

The present disclosure relates to the field of optical communication technologies, and in particular, to an optical module.

BACKGROUND

Optical communication technologies are used in cloud computing, mobile Internet, video conferencing, and other new businesses and application models. In optical communication, an optical module is a tool for achieving interconversion between an optical signal and an electrical signal, and is a key component in an optical communication device. Using a silicon photonic chip to implement a photoelectric conversion function has become a mainstream solution adopted by high-speed optical modules.

SUMMARY

In an aspect, an optical module is provided. The optical module includes a circuit board, a substrate, a laser assembly, and a silicon photonic chip. The circuit board includes a through hole disposed in a surface of the circuit board. The substrate is disposed in the through hole. The laser assembly is disposed on the substrate. The silicon photonic chip is disposed on the substrate and is optically connected to the laser assembly, and the silicon photonic chip is electrically connected to the circuit board through the substrate so as to ground the silicon photonic chip. The substrate includes a body, a first support step, and a second support step. The body is disposed in the through hole, and the laser assembly and the silicon photonic chip are disposed on the body. The first support step is disposed at an end of the body and is configured to support the circuit board. The second support step is disposed at another end of the body and is configured to support the circuit board. The circuit board includes a first metal layer and a second metal layer. The first metal layer is disposed on a surface of the circuit board proximate to the first support step and corresponds to a position of the first support step, and the first metal layer is electrically connected to the first support step. The second metal layer is disposed on a surface of the circuit board proximate to the second support step and corresponds to a position of the second support step, and the second metal layer is electrically connected to the second support step.

In another aspect, an optical module is provided. The optical module includes a circuit board, a substrate, a laser assembly and a silicon photonic chip. The circuit board includes a blind hole disposed in a surface thereof, and the blind hole includes a metal layer disposed on a bottom surface thereof. The substrate is disposed in the blind hole and is located on the metal layer, and the substrate is electrically connected to the circuit board through the metal layer. The laser assembly is disposed on the substrate. The silicon photonic chip is disposed on the substrate and is optically connected to the laser assembly, and the silicon photonic chip is electrically connected to the circuit board through the substrate so as to ground the silicon photonic chip.

DETAILED DESCRIPTION

Hereinafter, the terms such as “first” and “second” are used for descriptive purposes only, and are not to be construed as indicating or implying the relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with “first” and “second” may explicitly or implicitly include one or more of these features. In the description of the embodiments of the present disclosure, the term “a/the plurality of” means two or more unless otherwise specified.

In the description of some embodiments, the terms “coupled,” “connected,” and derivatives thereof may be used. The term “connection” should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; and it may be a direct connection, or may be an indirect connection through an intermediate medium. The term “coupled” or “communicatively coupled,” however, may also mean that two or more elements are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content herein.

The usage of the phrase “applicable to” or “configured to” herein indicates an open and inclusive expression, which does not exclude devices that are applicable to or configured to perform additional tasks or steps.

The terms “about,” “substantially,” and “approximately” as used herein includes a stated value and an average value within an acceptable range of deviation of a particular value. The acceptable range of deviation is determined by a person of ordinary skill in the art in consideration of the measurement in question and errors associated with the measurement of a particular quantity (i.e., limitations of the measurement system).

In an optical communication system, an optical signal is used to carry information to be transmitted, and the optical signal carrying the information is transmitted to an information processing device such as a computer through an information transmission device such as an optical fiber or an optical waveguide, so as to achieve transmission of the information. Due to the passive transmission characteristic of light when being transmitted through the optical fiber or the optical waveguide, low-cost and low-loss information transmission may be achieved. In addition, since a signal transmitted by the information transmission device such as the optical fiber or the optical waveguide is an optical signal, and a signal that can be recognized and processed by the information processing device such as the computer is an electrical signal, in order to establish information connection between the information transmission device such as the optical fiber or the optical waveguide and the information processing device such as the computer, interconversion between the electrical signal and the optical signal needs to be achieved.

In the field of optical fiber communication technology, an optical module may achieve the interconversion between the optical signal and the electrical signal. The optical module includes an optical port and an electrical port. The optical module achieves optical communication with the information transmission device such as the optical fiber or the optical waveguide through the optical port, and the optical module achieves electrical connection with an optical network terminal (e.g., an optical modem) through the electrical port. The electrical connection is mainly used for implementing power supply,120signal transmission, data information transmission, and grounding. The optical network terminal transmits the electrical signal to the information processing device such as the computer through a network cable or wireless fidelity (Wi-Fi).

FIG.1is a diagram showing a connection relationship of an optical communication system, in accordance with some embodiments. As shown inFIG.1, the optical communication system includes a remote server1000, a local information processing device2000, an optical network terminal100, an optical module200, an optical fiber101, and a network cable103.

An end of the optical fiber101is connected to the remote server1000, and another end thereof is connected to the optical network terminal100through the optical module200. The optical fiber itself supports long-distance signal transmission, for example, signal transmission over several kilometers (6 kilometers to 8 kilometers). Based on this, if repeaters are used, theoretically, it may be possible to achieve infinite-distance transmission. Therefore, in a typical optical communication system, a distance between the remote server1000and the optical network terminal100may typically reach several kilometers, dozens of kilometers, or hundreds of kilometers.

An end of the network cable103is connected to the local information processing device2000, and another end thereof is connected to the optical network terminal100. The local information processing device2000includes one or more of a router, a switch, a computer, a mobile phone, a tablet computer, or a television.

A physical distance between the remote server1000and the optical network terminal100is greater than a physical distance between the local information processing device2000and the optical network terminal100. A connection between the local information processing device2000and the remote server1000is achieved by the optical fiber101and the network cable103, and a connection between the optical fiber101and the network cable103is achieved by the optical module200and the optical network terminal100.

The optical module200includes an optical port and an electrical port. The optical port is configured to connect to the optical fiber101, so that a bidirectional optical signal connection is established between the optical module200and the optical fiber101. The electrical port is configured to connect to the optical network terminal100, so that a bidirectional electrical signal connection is established between the optical module200and the optical network terminal100. The optical module200may achieve interconversion between the optical signal and the electrical signal, so that an information connection is established between the optical fiber101and the optical network terminal100. For example, an optical signal from the optical fiber101is converted into an electrical signal by the optical module200, and then the electrical signal is input to the optical network terminal100; and an electrical signal from the optical network terminal100is converted into an optical signal by the optical module200, and then the optical signal is input to the optical fiber101. Since the optical module200is a tool for achieving interconversion between the optical signal and the electrical signal and doesn't have a data processing function, the information does not change in the above photoelectric conversion process.

The optical network terminal100includes a housing in a substantially cuboid shape, and an optical module interface102and a network cable interface104that are disposed on the housing. The optical module interface102is configured to connect to the optical module200, so that a bidirectional electrical signal connection is established between the optical network terminal100and the optical module200. The network cable interface104is configured to connect to the network cable103, so that a bidirectional electrical signal connection is established between the optical network terminal100and the network cable103. A connection between the optical module200and the network cable103is established through the optical network terminal100. For example, the optical network terminal100transmits an electrical signal from the optical module200to the network cable103, and transmits an electrical signal from the network cable103to the optical module200. Therefore, the optical network terminal100, as a master monitor of the optical module200, may monitor operation of the optical module200. In addition to the optical network terminal100, the master monitor of the optical module200may further include an optical line terminal (OLT).

A bidirectional signal transmission channel is established between the remote server1000and the local information processing device2000through the optical fiber101, the optical module200, the optical network terminal100, and the network cable103.

FIG.2is a structural diagram of an optical network terminal, in accordance with some embodiments. In order to clearly show a connection relationship between the optical module200and the optical network terminal100,FIG.2only shows a structure of the optical network terminal100that is related to the optical module200. As shown inFIG.2, the optical network terminal100further includes a circuit board105disposed in the housing, a cage106disposed on a surface of the circuit board105, a heat sink107disposed on the cage106, and an electrical connector disposed inside the cage106. The electrical connector is configured to connect to the electrical port of the optical module200. The heat sink107has protruding portions such as fins for increasing a heat dissipation area.

The optical module200is inserted into the cage106of the optical network terminal100, and the optical module200is fixed by the cage106. Heat generated by the optical module200is conducted to the cage106and is then dissipated through the heat sink107. After the optical module200is inserted into the cage106, the electrical port of the optical module200is connected to the electrical connector inside the cage106, so that a bidirectional electrical signal connection is established between the optical module200and the optical network terminal100. In addition, the optical port of the optical module200is connected to the optical fiber101, so that a bidirectional optical signal connection is established between the optical module200and the optical fiber101.

FIG.3is a structural diagram of an optical module, in accordance with some embodiments.FIG.4is an exploded view of an optical module, in accordance with some embodiments.FIG.5is a structural diagram of an optical module with an upper shell and a lower shell removed, in accordance with some embodiments.FIG.6is a structural diagram of an optical module with an upper shell, a lower shell, and a protective cover removed, in accordance with some embodiments. As shown inFIGS.3to6, the optical module200includes a shell, and a circuit board300, a silicon photonic chip400, and a laser assembly500that are disposed inside the shell.

The shell includes an upper shell201and a lower shell202. The upper shell201covers on the lower shell202to form the shell with two openings. An outer contour of the shell is generally in a cuboid shape.

In some embodiments of the present disclosure, the lower shell202includes a bottom plate2021and two lower side plates2022that are located on two sides of the bottom plate2021and disposed perpendicular to the bottom plate2021. The upper shell201includes a cover plate2011, and the cover plate2011covers the two lower side plates2022of the lower shell202to form the shell.

In some embodiments, the lower shell202includes a bottom plate2021and two lower side plates2022that are located on two sides of the bottom plate2021and disposed perpendicular to the bottom plate2021; the upper shell201includes a cover plate2011and two upper side plates2012that are located on two sides of the cover plate2011and disposed perpendicular to the cover plate2011. The two upper side plates2012are combined with the two lower side plates2022, respectively, so as to achieve a result that the upper shell201covers the lower shell202.

A direction in which a connection line between the two openings204and205extends may be the same as a longitudinal direction of the optical module200, or may not be the same as the longitudinal direction of the optical module200. For example, the opening204is located at an end (a right end inFIG.3) of the optical module200, and the opening205is also located at an end (a left end inFIG.3) of the optical module200. Alternatively, the opening204is located at an end of the optical module200, while the opening205is located at a side of the optical module200. The opening204is the electrical port, and a connecting finger301of the circuit board300extends out from the electrical port204, and is inserted into the master monitor (e.g., the optical network terminal100). The opening205is the optical port, and is configured to connect to an external optical fiber101, so that the external optical fiber101is connected to the silicon photonic chip400in the optical module200.

With an assembly manner of combining the upper shell201with the lower shell202, it may be easier to install the circuit board300, the silicon photonic chip400, and the laser assembly500into the shell, and the upper shell201and the lower shell202may provide sealing and protection for these components. In addition, during the assembly of the circuit board30, the silicon photonic chip400, and the laser assembly500, it may be easier to arrange the positioning elements, heat dissipation elements, and electromagnetic shielding elements of these components, which facilitates the implementation of automated production.

In some embodiments, the upper shell201and the lower shell202are generally made of a metallic material, which helps achieve electromagnetic shielding and heat dissipation.

In some embodiments, the optical module200further includes an unlocking component203located outside of the shell. The unlocking component203is configured to implement a fixed connection between the optical module200and the master monitor, or to release the fixed connection between the optical module200and the master monitor.

For example, the unlocking component203is located on outer walls of the two lower side plates2022of the lower shell202, and has an engagement element that is matched with the cage of the master monitor (e.g., the cage106of the optical network terminal100). When the optical module200is inserted into the cage of the master monitor, the optical module200is fixed in the cage of the master monitor by the engagement element of the unlocking component203. When the unlocking component203is pulled, the engagement element of the unlocking component203moves along with the unlocking component, and then a connection relationship between the engagement element and the master monitor is changed to release the engagement between the optical module200and the master monitor, so that the optical module200is pulled out of the cage of the master monitor.

The circuit board300includes circuit traces, electronic elements and chips. Through the circuit traces, the electronic elements and the chips are connected together according to circuit design, so as to implement power supply, electrical signal transmission, and grounding functions. The electronic elements may include, for example, a capacitor, a resistor, a triode, and a metal-oxide-semiconductor field-effect transistor (MOSFET). The chips may include, for example, a microcontroller unit (MCU), a limiting amplifier, a clock and data recovery (CDR) chip, a power management chip, or a digital signal processing (DSP) chip.

The circuit board300is generally a rigid circuit board. Since it is made of a relatively hard material, the rigid circuit board may also have a support function. For example, the rigid circuit board may stably support the electronic elements and the chips. The rigid circuit board may also be inserted into the electrical connector in the cage106of the master monitor.

The circuit board300further includes a connecting finger301formed on an end surface thereof, and the connecting finger301is composed of a plurality of independent pins. The circuit board300is inserted into the cage106, and is conductively connected to the electrical connector in the cage106through the connecting finger301. The connecting finger301may be disposed on only one surface (e.g., an upper surface shown inFIG.4) of the circuit board300, or may be disposed on both upper and lower surfaces of the circuit board300to adapt to an occasion where a large number of pins are needed. The connecting finger301is configured to establish an electrical connection with the master monitor to implement power supply, grounding,120signal transmission, data signal transmission, and other functions.

Of course, flexible circuit boards are also used in some optical modules. A flexible circuit board is generally used in conjunction with a rigid circuit board to serve as a supplement for the rigid circuit board.

It will be understood that the silicon photonic chip400and the laser assembly500need to be electrically connected to the circuit board300. For example, the silicon photonic chip400and the laser assembly500are electrically connected to the circuit board300through a wire bonding process, and connection wires between the circuit board300and both of the silicon photonic chip400and the laser assembly500are gold wires.

During shell encapsulation of the optical module200or during use of the optical module200, since the gold wires are very thin and fragile (due to a small diameter) and the distance between the wires is very small (due to high-density wiring), the gold wires are very prone to deformation, damage, or collapse, which may lead to short circuits, open circuits, and other problems.

Based on this, in some embodiments, as shown inFIG.5, the optical module200further includes a protective cover900. The protective cover900is configured to protect the electrical connection wires between the circuit board300and both of the silicon photonic chip400and the laser assembly500. For example, the protective cover900covers the circuit board300and forms a sealed space with the circuit board300, and the silicon photonic chip400, the wiring region of the silicon photonic chip400, the laser assembly500, and the wiring region of the laser assembly500are all encapsulated in the sealed space.

It will be noted that the description “encapsulated in the sealed space” means that, in the sealed space formed by the protective cover900and the circuit board300, the silicon photonic chip400, the wiring region of the silicon photonic chip400, the laser assembly500, and the wiring region of the laser assembly500are in clearance fit with the protective cover900.

The silicon photonic chip400itself has no light source, and the laser assembly500is used as an external light source for the silicon photonic chip400. A laser box may be adopted as the laser assembly500; a laser chip is encapsulated in the laser box; the laser chip emits light, and the laser assembly500is used to provide a laser beam to the silicon photonic chip400.

FIG.11is an exploded view of a substrate, a silicon photonic chip and a laser assembly in an optical module, in accordance with some embodiments, andFIG.24is a structural diagram of a laser assembly in an optical module, in accordance with some embodiments. As shown inFIGS.11and24, the laser assembly500includes a laser upper cover503, and at least one laser chip510, at least one spacer520, at least one collimating lens530, at least one isolator540, and at least one converging lens550that are covered by the laser upper cover503.

The numbers of the laser chips510, the spacers520, the collimating lenses530, the isolators540, and the converging lenses550are not limited in the embodiments of the present disclosure, each of which may be one or more. For example,FIGS.11and24show an example where there are two laser chips510, two spacers520, two collimating lenses530, one isolator540, and two converging lenses550.

The two laser chips510are a first laser chip510A and a second laser chip5108. The two spacers520are a first spacer520A and a second spacer520B. The two collimating lenses530are a first collimating lens530A and a second collimating lens530B. The two converging lenses550are a first converging lens550A and a second converging lens550B.

The first laser chip510A is disposed on a surface of the first spacer520A, and the first collimating lens530A, the isolator540and the first converging lens550A are sequentially disposed in a laser exit direction of the first laser chip510A. The second laser chip5108is disposed on a surface of the second spacer520B, and the second collimating lens530B, the isolator540and the second converging lens550B are sequentially disposed in a laser exit direction of the second laser chip5108. Two laser beams emitted by the two laser chips510share one isolator540.

The laser beam emitted by the first laser chip510A is converted into a collimated laser beam by the first collimating lens530A, and the collimated laser beam may maintain small optical power attenuation during transmission of the beam over a long distance. The collimated laser beam enters the first converging lens550A through the isolator540, and is converted into a converged laser beam by the first converging lens550A, and then the converged laser beam is coupled into the silicon photonic chip400. Similarly, the laser beam emitted by the second laser chip5108is converted into a collimated laser beam by the second collimating lens530B; the collimated laser beam enters the second converging lens550B through the isolator540, and is converted into a converged laser beam by the second converging lens550B, and then the converged laser beam is coupled into the silicon photonic chip400.

The silicon photonic chip400is optically connected to the laser assembly500. The laser beam emitted by the laser assembly500enters the silicon photonic chip400, and the silicon photonic chip400receives the laser beam from the laser assembly500. In some embodiments, the laser assembly500provides a laser beam with a single wavelength, stable power, and no information to the silicon photonic chip400, and the silicon photonic chip400modulates the laser beams, so as to load the data to be transmitted into the laser beam to form an optical signal. In addition, the silicon photonic chip400also receives an optical signal from an outside of the optical module200, and converts the optical signal into a current signal to extract data from the optical signal. That is, both the modulation of the laser beam emitted by the optical module200and the demodulation of the optical signal received by the optical module200are completed by the silicon photonic chip400.

In some embodiments, as shown inFIG.6, the optical module200further includes a transimpedance amplifier330and a laser driver chip340that are disposed on the silicon photonic chip400. The transimpedance amplifier330is configured to convert the current signal output by the silicon photonic chip400into a voltage signal, and the laser driver chip340is configured to provide a modulation signal to the silicon photonic chip400.

A process in which the optical module200implements the interconversion between the optical signal and the electrical signal is described as follows. The electrical signal from the master monitor is transmitted to a digital signal processing chip through the connecting finger301of the circuit board300, and is then transmitted to the laser driver chip340after being processed by the digital signal processing chip; the silicon photonic chip400receives a laser beam carrying no information that is output by the laser assembly500, and modulates the received laser beam according to the modulation signal output by the laser driver chip340to form an optical signal; and then the optical signal is sent to the outside of the optical module200, thereby realizing the conversion from the electrical signal into the optical signal. The optical signal from the outside of the optical module200is converted into a current signal through the silicon photonic chip400, the current signal is converted into a differential voltage signal by the transimpedance amplifier330, and the differential voltage signal is output to the master monitor through the connecting finger301of the circuit board300after being processed by the digital signal processing chip, thereby realizing the conversion of the optical signal into the electrical signal.

As shown inFIGS.5and6, the optical module200further includes an optical fiber interface800and two internal optical fiber ribbons600. The two internal optical fiber ribbons600are a first internal optical fiber ribbon601and a second internal optical fiber ribbon602, and the first internal optical fiber ribbon601and the second internal optical fiber ribbon602are thin flat ribbons formed by a plurality of internal optical fibers arranged in parallel and cured by ultraviolet light.

In some embodiments of the present disclosure, the first internal optical fiber ribbon601is an emitting optical fiber ribbon, and the second internal optical fiber ribbon602is a receiving optical fiber ribbon. An end of the first internal optical fiber ribbon601is connected to the silicon photonic chip400, and another end thereof is connected to the optical fiber interface800. An end of the second internal optical fiber ribbon602is connected to the silicon photonic chip400, and another end thereof is connected to the optical fiber interface800. The optical fiber interface800is configured to be connected to the external optical fiber101. It will be seen that the silicon photonic chip400is optically connected to the external optical fiber101through the first internal optical fiber ribbon601, the second internal optical fiber ribbon602, and the optical fiber interface800.

To ensure the stability of relative positions between the silicon photonic chip400and both of the first internal optical fiber ribbon601and the second internal optical fiber ribbon602, and thus ensure a coupling efficiency of the silicon photonic chip400and both of the first internal optical fiber ribbon601and the second internal optical fiber ribbon602, in some embodiments, it is arranged that the optical module200further includes two optical fiber ribbon connectors700, and the two optical fiber ribbon connectors700are a first optical fiber ribbon connector701and a second optical fiber ribbon connector702. The first optical fiber ribbon connector701is configured to clamp the end of the first internal optical fiber ribbon601that is connected to the silicon photonic chip400, and the second optical fiber ribbon connector702is configured to clamp the end of the second internal optical fiber ribbon602that is connected to the silicon photonic chip400.

The laser assembly500transmits the laser beam carrying no information to the silicon photonic chip400, the silicon photonic chip400modulates the laser beam carrying no information to form an optical signal, and the optical signal is transmitted to the external optical fiber101through the first internal optical fiber ribbon601and the optical fiber interface800. The optical signal from the external optical fiber101is transmitted to the silicon photonic chip400through the optical fiber interface800and the second internal optical fiber ribbon602. In this way, it is realized that the optical module200outputs the optical signal to the external optical fiber101or receives the optical signal from the external optical fiber101.

FIG.12is a structural diagram of a silicon photonic chip in an optical module, in accordance with some embodiments. In some embodiments of the present disclosure, in order to make it easier for the silicon photonic chip to receive and transmit optical signals, as shown inFIG.12, it is arranged that the silicon photonic chip400includes a first optical waveguide end surface401, a second optical waveguide end surface402, and a third optical waveguide end surface403that are disposed on a laser incident surface thereof, and each optical waveguide end surface has at least one optical channel. For example, as shown inFIG.12, the first optical waveguide end surface401has two optical channels, the second optical waveguide end surface402has four optical channels, and the third optical waveguide end surface403has four optical channels.

It will be noted that, a laser exit surface of the laser assembly500is the surface of the laser assembly500proximate to the silicon photonic chip400, and the laser incident surface of the silicon photonic chip400is a surface of the silicon photonic chip400proximate to the laser assembly500.

The first optical waveguide end surface401is optically connected to the laser assembly500, and is configured to receive the laser beam carrying no information emitted by the laser assembly500. The second optical waveguide end surface402is connected to an end of the first internal optical fiber ribbon601, and is configured to transmit an optical signal obtained after modulation by the silicon photonic chip400to the outside of the optical module200. The third optical waveguide end surface403is coupled to an end of the second internal optical fiber ribbon602, and is configured to receive the optical signal from the outside of the optical module200.

The laser assembly500provides a laser beam carrying no information to the silicon photonic chip400, and the laser beam carrying no information enters the silicon photonic chip400through the first optical waveguide end surface401. The silicon photonic chip400modulates the received laser beam carrying no information to form an optical signal, and the optical signal is transmitted to the first internal optical fiber ribbon601through the second optical waveguide end surface402, and is then transmitted to the outside of the optical module200through the first internal optical fiber ribbon601and the optical fiber interface800. The optical signal from the outside of the optical module200is transmitted to the third optical waveguide end surface403through the optical fiber interface800and the second internal optical fiber ribbon602, and is then transmitted into the silicon photonic chip400through the third optical waveguide end surface403. In this way, it is realized that the silicon photonic chip400outputs the optical signal to the outside of the optical module200and receives the optical signal from the outside of the optical module200.

In order to realize the above modulation and demodulation processes of the optical signal, the circuit board300, the silicon photonic chip400, and the laser assembly500need to be assembled according to their predetermined positions, so as to form a predetermined optical propagation path.

Since the optical path is very sensitive to a positional relationship between the silicon photonic chip400and the laser assembly500, materials with different thermal expansion coefficients will deform to different degrees, which is not conducive to implementing a predetermined optical path. In some embodiments of the present disclosure, the optical module200further includes a substrate302. The silicon photonic chip400and the laser assembly500are disposed on the same substrate302, and the substrate302is a plate-shaped structure made of a same material. The substrate302made of the same material is deformed identically when heated; therefore, the deformation of the substrate302has a same impact on the silicon photonic chip400and the laser assembly500, which may avoid a change in the relative position between the silicon photonic chip400and the laser assembly500.

A material of the substrate302is not limited in some embodiments of the present disclosure. For example, the material of the substrate302includes tungsten copper or aluminum nitride ceramic. For example, the thermal expansion coefficient of the material of the substrate302is close to that of the silicon photonic chip400and/or the laser assembly500. For example, a main material of the silicon photonic chip400is silicon, the laser assembly500is made of KOVAR® alloy, and the substrate302is made of silicon or glass. KOVAR® alloy, also known as iron-nickel-cobalt alloy or iron-nickel-cobalt glass sealing alloy, generally contains 29% of nickel and 18% of cobalt, and the rest is iron. Due to the addition of cobalt, the thermal expansion coefficient of KOVAR® alloy is reduced and becomes close to that of glass, which makes KOVAR® alloy suitable for sealing to glass.

It will be seen from the above that the silicon photonic chip400and the laser assembly500are generally disposed on a same side of the circuit board300. In this case, the positional relationship between the substrate302and the circuit board300varies.

FIG.7is a structural diagram of a circuit board in an optical module, in accordance with some embodiments.FIG.20is a structural diagram of another circuit board in an optical module, in accordance with some embodiments.FIG.21is an assembly diagram of another substrate and a circuit board in an optical module, in accordance with some embodiments.FIG.22is a top view showing a relative relationship between a signal pad and other structures in an optical module, in accordance with some embodiments. As shown inFIGS.7and20to22, the circuit board300includes a groove disposed on a surface thereof, and the groove may be a through hole303penetrating upper and lower surfaces of the circuit board300or a blind hole310not penetrating the upper and lower surfaces of the circuit board300. The substrate302is disposed in the groove, and the silicon photonic chip400and the laser assembly500are disposed on a surface of the substrate302. In this way, it may not only be possible to avoid a change in the relative position between the silicon photonic chip400and the laser assembly500, but it may also be possible to facilitate the electrical connection between the circuit board300and both of the silicon photonic chip400and the laser assembly500. In addition, the silicon photonic chip400and the laser assembly500may dissipate heat to the substrate302; therefore, the substrate302may have both supporting and heat dissipating effects.

The number of the substrates302and the number of the grooves are not limited in some embodiments of the present disclosure, each of which may be one or more. For example,FIG.7shows one substrate302and one groove. For example,FIG.21shows two substrates302and two grooves, with each substrate302disposed in a corresponding groove. A description will be given below by taking an example where only one substrate302and only one groove are provided.

It will be noted that, in a case where the components are applied to an optical module with a high transmission rate, such as 800 Gb/s, the number of each component of the optical module200, for example, the silicon photonic chip400, the laser assembly500, the substrate302, and the groove, is two; in a case where the components are applied to a 400 Gb/s optical module, the number of each component of the optical module200, for example, the silicon photonic chip400, the laser assembly500, the substrate302, and the groove, is one.

In some embodiments, as shown inFIG.7, the groove is a though hole303penetrating the upper and lower surfaces of the circuit board300, the substrate302is disposed in the through hole303, and the silicon photonic chip400and the laser assembly500are disposed on a surface of the substrate302.FIG.8is a structural diagram of a substrate in an optical module, in accordance with some embodiments, andFIG.9is a structural diagram of a substrate in an optical module from another angle, in accordance with some embodiments. As shown inFIGS.8and9, the substrate302is an integrated structure. The substrate302includes a body3020, a first support step3027, and a second support step3028, and the first support step3027and the second support step3028are disposed at two opposite ends of the body3020. The body3020includes four clamping portions, which are a first clamping portion3021, a second clamping portion3022, a third clamping portion3023and a fourth clamping portion3024, respectively. The second clamping portion3022, the third clamping portion3023and the fourth clamping portion3024are arranged side by side, and the first clamping portion3021is disposed at ends of the second clamping portion3022, the third clamping portion3023and the fourth clamping portion3024that are proximate to the connecting finger301of the circuit board300.

The body3020further includes a first gap3025and a second gap3026. The first gap3025is disposed between the second clamping portion3022and the fourth clamping portion3024, and the second gap3026is disposed between the second clamping portion3022and the third clamping portion3023. The first gap3025and the second gap3026are configured to fix the laser upper cover503. The body3020has a first side surface30201and a second side surface30202that are disposed opposite each other, and a third side surface30203and a fourth side surface30204that are disposed opposite each other. The first support step3027is disposed around the first side surface30201, and parts of the third side surface30203and the fourth side surface30204. The second support step3028is disposed around the second side surface30202, and parts of the third side surface30203and the fourth side surface30204. The first support step3027and the second support step3028may be protruding structures.

The body3020is embedded in the through hole303of the circuit board300, and the first support step3027and the second support step3028support the circuit board300. A distance from an upper surface (a surface proximate to the cover plate2011) of the body3020to an upper surface (a surface proximate to the cover plate2011) of the first support step3027or the second support step3028is equal to a thickness of the circuit board300. In addition, to enhance the reliability of a connection between the substrate302and the circuit board300, an adhesive may be used to fix the first support step3027and the second support step3028of the substrate302to the circuit board300. That is, the upper surface of the first support step3027and the upper surface of the second support step3028are fixed to a lower surface (a surface away from the cover plate2011) of the circuit board300by an adhesive.

FIG.10is an assembly diagram of a substrate, a silicon photonic chip and a laser assembly in an optical module, in accordance with some embodiments, andFIG.11is an exploded view of a substrate, a silicon photonic chip and a laser assembly in an optical module, in accordance with some embodiments. As shown inFIGS.6,10and11, the silicon photonic chip400is disposed on a surface of the first clamping portion3021, and the transimpedance amplifier330and the laser driver chip340are disposed on a surface of the silicon photonic chip400away from the first clamping portion3021. The laser assembly500is disposed on a surface of the second clamping portion3022, the first optical fiber ribbon connector701is disposed on a surface of the third clamping portion3023, and the second optical fiber ribbon connector702is disposed on a surface of the fourth clamping portion3024.

The laser upper cover503of the laser assembly500covers the second clamping portion3022, and forms a sealed space with the second clamping portion3022. The laser chip510, the spacer520, the collimating lens530, the isolator540, and the converging lens550are all disposed on the second clamping portion3022and are located in the sealed space formed by the laser upper cover503and the second clamping portion3022, so that the above components are prevented from being contaminated or damaged.

The laser upper cover503includes a laser cover plate5033, and a first side plate5031and a second side plate5032that are connected to the laser cover plate5033and disposed opposite each other. The first side plate5031is inserted into the first gap3025of the substrate302, and the second side plate5032is inserted into the second gap3026of the substrate302. An end of the laser cover plate5033away from the silicon photonic chip400extends beyond the first side plate5031and the second side plate5032, and is bridged over the circuit board300. That is, the circuit board supports the laser cover plate5033. The laser upper cover503is configured to protect the various components of the laser assembly500, such as the laser chip510, the spacer520, the collimating lens530, the isolator540, the converging lens550, and the wiring region of the laser assembly500.

The laser assembly500is mounted on the second clamping portion3022. For example, the laser assembly500is connected to the circuit board300by a wire bonding process.

Since the circuit board300is disposed on the first support step3027and the second support step3028of the substrate302through the through hole303, a surface of the substrate302facing away from the silicon photonic chip400and the laser assembly500is in contact with the shell (e.g., the lower shell202) of the optical module200. Therefore, the heat inside the optical module200may be transmitted to the shell of the optical module200through the substrate302and then conducted to the outside of the optical module200, which avoids the accumulation of heat inside the optical module200. Meanwhile, the various components of the laser assembly500, such as the laser chip510, the spacer520, the collimating lens530, the isolator540and the converging lens550are disposed on the substrate302and are wrapped by the laser upper cover503, which saves an encapsulation space of the laser assembly500and facilitates the encapsulation of the laser assembly500.

FIG.13is an assembly diagram of a substrate and a circuit board in an optical module, in accordance with some embodiments;FIG.14is an assembly diagram of a substrate and a circuit board in an optical module from another angle, in accordance with some embodiments;FIG.15is an exploded view of a substrate and a circuit board in an optical module, in accordance with some embodiments; andFIG.16is a cross-sectional view of a substrate and a circuit board that have been assembled in an optical module, in accordance with some embodiments.

As shown inFIGS.13to16, the circuit board300further includes a first metal layer305and a second metal layer306. The first metal layer305and the second metal layer306are disposed on the lower surface of the circuit board300, and correspond to positions of the first support step3027and the second support step3028, respectively. The first metal layer305and the second metal layer306are configured to be connected to the substrate302and a ground layer of the circuit board300. The first metal layer305is connected to the ground layer of the circuit board300, and the first metal layer305is connected to the first support step3027of the substrate302. The second metal layer306is connected to the ground layer of the circuit board300, and the second metal layer306is connected to the second support step3028of the substrate302.

For example, the ground layer of the circuit board300is disposed inside the circuit board300, and the first metal layer3027and the second metal layer3028are connected to the ground layer of the circuit board300through via holes.

In the optical module200, the silicon photonic chip400is disposed on the substrate302. In a case where the substrate302is made of a non-conductive material, such as aluminum nitride ceramic, the silicon photonic chip400is connected to the ground layer of the circuit board300through a connection wire, such as a gold wire, so that the silicon photonic chip400is grounded.

In a case where the substrate302is made of a conductive material, such as tungsten copper, the silicon photonic chip400is electrically connected to the first metal layer306and the second metal layer307through the substrate302, and the first metal layer306and the second metal layer307are electrically connected to the ground layer of the circuit board300. In this way, the silicon photonic chip400is grounded through the substrate302, which avoids the parasitic inductance caused by a grounding connection of the silicon photonic chip400through the gold wire, and ensures the quality of signal transmission.

FIG.17is a top view of a substrate in an optical module, in accordance with some embodiments;FIG.18is a structural diagram of a metal layer laid on an outer periphery of a through hole of a circuit board in an optical module, in accordance with some embodiments; andFIG.19is a diagram showing a relative positional relationship between support steps of a substrate and metal layers laid on an outer periphery of a through hole in an optical module, in accordance with some embodiments. As shown inFIGS.17to19, a shape of the first metal layer305of the circuit board300is the same as a shape of the first support step3027of the substrate302, and a shape of the second metal layer306of the circuit board300is the same as a shape of the second support step3028of the substrate302.

The through hole303has a first side3031and a second side3032that are disposed opposite each other, and a third side3033and a fourth side3034that are disposed opposite each other. For example, the first support step3027is disposed around the first side surface30201, and parts of the third side surface30203and the fourth side surface30204of the body3020of the substrate302, and the first metal layer305is disposed around the first side3031, and parts of the third side3033and the fourth side3034of the through hole303. The second support step3028is disposed around the second side surface30202, and parts of the third side surface30203and the fourth side surface30204of the body3020, and the second metal layer306is disposed around the second side3032, and parts of the third side3033and the fourth side3034of the through hole303.

In some embodiments of the present disclosure, the first support step3027and the first metal layer305are connected by conductive silver paste, and the second support step3028and the second metal layer305are connected by conductive silver paste.

FIG.23is an enlarged view showing a relative relationship between a signal pad and other structures in an optical module, in accordance with some embodiments, andFIG.24is a structural diagram of a laser assembly in an optical module, in accordance with some embodiments. As shown inFIGS.20,21,22,23, and24, the groove is a blind hole310disposed in the upper surface (the surface proximate to the cover plate2011) of the circuit board300; the blind hole310does not penetrate the upper and lower surfaces of the circuit board300, and a bottom surface of the blind hole310can be seen in a top view thereof. The substrate302is embedded in the blind hole310, and the silicon photonic chip400and the laser assembly500are disposed on the surface of the substrate302. For an optical module with a high transmission rate and a large number of electronic components, the provision of the blind hole310makes it possible for the electronic components to be arranged in a region on the lower surface of the circuit board300corresponding to the blind hole310, and for the wiring of the inner layers of the circuit board to be arranged in a region between the bottom of the blind hole310and the lower surface of the circuit board300.

In some embodiments of the present disclosure, a surface of the silicon photonic chip400proximate to the cover plate2011is flush with a surface of the circuit board300proximate to the cover plate2011, and a surface of the laser assembly500proximate to the cover plate2011is flush with the surface of the circuit board300proximate to the cover plate2011. With this arrangement, a length of connection wires of the silicon photonic chip400and the laser assembly500may be shortened.

The blind hole310includes a metal layer316disposed on a bottom surface thereof, and the metal layer316may be, for example, a copper layer or an aluminum layer. A description will be given below by taking an example where the metal layer316is a copper layer.

The copper layer316is configured to transfer heat conducted from the silicon photonic chip400and the laser assembly500to the substrate302to the shell of the optical module200, so as to facilitate the heat dissipation of the optical module200and avoid heat accumulation inside the optical module200. The blind hole310further includes a signal pad315disposed on the bottom surface thereof, and the signal pad315is configured to be connected to the silicon photonic chip400through a connection wire.

The circuit board300includes a ground layer and a signal layer, the copper layer316is connected to the ground layer through a via hole, and the signal pad315is connected to the signal layer through a via hole.

As shown inFIGS.21,22, and23, the substrate302includes four thermal pads arranged separately, which are a first thermal pad3041, a second thermal pad3042, a third thermal pad3043, and a fourth thermal pad3044.

The second thermal pad3042, the third thermal pad3043, and the fourth thermal pad3044are arranged side by side, and the first thermal pad3041is disposed at ends of the second thermal pad3042, the third thermal pad3043, and the fourth thermal pad3044that are proximate to the connecting finger301of the circuit board300. The silicon photonic chip400is disposed on the first thermal pad3041, the laser assembly500is disposed on the second thermal pad3042, the first optical fiber ribbon connector701is disposed on the third thermal pad3043, and the second optical fiber ribbon connector702is disposed on the fourth thermal pad3044.

The first thermal pad3041, the second thermal pad3042, the third thermal pad3043, and the fourth thermal pad3044are all embedded in the blind hole310and located on the copper layer316. The first thermal pad3041is configured to conduct heat generated by the silicon photonic chip400to the copper layer316of the blind hole310; the second thermal pad3042is configured to conduct heat generated by the laser assembly500to the copper layer316of the blind hole310; the third thermal pad3043is configured to conduct heat on the first internal optical fiber ribbon601to the copper layer316of the blind hole310; and the fourth thermal pad3044is configured to conduct heat on the second internal optical fiber ribbon602to the copper layer316of the blind hole310. The first thermal pad3041, the second thermal pad3042, the third thermal pad3043, and the fourth thermal pad3044may be fixed to the copper layer316of the blind hole310by a thermally conductive adhesive.

In some embodiments of the present disclosure, thermal expansion coefficients of the first thermal pad3021, the second thermal pad3022, the third thermal pad3023, and the fourth thermal pad3024are matched with the thermal expansion coefficients of the silicon photonic chip400, the laser assembly500, the first internal optical fiber ribbon601, and the second internal optical fiber ribbon602, respectively, so as to ensure the stability of the optical path at different temperatures.

The silicon photonic chip400is disposed on the substrate302, and in a case where the thermal pads of the substrate302are made of a non-conductive material, such as aluminum nitride ceramic, the silicon photonic chip400is electrically connected to the ground layer of the circuit board300through a connection wire, such as a gold wire.

In a case where the thermal pads of the substrate302are made of a conductive material, such as tungsten copper, the silicon photonic chip400may be directly electrically connected to the copper layer316of the blind hole310through the substrate302, and the copper layer316is electrically connected to the ground layer of the circuit board300through a via hole. In this way, the silicon photonic chip400is grounded through the substrate302, which avoids the parasitic inductance caused by a grounding connection of the silicon photonic chip400through the gold wire and ensures the quality of signal transmission.

FIG.25is a structural diagram of a circuit board, a silicon photonic chip, and a laser assembly in an optical module, in accordance with some embodiments;FIG.26is a diagram showing a relative positional relationship between a laser upper cover and a circuit board in an optical module, in accordance with some embodiments;FIG.27is a structural diagram of a laser upper cover in an optical module, in accordance with some embodiments; andFIG.28is a structural diagram of a laser upper cover in an optical module from another angle, in accordance with some embodiments. As shown inFIGS.25to28, the laser upper cover503covers the second thermal pad3042and is in contact with the copper layer316. The laser upper cover503and the second thermal pad3042form a sealed space, and the laser chip510, the spacer520, the collimating lens530, the isolator540, and the converging lens550are all disposed on the second thermal pad3042and are located in the sealed space formed by the laser upper cover503and the second thermal pad3042, so that the above components are prevented from being contaminated or damaged.

The laser upper cover503includes a notch5034, a protruding end5035, and a cavity5036. The notch5034is used to avoid the signal pad315of the blind hole310(as shown inFIG.23), just so that the signal pad315is not covered by the laser upper cover503, which facilitates a connection between the silicon photonic chip400and the circuit board300. The protruding end5035is bridged over the circuit board300; that is, the circuit board300supports the protruding end5035and, in turn, supports the laser upper cover503. The cavity5036is used to cover the components such as the laser chip510, the spacer520, the collimating lens530, the isolator540, and the converging lens550on the second thermal pad3042and the wiring region of the laser assembly500.

In this case, the heat generated by the silicon photonic chip400, the laser assembly500, the first internal optical fiber ribbon601, and the second internal optical fiber ribbon602is transferred to the copper layer316of the blind hole310through the thermal pads, respectively. A portion of the heat is transferred to the lower shell202of the optical module200through the circuit board300, and is dissipated through the lower shell202; and another portion of the heat is transferred to the upper shell201of the optical module200through the laser upper cover503, and is dissipated through the upper shell201.

Therefore, the heat inside the optical module200may be transmitted to the shell of the optical module200through the laser upper cover503and the circuit board300, and then the heat is conducted to the outside of the optical module200, which avoids heat accumulation inside the optical module200.

In some embodiments of the present disclosure, the laser upper cover503may be made of a metal material with high thermal conductivity, including tungsten copper and molybdenum copper. To achieve a better heat dissipation effect, a contact area between the laser upper cover503and the copper layer316may be made larger, because the larger the contact area, the better the heat dissipation.

FIG.29is a connection diagram of a silicon photonic chip and a circuit board in an optical module, in accordance with some embodiments. As shown inFIG.29, an end of the silicon photonic chip400away from the laser upper cover503is connected to the circuit board300through a connection wire, so as to achieve high-speed signal transmission between the circuit board300and the silicon photonic chip400; and an end of the silicon photonic chip400proximate to the laser upper cover503is connected to the signal pad315of the blind hole310through a connection wire, so as to achieve low-speed signal transmission between the circuit board300and the silicon photonic chip400. In this way, a signal connection between the silicon photonic chip400and the circuit board300is achieved.

In some embodiments of the present disclosure, the silicon photonic chip400is disposed on the first thermal pad3041instead of the surface of the circuit board300. In this way, it may be possible to shorten a length of the gold wire used for high-frequency signal transmission between the silicon photonic chip400and the circuit board300, and in turn optimize the transmission performance of high frequency signals.

In some embodiments of the present disclosure, the transimpedance amplifier330and the laser driver chip340are flip-chip soldered on the silicon photonic chip400; that is, the surfaces of the transimpedance amplifier330and the laser driver chip340on which the electronic components are disposed face the silicon photonic chip400. The surfaces of the transimpedance amplifier330and the laser driver chip340on which the electronic components are disposed are defined as front surfaces of the transimpedance amplifier330and the laser driver chip340, and the surfaces opposite to the front surfaces are defined as back surfaces; therefore, the back surfaces of the transimpedance amplifier330and the laser driver chip340are immediately adjacent to the upper shell201of the optical module200. In order to achieve the heat dissipation of the transimpedance amplifier330and the laser driver chip340, a heat conduction column may be used to transfer heat between the transimpedance amplifier330and the upper shell201of the optical module200, and a thermally conductive adhesive may also be filled in a gap between the transimpedance amplifier330and the upper shell201of the optical module200to transfer heat; as for the laser driver chip340, the heat conduction column or thermally conductive adhesive may also be used to transfer heat.

Those skilled in the art will understand that the scope of disclosure of the present disclosure is not limited to the embodiments described above, and that modifications and substitutions of certain elements of the embodiments may be made without departing from the spirit of the present disclosure. The scope of the present disclosure is limited by the appended claims.