Pump laser, optical amplification module, and optical amplification system

Abstract

The present application provides a pump laser, an optical amplification module, and an optical amplification system. The pump laser is packaged by using a packaging substrate on which a plurality of LD chips and / or a plurality of PD chips are integrated, so that optical power outputted by the pump laser is increased, and the size and costs of a single pump laser are reduced, thereby facilitating improvement of the optical power amplification capability of the optical amplification module, reducing the size and costs of the optical amplification module, and promoting wide application of the optical amplification module.

Description

Pump laser, optical amplification module and optical amplification system

[0001] This application claims priority to the Chinese patent application No. CN202410545587.8, filed on April 30, 2024, and entitled “Pump laser, optical amplification module and optical amplification system”, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the field of laser, in particular to a pump laser, an optical amplification module and an optical amplification system. BACKGROUND

[0003] Optical network systems generally use one or more optical amplification modules to amplify the optical power of optical signals to compensate for the loss of optical signals during transmission, so as to achieve longer transmission distance and better signal quality. As a pump source for amplifying optical power, the pump laser is a key device in the optical amplification module. To ensure the long-term stable operation of the pump laser, the elements of the pump laser, such as chip on carrier (COC), are packaged in a cavity in the housing, and the housing also has an electrical connector and a fiber tail pipe, and the optical fiber extends from the outside of the housing to the cavity through the fiber tail pipe. The laser diode (LD) chip in the COC receives a driving signal through the electrical connector on the housing and emits laser under the driving of the driving signal, and the laser is output to the outside of the housing through the optical fiber.

[0004] However, with the continuous increase of communication capacity, the optical network system puts forward higher and higher requirements on the optical power amplification capability of the optical amplification module. At the same time, with the rapid development of the communication industry, the demand for reducing the size and cost of the optical amplification module is also more urgent. Therefore, improving the optical power output by a single pump laser on the optical amplification module, and reducing the size and cost of a single pump laser, plays a crucial role in the wide application of the optical amplification module. SUMMARY

[0005] The present application provides a pump laser, an optical amplification module and an optical amplification system, which uses a packaging substrate integrating multiple chips to package the pump laser, improves the optical power output by the pump laser, and reduces the size and cost of a single pump laser, thereby facilitating the improvement of the optical power amplification capability of the optical amplification module, the reduction of the size and cost of the optical amplification module, and the promotion of the wide application of the optical amplification module.

[0006] In a first aspect, the present application provides a pump laser, which comprises a shell having a cavity inside, a packaging substrate and a plurality of optical fibers, the shell has an electrical connector and a fiber tail pipe, the packaging substrate is assembled in the cavity, the plurality of optical fibers respectively extend from outside of the shell to inside of the cavity via the fiber tail pipe; a plurality of laser diode (LD) chips are integrated on the packaging substrate, the plurality of LD chips are electrically connected to the electrical connector through the packaging substrate, the plurality of LD chips are configured to respectively receive a driving signal from the electrical connector and emit a plurality of laser beams under the driving of the driving signal; end faces of the plurality of optical fibers are respectively located on optical paths of the plurality of laser beams, and the plurality of optical fibers are configured to transmit the plurality of laser beams to outside of the shell.

[0007] The present application proposes that a packaging substrate integrated with a plurality of LD chips (referred to as a multi-chip substrate) is installed in the cavity of the pump laser. Compared with a plurality of packaging substrates each integrated with a single LD chip (referred to as a single-chip substrate), the multi-chip substrate not only helps to reduce the packaging steps, reduce the assembly accuracy requirement of the packaging substrate, improve the packaging yield and reduce the packaging cost, but also helps to integrate more LD chips in the limited size cavity, improve the maximum power of the laser output by the laser, reduce the bearing pressure of the single LD chip and reduce the failure rate of the single LD chip, thereby improving the reliability of the laser. In addition, the multi-chip substrate has a larger area than the single-chip substrate, which not only helps to dissipate heat from the chips, but also helps to reduce the stress on the LD chips in subsequent packaging and improve the reliability of the LD chips.

[0008] Optionally, the packaging substrate is integrated with 3 or more than 3 LD chips, or the plurality of LD chips are 3 or more than 3 LD chips, or the number of LD chips in the plurality of LD chips is greater than or equal to 3.

[0009] Optionally, the multi-chip substrate has a plurality of pads, the plurality of LD chips are connected to the plurality of pads through an electrical interconnection structure in the multi-chip substrate, and the plurality of pads are electrically connected to the electrical connector. In this way, it is helpful to avoid connecting the multi-chip substrate to the electrical connector through other substrates, thereby reducing the number of substrates in the cavity to reduce the cost and the size of the shell. In order to distinguish, the pads connected to the LD chips on the multi-chip substrate are referred to as LD pads hereinafter.

[0010] The present application does not limit the way in which the pads are electrically connected to the electrical connector, for example, the pads can be electrically connected to the electrical connector by bonding or welding. The present application does not limit the material of the bonding wire used for bonding, for example, the bonding wire can be a metal wire.

[0011] Optionally, the plurality of LD pads are located in the area between the plurality of LD chips and the electrical connector of the package. Compared with assembling all or part of the plurality of LD pads in the area between different LD chips, the length of the electrical connection line between the LD pads and the electrical connector is shortened, the electrical loss and the wiring complexity are reduced, the reliability of the electrical connection line is improved, and the current-carrying capacity of the electrical connection line is improved.

[0012] Optionally, the plurality of optical fibers are fixed on the multi-core substrate. For the convenience of description, the area of the multi-core substrate for fixing the optical fibers is referred to as the optical fiber fixing area. Compared with fixing the plurality of optical fibers on other substrates, the number of substrates in the cavity is reduced, the cost is reduced, and the size of the package is reduced.

[0013] Optionally, the multi-core substrate has a plurality of limiting mechanisms for fixing the plurality of optical fibers, and the end faces of the plurality of optical fibers fixed by the plurality of limiting mechanisms are located on the light paths of the laser emitted by the plurality of LD chips. After the plurality of LD chips are integrated on the multi-core substrate, the positions of the light paths of the laser emitted by each of the plurality of LD chips relative to the multi-core substrate are fixed. The plurality of limiting mechanisms can be prepared according to the positions of the light paths of the plurality of LD chips on the multi-core substrate, so that the end faces of the plurality of optical fibers fixed by the plurality of limiting mechanisms are located on the plurality of light paths. In this way, as long as the plurality of optical fibers are installed in the plurality of limiting mechanisms, the coupling between the LD chips and the optical fibers can be realized, thereby facilitating the reduction of the difficulty of active coupling, and even avoiding the need to find the installation positions of the optical fibers on the multi-core substrate through active coupling, thereby facilitating the reduction of the assembly difficulty and the assembly cost.

[0014] Optionally, a plurality of grooves are processed on the multi-core substrate to form the plurality of limiting mechanisms, and the plurality of optical fibers are respectively installed in the plurality of grooves. This is advantageous for more stable fixing of the optical fibers on the multi-core substrate and improves the reliability of the laser. Since the optical fibers are fixed in the grooves, the coupling between the end faces of the optical fibers fixed in the grooves and the LD chips can be facilitated by processing a plurality of grooves in the projection area of the plurality of light paths on the multi-core substrate, the coupling efficiency of the optical signals between the LD chips and the optical fibers is improved, the difficulty of finding the processing positions of the limiting mechanisms on the multi-core substrate is reduced, and the implementability of the scheme is improved.

[0015] The present application does not limit the shape of the groove. For example, the groove can be a V-shaped groove, a square groove, a trapezoidal groove, a semicircular groove, or the like.

[0016] The present application does not limit the depth of the groove. After the optical fiber is installed in the groove, all or part of the optical fiber is located in the groove.

[0017] The present application does not limit the fixing position of the optical fiber in the groove. For example, the optical fiber can be fixed on one or more surfaces in the groove.

[0018] The application does not limit the fixing mode between the optical fiber and the groove, for example, the optical fiber can be fixed on the surface of the groove by welding or sticking, etc.

[0019] Optionally, based on the fact that the plurality of optical fibers are adhered on the multi-core substrate by the adhesive respectively, the multi-core substrate has a groove between the region for adhering the plurality of optical fibers and the plurality of LD chips, so that it is beneficial to prevent the adhesive from spreading to the chip end face in the process of adhering the optical fiber on the multi-core substrate, thereby avoiding the influence of the adhesive overflow on the optical path or the LD chip, affecting the transmission of the optical signal, and even causing the adhesive to overheat and damage the device.

[0020] The application does not limit the type of adhesive, for example, the adhesive can be glue or glass solder or metal solder, etc.

[0021] Optionally, in order to improve the reliability of the laser, a temperature detection element can be integrated in the cavity to detect the temperature in the cavity, which is beneficial to keep the temperature in the cavity within the working temperature range of the LD chip, thereby improving the reliability of the LD chip. In addition, the temperature detection element can be integrated on the multi-core substrate, and the multi-core substrate is connected to the electrical connector, compared with the temperature detection element integrated on other substrates, it is beneficial to reduce the number of substrates in the cavity, thereby reducing the cost and the size of the tube shell.

[0022] Optionally, a plurality of PD chips can be integrated in the cavity, and the plurality of PD chips are used to detect the intensity and / or wavelength of the optical signal emitted by the plurality of LD chips, which is beneficial to monitor the working state of the LD chip.

[0023] Optionally, the plurality of PD chips can be integrated on the same packaging substrate (referred to as PD substrate). Compared with the plurality of packaging substrates respectively mounting a single PD chip, it is not only beneficial to reduce the packaging steps, reduce the requirement for the assembly accuracy of the packaging substrate, improve the packaging yield, and reduce the packaging cost, but also beneficial to save the space in the cavity, thereby facilitating the integration of more LD chips in the cavity with limited size, and improving the maximum power of the laser output by the laser. In addition, the packaging substrate integrated with a plurality of PD chips has a larger area than the packaging substrate integrated with a single PD chip, which is not only beneficial to the heat dissipation of the PD chip, but also the larger area of the packaging substrate is beneficial to reduce the stress generated by the subsequent packaging on the PD chip, thereby improving the reliability of the PD chip.

[0024] Optionally, the PD substrate has a plurality of pads (referred to as PD pads), the plurality of PD chips are connected to the plurality of PD pads through the electrical interconnection structure in the PD substrate, and the plurality of PD pads are directly connected to the electrical connector. In this way, it is beneficial to avoid the PD substrate being connected to the electrical connector through other substrates, thereby reducing the number of substrates in the cavity, thereby reducing the cost and the size of the tube shell.

[0025] Optionally, the at least two PD chips are connected in parallel to the same PD pad, so as to reduce the number of PD pads on the PD substrate, reduce the number of electrical connection lines between the PD pads and the electrical connector, and reduce the wiring complexity.

[0026] Optionally, the plurality of PD chips and the plurality of LD chips are integrated on the same packaging substrate, or in other words, the plurality of PD chips are integrated on the above-mentioned multi-chip substrate, or in other words, the PD substrate is the above-mentioned multi-chip substrate, which is beneficial to reduce the number of substrates in the cavity, not only reducing the assembly times and reducing the assembly cost, but also further saving the space in the cavity and integrating more LD chips in the limited size of the cavity, thereby improving the maximum power of the laser output by the laser.

[0027] Optionally, the LD chip has two light-emitting end faces, the laser emitted from one of the end faces is referred to as forward laser, and the laser emitted from the other end face is referred to as backward laser. The end face of the optical fiber can be located on the light path of the forward laser, and the PD chip can be located on the light path of the backward laser.

[0028] The present application does not limit the relative positions of the two end faces on the LD chip. Optionally, the two end faces are located on two opposite planes on the LD chip, and the light paths of the corresponding forward laser and backward laser are located on the same straight line but in opposite directions. For example, the LD chip can be a fabry-perot (FP) cavity LD chip. Alternatively, due to the bending of the waveguide structure, the light paths of the forward laser and the backward laser can not be on the same straight line.

[0029] In a second aspect, the present application provides a pump laser, comprising a housing with a cavity inside, a packaging substrate, a plurality of laser diode chips and a plurality of optical fibers, the housing having an electrical connector and a fiber tail pipe, the packaging substrate and the plurality of laser diode chips being assembled in the cavity, the plurality of optical fibers respectively extending from the outside of the housing to the inside of the cavity via the fiber tail pipe; the plurality of LD chips are electrically connected to the electrical connector, respectively, the plurality of LD chips are used to respectively receive driving signals from the electrical connector and emit a plurality of laser beams under the driving of the driving signals; the end faces of the plurality of optical fibers are respectively located on the light paths of the plurality of laser beams, and the plurality of optical fibers are used to transmit the plurality of laser beams to the outside of the housing; the packaging substrate has a plurality of photodiode (PD) chips integrated thereon, the plurality of PD chips are electrically connected to the electrical connector through the packaging substrate, and the plurality of PD chips are used to convert a plurality of optical signals received from the plurality of LD chips into a plurality of electrical signals and output the plurality of electrical signals to the electrical connector.

[0030] In the pump laser's tube cavity, a package substrate integrated with multiple PD chips (referred to as multi-core substrate) is installed. Compared with installing multiple package substrates integrated with single PD chips (referred to as single-core substrate) respectively, it not only helps to reduce the packaging steps, reduce the assembly accuracy requirements of the package substrate, improve the packaging yield, and reduce the packaging cost, but also helps to save space in the cavity to integrate more LD chips in the limited size of the cavity, and improve the maximum power of the laser output by the laser. In addition, the multi-core substrate has a larger area than the single-core substrate, which not only helps to dissipate heat from the chips, but also the larger area of the package substrate helps to reduce the stress on the PD chips during subsequent packaging, improving the reliability of the PD chips.

[0031] Optionally, the multi-core substrate has multiple pads (referred to as PD pads), the multiple PD chips are connected to the multiple PD pads through an electrical interconnection structure in the multi-core substrate, and the multiple PD pads are directly connected to the electrical connector. In this way, it helps to avoid the multi-core substrate being electrically connected to the electrical connector through other substrates, thereby helping to reduce the number of substrates in the cavity to reduce costs and reduce the size of the tube.

[0032] Optionally, the multiple PD pads are all located in the area between the multiple PD chips and the electrical connector of the tube. Compared with assembling all or part of the multiple PD pads in the area between different PD chips, it helps to shorten the length of the electrical connection line between the PD pads and the electrical connector, reduce electrical loss and wiring complexity.

[0033] Optionally, at least two PD chips are connected in parallel to the same PD pad, which helps to reduce the number of PD pads on the PD substrate, reduce the number of electrical connection lines between the PD pads and the electrical connector, and reduce wiring complexity.

[0034] Optionally, the LD chip has two light-emitting end faces, the laser emitted from one of the end faces is referred to as forward laser, and the laser emitted from the other end face is referred to as backward laser. The end face of the optical fiber can be located on the light path of the forward laser, and the PD chip can be located on the light path of the backward laser.

[0035] The present application does not limit the relative position of the two end faces on the LD chip. Optionally, the two end faces are located on two opposite planes on the LD chip, and the light paths of the corresponding forward laser and backward laser are located on the same straight line but in opposite directions. For example, the LD chip can be an FP cavity LD chip. Alternatively, due to the bending of the waveguide structure, the light paths of the forward laser and the backward laser can not be on the same straight line.

[0036] The application does not limit the assembly manner of the plurality of LD chips and the plurality of optical fibers in the cavity. Optionally, the assembly manner of the plurality of LD chips and the plurality of optical fibers in the cavity can be understood with reference to the related solutions provided in the first aspect.

[0037] For example, optionally, the plurality of LD chips are integrated on the same packaging substrate, and the packaging substrate for integrating the plurality of LD chips (referred to as a multi-core substrate-LD) and the packaging substrate for integrating the plurality of PD chips (referred to as a multi-core substrate-PD) can be the same or different packaging substrates.

[0038] Optionally, the multi-core substrate-LD has a plurality of pads (referred to as LD pads), the plurality of LD chips are connected to the plurality of LD pads through the electrical interconnection structure in the multi-core substrate-LD, and the plurality of LD pads are directly connected to the electrical connector. In this way, it is beneficial to avoid that the multi-core substrate-LD is electrically connected to the electrical connector through other substrates, thereby facilitating to reduce the number of substrates in the cavity, to reduce the cost, and to reduce the size of the package.

[0039] Optionally, the plurality of LD pads are located in the region between the plurality of LD chips and the electrical connector of the package. Compared with assembling all or part of the plurality of LD pads in the region between different LD chips, it is beneficial to shorten the length of the electrical connection line between the LD pads and the electrical connector, to reduce the electrical loss and the wiring complexity.

[0040] Optionally, the plurality of optical fibers are fixed on the multi-core substrate-LD. For the convenience of description, the region on the multi-core substrate-LD for fixing the optical fibers is referred to as an optical fiber fixing region. Compared with fixing the plurality of optical fibers on other substrates, it is beneficial to reduce the number of substrates in the cavity, to reduce the cost, and to reduce the size of the package.

[0041] Optionally, the optical fiber fixing region has a plurality of limiting mechanisms, the plurality of limiting mechanisms are used for fixing the plurality of optical fibers, and the end faces of the plurality of optical fibers after being fixed are located on the light paths of the laser beams emitted by the plurality of LD chips. After the plurality of LD chips are integrated on the multi-core substrate, the positions of the light paths of the laser beams emitted by each of the plurality of LD chips relative to the multi-core substrate-LD are fixed. The plurality of limiting mechanisms can be prepared according to the positions of the plurality of light paths on the multi-core substrate-LD, so that the end faces of the plurality of optical fibers fixed on the plurality of limiting mechanisms are located on the plurality of light paths. In this way, as long as the plurality of optical fibers are installed on the plurality of limiting mechanisms, the coupling between the LD chips and the optical fibers can be realized, thereby facilitating to reduce the difficulty of active coupling, and even facilitating to avoid searching for the installation positions of the optical fibers in the optical fiber fixing region through the active coupling, thereby facilitating to reduce the assembly difficulty and the assembly cost.

[0042] Optionally, a plurality of grooves are processed on the multi-core substrate to form a plurality of limiting mechanisms, and the plurality of optical fibers are respectively installed in the plurality of grooves, which is conducive to the stable fixing of the optical fibers on the multi-core substrate and improves the reliability of the laser. Since the optical fibers are fixed in the grooves, the coupling between the end faces of the optical fibers fixed in the grooves and the LD chips can be facilitated by processing a plurality of grooves in the projection area of the multi-core substrate, which improves the coupling efficiency of the optical signals between the LD chips and the optical fibers, reduces the difficulty of finding the processing position of the limiting mechanism in the optical fiber fixing area, and improves the implementability of the scheme.

[0043] The application does not limit the shape of the groove. For example, the groove can be a V-shaped groove, a square groove, a trapezoidal groove, or a semicircular groove, etc.

[0044] The application does not limit the depth of the groove. After the optical fiber is installed in the groove, all or part of the optical fiber is located in the groove.

[0045] The application does not limit the fixed position of the optical fiber in the groove. For example, the optical fiber can be fixed on one or more surfaces in the groove.

[0046] The application does not limit the fixing mode between the optical fiber and the groove. For example, the optical fiber can be fixed on the surface of the groove by welding or pasting, etc.

[0047] Optionally, based on the fact that the plurality of optical fibers are respectively bonded on the multi-core substrate by the adhesive, the multi-core substrate has a groove between the area for bonding the plurality of optical fibers and the plurality of LD chips, which is conducive to preventing the adhesive from spreading to the chip end face during the process of bonding the optical fiber on the multi-core substrate, thereby avoiding the overflow of the adhesive to the optical path or the LD chip, affecting the transmission of the optical signal, and even causing the adhesive to overheat and damage the device.

[0048] The application does not limit the type of adhesive. For example, the adhesive can be glue or solder, etc.

[0049] Optionally, the application proposes that, in order to improve the reliability of the laser, a temperature detection element can be integrated in the cavity to detect the temperature in the cavity, which is conducive to keeping the temperature in the cavity within the working temperature range of the LD chip and improving the reliability of the LD chip. In addition, the temperature detection element can be integrated on the multi-core substrate, and the multi-core substrate is connected to the electrical connector, which is conducive to reducing the number of substrates in the cavity to reduce the cost and the size of the tube shell, compared with integrating the temperature detection element on other substrates.

[0050] In the solutions of the first aspect and the second aspect, the electrical signal output by the PD chip can be used to determine the parameter of the laser beam emitted by the LD chip, and can be used to adjust the driving signal input to the LD chip to stabilize the parameter of the laser beam emitted by the LD chip. The parameter of the laser beam can include wavelength and / or power.

[0051] In a third aspect, the present application provides an optical amplification module, which comprises one or more gain optical fibers and a pump laser as described in the first aspect or any possible implementation manner of the first aspect or the second aspect or any possible implementation manner of the second aspect; the pump laser is configured to input a laser beam to the one or more gain optical fibers; and the one or more gain optical fibers are configured to transmit an optical signal received by the optical amplification module and amplify the power of the optical signal under the excitation of the laser beam.

[0052] In a fourth aspect, the present application provides an optical amplification system, which comprises a sending module and an optical amplification module as described in the third aspect; the sending module is configured to send an optical signal to the optical amplification module; and the optical amplification module is configured to receive the optical signal, amplify the power of the optical signal, and output the amplified optical signal. BRIEF DESCRIPTION OF DRAWINGS

[0053] FIG. 1 schematically shows a possible structure of an optical amplification module;

[0054] FIG. 2 schematically shows a structure of a pump laser comprising three LD chips;

[0055] FIG. 3 schematically shows a structure of a pump laser comprising four LD chips;

[0056] FIG. 4 schematically shows a possible structure of a pump laser using a multi-chip substrate package provided by the present application;

[0057] FIGS. 5-1 to 5-3 schematically show possible structures of a multi-chip substrate-LD, respectively;

[0058] FIGS. 6-1 to 6-4 schematically show possible structures of a fiber fixing area;

[0059] FIGS. 7-1 to 7-4 schematically show possible structures of a multi-chip substrate-PD, respectively;

[0060] FIG. 8 schematically shows a possible structure of a pump laser using a two-in-one substrate package;

[0061] FIG. 9 schematically shows a possible structure of a pump laser using a three-in-one substrate package;

[0062] FIG. 10 schematically shows a possible structure of a pump laser using a four-in-one substrate package;

[0063] Fig. 11 schematically shows a possible structure of a pump laser using a multi-core substrate-PD assembly;

[0064] Fig. 12 schematically shows a possible structure of a pump laser in which multiple PD chips and multiple optical fibers are respectively integrated. DETAILED DESCRIPTION

[0065] The present application provides an optical amplification module (or optical amplifier) for amplifying power of an input optical signal. The present application does not limit the application scenario of the optical amplification module. The optical amplification module can be applied in the field of optical communication, for example, the optical amplification module can amplify an optical signal carrying data, and the optical amplification module can be deployed at a data sending end and / or a data receiving end and / or an optical link. With the development and application of wavelength division multiplexing (WDM) technology, the communication capacity has been greatly improved. The optical amplification module can also be applied in the industrial field, for example, to amplify the laser emitted by the laser source in the laser radar.

[0066] Fig. 1 schematically shows a possible structure of an optical amplification module. As shown in Fig. 1, the optical amplification module includes a controller, a pump laser, and one or more doped gain fiber segments.

[0067] The controller can include a temperature management unit and an LD driving unit. The LD driving unit is used to control the pump laser to emit laser, and the temperature management unit is used to control the temperature of the pump laser. The functions of the temperature management unit and the LD driving unit will be introduced later in conjunction with examples, which will not be expanded here. The controller can include more or fewer units, for example, the controller can not include the temperature management unit.

[0068] The pump laser is electrically connected to the controller through an electrical connector. In Fig. 1, the electrical connection between the pump laser and the controller is represented by a solid connection line. The pump laser can emit laser under the control of the controller. In Fig. 1, the optical link (such as an optical fiber) is represented by a dashed connection line.

[0069] The optical amplification module includes optical fibers, and all or part of the optical fibers are gain fibers. In Fig. 1, the gain fibers are represented by thick dashed connection lines. In actual applications, the optical amplification module can include more gain fiber segments. The present application does not limit the type of elements doped in the gain fiber segments, for example, the gain fiber segments can be doped with at least one of erbium, ytterbium, and thulium. Hereinafter, the optical amplification module is taken as an erbium-doped fiber amplifier (EDFA) as an example.

[0070] The optical signal can be input into the optical fiber of the optical amplifier module via the input end of the optical amplifier module. The optical signal transmitted by the optical fiber and the laser emitted by the pump laser (or excitation light) can be combined into the gain fiber segment via the multiplexer. The laser can excite the erbium in the gain fiber segment to undergo energy level transition, achieve population inversion, and thus increase the power or signal strength of the optical signal in the gain fiber segment. The number of pump lasers in the optical amplifier module is not limited in the present application, and in actual applications, the optical amplifier module can include a larger number of pump lasers.

[0071] The present application does not limit the combination method of the optical signal and the excitation light, and FIG. 1 takes the combination of the two through the multiplexer into the gain fiber segment as an example. FIG. 1 is only a structural example of the optical amplifier module, and in actual applications, the optical amplifier module can include more or fewer components. For example, the optical amplifier module can not include a controller, and the pump laser can be connected to the controller outside the optical amplifier module through an electrical connector.

[0072] As the array size of the laser radar continues to increase, the communication capacity continues to increase, and the power of the optical signal input into the optical amplifier module continues to increase. As the wavelength range of the EDFA application is widened and the number of wavelengths increases (from the C band to the L band), and considering the requirements of miniaturization and low cost of the optical amplifier module, the power requirement of the laser output by the pump laser continues to increase, for example, from 0.5W, 1W to 2W-3W. Laser diode (LD) is a key component of the pump laser.

[0073] However, due to the limitation of the light emitting efficiency of the LD material itself, the light emitting capacity of a single LD chip is limited. As the power demand of the EDFA increases, the power carried by a single LD chip in the pump laser continues to increase, which gradually cannot meet the demand of the EDFA, and in addition, as the power carried by a single LD chip increases, the reliability of the device becomes worse (the failure rate of the PUMP device increases exponentially with the output power). In order to meet the demand of high light emitting power, more LD chips need to be integrated in the same pump laser, which greatly increases the assembly cost of the pump laser.

[0074] FIG. 2 schematically shows the structure of the pump laser. As shown in FIG. 2, the pump laser includes a heat sink substrate, a thermistor mounted on the heat sink substrate, and three laser elements, each of which can include an LD package substrate, a PD package substrate, and a fiber base for fixing an optical fiber. The elements with the same serial number in FIG. 2 are the same laser element, for example, the PD package substrate 1 on which the PD chip 1 is mounted, the LD package substrate 1 on which the LD chip 1 is mounted, and the fiber base 1 are the same laser element.

[0075] The pump laser further generally includes a housing having a cavity inside. The components shown in FIG. 2 are assembled in the cavity. The housing further has an electrical connector. The thermistor, the LD package substrate, and the PD package substrate are electrically connected to the electrical connector, respectively. The housing further has a fiber tail pipe. Three optical fibers can extend from outside of the housing to inside of the cavity through the fiber tail pipe and are fixed on the three fiber pedestals shown in FIG. 2, respectively. The housing and the fiber tail pipe have through holes, respectively, through which the optical fibers can extend from outside of the housing to the cavity.

[0076] The package substrate is a carrier of the semiconductor chip. During the production of the integrated circuit chip, the chip needs to be placed on a carrier with good heat conduction performance, protection performance, and good mechanical strength. This carrier is the package substrate, which is usually made of metal or ceramic materials. The package substrate is usually composed of an electronic circuit carrier (such as a substrate material) and an electrical interconnection structure (such as an electronic circuit, a via hole, etc.). The package substrate usually has a pad pattern layout for providing the chip with an electrical signal transmission path. The present application does not limit the pattern of the pads and the pattern of the electrical interconnection structure on the package substrate.

[0077] The LD package substrate refers to the package substrate in which the LD chip is packaged. The LD chip is used to receive a driving signal from the controller through the electrical connector and emit laser under the driving of the driving signal. The LD chip has two light-emitting end faces. The LD chip emits forward laser through one light-emitting end face and emits backward laser through the other light-emitting end face. The present application does not limit the type of the driving signal. The driving signal can be a current signal or a voltage signal.

[0078] The PD package substrate refers to the package substrate in which the PD chip is packaged. The end face of the PD chip for detecting the optical signal (referred to as the PD light-sensitive surface or the PD light-sensitive surface) is located on the optical path of the backward laser. The PD chip is used to detect the parameters of the backward laser and send an electrical signal indicating the detection result to the controller through the electrical connector. Optionally, the controller can adjust the driving signal sent to the LD chip according to the received electrical signal to control the parameters of the laser emitted by the LD chip. The parameters of the laser can include but are not limited to the power and / or wavelength of the laser.

[0079] The optical fiber is fixed on the fiber pedestal so that the end face of the optical fiber is located on the optical path of the forward laser. The optical fiber is used to receive or couple the forward laser from the end face of the optical fiber and transmit the forward laser to the outside of the housing and access to the upper application system (such as the gain optical fiber of the optical amplification module). Optionally, a fiber bragg grating (FBG) can be engraved at a position a distance away from the end face of the optical fiber to stabilize the wavelength of the laser output by the laser. The fiber pedestal not only provides support for the fixation of the optical fiber, but also compensates for the height difference between the port of the LD chip and the heat sink substrate.

[0080] The thermistor is used to detect the temperature of the heat sink substrate and outputs the detection result to the controller through the electrical connector.

[0081] In order to meet the demand of high light emitting power, more LD chips need to be integrated in the same pump laser. Fig. 3 schematically shows the structure of a pump laser integrating 4 LD chips. The elements shown in Fig. 3 can be understood with reference to the corresponding elements shown in Fig. 2, and the difference between them is that, compared with the pump laser shown in Fig. 2, the pump laser shown in Fig. 3 adds one laser element, i.e. adds the fourth laser element, which specifically includes the LD packaging substrate 4, the PD packaging substrate 4 and the optical fiber base 4. In order to make the drawing simple, Fig. 3 does not show the labels of the elements other than the newly added element (i.e. the fourth laser element), and the labels and introduction of the other elements can be understood with reference to the related contents of Fig. 2, which will not be described here.

[0082] With the increase of the number of LD packaging substrates in the pump laser, the number of components that need to be packaged on a single heat sink substrate is multiplied, as shown in Fig. 3, the newly added one laser element needs to be additionally packaged with 3 substrates, which leads to complex packaging process, reduced overall reliability and yield of device level, and damage of a single element in the packaging process will cause the entire laser to be scrapped. More elements not only involve more assembly times and larger layout space, but also greatly increase the complexity of packaging, increase the packaging cost, and are difficult to meet the requirements of small size and low cost of optical amplification modules.

[0083] The present application proposes that, in the pump laser shell cavity, a packaging substrate integrated with multiple chips (referred to as multi-chip substrate) is installed. Compared with installing multiple packaging substrates integrated with a single chip (referred to as single-chip substrate) respectively, it is not only conducive to reducing the packaging steps, reducing the complexity of the packaging system, improving the packaging reliability and yield. Moreover, since the size of the chip is generally much smaller than the size of the single-chip substrate, integrating multiple chips on the same packaging substrate is conducive to improving the integration degree, integrating more chips in the limited size of the cavity, improving the maximum power of the laser output by the laser (the overall power is generally proportional to the number of LD chips), adapting to higher performance of EDFA (such as higher optical power amplification capability), and also conducive to reducing the load of a single LD chip and improving the reliability of the LD chip (the chip failure rate generally increases exponentially with the increase of the chip power). In addition, the multi-chip substrate has a larger area than the single-chip substrate, which is not only conducive to heat dissipation of the chip, but also the larger area of the packaging substrate is conducive to reducing the stress on the chip in subsequent packaging and improving the reliability of the chip.

[0084] Next, based on the above concept, the scheme provided by the present application is introduced.

[0085] In a possible implementation, the multi-chip substrate-LD integrated with multiple LD chips and the multi-chip substrate-PD integrated with multiple PD chips are respectively arranged in the tube cavity of the pump laser.

[0086] FIG. 4 schematically shows a possible structure of the pump laser provided in the present application. As shown in FIG. 4, the pump laser includes a shell with a cavity inside, a refrigerator, a heat sink substrate, a multi-chip substrate-LD, a multi-chip substrate-PD, a multi-fiber base, multiple optical fibers (or optical guide fibers), an electrical connector, and optical fiber tail pipes.

[0087] As shown in FIG. 4, the shell or tube can be a cavity that provides a fixing space for internal elements. The shell can include a bottom plate and a cover plate (not shown) matched with the bottom plate. After the internal elements are arranged on the bottom plate, the cover plate is sealed to form a sealed cavity, so as to protect the working state of the components in the tube stable.

[0088] As shown in FIG. 4, the electrical connector is arranged on the shell, and the electrical connector includes multiple pins, each of which is used to transmit an electrical signal in the cavity to the outside of the shell. FIG. 4 takes an example in which the multiple pins in the electrical connector are located on two side surfaces of the shell. The present application does not limit the position of the electrical connector on the shell. Alternatively, all the pins in the electrical connector can be located on the same side surface of the shell.

[0089] As shown in FIG. 4, the pump laser includes three optical fiber tail pipes on the shell. Three optical fibers respectively extend from the outside of the shell into the cavity through the three optical fiber tail pipes and are fixed on the same multi-fiber base. The present application does not limit the number of optical fiber tail pipes in the pump laser. In some examples, multiple optical fibers can extend from the outside of the shell into the cavity through the same optical fiber tail pipe. Correspondingly, the number of optical fiber tail pipes can be less than the number of optical fibers extending into the cavity.

[0090] As shown in FIG. 4, the thermistor, the multi-chip substrate-LD, the multi-chip substrate-PD, and the optical fiber substrate are respectively arranged on the heat sink substrate, and the heat sink substrate is arranged on the refrigerator. The refrigerator is used to reduce the temperature of the environment, thereby facilitating the reduction of the temperature of the heat sink substrate. The present application does not limit the specific implementation of the refrigerator. For example, the refrigerator can be a thermo electric cooler (TEC). The heat sink substrate is a substrate prepared by using a heat-conductive material, which can transmit the heat generated by the elements (for example, the multi-chip substrate-LD) carried thereby to the refrigerator. The present application does not limit the type of heat-conductive material. For example, a substrate containing at least one high-thermal-conductivity material such as aluminum nitride (AlN), silicon carbide (SiC), red copper, tungsten copper, and ceramic can be selected as the heat sink substrate shown in FIG. 4. In order to improve the reliability of the multi-chip substrate-LD, a heat sink substrate with a thermal expansion coefficient close to that of the multi-chip substrate can be arranged in the cavity.

[0091] The thermistor is used to detect the temperature of the heat sink substrate. Since the multi-core substrate-LD is mounted on the heat sink substrate, and the package substrate and the heat sink substrate generally have good heat conduction performance, it is beneficial to detect the temperature of the LD chip through the thermistor. For example, the thermistor can monitor the temperature of the die (or in the cavity). When the temperature deviates from the target temperature, the temperature drift of the die is suppressed by adjusting the input current / voltage of the refrigerator through the peripheral module (such as the temperature management unit), thereby ensuring that the die temperature is stable within the working temperature range of the chip. That is, the thermistor and the refrigerator can form a feedback loop to maintain the die temperature within the working temperature range of the LD chip to ensure the performance of the LD chip.

[0092] The heat sink substrate can provide a pattern of electrical signal paths for the at least one electrical component carried thereby. For example, the thermistor can be connected to the electrical connector through the electrical interconnection structure in the heat sink substrate.

[0093] Optionally, the thermistor and the refrigerator are respectively connected to the temperature management unit in the controller through the electrical connector. The thermistor is used to send the detection result of the temperature to the temperature management unit, and the temperature management unit is used to control the temperature of the refrigerator according to the received detection result, thereby facilitating the temperature of the LD chip to be maintained within the working temperature range of the LD chip, thereby ensuring the performance of the LD chip.

[0094] The thermistor is a component for detecting temperature (referred to as a temperature detection component). In actual applications, the thermistor can be replaced by other types of temperature detection components as needed.

[0095] As shown in FIG. 4, three LD chips are packaged on the multi-core substrate-LD. The three LD chips can be respectively electrically connected to the electrical connector (not specifically shown in FIG. 4) through the multi-core substrate-LD. The LD chip has two light emitting end faces. In this application, the light emitting end face facing the optical fiber is referred to as the forward end face, and the light emitting end face facing the PD chip is referred to as the backward end face.

[0096] The LD chip is used to receive a driving signal from the LD driving unit in the controller through the electrical connector, and emit laser light through the two light emitting end faces under the driving of the driving signal. For ease of description, the laser light emitted by the LD chip through the forward end face is referred to as forward laser light, and the laser light emitted through the backward end face is referred to as backward laser light. The power of the forward laser light is generally greater than the power of the backward laser light.

[0097] Figure 5-1 schematically shows a possible structure of the multi-chip-substrate-LD. As shown in Figure 5-1, three LD chips are integrated on the multi-chip-substrate-LD, and both the multi-chip-substrate-LD and the LD chips are cuboid structures. The front end face and the back end face of the LD chips can be located on two bottom faces (i.e. the planes perpendicular to the x direction in Figure 5) of the cuboid structures, respectively. The x direction shown in Figure 5-1 can represent the extending direction of the optical fiber in the cavity, and with reference to Figure 4, the surface of the housing with the electrical connector is parallel to the x direction. In order to improve the utilization of the layout space in the cavity, the surface of the multi-chip-substrate-LD facing the electrical connector can be parallel to the x direction, while the surface facing the end face of the optical fiber can be perpendicular to the x direction. As shown in Figure 5-1, the heights of the three LD chips are parallel to the x direction, or in other words, the light paths of the forward laser and the back laser emitted by the LD chips are parallel to the x direction. When the end face of the optical fiber is perpendicular to the extending direction of the optical fiber, it is easy to cause the forward laser emitted by the LD chips to be perpendicular to the end face of the optical fiber, thereby increasing the reflectivity of the end face of the optical fiber to the forward laser and reducing the coupling efficiency of the optical fiber to the forward laser.

[0098] Figure 5-2 schematically shows another possible structure of the multi-chip-substrate-LD. The difference between Figure 5-2 and Figure 5-1 is that the heights of the three LD chips are no longer parallel to the x direction. Taking the case that the two bottom faces of the multi-chip-substrate-LD are perpendicular to the x direction, the angle a between the height of the LD chip 3 and the bottom face is not 90 degrees. In other words, the light paths of the forward laser and the back laser emitted by the LD chips are not parallel to the x direction. In this way, even if the end face of the optical fiber is perpendicular to the extending direction of the optical fiber, it is beneficial to avoid the forward laser emitted by the LD chips being perpendicular to the end face of the optical fiber, thereby reducing the reflectivity of the end face of the optical fiber to the forward laser, increasing the coupling efficiency of the optical fiber to the forward laser, and improving the power of the laser output by the pump laser.

[0099] Figure 5-3 schematically shows another possible structure of the multi-chip-substrate-LD. The difference between Figure 5-3 and Figure 5-1 or Figure 5-2 is that the height (or the length along the x direction) of the plurality of LD chips is smaller than the length of the multi-chip-substrate-LD along the x direction. In this way, it is beneficial to increase the area of the multi-chip-substrate-LD, which not only helps to optimize the stress buffering capability of the multi-chip-substrate-LD, reduce the stress generated by subsequent packaging on the LD chips, and improve the reliability of the LD chips, but also helps to reduce the difficulty of laying out the electrical interconnection structure in the multi-chip-substrate-LD, reduce the cost of the multi-chip-substrate-LD, and further reduce the cost of the pump laser.

[0100] The present application does not limit the packaging method of the LD chips on the multi-chip-substrate-LD. In order to optimize the heat dissipation of the LD chips, the LD chips can be packaged in a flip-chip (or flip-chip) form.

[0101] In order to reduce the back loss of the forward laser at the end face of the optical fiber, the end face of the optical fiber can be coated with an anti-reflection film, and / or the end face of the optical fiber can be coupled with a lens or processed (for example, by grinding) to form a lens.

[0102] Optionally, the multi-core substrate-LD can have a plurality of pads (referred to as LD pads), the plurality of LD chips are connected to the plurality of LD pads through the electrical interconnection structure in the multi-core substrate-LD, and the plurality of LD pads are directly connected to the electrical connector. In this way, it is beneficial to avoid that the multi-core substrate-LD is electrically connected to the electrical connector through other substrates (such as a heat sink substrate), thereby avoiding the processing of the electrical interconnection structure in the heat sink substrate, reducing the cost of the heat sink substrate, and shortening the length of the connection line between the LD chip and the electrical connector, thereby reducing the electrical loss and the wiring complexity.

[0103] Optionally, the plurality of LD pads are located in the area between the plurality of LD chips and the electrical connector of the package (for example, the area in the dashed box on the multi-core substrate-LD shown in FIG. 5-1). Compared with assembling all or part of the plurality of LD pads in the area between different LD chips, it is beneficial to shorten the length of the electrical connection line between the LD pad and the electrical connector, thereby reducing the electrical loss and the wiring complexity.

[0104] Continuing to refer to FIG. 4, the three optical fibers are fixed on the multi-fiber base, respectively, and the end faces of the three optical fibers are located on the light paths of the forward lasers emitted by the three LD chips, respectively, and the optical fibers are used to transmit the incident laser to the outside of the housing.

[0105] FIG. 6-1 schematically shows the structure of the multi-fiber base. As shown in FIG. 6-1, the multi-fiber base is a flat plate type optical fiber fixing base (or a flat plate type optical fiber fixing support), that is, the multi-fiber base is a cuboid, and one surface of the multi-fiber base is used to fix the three optical fibers, and this surface is referred to as an optical fiber fixing surface or an optical fiber fixing area. After the multi-core substrate-LD and the multi-fiber base are fixed on the heat sink substrate, respectively, the fixing positions of each of the three optical fibers in the optical fiber fixing area shown in FIG. 6-1 can be found by means of active coupling, and then the three optical fibers are fixed on the found fixing positions, respectively, thereby ensuring the coupling efficiency of the optical fibers to the forward laser. Then, the optical fiber tail pipe can be sealed, and the cover plate can be sealed to the bottom plate by welding.

[0106] Optionally, the optical fiber fixing area has three grooves to form three limiting mechanisms, and the three optical fibers are installed in the three grooves, respectively, which is beneficial to more stably fix the optical fibers on the multi-core substrate and improve the reliability of the laser.

[0107] The application does not limit the shape of the groove. FIGS. 6-2 to 6-4 schematically show other possible structures of the multi-fiber base. As shown in FIG. 6-2, the fiber fixing region of the multi-fiber base can have three V-shaped grooves (referred to as V-shaped grooves) for fixing one optical fiber on each V-shaped groove. As shown in FIGS. 6-3 and 6-4, the fiber fixing region of the multi-fiber base can have three square grooves for fixing one optical fiber in each square groove.

[0108] The application does not limit the fixing position of the optical fiber in the groove. For example, the optical fiber can be fixed on one or more surfaces in the groove. As shown in FIG. 6-2, the optical fiber can be fixed on two surfaces of the V-shaped groove. The width of the square groove shown in FIG. 6-3 can be equal to or slightly greater than the diameter of the optical fiber, and the optical fiber can be fixed on two opposite surfaces in the square groove or fixed on three surfaces in the square groove. Compared with the groove shown in FIG. 6-2, the width of the groove shown in FIG. 6-3 can be greater, and the optical fiber can be fixed on one side (for example, the side filled with diagonal lines in the figure) of the groove shown in FIG. 6-3. Therefore, at least one groove of the multi-fiber base can be an L-shaped groove as shown in FIG. 6-3.

[0109] FIGS. 6-2 to 6-4 are only examples, and the groove can also be processed into other shapes, such as trapezoidal groove or semicircular groove, etc.

[0110] The application does not limit the depth of the groove. After the optical fiber is installed in the groove, all or part of the optical fiber is located in the groove. The application does not limit the fixing method between the optical fiber and the groove. For example, the optical fiber can be fixed on the surface of the groove by welding or sticking (or bonding). The application does not limit the type of adhesive used to bond the optical fiber. For example, the adhesive can be glue or solder, etc.

[0111] In some examples, the groove in the fiber fixing region introduced in the foregoing can also be replaced by other types of optical fiber fixing mechanisms, as long as the optical fiber can be fixed in the optical fiber fixing mechanism, and it is beneficial to improve the stability of the optical fiber in the fiber fixing region, and the end face of the fixed optical fiber is located in the light path of the forward laser.

[0112] Continuing to refer to FIG. 4, the multi-core substrate-PD is packaged with 3 PD chips, and the 3 PD chips can be electrically connected to the electrical connector (not shown in FIG. 4) through the multi-core substrate-PD, respectively. The PD light-sensitive surfaces on the PD chips are respectively corresponding to the light paths of the backscattered laser emitted by the LD chips, and the PD chips are used to detect the parameters (such as power and / or wavelength) of the backscattered laser, and send the electrical signals carrying the detection results to the LD driving unit through the electrical connector. Since the parameters of the backscattered laser can generally be used to determine the parameters of the forward laser, it is beneficial for the LD driving unit to send the driving signals to the LD chips according to the parameters of the backscattered laser, so as to stabilize the parameters of the forward laser emitted by the LD chips. The controller can also detect the working state of the LD chips according to the parameters (such as signal strength) of the backscattered laser. For example, when the signal strength of the backscattered laser is lower than a threshold, the controller can determine that the corresponding LD chip (i.e. the same LD chip) is failed or malfunctioning.

[0113] Compared with installing the multi-core substrate-PD in the cavity and installing a plurality of packaging substrates integrated with a single PD chip in the cavity, respectively, not only is it beneficial to reduce the packaging steps, reduce the complexity of the overall packaging of the device, improve the fault tolerance rate of the device packaging process (or reduce the requirement for the assembly accuracy of the packaging substrate), improve the packaging yield, and reduce the packaging cost, but also, since the size of the chip is generally much smaller than the size of the single-core substrate, it is beneficial to save space in the cavity, thereby facilitating the integration of more LD chips in a limited size cavity, and improving the maximum power of the laser output by the laser. In addition, the packaging substrate integrated with multiple PD chips has a larger area than the packaging substrate integrated with a single PD chip, which is not only beneficial to heat dissipation of the PD chip, but also the larger area of the packaging substrate is beneficial to reduce the stress on the PD chip in subsequent packaging, thereby improving the reliability of the PD chip. Moreover, the assembly of the multi-core substrate-PD and the multi-core substrate-LD can be packaged in parallel, thereby facilitating the shortening of the packaging period of a single device and reducing the cost.

[0114] Optionally, the PD substrate has a plurality of pads (referred to as PD pads), and the plurality of PD chips can be connected to the plurality of PD pads through the electrical interconnection structure in the PD substrate, and the plurality of PD pads are directly connected to the electrical connector. In this way, it is beneficial to avoid the PD substrate being electrically connected to the electrical connector through other substrates, thereby facilitating the reduction in the number of substrates in the cavity to reduce the cost and reduce the size of the tube shell.

[0115] Optionally, at least two PD chips are connected in parallel to the same PD pad, which is beneficial to reduce the number of PD pads on the PD substrate, reduce the number of electrical connection lines between the PD pads and the electrical connector, and reduce the wiring complexity.

[0116] Fig. 7-1 to Fig. 7-4 respectively show possible structures of the multi-chip substrate-PD. As shown in Fig. 7-1 to Fig. 7-4, the three PD chips and the multi-chip substrate-PD are cuboid, and the multi-chip substrate-PD has a positive electrode pad and a negative electrode pad. The positive electrode pad is a continuous pad area on the substrate (referred to as the positive electrode pad), and the negative electrode pad is a continuous pad area on the substrate (referred to as the negative electrode pad). The positive electrodes of the plurality of PD chips are electrically connected to the same positive electrode pad, and the negative electrodes of the plurality of PD chips are electrically connected to the same negative electrode pad. The positive electrode pad and the negative electrode pad are respectively electrically connected to the electrical connector. Compared with connecting the plurality of PD chips to different pads of the multi-chip substrate-PD, the number of leads (or electrical connecting wires) between the multi-chip substrate-PD and the electrical connector is reduced, thereby reducing the number of leads, reducing the complexity of the packaging process, shortening the distance of electrical signal transmission, reducing the adverse effects of resistance, inductance, etc., improving the electrical performance of the PD chip, and since the PD chip directly contacts the packaging substrate-PD, the PD chip can be better cooled, and the stability and reliability of the PD chip are improved.

[0117] The present application does not limit the positional relationship between the surface of the PD chip (referred to as the packaging surface) for fixing on the multi-chip substrate-PD and the photosensitive surface on the PD chip. As shown in Fig. 7-1 and Fig. 7-2, the packaging surface and the photosensitive surface are two opposite surfaces, or in other words, the packaging surface and the photosensitive surface are parallel to each other. The three PD chips can be respectively fixed on the surface of the multi-chip substrate-PD facing the LD chip.

[0118] Alternatively, as shown in Fig. 7-3 and Fig. 7-4, the packaging surface and the photosensitive surface are two adjacent or perpendicular surfaces. The three PD chips can be respectively fixed on the surface of the multi-chip substrate-PD parallel to the light path of the laser away from the laser.

[0119] The present application does not limit the relative position between the positive electrode and the negative electrode of the PD chip. The negative electrode and the positive electrode of the PD chip can be located on different surfaces of the PD chip, as shown in Fig. 7-1 and Fig. 7-3, the surfaces where the negative electrode and the positive electrode are located are parallel to each other. The negative electrode of the PD chip can be located on the packaging surface of the PD chip, and the electrical connection between the negative electrode of the PD chip and the negative electrode pad can be realized by welding the packaging surface of the PD chip on the negative electrode pad, thereby reducing the number of leads, shortening the distance of electrical signal transmission, reducing the adverse effects of resistance, inductance, etc., improving the electrical performance of the PD chip, and since the PD chip directly contacts the packaging substrate-PD, the PD chip can be better cooled, and the stability and reliability of the PD chip are improved. The positive electrode of the PD chip can be electrically connected to the positive electrode pad through a lead.

[0120] Alternatively, the negative and positive poles of the PD chip can be located on the same surface of the PD chip. As shown in FIG. 7-2 and FIG. 7-4, the negative and positive poles of the PD chip can be located on a surface parallel to the surface of the package, and the negative and positive poles are electrically connected to the negative and positive pads, respectively, through different leads.

[0121] The application does not limit the material of the leads as long as the leads have good electrical conductivity. For example, the leads can be gold wires.

[0122] In the above, the same type of components are integrated on the same substrate as an example. In order to further reduce the number of substrates in the cavity, reduce the assembly times, and save the layout space in the cavity, at least two different types of components can be integrated on the same substrate.

[0123] In some examples, two different types of components can be integrated on the same substrate. For example, the multi-core substrate-LD and the multi-core substrate-PD introduced above are the same package substrate (referred to as a two-in-one substrate), and the plurality of PD chips and the plurality of LD chips are integrated on the same two-in-one substrate, or a plurality of optical fibers are fixed on the multi-core substrate-LD introduced above.

[0124] FIG. 8 schematically shows a possible structure of a packaged pump laser using a two-in-one substrate. For the sake of simplicity of the drawing, FIG. 8 only identifies the heat sink substrate, the refrigerator, the thermistor, and the third laser component (i.e., the PD chip 3, the LD chip 3, and the optical fiber base 3), and the annotations and descriptions of other components can be understood with reference to the related content of FIG. 4, which will not be described herein again. The difference between the laser shown in FIG. 8 and the laser shown in FIG. 4 is that in the laser shown in FIG. 8, the three PD chips and the three LD chips are integrated on the same package substrate (i.e., the two-in-one substrate), and in the assembly process, the multi-core substrate-LD and the multi-core substrate-PD do not need to be installed on the heat sink substrate respectively, but the two-in-one substrate can be installed on the heat sink substrate. In this way, not only is it beneficial to reduce the number of substrates and reduce costs, but it is also beneficial to reduce the packaging steps, reduce the requirement for assembly precision of the package substrate, improve the packaging yield, and reduce the packaging cost. In addition, the further improvement of the integration degree is also beneficial to save the space in the cavity, thereby being beneficial to integrate more LD chips in the limited size of the cavity and improve the maximum power of the laser output by the laser. Compared with the multi-core substrate-PD or the multi-core substrate-LD, the two-in-one substrate with more integrated chips will have a larger area, which is not only beneficial to heat dissipation of the chips, but also the larger area of the package substrate is beneficial to reduce the stress generated by subsequent packaging on the chips, thereby improving the reliability of the PD chips and the LD chips.

[0125] In practical applications, referring to FIG. 4, a plurality of optical fibers can be fixed on the same optical fiber base (i.e., a multi-fiber base) to reduce the number of substrates and the number of encapsulations, reduce the cost of the pump laser, and save the layout space in the cavity and reduce the volume of the pump laser.

[0126] In some examples, three different types of elements can be integrated on the same substrate. For example, the multi-core substrate-LD and the multi-core substrate-PD described above are the same encapsulation substrate, and a plurality of optical fibers are fixed on the encapsulation substrate, or the multi-core substrate-LD and the multi-core substrate-PD described above are the same encapsulation substrate, and a thermistor is assembled on the encapsulation substrate. In order to facilitate distinction, this encapsulation substrate is referred to as a three-in-one substrate. In this way, it is beneficial to reduce the number of substrates in the cavity, not only to reduce the number of assemblies and reduce the assembly cost, but also to further save space in the cavity and integrate more LD chips in a limited size cavity to increase the maximum power of the laser output by the laser.

[0127] FIG. 9 schematically shows a possible structure of a pump laser using a three-in-one substrate. In order to simplify the drawing, FIG. 9 only identifies the heat sink substrate, the refrigerator, the thermistor, and the third laser element (i.e., the PD chip 3 and the LD chip 3), and the annotations and descriptions of other elements can be understood with reference to the related content of FIG. 4, which will not be repeated here. The difference between the laser shown in FIG. 9 and the laser shown in FIG. 8 is that in the laser shown in FIG. 9, the three PD chips, the three LD chips, and the three optical fibers are all mounted on the same encapsulation substrate (i.e., the three-in-one substrate), and in the assembly process, instead of mounting the two-in-one substrate and the plurality of optical fiber bases on the heat sink substrate, the three-in-one substrate is mounted on the heat sink substrate. In this way, by reducing the number of substrates in the cavity, it is not only beneficial to reduce the number of assemblies and reduce the cost, but also beneficial to further save space in the cavity and integrate more LD chips in a limited size cavity to increase the maximum power of the laser output by the laser. Compared with the two-in-one substrate, the three-in-one substrate used to fix the optical fiber will have a larger area, which is not only beneficial to the heat dissipation of the chip, but also the larger area of the encapsulation substrate is beneficial to reduce the stress on the chip in subsequent encapsulation, and improve the reliability of the PD chip and the LD chip.

[0128] When the optical fiber and the LD chip are fixed on the same encapsulation substrate (such as the two-in-one substrate or the three-in-one substrate or the four-in-one substrate), the area of the encapsulation substrate used to fix the optical fiber can still be referred to as the optical fiber fixing area, and the optical fiber fixing area can be understood with reference to the related content described above. For example, the optical fiber fixing area can have a plurality of limiting mechanisms, such as grooves.

[0129] The position of the light path of the forward laser emitted by each of the three LD chips is fixed relative to the packaging substrate after the three LD chips are integrated on the same packaging substrate (e.g., a two-in-one substrate or a three-in-one substrate or a four-in-one substrate). The plurality of grooves can be prepared according to the position of the light path on the packaging substrate. For example, the grooves are processed in the projection area of the light path in the optical fiber fixing area, so that the end face of the optical fiber fixed in the groove is located on the corresponding light path. In this way, the coupling between the LD chip and the optical fiber can be achieved by simply installing the optical fiber in the groove, thereby facilitating the reduction of the difficulty of active coupling, and even avoiding the need to find the installation position of each optical fiber in the optical fiber fixing area through active coupling, thereby facilitating the reduction of assembly difficulty and assembly cost, and further reducing the cost of the pump laser.

[0130] In some examples, four different types of elements can be integrated on the same substrate. For example, the multi-core substrate-LD and the multi-core substrate-PD introduced above are the same packaging substrate, and a thermistor and a plurality of optical fibers are also fixed on the packaging substrate. The thermistor can be electrically connected to the electrical connector through the electrical interconnection structure in the packaging substrate. In order to facilitate distinction, this packaging substrate is referred to as a four-in-one substrate.

[0131] FIG. 10 schematically shows a possible structure of a pump laser packaged using a four-in-one substrate. For the sake of simplicity of the drawing, FIG. 10 only identifies the refrigerator, the thermistor, and the third laser element (i.e., the PD chip 3 and the LD chip 3), and the annotations and descriptions of other elements can be understood with reference to the related content of FIG. 4, which will not be described herein again. The difference between the laser shown in FIG. 10 and the laser shown in FIG. 9 is that in the laser shown in FIG. 10, the three PD chips, the three LD chips, the thermistor, and the three optical fibers are all mounted on the same packaging substrate (i.e., the four-in-one substrate), and since the thermistor can detect the temperature of the chips by detecting the temperature of the four-in-one substrate, the laser shown in FIG. 10 no longer includes a heat sink substrate. Accordingly, in the assembly process, instead of mounting the three-in-one substrate and the thermistor on the heat sink substrate respectively and then mounting the heat sink substrate on the refrigerator, the four-in-one substrate can be directly mounted on the refrigerator. In this way, it is not only beneficial to reduce the number of substrates in the cavity and reduce the material cost, but also beneficial to reduce the number of assembly times and reduce the assembly cost, and further beneficial to save space in the cavity and integrate more LD chips in the limited size of the cavity to improve the maximum power of the laser output by the laser. Moreover, compared with the three-in-one substrate, the four-in-one substrate for assembling the thermistor will have a larger area, which is not only beneficial to heat dissipation of the chips, but also beneficial to reduce the stress on the chips caused by subsequent packaging and improve the reliability of the PD chips and the LD chips.

[0132] When the optical fiber and the LD chip are fixed on the same packaging substrate (for example, a two-in-one substrate or a three-in-one substrate or a four-in-one substrate), the area on the packaging substrate for fixing the optical fiber can still be referred to as the optical fiber fixing area, which can be understood with reference to the related content introduced above, for example, the optical fiber fixing area can have a plurality of limiting mechanisms, which can be grooves and the like.

[0133] Since the three LD chips are integrated on the same packaging substrate (for example, a two-in-one substrate or a three-in-one substrate or a four-in-one substrate), the positions of the light paths of the forward laser emitted by each of the three LD chips relative to the packaging substrate are fixed. A plurality of grooves can be prepared according to the positions of the light paths on the packaging substrate, for example, grooves are processed in the projection area of the light path in the optical fiber fixing area, so that the end face of the optical fiber fixed in the groove is located on the corresponding light path. In this way, as long as the optical fiber is installed in the groove, the coupling between the LD chip and the optical fiber can be achieved, thereby facilitating the reduction of the difficulty of active coupling, and even avoiding the need to find the installation position of each optical fiber in the optical fiber fixing area through active coupling, thereby facilitating the reduction of assembly difficulty and assembly cost, and further reducing the cost of the pump laser.

[0134] When the optical fiber and the LD chip are fixed on the same packaging substrate (for example, a two-in-one substrate or a three-in-one substrate or a four-in-one substrate), and a plurality of optical fibers are respectively bonded to the multi-core substrate by an adhesive, as shown in FIG. 9 or FIG. 10, the packaging substrate has a groove between the optical fiber fixing area and the plurality of LD chips. In this way, it is beneficial to prevent the adhesive from spreading to the chip end face when the optical fiber is bonded to the optical fiber fixing area of the packaging substrate, thereby avoiding the overflow of the adhesive to the light path of the forward laser or the LD chip, affecting the transmission of the optical signal, and even causing the adhesive to overheat and damage the device.

[0135] Since the thickness of the LD chip is usually close to the diameter of the optical fiber, when the optical fiber and the LD chip are fixed on the same packaging substrate, the optical fiber fixing area and the area (referred to as the LD fixing area) on the substrate for fixing the LD chip can be located on the same plane. When the thickness of the LD chip is different from the diameter of the optical fiber, the plane where the optical fiber fixing area is located can be higher or lower than the plane where the LD fixing area is located.

[0136] The above describes various assembly schemes of the pump laser, and in some examples, different schemes can be combined. For example, the assembly scheme shown in FIG. 2 and the assembly scheme shown in FIG. 4 can be combined.

[0137] For example, the 3 single-core substrates shown in FIG. 2 and the 3 fiber bases and the multi-core substrate-PD shown in FIG. 4 can be used to assemble a pump laser. FIG. 11 schematically shows a possible structure of a pump laser assembled using a multi-core substrate-PD. For the sake of simplicity of the drawing, FIG. 10 only identifies the multi-core substrate-PD, and the annotations and introductions of other elements can be understood with reference to the related contents of FIG. 4 and FIG. 2, which will not be repeated here. The difference between FIG. 11 and FIG. 4 is that the 3 single-core substrates integrated with a single PD chip shown in FIG. 4 are replaced by a multi-core substrate integrated with 3 PD chips. In this way, not only is it beneficial to reduce the number of substrates in the cavity and reduce the material cost, but also it is beneficial to reduce the assembly times and reduce the assembly cost, and it is also beneficial to further save the space in the cavity, integrate more LD chips in the cavity of limited size, and improve the maximum power of the laser output by the laser. Moreover, compared with the single-core substrate, the multi-core substrate-PD has a larger area, which is beneficial not only for chip heat dissipation, but also for reducing the stress on the chip caused by subsequent packaging and improving the reliability of the PD chip.

[0138] For example, the 3 single-core substrates shown in FIG. 2 and the multi-core substrate-PD and the multi-fiber base shown in FIG. 4 can be used to assemble a pump laser. FIG. 12 schematically shows a possible structure of a pump laser in which multiple PD chips and multiple optical fibers are integrated. For the sake of simplicity of the drawing, FIG. 12 only identifies the multi-core substrate-PD and the multi-fiber base for fixing multiple optical fibers, and the annotations and introductions of other elements can be understood with reference to the related contents of FIG. 4 and FIG. 2, which will not be repeated here. The difference between FIG. 12 and FIG. 11 is that the 3 fiber bases shown in FIG. 11 are replaced by a multi-fiber base for fixing 3 optical fibers. In this way, not only is it beneficial to reduce the number of substrates in the cavity and reduce the material cost, but also it is beneficial to reduce the assembly times and reduce the assembly cost, and it is also beneficial to further save the space in the cavity, integrate more LD chips in the cavity of limited size, and improve the maximum power of the laser output by the laser.

[0139] The above respectively introduces examples of assembling a pump laser using a multi-core substrate, a two-in-one substrate, a three-in-one substrate, and a four-in-one substrate. By integrating more laser elements on the packaging substrate, it is beneficial to output a larger power laser by the pump laser without increasing the number of packaging substrates, so as to support the optical amplification module to amplify a larger power optical signal input while meeting the requirements of miniaturization and low cost.

[0140] The above describes the elements used to assemble the pump laser, in practical applications, the pump laser can have more or less elements. For example, more laser elements can be assembled in the pump laser, accordingly, more numbers of LD chips can be integrated on the multi-chip substrate-LD, and / or, more numbers of PD chips can be integrated on the multi-chip substrate-PD. For example, in some scenarios, the elements in the pump laser are not sensitive to temperature, or, the pump laser can be placed on a refrigerator, at this time, the pump laser can not include a thermistor or not include a refrigerator or neither include a thermistor nor include a refrigerator.

[0141] The above describes the scheme of using a multi-chip substrate to assemble a pump laser, the present application does not limit the way of packaging chips on a packaging substrate. Taking an LD chip as an example, the LD chip can be soldered on the packaging substrate by means of eutectic welding, and then the electrodes of the LD chip and the pads on the packaging substrate are connected together by means of gold wire bonding process. The packaging substrate integrated with multiple chips used in the present application can also be called chip on carrier (COC). Only that, one carrier of the COC integrates multiple chips, and, multiple chips of the same type can be packaged on the one carrier, or multiple chips of different types can be packaged on the one carrier.

[0142] The present application does not limit the type of LD chip, for example, the LD chip can be a Raman laser chip.

[0143] The present application does not limit the wavelength of the laser emitted by the LD chip, for example, the wavelength of the laser emitted by the LD chip can be between 1400nm and 1499nm, for example, around 1480nm, or between 900nm and 999nm, for example, around 980nm, or between 1000nm and 1099nm, etc. The wavelengths of the lasers emitted by different LD chips in the same cavity can be the same or different.

[0144] The present application takes the forward end face and the backward end face on the LD chip as an example, the present application does not limit the relative position between the forward end face and the backward end face on the LD chip.

[0145] The foregoing takes the LD chip including two light emitting end faces as an example, in some examples, the LD chip can only include one light emitting end face, and the PD chip can be used to receive the laser reflected from the end face of the optical fiber.

[0146] The drawings of the present application take the butterfly package (such as 14 mini-butterfly package) of the pump laser as an example, and the present application does not limit the package mode of the pump laser, as long as it is beneficial to ensure the reliability of the pump laser. The pump laser provided by the present application can be made into a hermetic package, and can also be made into a non-hermetic package, and the hermeticity of the present application is not limited.

[0147] Optionally, the fixing, mounting and assembling mentioned in the present application can have the same meaning and can be replaced with each other in some cases. The present application does not limit the specific mode of fixing, mounting and assembling, which can be realized by welding or bonding or buckling and the like.

[0148] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method examples, which will not be repeated here. The "A and / or B" involved in the examples of the present application can be understood as including both "A and B" and "A or B".

[0149] In several examples provided by the present application, it should be understood that the disclosed modules or devices or equipment can be realized by other ways. For example, the device examples described above are only schematic. In addition, the coupling or direct coupling or communication connection between the shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, which can be electrical or other forms.

[0150] Finally, it should be pointed out that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the protection scope of the technical solutions of the embodiments of the present application.

Claims

1. A pump laser, characterized by The pump laser comprises a shell with a cavity inside, a packaging substrate and a plurality of optical fibers, the shell is further provided with an electrical connector and an optical fiber tail pipe, the packaging substrate is assembled in the cavity, and the plurality of optical fibers respectively extend from the outside of the shell to the inside of the cavity through the optical fiber tail pipe; A plurality of laser diode (LD) chips are integrated on the packaging substrate, the plurality of LD chips are electrically connected to the electrical connector through the packaging substrate, and the plurality of LD chips are used for respectively receiving driving signals from the electrical connector and emitting a plurality of laser beams under the driving of the driving signals. End faces of the plurality of optical fibers are respectively located on the optical paths of the plurality of laser beams, and the plurality of optical fibers are used for transmitting the plurality of laser beams to the outside of the shell.

2. The pump laser according to claim 1, characterized in that, The packaging substrate is provided with a plurality of LD pads, the plurality of LD pads are connected to the electrical connector through an electrical interconnection structure in the packaging substrate.

3. The pump laser according to claim 1 or 2, characterized in that The plurality of LD pads are located in a region between the plurality of LD chips and the electrical connector on the packaging substrate.

4. The pump laser according to any one of claims 1 to 3, characterized in that The plurality of optical fibers are respectively fixed on optical fiber fixing regions on the packaging substrate.

5. The pump laser according to claim 4, characterized in that The optical fiber fixing regions are provided with a plurality of limiting mechanisms for respectively fixing the plurality of optical fibers, and the end faces of the plurality of optical fibers after being fixed are respectively located on the optical paths of the plurality of laser beams.

6. The pump laser according to claim 5, characterized in that The plurality of limiting mechanisms are a plurality of grooves on the surface of the packaging substrate, and the plurality of grooves are respectively located in projection regions of the optical paths of the plurality of laser beams on the surface of the packaging substrate, and the plurality of optical fibers are respectively installed in the plurality of grooves.

7. The pump laser according to any of claims 4-6, characterized in that, The plurality of optical fibers are bonded to the optical fiber fixing regions by an adhesive, and the packaging substrate is provided with a groove between the optical fiber fixing regions and the plurality of LD chips for accommodating the overflowed adhesive.

8. The pump laser according to any of claims 1-7, characterized in that, A plurality of photodiode (PD) chips are further integrated on the packaging substrate, the plurality of PD chips are electrically connected to the electrical connector through the packaging substrate, and the plurality of PD chips are used for converting a plurality of optical signals received from the plurality of LD chips into a plurality of electrical signals and outputting the plurality of electrical signals to the electrical connector.

9. The pump laser according to claim 8, characterized in that At least two PD chips in the plurality of PD chips are connected in parallel to the same PD pad on the packaging substrate, and the PD pad is directly connected to the electrical connector.

10. The pump laser according to any of claims 1-9, characterized in that, A temperature detection element is further integrated on the packaging substrate, the temperature detection element is electrically connected to the electrical connector through the packaging substrate, and the temperature detection element is used for detecting the temperature of the packaging substrate and outputting a detection result to the electrical connector.

11. A pump laser, characterized by The pump laser comprises a shell with a cavity inside, a packaging substrate, a plurality of laser diode chips and a plurality of optical fibers, the shell is provided with an electrical connector and an optical fiber tail pipe, the packaging substrate and the plurality of laser diode chips are assembled in the cavity, and the plurality of optical fibers respectively extend from the outside of the shell to the inside of the cavity through the optical fiber tail pipe; The plurality of LD chips are electrically connected to the electrical connector respectively, and are configured to receive driving signals from the electrical connector respectively and emit a plurality of laser beams under the driving of the driving signals; End faces of the plurality of optical fibers are located on optical paths of the plurality of laser beams respectively, and the plurality of optical fibers are configured to transmit the plurality of laser beams to outside of the shell; A plurality of photodiode (PD) chips are integrated on the packaging substrate, the plurality of PD chips are electrically connected to the electrical connector through the packaging substrate, and the plurality of PD chips are configured to convert a plurality of optical signals received from the plurality of LD chips into a plurality of electrical signals and output the plurality of electrical signals to the electrical connector.

12. An optical amplification module, characterized by comprising: The optical amplification module comprises one or more gain optical fibers and the pump laser as claimed in any one of claims 1-11. The pump laser is configured to input a laser beam to the one or more gain optical fibers. The one or more gain optical fibers are configured to transmit an optical signal received by the optical amplification module and amplify signal strength of the optical signal under excitation of the laser beam.

13. An optical amplification system characterized by comprising: The system comprises a sending module and the optical amplification module as claimed in claim 12. The sending module is configured to send an optical signal to the optical amplification module. The optical amplification module is configured to receive the optical signal, amplify signal strength of the optical signal, and output the amplified optical signal.

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