A tunable laser device and optical communication module

Abstract

The application relates to the technical field of optical communication, in particular to a tunable laser device and an optical communication module. The tunable laser device comprises a shell, a semiconductor refrigerator, a laser gain chip, a collimating lens, a mirror, a filter and a fiber coupling lens; the semiconductor refrigerator has a cold surface, the laser gain chip is attached to a first region of the cold surface, the filter is attached to a second region of the cold surface, the collimating lens is arranged on the light emitting side of the laser gain chip, the mirror is arranged on the side of the collimating lens away from the laser gain chip, the filter is arranged on the side of the mirror away from the collimating lens, and the fiber coupling lens is arranged on the side of the filter away from the mirror.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a tunable laser device and an optical communication module. Background Technology

[0002] Tunable laser devices are core light source components in optical communication systems and are widely used in dense wavelength division multiplexing systems, fiber optic sensor networks, and coherent optical communication. By adjusting the output wavelength to adapt to different channel requirements, they are key devices for achieving high-speed, high-capacity optical transmission.

[0003] Existing tunable laser devices exhibit significant differences in heat generation and heat dissipation requirements among components such as laser gain chips and filters during operation. Therefore, how to provide a tunable laser device capable of differentiated temperature control based on the heat dissipation requirements of each component, in order to reduce thermal crosstalk and improve cooling efficiency, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0004] This invention provides a tunable laser device and an optical communication module to solve the above-mentioned problems.

[0005] This invention discloses a tunable laser device, including a housing, a semiconductor cooler, a laser gain chip, a collimating lens, a reflector, a filter, and a fiber optic coupling lens; the semiconductor cooler has a cold surface, the laser gain chip is mounted on a first region of the cold surface, the filter is mounted on a second region of the cold surface, the collimating lens is disposed on the light-emitting side of the laser gain chip, the reflector is disposed on the side of the collimating lens away from the laser gain chip, the filter is disposed on the side of the reflector away from the collimating lens, and the fiber optic coupling lens is disposed on the side of the filter away from the reflector;

[0006] The thermoelectric cooler includes multiple thermoelectric columns distributed below the cold surface. The density of each thermoelectric column varies in different regions on the cold surface, wherein the density of the thermoelectric columns below the first region is greater than the density of the thermoelectric columns below the second region.

[0007] Optionally, a gold-plated layer or gold-plated pattern is provided on the first area of ​​the cold surface, and the laser gain chip is mounted on the gold-plated layer or gold-plated pattern by conductive silver paste or solder balls.

[0008] Optionally, the tunable laser device also includes a carrier, on which a laser gain chip is mounted, and the carrier is mounted on a first region of the cold surface. A positioning groove is formed on the carrier, and a reflector is assembled in the positioning groove.

[0009] Optionally, the reflector is made of glass or silicon. The side of the reflector facing the collimating lens is coated with a beam-splitting film. The beam-splitting film is configured to reflect a portion of the incident beam back to the laser gain chip to form a laser resonant cavity, while the other portion is transmitted back to the filter. The side of the reflector facing away from the collimating lens is coated with an anti-reflection film.

[0010] Optionally, the filter is vertically mounted on the second area of ​​the cold surface, and the filter is equipped with a heating wire. The operating temperature of the filter is adjusted by providing different currents to the heating wire.

[0011] Optionally, the filter includes multiple filters, which are sequentially arranged between the reflector and the fiber optic coupling lens along the optical path, and the operating temperature of each filter is independently adjustable.

[0012] Optionally, the tunable laser device also includes a beam splitter prism, an isolator, a base, and an optical power monitoring chip. The beam splitter prism and the isolator are integrated into a single component by optical path adhesive. The beveled surface of the beam splitter prism is coated with a beam splitting film. The base is mounted on the cold surface, and the beam splitter prism is mounted on the base. The optical power monitoring chip is mounted on the cold surface and located inside the base. The isolator is located on the optical end face of the beam splitter prism away from the filter. The fiber optic coupling lens is located on the side of the isolator away from the beam splitter prism.

[0013] Optionally, the beam splitter is formed by bonding two triangular beam splitters together with optical path adhesive. The inclined surface of the beam splitter is configured to reflect a portion of the light to the optical power monitoring chip to achieve backlight monitoring, while the remaining light is transmitted through an isolator and an optical fiber coupling lens before entering the pigtail assembly.

[0014] Optionally, the housing has a through hole, the fiber optic coupling lens is mounted in the through hole, and the housing has pins on the side.

[0015] The present invention also discloses an optical communication module, including the above-mentioned tunable laser device.

[0016] The beneficial effects of the tunable laser device provided in this invention are as follows: By setting semiconductor thermoelectric pillars with varying density in zones below the cold surface of the semiconductor cooler, the density of thermoelectric pillars below the first region where the laser gain chip is mounted is greater than the density of thermoelectric pillars below the second region where the filter is mounted. This enables differentiated temperature control for the heat dissipation needs of different components, effectively solving the problem of thermal crosstalk caused by the lateral diffusion of heat from high-heat-generating components to low-heat-generating areas due to the uniform distribution of thermoelectric pillars in the semiconductor cooler in the prior art. At the same time, by concentrating more thermoelectric pillars in high-heat-generating areas and reducing the number of thermoelectric pillars in low-heat-generating areas, the cooling power distribution of the semiconductor cooler is more precise and reasonable, avoiding unnecessary energy loss and significantly improving the cooling energy efficiency. Attached Figure Description

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of a tunable laser device according to an embodiment of the present invention; Figure 2 This is an internal schematic diagram of the tunable laser device according to an embodiment of the present invention; Figure 3 This is another internal schematic diagram of the tunable laser device according to an embodiment of the present invention; Figure 4 This is another internal schematic diagram of the tunable laser device according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a semiconductor cooler according to an embodiment of the present invention.

[0018] The labels for the attached figures are as follows: 1. Housing; 2. Semiconductor cooler; 21. First region; 22. Second region; 23. Semiconductor thermoelectric column; 4. Laser gain chip; 5. Collimating lens; 6. Mirror; 7. Filter; 71. Heating wire; 8. Fiber optic coupling lens; 9. Carrier; 10. Beam splitter prism; 101. Triangular beam splitter prism; 20. Isolator; 30. Base; 40. Optical power monitoring chip; 50. Pigtail assembly; 60. Pin. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] This invention provides a tunable laser device, such as... Figures 1 to 5 As shown, the tunable laser device includes a housing 1, a semiconductor cooler 2, a laser gain chip 4, a collimating lens 5, a reflector 6, a filter 7, and a fiber optic coupling lens 8. The semiconductor cooler 2 has a cold surface. The laser gain chip 4 is mounted on a first region 21 of the cold surface, the filter 7 is mounted on a second region 22 of the cold surface, the collimating lens 5 is disposed on the light-emitting side of the laser gain chip 4, the reflector 6 is disposed on the side of the collimating lens 5 away from the laser gain chip 4, the filter 7 is disposed on the side of the reflector 6 away from the collimating lens 5, and the fiber optic coupling lens 8 is disposed on the side of the filter 7 away from the reflector 6.

[0021] The semiconductor cooler 2 includes multiple semiconductor thermoelectric columns 23 distributed below the cold surface. The density of each semiconductor thermoelectric column 23 varies in different regions on the cold surface. The density of the semiconductor thermoelectric columns 23 below the first region 21 is greater than the density of the semiconductor thermoelectric columns 23 below the second region 22.

[0022] The tunable laser device of the present invention provides thermoelectric pillars 23 with varying density in zones below the cold surface of the thermoelectric cooler 2. This results in a higher density of thermoelectric pillars below the first region 21 where the laser gain chip 4 is mounted than below the second region 22 where the filter 7 is mounted. This allows for differentiated temperature control based on the heat dissipation requirements of different components. It effectively solves the problem of thermal crosstalk caused by the lateral diffusion of heat from high-heat-generating components to low-heat-generating regions due to the uniform distribution of thermoelectric pillars in the thermoelectric cooler 2 in the prior art. Furthermore, by concentrating more thermoelectric pillars in high-heat-generating regions and reducing the number of thermoelectric pillars in low-heat-generating regions, the cooling power distribution of the thermoelectric cooler 2 is more precise and reasonable, avoiding unnecessary energy loss and significantly improving the cooling energy efficiency.

[0023] Specifically, the outer shell 1 serves as the overall packaging structure of the device, providing mechanical support and physical protection for the internal components, while forming a sealed working environment to isolate external dust, moisture and other interference factors, ensuring the stability of laser output and the service life of the device.

[0024] The semiconductor cooler 2 is the core temperature control component of the device. It achieves active cooling based on the Peltier effect. By passing a direct current through the semiconductor thermoelectric pillars 23, the cold surface absorbs heat, thus providing a precise and stable low-temperature operating environment for the laser gain chip 4 and filter 7 mounted on it. The density partitioning design of the semiconductor thermoelectric pillars 23 allows the cooling power to be differentiated according to the actual heat load of different components, effectively suppressing lateral heat diffusion and improving overall cooling efficiency. The laser gain chip 4 is an active device for laser generation. It contains a gain medium and achieves population inversion and stimulated emission under the excitation of an external pump current, which is the energy source for laser output. At the same time, it generates a lot of heat during operation, so there is a high heat dissipation requirement for the high-density thermoelectric pillar arrangement in the first region 21 of the cold surface. The collimating lens 5 is located on the light-emitting side of the laser gain chip 4. Its function is to collimate the diverging beam emitted by the laser gain chip 4 and convert the beam into approximately parallel light to reduce propagation loss in the subsequent optical path and ensure beam quality, thus providing an ideal beam shape for the efficient operation of the reflector 6 and the filter 7.

[0025] The reflector 6 is positioned on the side of the collimating lens 5 away from the laser gain chip 4. Its function is to reflect the beam collimated by the collimating lens 5, changing the direction of the optical path and guiding the beam to the filter 7. This achieves optical path folding and spatial layout optimization, helping to reduce the overall size of the device. The filter 7 is mounted on the second region 22 of the cold surface. Its function is to select the wavelength of the beam guided by the reflector 6, allowing only specific wavelengths or narrow bands of optical signals to pass through, thereby achieving tunable laser wavelength output. It is a key optical component for achieving the wavelength tuning function of the device. Its operational stability is relatively sensitive to temperature, but its heat generation is relatively low, thus it is suitable for the second region 22 with low thermoelectric column density. The fiber coupling lens 8 is positioned on the side of the filter 7 away from the reflector 6. Its function is to focus the laser beam after frequency selection by the filter 7 and efficiently couple the focused beam into the external optical fiber, realizing the conversion and transmission of the laser signal from free space to the fiber waveguide, ensuring coupling efficiency and reducing insertion loss.

[0026] Specifically, a gold-plated layer or gold-plated pattern is provided on the first region 21 of the cold surface. The laser gain chip 4 is mounted on the gold-plated layer or gold-plated pattern by conductive silver paste or solder ball soldering. By providing a gold-plated layer or gold-plated pattern on the first region 21 of the cold surface and mounting the laser gain chip 4 on it by conductive silver paste or solder ball soldering, the excellent conductivity and thermal conductivity of the gold plating layer are effectively reduced, thereby reducing the contact thermal resistance between the chip and the cold surface. This allows the heat generated by the laser gain chip 4 to be efficiently transferred to the semiconductor cooler 2. At the same time, the conductive silver paste or solder ball soldering method takes into account both the mechanical fixation and electrical connection requirements, ensuring that a reliable conductive path is formed between the working electrode of the laser gain chip 4 and the external driving circuit, thus improving the heat dissipation efficiency and electrical connection stability of the device.

[0027] The semiconductor thermoelectric pillars 23 are the core functional components of the semiconductor cooler 2. They are columnar structures made of thermoelectric semiconductor materials such as bismuth telluride (Bi2Te3). Through doping, both P-type and N-type semiconductor thermoelectric pillars 23 are formed, arranged in pairs to form a thermocouple unit. The semiconductor thermoelectric pillars 23 operate based on the Peltier effect. When a direct current passes through the thermocouple composed of P-type and N-type semiconductor thermoelectric pillars 23, energy migration occurs at the junction interface of the two materials, resulting in heat absorption at one end (forming a cold junction) and heat release at the other end (forming a hot junction). By controlling the current flow direction, the cooling or heating mode can be switched.

[0028] In this invention, each semiconductor thermoelectric pillar 23 is mechanically supported and electrically insulated by a ceramic substrate (typically alumina or aluminum nitride ceramic) on its cold and hot surfaces. The two ends of the thermoelectric pillar are connected to a metal conductive layer on the ceramic substrate via welding or conductive adhesive, forming a complete thermoelectric circuit. An external pin 60 is connected to the metal conductive layer and is used to input DC drive current.

[0029] The gold plating layer can be formed on a specific area of ​​the ceramic substrate on the cold side using electrolytic or chemical gold plating processes. The thickness of the gold plating layer is usually controlled within the range of 0.5 micrometers to 3 micrometers to balance conductivity and cost. The gold plating pattern can be customized according to the pad layout of the laser gain chip 4, including chip mounting pads, grounding pads, and wire bonding pads. The pads are electrically interconnected through gold-plated wire patterns. High thermal conductivity silver paste can be selected for conductive silver paste. Solder ball soldering can be carried out using 3D flying soldering process, which achieves metallurgical connection between chip pads and gold-plated pads by precisely controlling the melting state of the solder balls.

[0030] Furthermore, the tunable laser device also includes a carrier 9, on which the laser gain chip 4 is mounted. The carrier 9 is mounted on the first region 21 of the cold surface, and a positioning groove is formed on the carrier 9, within which the reflector 6 is assembled. By adding the carrier 9, mounting the laser gain chip 4 onto the carrier 9, and then mounting the entire carrier 9 onto the first region 21 of the cold surface, while simultaneously forming a positioning groove on the carrier 9 for the assembly of the reflector 6, integrated packaging of the laser gain chip 4 and the reflector 6 is achieved. The carrier 9, as an intermediate support structure, not only provides a thermal conduction interface between the laser gain chip 4 and the cold surface, but also provides a precise mechanical positioning reference for the reflector 6 through the positioning groove, effectively ensuring the relative positional accuracy between the reflector 6 and the laser gain chip 4, thereby ensuring the optical alignment accuracy of the laser resonator and improving the stability and beam quality of the laser output.

[0031] In one embodiment, the carrier 9 can be made of a ceramic material or metal composite material with high thermal conductivity, such as aluminum nitride ceramic or copper-tungsten alloy, whose coefficient of thermal expansion matches the substrate material of the laser gain chip 4 to reduce thermal stress caused by temperature changes; a gold-plated layer can be provided on the side of the carrier 9 facing the cold surface, and it can be mounted and fixed to the first area 21 of the TEC cold surface by conductive silver paste or solder paste; the side of the carrier 9 facing away from the cold surface is used to support the laser gain chip 4; a positioning groove is opened on the side of the carrier 9 away from the light-emitting end of the laser gain chip 4, and the width of the positioning groove is adapted to the thickness of the reflector 6, usually the groove width is 0.01 mm to 0.05 mm larger than the thickness of the reflector 6, so as to facilitate the insertion and assembly of the reflector 6; the depth of the positioning groove is designed according to the required optical height of the reflector 6, so that the reflective surface of the reflector 6 is exactly located on the light-emitting optical axis of the laser gain chip 4 after assembly; the reflector 6 can be bonded and fixed in the positioning groove by UV curing adhesive or low-temperature epoxy adhesive.

[0032] The reflector 6 is made of glass or silicon. The side of the reflector 6 facing the collimating lens 5 is coated with a beam-splitting film. This film is configured to reflect a portion of the incident beam back to the laser gain chip 4 to form a laser resonant cavity, while the other portion is transmitted through the film to the filter 7. The side of the reflector 6 facing away from the collimating lens 5 is coated with an anti-reflection film. The precise design of the beam-splitting film splits the incident beam into reflected and transmitted light in a predetermined ratio. The reflected light returns to the laser gain chip 4 to form a laser resonant cavity to maintain stimulated oscillation, while the transmitted light continues to be transmitted to the filter 7. This achieves optical path connection between the laser resonant cavity and the wavelength selection system. Simultaneously, the anti-reflection film on the back surface effectively reduces Fresnel reflection loss on the rear surface of the reflector 6, improving light energy utilization and reducing stray light interference caused by back reflection.

[0033] The glass material can be optical-grade fused silica or BK7 optical glass, which has a low coefficient of thermal expansion and high optical uniformity. Silicon material has the advantage of being compatible with semiconductor processes, making it easy to realize micro-nano structure processing. The beam splitter is a multilayer dielectric film system, and the film system is designed according to the lasing characteristics of the laser gain chip 4. For example, when the gain chip requires about 6% of the reflected light energy for reciprocating reflection to achieve maximum lasing, the beam splitter is configured with 6% reflectivity and 94% transmittance. The film system is usually composed of titanium dioxide and silicon dioxide thin films with alternating high and low refractive indices. The antireflection film is also a multilayer dielectric film system.

[0034] Specifically, the filter 7 is vertically mounted on the second region 22 of the cold surface. The filter 7 is equipped with a heating wire 71, and the operating temperature of the filter 7 is adjusted by providing different currents to the heating wire 71. Utilizing the temperature tuning characteristics of the filter 7, the transmission peak wavelength is shifted by changing the temperature of the filter 7, thereby achieving precise selection and tuning of the laser output wavelength. The vertical mounting method ensures that the optical surface of the filter 7 is perpendicular to the optical axis, guaranteeing normal beam incidence and reducing polarization-dependent losses. Simultaneously, the filter 7 is mounted in the second region 22, where the thermoelectric column density is low, avoiding excessive conflict between the heat generated by the heating wire 71 and the TEC cooling function, which is beneficial for maintaining the accuracy of temperature tuning and response speed.

[0035] In an optional embodiment, the filter 7 is a thin-film interference filter or a volume Bragg grating filter, whose transmission peak wavelength exhibits a linear or approximately linear shift with temperature. When the filter 7 is mounted vertically, the angle between the normal of its optical surface and the beam propagation direction is controlled within ±1° to ensure that the beam is incident normally and to reduce the transmission peak shift caused by angular mismatch. The heating wire 71 can be made of platinum resistance wire or nickel-chromium alloy wire, which is deposited on the side or back of the filter 7 by sputtering or photolithography. The resistance value of the heating wire 71 is usually 50 ohms to 200 ohms. The temperature of the filter 7 can be continuously adjusted by changing the applied current or by using pulse width modulation. The pads of the filter 7 are bonded and fixed to the gold-plated pads on the second area 22 of the cold side using conductive silver paste or solder balls to achieve electrical connection. After welding, the gap between the bottom surface of the filter 7 and the cold side is controlled within 0.05 mm to reduce thermal resistance and improve temperature response speed. Thermal grease or thermal pads can also be filled between the filter 7 and the cold side to further improve thermal contact and ensure temperature uniformity.

[0036] Specifically, the filter 7 comprises multiple filters, which are sequentially arranged between the reflector 6 and the fiber coupling lens 8 along the optical path. The operating temperature of each filter 7 is independently adjustable. By cascading multiple filters 7 and utilizing the independent drift characteristics of the transmission peak wavelength of each filter 7 at different temperatures, a finer wavelength resolution and a wider tuning range are achieved. The cascaded transmission characteristics of multiple filters 7 are equivalent to an equivalent multi-cavity etalon, and the full width at half maximum (FWHM) of its synthesized transmission peak is significantly narrower than that of a single filter 7, thereby improving the accuracy of wavelength selection. At the same time, the independent temperature control of each filter 7 greatly enhances the tuning flexibility, enabling precise locking of the wavelength of any channel in a dense wavelength division multiplexing system.

[0037] More specifically, the number of filters 7 is usually 2 to 4, preferably 3. Each filter 7 is arranged at equal or unequal intervals along the optical path direction. Each sub-region can be isolated by heat insulation grooves or low thermal conductivity materials to reduce thermal crosstalk between filters 7 and ensure the independence of temperature tuning of each filter 7.

[0038] Furthermore, the tunable laser device also includes a beam splitter 10, an isolator 20, a base 30, and an optical power monitoring chip 40. The beam splitter 10 and the isolator 20 are integrated into a single component by optical path adhesive bonding. The inclined surface of the beam splitter 10 is coated with a beam splitting film. The base 30 is mounted on the cold surface, and the beam splitter 10 is mounted on the base 30. The optical power monitoring chip 40 is mounted on the cold surface and located inside the base 30. The isolator 20 is located on the optical end face of the beam splitter 10 away from the filter 7, and the fiber optic coupling lens 8 is located on the side of the isolator 20 away from the beam splitter 10. Through the optical path adhesive bonding integration of the beam splitter 10 and the isolator 20, the support of the beam splitter 10 by the base 30, the mounting layout of the optical power monitoring chip 40 inside the base 30, and the sequential optical path arrangement of the isolator 20 and the fiber optic coupling lens 8, modular integration of backlight monitoring, optical isolation, and fiber optic coupling functions is achieved. The integrated packaging of the beam splitter prism 10 and the isolator 20 significantly reduces the axial dimensions and internal space occupied by the device. The base 30 has a U-shaped or frame-shaped structure, which provides a stable mechanical support platform for the beam splitter prism 10. At the same time, its internal space provides shielding protection for the optical power monitoring chip 40, avoiding interference from external stray light on the backlight monitoring accuracy. The isolator 20 effectively prevents mode jumps and noise increases caused by reflected light returning to the laser resonant cavity, thus improving the stability of laser output.

[0039] The optical path adhesive between the beam splitter 10 and the isolator 20 is a UV-curable optical adhesive or a low-temperature thermosetting optical adhesive. Its refractive index matches the refractive index of the materials of the beam splitter 10 and the isolator 20. After curing, the adhesive layer has low stress, high light transmittance, and good temperature resistance. The base 30 is made of a metal or ceramic material with high thermal conductivity, such as Kovar alloy or aluminum nitride ceramic. Its coefficient of thermal expansion matches the cold-side ceramic substrate. The side of the base 30 facing the cold side has a gold-plated layer, and it is mounted and fixed to the cold side by conductive silver paste or solder paste. The base 30 has a U-shaped structure or a rectangular frame structure, and its internal cavity size is slightly larger than the optical power. The package size and cavity depth of the power monitoring chip 40 are designed according to the height of the photosensitive surface of the power monitoring chip 40, so that the photosensitive surface of the chip is exactly located at the focusing position of the reflected light from the inclined surface of the beam splitter 10. The power monitoring chip 40 can be a photodiode chip with its photosensitive surface facing the inclined surface of the beam splitter 10, and is electrically connected to the lead pads on the base 30 by gold wire bonding. The isolator 20 can be a magneto-optical isolator, whose core components are a magneto-optical crystal and a permanent magnet. The optical end face of the isolator 20 is coated with an anti-reflection film, and the end face that is attached to the beam splitter 10 and the end face that is docked with the fiber optic coupling lens 8 are both precision polished.

[0040] Specifically, the beam splitter 10 is formed by bonding two triangular beam splitters 101 together with optical adhesive. The inclined surface of the beam splitter 10 is configured to reflect a portion of the light to the optical power monitoring chip 40 for backlight monitoring, while the remaining light passes through the isolator 20 and the fiber optic coupling lens 8 before entering the pigtail assembly 50. By gluing the inclined surfaces of two triangular prisms together to form a cube or cuboid structure, the inclined surfaces serve as a beam splitting interface to achieve precise beam splitting. The reflected light is guided at a specific angle to the optical power monitoring chip 40 located inside the base 30, enabling real-time monitoring and feedback control of the output optical power. The transmitted light continues to propagate along the main optical path, and after passing through the isolator 20, it is focused and coupled into the pigtail assembly 50 by the fiber coupling lens 8. The entire optical path is compact and the functional modules are smoothly connected, significantly improving the integration and packaging efficiency of the device.

[0041] Specifically, the two triangular beam splitters 101 are isosceles right-angled triangular prisms or custom-shaped triangular prisms tailored to the beam splitting angle requirements. They are made of optical-grade fused silica or optical glass, and the beveled surfaces of the two prisms are precision polished. The optical path adhesive is an optical adhesive with a matching refractive index, which cures under ultraviolet light or heating after bonding. The beam splitting film on the beveled surface of the beam splitter 10 is a partially reflective and partially transmissive film. The reflection ratio is designed according to the backlight monitoring sensitivity requirements, typically 2% reflection and 98% transmission, or 5% reflection and 95% transmission. After the triangular beam splitter 101 is attached, among its four right-angled end faces, the end face facing the filter 7 is the incident end face, the end face facing the isolator 20 is the transmission and emission end face, and the end face facing the optical power monitoring chip 40 is the reflection and emission end face. Each end face is coated with an anti-reflection film. The reflected light is reflected from the inclined plane and propagates downward, passing through the internal space of the base 30 to reach the photosensitive surface of the optical power monitoring chip 40. The length of the reflected light path is optimized according to the size of the chip photosensitive surface and the divergence angle of the reflected light to ensure that the reflected light spot completely covers the chip photosensitive surface. The transmitted light passes through the isolator 20 and the fiber coupling lens 8 in sequence, and is focused into the single-mode fiber or multimode fiber in the pigtail assembly 50.

[0042] Specifically, the housing 1 has a through hole, and the fiber optic coupling lens 8 is mounted inside the through hole. The housing 1 also has pins 60 on its side. By creating a through hole in the housing 1 and mounting the fiber optic coupling lens 8 inside it, while simultaneously providing pins 60 on the side of the housing 1, the through hole serves as the assembly reference for the fiber optic coupling lens 8. The inner wall of the through hole provides radial positioning and axial limiting for the lens, making the lens assembly more robust and reliable. This effectively resists positional movement caused by external vibration and temperature cycling, ensuring the long-term stability of fiber optic coupling efficiency. The side pins 60 design facilitate the insertion and connection of the device to an external circuit board, simplifying the integration and installation process of the device in the optical communication system and improving production efficiency and system reliability.

[0043] Pin 60 is connected to the electrode pads of the laser gain chip 4 mounted on the carrier 9 via gold wire bonding or conductive silver paste. This connection transmits the drive current and feedback signal of the gain chip, enabling pumping and power regulation of the laser output. Pin 60 is also electrically connected to the thermoelectric column array of the semiconductor cooler 2 via wires or conductive silver paste, providing DC drive current to the semiconductor cooler 2 and achieving cooling of the cold surface based on the Peltier effect. Pin 60 is also connected to the heating wire 71 pads on the filter 7 via conductive silver paste or solder ball bonding, providing adjustable current to the heating wire 71 to independently control the operating temperature of the filter 7, thereby achieving laser wavelength tuning. Pin 60 is also connected to the electrodes of the optical power monitoring chip 40 mounted inside the base 30 via gold wire bonding, receiving the photocurrent signal generated by the optical power monitoring chip 40 due to backlight reflection. This signal is fed back to the external drive circuit to achieve closed-loop monitoring and stabilization of the output optical power.

[0044] The outer casing 1 is made of metal stamping or precision casting, and the material is Kovar alloy, stainless steel, or aluminum alloy. Through holes are formed on the end face or side of the outer casing 1. The through holes are circular or rectangular, and their diameter is designed according to the outer diameter or overall dimensions of the fiber optic coupling lens 8 to facilitate insertion and assembly while ensuring fitting accuracy. A stepped structure or annular groove can be provided on the inner wall of the through hole for axial positioning of the fiber optic coupling lens 8. The step height is precisely calculated based on the focal length of the lens and the docking position of the pigtail assembly 50, ensuring that the focal point of the lens is precisely located at the core layer of the fiber end face. The fiber optic coupling lens 8 can be a spherical lens, an aspherical lens, or a gradient refractive index lens. The fiber optic coupling lens 8 is bonded and fixed to the through hole using UV-curable adhesive or low-temperature epoxy adhesive. The adhesive layer fills the gap between the outer wall of the lens and the inner wall of the through hole, forming a strong mechanical connection after curing. The pins 60 are metal needle-shaped pins made of copper alloy or iron-nickel alloy, with a tin or gold plating layer on the surface to improve solderability and oxidation resistance. The number of pins 60 is determined according to the electrical interface requirements of the device. Pin 60 extends horizontally or bends vertically from the side of housing 1 to facilitate through-hole soldering or surface mount soldering to printed circuit boards.

[0045] Specifically, in the technical solution of this invention, a gold-plated layer or gold-plated pattern is provided on the cold surface of the semiconductor cooler 2. The laser gain chip 4 and the filter 7 are both mounted on the cold surface through the gold-plated layer or gold-plated pattern, ensuring good thermal conductivity and electrical connection performance. The laser gain chip 4 is mounted on a carrier 9, which is then mounted on the first region 21 of the cold surface. A positioning groove is provided on the carrier 9, and a reflector 6 is assembled in the positioning groove. A collimating lens 5 is mounted on the carrier 9, so that the laser gain chip 4, the collimating lens 5, and the reflector 6 form a compact and integrated laser resonant cavity structure. The reflector 6 is made of glass or silicon. The side facing the collimating lens 5 is coated with a beam-splitting film, and the side facing away from the collimating lens 5 is coated with an anti-reflection film. The beam-splitting film reflects part of the incident beam back to the laser gain chip 4 to excite secondary and multiple lasings, while the other part is transmitted to the filter 7. The filter 7 is vertically mounted on the second region 22 of the cold surface, and its pads are soldered to the cold surface using conductive silver paste or solder balls. The gold-plated pads on the surface are connected. The filter 7 is equipped with a heating wire 71. By providing different currents to the heating wire 71, the operating temperature of the filter 7 is adjusted to complete wavelength selection. Multiple filters 7 are arranged sequentially along the optical path, and the operating temperature of each filter 7 is independently adjustable, forming a multi-level wavelength selection system. The beam splitter 10 is formed by bonding two triangular beam splitters 101 together with optical path adhesive. Its inclined surface is coated with a beam splitting film. The isolator 20 is attached to the optical end face of the beam splitter 10 away from the filter 7 with optical path adhesive. The base 30 is attached to the cold surface. The beam splitter 10 is attached to the base 30. The optical power monitoring chip 40 is attached to the cold surface and located inside the base 30. The inclined surface of the beam splitter 10 reflects part of the light to the optical power monitoring chip 40 to achieve backlight monitoring. The remaining light is transmitted and passes through the isolator 20 and the fiber optic coupling lens 8 in sequence to enter the pigtail assembly 50. The fiber optic coupling lens 8 is attached to the through hole of the housing 1. The side of the housing 1 is provided with pins 60. The overall structure is compact and the assembly is firm and reliable.

[0046] The present invention also discloses an optical communication module, including the tunable laser device as described above. In addition to the tunable laser device, the optical communication module also includes a driver circuit board, a temperature control circuit board, and a pigtail assembly 50.

[0047] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A tunable laser device, characterized in that, The device includes a housing, a semiconductor cooler, a laser gain chip, a collimating lens, a reflector, a filter, and a fiber optic coupling lens. The semiconductor cooler has a cold surface. The laser gain chip is mounted on a first region of the cold surface, the filter is mounted on a second region of the cold surface, the collimating lens is disposed on the light-emitting side of the laser gain chip, the reflector is disposed on the side of the collimating lens away from the laser gain chip, the filter is disposed on the side of the reflector away from the collimating lens, and the fiber optic coupling lens is disposed on the side of the filter away from the reflector. The semiconductor cooler includes a plurality of semiconductor thermoelectric columns distributed below the cold surface. The density of each semiconductor thermoelectric column varies in zones on the cold surface, wherein the density of the semiconductor thermoelectric columns below the first zone is greater than the density of the semiconductor thermoelectric columns below the second zone.

2. The tunable laser device according to claim 1, characterized in that, The first area of ​​the cold surface is provided with a gold-plated layer or a gold-plated pattern, and the laser gain chip is mounted on the gold-plated layer or the gold-plated pattern by conductive silver paste or solder balls.

3. The tunable laser device according to claim 1, characterized in that, The tunable laser device further includes a carrier, the laser gain chip is mounted on the carrier, the carrier is mounted on the first region of the cold surface, the carrier has a positioning groove, and the reflector is assembled in the positioning groove.

4. The tunable laser device according to claim 3, characterized in that, The reflector is made of glass or silicon. The side of the reflector facing the collimating lens is coated with a beam-splitting film. The beam-splitting film is configured to reflect a portion of the incident beam back to the laser gain chip to form a laser resonant cavity, and transmit the other portion to the filter. The side of the reflector facing away from the collimating lens is coated with an anti-reflection film.

5. The tunable laser device according to any one of claims 1 to 4, characterized in that, The filter is vertically attached to the second region of the cold surface. The filter is equipped with a heating wire, and the operating temperature of the filter is adjusted by providing different currents to the heating wire.

6. The tunable laser device according to claim 5, characterized in that, The filter includes multiple filters, which are sequentially arranged between the reflector and the fiber optic coupling lens along the optical path direction, and the operating temperature of each filter is independently adjustable.

7. The tunable laser device according to any one of claims 1 to 4, characterized in that, The tunable laser device further includes a beam splitter prism, an isolator, a base, and an optical power monitoring chip. The beam splitter prism and the isolator are integrated into a single component by optical path adhesive. The inclined surface of the beam splitter prism is coated with a beam splitting film. The base is attached to the cold surface, and the beam splitter prism is attached to the base. The optical power monitoring chip is attached to the cold surface and located inside the base. The isolator is disposed on the optical end face of the beam splitter prism away from the filter. The fiber optic coupling lens is disposed on the side of the isolator away from the beam splitter prism.

8. The tunable laser device according to claim 7, characterized in that, The beam splitter is formed by bonding two triangular beam splitters together with optical adhesive. The inclined surface of the beam splitter is configured to reflect a portion of the light to the optical power monitoring chip to achieve backlight monitoring. The remaining light is transmitted through the isolator and the fiber optic coupling lens and then enters the pigtail assembly.

9. The tunable laser device according to claim 1, characterized in that, The housing has a through hole, the fiber optic coupling lens is mounted in the through hole, and the housing has pins on its side.

10. An optical communication module, characterized in that, Including the tunable laser device as described in any one of claims 1 to 9.

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