Tail fiber vcsel laser module assembly package structure and method for reducing analog signal noise

Abstract

The application discloses a tail fiber VCSEL laser assembly packaging structure and method for reducing analog signal noise. The packaging structure is improved. The glass capillary is used to fix the optical fiber. The grinding angle of the end face of the optical fiber is not less than 11 degrees. A layer of anti-reflection film is coated on the grinding end face of the optical fiber and the grinding end face of the glass capillary, so that the reflected light of the grinding end face is reduced. The inner surface of the metal sleeve is roughened. Most of the light energy of the incident light cone emitted by the laser chip enters the optical fiber and the glass capillary through the grinding end face. A small part of the reflected light energy can only be kept in the reflected light cone and reflected to the outside of the coupling lens at a large reflection angle. The rough surface of the inner surface of the metal sleeve diffusely reflects the reflected light, greatly reduces the light signal jitter generated by the reflected light entering the laser chip, and the light signal jitter is less than 0.001. The packaging method is convenient for production. The grinding and coating errors can be greatly reduced during efficient batch production, and the quality control is facilitated.

Description

Technical Field

[0001] This invention relates to the field of analog optical signal semiconductor optoelectronic device technology, and in particular to a packaging structure, method and application of a VCSEL laser component with a pigtail for reducing analog signal noise. Background Technology

[0002] Driven by the continuous development of laser spectroscopy technology, the market demand for rapid measurement, high sensitivity, and miniaturized gas detection sensors is constantly increasing. VCSEL lasers, with their low power consumption, small size, low cost, strong near-infrared selectivity, wide tuning range with low current, and low electrothermal power, have become one of the ideal light sources for gas sensors. At room temperature, VCSEL lasers can emit 1.65-micron near-infrared laser light, making them an ideal light source for CH4 gas sensors.

[0003] Tunable Diode Laser Absorption Spectroscopy (TDLAS) is a common, highly sensitive gas detection method. Its working principle is based on the different characteristic absorption peaks of different gases. By appropriately selecting the wavelength of the characteristic absorption peak of the gas being measured and matching it with a laser source of the same wavelength, precise measurement of gas concentration can be achieved. When an infrared laser passes through the gas being measured, its intensity decreases due to the absorption effect of the characteristic absorption peak. The magnitude of this decrease is proportional to the concentration of the gas being measured and the optical path length of the beam through the gas. Therefore, when the optical path length is known, the concentration of the gas being measured can be detected by detecting and analyzing the change in intensity at the infrared absorption peak. When using TDLAS technology with a VCSEL laser as the sensor light source, the output wavelength of the VCSEL laser needs to be stabilized near the absorption peak of the gas (e.g., CH4) to facilitate concentration measurement. When using TDLAS technology, it is necessary to accurately measure the change in light intensity at the gas absorption peak, that is, the change in the light intensity signal of the absorption peak relative to the background noise signal. Therefore, it is necessary to minimize the error introduced by the change in the background noise signal.

[0004] Meanwhile, to accurately measure the concentration of CH4, especially low-concentration CH4 gas (the minimum measurement concentration required by national standards is 0.1% CH4), it is necessary to tune the output wavelength of the laser so that the scanning wavelength range can cover the CH4 gas absorption peak. To accurately determine the position of the CH4 gas absorption peak when measuring low-concentration CH4 gas, a reference gas cell containing a high concentration of CH4 gas is required. This necessitates splitting the laser source power using an optical fiber coupler and connecting it to the CH4 gas reference gas cell. As the laser environment changes, the laser wavelength will change. A gas sensor with a reference optical path can accurately locate the absorption wavelength and effectively prevent false alarms.

[0005] In a typical all-fiber gas sensing system, such as Figure 1 As shown, a VCSEL laser assembly 10 with an optical fiber pigtail is typically used as the light source. The laser beam can be split into three optical paths by two 1x2 optical fiber couplers 20. One path passes through the detection gas chamber 30 and is connected to the photodetector 50 to provide a reference signal; another path passes through the reference gas chamber 40 and is connected to the photodetector 60 to provide a detection signal; and the third path is connected to the photodetector 70 to provide a light source change monitoring signal.

[0006] When packaging conventional VCSEL laser assemblies with fiber optic pigtails for fiber optic communication, the fiber endface is typically ground at a 6° to 8° bevel to reduce the impact of reflected light. When these VCSEL laser assemblies are used in fiber optic communication applications, the transmitted communication signals are all digital signals of "0" or "1", and the requirement for low noise is not high, so these conventional pigtail-equipped VCSEL laser assemblies can be widely used. However, when these pigtail-equipped VCSEL laser assemblies are applied to high-precision sensors, the analog measurement of these sensors requires very low signal noise. Therefore, these pigtail-equipped VCSEL laser assemblies cannot be used in high-precision sensor applications that detect analog signals.

[0007] When measuring CH4 gas concentration with an accuracy of 0.1%, given the current typical detection length of 60mm for CH4 laser sensors, the signal jitter of the sensor light source itself must be less than 0.1%, i.e., jitter < 0.001. This requirement for low jitter in analog signals poses a challenge to the packaging process of VCSEL laser components with fiber optic pigtails.

[0008] Therefore, it is necessary to further develop a VCSEL laser assembly with a pigtail that reduces or avoids optical background noise caused by optical signal jitter in order to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0009] To address the inherent noise problem in existing fiber-coated VCSEL laser components, one objective of this invention is to provide a packaging structure for reducing analog signal noise. This structure utilizes a glass capillary instead of a conventional ceramic ferrule and employs a method of simultaneous grinding of the glass capillary and the optical fiber fixed within it. This ensures that the ground end face of the optical fiber and the ground end face of the glass capillary are ground at the same angle, with the radius of curvature (ROC) of the ground end face being ∞ and the grinding angle reaching 11.7°. This increases the angle between the center of the optical axis of the reflecting cone and the optical fiber axis to 23.4°. Meanwhile, an anti-reflection coating is deposited on the polished end face of the optical fiber and glass capillary. When the light cone emitted by the laser chip passes through the coupling lens to form an incident light cone, most of the light energy of the incident light cone enters the optical fiber and glass capillary through the polished end face coated with the anti-reflection coating. A small portion of the reflected light energy can only remain in the reflected light cone and is concentrated at a large reflection angle to be reflected outside the coupling lens. This prevents the light beam of the reflected light cone from returning to the laser chip through the coupling lens, thereby greatly reducing the intensity of the light reflected back to the laser chip. This minimizes the influence of the reflected light intensity generated by the light beam that does not participate in optical coupling, greatly reduces laser optical signal jitter, and lowers the laser's background noise.

[0010] The second objective of this invention is to provide a packaging method for a VCSEL laser with a pigtail packaging structure that reduces analog signal noise.

[0011] The third objective of this invention is to provide an application of a packaging structure for a VCSEL laser assembly with a pigtail that reduces analog signal noise.

[0012] One of the objectives of this invention is achieved through the following technical solution:

[0013] A fiber-coated VCSEL laser assembly packaging structure for reducing analog signal noise includes a metal sleeve and a coupling lens, a laser chip, an optical fiber, and a glass capillary tube disposed within the metal sleeve. At least one of the optical fibers is fixed within the glass capillary tube. The polishing angle of the polished end faces of the optical fiber and the glass capillary tube relative to the plane perpendicular to the optical fiber axis is not less than 11°, the radius of curvature (ROC) of the polished end faces of the optical fiber and the glass capillary tube is ∞, and the polishing angle of the polished end face of the glass capillary tube is consistent with the polishing angle of the polished end face of the optical fiber. Both the polished end faces of the optical fiber and the polished end faces of the glass capillary tube are coated with an anti-reflection film. The laser beam emitted by the laser chip is coupled through the coupling lens and enters the optical fiber and the glass capillary tube through the polished end faces of the optical fiber and the glass capillary tube coated with the anti-reflection film.

[0014] Furthermore, the grinding angle of the optical fiber grinding end face relative to the vertical plane of the optical fiber axis is 11.7°.

[0015] Furthermore, the polished end face of the optical fiber and the polished end face of the glass capillary are prepared by simultaneous polishing.

[0016] Furthermore, the antireflective coating is a C-band antireflective coating centered at a wavelength of 1650nm.

[0017] Furthermore, the antireflective coating is coated on both sides of the coupling lens.

[0018] Furthermore, the inner surface of the metal sleeve is a rough scattering surface.

[0019] The second objective of this invention is achieved through the following technical solution: a packaging method for a VCSEL laser component with a pigtail that reduces analog signal noise, as described above, comprising the following steps:

[0020] S1: Fix the optical fiber inside the glass capillary and perform synchronous grinding on the polished end face of the optical fiber and the polished end face of the glass capillary.

[0021] S2: After cleaning, the polished end face of the optical fiber and the polished end face of the glass capillary tube that have been synchronously polished in S1 are simultaneously coated with an anti-reflection film.

[0022] S3: Grind the inner surface of the metal sleeve to form a rough scattering surface;

[0023] S4: Install the VCSEL laser, the antireflective coupling lens, and the polished and antireflective fiber and glass capillary into the metal sleeve in S3, respectively.

[0024] Furthermore, in S1, the grinding angle between the polishing end face of the optical fiber and the polishing end face of the glass capillary is 11.7°.

[0025] The third objective of this invention is achieved through the following solution:

[0026] A VCSEL laser assembly with a fiber optic pigtail, the VCSEL laser assembly including the laser packaging structure described above; the VCSEL laser is used in a gas sensor, and the laser optical signal jitter is <0.001.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects:

[0028] 1. The VCSEL laser assembly packaging structure with a pigtail of the present invention replaces the conventional ceramic ferrule with a glass capillary tube. It employs a method of synchronous grinding of the glass capillary tube and the optical fiber fixed within it, ensuring that the grinding end face of the optical fiber and the grinding end face of the glass capillary tube are ground at the same grinding angle. The radius of curvature (ROC) of the optical fiber grinding end face is ∞, and the grinding angle of the optical fiber grinding end face reaches 11.7°. This increases the angle between the center of the optical axis of the reflected light cone and the optical fiber axis to 23.4°. When the light cone emitted by the laser chip passes through the coupling lens... The incident light cone is focused on the polished end face of the optical fiber and capillary. Most of the light energy of the incident light cone enters the optical fiber and glass capillary through the antireflection film on the polished end face. A small portion of the reflected light energy can only remain in the reflection light cone and is reflected out of the coupling lens at a large reflection angle. This prevents the light beam from the reflection light cone from returning to the laser chip through the coupling lens, thereby greatly reducing the intensity of the light reflected back to the laser chip. This minimizes the influence of the reflected light intensity generated by the light beam that does not participate in the optical coupling, greatly reduces the jitter of the laser optical signal, and lowers the laser's background noise.

[0029] 2. In addition, the present invention simultaneously deposits an antireflection film on the polished end face of the optical fiber and the polished end face of the glass capillary, further increasing the light energy entering the optical fiber and the glass capillary through the antireflection film, reducing the light intensity reflected back to the laser chip, and reducing laser optical signal jitter.

[0030] 3. In order to reduce the reflected light generated by the coupling lens and the inner surface of the metal sleeve at the same time, and to reduce the secondary reflection of the reflected light, the present invention further coats an anti-reflection film on both sides of the coupling lens and polishes the inner surface of the metal sleeve to form a rough scattering surface.

[0031] In summary, by improving the packaging structure, the laser chip emits a light cone that is coupled to form an incident light cone. Most of the light energy of the incident light cone enters the optical fiber and glass capillary through the antireflection film on the polished end face of the optical fiber and glass capillary. A small portion of the reflected light energy remains within the reflected light cone and is reflected out of the coupling lens at a large reflection angle. It is then diffusely reflected by the rough surface of the inner surface of the metal sleeve, which greatly reduces or almost eliminates the optical signal jitter caused by the reflected light entering the laser chip. The VCSEL laser using the packaging structure described in this invention has an optical signal jitter of <0.001, meaning that the laser has low background noise.

[0032] 4. By employing a method of synchronous grinding of a glass capillary and an optical fiber fixed within the glass capillary, this invention not only ensures that the grinding end face of the optical fiber and the grinding end face of the glass capillary are ground at the same grinding angle, but also enables batch grinding and batch antireflection coating, facilitating production. While achieving efficient batch production, it can also greatly reduce grinding and coating errors, which is beneficial for quality control. This further ensures that the optical signal jitter of the packaging structure of this invention meets the detection requirements of high-precision sensors. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a typical all-fiber gas sensing system.

[0034] Figure 2 This is a schematic diagram showing the grinding angle between the polished end face of the optical fiber and the polished end face of the glass capillary in the packaging structure of the VCSEL laser component with pigtail for reducing analog signal noise in Embodiments 1-3 of the present invention.

[0035] Figure 3 This is a schematic diagram of the beam cone state of the VCSEL laser component packaging structure with a pigtail for reducing analog signal noise in Embodiment 1 of the present invention;

[0036] Figure 4 This is a schematic diagram of the packaging state of the VCSEL laser assembly with pigtail for reducing analog signal noise according to Embodiments 1-3 of the present invention.

[0037] Figure 5 This is a schematic diagram of the radius of curvature of the packaging structure of the VCSEL laser component with a pigtail for reducing analog signal noise in Embodiments 2-3 of the present invention;

[0038] Figure 6 This is a schematic diagram of the laser optical signal jitter test results using the VCSEL laser assembly packaging structure with a pigtail according to Embodiment 1 of the present invention.

[0039] Figure 7 This is a schematic diagram of the laser optical signal jitter test results using the VCSEL laser assembly packaging structure with a pigtail according to Embodiment 2 of the present invention.

[0040] Figure 8 This is a schematic diagram of the laser optical signal jitter test results using the VCSEL laser assembly packaging structure with a pigtail according to Embodiment 3 of the present invention.

[0041] In the figure: 10, VCSEL laser assembly with pigtail; 20, fiber optic coupler; 30, gas detection chamber for the gas being measured; 40, reference chamber; 50, detector; 60, detector; 70, detector; 1, metal sleeve; 2, coupling lens; 3, laser chip; 4, optical fiber; 41, polished end face of optical fiber; 5, glass capillary; 51, polished end face of glass capillary; A1, light cone emitted by the laser chip; A2, incident light cone; A3, reflected light cone; B, optical fiber axis; ROC, radius of curvature; α, polishing angle between the polished end face of the optical fiber and the polished end face of the glass capillary. Detailed Implementation

[0042] To facilitate understanding of the present invention, the technical solutions and advantages of the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific structures and features of the present invention are illustrated by way of example and should not be construed as limiting the invention in any way. Furthermore, any of the technical features mentioned below (including implicit or disclosed features), as well as any technical features directly shown or implied in the figures, can be arbitrarily combined or deleted among these technical features to form other embodiments that may not be directly or indirectly mentioned in the present invention. The accompanying drawings show preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0043] In the description of this invention, unless otherwise stated, the terms "top", "bottom", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0044] Example 1

[0045] like Figure 2-4 , Figure 6As shown, a VCSEL laser assembly packaging structure with a pigtail for reducing analog signal noise is disclosed. The packaging structure includes a metal sleeve 1 and a coupling lens 2, a laser chip 3, an optical fiber 4, and a glass capillary 5 disposed within the metal sleeve 1. At least one of the optical fibers 4 is fixed within the glass capillary 5. The grinding angle α of the polished end face 41 of the optical fiber relative to the vertical plane of the optical fiber axis B is 11.7°, and the radius of curvature (ROC) of the polished end face of the optical fiber is ∞. The grinding angle α of the polished end face 51 of the glass capillary is the same as that of the polished end face 41 of the optical fiber. Both the polished end face 41 of the optical fiber and the polished end face 51 of the glass capillary are coated with an antireflection film (not shown in the figure). The laser beam emitted by the laser chip 3 is focused by the coupling lens 2 onto the polished end faces of the optical fiber 4 and the glass capillary 5, and enters the optical fiber 4 and the glass capillary 5 through the antireflection film on the polished end faces of the optical fiber 4 and the glass capillary 5.

[0046] In laser applications, when coupling the light source to an optical fiber, to reduce coupling loss, inject more optical power into the fiber, and achieve maximum coupling efficiency, the characteristics of the fiber and the light source, as well as the specific coupling method, must be considered. When a VCSEL laser beam is emitted, it forms a conical diverging beam. A coupling lens is needed to couple the laser beam to the fiber end face, generating a similar conical beam at the fiber end face. Based on the characteristics of the fiber, the geometry of the ideal coupling beam with maximum intensity is fixed. Therefore, to achieve ideal coupling efficiency, the incident beam's beam cone must coincide to the maximum extent with the ideal beam cone of the fiber. To prevent the incident beam's beam cone from reflecting back into the laser chip at the fiber end face, the angle of the fiber end face must be large enough so that the incident beam's beam cone, after reflection at the fiber end face, cannot pass through the lens and reach the laser chip. However, while increasing the angle of the fiber end face, the maximum angle of the incident beam must also be considered. If the angle of the fiber end face is too large and the maximum angle of the beam is also large, some light energy will not be coupled into the fiber, reducing the coupling efficiency. Therefore, the angle of the fiber end face is not necessarily better the larger it is.

[0047] Under the aforementioned premises, through continuous creative research and development, the applicant has achieved a grinding angle of over 11° between the polished fiber end face and the vertical plane of the fiber axis, while ensuring that the optical coupling efficiency and normal laser packaging are not affected. In this embodiment, the grinding angle between the polished fiber end face and the vertical plane of the fiber axis is 11.7°. This angle was selected by the applicant through continuous experimentation, adjustment, testing, and based on the results of optical signal jitter. In other embodiments, the grinding angle can also be selected from other angles, such as over 12° or less than 11.7°, as long as it can be combined with the radius of curvature (ROC) of the polished fiber end face and the glass capillary to achieve the beneficial effects of this invention, without affecting the optical coupling efficiency or laser packaging defects.

[0048] Furthermore, while increasing the grinding angle α of the fiber polishing end face relative to the fiber optical axis, the closer the fiber polishing end face 41 is to a plane, the better its effect of reducing light reflected back to the laser chip. In this embodiment, the radius of curvature (ROC) of the fiber polishing end face 41 is ∞, i.e., a plane.

[0049] Preferably, the optical fiber polishing end face 41 and the glass capillary polishing end face 51 are prepared by simultaneous polishing.

[0050] In this embodiment, the glass capillary tube 5 and the optical fiber 4 fixed inside the glass capillary tube 5 are polished simultaneously. This not only ensures that the polishing end face 41 of the optical fiber and the polishing end face 51 of the glass capillary tube are polished to the same polishing angle, and that the radius of curvature (ROC) of the polishing end face 41 of the optical fiber is ∞, but also facilitates mass production. Simultaneously, the polishing angle α of the optical fiber polishing end face 41 relative to the optical fiber axis B reaches 11.7°. This increases the angle between the center of the optical axis of the reflecting light cone A3 and the optical fiber axis B to 23.4°. When the light cone A1 emitted by the laser chip 3 is coupled... Lens 2 forms an incident light cone A2. By changing the reflection angle of the light reflected from the polished end face 41 of the optical fiber, most of the light energy of the incident light cone A2 enters the optical fiber 4 and the glass capillary 5. A small portion of the reflected light energy can only remain in the reflection light cone A3 and is concentrated at a large reflection angle to be reflected out of the coupling lens 2. This prevents the light beam of the reflection light cone A3 from returning to the laser chip 3 through the coupling lens 2, thereby greatly reducing the intensity of the light reflected back to the laser chip 3. This minimizes the influence of the reflected light intensity generated by the light beam that does not participate in the optical coupling, greatly reduces the jitter of the laser optical signal, and lowers the laser's background noise.

[0051] Preferably, the polished end face 41 of the optical fiber and the polished end face 51 of the glass capillary are respectively coated with an antireflection film (not shown in the figure). This invention simultaneously coats the polished end face 41 of the optical fiber and the polished end face 51 of the glass capillary with an antireflection film. Thus, when the laser is coupled to the polished end face of the optical fiber and the glass capillary, most of the light energy of the incident light cone passes through the antireflection film on the polished end face and enters the optical fiber and the glass capillary, further reducing the intensity of the light reflected back to the laser chip, reducing laser signal jitter, and lowering the laser's background noise.

[0052] Specifically, the antireflective coating is a C-band antireflective coating centered at a wavelength of 1650nm. In this embodiment, the antireflective coating is a C-band antireflective coating centered at a wavelength of 1650nm. Its material properties, light transmission enhancement principle, and coating technology are all based on existing technologies, as long as the beneficial effects can be achieved.

[0053] Preferably, the antireflective coating is coated on both sides of the coupling lens 2. This configuration can reduce the influence of reflected light from the two transmission surfaces of the coupling lens, thereby further reducing the intensity of light reflected back to the laser chip, reducing optical signal jitter, and lowering the laser's background noise.

[0054] To reduce the secondary reflection of the incident light cone A2 after reflection at the fiber polishing end face 41 by the inner surface of the metal sleeve 1, preferably, the inner surface of the metal sleeve 1 is a rough scattering surface. This design ensures that even if a small portion of the reflected light energy remains within the reflecting cone and is reflected outside the coupling lens, it is diffusely reflected by the rough surface of the metal sleeve, further reducing the disturbance caused by the reflected light entering the laser chip.

[0055] In summary, as Figure 6 As shown, by improving the packaging structure, the laser chip emits a light cone that forms an incident light cone through a coupling lens. Most of the light energy of the incident light cone enters the optical fiber and glass capillary through the antireflection film on the polished end face of the optical fiber and glass capillary. A small portion of the reflected light energy can only be kept in the reflected light cone and concentrated at a large reflection angle to be reflected outside the coupling lens. It is diffusely reflected by the rough surface of the inner surface of the metal sleeve, which greatly reduces or almost avoids the optical signal jitter caused by the reflected light entering the laser chip. The VCSEL laser assembly with a pigtail using the packaging structure of the present invention has an optical signal jitter of <0.001.

[0056] In this embodiment, the installation method, control method, working principle, and parameters of the laser chip 3, metal sleeve 1, and coupling lens 2 can all refer to existing technologies, and any method that can achieve its beneficial effects can be implemented. The optical fiber 4, glass capillary tube 5, laser chip 3, and coupling lens 2 are all suitable for the high-precision sensor application of this invention.

[0057] Optionally, the coupling lens 2 is a coaxial TO lens.

[0058] This embodiment 1 provides a packaging method for the above-described packaging structure, which includes the following steps:

[0059] S1: Fix the optical fiber inside the glass capillary tube, and perform synchronous grinding on the optical fiber grinding end face and the glass capillary grinding end face. After synchronous grinding, the grinding angle between the optical fiber grinding end face and the glass capillary grinding end face is 11.7°, and the radius of curvature (ROC) of the optical fiber grinding end face is ∞.

[0060] S2: After cleaning, the polished end face of the optical fiber and the polished end face of the glass capillary tube that have been synchronously polished in S1 are simultaneously coated with an anti-reflection film.

[0061] S3: Grind the inner surface of the metal sleeve to form a rough scattering surface;

[0062] S4: Install the VCSEL laser, the antireflective coupling lens, and the polished and antireflective fiber and glass capillary into the metal sleeve in S3, respectively.

[0063] In the encapsulation method of this embodiment, by using a glass capillary and an optical fiber fixed inside the glass capillary to grind simultaneously, not only can the grinding end face of the optical fiber and the grinding end face of the glass capillary be ground to the same grinding angle, but batch grinding and batch antireflection coating can also be achieved, which is convenient for production. While achieving efficient batch production, it can also greatly reduce grinding and coating errors, which is beneficial to quality control, thereby further ensuring that the optical signal jitter of the encapsulation structure of this invention meets the detection requirements of high-precision sensors.

[0064] Furthermore, in the encapsulation method of this embodiment, the synchronous polishing of the glass capillary and the optical fiber fixed inside the glass capillary specifically involves fixing the optical fiber and the glass capillary in a suitable fixture so that the end faces of the optical fiber and the glass capillary can be polished to the required angle simultaneously. The fixture, polishing device, and other relevant parameters required to achieve synchronous polishing can all be found in optical fiber polishing processes in the field, and will not be elaborated here.

[0065] This embodiment 1 also provides a VCSEL laser assembly with a pigtail, including the above-described laser assembly packaging structure.

[0066] Example 2

[0067] like Figure 2 , Figure 4-5 , Figure 7 As shown, the difference between this embodiment 2 and embodiment 1 is that the radius of curvature (ROC) of the polished fiber end face is 5≤ROC≤12mm.

[0068] The packaging method in this embodiment 2 is the same as that in embodiment 1.

[0069] This embodiment 2 also provides a VCSEL laser assembly with a pigtail, including the above-described laser assembly packaging structure.

[0070] Example 3

[0071] like Figure 2 , Figure 4-5 , Figure 8 As shown, the difference between this embodiment 3 and embodiment 1 is that the grinding angle of the optical fiber polishing end face relative to the vertical plane of the optical fiber axis is 8°, and the radius of curvature (ROC) of the optical fiber polishing end face is 5≤ROC≤12mm.

[0072] The packaging method in this embodiment 3 is the same as that in embodiment 1.

[0073] This embodiment 3 also provides a VCSEL laser assembly with a pigtail, including the laser packaging structure described above.

[0074] Effect evaluation and performance testing

[0075] The following are test data on laser signal jitter generated by the VCSEL laser assembly packaging structure with pigtail in Embodiments 1-3 of the present invention.

[0076] The laser jitter signal is detected using the following method:

[0077] Connect the VCSEL laser assembly 10 with a fiber optic pigtail to the gas detection system, such as... Figure 1 As shown, a VCSEL laser is driven by a periodically varying sawtooth wave current. If the reflected light from the polished end face of the optical fiber and glass capillary is reflected into the laser chip, interference noise will be generated in the output beam of the laser. This jitter noise signal can be directly detected by normalizing the signal from detector 7 and the sawtooth wave driving current.

[0078] The test results are shown in the table below. Figure 6-8 As shown:

[0079] item Example 1 Example 2 Example 3 Light source signal regression difference (jitter) ＜0.001 0.002 0.006

[0080] According to the data in the table above, Example 1 is the optimal embodiment of the present invention. The glass capillary and the optical fiber fixed within the glass capillary are simultaneously ground to 11.7° and coated with an anti-reflection film. The radius of curvature (ROC) of the ground fiber end face is ∞. Furthermore, an anti-reflection film is coated on both sides of the coupling lens, and the inner surface of the metal sleeve is polished to form a rough scattering surface. That is, the encapsulation structure of Example 1 not only improves the angle of the ground fiber end face but also uses a glass material similar to the optical fiber instead of a conventional ceramic ferrule. After grinding the end faces of the optical fiber and the glass capillary, an anti-reflection film is coated, allowing most of the light energy of the incident light cone to pass through the anti-reflection film on the ground end faces of the optical fiber and the glass capillary. Within the fiber and glass capillary, a small portion of the reflected light energy is contained within the reflective cone and concentrated at a relatively large reflection angle before being reflected out of the coupling lens. This prevents the light beam from returning to the laser chip via the coupling lens, significantly reducing the intensity of light reflected back to the laser chip. Furthermore, by reducing the reflected light generated by the coupling lens and the inner surface of the metal sleeve, secondary reflection of the reflected light is reduced. Therefore, the optical signal jitter caused by the reflected light entering the laser chip is greatly reduced or almost eliminated. The VCSEL laser assembly with a pigtail using the packaging structure of Example 1 has an optical signal jitter of <0.001, which meets the requirements of the gas sensor for measuring a 0.1% gas concentration in an existing detection chamber with a length of 60 mm.

[0081] The difference between Example 2 and Example 1 is that the radius of curvature (ROC) of the polished fiber end face is not ∞, i.e., it is a plane. Its radius of curvature (ROC) is 5≤ROC≤12mm. The VCSEL laser with pigtail using the packaging structure of Example 2 has an optical signal jitter of 0.002. This is because the fiber reflective surface is not a plane. Since part of the reflected light from the fiber end face enters the laser after multiple reflections, the intensity of the light reflected back to the laser chip is increased, which causes optical signal jitter.

[0082] The difference between Example 3 and Example 1 is that the grinding angle of the fiber polishing end face relative to the vertical plane of the fiber optical axis is 8°, and the radius of curvature (ROC) of the fiber polishing end face is 5≤ROC≤12mm. That is, the grinding angle of the fiber polishing end face relative to the vertical plane of the fiber optical axis is smaller than that of Example 1. At the same time, the fiber reflective surface is not a plane. Therefore, the smaller angle of the fiber polishing end face cannot prevent more light cones of the incident beam from being reflected back to the laser chip at the fiber end face. The light reflection loss is low. The part of the reflected light reflected by the fiber end face enters the laser after multiple reflections, thereby greatly enhancing the light intensity reflected back to the laser chip. The VCSEL laser assembly with pigtail using the packaging structure of Example 3 has an optical signal jitter of 0.006, which cannot meet the requirements of a high-precision gas sensor.

[0083] In summary, the VCSEL laser assembly packaging structure with a pigtail of the present invention replaces the conventional ceramic ferrule with a glass capillary tube. It employs a method of simultaneous grinding of the glass capillary tube and the optical fiber fixed within it, ensuring that the ground end face of the optical fiber and the ground end face of the glass capillary tube are ground at the same grinding angle. The radius of curvature (ROC) of the ground end face of the optical fiber is ∞, and the grinding angle of the optical fiber end face reaches 11.7°. This increases the angle between the center of the optical axis of the reflective cone and the optical axis of the optical fiber to 23.4°. Furthermore, the present invention coats an antireflection film on both the ground end face of the optical fiber and the ground end face of the glass capillary tube. When the laser... The light cone emitted by the laser chip is coupled through a coupling lens to form an incident light cone, which is then focused on the polished end face of the optical fiber and glass capillary. Most of the light energy of the incident light cone passes through the antireflection coating on the end face of the optical fiber and glass capillary and enters the optical fiber and glass capillary. A small portion of the reflected light energy can only remain in the reflected light cone and is reflected out of the coupling lens at a large reflection angle. This prevents the light beam of the reflected light cone from returning to the laser chip through the coupling lens, thereby greatly reducing the intensity of the light reflected back to the laser chip. This minimizes the influence of the reflected light intensity generated by the light beam that does not participate in the optical coupling, greatly reduces the jitter of the laser optical signal, and lowers the laser's background noise.

[0084] To simultaneously reduce reflected light generated by the coupling lens and the inner surface of the metal sleeve, and to reduce secondary reflection of the reflected light, the present invention further coats an anti-reflection film on each side of the coupling lens and polishes the inner surface of the metal sleeve to form a rough scattering surface.

[0085] This invention improves the packaging structure so that the light cone emitted by the laser chip forms an incident light cone through a coupling lens. Most of the light energy of the incident light cone enters the optical fiber and glass capillary through the anti-reflection film on the end face of the optical fiber and glass capillary. A small portion of the reflected light energy can only be kept in the reflected light cone and reflected out of the coupling lens at a large reflection angle. It is diffusely reflected by the rough surface of the inner surface of the metal sleeve, which greatly reduces or almost avoids the optical signal jitter caused by the reflected light entering the laser chip. The VCSEL laser assembly with a pigtail using the packaging structure of this invention has an optical signal jitter of <0.001 and low laser noise, which meets the requirements of gas sensors measuring 0.1% gas concentration with an existing detection chamber length of 60mm.

[0086] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the VCSEL laser component packaging structure of the present invention. Of course, without affecting the difficulty of laser packaging and the normal operation of the laser, the bevel angle of the fiber polishing end face can be increased as needed. For those skilled in the art, it will be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A packaging structure for a VCSEL laser assembly with a pigtail to reduce analog signal noise, the packaging structure comprising a metal sleeve and a coupling lens, a laser chip, an optical fiber, and a glass capillary disposed within the metal sleeve; at least one of the optical fibers is fixed within the glass capillary; characterized in that, The polishing angle of the optical fiber end face relative to the perpendicular plane of the optical fiber axis is 11.7°, and the angle of the center of the optical axis of the reflecting cone relative to the optical fiber axis B is 23.4°; the radius of curvature of the optical fiber end face is ∞; the optical fiber end face and the glass capillary end face are prepared by simultaneous polishing, and the polishing angle of the glass capillary end face is the same as that of the optical fiber end face; the optical fiber end face and the glass capillary end face are simultaneously coated with an antireflection film; the inner surface of the metal sleeve is a rough scattering surface; the laser beam emitted by the laser chip is coupled by the coupling lens and enters the optical fiber and the glass capillary through the antireflection film on the end faces of the optical fiber and the glass capillary.

2. The packaging structure for a VCSEL laser assembly with a pigtail for reducing analog signal noise as described in claim 1, characterized in that, The antireflective coating is a C-band antireflective coating centered at a wavelength of 1650nm.

3. The packaging structure for a VCSEL laser assembly with a fiber optic pigtail for reducing analog signal noise as described in claim 2, characterized in that, The coupling lens is coated with the anti-reflective film on both sides.

4. A packaging method for a VCSEL laser component packaging structure with a fiber-coupled pigtail for reducing analog signal noise as described in any one of claims 1-3, characterized in that, Includes the following steps: S1: Fix the optical fiber inside the glass capillary and perform synchronous grinding on the polished end face of the optical fiber and the polished end face of the glass capillary. S2: After cleaning, the polished end face of the optical fiber and the polished end face of the glass capillary tube that have been synchronously polished in S1 are simultaneously coated with an anti-reflection film. S3: Grind the inner surface of the metal sleeve to form a rough scattering surface; S4: Install the VCSEL laser, the antireflective coupling lens, the polished and antireflective fiber, and the glass capillary in the metal sleeve in S3.

5. The packaging method for a VCSEL laser component packaging structure with a fiber-coated pigtail for reducing analog signal noise as described in claim 4, characterized in that, In S1, the grinding angle between the polishing end face of the optical fiber and the polishing end face of the glass capillary is 11.7°.

6. A VCSEL laser assembly with a fiber optic pigtail, characterized in that, The VCSEL laser assembly with a pigtail includes the packaging structure of the VCSEL laser assembly with a pigtail as described in any one of claims 1-5; the VCSEL laser assembly with a pigtail is used in a gas sensor, and the laser light signal jitter is <0.001.

Images