Single-fiber three-transmitting and three-receiving optical device with hybrid packaging of double-transmitting TO and small-spacing TO

Abstract

The utility model discloses a double-transmitting TO and small-spacing TO mixed packaged single-fiber three-transmitting and three-receiving optical device, which comprises a double-transmitting TO packaging shell, a double-transmitting laser is arranged in the double-transmitting TO packaging shell, and a light combining assembly is arranged in the double-transmitting TO packaging shell; a 45-degree wave plate is arranged in front of a light outlet of a double-emission TO packaging shell, an independent emission laser is arranged on the lateral outer portion of the 45-degree wave plate, and a light splitting assembly, an insertion core end lens and an optical fiber adapter are arranged in front of the 45-degree wave plate. Light emitted by the two emitting lasers in the double-emitting laser is combined into one path of parallel light through the light combining assembly and then emitted out from a light outlet of the double-emitting TO packaging shell, and light emitted by the independent emitting laser is reflected by the 45-degree wave plate and then is parallel to the parallel light to form one path of collimated light beam. The collimated light beam passes through the light splitting assembly and the ferrule end lens and then is converged to the optical fiber adapter to form a main light path; the two paths of emitting lasers are integrated to the double-emission TO packaging shell, the two paths of emitting lasers and the external emitting lasers jointly form three emitters, the overall cost and size of an optical device are effectively considered, and the double-emission TO packaging shell is suitable for being used in a small space.

Description

Technical Field

[0001] The utility model relates to the technical field of optical communication, in particular to a single-fiber triple-transmission and triple-reception optical device with a hybrid package of dual-emission TO and small-spacing TO. Background Art

[0002] During the deployment of 50G PON, it is necessary to be compatible with the triple-mode transmission of three generations of PON (the three generations of PON are GPON, 10GPON, and 50GPON), that is, to simultaneously meet the transmission requirements of three different wavelengths for both the upstream and downstream. Existing traditional PON optical devices have only single-fiber single-transmission and dual-reception, single-fiber dual-transmission and single-reception, or single-fiber dual-transmission and dual-reception in the transmission channel, and cannot meet the triple-mode transmission requirements of 50G PON. Therefore, it is necessary to design a single-fiber triple-transmission and triple-reception optical device that can simultaneously meet the above transmission requirements.

[0003] In addition, with the market demand, optoelectronic products are required to have a certain cost performance. Although there are already individual integrated optical components with triple-transmission and triple-reception in the prior art, the types are very few. Not only is the internal structure complex, resulting in a relatively large product volume and high cost, but also the port density is low, which is not conducive to the marketization of products. Summary of the Utility Model

[0004] To solve the above problems, the utility model provides a single-fiber triple-transmission and triple-reception optical device with a hybrid package of dual-emission TO and small-spacing TO, which has a reasonable structure, effectively takes into account the overall cost and size of the optical device, and is suitable for use in a relatively small space.

[0005] The technical solution adopted by the utility model is as follows:

[0006] A single-fiber triple-transmission and triple-reception optical device with a hybrid package of dual-emission TO and small-spacing TO includes a dual-emission TO package housing. Inside the dual-emission TO package housing, dual-emission laser transmitters are installed in parallel. A light combining component is arranged inside the dual-emission TO package housing in front of the dual-emission laser transmitters. A 45° wave plate is arranged in front of the light outlet of the dual-emission TO package housing. An independent laser transmitter is arranged laterally outside the 45° wave plate. A beam splitting component, a ferrule end lens, and an optical fiber adapter are also arranged in front of the 45° wave plate. The light emitted by the two laser transmitters in the dual-emission laser transmitters is combined into a parallel light beam by the light combining component and emitted from the light outlet of the dual-emission TO package housing. The light emitted by the independent laser transmitter is reflected by the 45° wave plate and forms a collimated light beam in parallel with the parallel light beam. The collimated light beam passes through the beam splitting component and the ferrule end lens and then converges to the optical fiber adapter to form the main optical path.

[0007] As a further improvement of the above technical solution:

[0008] The beam splitting component includes a first filter disposed obliquely on the main optical path. Two wave plates are respectively arranged on both sides of the main optical path, including wave plate 1 and wave plate 3 on one side of the main optical path, and wave plate 2 and wave plate 4 on the other side of the main optical path. The light emitted from the fiber optic adapter is reflected by the first filter to wave plate 1. After being reflected by wave plate 1, one beam of light passes through wave plate 2 and is emitted to the first receiving detector, and the other beam of light is reflected by wave plate 1, wave plate 2, and wave plate 3 in sequence and then passes through wave plate 4 and is emitted to the second receiving detector. The first receiving detector and the second receiving detector are closely arranged on the same side of the main optical path.

[0009] The first filter is disposed obliquely relative to the main optical path at an angle less than 45°.

[0010] The first filter uses a wave plate with an inclination angle of 8° or 13°. The 8° wave plate is used for application scenarios with a wavelength interval less than 20 nm, and the 13° wave plate is used for application scenarios with a wavelength interval of 20 to 50 nm.

[0011] Wave plate 2 is a band-pass filter. The optical paths reflected by wave plate 1 and wave plate 3 are both emitted in a direction perpendicular to the main optical path. Wave plate 1, wave plate 2, and wave plate 3 are all disposed obliquely outside the main optical path, and wave plate 4 is disposed parallel to the main optical path outside.

[0012] A second filter is also disposed obliquely on the main optical path between the first filter and the fiber optic adapter. The light emitted from the fiber optic adapter is reflected by the second filter to wave plate 5, and after being reflected by wave plate 5, it is converted into an optical path perpendicular to the main optical path and emitted to the third receiving detector.

[0013] A wave plate 6 is disposed at the light incident end of the third receiving detector, and wave plate 6 is disposed parallel to the main optical path.

[0014] Wave plate 3 is a band-pass filter. The optical path reflected by wave plate 2 to wave plate 3 is split at wave plate 3. One beam of light passes through wave plate 3 and then enters the third receiving detector, and the other beam of light is reflected by wave plate 3 and then enters the second receiving detector.

[0015] Wave plate 1 is a band-pass filter. The optical path reflected by the first filter to wave plate 1 is split at wave plate 1. One beam of light passes through wave plate 1 and then enters the third receiving detector, and the other beam of light is reflected by wave plate 1 and then enters wave plate 2.

[0016] A lens 1 is evenly arranged between the two emission lasers in the dual-emission laser and the light combining component. An isolator is arranged on the main optical path between the 45° wave plate and the beam splitting component. The beam splitting component is accommodated in a metal housing, and the dual-emission TO package housing and the fiber optic adapter are assembled to the opposite ends of the metal housing by laser welding.

[0017] Compared with the prior art, the present utility model has the following beneficial effects:

[0018] By integrating two-way emission lasers into a dual-emission TO package housing and jointly forming a triple-emission with an external emission laser, the overall cost and size of the optical device are effectively balanced, making it suitable for use in a smaller space.

[0019] The present utility model also has the following advantages:

[0020] In the metal housing, the beam splitting component is composed of a wave plate combination, which not only effectively reduces the device cost, but also realizes a compression of more than 50% in the distance between the first receiving detector and the second receiving detector, greatly reducing the total length size of the optical device. It is suitable for 50G PON or other triple-emission and triple-reception optical device application fields that require a small-size space, facilitating the marketization of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the optical path diagram of the first embodiment of the present utility model.

[0022] Figure 2 It is the structural schematic diagram of the first embodiment of the present utility model.

[0023] Figure 3 It is the optical path diagram of the second embodiment of the present utility model.

[0024] Figure 4 It is the structural schematic diagram of the second embodiment of the present utility model.

[0025] Figure 5 It is the optical path diagram of the third embodiment of the present utility model.

[0026] Figure 6 It is the structural schematic diagram of the third embodiment of the present utility model.

[0027] Wherein: 1. Dual-emission TO package housing; 2. First filter; 3. Second filter; 4. First receiving detector; 5. Second receiving detector; 6. Third receiving detector; 7. Ferrule end lens; 8. Fiber adapter; 9. Independent emission laser;

[0028] 11. Dual-emission laser; 12. First lens; 13. Beam combining component;

[0029] 21. First wave plate; 22. Second wave plate; 23. Third wave plate; 24. Fourth wave plate;

[0030] 31. Fifth wave plate; 32. Sixth wave plate;

[0031] 91. 45° wave plate; 92. Isolator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following combines the drawings to illustrate the detailed embodiments of the present utility model.

[0033] As Figure 1 shown, a single-fiber triple-transmission and triple-reception optical device with hybrid packaging of dual-emission TO and small-pitch TO in this embodiment includes a dual-emission TO packaging housing 1. Inside the dual-emission TO packaging housing 1, dual-emission laser transmitters 11 are installed in parallel. A light combining component 13 is disposed in the dual-emission TO packaging housing 1 in front of the dual-emission laser transmitters 11; in front of the light outlet of the dual-emission TO packaging housing 1, a 45° wave plate 91 is arranged. An independent laser transmitter 9 is arranged laterally outside the 45° wave plate 91. In front of the 45° wave plate 91, a beam splitting component, a ferrule end lens 7, and an optical fiber adapter 8 are also arranged; the light emitted by the two laser transmitters in the dual-emission laser transmitters 11 is combined into a parallel light beam by the light combining component 13 and emitted from the light outlet of the dual-emission TO packaging housing 1. The light emitted by the independent laser transmitter 9 is reflected by the 45° wave plate 91 and forms a collimated light beam in parallel with the parallel light beam. The collimated light beam passes through the beam splitting component and the ferrule end lens 7 and then converges to the optical fiber adapter 8 to form the main optical path.

[0034] In this embodiment, by integrating two laser transmitters into the dual-emission TO packaging housing 1 and jointly forming triple emission with the external laser transmitter, the overall cost and size of the optical device are effectively balanced.

[0035] The beam splitting component includes a first filter 2 inclined on the main optical path. On both sides of the main optical path, two wave plates are respectively arranged, including a wave plate 21 and a wave plate 23 on one side of the main optical path, and a wave plate 22 and a wave plate 24 on the other side of the main optical path; the light emitted from the optical fiber adapter 8 is reflected by the first filter 2 to the wave plate 21. After being reflected by the wave plate 21, one beam of light passes through the wave plate 22 and is emitted to the first receiving detector 4, and the other beam of light is reflected by the wave plate 21, the wave plate 22, and the wave plate 23 in sequence and then passes through the wave plate 24 and is emitted to the second receiving detector 5; the first receiving detector 4 and the second receiving detector 5 are closely arranged on the same side of the main optical path.

[0036] In this embodiment, the beam splitting component is composed of a wave plate combination, which not only effectively reduces the device cost, but also enables the distance between the first receiving detector 4 and the second receiving detector 5 to be minimized by more than 50%, forming adjacent TOs with a small pitch. The overall layout structure is compact and reasonable; in actual operation, according to actual needs, the first receiving detector 4 and the second receiving detector 5 can also be packaged in the same TO package.

[0037] The first filter 2 is inclined relative to the main optical path at an angle less than 45°, so that the light emitted from the light adapter 8 can be laterally reflected by the first filter 2.

[0038] The first filter 2 uses a wave plate with an inclination angle (α) of 8° or a wave plate of 13°. The 8° wave plate is used for application scenarios with a wavelength interval of less than 20 nm, and the 13° wave plate is used for application scenarios with a wavelength interval of 20 to 50 nm.

[0039] In this embodiment, the actual angle of the first filter 2 can be determined in combination with the wavelength channel interval of the corresponding receiving end; the larger the angle of the first filter 2, the smaller the distance between the dual-transmitter TO package housing 1 and the adjacent first receiving detector 4, and the smaller the angle of the first filter 2, the larger the distance between the dual-transmitter TO package housing 1 and the adjacent first receiving detector 4.

[0040] The wave plate two 22 is a band-pass filter, and the optical paths reflected by the wave plate one 21 and the wave plate three 23 are both emitted in a direction perpendicular to the main optical path; the wave plate one 21, the wave plate two 22, and the wave plate three 23 are all inclined and arranged outside the main optical path, and the wave plate four 24 is arranged parallel to the main optical path outside; thus effectively ensuring that the optical paths reflected by the wave plate one 21 and the optical paths reflected by the wave plate three 23 can all be incident into the corresponding receiving detectors in a direction perpendicular to the main optical path.

[0041] Lenses one 12 are evenly arranged between the two emitting lasers in the dual-transmitter emitting laser 11 and the combining component 13, and an isolator 92 is arranged on the main optical path between the 45° wave plate 91 and the splitting component.

[0042] In this embodiment, the combining component 13 can be a PBS optical component or a Z-Block optical component.

[0043] PBS optical component is the abbreviation of Polarizing Beamsplitters. The PBS optical component in this embodiment includes three optical components corresponding to the three groups of laser emitters one by one. A single optical component is composed of two right-angled prisms glued together at the hypotenuse, and the inclined surfaces of the prisms are coated with a polarization splitting film.

[0044] The splitting component is accommodated in a metal housing, and the dual-transmitter TO package housing 1 and the fiber optic adapter 8 are assembled at opposite ends of the metal housing by laser welding.

[0045] In this embodiment, the independent emitting laser 9, the 45° wave plate 91, and the isolator 92 can all be accommodated in the metal housing.

[0046] In this embodiment, the splitting component in the metal housing is composed of a wave plate combination, which not only effectively reduces the device cost, but also realizes a compression of more than 50% in the distance between the first receiving detector 4 and the second receiving detector 5, greatly reducing the total length size of the optical device, and is applicable to 50G PON or other three-transmitter three-receiver optical device application fields that require small-size spaces, contributing to the marketization of the product.

[0047] In this embodiment, dual-channel TO and small-pitch TO are hybrid packaged. On the basis of reducing the device size, the port density is effectively increased by 50%, and the packaging process is simple.

[0048] Embodiment 1:

[0049] As Figure 1 and Figure 2 shown, a second filter 3 is also disposed obliquely on the main optical path between the first filter 2 and the fiber optic adapter 8. The light emitted from the fiber optic adapter 8 is reflected by the second filter 3 to the fifth wave plate 31, and is converted into an optical path perpendicular to the main optical path through the reflection of the fifth wave plate 31 and then emitted to the third receiving detector 6.

[0050] A sixth wave plate 32 is disposed at the light incident end of the third receiving detector 6, and the sixth wave plate 32 is disposed parallel to the main optical path.

[0051] In this embodiment, the optical path of the transmitting end is as follows: The light emitted by the two transmitting lasers in the dual-channel TO package housing 1 is collimated into parallel light by the first lens 12, and then the two parallel lights are combined into one parallel light by the light combining component 13 and emitted from the light outlet of the dual-channel TO package housing 1; at the same time, the light emitted by the independent transmitting laser 9 is reflected by the 45° wave plate 91 and then forms a collimated light beam in parallel with the above parallel light; the collimated light beam passes through the isolator 92, the first filter 2, the second filter 3, and the ferrule end lens 7 forward and then converges to the fiber optic adapter 8.

[0052] In this embodiment, the optical path of the receiving end is as follows: The converging light emitted from the fiber optic adapter 8 is collimated into parallel light through the ferrule end lens 7, is reflected by the second filter 3 to the fifth wave plate 31, and then passes through the sixth wave plate 32 and is incident into the third receiving detector 6; the light path passing through the second filter 3 is reflected by the first filter 2 to the first wave plate 21, and the light incident into the first receiving detector 4 after passing through the first wave plate 21 and then reflected by the second wave plate 22; the light reflected by the first wave plate 21 and then reflected by the second wave plate 22 and the third wave plate 23 in sequence passes through the fourth wave plate 24 and is incident into the second receiving detector 5.

[0053] Embodiment 2:

[0054] As Figure 3 and Figure 4 shown, the third wave plate 23 is a band-pass filter. The optical path reflected by the second wave plate 22 to the third wave plate 23 is split at the third wave plate 23. One path of light passes through the third wave plate 23 and is incident into the third receiving detector 6, and the other path of light is reflected by the third wave plate 23 and is incident into the second receiving detector 5.

[0055] In this embodiment, the optical path sequence at the transmitting end is as follows: The light emitted by the two emitting lasers in the dual-emitter TO package housing 1 is collimated into parallel light by the first lens 12, and then the two parallel light beams are combined into one parallel light beam by the light combining component 13 and emitted from the light outlet of the dual-emitter TO package housing 1. At the same time, the light emitted by the independent emitting laser 9 is reflected by the 45° wave plate 91 and then forms a collimated light beam in parallel with the above-mentioned parallel light. The collimated light beam passes through the isolator 92, the first filter 2, and the ferrule end lens 7 forward and then converges to the fiber optic adapter 8.

[0056] In this embodiment, the optical path sequence at the receiving end is as follows: The converging light emitted from the fiber optic adapter 8 is collimated into parallel light through the ferrule end lens 7, reflected by the first filter 2 to the first wave plate 21, and the light transmitted through the first wave plate 21 is incident on the first receiving detector 4, and the light reflected by the first wave plate 21 and then transmitted through the second wave plate 22 is incident on the third receiving detector 6, and the light reflected by the third wave plate 23 is incident on the second receiving detector 5 after passing through the fourth wave plate 24.

[0057] Embodiment 3:

[0058] As Figure 5 and Figure 6 shown, the first wave plate 21 is a band-pass filter, and the optical path reflected by the first filter 2 to the first wave plate 21 is split at the first wave plate 21. One path of light is transmitted through the first wave plate 21 and then incident on the third receiving detector 6, and the other path of light is reflected by the first wave plate 21 and then incident on the second wave plate 22.

[0059] In this embodiment, the optical path sequence at the transmitting end is as follows: The light emitted by the two emitting lasers in the dual-emitter TO package housing 1 is collimated into parallel light by the first lens 12, and then the two parallel light beams are combined into one parallel light beam by the light combining component 13 and emitted from the light outlet of the dual-emitter TO package housing 1. At the same time, the light emitted by the independent emitting laser 9 is reflected by the 45° wave plate 91 and then forms a collimated light beam in parallel with the above-mentioned parallel light. The collimated light beam passes through the isolator 92, the first filter 2, and the ferrule end lens 7 forward and then converges to the fiber optic adapter 8.

[0060] In this embodiment, the optical path sequence at the receiving end is as follows: The converging light emitted from the fiber optic adapter 8 is collimated into parallel light through the ferrule end lens 7, reflected by the first filter 2 to the first wave plate 21, the light transmitted through the first wave plate 21 is incident on the third receiving detector 6, the light reflected by the first wave plate 21 and then transmitted through the second wave plate 22 is incident on the first receiving detector 4, the light reflected by the first wave plate 21 and the second wave plate 22 in sequence is incident on the third wave plate 23, and the light reflected by the third wave plate 23 is incident on the second receiving detector 5 after passing through the fourth wave plate 24.

[0061] In this embodiment, TO package is the abbreviation of Transistor Outline package, which is a conventional transistor outline package.

[0062] By integrating two emission lasers into a dual-emission TO package housing, the utility model together with an external emission laser constitutes a triple-emission, effectively taking into account the overall cost and size of the optical device and being applicable to use in a relatively small space.

[0063] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference may be made to each other.

[0064] The above description is an explanation of the utility model, not a limitation thereof. For the scope defined by the utility model, reference may be made to the claims. Any form of modification may be made within the protection scope of the utility model.

Claims

1. A single-fiber three-transmitter and three-receiver optical device with a mixed package of double-transmitter TO and small-pitch TO, characterized by: The invention comprises a double-emission TO package shell (1), wherein double-emission lasers (11) are installed in parallel inside the double-emission TO package shell (1), and a light combining component (13) is arranged in the double-emission TO package shell (1) in front of the double-emission lasers (11); a 45° wave plate (91) is arranged in front of the light outlet of the double-emission TO package shell (1), an independent emitting laser (9) is arranged outside the lateral side of the 45° wave plate (91), and a light splitting component is also arranged in front of the 45° wave plate (91). , a core end lens (7), and an optical fiber adapter (8); the light emitted by the two emitting lasers in the dual-emitting emitting laser (11) is combined into a parallel light by a light combining component (13), and emitted from the light outlet of the dual-emitting TO package shell (1); the light emitted by the independent emitting laser (9) is reflected by a 45° wave plate (91) and is parallel to the parallel light to form a collimated light beam; the collimated light beam passes through the light splitting component and the core end lens (7) and then converges to the optical fiber adapter (8), forming a main light path.

2. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 1, characterized in that: The optical splitter assembly comprises a first filter (2) which is tiltedly located on a main optical path; two wave plates are arranged on both sides of the main optical path, including wave plate 1 (21) and wave plate 3 (23) located on one side of the main optical path, and wave plate 2 (22) and wave plate 4 (24) located on the other side of the main optical path; light emitted from the optical fiber adapter (8) is reflected to wave plate 1 (21) via the first filter (2); after being reflected by wave plate 1 (21), a beam of light is emitted to a first receiving detector (4) through wave plate 2 (22); and another beam of light is reflected by wave plate 1 (21), wave plate 2 (22), and wave plate 3 (23) in sequence, and then is emitted to a second receiving detector (5) through wave plate 4 (24); the first receiving detector (4) and the second receiving detector (5) are arranged adjacent to each other on the same side of the main optical path.

3. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 2, characterized in that: The first filter (2) is arranged obliquely at an angle less than 45° relative to the main light path.

4. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 3, characterized in that: The first filter (2) uses a wave plate with an inclination angle of 8° or a wave plate with an inclination angle of 13°. The 8° wave plate is used in application scenarios where the wavelength interval is less than 20 nm, and the 13° wave plate is used in application scenarios where the wavelength interval is 20 to 50 nm.

5. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 2, characterized in that: The wave plate 2 (22) is a bandpass filter, and the light paths after being reflected by the wave plate 1 (21) and the wave plate 3 (23) are all emitted in a direction perpendicular to the main light path; the wave plate 1 (21), the wave plate 2 (22), and the wave plate 3 (23) are all arranged obliquely outside the main light path, and the wave plate 4 (24) is arranged outside in parallel with the main light path.

6. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 2, characterized in that: A second filter (3) is also arranged obliquely on the main optical path between the first filter (2) and the optical fiber adapter (8); light emitted from the optical fiber adapter (8) is reflected by the second filter (3) to the wave plate five (31), and is transformed into a light path perpendicular to the main optical path by reflection from the wave plate five (31) and emitted to the third receiving detector (6).

7. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 6, characterized in that: The light input end of the third receiving detector (6) is provided with a wave plate six (32), and the wave plate six (32) is arranged parallel to the main light path.

8. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 2, characterized in that: The wave plate three (23) is a bandpass filter. The light path reflected from the wave plate two (22) to the wave plate three (23) is split at the wave plate three (23). One light path passes through the wave plate three (23) and is incident on the third receiving detector (6). The other light path is reflected from the wave plate three (23) and is incident on the second receiving detector (5).

9. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 2, characterized in that: The wave plate 1 (21) is a bandpass filter. The light path reflected from the first filter (2) to the wave plate 1 (21) is split at the wave plate 1 (21). One light path passes through the wave plate 1 (21) and is incident on the third receiving detector (6). The other light path is reflected from the wave plate 1 (21) and is incident on the wave plate 2 (22).

10. A single-fiber three-transmitter and three-receiver optical device with a double-transmitter TO and a small-pitch TO hybrid package as claimed in claim 1, characterized in that: Lenses 1 (12) are evenly arranged between the two emitting lasers in the dual-emitting laser (11) and the light combining component (13), and an isolator (92) is arranged on the main optical path between the 45° wave plate (91) and the light splitting component; the light splitting component is accommodated in a metal shell, and the dual-emitting TO package shell (1) and the optical fiber adapter (8) are assembled at opposite ends of the metal shell by laser welding.

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