Semiconductor laser chip and laser device

Abstract

The application discloses a semiconductor laser chip and a laser device, and relates to the technical field of semiconductors. The semiconductor laser chip provided by the embodiment of the application comprises an epitaxial wafer, a first film layer and a second film layer. The epitaxial wafer comprises a first quantum well structure, a tunnel junction and a second quantum well structure which are sequentially stacked along the fast axis direction of the semiconductor laser chip. The first film layer is formed on the front cavity surface of the epitaxial wafer, and the second film layer is formed on the rear cavity surface of the epitaxial wafer. The first film layer is used for forming a first light beam by transmitting photons generated by a first light emitting area and reflecting photons generated by a second light emitting area. The second film layer is used for forming a second light beam by transmitting photons generated by the second light emitting area and reflecting photons generated by the first light emitting area. The semiconductor laser chip provided by the application can effectively realize bidirectional light emission, improve the reliability of the semiconductor laser chip, and solve the problem of dark areas existing in the double-junction chip with unilateral light emission in the related art.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically, to a semiconductor laser chip and a laser device. Background Technology

[0002] In existing technologies, using tunnel junctions to cascade PN junctions (such as quantum well structures) in the vertical direction in multi-junction chips is an effective way to improve the output power of a single chip. Taking a dual-junction chip as an example, under ideal conditions, the output power of a dual-junction chip can reach about twice that of a single-junction chip, while also achieving effects such as single-sided dual-wavelength output, showing great application potential.

[0003] Currently, typical dual-junction chips have an antireflection (AR) coating on the front cavity surface and a high reflectance (HR) coating on the rear cavity surface, thus achieving unidirectional light emission from the front cavity surface. However, the presence of a dark area between the two output beams of a dual-junction chip leads to a decrease in brightness in the vertical direction, which is detrimental to fiber coupling applications. Furthermore, since two or more beams emerge from the same side, the distance between adjacent beams is relatively short, resulting in a higher front cavity surface temperature and poorer chip reliability. Utility Model Content

[0004] The purpose of this application is to provide a semiconductor laser chip and a laser device, wherein the semiconductor laser chip can meet high fiber coupling requirements and has good reliability.

[0005] The embodiments of this application can be implemented as follows:

[0006] In a first aspect, this application provides a semiconductor laser chip, including an epitaxial wafer, a first film layer, and a second film layer;

[0007] The epitaxial wafer includes a first light-emitting region and a second light-emitting region arranged along the fast axis direction of the semiconductor laser chip, a tunnel junction is arranged between the first light-emitting region and the second light-emitting region, and both the first light-emitting region and the second light-emitting region include a quantum well layer;

[0008] The first film layer is formed on the front cavity surface of the epitaxial wafer; the second film layer is formed on the rear cavity surface of the epitaxial wafer.

[0009] The first film layer is used to transmit photons generated by the first light-emitting region to form the first light beam and to reflect photons generated by the second light-emitting region.

[0010] The second film layer is used to transmit photons generated by the second light-emitting region to form a second light beam and to reflect photons generated by the first light-emitting region.

[0011] In an optional embodiment, the wavelength of the first beam is 650~1000nm, and the wavelength of the second beam is 800~1200nm.

[0012] In an optional embodiment, the reflectivity of the first film layer to the photons generated by the first light-emitting region is less than 5%, and the reflectivity of the second film layer to the photons generated by the second light-emitting region is less than 5%; the reflectivity of the first film layer to the photons generated by the second light-emitting region is not less than 95%, and the reflectivity of the second film layer to the photons generated by the first light-emitting region is not less than 95%.

[0013] In an optional embodiment, the light-emitting region includes an active layer disposed along the fast axis direction of the semiconductor laser chip, and confinement layers are disposed on both the upper and lower sides of the active layer; the refractive index of the confinement layers is less than that of the active layer; the light-emitting region includes a first light-emitting region and a second light-emitting region.

[0014] In an optional implementation, the active layer includes an N-type waveguide layer, a quantum well layer, and a P-type waveguide layer stacked sequentially.

[0015] In an optional implementation, the confinement layer, the N-type waveguide layer, and the P-type waveguide layer are made of AlGaAs, and the quantum well layer is made of GaAsP, InGaAs, or InAlGaAs.

[0016] In an optional implementation, the thickness of the quantum well layer in the fast axis direction of the semiconductor laser chip is 3~30nm.

[0017] In an optional embodiment, the active layer of the first light-emitting region includes a first quantum well layer; the active layer of the second light-emitting region includes a second quantum well layer; the first quantum well layer is a compressive strain quantum well or a tensile strain quantum well; the second quantum well layer is a compressive strain quantum well or a tensile strain quantum well; at least one of the first quantum well layer and the second quantum well layer is a tensile strain quantum well; and / or, at least one of the first quantum well layer and the second quantum well layer is a compressive strain quantum well.

[0018] In an optional implementation, the tunnel junction is made of GaAs.

[0019] In an optional implementation, the thickness of the tunnel junction in the fast axis direction of the semiconductor laser chip is 20~200nm.

[0020] In an optional embodiment, the first film layer includes an overlapping first sub-film layer and a second sub-film layer, the difference between the refractive indices of the first sub-film layer and the second sub-film layer is greater than or equal to 0.25, and the peak electric field intensity in the first film layer is not at the interface between the first sub-film layer and the second sub-film layer; and / or, the second film layer includes an overlapping first sub-film layer and a second sub-film layer, the difference between the refractive indices of the first sub-film layer and the second sub-film layer is greater than or equal to 0.25, and the peak electric field intensity in the second film layer is not at the interface between the first sub-film layer and the second sub-film layer.

[0021] In a second aspect, this application provides a laser device comprising a semiconductor laser chip according to any of the embodiments of the first aspect above, or a semiconductor laser chip manufactured by a method comprising any of the embodiments of the second aspect above.

[0022] In an optional embodiment, the laser device includes a plurality of semiconductor laser chips and an optical path coupling component. The optical path coupling component is used to combine the first beams emitted by each semiconductor laser chip into a first converging beam, combine the second beams emitted by each semiconductor laser chip into a second converging beam, and combine the first converging beam and the second converging beam into a total output beam.

[0023] The beneficial effects of the embodiments of this application include:

[0024] The semiconductor laser chip provided in this application includes an epitaxial wafer, a first film layer, and a second film layer. The epitaxial wafer includes a first light-emitting region and a second light-emitting region disposed along the fast axis direction of the semiconductor laser chip. A tunnel junction is disposed between the first light-emitting region and the second light-emitting region. Both the first light-emitting region and the second light-emitting region include a quantum well structure. The first film layer is formed on the front cavity surface of the epitaxial wafer; the second film layer is formed on the rear cavity surface of the epitaxial wafer. The first film layer is used to transmit photons generated by the first light-emitting region to form a first light beam and to reflect photons generated by the second light-emitting region; the second film layer is used to transmit photons generated by the second light-emitting region to form a second light beam and to reflect photons generated by the first light-emitting region. By disposing the first film layer and the second film layer on cavity surfaces with different orientations, the semiconductor laser chip provided in this application can effectively achieve bidirectional light emission, thus reducing the thermal load on a single-sided cavity surface and improving the reliability of the semiconductor laser chip, making its reliability similar to that of a single-junction chip. Furthermore, since it emits light bidirectionally, it avoids the problem of dark areas between adjacent light spots that exist in unidirectional light emission, and solves the problem of difficulty in application due to dark areas between two light spots in unidirectional light emission. It also increases the adjustment space of the dual-junction spacing and improves the production tolerance and ease of use of semiconductor laser chips.

[0025] The method for manufacturing a semiconductor laser chip provided in this application is used to manufacture the aforementioned semiconductor laser chip; the laser device provided in this application includes the aforementioned semiconductor laser chip, and therefore has better reliability. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of a semiconductor laser chip in related technologies;

[0028] Figure 2 This is a schematic diagram of a semiconductor laser chip in one embodiment of this application;

[0029] Figure 3 This is a schematic diagram showing the arrangement of multiple semiconductor laser chips in a laser device according to one embodiment of this application.

[0030] Icons: 100 - Semiconductor laser chip; 101 - Antireflective coating; 102 - High reflectivity coating; 110 - First light-emitting region; 111 - First confinement layer; 112 - First active layer; 1121 - First N-type waveguide layer; 1122 - First quantum well layer; 1123 - First P-type waveguide layer; 113 - Second confinement layer; 120 - Second light-emitting region; 121 - Third confinement layer; 122 - Second active layer; 1221 - Second N-type waveguide layer; 1222 - Second quantum well layer; 1223 - Second P-type waveguide layer; 123 - Fourth confinement layer; 130 - Tunnel junction; 131 - N-type sublayer; 132 - P-type sublayer; 140 - First film layer; 150 - Second film layer; 160 - Cap layer; 170 - Substrate; 180 - Buffer layer; 210 - First optical device; 220 - Second optical device; 230 - Third optical device; 240 - Fourth optical device; 310 - First collector beam; 320 - Second collector beam; 400 - Total output beam. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0033] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] In the description of this application, it should be noted that the use of terms such as "upper," "lower," "inner," and "outer" to indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the utility model product is in use, is merely for the convenience of describing this application and simplifying the description, and does 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 on this application. Furthermore, the use of terms such as "first" and "second" is merely for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0035] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0036] In related technologies, dual-junction or multi-junction chips emit light from the front cavity surface, which is unidirectional light emission. This can easily lead to higher temperatures on the cavity surface, placing high demands on its reliability. Figure 1 This is a schematic diagram of the structure of a semiconductor laser chip 100 in related technologies. (Example) Figure 1 As shown, the semiconductor laser chip 100 in the related technology includes a first light-emitting region 110, a tunnel junction 130, and a second light-emitting region 120 stacked sequentially. Both the first light-emitting region 110 and the second light-emitting region 120 have quantum well layers. The front cavity surface of the semiconductor laser chip 100 is coated with an anti-reflection film 101, and the rear cavity surface is coated with a high-reflection film 102. The light emission directions of the first light-emitting region 110 and the second light-emitting region 120 are consistent, achieving unidirectional light emission from the front cavity surface. The junction spacing L of the dual-junction chip (i.e., the distance between the quantum well layers of two adjacent light-emitting regions) is a key factor limiting its effective application. Because there is a dark area between the two output beams of the dual-junction chip, the brightness in the vertical direction decreases, which is not conducive to fiber coupling applications. In practical applications, the spacing between the two junctions is difficult to reduce because the adjacent light-emitting regions are separated by a tunnel junction 130 (TJ). Since the tunnel junction 130 is a highly doped region, a very low light field intensity distribution is required at this location. However, there is an upper limit to controlling the light emission distribution by adjusting the refractive index distribution using materials, making it difficult to achieve a junction spacing of less than 2 μm. Furthermore, a small junction spacing increases the thermal impact between the two light-emitting regions, leading to a decrease in the laser chip's output power. Simultaneously, the closer proximity of the light spots concentrates heat, reducing the laser chip's reliability. A typical dual-junction chip has a high optical power density at the antireflection coating 101 end and a high carrier density at the high-reflection coating 102 end. Influenced by spatial hole burning and two-photon absorption effects, the output power is lower than ideal. Therefore, typical dual-junction chips cannot achieve twice the output power, and reliability is difficult to guarantee. Based on this, the distance between the two junctions in a typical dual-junction chip is usually 4–7 μm, mainly used in scenarios with low coupling requirements (such as free space) and low thermal impact (such as pulsed conditions).

[0037] In order to improve the problem that the reliability of dual-junction (or multi-junction) semiconductor laser chips 100 in related technologies is low and it is difficult to meet the application scenarios with high coupling requirements, this application provides a semiconductor laser chip 100 that solves the problem of high single-sided cavity surface heat load and poor reliability caused by single-sided light output by bidirectional light output, and also improves the problem that dual-junction (or multi-junction) semiconductor laser chips 100 are difficult to apply due to dark areas.

[0038] Figure 2 This is a schematic diagram of a semiconductor laser chip 100 in one embodiment of this application. Figure 2 As shown, the semiconductor laser chip 100 provided in this embodiment includes an epitaxial wafer, a first film layer 140, and a second film layer 150. The epitaxial wafer includes a first light-emitting region 110, a tunnel junction 130, and a second light-emitting region 120 sequentially stacked along the fast axis of the semiconductor laser chip 100. Both the first light-emitting region 110 and the second light-emitting region 120 include quantum well structures capable of generating photons. The first film layer 140 is formed on the front cavity surface of the epitaxial wafer, and the second film layer 150 is formed on the rear cavity surface of the epitaxial wafer. The first film layer 140 transmits photons generated by the first light-emitting region 110 to form a first light beam and reflects photons generated by the second light-emitting region 120; the second film layer 150 transmits photons generated by the second light-emitting region 120 to form a second light beam and reflects photons generated by the first light-emitting region 110.

[0039] In this embodiment, the first direction facing the front cavity surface and the second direction facing the rear cavity surface are two opposite directions and both are perpendicular to the fast axis direction of the semiconductor laser chip 100.

[0040] Because the first film layer 140 can transmit photons generated by the first light-emitting region 110 and reflect photons generated by the second light-emitting region 120, photons generated by the first light-emitting region 110 can be emitted from the first film layer 140 to form a first beam of light propagating along the first direction. Photons emitted by the second light-emitting region 120, however, are reflected by the first film layer 140 and are difficult to emit from it, thus unable to propagate along the first direction. Similarly, the second film layer 150 can transmit photons generated by the second light-emitting region 120 and reflect photons generated by the first light-emitting region 110. Therefore, photons generated by the second light-emitting region 120 can be emitted from the second film layer 150 and propagate along the second direction. Photons generated by the first light-emitting region 110, however, are reflected by the second film layer 150 and are difficult to emit from it, thus unable to propagate along the second direction. Therefore, by setting the first film layer 140 and the second film layer 150, the semiconductor laser chip 100 emits a first beam of light along the first direction and a second beam of light along the second direction, thus achieving bidirectional light emission. Optionally, the wavelength of the first beam is different from the wavelength of the second beam.

[0041] In this embodiment, the first light-emitting region 110 includes a first confinement layer 111, a first active layer 112, and a second confinement layer 113, which are sequentially stacked along the fast axis direction of the semiconductor laser chip 100. The second light-emitting region 120 includes a third confinement layer 121, a second active layer 122, and a fourth confinement layer 123, which are sequentially stacked along the fast axis direction of the semiconductor laser chip 100. The first active layer 112 and the second active layer 122 have smaller bandgap widths, while the first confinement layer 111, the second confinement layer 113, the third confinement layer 121, and the fourth confinement layer 123 have larger bandgap widths. The refractive indices of the first confinement layer 111 and the second confinement layer 113 are both lower than the refractive index of the first active layer 112, making it difficult for light emitted from the first active layer 112 to easily enter other layers along the fast axis direction. Similarly, the refractive indices of the third confinement layer 121 and the fourth confinement layer 123 are both less than the refractive index of the second active layer 122, making it difficult for light emitted from the second active layer 122 to enter other layers along the fast axis.

[0042] In this embodiment, the first active layer 112 includes a first N-type waveguide layer 1121, a first quantum well layer 1122, and a first P-type waveguide layer 1123 stacked sequentially; the second active layer 122 includes a second N-type waveguide layer 1221, a second quantum well layer 1222, and a second P-type waveguide layer 1223 stacked sequentially. Optionally, the first N-type waveguide layer 1121 and the second N-type waveguide layer 1221 are made of N-type doped AlGaAs, and the first P-type waveguide layer 1123 and the second P-type waveguide layer 1223 are made of P-type doped AlGaAs. A quantum well structure is a structure formed by embedding one semiconductor material (well material) into another semiconductor material (barrier material). The key function of a quantum well structure is that it can confine charge carriers (electrons and holes) within a two-dimensional space, thereby forming the so-called "quantum confinement effect." The band gap of the well material is relatively small, while the band gap of the barrier material is relatively large. When electrons and holes move in a high-energy band material (trap material), they are confined by the band difference when they enter a low-energy band material (barrier material), thus forming a two-dimensional bound state of electrons and holes.

[0043] Optionally, the first confinement layer 111, the second confinement layer 113, the first N-type waveguide layer 1121, and the first P-type waveguide layer 1123 are made of AlGaAs, and the first quantum well layer 1122 is made of GaAsP, InGaAs, or InAlGaAs. The third confinement layer 121, the fourth confinement layer 123, the second N-type waveguide layer 1221, and the second P-type waveguide layer 1223 are made of AlGaAs, and the second quantum well layer 1222 is made of GaAsP, InGaAs, or InAlGaAs. For example, in an optional embodiment, the first confinement layer 111, the second confinement layer 113, the third confinement layer 121, and the fourth confinement layer 123 are all made of AlGaAs, and the first quantum well layer 1122 and the second quantum well layer 1222 are all made of GaAsP or all of them are InAlGaAs. Alternatively, the material of the first quantum well layer 1122 is either GaAsP or InAlGaAs, and the material of the second quantum well layer 1222 is either GaAsP or InAlGaAs.

[0044] Optionally, the materials of the first confinement layer 111, the second confinement layer 113, the third confinement layer 121, and the fourth confinement layer 123 are all doped AlGaAs. Specifically, the first confinement layer 111 and the third confinement layer 121 are P-type doped and are adjacent to the first P-type waveguide layer 1123 and the second P-type waveguide layer 1223, respectively; the second confinement layer 113 and the fourth confinement layer 123 are N-type doped and are adjacent to the first N-type waveguide layer 1121 and the second N-type waveguide layer 1221, respectively.

[0045] GaAsP possesses a direct bandgap structure, meaning that electrons can directly release photons when transitioning from the valence band to the conduction band. This characteristic gives GaAsP excellent light-emitting properties. Depending on the specific composition ratio of GaAsP, its bandgap width can be adjusted within a certain range, thus covering different wavelengths from red to orange to yellow. For example, a higher proportion of Ga and P in GaAsP results in a wider bandgap and a more greenish hue in the emitted light; conversely, a higher proportion of Ga and As results in a narrower bandgap and a more reddish hue in the emitted light. GaAsP materials exhibit good mechanical strength and high thermal stability, making them suitable for operation in high-temperature environments.

[0046] InGaAs, an important III-V compound semiconductor material, possesses characteristics such as tunable bandgap and high electron mobility. By adjusting the ratio of In to Ga, effective control of light wavelength can be achieved; for example, as the In content increases, the bandgap width decreases. InGaAs materials exhibit good material quality and are suitable for the 900–1000 nm wavelength range.

[0047] InAlGaAs, an important III-V compound semiconductor material, possesses characteristics such as tunable bandgap and high electron mobility. By adjusting the ratio of In, Al, and Ga, effective control of light wavelength can be achieved; for example, as the In content increases, the bandgap width decreases, while as the Al content increases, the bandgap width increases. Therefore, InAlGaAs can cover different wavelength ranges from near-infrared to visible light.

[0048] In this embodiment, since photons generated by the first quantum well layer 1122 can enter the first N-type waveguide layer 1121 and the first P-type waveguide layer 1123, and photons generated by the second quantum well layer 1222 can enter the second N-type waveguide layer 1221 and the second P-type waveguide layer 1223, each waveguide layer can expand the light generated by the quantum well layer, avoiding excessive concentration of light intensity. At the same time, the low AI composition design of the waveguide layer makes the refractive index of the waveguide layer higher than that of the confinement layer, thereby realizing the confinement of the light field by the confinement layer. Specifically, the second confinement layer 113 and the third confinement layer 121 can prevent light from the first active layer 112 and the second active layer 122 from entering the tunnel junction 130, reducing the optical loss of the tunnel junction 130; they also prevent the light of different wavelengths generated by the first active layer 112 and the second active layer 122 from interfering with each other, and prevent the second quantum well layer 1222 (or the first quantum well layer 1122) from being affected by the light beam emitted by the first quantum well layer 1122 (or the second quantum well layer 1222) and emitting a light beam of the same wavelength as the first quantum well layer 1122 (or the second quantum well layer 1222), thus ensuring that the first quantum well layer 1122 and the second quantum well layer 1222 can achieve dual-wavelength lasing. The first confinement layer 111 and the fourth confinement layer 123 can respectively block the photons emitted by the first active layer 112 and the second active layer 122, thereby reducing optical loss.

[0049] In this embodiment, the thickness of the first quantum well layer 1122 in the fast axis direction of the semiconductor laser chip 100 is 3~30nm, and can be further selected as 4~18nm; the thickness of the second quantum well layer 1222 in the fast axis direction of the semiconductor laser chip 100 is 3~30nm, and can be further selected as 4~18nm.

[0050] In one embodiment, the first quantum well layer 1122 is a compressive strain quantum well or a tensile strain quantum well; the second quantum well layer 1222 is a compressive strain quantum well or a tensile strain quantum well; at least one of the first quantum well layer 1122 and the second quantum well layer 1222 is a tensile strain quantum well; and / or, at least one of the first quantum well layer 1122 and the second quantum well layer 1222 is a compressive strain quantum well.

[0051] Optionally, the first quantum well layer 1122 is a tensile strain quantum well, and the second quantum well layer 1222 is also a tensile strain quantum well; or, the first quantum well layer 1122 is a compressive strain quantum well, and the second quantum well layer 1222 is a tensile strain quantum well; or, the first quantum well layer 1122 is a tensile strain quantum well, and the second quantum well layer 1222 is a compressive strain quantum well; or, the first quantum well layer 1122 is a compressive strain quantum well, and the second quantum well layer 1222 is also a compressive strain quantum well. In semiconductor laser chips, strain modulation of the quantum well region has a significant impact on the polarization characteristics of the device. Typically, compressive strain quantum well structures lower the gain threshold of the TM mode, making the device more inclined to support TE mode (transverse electric mode) lasing; while tensile strain quantum wells, on the contrary, are beneficial for the realization of the TM mode (transverse magnetic mode).

[0052] For short-wavelength laser chips, the use of tensile strain quantum well structure can achieve better material quality. This is mainly because tensile strain can effectively alleviate the defect density caused by lattice mismatch, thereby improving the crystal quality of the material. Preferably, the first quantum well layer 1122 is a tensile strain quantum well, and the second quantum well layer 1222 is also a tensile strain quantum well.

[0053] For long-wavelength laser chips, using compressive strain quantum wells is more conducive to obtaining high-quality materials. Compressive strain reduces the formation of non-radiative recombination centers by adjusting the valence band structure, thereby improving device performance. The first quantum well layer 1122 is preferably a compressive strain quantum well, and the second quantum well layer 1222 is also a compressive strain quantum well.

[0054] In other optional embodiments, the first light-emitting region 110 and the second light-emitting region 120 may also adopt other structures, such as a multi-quantum-well structure.

[0055] The tunnel junction 130 is used to achieve efficient transport of charge carriers (electrons and holes) between different quantum well structures. In this embodiment, the material of the tunnel junction 130 is GaAs. By controlling the thickness and doping of the GaAs layer, efficient tunneling can be achieved. In this embodiment, the thickness of the tunnel junction 130 in the fast axis direction of the semiconductor laser chip 100 is 20~200nm. If the tunnel junction 130 is too thick, the tunneling probability will be greatly reduced; if it is too thin, it may lead to excessive tunneling current, affecting the stability of the device. Specifically, the tunnel junction 130 includes a stacked N-type sublayer 131 and a P-type sublayer 132, wherein the N-type sublayer 131 is adjacent to the N-type doped second confinement layer 113, and the P-type sublayer 132 is adjacent to the P-type doped third confinement layer 121.

[0056] In this embodiment, the semiconductor laser chip 100 further includes a substrate 170 and a buffer layer 180, with the buffer layer 180 disposed between the substrate 170 and the fourth confinement layer 123. The materials of the substrate 170 and the buffer layer 180 may be GaAs. Optionally, the substrate 170 is an N-type doped substrate.

[0057] In this embodiment, the epitaxial wafer further includes a cap layer 160, which is disposed on the side of the first confinement layer 111 opposite to the first active layer 112. The cap layer 160 is used to form a good ohmic contact. Optionally, the cap layer 160 is a p-type doped cap layer.

[0058] In optional embodiments, the wavelength of the first beam is 650-1000 nm, and the wavelength of the second beam is 800-1200 nm, with the wavelength of the first beam being shorter than that of the second beam. In a specific embodiment, the wavelength of the first beam is 915 nm, and the wavelength of the second beam is 976 nm. The first film layer 140 is capable of transmitting the first beam with a wavelength of 915 nm and reflecting the second beam with a wavelength of 976 nm; the second film layer 150 is capable of reflecting the first beam with a wavelength of 915 nm and transmitting the second beam with a wavelength of 976 nm. It should be understood that in this embodiment, the first film layer 140 does not need to completely transmit the first beam or completely reflect the second beam; it is sufficient that it transmits most (more than 50%) of the first beam and reflects most (more than 50%) of the second beam. Similarly, the second film layer 150 does not need to completely transmit the second beam or completely reflect the first beam; it is sufficient that it transmits most (more than 50%) of the light to form the second beam and reflects most (more than 50%) of the light to form the first beam.

[0059] Optionally, the reflectivity of the first film layer 140 to the photons generated by the first light-emitting region 110 is less than 5%, and the reflectivity of the second film layer 150 to the photons generated by the second light-emitting region 120 is less than 5%; alternatively, the reflectivity of the first film layer 140 to the photons generated by the first light-emitting region 110 is less than 5%, and the reflectivity of the second film layer to the photons generated by the second light-emitting region 120 is less than 5%; the reflectivity of the first film layer to the photons generated by the second light-emitting region is not less than 95%, and the reflectivity of the second film layer to the photons generated by the first light-emitting region is not less than 95%.

[0060] In this embodiment, the first film layer 140 has a reflectivity of 3.8% for a 915nm light beam and a reflectivity of 99% for a 976nm light beam; the second film layer 150 has a reflectivity of 96.5% for a 915nm light beam and a reflectivity of 2.5% for a 976nm light beam.

[0061] The first film layer includes alternating layers of first and second sub-film layers, with at least one first and one second sub-film layer, and the difference between the refractive index of the first and second sub-film layers is greater than or equal to 0.25. One first sub-film layer and one second sub-film layer constitute a pair, forming a double film structure. The number of double film structures is inversely correlated with the refractive index difference corresponding to the double film structure. The greater the difference between the refractive index of the first and second sub-film layers in the double film structure, the fewer the number of double film structures.

[0062] In an optional embodiment, the peak electric field intensity in the first film layer is not located at the interface between the first sub-film layer and the second sub-film layer; and / or, the peak electric field intensity in the second film layer is not located at the interface between the first sub-film layer and the second sub-film layer. The interface between the first sub-film layer and the second sub-film layer is relatively weak. If the peak electric field intensity is located at the interface between the first sub-film layer and the second sub-film layer (or at the contact point between the first sub-film layer and the second sub-film layer), it will adversely affect the quality of the first sub-film layer and the second sub-film layer, thereby leading to device failure. Therefore, this application has specially designed the first film layer and the second film layer so that there is no peak electric field intensity at the interface between the first sub-film layer and the second sub-film layer.

[0063] Optionally, a quarter-wavelength thickness system can be used for sub-layer thickness design, where each sub-layer satisfies d = λ / 4n, where d is the sub-layer thickness, λ is the wavelength of the light to be reflected, and n is the refractive index of the sub-layer. By controlling the refractive index and thickness of the sub-layers, the peak electric field intensity can be prevented from occurring at the boundaries between the sub-layers. As can be seen from the formula d = λ / 4n, the larger n is, the smaller the thickness d is. If the refractive index of the high-refractive-index film is n... H The refractive index of the low refractive index film is n L Let p represent the number of double-layer structures. In the case of a layer arrangement of substrate | high-refractive-index layer | low-refractive-index layer ... high-refractive-index layer | low-refractive-index layer | air, the outermost layer of the first (or second) layer is a low-refractive-index layer, and the total number of sub-layers is 2p (the greater the refractive index difference, the fewer the number of double-layer structures, and the smaller the overall layer thickness). Without considering absorption and scattering losses between layers, when the light beam is incident perpendicularly, the reflectivity at the center wavelength λ is:

[0064] .

[0065] Where, n g This is the refractive index of the substrate. As can be seen from the formula above, the refractive index ratio n... L / n HThe smaller the value, the more sub-layers there are, and the higher the reflectivity of the corresponding film system. For example, at a wavelength of 915 nm, the refractive index difference between SiO2 and Si3N4 is about 0.55, and the refractive index difference between SiO2 and TiO2 is about 1.15. To achieve the same 95% reflectivity, a combination of SiO2 and Si3N4 film layers requires 6 pairs (total thickness of about 1632 nm), while a combination of SiO2 and TiO2 film layers requires 5 pairs (total thickness of about 1228 nm).

[0066] The semiconductor laser chip 100 provided in this application embodiment has the following advantages:

[0067] 1) Through the special design of the first film layer 140 and the second film layer 150, dual-wavelength separation and bidirectional light output are achieved simply and effectively without adding any additional processes;

[0068] 2) The dual-sided light output configuration can achieve uniformity of optical power density and carrier density within the cavity, which helps to reduce problems such as spatial hole burning and two-photon absorption, thereby improving the output power of the laser chip;

[0069] 3) Compared with typical unidirectional light-emitting dual-junction chips, it avoids the problem of cavity surface temperature rise caused by close-range dual light spots at the cavity surface, and improves the reliability of the chip cavity surface while achieving the same light output power.

[0070] 4) Effective beam separation solves the problem of dark areas in two beams when light is emitted from one side, making it difficult to apply to practical scenarios. It increases the adjustment space of the dual-junction spacing and improves the chip's production tolerance and ease of use.

[0071] As can be seen, the semiconductor laser chip 100 provided in this application embodiment can effectively achieve dual-wavelength separation and bidirectional light output. While maintaining the feasibility of low-cost, high-efficiency mass production, it fully retains the advantage of doubled output power of dual-junction chips and maintains the high reliability characteristics close to those of single-junction chips. At the same time, it solves the problem of dark areas in single-sided light output, providing a guarantee for realizing high-brightness fiber coupling applications, and has significant advantages compared to traditional dual-junction chips.

[0072] The first film layer 140 and the second film layer 150 can be formed using a vapor deposition process. Before fabricating the first film layer 140 and the second film layer 150, the front cavity surface and the back cavity surface of the epitaxial wafer can be passivated. Both the first film layer 140 and the second film layer 150 can be multi-sub-film structures composed of alternating layers of sub-films made of high-refractive-index materials and low-refractive-index materials. After each sub-film layer is formed, a cleaning process is performed to avoid device power reduction and cavity surface temperature increase caused by photon absorption at the interface. When the first film layer 140 and the second film layer 150 are stacked multi-film structures, the interface between two adjacent first sub-film layers and second sub-film layers is the interface between the first sub-film layer and the second sub-film layer. The interface between the sub-film layers is relatively weak. If the peak electric field intensity is at the interface of the sub-film layers, it will have a significant impact on the quality of the first film layer 140 and the second film layer 150, and may easily lead to device failure. Therefore, in this embodiment, the peak electric field intensity in both the first film layer 140 and the second film layer 150 is not located at the sub-film layer interface, and both the first film layer 140 and the second film layer 150 have the characteristics of low stress, low absorption, high thermal conductivity, and high density. After the fabrication of the first film layer 140 and the second film layer 150 is completed, the semiconductor laser chip 100 is obtained. In addition, this application embodiment also provides a laser device, including the semiconductor laser chip 100 of the above embodiment. This laser device can be a display device, a laser printing device, an optical fiber communication device, a photoelectric detection device, etc.

[0073] Figure 3 This is a schematic diagram illustrating the arrangement of multiple semiconductor laser chips 100 in a laser device according to one embodiment of this application. Figure 3 As shown, the laser device in this embodiment includes multiple semiconductor laser chips 100 and an optical path coupling component. The optical path coupling component is used to combine the first beams emitted by each semiconductor laser chip 100 into a first bus beam 310, combine the second beams emitted by each semiconductor laser chip 100 into a second bus beam 320, and combine the first bus beam 310 and the second bus beam 320 into a total output beam 400. It can be understood that the semiconductor laser chips 100 and the optical path coupling component together constitute the laser emitting system of the laser device. The laser emitting system can emit at least one total output beam 400, enabling the laser emitted by the laser emitting system to couple into an optical fiber.

[0074] In this embodiment, the optical path coupling assembly includes multiple first optical devices 210, multiple second optical devices 220, a third optical device 230, and a fourth optical device 240. Each of the multiple first optical devices 210 corresponds one-to-one with a multiple semiconductor laser chip 100, and the first optical device 210 is used to change the propagation direction of the first beam emitted by the corresponding semiconductor laser chip 100 to form a first converging beam 310. Similarly, each of the multiple second optical devices 220 corresponds one-to-one with a multiple semiconductor laser chip 100, and the second optical device 220 is used to change the propagation direction of the second beam emitted by the corresponding semiconductor laser chip 100 to form a second converging beam 320. The third optical device 230 reflects one of the first converging beam 310 and the second converging beam 320 to the fourth optical device 240. The fourth optical device 240 modifies one of the first converging beam 310 and the second converging beam 320 and transmits the other of the first converging beam 310 and the second converging beam 320, so that the first converging beam 310 and the second converging beam 320 merge into a total output beam 400. In this embodiment, the first converging beam 310 is reflected by the third optical device 230 to the fourth optical device 240, and the fourth optical device 240 transmits the second converging beam 320 and reflects the first converging beam 310, so that the first converging beam 310 and the second converging beam 320 merge to form a total output beam 400.

[0075] In this embodiment, four semiconductor laser chips 100 are shown. Correspondingly, the optical path coupling assembly includes four first optical devices 210, four second optical devices 220, one third optical device 230, and one fourth optical device 240. The semiconductor laser chips 100 are arranged in a row, and the arrangement direction of the semiconductor laser chips 100 is parallel to the fast axis direction of the semiconductor laser chips 100. In other embodiments, the number of semiconductor laser chips 100 in the laser device can be increased or decreased as needed, and the number of first optical devices 210 and second optical devices 220 should also be increased or decreased accordingly.

[0076] In one embodiment, when the first quantum well layer 1122 and the second quantum well layer 1222 are respectively a compressive strain quantum well and a tensile strain quantum well; that is, when the quantum well structures of the first quantum well layer 1122 and the second quantum well layer 1222 are different, the semiconductor laser chip simultaneously supports TE mode and TM mode. Based on the polarization difference between TE mode and TM mode, the laser device can use polarization-sensitive optical elements (such as polarization beam splitters, waveplates or gratings) to separate (split), guide, and re-combine light of different polarization states, thereby realizing polarization multiplexing or integrated processing of multiple signals.

[0077] In summary, this application provides a semiconductor laser chip 100 and a laser device. The semiconductor laser chip 100 provided in this application includes an epitaxial wafer, a first film layer 140, and a second film layer 150. The epitaxial wafer includes a first light-emitting region 110 and a second light-emitting region 120 sequentially stacked along the fast axis of the semiconductor laser chip 100. A tunnel junction 130 is disposed between the first light-emitting region 110 and the second light-emitting region 120, and both the first light-emitting region 110 and the second light-emitting region 120 include a quantum well structure. The first film layer 140 is formed on the front cavity surface of the epitaxial wafer; the second film layer 150 is formed on the rear cavity surface of the epitaxial wafer. The first film layer 140 is used to transmit photons generated by the first light-emitting region 110 to form a first light beam and to reflect photons generated by the second light-emitting region 120; the second film layer 150 is used to transmit photons generated by the second light-emitting region 120 to form a second light beam and to reflect photons generated by the first light-emitting region 110. By setting the first film layer 140 and the second film layer 150 on the cavity surface with different orientations, the semiconductor laser chip 100 provided in this application embodiment can effectively achieve bidirectional light output. Therefore, it can reduce the thermal load on one side of the cavity surface, improve the reliability of the semiconductor laser chip 100, and make its reliability similar to that of a single-junction chip. Furthermore, since it is bidirectional light output, it avoids the problem of dark areas between adjacent light spots in unidirectional light output, and solves the problem that dark areas between two light spots in unidirectional light output make it difficult for the laser chip to be applied to practical scenarios. It also increases the adjustment space of the dual-junction spacing and improves the production tolerance and ease of use of the semiconductor laser chip 100.

[0078] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A semiconductor laser chip, characterized in that, It includes an epitaxial wafer, a first film layer (140), and a second film layer (150); The epitaxial wafer includes a first light-emitting region (110) and a second light-emitting region (120) arranged along the fast axis direction of the semiconductor laser chip (100). A tunnel junction (130) is provided between the first light-emitting region (110) and the second light-emitting region (120). Both the first light-emitting region (110) and the second light-emitting region (120) include a quantum well layer. The first film layer (140) is formed on the front cavity surface of the epitaxial wafer; the second film layer (150) is formed on the rear cavity surface of the epitaxial wafer; The first film layer (140) is used to transmit photons generated by the first light-emitting area (110) to form a first light beam and to reflect photons generated by the second light-emitting area (120); The second film layer (150) is used to transmit photons generated by the second light-emitting area (120) to form a second light beam and to reflect photons generated by the first light-emitting area (110).

2. The semiconductor laser chip according to claim 1, characterized in that, The wavelength of the first beam is 650~1000nm, and the wavelength of the second beam is 800~1200nm.

3. The semiconductor laser chip according to claim 2, characterized in that, The first film layer (140) has a reflectivity of less than 5% for photons generated by the first light-emitting region (110), and the second film layer (150) has a reflectivity of less than 5% for photons generated by the second light-emitting region (120). The reflectivity of the first film layer (140) to the photons generated by the second light-emitting area (120) is not less than 95%, and the reflectivity of the second film layer (150) to the photons generated by the first light-emitting area (110) is not less than 95%.

4. The semiconductor laser chip according to any one of claims 1-3, characterized in that, The light-emitting region includes an active layer disposed along the fast axis direction of the semiconductor laser chip (100), and a confinement layer is disposed on both the upper and lower sides of the active layer; The refractive index of each of the confinement layers is less than that of the active layer; The light-emitting area includes the first light-emitting area (110) and the second light-emitting area (120).

5. The semiconductor laser chip according to claim 4, characterized in that, The active layer includes an N-type waveguide layer, a quantum well layer, and a P-type waveguide layer stacked sequentially.

6. The semiconductor laser chip according to claim 5, characterized in that, The confinement layer, the N-type waveguide layer, and the P-type waveguide layer are made of AlGaAs, and the quantum well layer is made of GaAsP, InGaAs, or InAlGaAs.

7. The semiconductor laser chip according to claim 5, characterized in that, The thickness of the quantum well layer in the fast axis direction of the semiconductor laser chip (100) is 3~30nm.

8. The semiconductor laser chip according to claim 5, characterized in that, The active layer of the first light-emitting region includes a first quantum well layer (1122); the active layer of the second light-emitting region includes a second quantum well layer (1222). The first quantum well layer (1122) is a compressive strain quantum well or a tensile strain quantum well; the second quantum well layer (1222) is a compressive strain quantum well or a tensile strain quantum well; At least one of the first quantum well layer (1122) and the second quantum well layer (1222) is a tensile strain quantum well; and / or, at least one of the first quantum well layer (1122) and the second quantum well layer (1222) is a compressive strain quantum well.

9. The semiconductor laser chip according to any one of claims 1-3, characterized in that, The material of the tunnel junction (130) is GaAs; And / or, the thickness of the tunnel junction (130) in the fast axis direction of the semiconductor laser chip (100) is 20~200nm.

10. The semiconductor laser chip according to any one of claims 1-3, characterized in that, The first film layer (140) includes an overlapping first sub-film layer and a second sub-film layer, the difference between the refractive index of the first sub-film layer and the refractive index of the second sub-film layer is greater than or equal to 0.25, and the peak electric field intensity in the first film layer (140) is at the interface between the first sub-film layer and the second sub-film layer; And / or, the second film layer (150) includes an overlapping first sub-film layer and a second sub-film layer, the difference between the refractive index of the first sub-film layer and the refractive index of the second sub-film layer is greater than or equal to 0.25, and the peak electric field intensity in the first film layer (140) is not at the interface between the first sub-film layer and the second sub-film layer.

11. A laser device, characterized in that, Includes the semiconductor laser chip (100) according to any one of claims 1-10.

12. The laser device according to claim 11, characterized in that, The laser device includes a plurality of semiconductor laser chips (100) and an optical path coupling component. The optical path coupling component is used to combine the first beams emitted by each of the semiconductor laser chips (100) into a first converging beam (310), combine the second beams emitted by each of the semiconductor laser chips (100) into a second converging beam (320), and combine the first converging beam (310) and the second converging beam (320) into a total output beam (400).

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