TW202349812A - Multi-junction vertical resonant cavity surface emitting laser - Google Patents

Abstract

The invention provides a multi-junction vertical resonant cavity surface emitting laser, relates to the technical field of semiconductor lasers, and can adapt to a relatively large temperature range and realize continuous and stable working performance in the relatively large temperature range so as to reduce the influence of temperature change on device power and working stability. The laser comprises a substrate, a bottom reflecting layer arranged on the substrate, a multi-junction active region and a top reflecting layer, the multi-junction active region and the top reflecting layer are sequentially arranged in the hierarchical growth direction, the multi-junction active region comprises multiple layers of stacked quantum well structures, and in the multiple layers of stacked quantum well structures, the working wavelength ranges of at least two layers of quantum well structures are not overlapped. The working wavelength ranges of the multiple layers of quantum well structures jointly form the working wavelength range of the resonant cavity, so that the working wavelength range of the resonant cavity can be widened, the resonant cavity can adapt to a relatively large working temperature range, and the device can maintain relatively high luminous efficiency and stable working capability in the relatively large working temperature range.

Description

Multi-junction vertical resonant cavity surface emitting laser element

The invention relates to the technical field of semiconductor laser elements, and in particular to a multi-junction vertical resonant cavity surface-emitting laser element.

The vertical resonant cavity surface-emitting laser element (VCSEL) is mainly composed of three parts, the top distributed feedback Bragg cavity mirror (DBR), the active layer and the bottom distributed feedback Bragg cavity mirror (DBR). The optical thickness of its active layer is usually on the order of several wavelengths, which makes it easy to achieve single longitudinal mode and low threshold operation. It is easy to produce two-dimensional high-density arrays, realize two-dimensional optical interconnection and information processing, and vertical resonant cavity surface-emitting lasers. The radiating element has high modulation rate and is suitable for high-speed optical fiber communication systems and other related applications.

Multi-junction vertical resonant cavity surface-emitting laser element (Multi-Junction VCSEL) refers to a laser element in which multiple stacked active layers are connected in series using P+/N+ tunnel junctions. Since the active layers of the multi-layer stack are connected in series, under the same operating current, as long as the resistance of the tunnel junction is made small enough, the operating efficiency can be improved to match the active layer setting multiple. For example, for a single active layer vertical resonant cavity surface-emitting laser element, a transmission power to current conversion efficiency of 1 W/A is achieved. For a three-junction vertical resonant cavity surface-emitting laser element, or triple-junction VCSEL, It can achieve a transmission power to current conversion efficiency of 3 W/A. Therefore, the transmission power to current conversion efficiency is proportional to the number of stacked active layers. Under the same operating current, the multi-junction vertical resonant cavity surface-emitting laser Components are capable of outputting higher transmit power.

However, since the multi-junction vertical resonant cavity surface-emitting laser element is composed of a structure in which the light-emitting layers of multiple vertical cavity surface-emitting laser elements are vertically stacked, under the same current, it can produce equivalent multiples of optical power. Because of this, it will generate higher heat than a single-junction vertical resonant cavity surface-emitting laser element, making it easy to accumulate heat inside a multi-junction vertical resonant cavity surface-emitting laser element and cause a higher temperature rise, resulting in device power failure. Serious decline, which seriously hinders the multi-junction vertical resonant cavity surface-emitting laser components from maintaining stable performance during continuous operation.

The purpose of the embodiments of the present application is to provide a multi-junction vertical resonant cavity surface-emitting laser element that can adapt to a larger temperature range and achieve sustained and stable high-power operating performance in a larger temperature range to reduce the impact of temperature changes on device power and operating stability.

In one aspect of the embodiment of the present application, a multi-junction vertical resonant cavity surface-emitting laser element is provided, including a substrate, a bottom reflective layer provided on the substrate, and a multi-junction active layer sequentially provided along the layer growth direction. and a top reflective layer. The multi-junction active layer includes a superimposed multi-layer quantum well structure. Among the superimposed multi-layer quantum well structures, the operating wavelength ranges of at least two layers of the quantum well structures do not overlap.

In a possible implementation of the present application, the multi-layer quantum well structure at least includes a first quantum well structure and a second quantum well structure, wherein the first quantum well structure has a first operating wavelength range, and the third quantum well structure The two quantum well structure has a second operating wavelength range, and the first operating wavelength range and the second operating wavelength range do not overlap.

In a possible implementation of the present application, the multi-layer quantum well structure further includes a third quantum well structure, the third quantum well structure has a third operating wavelength range, the second operating wavelength range and the third operating wavelength range. The wavelength ranges are respectively located on the long wavelength side and the short wavelength side of the first operating wavelength range.

In a possible implementation of the present application, the working wavelength ranges of at least two layers of the quantum well structures are adjacent.

In a possible implementation of the present application, the operating wavelength ranges of the multiple layers of the quantum well structure are discontinuous.

In a feasible implementation of the present application, the multi-layer quantum well structure is divided into at least two groups along the layer growth direction, each group contains at least two layers of the quantum well structure, and the operation of the quantum well structure in each group The wavelength ranges are the same, and the working wavelength ranges of at least two groups of quantum well structures do not overlap.

In a feasible implementation of the present application, the multi-layer quantum well structure at least includes a first quantum well structure group and a second quantum well structure group, wherein all quantum wells in the first quantum well structure group have In the first operating wavelength range, all quantum wells in the second quantum well structure group have the second operating wavelength range, and the first operating wavelength range does not overlap with the second operating wavelength range.

In a feasible implementation of the present application, the multi-layer quantum well structure further includes a third quantum well structure group, and all quantum wells in the third quantum well structure group have the third operating wavelength range, and the second The working wavelength range and the third working wavelength range are respectively located on the long wavelength side and the short wavelength side of the first working wavelength range.

In a feasible implementation of the present application, the working wavelength ranges of at least two quantum well structure groups are adjacent, or the working wavelength ranges of multiple quantum well structure groups are discontinuous.

In a possible implementation of the present application, the bottom reflective layer and/or the top reflective layer is a dispersed Bragg reflector.

In a possible implementation of the present application, the dispersed Bragg reflector includes a conductive P-type dispersed Bragg reflector and a conductive N-type dispersed Bragg reflector.

In a feasible implementation of the present application, the multi-junction active layer is divided into a plurality of sub-multi-junction active layers spaced apart from each other in the direction of the hierarchical plane to achieve light emitting from the laser beam array.

In a feasible implementation of the present application, the multi-junction vertical resonant cavity surface-emitting laser element has a bottom-emitting structure or a top-emitting structure.

The multi-junction vertical resonant cavity surface-emitting laser element provided by the embodiment of the present application includes the substrate, the bottom reflective layer provided on the substrate, the multi-junction active layer and the top reflective layer arranged sequentially along the layer growth direction. , the multi-junction active layer includes superimposed multiple layers of the quantum well structure, and among the superimposed multiple layers of the quantum well structure, the operating wavelength ranges of at least two layers of the quantum well structures do not overlap. A multi-junction VCSEL structure formed on the substrate including the bottom reflective layer, the multi-junction active layer and the top reflective layer is used for stimulated radiation and resonant emission of laser beams. For the quantum well structure, The wavelength is greatly affected by the drift of temperature changes, while the wavelength of the resonant cavity is relatively less affected by changes in temperature. The working wavelength ranges of at least two layers of the quantum well structure in the multi-layer quantum well structure do not overlap. The working wavelength range of the multi-layer quantum well structure jointly forms the working wavelength range of the resonant cavity, which can broaden the working wavelength range of the resonant cavity, which is more conducive to adapting to a larger operating temperature range, so that the device can operate in a larger It can maintain high luminous efficiency and stable working ability within the temperature range.

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.

In the description of this application, it should be noted that the orientation or positional relationship indicated by the terms "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or is where the product of this application is commonly used. The orientation or positional relationship is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", etc. are only used to differentiate descriptions and are not to be understood as indicating or implying relative importance.

It should also be noted that, unless otherwise clearly stated and limited, the terms "setting" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection. Connected, it can also be connected indirectly through an intermediary, or it can be an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood on a case-by-case basis.

Vertical resonant cavity surface-emitting laser elements refer to devices that are stacked in a direction perpendicular to the substrate surface to form energy excitation and resonance amplification to emit laser. The laser beam generated by the vertical resonant cavity surface-emitting laser element is oriented perpendicular to the substrate surface. The direction of the laser beam emitted is different from that of the edge-emitting laser. Due to this difference, the formation structure and preparation process of the vertical resonant cavity surface-emitting laser element enable the vertical resonant cavity surface-emitting laser element to support "on-wafer" testing at each node of the preparation process, giving full play to It understands the role of device performance testing on the production yield during the preparation process, effectively improving the production yield of vertical resonant cavity surface-emitting laser components. Moreover, since the laser beam is emitted from the top or bottom surface, based on the need to increase device power, vertical resonant cavity surface-emitting laser elements can be produced in a two-dimensional array, thereby realizing a two-dimensional planar array of surface light sources.

Compared with the single-junction vertical resonant cavity surface-emitting laser element, the multi-junction vertical resonant cavity surface-emitting laser element can significantly improve the emission power to current conversion efficiency of the laser element. However, due to the multi-junction vertical resonant cavity surface The multi-layer quantum well structure is stacked in the emitting laser element, and the tunnel junction is connected to the quantum well structure. The multi-junction vertical resonant cavity surface-emitting laser element will generate more heat during operation, and the heat generated by the heat will Difficulty in rapid dispersion and cooling will cause the temperature of the multi-junction vertical resonant cavity surface-emitting laser element itself and the working environment to rise rapidly. Since semiconductor laser elements are affected by temperature, temperature changes (rise or fall) cause A certain degree of wavelength drift will have a negative impact on the power of the multi-junction vertical resonant cavity surface-emitting laser element, resulting in a serious reduction in power and making the performance of the multi-junction vertical resonant cavity surface-emitting laser element unstable. Figure 1 is a schematic diagram showing how the operating efficiency of a multi-junction vertical resonant cavity surface-emitting laser element changes with temperature. As shown in Figure 1, the thick line shows the operation of the multi-junction vertical resonant cavity surface-emitting laser element at 20°C. The efficiency changes with the operating current. The thin line is the operating efficiency of the multi-junction vertical resonant cavity surface emitting laser at 80°C. It can be seen from Figure 1 that at an operating current of 10mA, when When the temperature rises from 20°C to 80°C, the working efficiency of the multi-junction vertical resonant cavity surface-emitting laser element drops to 70% of the original value.

The embodiment of the present application provides a multi-junction vertical resonant cavity surface-emitting laser element. Figure 2 is a schematic diagram of the hierarchical structure of the multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application. As shown in Figure 2, The multi-junction vertical resonant cavity surface-emitting laser element includes a substrate 10, a bottom reflective layer 20 provided on the substrate 10, a multi-junction active layer and a top reflective layer 40 arranged sequentially along the layer growth direction. The multi-junction active layer includes superimposed multi-layer quantum well structures 30. Among the superimposed multi-layer quantum well structures 30, the working wavelength ranges of at least two layers of the quantum well structures 30 do not overlap.

The multi-junction vertical resonant cavity surface-emitting laser element can be divided into a top-emitting structure and a bottom-emitting structure according to the different directions of the outgoing laser beam caused by its structural settings. The multi-junction vertical resonant cavity surface-emitting laser element of the top-emitting structure The laser beam formed after the light beam excited by the laser element is resonantly amplified by the resonant cavity is emitted through the top reflective layer 40 at the top. The substrate 10 of the multi-junction vertical resonant cavity surface-emitting laser element of the bottom-emitting structure has been structurally processed such as thinning, removal or opening. The laser beam formed after the beam is resonantly amplified by the resonant cavity passes through the bottom of the resonant cavity. The bottom reflection layer 20 then emits from the bottom side. As an example, what is shown in Figure 2 is a multi-junction vertical resonant cavity surface-emitting laser element with a top-emitting structure. The multi-junction vertical resonant cavity surface-emitting laser element with a top-emitting structure will be described in detail below.

As shown in Figure 2, in the multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application, the multi-junction active layer includes multiple stacked active layers, and each active layer includes a quantum well structure 30 and a tunnel junction. , two adjacent quantum well structures 30 of the active layer are connected in series through tunnel junctions. Persons skilled in the art should know that the multi-junction vertical resonant cavity surface-emitting laser element also includes other laser implementations that are not mentioned. The corresponding hierarchical structure required by the functional principle of the radiating element, such as the electrode layer, contact layer, etc. used to form a voltage to excite the light beam. In this application, there is no special limitation on the above hierarchical structure, which means that the above-mentioned hierarchical structure is used in the embodiments of this application. In the multi-junction vertical resonant cavity surface-emitting laser element, the arrangement of this type of structure can have the same arrangement and function as the existing vertical resonant cavity surface-emitting laser element. Therefore, there is no special limitation and does not mean that this application The multi-junction vertical resonant cavity surface-emitting laser element of the embodiment does not have these hierarchical structures. The corresponding explanation will be given below in conjunction with the working process of the multi-junction vertical resonant cavity surface-emitting laser element.

As shown in FIG. 2 , a bottom reflective layer 20 and a multi-junction active layer are disposed on the substrate 10 . The multi-junction active layer includes a plurality of stacked active layers, and each active layer includes a quantum well structure. 30. Two adjacent quantum well structures 30 of the active layer are connected in series through tunnel junctions. For example, the multi-junction active layer in Figure 2 includes four layers of the quantum well structure 30, and in the multi-junction active layer The layer also includes an oxide layer for providing photoelectric confinement. A top reflective layer 40 is provided on the quantum well structure 30 of the uppermost layer. The bottom reflective layer 20, the multi-layer quantum well structure 30, and the quantum well structures 30 are The sandwich-like structure formed between the tunnel junction and the top reflective layer 40 serves as a multi-junction active layer. Among the four-layer quantum well structures 30, the operating wavelength ranges of at least two of the quantum well structures 30 do not overlap. . A lower electrode 60 is also provided on the substrate 10 , and an upper electrode 70 is also provided on the top reflective layer 40 . The lower electrode 60 and the upper electrode 70 serve as anode contact and cathode contact respectively. Through external energy (light energy or Electric energy) forms an electric field between the lower electrode 60 and the upper electrode 70. When forward biased, carriers are generated in the tunnel junction, injected and localized in the quantum well structures 30 to recombine and emit light, as shown in Figure 2 It is shown that since the multi-junction vertical resonant cavity surface-emitting laser element in this embodiment has a top-emitting structure and the laser beam is emitted from the top, an opening is formed on the upper electrode 70 to facilitate the emission of the laser beam.

In the preparation process of the multi-junction vertical resonant cavity surface-emitting laser element in the embodiment of the present application, the multi-junction vertical resonant cavity surface-emitting laser element is processed by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). ) process to deposit a complex multi-layer film structure on the substrate 10. For example, in this embodiment, as shown in FIG. 2 , the quantum well structures 30 in the multi-junction active layer include four layers. In at least two of the layers, the operating wavelength of the quantum well structures 30 The ranges do not overlap, and the operating wavelength range refers to the wavelength range in which the quantum well structure 30 recombines light under the action of external energy. In this way, the working wavelength range of the composite light emitted by the two layers of the quantum well structure 30 is different, and the working wavelength range of the resonant cavity including the multi-layered quantum well structure 30 is expanded. Since the wavelength of the quantum well drifts with temperature drift, The coefficient is about 0.27nm/°C, and the wavelength of the resonant cavity changes with temperature drift to 0.07nm/°C. Therefore, the working wavelength range of some layers in the multi-layer quantum well structure 30 is adjusted to the short-wave direction, and the working wavelength range of the other part of the layer is adjusted to the shortwave direction. As long as the wavelength range remains unchanged, the stable operating temperature range of the multi-junction vertical resonant cavity surface-emitting laser element can be expanded to a certain limit in the direction of high temperature. On the contrary, a part of the multi-layer quantum well structure 30 By adjusting the working wavelength range of one layer to the long wave direction, while keeping the working wavelength range of the other layers unchanged, the stable operating temperature range of the multi-junction vertical resonant cavity surface-emitting laser element can be expanded to a certain extent towards low temperatures. border.

If the multi-junction vertical resonant cavity surface-emitting laser element of the embodiment of the present application needs to have better working performance and stable working state within a temperature range that differs by 100°C, the element needs to be able to overcome this difference of 100°C. °C temperature change, and it is also necessary to consider the impact of the heat generated by working and adding current on the temperature during this period of temperature change with a difference of 100 °C.

For example, if the problem of heat generation and poor heat dissipation of the multi-junction vertical resonant cavity surface-emitting laser element is taken into account, it is necessary to make the multi-junction vertical resonant cavity surface-emitting laser element capable of raising the temperature by 100°C under the existing adaptive temperature state. It can work efficiently and stably within the range, and the working wavelength range of one or several layers in the multi-layer quantum well structure 30 can be adjusted. Taking the four-layer quantum well structure 30 as shown in Figure 2 as an example, at least four layers of the quantum well structure 30 can operate efficiently and stably within the range. Among the two layers of the quantum well structure 30, one layer of the quantum well structure 30 has an originally preset operating wavelength range, and the operating wavelength range of the other layer of the quantum well structure 30 is adjusted to the short wavelength side. About 30nm, which does not overlap with the original operating wavelength range, so that after wavelength adjustment, the multi-junction vertical resonant cavity surface-emitting laser element can maintain optimal performance within a 100°C temperature rise range under the existing adaptive temperature conditions. The working efficiency is such that temperature rise within this range will not have a serious impact on the efficient and stable operation of the device.

For another example, if we consider some special applications of the multi-junction vertical resonant cavity surface-emitting laser element, the multi-junction vertical resonant cavity surface-emitting laser element needs to work in a low-temperature environment, such as -40°C. To maintain better working performance, still taking the four-layer quantum well structure 30 shown in Figure 2 as an example, at least in two of the four-layer quantum well structures 30, one layer of the quantum well structure 30 is the original default The working wavelength range of the other layer of the quantum well structure 30 is adjusted, and the working wavelength range is adjusted to the long wavelength side by about 10 nm, so that it does not overlap with the original working wavelength range, so that after the wavelength adjustment The multi-junction vertical resonant cavity surface-emitting laser element can adapt to temperature environments ranging from normal temperature to -40°C, and can maintain good working efficiency in this temperature range.

It should be noted that in the multi-junction vertical resonant cavity surface-emitting laser element in the embodiment of the present application, the aforementioned one-layer quantum well structure 30 does not necessarily refer to a single physical hierarchical structure. For example, it can also be understood that : One layer of the quantum well structure 30 includes an overall layer formed by stacking multiple quantum wells and tunnel junctions. That is, the one layer of quantum well structure 30 may include a stacked structure of multiple quantum wells and tunnel junctions. .

Figure 4 is a comparison chart of the relative output power affected by temperature between the multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application and the multi-junction vertical resonant cavity surface-emitting laser element in the prior art, as shown in Figure 4 , the thick fold line is the simulated fold line of the relative output power of the multi-junction vertical resonant cavity surface-emitting laser element in the embodiment of the present application in the range of -40°C to 120°C, and the thin fold line is the multi-junction vertical resonant cavity of the prior art. The simulated fold line of the relative output power of the surface-emitting laser element in the range of -40°C to 120°C can be seen from Figure 4. The multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application passes In the multi-layer quantum well structure 30, part of the quantum well structure 30 is set with an operating wavelength range adjusted toward the long wavelength direction, and part of the quantum well structure 30 is set with an operating wavelength range adjusted toward the short wavelength direction, so that the relative output power It can effectively improve the stability of the output power in the temperature range of -40°C to 120°C, and can achieve better improvement results in both low-temperature and high-temperature environments.

It should be noted that there are many ways to adjust the working wavelength range of the quantum well structures 30, such as changing the thickness of the quantum well structures 30, changing the forming materials or components of the quantum well structures 30, etc., using the above Any method, or a combination of two or more methods, can realize the adjustment of the operating wavelength range of the quantum well structures 30 .

The multi-junction vertical resonant cavity surface-emitting laser element provided by the embodiment of the present application includes the substrate 10, the bottom reflective layer 20 provided on the substrate 10, the multi-junction active layer sequentially provided along the layer growth direction, and The top reflective layer 40 and the multi-junction active layer include stacked multiple layers of the quantum well structures 30. Among the stacked multiple layers of the quantum well structures 30, the operating wavelength ranges of at least two layers of the quantum well structures 30 do not overlap. The multi-junction VCSEL structure formed on the substrate 10 including the bottom reflective layer 20, the multi-junction active layer and the top reflective layer 40 is used for stimulated radiation and resonant emission of laser beams. For the quantum well structure 30 Generally speaking, its wavelength is greatly affected by the drift of temperature changes, while the wavelength of the resonant cavity is relatively less affected by changes in temperature. The work of arranging at least two layers of the quantum well structure 30 in the multi-layer quantum well structure 30 is The wavelength ranges do not overlap. The working wavelength ranges of the multiple layers of the quantum well structure 30 jointly form the working wavelength range of the resonant cavity. This can broaden the working wavelength range of the resonant cavity, which is more conducive to adapting to a larger working temperature range. This enables the components to maintain high luminous efficiency and stable working capabilities within a larger operating temperature range.

In a feasible implementation of the present application, the multi-layer quantum well structure 30 includes at least a first quantum well structure 31 and a second quantum well structure 32, wherein the first quantum well structure 31 has a first operating wavelength. range, the second quantum well structure 32 has a second operating wavelength range, and the first operating wavelength range does not overlap with the second operating wavelength range.

Figure 3 is the second schematic diagram of the hierarchical structure of the multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application. As shown in Figure 3, in the multi-junction vertical resonant cavity surface-emitting laser element of this embodiment, the multi-layer The quantum well structure 30 includes a first quantum well structure 31 and a second quantum well structure 32 on the first quantum well structure 31, wherein the operating wavelength range of the first quantum well structure 31 is the first operating wavelength range. The operating wavelength range of the second quantum well structure 32 is the second operating wavelength range, and the first operating wavelength range does not overlap with the second operating wavelength range. In this way, the multi-junction vertical in this embodiment The resonant cavity surface-emitting laser element can maintain stable operation within the temperature range corresponding to the first operating wavelength range and the second operating wavelength range, thereby expanding the multi-junction vertical resonant cavity surface of this embodiment. Stable operating temperature range of radiated laser components. For example, in the embodiment of the present application, the multi-junction vertical resonant cavity surface-emitting laser element is equipped with a tunnel junction with low resistance and low absorption, and is tuned through layers, so that the multi-layer quantum well structure 30 and the tunnel junction are aligned with the standing wave. .

Similarly, the second quantum well structure 32 on the first quantum well structure 31 does not necessarily refer to a single entity hierarchical structure. It can be understood as a single quantum well structure 30, or it can also be understood as including multiple quantum well structures. An overall stacked structure formed by stacking quantum wells and tunnel junctions. The following third quantum well structure 33 and so on can all be understood equally.

In a possible implementation of the present application, as still shown in FIG. 3 , the multi-layer quantum well structure 30 also includes a third quantum well structure 33 , and the third quantum well structure 33 has a third operating wavelength range. The second operating wavelength range and the third operating wavelength range are respectively located on the long wavelength side and the short wavelength side of the first operating wavelength range.

As shown in Figure 3, the multi-junction vertical resonant cavity surface-emitting laser element of this embodiment includes the multi-junction active layer provided on the substrate 10. The multi-junction active layer includes the bottom reflection layer arranged in sequence. 20. The third quantum well structure 33, the first quantum well structure 31, the second quantum well structure 32, the top reflective layer 40, the first quantum well structure 31, the second quantum well structure 32 and the third The three quantum well structures 33 are respectively the first operating wavelength range, the second operating wavelength range and the third operating wavelength range, wherein the second operating wavelength range and the third operating wavelength range are respectively located at the first operating wavelength range. The long wavelength side and the short wavelength side of the range, that is to say, the second operating wavelength range of the second quantum well structure 32 and the third operating wavelength range of the third quantum well structure 33 are respectively from the long wavelength side. The wavelength side and the short wavelength side expand the stable operating wavelength range of the multi-junction vertical resonant cavity surface-emitting laser element of this embodiment, that is, the stable operating temperature range of the multi-junction vertical resonant cavity surface-emitting laser element is also respectively A certain degree of expansion is achieved in the direction of temperature increase and temperature decrease, so that the adjusted stable operating temperature range is expanded, and stable operation can be maintained with a certain degree of temperature decrease and temperature increase.

It should be noted that in the schematic structural diagram shown in FIG. 3 , the second quantum well structure 32 is located above the first quantum well structure 31 , and the third quantum well structure 33 is located on the first quantum well structure. 31, this is shown as an example. In fact, the positional relationship between the quantum well structures 30 with different operating wavelength ranges can be adjusted, exchanged or changed, and is not limited to the above example and the view in Figure 3 exhibit.

In a feasible implementation of the present application, the working wavelength ranges of at least two layers of the quantum well structure 30 are adjacent to each other. The working wavelength ranges of the two quantum well structures 30 are adjacent to each other, that is, the maximum value of the working wavelength range of one quantum well structure 30 is the same as the minimum value of the working wavelength range of the other quantum well structure 30 , or alternatively, The minimum value of the working wavelength range of one quantum well structure 30 is the same as the maximum value of the working wavelength range of the other quantum well structure 30. The two working wavelength ranges are directly continuous to form a large working wavelength range.

In another feasible implementation of the present application, the operating wavelength ranges of the multiple layers of the quantum well structure 30 are discontinuous. Normally, the multi-layer quantum well structure 30 can be formed by crystal growth. In order to achieve the largest possible stable operating temperature range in the limited levels of the quantum well structure 30, the operating wavelength of the multi-layer quantum well structure 30 is set. The ranges are discontinuous, so that in the multi-layer quantum well structure 30, the maximum value of the long wavelength and the minimum value of the short wavelength in the operating wavelength are as far apart as possible, so that the multi-junction with the multi-layer quantum well structure 30 The vertical resonant cavity surface-emitting laser element operates stably within the operating temperature range that is satisfied by the difference between the maximum value of the long wavelength and the minimum value of the short wavelength. The multi-layer quantum well structure in the embodiment of the present application may use strained InGaAs multi-quantum wells.

In a feasible implementation of the present application, the multi-layer quantum well structure 30 is divided into at least two groups, each group contains at least two layers of the quantum well structure 30, and the operation of the quantum well structure 30 in each group is The wavelength ranges are the same, and the working wavelength ranges of at least two sets of quantum well structures 30 do not overlap. That is, multiple layers of the quantum well structures 30 are grouped, and at least two layers of the quantum well structures 30 in each group have the same operating wavelength range. A group of the quantum well structures 30 can be regarded as a combination, and different settings can be made through multiple combinations. The operating wavelength range enables the device to operate efficiently and stably in a wide temperature range.

In a feasible implementation of the present application, the multi-layer quantum well structure 30 includes at least a first quantum well structure group and a second quantum well structure group, wherein all quantum wells in the first quantum well structure group are Having the first operating wavelength range, all quantum wells in the second quantum well structure group have the second operating wavelength range, and the first operating wavelength range does not overlap with the second operating wavelength range.

In a feasible implementation of the present application, the multi-layer quantum well structure 30 also includes a first three quantum well structure group, and all quantum wells in the third quantum well structure group have the third operating wavelength range, and the third quantum well structure group has the third operating wavelength range. The second operating wavelength range and the third operating wavelength range are respectively located on the long wavelength side and the short wavelength side of the first operating wavelength range.

In a feasible implementation of the present application, the working wavelength ranges of at least two quantum well structure groups are adjacent, or the working wavelength ranges of multiple quantum well structure groups are discontinuous.

The above is the limitation of the working wavelength range of the quantum well according to the inventive concept of the embodiment of the present application after the multi-layer quantum well structure 30 is divided into groups.

In a possible implementation of the present application, the bottom reflective layer 20 and/or the top reflective layer 40 is a Distributed Bragg Reflector (DBR for short). The dispersed Bragg reflector includes a conductive P-type dispersed Bragg reflector and a conductive N-type dispersed Bragg reflector.

It should be noted that the bottom reflective layer 20 is a dispersed Bragg reflector. First, a laterally uniform crystal layer can be grown on the substrate 10 of N-type gallium arsenide material to form a high refractive index film layer and a low refractive index film. The multi-layer structure of alternately stacked high-refractive index film layers and low-refractive index film layers is a dispersed Bragg reflector of the bottom reflective layer 20. Similarly, the top reflective layer 40 is a dispersed Bragg reflector. The Bragg reflector can be a multi-layer structure in which high refractive index film layers and low refractive index film layers are alternately stacked using chemical vapor deposition.

The bottom reflective layer 20 and the top reflective layer 40 are respectively provided on the upper and lower sides of the quantum well structure 30. The sandwich-like structure formed together with the quantum well structure 30 is the multi-junction active layer. The quantum well The light beam formed by the structure 30 being excited by the external energy oscillates and is amplified in the multi-junction active layer. The bottom reflective layer 20 and the top reflective layer 40 serve as laser cavity mirrors. The beam is repeatedly reflected between the two laser cavity mirrors, and is reflected during reflection. During the process, light energy is absorbed and a resonance effect is produced, which continuously amplifies the light energy to form a laser beam.

The bottom reflective layer 20 and/or the top reflective layer 40 may use dispersed Bragg reflectors. For example, the substrate 10 can be made of gallium arsenide material; the bottom reflection layer 20 includes the conductive N-type dispersed Bragg reflector, and the material can be aluminum gallium arsenide; the material of the quantum well structure 30 can be aluminum gallium arsenide and A heterojunction structure formed by indium gallium arsenide; the top reflective layer 40 includes the conductive P-type dispersed Bragg reflector, and the material may be aluminum gallium arsenide.

In addition, corresponding hierarchical structures such as oxide layers and isolation layers can also be provided in the multi-junction vertical resonant cavity surface-emitting laser element in the embodiment of the present application to realize its known functions, which will not be described in detail here.

In a feasible implementation of the present application, the multi-junction active layer is divided into a plurality of sub-multi-junction active layers spaced apart from each other in the direction of the hierarchical plane to achieve light emitting from the laser beam array.

The multi-junction active layer can be divided into multiple sub-multi-junction active layers in the direction of the hierarchical plane. Two adjacent sub-multi-junction active layers are separated from each other, so that each sub-multi-junction active layer can achieve excitation beam and resonance amplification respectively. The function is to emit the laser beam, thereby realizing the array emission of the entire multi-junction vertical resonant cavity surface-emitting laser element emitting surface.

In another possible implementation of the present application, the multi-junction vertical resonant cavity surface-emitting laser element may also be a bottom-emitting structure. Figure 5 is the third schematic diagram of the hierarchical structure of the multi-junction vertical resonant cavity surface-emitting laser according to the embodiment of the present application. As shown in Figure 5, the multi-junction vertical resonant cavity surface-emitting laser element of the bottom-emitting structure excites the emitted laser. The laser beam emerges from the bottom window. In order to ensure the light extraction efficiency of the laser beam, the material of the substrate 10 can be selected to be a light-transmitting material or the bottom window can be made of a light-transmitting material, or the thickness of the substrate 10 can be reduced. For example, the thickness of the substrate 10 is reduced to less than 150 μm to reduce the absorption loss of the outgoing laser beam by the substrate 10 as a bottom window. In addition, the quality of the outgoing laser beam can be improved by growing an anti-reflection film. At the same time, flip-chip technology and corresponding packaging technology can also be used to support the implementation of bottom-emitting structures. For example, the multi-junction vertical resonant cavity surface-emitting laser element can usually be realized using a bottom-emitting structure in the 976-1064 nm band.

The multi-junction vertical resonant cavity surface-emitting laser element provided by the embodiment of the present application adjusts the working wavelength range of at least two layers of the quantum well structure 30 in the multi-layer quantum well structure 30, so that at least two layers of the quantum well structure 30 can The working wavelength ranges of the well structures 30 do not overlap, so that the multi-junction vertical resonant cavity surface-emitting laser element provided by the embodiment of the present application can have better output power and stable operation in a larger temperature range. sex. Among them, specific settings can be made according to the specific application field of the multi-junction vertical resonant cavity surface-emitting laser element in the embodiment of the present application and the temperature and other environments it may be in. If it is to be used in a low-temperature environment lower than normal temperature for a long time, By working, the working wavelength range of a part of the quantum well structure 30 can be adjusted to a certain distance in the long wavelength direction. If it is in an environment with poor heat dissipation at normal temperature, or works in a high temperature environment, the working wavelength range of part of the quantum well structure 30 can be adjusted to a short wavelength direction by a certain distance. If the working environment is harsh and the ambient temperature may be in a relatively wide range, such as -40°C to 120°C, the working wavelength range of part of the quantum well structure 30 can be adjusted to a short wavelength direction by a certain distance. Another part of the operating wavelength range of the sub-well structure 30 is adjusted by a certain distance toward the long wavelength direction, and a part of the operating wavelength range of the quantum well structure 30 remains unchanged.

The multi-junction vertical resonant cavity surface-emitting laser element provided by the embodiment of the present application can adjust the temperature range in which it can operate stably at high power. The application of the multi-junction vertical resonant cavity surface-emitting laser element provided by the embodiment of the present application As a sensing device for the Internet of Things or as a device for data center implementation of cloud computing, it can provide higher output power and maintain stable working capabilities when in an environment with poor heat dissipation. When used in 3D imaging of consumer electronics devices, such as 3D face recognition using infrared dot matrix projectors, the device can be used in various outdoor temperature environments to ensure recognition accuracy.

In particular, when the multi-junction vertical resonant cavity surface-emitting laser element provided by the embodiment of the present application is used in communication sensors, laser radar, etc. in automatic driving of automobiles, due to the harsh driving environment of automobiles, it is more necessary to be able to The multi-junction vertical resonant cavity surface-emitting laser element achieves stable operation in a wider temperature range and improves the safety of autonomous vehicle driving through the stable operation of communication sensors or laser radars.

The above are only examples of the present application and are not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included in the protection scope of this application.

10: Base 20: Bottom reflective layer 30: Quantum well structure 31: First quantum well structure 32: Second quantum well structure 33: The third quantum well structure 40:Top reflective layer 60: Lower electrode 70: Upper electrode

Figure 1 is a schematic diagram showing the working efficiency of a multi-junction vertical resonant cavity surface-emitting laser element as it changes with temperature. FIG. 2 is a schematic diagram of the hierarchical structure of a multi-junction vertical resonant cavity surface-emitting laser element according to an embodiment of the present application. FIG. 3 is the second schematic diagram of the hierarchical structure of the multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application. Figure 4 is a comparison diagram of the relative output power affected by temperature between the multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application and the multi-junction vertical resonant cavity surface-emitting laser element in the prior art. FIG. 5 is a third schematic diagram of the hierarchical structure of the multi-junction vertical resonant cavity surface-emitting laser element according to the embodiment of the present application.

10: Base

20: Bottom reflective layer

30: Quantum well structure

40:Top reflective layer

60: Lower electrode

70: Upper electrode

Claims (10)

A multi-junction vertical resonant cavity surface-emitting laser element, which is characterized by including: A substrate, a bottom reflective layer arranged on the substrate, a multi-junction active layer and a top reflective layer arranged sequentially along the layer growth direction. The multi-junction active layer includes a superimposed multi-layer quantum well structure, and the superimposed multi-layer quantum well structure is In the well structure, the operating wavelength ranges of at least two layers of the quantum well structure do not overlap. The multi-junction vertical resonant cavity surface emitting laser element as claimed in claim 1, wherein the multi-layer quantum well structure at least includes a first quantum well structure and a second quantum well structure, wherein the first quantum well structure Having a first operating wavelength range, the second quantum well structure has a second operating wavelength range, and the first operating wavelength range and the second operating wavelength range do not overlap. The multi-junction vertical resonant cavity surface-emitting laser element as claimed in claim 2, wherein the multi-layer quantum well structure further includes a third quantum well structure, and the third quantum well structure has a third operating wavelength range, and the The second operating wavelength range and the third operating wavelength range are respectively located on the long wavelength side and the short wavelength side of the first operating wavelength range. The multi-junction vertical resonant cavity surface-emitting laser element according to claim 1, wherein the operating wavelength ranges of at least two layers of the quantum well structures are adjacent. The multi-junction vertical resonant cavity surface-emitting laser element according to claim 1, wherein the operating wavelength ranges of the multi-layer quantum well structures are discontinuous. The multi-junction vertical resonant cavity surface-emitting laser element as described in claim 1, wherein the multi-layer quantum well structure is divided into at least two groups along the layer growth direction, and each group contains at least two layers of the quantum well structure. The working wavelength ranges of the quantum well structures in one group are the same, and the working wavelength ranges of the quantum well structures in at least two groups do not overlap. The multi-junction vertical resonant cavity surface-emitting laser element as claimed in claim 1, wherein the bottom reflective layer and/or the top reflective layer is a dispersed Bragg reflector. The multi-junction vertical resonant cavity surface-emitting laser element as claimed in claim 7, wherein the distributed Bragg reflector includes a conductive P-type distributed Bragg reflector and a conductive N-type distributed Bragg reflector. The multi-junction vertical resonant cavity surface-emitting laser element as claimed in claim 1, wherein the multi-junction active layer is divided into a plurality of sub-multi-junction active layers spaced apart from each other in the layer plane direction to realize laser beam array emission. The multi-junction vertical resonant cavity surface-emitting laser element according to claim 1, wherein the multi-junction vertical resonant cavity surface-emitting laser element has a bottom-emitting structure or a top-emitting structure.

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