Laser architecture using quantum well mixing technology

Abstract

The present disclosure relates to laser architectures using quantum well mixing technology. The present invention discloses a laser chip including a plurality of stripes, wherein the laser stripes can be grown using an initial optical gain distribution, and its optical gain distribution can be offset by using a mixing process. In this way, a plurality of laser stripes can be formed from the same epitaxial wafer on the same laser chip, wherein at least one laser stripe can have an optical gain distribution that is offset relative to another laser stripe. For example, each laser stripe can have an offset optical gain distribution relative to its adjacent laser stripes, so that each laser stripe can emit light having a different wavelength range. The laser chip can emit light over a wide range of wavelengths. Examples of the present disclosure also include different regions of a given laser stripe having different amounts of mixing.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a divisional application of the invention patent application with international application number PCT / US2018 / 052679, international application date September 25, 2018, date of entry into the Chinese national phase March 27, 2020, Chinese national application number 201880063497.8, and invention name “Laser architecture using quantum well hybrid technology”.

[0003] This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 564,419, filed on September 28, 2017, the entire disclosure of which is incorporated herein by reference for all purposes. Technical Field

[0004] The present disclosure generally relates to semiconductor lasers formed using quantum well intermixing (QWI). More specifically, the present disclosure relates to semiconductor laser chips including multiple QWI laser stripes having different optical gain offsets. Background Art

[0005] Semiconductor lasers can be used in many applications such as trace gas detection, environmental monitoring, biomedical diagnostics, telecommunications, and industrial process control. Some applications can benefit from systems that can emit light over a wide range of wavelengths.

[0006] One method of achieving emission over a wide range of wavelengths may be to include multiple laser chips in the system, wherein some or all of the laser chips may be configured to emit light in different wavelength ranges. In some cases, the range of wavelengths may be wider than the inherent gain bandwidth of the laser stripes (e.g., quantum well epitaxial structure). Each laser chip may include laser stripes and may be grown and engineered separately on an epitaxial wafer. Multiple laser chips may jointly create a system capable of emitting different wavelengths. In some cases, growing laser chips on separate epitaxial wafers may increase the size, cost, and complexity of the system. One method of reducing the complexity and number of epitaxial wafers included in the system may be to include multiple laser stripes on the laser chip, wherein some or all of the laser stripes may emit light of different wavelengths. One method of including multiple laser stripes of different wavelengths within a range wider than the inherent bandwidth of the laser chip may be to utilize a hybrid process on the same epitaxial wafer. Summary of the invention

[0007] A laser chip including a plurality of stripes is described herein. The laser stripes may be grown using an initial optical gain profile, and their optical gain profile may be offset using a mixing process. In this way, a plurality of laser stripes may be formed from the same epitaxial wafer on the same laser chip, wherein at least one laser stripe may have an optical gain profile offset relative to another laser stripe. For example, each laser stripe may have an optical gain profile offset relative to its adjacent laser stripes, so that each laser stripe may emit light having a different wavelength range. The laser chip may emit light over a wide wavelength range. Examples of the present disclosure also include different regions of a given laser stripe having different amounts of mixing. For example, the laser stripe may have a mixed facet, wherein the facet may be positioned adjacent to a sub-region of an active region having a higher transition energy than a gain region (e.g., positioned between the facets). In some cases, the mixed facet may be used to minimize the possibility of changing the integrity of the laser facet. As another example, the laser stripe may have a mixed lateral region positioned adjacent to an active region (e.g., along a ridge waveguide). The mixed lateral region may be separated from the active region and may have a different amount of mixing than the active region. In some cases, hybrid lateral regions may be used to minimize optical losses and / or for potential energy increase in carrier confinement. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Example performance band diagrams of quantum well (QW) and quantum well intermixed (QWI) lasers according to examples of the present disclosure are shown.

[0009] Figure 2A A top view of a plurality of laser stripes included in an exemplary laser chip according to examples of the present disclosure is shown.

[0010] Figure 2B The example according to the present disclosure corresponds to Figure 2A Electronic band structure of multiple laser stripes.

[0011] Figure 2C The example according to the present disclosure corresponds to Figure 2A An exemplary gain profile of multiple laser stripes.

[0012] Figure 3A An exemplary fabrication process for forming a laser chip according to examples of the present disclosure is shown.

[0013] Figure 3B A cross-sectional view of an exemplary epitaxial wafer according to examples of the present disclosure is shown.

[0014] Figure 3C A cross-sectional view of an exemplary epitaxial wafer after etching a corresponding target number of layers according to examples of the present disclosure is shown.

[0015] Figure 3D A cross-sectional view of an exemplary epitaxial wafer after mixing and after growth of one or more cladding layers according to examples of the present disclosure is shown.

[0016] Figure 4 A top view of multiple laser stripes included in an exemplary laser chip having hybrid laser facets according to examples of the present disclosure is shown.

[0017] Figure 5A A top view of an exemplary laser chip including a reduced size top electrode according to examples of the present disclosure is shown.

[0018] Figure 5B A top view of an exemplary laser chip including at least two laser stripes with different electrode arrangements according to examples of the present disclosure is shown.

[0019] Fig. 6A Cross-sectional views of exemplary laser stripes and corresponding lateral regions are shown according to examples of the present disclosure.

[0020] Figure 6B Shown is a top view of an exemplary laser chip having a hybrid lateral region according to examples of the present disclosure.

[0021] Figure 7 A top view of an exemplary laser chip including a laser stripe configured to have both hybrid facets and hybrid lateral regions according to examples of the present disclosure is shown.

[0022] Fig. 8A A top view of an exemplary laser chip including a laser stripe with different mixing regions is shown, where the regions can be based on the shape of a gain profile according to examples of the present disclosure.

[0023] Figure 8B A top view of an exemplary laser chip including a laser stripe having multiple regions with different degrees of mixing according to examples of the present disclosure is shown.

[0024] Figure 8C A laser stripe configured with hybrid faceting and shaped interfaces is shown. DETAILED DESCRIPTION

[0025] In the following description of the examples, reference will be made to the accompanying drawings, in which specific examples that may be implemented are shown by way of illustration. It should be understood that other examples may be used and structural changes may be made without departing from the scope of the various examples.

[0026] Various techniques and process flow steps will now be described in detail with reference to the examples shown in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects and / or features described or mentioned therein. However, it is apparent to those skilled in the art that one or more aspects and / or features described or referenced herein may be implemented without some or all of these specific details. In other cases, well-known process steps and / or structures are not described in detail so as not to obscure some of the aspects and / or features described or referenced herein.

[0027] Moreover, although process steps or method steps may be described in a sequential order, such processes and methods may be configured to work in any suitable order. In other words, any sequence or order of steps that may be described in the present disclosure does not in itself indicate that the steps need to be performed in that order. In addition, although described or implied as occurring non-simultaneously (e.g., because one step is described after other steps), some steps may be performed simultaneously. In addition, the illustration of a process in the accompanying drawings by means of its description does not imply that the process shown excludes other variations and modifications thereof, does not imply that any of the processes shown or its steps must be one or more examples in the examples, and does not imply that the process shown is preferred.

[0028] Semiconductor lasers can be used in many applications such as trace gas detection, environmental monitoring, biomedical diagnostics, telecommunications, and industrial process control. Some applications can benefit from systems that can emit light over a wide range of wavelengths.

[0029] One method of achieving emission over a wide range of wavelengths may be to include multiple laser chips in the system, wherein some or all of the laser chips may be configured to emit light in different wavelength ranges. In some cases, the range of wavelengths may be wider than the inherent gain bandwidth of the laser stripes (e.g., quantum well epitaxial structure). Each laser chip may include laser stripes and may be grown and engineered separately on an epitaxial wafer. Multiple laser chips may jointly create a system capable of emitting different wavelengths. In some cases, growing laser chips on separate epitaxial wafers may increase the size, cost, and complexity of the system. One method of reducing the complexity and number of epitaxial wafers included in the system may be to include multiple laser stripes on the laser chip, wherein some or all of the laser stripes may emit light of different wavelengths. One method of including multiple laser stripes of different wavelengths within a range wider than the inherent bandwidth of the laser chip may be to utilize a hybrid process on the same epitaxial wafer.

[0030] The present disclosure relates to a laser chip including a plurality of stripes. The laser stripes may be grown using one or more materials having initial optical properties (e.g., optical gain distribution), and their optical properties may be altered (e.g., optical gain distribution may be offset) using a hybrid process that changes the material properties. In this way, multiple laser stripes may be formed on the same laser chip from the same epitaxial wafer, wherein the laser stripes have a common material. The hybrid process may change the material properties of at least one laser stripe so that its optical gain distribution is offset relative to the optical gain distribution of another laser stripe on the same epitaxial wafer. The hybrid process may be used to form different regions along the active region of the laser stripe with different transition energies and electronic band structures. For example, the laser stripe may have hybrid facets, wherein the facets may be positioned adjacent to a sub-region along the active region and may have a higher transition energy than a gain region (e.g., positioned between the facets). In some cases, the hybrid facets may be used to minimize the amount of optical absorption at the facets. Minimizing the amount of optical absorption may reduce the likelihood of altering the integrity of the laser facets (e.g., damaging or compromising the ability of the laser stripe to generate and emit light). As another example, the laser stripe may have a hybrid lateral region positioned adjacent to the active region. The hybrid lateral region may be separate from the active region and may have a different amount of hybridization than the active region. In some examples, the active region of the laser stripe may include different regions with different amounts of hybridization. In some cases, the hybrid lateral region may be used to minimize optical losses and / or increase potential energy for carrier limiting.

[0031] Representative applications of the methods and apparatuses according to the present disclosure are described in this section. These examples are provided only to add context and aid in understanding the examples. Therefore, it will be apparent to those skilled in the art that the examples may be practiced without some or all of the specific details. Other applications are possible, so that the following examples should not be considered limiting.

[0032] Semiconductor lasers can have many uses in portable or small electronic devices. Some applications can benefit from a system that can emit light over a wide range of wavelengths of interest. One way to achieve emission over a wide range of wavelengths while reducing system complexity can be to include multiple laser stripes on a laser chip, where one or more laser stripes can be configured to emit light of different wavelengths. Although each laser stripe can be grown and engineered separately on a different epitaxial wafer, some applications can benefit from a less complex system with a reduced number of epitaxial wafers.

[0033] One type of suitable semiconductor laser may be a quantum well (QW) laser. A QW laser may include a narrow bandgap material sandwiched between layers including a material with a larger bandgap energy. The difference in bandgap energy may create a quantum well for confining electrons and holes. Figure 1An example energy band diagram of a QW and quantum well hybrid (QWI) laser according to an example of the present disclosure is shown. The QW laser may have an electronic band structure 114 including a transition energy 116. Since the emission wavelength of a given laser may correspond to its transition energy, engineering the confinement potential of the quantum well may change the emission wavelength of the laser.

[0034] One approach to reducing the complexity and number of epitaxial wafers included in the system may be to utilize a hybrid process to generate multiple laser stripes from the same epitaxial wafer. The hybrid process may be a bandgap engineering technique where disorder may be introduced into the lattice structure to change the shape of the electronic band structure of the laser to an electronic band structure 124, such as Figure 1 This process can allow different atoms in the quantum well structure to intermix with each other. Exemplary processes may include, but are not limited to, ion implantation of uncharged species and defect diffusion from the semiconductor dielectric interface.

[0035] As shown, the mixing process can simultaneously cause a change in the shape of the electronic band structure and a change in the transition energy of the laser from transition energy 116 to transition energy 126. The larger transition energy 126 can cause the laser to emit light of a shorter wavelength. In this way, the laser stripe can be grown using an initial optical gain distribution, and its optical gain distribution can be shifted by using the mixing process.

[0036] This relationship between mixing and optical gain profile shift can be exploited to generate multiple laser stripes on the same epitaxial wafer with different emission wavelengths. Figure 2A shows a top view of a plurality of laser stripes included in an exemplary laser chip, and Figure 2B 3 shows a corresponding electronic band structure according to an example of the present disclosure. Laser chip 201 may include multiple laser stripes 202. In some examples, at least one laser stripe (e.g., laser stripe 202A) may not be exposed to the mixing process. Therefore, laser stripe 202A may have the same band structure 224 as the grown epitaxial wafer (e.g., epitaxial wafer 300 shown in FIG. 3). Laser stripe 202A may emit light 228A (e.g., corresponding to transition energy 206A) using transition energy 206A. Figure 2C 2A). In other cases, all laser stripes may be exposed to the mixing process. Thus, the laser stripes (eg, including laser stripe 202A) may have a different band structure than the epitaxial wafer on which it was grown.

[0037] Laser stripe 202B may be an adjacent (e.g., neighboring) laser stripe relative to laser stripe 202A (and / or laser stripe 202C) and may be exposed to the mixing process. Laser stripe 202B may have a band structure 224B that may be different from band structure 224A due to the mixing process, such as Figure 2B Laser stripe 202B may utilize transition energy 206B to emit light 228B (e.g., corresponding to Figure 2C 208B), laser stripe 202C may utilize transition energy 206C to emit light 228C (e.g., corresponding to Figure 2C 208C), and the laser stripe 202D can emit light 228D (e.g., corresponding to the transition energy 206D) using the transition energy 206D. Figure 2C Optical gain distribution 208D) is shown.

[0038] One or more laser stripes (e.g., laser stripe 202C and laser stripe 202D) may have their electronic band structure changed and their transition energy and emission wavelength shifted relative to one or more other (e.g., adjacent) laser stripes. In some cases, the direction of the shift may differ between adjacent laser stripes (e.g., a shift to a shorter wavelength relative to one adjacent laser stripe and a shift to a longer wavelength relative to another adjacent laser stripe). For example, laser stripe 202C may have two adjacent laser stripes: laser stripe 202B and laser stripe 202D. Laser stripe 202C may include an optical gain profile 208C that may have a greater wavelength than the optical gain profile 208D of another laser stripe 202D ( Figure 2C The optical gain profile 208C may also be shifted to a higher energy relative to the optical gain profile 208B of its other adjacent laser stripes 202B.

[0039] In some examples, as the position of the laser stripes on the epitaxial wafer increases relative to the edge of the epitaxial wafer, the offset may also increase. That is, the distance between the laser stripes may correspond to the amount of optical gain distribution offset. For example, laser stripe 202D may be located farther from laser stripe 202A than laser stripe 202C. The offset of optical gain distribution 208D from optical gain distribution 208A may be greater than the offset of optical gain distribution 208C from the same optical gain distribution 208A. In other examples, the offset of the optical gain distributions of different laser stripes may have different (e.g., different than a gradient increase) patterns, such as each other laser stripe may have an offset optical gain distribution.

[0040] One or more laser stripes 202 on the same epitaxial wafer may include the same type of material. For example, each laser stripe 202 may include alternating layers of InGaAs and InP. The laser stripes may include one or more wavelength band methods, including but not limited to DFB lasers, DBR lasers, tunable lasers, and Fabry-Perot lasers. In this way, a single epitaxial wafer (discussed below) may be grown for the laser chip 201. One or more (e.g., each) laser stripes 202 may be configured to have a different transition energy from one or more other laser stripes 202 located on the same laser chip 201 by using a hybrid process. For example, laser stripe 202A may be configured to have transition energy 206A, and laser stripe 202B may be configured to have transition energy 206B. Both laser stripes may be grown from the same epitaxial wafer, but transition energy 206A and transition energy 206B may be different.

[0041] Although the figures show a laser chip including four laser stripes with four different transition energies, examples of the present disclosure may include any number of laser stripes and any number of transition energies. In addition, examples of the present disclosure are not limited to adjacent laser stripes with different optical gain profiles, but may also include one or more laser stripes that may have the same optical gain profile as its adjacent laser stripes.

[0042] In some examples, the focusing of transition energy on the same epitaxial wafer can produce a continuous range of wavelengths. Figure 2C An exemplary optical gain profile corresponding to multiple laser stripes on the same epitaxial wafer according to an example of the present disclosure is shown. In some examples, each laser stripe 202 can have a different transition energy than other laser stripes 202 on the same epitaxial wafer 200, thereby producing a laser chip capable of emitting in multiple wavelength ranges with a reduced number of epitaxial wafers and reduced complexity.

[0043] In some examples, two or more (e.g., adjacent) laser stripes may include portions of overlapping (e.g., one or more wavelengths of the same) gain distributions. For example, laser stripe 202A and laser stripe 202B may be adjacent laser stripes (e.g., laser stripes positioned adjacent to each other on a laser epitaxial). Laser stripe 202A may include optical gain distribution 208A, and laser stripe 202B may include optical gain distribution 208B, wherein optical gain distribution 208A and optical gain distribution 208B may include adjacent or overlapping wavelength ranges. If extended across multiple laser stripes, the system may be configured to emit light over a wide range of wavelengths, wherein the optical gain of at least two laser stripes may allow the system to emit light at any given wavelength within the wavelength range.

[0044] In some examples, shifting the optical gain profile of another (e.g., adjacent) laser stripe may include shifting each laser stripe to a shorter wavelength (i.e., a larger transition energy) using a hybrid process. For example, laser light emitted at 680 nm may have a transition energy of 1.8 eV. The emission wavelength of an adjacent laser stripe may be shifted to a shorter wavelength (e.g., 610 nm) and a larger transition energy (e.g., 2.0 eV) using a hybrid process.

[0045] Figure 3A An exemplary fabrication process for forming a laser chip according to examples of the present disclosure is shown. Figure 3B-Figure 3D 2 shows a cross-sectional view of an exemplary laser chip at different steps in a manufacturing process according to an example of the present disclosure. Process 350 begins by growing a plurality of QW laser layers to form an epitaxial wafer (step 352 of process 350). An epitaxial wafer (e.g., epitaxial wafer 300) may be engineered to satisfy one or more laser stripes (e.g., Figure 2B The growth may include growing one or more QW layers 324 and one or more layers 328, such as Figure 3B The one or more layers 328 may include any layer included in the laser structure.

[0046] One or more photolithography steps may be used to define different regions on the epitaxial wafer (step 354 of process 350). The etching process may include multiple etching steps. Each etching step may remove a target number of layers 328 from one or more regions 332 (step 356 of process 350). For example, the etching process may remove five layers 328 from region 332D (step 357 of process 350). Figure 3C ). The number of layers 328 may be different for different regions 332. For another example, the etching process may remove one layer 328 from region 332B which is different from region 332D. Figure 3C ). In some examples, the etching process may include alternating between different selective etching steps, where one or more selective etchings may have a higher preferential etching of one or more layers 328 than other layers 328. The number of layers 328 within a given area 332 may be used, at least in part, to control the specific portion of the epitaxial wafer that is subject to the mixing process. For example, layer 328 may reduce the amount of mixing (e.g., dopant diffusion). In some cases, one or more laser stripes may be unexposed laser stripes, which may not be affected by the mixing process, but may be masked when other laser stripes are mixed (e.g., layer 328 may prevent dopant diffusion).

[0047] In order to remove a different amount of layer 328 in one region (e.g., region 332B) relative to another region (e.g., region 332D), one or more photolithography steps may be included between the etching steps. For example, a photolithography layer (e.g., photoresist) (not shown) may be deposited over regions 332A-332C, leaving region 332D exposed so that an etching process may remove layer 328 from region 332D, as shown. Figure 3C As shown. After the etching process, the photoresist layer can be removed. Another photoresist layer can be deposited on one or more different regions (e.g., region 332A-region 332B). Layer 328 can be removed from at least one unexposed region (e.g., region 332C). The etching process can also remove layer 328 from at least another unexposed region (e.g., region 332D).

[0048] The etching process may continue until a portion or all of region 332 includes a corresponding target amount of layer 328, such as Figure 3C As shown. The target amount may be based on the amount of mixing. That is, different regions 332 may include different total thicknesses of layers 328. For example, a greater number of layers 328 may be etched from region 332D relative to region 332B. In some cases, a smaller number of layers 328 in region 332D may allow for a greater amount of mixing in region 332D. A greater amount of mixing may increase the degree of disorder introduced into the epitaxial wafer at region 332D, and the transition energy of region 332D may be shifted by a greater amount than one or more other regions (e.g., regions 332A-332C).

[0049] One or more nominally undoped layers may be deposited over at least the etched regions (step 358 of process 350). One or more doped layers may include one or more impurities. Epitaxial wafer 300 may be exposed to a thermal process (e.g., rapid thermal annealing) such that impurities from one or more doped layers may form a disorder in the lattice structure of QW layer 324 (step 360 of process 350). One or more doped layers and layer 328 may be removed (step 362 of process 350). One or more cladding layers 338 may be grown over the etched regions (step 364 of process 350), as shown. Figure 3D A plurality of electrodes (not shown) may be deposited (step 366 of process 350).

[0050] The QWI process described above can be used to change the amount of optical absorption in certain additional areas of the laser. An exemplary area of ​​the laser that can benefit from changes in optical absorption can be the laser facets. For example, when the laser power density is high, the laser facets can absorb too much energy. A large amount of absorption can cause heating at the laser facets, which can affect the integrity of the laser facets. In some cases, the possibility of COD can be increased due to hanging bonds and point defects generated by forming (e.g., cutting and / or etching) the laser facets. In order to reduce optical absorption so that the possibility of COD is reduced, the laser facets can be constructed with a larger transition energy using a hybrid process. The facets can become more transparent to light, thereby reducing the heat caused by absorption and increasing the life of the laser.

[0051] Figure 4 A top view of multiple laser stripes included in an exemplary laser chip with hybrid laser facets according to an example of the present disclosure is shown. Laser chip 401 may include multiple laser stripes 402, which may include one or more characteristics and / or functions similar to the multiple laser stripes 202 described above. One or more laser stripes 402 may have a waveguide including different sub-regions 403 and 405. For example, laser stripe 402A may include sub-region 403A and sub-region 405A. As used throughout this disclosure, a "sub-region" is a region along the active region of a laser (e.g., along a growth plane). Sub-region 403A may have a band structure (e.g., Figure 2B The sub-region 405A may have another energy band structure (e.g., Figure 2B 224B). In some examples, subregions 405 may be located at facets of corresponding laser stripes 402, and subregions 403 (e.g., gain regions) of the laser stripes may be located between subregions 405. That is, subregions of a given laser that are closer to a laser facet may have greater transition energy than subregions of the given laser that are located in a region that coincides with the maximum gain of the laser.

[0052] In some examples, a subregion (e.g., subregion 405A) of a laser stripe (e.g., laser stripe 402A) can be configured to have the same band structure as another subregion (e.g., subregion 403B) of another laser stripe (e.g., an adjacent laser stripe, such as laser stripe 402B). Examples of the present disclosure may include all laser stripes with hybrid facets except one laser stripe (e.g., laser stripe 402D). The laser stripe (e.g., laser stripe 402D) without hybrid facets may have, for example, the shortest emission wavelength relative to other laser stripes 402.

[0053] The process for mixing sub-regions corresponding to laser facets may include patterning a photolithography layer (not shown) and performing an etching process so that during the mixing process, the number of layers 228 in a sub-region (e.g., sub-region 405A) is the same as the number of layers in a sub-region (e.g., sub-region 403B) of another laser stripe (e.g., laser stripe 402B). A sub-region of one laser stripe may experience the same degree of mixing as another sub-region of another laser stripe. The other laser stripe may be any laser stripe on the same epitaxial chip, including but not limited to adjacent laser stripes.

[0054] Additionally or alternatively, examples of the present disclosure may include a top electrode having a smaller size than the ridge waveguide to minimize the likelihood of COD. Figure 5A A top view of an exemplary laser chip including a reduced size top electrode according to an example of the present disclosure is shown. The laser chip 501 may include a plurality of laser stripes 502, which may include one or more characteristics and / or functions similar to the plurality of laser stripes 202 and / or the laser stripes 402 described above. The laser stripe 502A may include a sub-region 507A and a sub-region 509A. The sub-region 509A may be located at or near the laser facet, and the sub-region 507A may be located at a gain region (e.g., a region coinciding with the maximum gain of the laser). The top electrode 544 (i.e., the electrode positioned closer to the ridge waveguide) of one or more laser stripes 502 may be configured such that its length L1 (i.e., in the longitudinal direction) is less than the length L2 of the laser stripe 502. In some examples, the length L1 of the top electrode 544 may be the same as the length of the sub-region 507A. In this way, fewer charge carriers may be injected at a position adjacent to one or more laser facets (e.g., the sub-region 509A), which may reduce the amount of optical absorption at the laser facets. Since the gain profile along the laser stripe (e.g., including the active region) has a maximum gain away from the laser facets (e.g., at the center of the laser), pumping the facet regions may not improve the performance of the laser stripes due to their light transmittance. Likewise, reducing the amount of pumping at the facet regions may reduce the likelihood of COD without causing significant or any detriment to laser performance. Although the figures show all four laser stripes as including a reduced size top electrode, examples of the present disclosure may also include a reduced size top electrode on less than all laser stripes 502. For example, one laser stripe may include a reduced size top electrode while another laser stripe may not.

[0055] Additionally or alternatively, examples of the present disclosure may include laser stripes having different lengths for a reduced size top electrode. Figure 5BA top view of an exemplary laser chip including at least two laser stripes with different electrode arrangements according to an example of the present disclosure is shown. In some cases, the electrode arrangement may be such that the lateral spacing from the edge of the electrode to the laser facet (e.g., related to the length of the top electrode) may be based on the transition energy of the laser stripe (e.g., and / or the transition energy of the gain region of the laser stripe). For example, laser stripe 502D may have a greater transition energy than laser stripe 502A. Due to the greater transition energy, the facet of laser stripe 502D may be more susceptible to COD due to higher optical absorption. In some examples, a laser stripe with a greater transition energy (e.g., laser stripe 502D) may include a top electrode 554B having a longer length (e.g., length L2) than a top electrode 554A of a laser stripe with a smaller transition energy (e.g., laser stripe 502A having a top electrode with a shorter length L1). In some examples, all laser stripes except one laser stripe (e.g., laser stripe 502D) may have the same electrode arrangement. In some examples, the length of the top electrode may vary gradually (e.g., may be based on the transition energy), as shown. Examples of the present disclosure also include being configured to have both mixed facets (e.g., Figure 4 ) and reduced spacing top electrodes (such as Figure 5A One or more laser stripes) as discussed in the context of .

[0056] In some cases, one or more regions of the laser may be associated with higher losses. Fig. 6A A cross-sectional view of an exemplary laser stripe and corresponding lateral regions according to an example of the present disclosure is shown. The laser stripe 602A may include a ridge waveguide 643A and a top electrode 644A electrically coupled to the ridge waveguide 643A. The ridge waveguide 643A may be located between the lateral regions 611A. In some examples, the lateral region 611A may include a QW layer 624 and may absorb light, which may result in an increase in loss and a decrease in laser quantum efficiency.

[0057] Examples of the present disclosure may include using a hybrid process for one or more regions surrounding a ridge waveguide (eg, ridge waveguide 643 ) and / or an active region (eg, lateral region 611 ). Figure 6B A top view of an exemplary laser chip with hybrid lateral regions according to an example of the present disclosure is shown. Laser chip 601 may include multiple laser stripes 602, which may include one or more characteristics and / or functions similar to the multiple laser stripes 202, laser stripes 402, and / or laser stripes 502 described above. One or more laser stripes (e.g., laser stripe 602A) may have lateral regions (e.g., lateral regions 611A) positioned adjacent to its waveguide (e.g., ridge waveguide 643A) and / or active region. Ridge waveguide 643A may have a band structure (e.g., Figure 2BThe band structure 224A shown in FIG. 2 ), and one or more lateral regions 611A may have a different band structure (e.g., Figure 2B Band structure 224B shown). In some examples, a lateral region (e.g., lateral region 611A) can be configured to have the same band structure as a ridge waveguide (e.g., ridge waveguide 643B) of another laser stripe (e.g., its adjacent laser stripe, such as laser stripe 602B). Examples of the present disclosure may include all laser stripes with hybrid lateral regions except one laser stripe (e.g., laser stripe 602D). The laser stripe without hybrid lateral regions (e.g., laser stripe 602D) may have, for example, the shortest emission wavelength relative to other laser stripes 602. In some examples, the system may operate the laser stripes without hybrid lateral regions differently (e.g., at a higher injection current) to compensate for the difference in loss (e.g., higher) (relative to the laser stripes with hybrid lateral regions).

[0058] The process for intermixing the lateral regions may include patterning a photolithography layer (not shown) and performing an etching process so that the layers (eg, Figure 3B The number of layers 328 shown is the same as the ridge waveguides (eg, ridge waveguide 643A) of an adjacent laser stripe (eg, laser stripe 602B). A lateral region of one laser stripe may experience the same degree of mixing as the ridge waveguides of another laser stripe.

[0059] Examples of the present disclosure also include one or more laser stripes configured to have a combination of one or more of the above examples: hybrid facets (such as in Figure 4 ), the top electrode with reduced spacing (as discussed in the context of Figure 5A-Figure 5B ), and mixed lateral regions (as discussed in the context of Figure 6A-6B For example, Figure 7 A top view of an exemplary laser chip according to an example of the present disclosure is shown, the exemplary laser chip including laser stripes configured to have both hybrid facets and hybrid lateral regions. Laser chip 701 may include multiple laser stripes 702, which may include one or more characteristics and / or functions similar to the multiple laser stripes 202, laser stripes 402, laser stripes 502, and / or laser stripes 602 described above. One or more laser stripes 702 may have a waveguide including different sub-regions 703 and 705. For example, laser stripe 702A may include sub-region 703A and sub-region 705A. Sub-region 703A may have a band structure (e.g., Figure 2B The band structure 224A shown in FIG. 2 ), and the sub-region 705A may have a different band structure (e.g., Figure 2B224B). In some examples, subregions 705 may be located at facets of respective laser stripes 702, wherein subregions 703 (e.g., gain regions) of the laser stripes may be located between subregions 705. In some examples, a subregion (e.g., subregion 705A) of a laser stripe (e.g., laser stripe 702A) may be configured to have the same band structure as a gain region (e.g., subregion 703B) of an adjacent laser stripe (e.g., laser stripe 702B). In some cases, subregion 703A may overlap with ridge waveguide 743A.

[0060] The ridge waveguide 743A may be located between the lateral regions 711A. The ridge waveguide 743A may have a band structure (eg, Figure 2B The band structure 224A shown in FIG. 2 ), and one or more lateral regions 711A may have a different band structure (e.g., Figure 2B 224B). In some examples, a lateral region (e.g., lateral region 711A) can be configured to have the same band structure as a ridge waveguide (e.g., ridge waveguide 743A) of an adjacent laser stripe (e.g., laser stripe 702B). In some examples, two or more of a sub-region 705 (e.g., a hybrid facet region) of a given laser, a lateral region 711 of the same laser, and a sub-region 703 (e.g., a gain region) of an adjacent laser can have the same band structure.

[0061] Examples of the present disclosure may include all laser stripes with mixed lateral regions except one laser stripe (e.g., laser stripe 702D). In addition or alternatively, the same (or different) laser stripes may not have mixed facet regions. In some cases, the lateral region 711 may laterally surround the ridge waveguide 743 (and / or active region), and the subregion 705 may longitudinally surround the ridge waveguide 743 (and / or active region). In addition or alternatively, the laser chip may include one or more laser stripes configured to have a top electrode of reduced size, as described above. The process for mixing the corresponding regions may include patterning the photolithography layer based on the different regions for mixing.

[0062] In some examples, different regions for mixing can be configured based on the shape of the gain profile of the laser stripe. Figure 8A-8C A top view of an exemplary laser chip including different regions for mixing based on the shape of a gain profile according to an example of the present disclosure is shown. For example, laser chip 801A may include laser stripe 802A. Laser stripe 802A may include multiple sub-regions along its active region, such as sub-region 803 and sub-region 813, as shown in FIG. Fig. 8ASubregion 803 and subregion 813 may be exposed to different degrees of mixing during the manufacturing process and may have different band structures. For example, subregion 803 may not be exposed to mixing and may have a band structure similar to Figure 2B Subregion 813 may be exposed to mixing, may have a greater transition energy than subregion 803, and / or may have a similar Figure 2B The band structure shown is band structure 224B. "Shaping" of the lateral mixing can help control the pattern of the laser stripes.

[0063] The location where sub-region 803 and sub-region 813 meet can result in an optical gain distribution that reflects laser stripe 802A (e.g., Figure 2C 802A). In some examples, the shape of the interface can complement the optical mode of laser stripe 802A. Since the gain near the facet (i.e., the gain tail) can be small (e.g., almost zero), the area near the pump facet can result in higher optical absorption. Laser stripe 802A can be configured so that sub-region 813 (e.g., a region located closer to the edge of the active region) has a different (e.g., higher) transition energy than sub-region 803.

[0064] Examples of the present disclosure may include a laser stripe configured to have multiple sub-regions with different mixing levels, such as Figure 8B As shown. Laser chip 801B may include laser stripe 802B. Laser stripe 802B may include sub-region 803, sub-region 813, and sub-region 815 along its active region. Sub-region 815 may be exposed to a greater amount of mixing than sub-region 813, and sub-region 813 may be exposed to a greater amount of mixing than sub-region 803. For example, sub-region 803 may have band structure 224A ( Figure 2B ), the sub-region 813 may have a band structure 224B ( Figure 2B ), and the sub-region 815 may have a band structure 224C ( Figure 2B ). That is, for a given laser stripe, the transition energy may increase closer to the edge of its active region. The interface between subregion 803 and subregion 813 and / or the interface between subregion 813 and subregion 815 may have a shape based on the gain distribution of laser stripe 802B. In some examples, one or more subregions (e.g., subregion 813 and / or subregion 815) may not be a pumping region, while other subregions (e.g., subregion 803) may be a pumping region.

[0065] Examples of the present disclosure also include one or more laser stripes configured to have a combination of one or more of the above examples: hybrid facets (such as in Figure 4 ), the top electrode with reduced spacing (as discussed in the context of Figure 5A-Figure 5B ), mixed lateral regions (as discussed in the context of Figure 6A-6B ), with interfaces between sub-regions based on the shape of the gain distribution (as discussed in the context of Fig. 8A ) and various degrees of mixing of the same laser stripe (as discussed in the context of Figure 8B For example, Figure 8C A laser stripe configured to have hybrid facets (eg, at sub-region 809) and shaped interfaces (eg, at sub-region 803 and sub-region 813) is shown.

[0066] In some examples, the shape of the top electrode can be based on the gain distribution. In this way, pumping laser stripes in areas with little gain (e.g., facets) can prevent or reduce losses in areas with gain (e.g., longitudinal center). In some cases, the laser can be pumped unevenly throughout the active region.

[0067] The present invention discloses a laser chip. The laser chip may include: a plurality of laser stripes including at least one laser stripe, the at least one laser stripe including: one or more first sub-regions of an active region along the at least one laser stripe, the one or more first sub-regions including a first transition energy, and one or more second sub-regions along the active region, the one or more second sub-regions including a second transition energy and a second doping amount, wherein the second transition energy is different from the first transition energy, wherein the one or more first sub-regions and the one or more second sub-regions include the same epitaxial wafer. In addition or alternatively, in some examples, the laser chip further includes: an unexposed laser stripe, the unexposed laser stripe including a third transition energy, wherein the third transition energy is the same as the transition energy of the epitaxial wafer. In addition or alternatively, in some examples, the one or more first sub-regions are positioned adjacent to a facet of the at least one laser stripe, and the one or more second sub-regions are positioned adjacent to a gain region of the at least one laser stripe. In addition or alternatively, in some examples, the plurality of laser stripes include another laser stripe, wherein the second transition energy of the one or more second sub-regions of the another laser stripe is the same as the first transition energy of the one or more first sub-regions of the at least one laser stripe. Additionally or alternatively, in some examples, the first transition energy of the one or more first sub-regions is greater than the second transition energy of the one or more second sub-regions. Additionally or alternatively, in some examples, the laser chip further comprises: one or more electrodes disposed along the active regions of the plurality of laser stripes, wherein for at least one laser stripe: the electrode of at least one laser stripe has a first length along the active region of the at least one laser stripe, and the active region of the at least one laser stripe has a second length, wherein the first length is less than the second length. Additionally or alternatively, in some examples, the plurality of laser stripes comprises another laser stripe, wherein the electrode of the other laser stripe has a third length along the active region of the other laser stripe, the third length being different from the first length and the second length. Additionally or alternatively, in some examples, the third length is longer than the first length, and wherein the second transition energy of the other laser is greater than the second transition energy of the at least one laser stripe. Additionally or alternatively, in some examples, the one or more first sub-regions of the at least one laser stripe comprises the active region of the at least one laser stripe, and wherein the one or more second sub-regions of the at least one laser stripe comprises a lateral region positioned adjacent to the active region of the at least one laser stripe. Additionally or alternatively, in some examples, the plurality of laser stripes includes another laser stripe, wherein a second transition energy of one or more second subregions of the another laser stripe is the same as a first transition energy of one or more first subregions of the at least one laser stripe.Additionally or alternatively, in some examples, the second transition energy of one or more second subregions of at least one laser stripe is greater than the first transition energy of one or more first subregions of at least one laser stripe. Additionally or alternatively, in some examples, the one or more first subregions and the one or more second subregions of at least one laser stripe are both located on the active region of at least one laser stripe. Additionally or alternatively, in some examples, the first transition energy of one or more first subregions is greater than the second transition energy of one or more second subregions, and wherein the one or more first subregions are positioned closer to the edge of the active region of at least one laser stripe than the one or more second subregions. Additionally or alternatively, in some examples, the plurality of laser stripes include another laser stripe, and wherein the optical gain profile of the another laser stripe is offset relative to the optical gain profile of at least one laser stripe. Additionally or alternatively, in some examples, the one or more first subregions and the one or more second subregions include different amounts of mixing.

[0068] The present invention discloses a method for manufacturing a laser chip. The method may include: forming a plurality of laser stripes, wherein forming the plurality of laser stripes includes: growing an epitaxial wafer; mixing at least one laser stripe, wherein mixing includes: mixing one or more first sub-regions along the active region of at least one laser stripe to a first amount; mixing one or more second sub-regions along the active region of at least one laser stripe to a second amount, the second amount being different from the first amount. In addition or alternatively, in some examples, growing the epitaxial wafer includes growing a plurality of layers, and the method further includes: removing one or more of the plurality of layers from one or more first sub-regions of at least one laser stripe, wherein the one or more first sub-regions are positioned adjacent to a facet of the at least one laser stripe; and removing one or more of the plurality of layers from one or more second sub-regions of at least one laser stripe, wherein the one or more second sub-regions are positioned adjacent to a gain region of the at least one laser stripe. Additionally or alternatively, in some examples, growing the epitaxial wafer includes growing a plurality of layers, the method further comprising: removing one or more of the plurality of layers from one or more first sub-regions of at least one laser stripe, wherein the one or more first sub-regions include an active region of the at least one laser stripe; and removing one or more of the plurality of layers from one or more second sub-regions of the at least one laser stripe, wherein the one or more second sub-regions are lateral regions positioned adjacent to the active region of the at least one laser stripe. Additionally or alternatively, in some examples, growing the epitaxial wafer includes growing a plurality of layers, the method further comprising: removing one or more of the plurality of layers from one or more first sub-regions of the at least one laser stripe; and removing one or more of the plurality of layers from one or more second sub-regions of the at least one laser stripe, wherein the one or more first sub-regions are positioned closer to an edge of the active region of the at least one laser stripe than the one or more second sub-regions. Additionally or alternatively, in some examples, forming the plurality of laser stripes further comprises: mixing another laser stripe, wherein the mixing comprises: mixing the one or more second sub-regions to a first amount along the active region of the another laser stripe. Additionally or alternatively, in some examples, growing the epitaxial wafer includes growing a plurality of layers, the method further comprising: masking unexposed laser stripes with the grown plurality of layers while at least one laser stripe is mixed.

[0069] Although the disclosed examples have been fully described with reference to the accompanying drawings, it should be noted that various changes and modifications will become apparent to those skilled in the art. It should be understood that such changes and modifications are considered to be included within the scope of the disclosed examples as defined by the appended claims.

Claims

1. A laser chip, comprising: A first laser stripe, wherein the first laser stripe comprises: a first sub-region of the first laser stripe; and a second sub-region of the first laser stripe, wherein the energy band structure of the first sub-region is different from the energy band structure of the second sub-region; and A second laser stripe, wherein the second laser stripe comprises: a third sub-region of the active area along the second laser stripe; and a fourth sub-region of the active area along the second laser stripe, wherein the energy band structure of the third sub-region is different from the energy band structure of the fourth sub-region; At least two of the first sub-region, the second sub-region, the third sub-region or the fourth sub-region are configured with the same energy band structure, wherein: The first laser stripe comprises: a first facet at a first end of the first laser stripe; a second facet at a second end of the first laser stripe; The first sub-area includes: a first band structure located at the first facet and the second facet; and The second sub-region is positioned between the first facet and the second facet.

2. The laser chip according to claim 1, wherein: The second laser stripe comprises: a third facet at a first end of the second laser stripe; a fourth facet at a second end of the second laser stripe; The third sub-area includes: a third band structure located at the third facet and the fourth facet; and The fourth sub-region is positioned between the third facet and the fourth facet; The fourth sub-region has the same energy band structure as the first sub-region. 3 . The laser chip according to claim 1 , wherein the second sub-region is located in a region that coincides with a maximum gain of the first laser stripe.

4. The laser chip according to claim 1, wherein: The laser chip further includes a third laser stripe, and the third laser stripe includes: a fifth sub-region of the active area along the third laser stripe; and a sixth sub-region of the active area along the third laser stripe, The energy band structure of the fifth sub-region is different from the energy band structure of the sixth sub-region. 5 . The laser chip according to claim 4 , further comprising a fourth laser stripe, the fourth laser stripe comprising a region having the same energy band structure as the fifth sub-region of the third laser stripe. 6 . The laser chip according to claim 5 , wherein the sixth sub-region has the same energy band structure as the third sub-region. 7 . The laser chip according to claim 6 , wherein each laser stripe of the laser chip emits light at a different wavelength.

8. A laser chip, comprising: Epitaxial wafers; A first laser stripe on the epitaxial wafer, the first laser stripe comprising: a first facet at a first end of the first laser stripe and having a first band structure; a second facet at a second end of the first laser stripe and having the first energy band; a first sub-region located between the first facet and the second facet and having a second energy band structure; A second laser stripe on the epitaxial wafer, the second laser stripe comprising: a third facet at a first end of the second laser stripe and having a third band structure; a fourth facet at a second end of the second laser stripe and having the third energy band; a second sub-region located between the third facet and the fourth facet and having a fourth energy band structure, wherein: The first laser stripe emits light at a first wavelength; and The second laser stripe emits light at a second wavelength.

9. The laser chip according to claim 8, wherein: The first energy band structure is different from the second energy band structure; The third energy band structure is different from the fourth energy band structure; and The third energy band structure is the same as the first energy band structure.

10. The laser chip according to claim 8, wherein: The laser chip comprises: a third laser stripe of the epitaxial wafer; and a fourth laser stripe of the epitaxial wafer; The third laser stripe includes a third sub-region positioned between the fifth facet and the sixth facet; The fourth laser stripe includes a fourth sub-region positioned between the seventh facet and the eighth facet; The fifth facet and the sixth facet have a fifth energy band structure; and The third sub-region has a sixth energy band structure. 11 . The laser chip according to claim 10 , wherein the fourth sub-region has the same seventh energy band structure as that of the epitaxial wafer. 12 . The laser chip according to claim 11 , wherein the seventh facet and the eighth facet have the same seventh energy band structure as the epitaxial wafer.

13. The laser chip according to claim 10, wherein: The first laser stripe includes a first top electrode; and The first top electrode has the same length as the first sub-region.

14. The laser chip according to claim 13, wherein: The second laser stripe includes a second top electrode; and The second top electrode has a length greater than the second sub-region.

15. The laser chip according to claim 14, wherein: The third laser stripe includes a third top electrode; and The length of the third top electrode is the same as the total length of the third sub-region, the fifth facet, and the sixth facet.

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