Limiting features for laser mode forming and coupling with photonic silicon components

Abstract

Semiconductor laser structure made of a III-V semiconductor material, comprising: a laser core (12) formed from a III-V semiconductor material with a high refractive index and embedded in a dielectric matrix (14); wherein the dielectric matrix (14) is formed from a first III-V semiconductor material formed from a material having a lower refractive index than the laser core (12);wherein the dielectric matrix (14) is arranged in a vertical direction between a p-doped layer (18) and an n-doped layer (16), wherein the part of the dielectric matrix (14) that is adjacent to the n-doped layer (16) has an n-doped section (20) that is arranged laterally between p-doped sections (22, 24), and wherein the part of the dielectric matrix (14) that is adjacent to the p-doped layer (18) has a p-doped section (26) that is arranged laterally between n-doped sections (28, 30); and a plurality of side boundary features (40) formed in the dielectric matrix (14) and extending parallel to and along a length of the laser core (12), wherein the side boundary features (40) are formed laterally adjacent to the laser core (12), wherein the plurality of the side boundary features (40) comprise the III-V semiconductor material with a high refractive index.

Description

BackgroundThe present invention relates generally to photonic integrated circuits and, more particularly, to confinement features for mode shaping of III-V lasers and improved coupling with silicon (Si) photonic components.Silicon photonics is developing into a common data transmission solution for next generation data centers, high performance computers, and many new applications. Silicon-based photonic integrated circuits (PICs) promising low cost and high volume solutions for next generation high speed optical links that are energy efficient. While considerable advances have been made at both the component and system levels, on-chip integration of low cost and energy efficient laser sources (e.g., III-V semiconductor lasers) on a silicon-based PIC still presents a great challenge. For example, efficient coupling between III-V semiconductor lasers and photonic silicon waveguides remains a major problem due to the mismatch of the mode profile between III-V semiconductor lasers and photonic silicon waveguides.US 6 167 073 A discloses a semiconductor structure having an asymmetric optical waveguide structure consisting of a substrate, an active region and optical confinement and cladding layers.US 6 798 568 B1 describes a semiconductor optical amplifier with polarization independent amplification through a polarization matching layer formed over an active region with strained quantum films and etched to a thickness that repositions the optical signal within the active region.US 5 272 711 A mentions a high power semiconductor laser diode having a lateral antiresonant reflecting optical waveguide which generates a single mode laser beam having an aperture spot size of about 4 to 8 microns by reflecting the fundamental mode and exiting higher modes.SummaryThe present invention relates generally to photonic integrated circuits and, more particularly, to confinement features for mode shaping of III-V lasers and improved coupling with silicon (Si) photonic components. An illustrative laser structure described herein includes: a dielectric matrix formed of a first material; a laser source formed within the dielectric matrix and of a semiconductor material; and a plurality of side boundary features formed within the dielectric matrix and extending parallel to and along a length of the laser source, wherein the plurality of side boundary features are formed of the semiconductor material.Another illustrative laser structure described herein includes: a dielectric matrix formed of a first material; a laser source formed within the dielectric matrix and including a semiconductor material; and a plurality of vertical confinement features formed within the dielectric matrix and extending parallel to and along a length of the laser source, wherein the plurality of vertical confinement features include the semiconductor material.An illustrative laser system described herein comprises: a laser source; and a waveguide optically coupled to the laser source, wherein the laser source comprises: a dielectric matrix formed of a first material; a laser source formed within the dielectric matrix and comprising a semiconductor material; and a plurality of confinement features formed within the dielectric matrix and extending parallel to and along a length of the laser source, wherein the plurality of confinement features comprise the semiconductor material, wherein the plurality of confinement features are formed on a side and / or top and / or bottom of the laser source, and wherein the plurality of confinement features are configured to match a size and profile of a mode of the laser source to a mode of the waveguide.According to the invention, there is provided an apparatus according to claim 1, 8 or 15.Brief Description of the DrawingsThe invention will be understood with reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals designate like elements. FIG. 1 shows a cross-sectional view of a III-V semiconductor laser structure with symmetrically arranged side boundary features according to various embodiments of the invention. FIG. 2 is a plan view of the laser core and side boundary features of FIG. 1 according to various embodiments of the invention. FIG. 3 shows a cross-sectional view of another III-V semiconductor laser structure with side boundary features according to various embodiments of the invention. FIG. 4 is a plan view of the laser core and side boundary features of FIG. 3 according to various embodiments of the invention. FIG. 5 shows a cross-sectional view of another III-V semiconductor laser structure with side boundary features according to various embodiments of the invention. FIG. 6 is a plan view of the laser core and side boundary features of FIG. 5 according to various embodiments of the invention. FIG. 7 shows a cross-sectional view of another III-V semiconductor laser structure with side boundary features according to various embodiments of the invention. FIG. 8 is a plan view of the laser core and side boundary features of FIG. 7 according to various embodiments of the invention. FIG. 9 shows a cross-sectional view of another III-V semiconductor laser structure with side boundary features according to various embodiments of the invention. FIG. 10 is a plan view of the laser core and side boundary features of FIG. 9 according to various embodiments of the invention. FIG. 11 shows a cross-sectional view of another III-V semiconductor laser structure with side boundary features according to various embodiments of the invention. FIG. 12 shows a cross-sectional view of a III-V semiconductor laser structure with vertical confinement features according to various embodiments of the invention. FIG. 13 is a side perspective view of the laser core and vertical confinement features of FIG. 12 according to various embodiments of the invention. FIG. 14 shows a cross-sectional view of another III-V semiconductor laser structure with vertical confinement features according to various embodiments of the invention. FIG. 15 is a side perspective view of the laser core and vertical confinement features of FIG. 14 according to various embodiments of the invention. FIG. 16 shows a cross-sectional view of another III-V semiconductor laser structure with vertical confinement features according to various embodiments of the invention. FIG. 17 is a side perspective view of the laser core and vertical confinement features of FIG. 16 according to various embodiments of the invention. FIG. 18 shows a cross-sectional view of another III-V semiconductor laser structure with vertical confinement features according to various embodiments of the invention. FIG. 19 is a side perspective view of the laser core and vertical confinement features of FIG. 18 according to various embodiments of the invention. FIG. 20 shows a cross-sectional view of another III-V semiconductor laser structure with vertical confinement features according to various embodiments of the invention. FIG. 21 shows a cross-sectional view of the laser core and vertical confinement features of FIG. 20 according to various embodiments of the invention. FIGS. 22-28 show cross-sectional views of methods of fabricating a III-V semiconductor laser structure with side boundary features according to various embodiments of the invention. FIGS. 29-33 show cross-sectional views of methods of fabricating a III-V semiconductor laser structure having vertical confinement features according to various embodiments of the invention.Although the subject matter described herein may be variously modified and alternatively embodied, specific embodiments thereof are illustrated by way of example in the drawings and described herein in detail. The description of specific embodiments herein is not intended to limit the invention to the specific embodiments, but on the contrary, to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.Detailed DescriptionIn the following description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the present teachings may be practiced. The following description is for illustrative purposes only.The words and terms used herein are to be understood and interpreted as having a meaning that is consistent with the understanding of these words and terms by those skilled in the relevant art. A particular definition of a term or phrase, i.e., a definition that differs from the ordinary and customary meaning as understood by those skilled in the art, is not intended to be implied herein by the uniform use of a term or phrase. Where a term or formulation is intended to have a particular meaning, i.e., a meaning that is distinct from understanding by those skilled in the art, such particular definition is expressly set forth in the specification in a limiting manner that provides the particular definition for the term or formulation directly and indiscernibly.The present invention relates generally to III-V semiconductor lasers integrated with various configurations of side boundary features and / or vertical boundary features. The laser core (laser medium) and the confinement features may be formed of high refractive index III-V semiconductor materials and embedded in a metamaterial (e.g., a dielectric matrix) whose refractive index is lower than that of the laser core and the confinement features. The side confinement features and / or vertical confinement features may be formed in symmetric and / or asymmetric configurations depending on, for example, the geometry and mode shape of the waveguide to which the laser core is coupled (e.g., an inverse cone silicon (Si) waveguide). The side boundary features and / or vertical boundary features may be chosen to adjust the size and profile of the laser modes to reduce mode mismatch between III-V semiconductor lasers and waveguides, thus increasing coupling efficiency.Referring to FIG. 1, a cross-sectional view of a III-V semiconductor laser structure 10 (hereinafter III-V laser 10) is shown in accordance with embodiments. The III-V laser 10 may be shown to include a laser core 12 formed from a III-V semiconductor material having a high refractive index (e.g., a refractive index > 2.0) and embedded in a dielectric matrix 14 formed from a material having a lower refractive index than that of the laser core 12. In certain embodiments, the laser core 12 may be formed of a III-V semiconductor material such as Indiumgalliumarsenidphosphid (InGaAsP). Other suitable III-V semiconductor materials may also be used to form the laser core 12, e.g., InCaAs, InCaASN, GaAsSb, AlGaAs, or GaAs. The dielectric matrix 14 may be formed of doped indium phosphide (InP) or other suitable materials (e.g., InAs and InSb).The dielectric matrix 14 may be formed between n- and p-doped layers 16, 18 of InP or other suitable materials (e.g., InAs and InSb). The portion of the dielectric matrix 14 adjacent to the n-doped layer 16 of InP may include an n-doped portion 20 of InP formed between p-doped portions 22, 24 of InP. The portion of the dielectric matrix 14 adjacent to the p-doped layer 18 of InP may include a p-doped portion 26 of InP formed between n-doped portions 28, 30 of InP. n-doped dopants may include phosphorus (P), arsenic (As), and antimony (Sb), and p-doped dopants may include boron (B), indium (In), and gallium (Ga).According to embodiments, a set of one or more side boundary features 40 may be formed adjacent the laser core 12. As shown in FIG. 1, for example, a plurality of symmetrically disposed side boundary features 40 laterally adjacent the laser core 12 may be formed of InP in the p-doped portions 22, 24. According to embodiments, the side-limiting features 40 may be formed of the same high refractive index III-V semiconductor material as the laser core (e.g., InGaAsP). Other high refractive index III-V semiconductor materials such as InCaAs, InCaASN, GaAsSb, AlGaAs, or GaAs may also be used to form the side boundary features 40. In some embodiments, the laser core 12 and the side boundary features 40 may be formed from different III-V semiconductor materials. The plurality of symmetrically disposed side boundary features 40 formed in the p-doped portions 22, 24 of InP on each side of the laser core 12 may have the same pitch and duty cycle. The side boundary features 40 may be formed at the same time as the laser core 12 and may have the same height 40H, depending on the embodiment.According to embodiments, the side boundary features 40 (and other side boundary features 40 described below) may be configured to adjust the mode size and mode profile of the III-V laser 10 to reduce mode mismatch between the III-V laser 10 and a photonic integrated circuit waveguide. For example, as shown in FIG. 1, the side boundary features may be formed for use with an inversely tapered Si waveguide 52 of a Si-based photonic integrated circuit 50.A plan view of the side boundary features 40 and the laser core 12 of FIG. 1 is shown in FIG. 2. According to embodiments related to FIGS. 1 and 2, the side boundary features 40 on opposite sides of the laser core 12 may be symmetrically formed in the InP p-doped portions 22, 24. The laser core 12 may have a width 12W of about 1 μm to about 5 μm and a height 12H of about 50 nm to about 300 nm. The side boundary features 40 may have a height 40H of about 50 nm to about 300 nm and a width 40W of about 50 nm to about 1 μm.Generally, the width 40W of the side boundary features 40 is less than the width 12W of the laser core 12. The separation distance 40S between adjacent side boundary features 40 may be about 50 nm to about 1 μm. The separation distance 12S between the laser core 12 and the adjacent side boundary features 40 may be about 50 nm to 1 μm.As shown in FIG. 2, the side boundary features 40 in the InP p-doped portions 22, 24 may extend parallel to and along a length of the laser core 12 and have a length 40L that is less than or equal to the length 12L of the laser core 12. In this embodiment and all other embodiments with side limiting features 40 described herein, the distal end 12E of the laser core 12 may be aligned with the distal end 40E of each of the side limiting features 40. This alignment ensures that the side boundary features reconfigure the mode of the III-V laser 10 toward the end 12E of the gain layer (laser core 12). However, in practice, minor deviations may be permitted (e.g., ends 40E of side limiting features 40 may be located slightly before or after end 12E of the laser core).According to embodiment, the side boundary features 40 may have a length 40L of about 10 μm to about 10 mm. In general, according to each of the embodiments described herein with side boundary features 40, the number and / or configuration (e.g., height, width, length) of the side boundary features 40 and / or the arrangement of the side boundary features 40 relative to the laser core 12 and relative to each other (e.g., separation distances 40S, 12S) may vary as appropriate and may be modified as needed to account for mode mismatch between the III-V laser 10 and a waveguide or other component of a photonic integrated circuit.Other embodiments of the III-V laser 10 may include a set of one or more asymmetrically arranged side boundary features 40. The number of side limiting features 40 may vary, for example, on each side of the laser core 12, as shown in FIGS. 3 and 4. In this example, three side boundary features 40 may be formed in the p-doped portion 22 of InP, while two side boundary features 40 may be formed in the p-doped portion 24 of InP, where all side boundary features 40 may have the same height 40H, length 40L, width 40W, and pitch 40S.In other embodiments, the number, configuration, and / or arrangement of the side limiting features 40 on each side of the laser core 12 may vary. For example, in FIGS. 5 and 6, two side boundary features 40 may be formed in the p-doped portion 22 from InP, each having a height 40H, a first width 40W 1 and a first separation distance 40S 1 while three side boundary features 40 may be formed in the p-doped portion 24 from InP, each having a height 40H, a second width 40W 2, where 40W 2 > 40W 1, and a second separation distance 40S 2. In this example, the distance 40S 2 between the side boundary features 40 in the p-doped portion 24 of InP may be different (e.g., less) than the distance 40S 1 between the side boundary features 40 in the p-doped portion 22 of InP. As such, the asymmetrically disposed side boundary features 40 may be described as having a different spacing and duty cycle on each side of the laser core 12.Another embodiment of the III-V laser 10 with an asymmetric arrangement of the side limiting features 40 is illustrated in FIGS. 7 and 8. The width and spacings of the side boundary features 40 may vary in one or both of the p-doped portions 22, 24 of InP adjacent the laser core 12, as shown.In the embodiments described above, all side limiting features 40 may have the same height 40H and length 40L. However, in other embodiments, as shown in FIGS. 9 and 10, the side limiting features 40 may have different heights and / or lengths. For example, one or more of the side limiting features 40 in the p-doped portions 22, 24 of InP may have a height 40H 1 and a length 40L 1, while one or more of the other side limiting features 40 in the p-doped portions 22, 24 of InP may have a different height 40H 2 and a different length 40L 2.FIG. 11 illustrates a III-V laser 10 having multi-layered side boundary features 40 according to embodiments. For example, FIG. 11 shows the III-V laser 10 of FIG. 1 with additional side boundary features 40 formed in the n-doped InP portions 28, 30 below and to the side of the laser core 12. As illustrated, the side boundary features 40 formed in the n-doped portions 28, 30 of InP may have the same configuration / arrangement as the side boundary features 40 formed in the p-doped portions 22, 24 of InP. Generally, however, the side boundary features 40 formed in the p-doped portions 22, 24 of InP and / or in the n-doped portions 28, 30 of InP may be formed / arranged in accordance with any of the embodiments described herein.Referring to FIGS. 12 and 13, in accordance with further embodiments, the III-V laser 10 may include a set of one or more vertical confinement features 60 formed adjacent to the laser core 12 (e.g., vertically above and / or below). For example, FIGS. 12 and 13 show an embodiment having a plurality of vertical confinement features 60 formed directly over the laser core 12 in the n-doped portion 20 of InP. Like the side confinement features 40, the vertical confinement features 60 may be formed of the same high refractive index semiconductor material as the laser core 12 (e.g., InGaAsP) or other suitable high refractive index III-V semiconductor materials, e.g., InCaAs, InCaASN, GaAsSb, AlGaAs, or GaAs. In some embodiments, the laser core 12 and the vertical confinement features 60 may be formed from different III-V semiconductor materials. The vertical confinement features 60 may be formed at the same time as the laser core 12 and may have the same height 60H, depending on the embodiment. Moreover, the vertical boundary features 60 may be used in conjunction with any of the embodiments of the side boundary features 40 described herein (e.g., as shown in phantom in FIG. 12 ) or without side boundary features 40.A side view of the vertical confinement features 60 and the laser core 12 of FIG. 12 is illustrated in FIG. 13. According to embodiments, the laser core 12 may have a width 12W of about 1 μm to about 5 μm and a height 12H of about 50 nm to about 300 nm. The vertical confinement features 60 may have a height 60H of from about 5 nm to about 200 nm and a width 60W corresponding to the width 12W of the laser core 12 (e.g., from about 50 nm to about 1 μm). Generally, the height 60H of the vertical confinement features 60 may be less than the height 12H of the laser core 12. the vertical confinement features 60 may be separated as shown by a distance 60S of about 5 nm to about 50 nm, which may be equal to or different from the separation distance 12S between the lowermost vertical confinement feature 60 and the laser core 12. The separation distance 12S between the laser core 12 and the adjacent vertical confinement feature 60 may be about 5 nm to about 50 nm. In some embodiments, the vertical confinement features 60 may have different widths 60W or different widths than the width 12W of the laser core 12.As shown in FIG. 13, the vertical confinement features 60 may extend parallel to and along a length of the laser core 12 and have a length 60L less than or equal to the length 12L of the laser core 12. For example, the vertical delimiting features 60 may have a length 60L of about 10 μm to about 10 mm. In this embodiment and all other embodiments described herein having vertical confinement features 60, the distal end 12E of the laser core 12 may be aligned with the distal end 60E of each of the vertical confinement features 60. In general, according to each of the embodiments described herein having vertical confinement features 60, the number and / or configuration (e.g., height, width, length) of the vertical confinement features 60 and / or the arrangement of the vertical confinement features 60 relative to the laser core 12 and relative to each other (e.g., separation distances 60S, 12S) may vary as appropriate and may be modified as needed to account for mode mismatch between the III-V laser 10 and the waveguide or other component of a photonic integrated circuit.Further embodiments of the III-V laser 10 with vertical confinement features 60 are illustrated in Figures 14-21. For example, in FIGS. 14 and 15, vertical confinement structures 60 having the same height 60H and width 60W may be formed in the p-doped portion 26 of the InP directly below the laser core 12 and not in the n-doped portion 20 directly above the laser core 12 as in FIGS. 12 and 13. As shown in FIGS. 16 and 17, a symmetric array of vertical confinement features 60 having the same height 60H and width 60W may be formed both above and below the laser core 12 in the n-doped portion 20 and the p-doped portion 26, respectively. In this symmetric example, the vertical confinement features 60 formed above and below the laser core 12 may have the same distances 60S and 12S.As shown in FIGS. 18 and 19, vertical confinement features 60 having the same width but different heights 60H 1, 60H 2 may be formed in the n-doped portion 20 above the laser core 12. As shown in FIGS. 20 and 21, the number, spacing, and / or height of the vertical confinement features 60 formed above and below the laser core 12 may vary. Generally, the number, spacing, placement, and / or configuration of the vertical confinement features 60 with respect to the laser core 12 may vary depending on the application and may be modified as necessary to avoid mis-matching of the laser modes.An illustrative method of fabricating a III-V laser 10 having side boundary features 40 is illustrated in FIGS. 22-28.FIG. 22 shows a semiconductor substrate 100 comprising an undoped indium phosphide (InP) layer 102 overlying a p-doped InP layer 104. As shown in FIG. 23, one or more doping processes 106 (e.g., ion implantation) may be performed to form an n-doped portion 108 of InP, an n-doped portion 110 of InP, and a p-doped portion 112 of InP between the n-doped portions 108, 110 of InP. After doping, as shown in FIG. 24, a layer 114 of InGaAsP may be formed (e.g., by epitaxy) on the doped portions 108, 110, 112 of InP.FIG. 25 shows the structure of FIG. 24 after one or more masking and etching steps have been performed to selectively remove portions of the layer 114 of InGaAsP. Comparing FIG. 25 with FIG. 1, it can be seen that the remaining portion 116 of the layer 114 of InGaAsP corresponds to the laser core 12 and the remaining portions 118 of the layer 114 of InGaAsP correspond to the side boundary features 40 of the III-V laser 10 shown in FIG. 1.FIG. 26 shows the structure of FIG. 25 after an undoped indium phosphide (InP) layer 120 is formed (e.g., by epitaxy) over the remaining portions 116, 118 of the InGaAsP layer 114 and over the doped InP portions 108, 110, 112. As shown in FIG. 27, one or more doping processes 122 (e.g., ion implantation) may be performed to form a p-doped portion 124 of InP, a p-doped portion 126 of InP, and an n-doped portion 128 of InP between the p-doped portions 124, 126 of InP. FIG. 28 shows the structure of FIG. 27 after an n-doped layer 130 of InP is formed over the doped portions 124, 126, 128 of InP.An illustrative method of fabricating a III-V laser 10 having vertical confinement structures 60 is illustrated in Figures 29-33.FIG. 29 shows the structure of FIG. 24 after one or more masking steps have been performed to selectively remove portions of the layer 114 of InGaAsP. Comparing FIG. 29 with FIG. 1, it can be seen that the remaining portion 116 of the layer 114 of InGaAsP corresponds to the laser core 12 of the III-V laser 10.FIG. 30 shows the structure of FIG. 29 after an undoped layer (not shown) of InP is formed (e.g., by epitaxy) over the remaining portion 116 of the layer 114 of InGaAsP and over the doped portions 108, 110, 112 of InP and subsequently doped by one or more doping processes 132 (e.g., ion implantation). This step forms a p-doped portion 134 of InP, a p-doped portion 136 of InP, and an n-doped portion 138 of InP between the p-doped portions 134, 136 of InP.FIG. 31 shows the structure of FIG. 30 after multiple additional processes have been performed. One or more masking / etching steps were performed to selectively remove a portion of the n-doped portion 138 of InP. Subsequently, a layer 140 of InGaAsP was formed (e.g., by epitaxy) over the remaining n-doped portion 138 of InP.FIG. 32 illustrates the structure of FIG. 31 after multiple additional processes have been performed. After forming a layer 142 of n-doped InP over the layer 140 of InGaAsP, another layer 144 of InGaAsP was formed over the layer 142 of n-doped InP.FIG. 33 shows the structure of FIG. 32 after multiple additional processes have been performed. After forming a layer 146 of n-doped InP over the layer 144 of InGaAsP, a layer 148 of n-doped InP was formed over the doped portions 134, 136, 146. Comparing FIG. 33 with FIG. 12, it can be seen that the remaining portion 116 of the layer 114 of InGaAsP corresponds to the laser core 12 and the layers 142, 144 of InGaAsP correspond to the vertical delimiting features 60 of the III-V laser 10 illustrated in FIG. 12.The use of side confinement features and / or vertical confinement features in a III-V laser increases the coupling efficiency between the III-V laser and a photonic integrated circuit waveguide (e.g., an inversely tapered Si waveguide of a Si-based photonic integrated circuit). The side confinement features and / or the vertical confinement features may be selectively configured to adjust the mode size of the III-V laser (e.g., along a lateral direction) to better match the mode size of the waveguide, resulting in improved coupling efficiency.The above-described method is used in the production of PIC (Photonic Integrated Circuit) chips. The resulting PIC chips may be sold by the manufacturer as a green wafer (i.e., as a single wafer with multiple unpackaged chips), as a bare chip, or in packaged form. In the latter case, the chip is incorporated into a single chip package (e.g., a plastic carrier having terminals attached to a motherboard or other parent carrier) or into a multichip package (e.g., a ceramic carrier having either surface interconnections or buried interconnections). In either case, the chip is then integrated with other chips, discrete circuit elements, and / or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The final product can be any product that includes integrated circuit chips, ranging from toys and other simple applications to advanced computer products having a display, keyboard, or other input device, and a central processor.The particular embodiments set forth above are illustrative only, as the invention may be modified and practiced in various but equivalent ways. For example, the method steps described above can be carried out in a different order. It should be noted that the use of terms such as "first," "second," "third," or "fourth" to describe various processes or structures in this specification and the appended claims is only for brief reference to such steps / structures and does not necessarily mean that these steps / structures are performed / formed in this ordered order. Depending on the exact wording of the claim, an ordered sequence of such methods may or may not be required, of course.

Claims

A semiconductor laser structure of a III-V semiconductor material, comprising: a laser core (12) formed of a III-V semiconductor material having a high refractive index and embedded in a dielectric matrix (14); wherein the dielectric matrix (14) is formed of a first III-V semiconductor material formed of a material having a lower refractive index than the laser core (12); wherein the dielectric matrix (14) is arranged in a vertical direction between a p-doped layer (18) and an n-doped layer (16), wherein the part of the dielectric matrix (14) arranged adjacent to the n-doped layer (16) has an n-doped section (20) arranged laterally between p-doped sections (22, 24), and wherein the part of the dielectric matrix (14) arranged adjacent to the p-doped layer (18) has a p-doped section (26) arranged laterally between n-doped sections (28, 30); and a plurality of side boundary features (40) formed in the dielectric matrix (14) and extending parallel to and along a length of the laser core (12), the side boundary features (40) being formed laterally adjacent to the laser core (12), the plurality of side boundary features (40) comprising the high refractive index III-V semiconductor material.The laser structure of claim 1, wherein the high refractive index III-V semiconductor material comprises indium gallium arsenide phosphide (InGaAsP).The laser structure of claim 1, wherein the first III-V semiconductor material comprises indium phosphide (InP).The laser structure of claim 1, wherein the plurality of side boundary features (40) comprises: a first set of side boundary features (40) formed within the dielectric matrix (14) and extending parallel to and along a length of a first side of the laser core (12); and a second set of side boundary features (40) formed within the dielectric matrix (14) and extending parallel to and along a length of a second, opposite side of the laser core (12).The laser structure of claim 4, wherein the first set of side boundary features (40) and the second set of side boundary features (40) are symmetrically disposed with respect to the laser core (12).The laser structure of claim 4, wherein the first set of side boundary features (40) and the second set of side boundary features (40) are asymmetrically arranged with respect to the laser core (12).The laser structure of claim 1, wherein the laser core (12) is formed in a region of the dielectric matrix (14) of a first doping type and wherein the plurality of side boundary features (40) are formed in regions of the dielectric matrix (14) of a second doping type.A semiconductor laser structure of a III-V semiconductor material, comprising: a laser core (12) formed of a III-V semiconductor material having a high refractive index and embedded in a dielectric matrix (14); wherein the dielectric matrix (14) is formed of a first III-V semiconductor material formed of a material having a lower refractive index than the laser core (12); wherein the dielectric matrix (14) is arranged in a vertical direction between a p-doped layer (18) and an n-doped layer (16), wherein the part of the dielectric matrix (14) arranged adjacent to the n-doped layer (16) has an n-doped section (20) arranged laterally between p-doped sections (22, 24), and wherein the part of the dielectric matrix (14) arranged adjacent to the p-doped layer (18) has a p-doped section (26) arranged laterally between n-doped sections (28, 30); and a plurality of vertical confinement features (60) formed in the dielectric matrix (14) and extending parallel to and along a length of the laser core (12), the vertical confinement features (60) being formed vertically adjacent to the laser core (12), the plurality of vertical confinement features (60) comprising the high refractive index III-V semiconductor material.The laser structure of claim 8, wherein the high refractive index III-V semiconductor material comprises indium gallium arsenide phosphide (InGaAsP).The laser structure of claim 8, wherein the first III-V semiconductor material comprises indium phosphide (InP).The laser structure of claim 8, wherein the plurality of vertical confinement features (60) are formed in the dielectric matrix (14) vertically above the laser core (12), or vertically below the laser core (12), or vertically above and below the laser core (12).The laser structure of claim 11, wherein the plurality of vertical confinement features (60) are arranged symmetrically to the laser core (12).The laser structure of claim 11, wherein the plurality of vertical confinement features (60) are arranged asymmetrically to the laser core (12).The laser structure of claim 8, wherein the laser core (12) is formed in a region of the dielectric matrix (14) of a first doping type and wherein at least a portion of the plurality of vertical confinement features (60) is formed in one or more regions of the dielectric matrix (14) of a second doping type.A laser system comprising a laser structure according to claim 1 or claim 8 and a waveguide (52) optically coupled to the laser structure, wherein the plurality of confinement features (40, 60) are configured such that a size and a mode profile of the laser structure is matched to a mode of the waveguide.The laser system of claim 15, wherein the plurality of confinement features (40, 60) are arranged symmetrically to the laser core (12).

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