Vertical-cavity surface-emitting laser (VCSEL) emitter with guided-unguided waveguides

Abstract

To provide a vertical cavity surface emitting laser (VCSEL) device that includes a VCSEL emitter having a waveguide having a guided portion and an antiguided portion.SOLUTION: Guided and antiguided portions can select and constrain the mode of VCSEL emitters, and the antiguided portion can be used to coherently couple adjacent VCSEL emitters.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Lasers are commonly used in a variety of applications, such as data communications, 3D sensing, and LIDAR, and are a component of many modern devices. [Background technology]

[0002] One application that is becoming more common is the use of lasers in data networks. Lasers are used in many fiber optic communication systems to transmit digital data over the network. In one exemplary configuration, a laser can be modulated with digital data to produce an optical signal that includes periods of bright and dark outputs that represent a binary data stream. In actual operation, the laser outputs a high optical output that represents a binary high and a lower power optical output that represents a binary low. To obtain a fast response time, the laser is always on but fluctuates from high to lower optical outputs.

[0003]

[0002] Optical networks offer various advantages over other types of networks, such as copper-wire-based networks. For example, many existing copper-wire networks operate at nearly the maximum data transmission speeds and distances possible for copper-wire technology. On the other hand, many existing optical networks exceed the maximum possible for copper-wire networks in terms of both data transmission speed and distance. That is, optical networks can reliably transmit data at faster speeds and over greater distances than is possible with copper-wire networks.

[0004] One type of laser used in optical data transmission is the Vertical Cavity Surface Emitting Laser (VCSEL) device. As the name suggests, a VCSEL device has a laser cavity sandwiched between and defined by two mirror stacks. VCSEL devices are typically constructed on a semiconductor wafer, such as gallium arsenide (GaAs). VCSEL devices include a bottom mirror constructed on the semiconductor wafer. The bottom mirror typically includes several alternating high- and low-index layers. When light travels from one index-of-refraction layer to another, a portion of the light is reflected in phase. Such mirrors are commonly called distributed Bragg reflectors (DBRs). By using a sufficient number of alternating layers, as much as approximately 99.9% of the light can be reflected by the mirror. The top mirror can also be implemented as a DBR, but with a lower reflectivity (e.g., about 98%) than the upper mirror, and light between the top and bottom mirrors can escape orthogonally from the top mirror. An electrically pumped active region containing quantum wells (QWs) with population inversion can amplify the light reflected between the top and bottom mirrors, thus producing coherent laser emission. Summary of the Invention

[0005] A VCSEL device and a method for forming such a VCSEL device are shown and / or described in connection with at least one of the figures and more fully set forth in the claims.

[0006]

[0005] These and other advantages, aspects, and novel features of the present disclosure, as well as details of exemplary embodiments thereof, will be more thoroughly understood from the following description and drawings.

[0006] Various features and advantages of the present disclosure can be seen in the following detailed description taken in conjunction with the accompanying drawings. It will then be easier to understand.In the accompanying drawings, the same reference numbers refer to similar structural elements. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view of a semiconductor device that constitutes a vertical cavity surface emitting laser (VCSEL) device including a waveguide having a guided portion and a non-guided portion. [Figure 2]

[0008] 2 is a flow chart of an exemplary method for manufacturing the semiconductor device of FIG. 1. [Figure 3A]

[0009] 3A-3D show the semiconductor device of FIG. 1 at various stages of the manufacturing method of FIG. 2; [Figure 3B] 3A-3D show the semiconductor device of FIG. 1 at various stages of the manufacturing method of FIG. 2; [Figure 3C] 3A-3D show the semiconductor device of FIG. 1 at various stages of the manufacturing method of FIG. 2; [Figure 3D] 3A-3D show the semiconductor device of FIG. 1 at various stages of the manufacturing method of FIG. 2; [Figure 3E] 3A-3D show the semiconductor device of FIG. 1 at various stages of the manufacturing method of FIG. 2; [Figure 3F] 3A-3D show the semiconductor device of FIG. 1 at various stages of the manufacturing method of FIG. 2; [Figure 4A]

[0010] FIG. 4A is a diagram illustrating the effective refractive index of various waveguides having guided and / or non-guided portions. [Figure 4B] FIG. 4B shows the effective refractive index of various waveguides having guided and / or non-guided portions. [Figure 4C] FIG. 4C shows the effective refractive index of various waveguides having guided and / or non-guided portions. [Figure 4D] FIG. 4D shows the effective refractive index of various waveguides having guided and / or non-guided portions. [Figure 5]

[0011] FIG. 1 illustrates the mode filtering aspects of an embodiment of a waveguide having guided and non-guided portions. [Figure 6]

[0012] FIG. 1 illustrates the effective refractive index of a waveguide for a VCSEL device having two coherently coupled VCSEL emitters. [Figure 7]

[0013] FIG. 7 illustrates optical mode intensity profiles corresponding to the coherently coupled VCSEL emitters of FIG. 6. [Figure 8]

[0014] FIG. 1 illustrates an embodiment of a VCSEL device having two coherently coupled VCSEL emitters, with respective effective refractive indices Δn eff provided by guided and unguided portions of such VCSEL emitters. [Figure 9] FIG. 1 illustrates an embodiment of a VCSEL device having two coherently coupled VCSEL emitters, with respective effective refractive indices Δn eff provided by guided and unguided portions of such VCSEL emitters. DETAILED DESCRIPTION OF THE INVENTION

[0008]

[0015] The following discussion provides various examples of VCSEL devices and methods of fabricating VCSEL devices. Such examples are non-limiting, and the scope of the appended claims should not be limited to the particular examples disclosed. In the following discussion, the terms "example" and "for example" are non-limiting.

[0009]

[0016] These figures show general structural patterns, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the present disclosure. Additionally, elements in the figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in these figures may be changed to help improve understanding of the examples discussed in this disclosure. The same reference numbers in different figures refer to the same elements.

[0010]

[0017] The term "or" means any one or more of the items in the list connected by "or." As an example, "x or y" means any element of the three-element set {(x),(y),(x,y)}. As another example, "x, y, or z" means any element of the seven-element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}.

[0011]

[0018] The terms "comprises," "comprising," "includes," and / or "including" are "open-ended" terms that specify the presence of stated features but do not exclude the presence or addition of one or more other features.

[0012]

[0019] Terms such as "first," "second," and the like may be used herein to describe various elements, and these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Thus, for example, a first element discussed in this disclosure could also be referred to as a second element without departing from the teachings of the disclosure.

[0013]

[0020] Unless otherwise specified, the term "coupled" can be used to describe two elements in direct contact with each other, or two elements that are indirectly connected by one or more other elements. For example, if element A is said to be coupled to element B, element A can be in direct contact with element B, or it can be indirectly connected to element B by an intervening element C. Similarly, the terms "over" or "on" can be used to describe two elements in direct contact with each other, or two elements that are indirectly connected by one or more other elements.

[0014]

[0021] Generally, aspects of the present disclosure are directed to a vertical cavity surface emitting layer (VCSEL) device comprising one or more VCSEL emitters having a vertical cavity defining a waveguide having both guided and non-guided portions. In some embodiments, the VCSEL device can include a VCSEL emitter having a guided and / or non-guided portion positioned between a top mirror and an active region of the VCSEL emitter. Additionally, the VCSEL device can include a VCSEL emitter having a guided and / or non-guided portion positioned between a bottom mirror and an active region of the VCSEL emitter.

[0015]

[0022] 1, an exemplary embodiment of a semiconductor device, a vertical cavity surface emitting laser (VCSEL) device 100, is shown. As shown, the VCSEL device 100 comprises a semiconductor substrate 110, a bottom contact layer 120, a VCSEL emitter 125 on the semiconductor substrate 110, a passivation layer 180, and a top contact layer 190. The substrate 110 may be doped with a first type of impurity (e.g., a p-type or n-type dopant). The bottom contact layer 120 may contact a bottom surface of the substrate 110.

[0016]

[0023] The VCSEL emitter 125 can include a bottom mirror 130, a non-guiding portion 140, an active region 150, a guiding portion 160, and a top mirror 170. The bottom mirror 130 can be located on a substrate 110, and the non-guiding portion 140 can be located on the bottom mirror 130. In various embodiments, the bottom surface of the bottom mirror 130 can contact the top surface of the substrate 110, and the bottom surface of the non-guiding portion 140 can contact the top surface of the bottom mirror 130.

[0017]

[0024] As further shown, active region 150 can be located above non-inductive portion 140. As shown, active region 150 can include a lower active layer 152, a tunnel junction layer 154, and an upper active layer 156. In various embodiments, a bottom surface of lower active layer 152 can contact a top surface of non-inductive portion 140, a bottom surface of tunnel junction layer 154 can contact a top surface of lower active layer 152, and a bottom surface of upper active layer 156 can contact a top surface of tunnel junction layer 154. Inductive portion 160 can be located above active region 150. In various embodiments, a bottom surface of inductive portion 160 can contact a top surface of upper active layer 156 of active region 150.

[0018]

[0025] As further shown, the top mirror 170 can be located above the inductive portion 160, the passivation layer 180 can be located above the top mirror 170, and the top contact layer 190 can be located above the passivation layer 180. In various embodiments, the bottom surface of the top mirror 170 can contact the top surface of the inductive portion 160, the bottom surface of the passivation layer 180 can contact the top surface of the top mirror 170, and the bottom surface of the top contact layer 190 can contact the top surface of the passivation layer 180. Furthermore, the bottom surface of the top contact layer 190 can pass through an opening in the passivation layer 180 and contact the top surface of the top mirror 170. Furthermore, the top contact layer 190 can include an aperture 194 above a vertical cavity 196 of the VCSEL emitter 125, which allows light from the vertical cavity 196 to pass through the top surface of the top mirror 170.

[0019]

[0026] The bottom mirror 130 can comprise a distributed Bragg reflector (DBR) stack of alternating layers 132, 134. In various embodiments, the alternating layers 132, 134 can include alternating high and low refractive index layers (e.g., alternating AlGaAs and AlAs layers). However, in other embodiments, the alternating layers 132, 134 of the bottom mirror 130 can include other III-V semiconductor materials. The layers 132, 134 of the bottom mirror 130 can be doped or undoped. Furthermore, the doping can be n-type or p-type, depending on the particular VCSEL design and the doping type of the substrate 110. However, other types of VCSEL mirrors can also be used.

[0020]

[0027] Similarly, the top mirror 170 can also comprise a distributed Bragg reflector (DBR) stack of alternating layers 172, 174. In various embodiments, the alternating layers 172, 174 can include alternating high and low refractive index layers (e.g., alternating AlGaAs and AlAs layers). However, in other embodiments, the alternating layers 172, 174 of the top mirror 170 can also include other III-V semiconductor materials. The layers 172, 174 of the top mirror 170 can be doped or undoped. Furthermore, the doping can be n-type or p-type, depending on the particular VCSEL design. However, other types of VCSEL mirrors can also be used.

[0021]

[0028] The bottom contact layer 120 and the top contact layer 190 may form an ohmic contact that electrically biases the VCSEL emitter 125. When the VCSEL emitter 125 is forward biased, with a voltage across the top contact layer 190 different from the voltage across the bottom contact layer 120, the active region 150 may emit light that reflects between the top mirror 170 and the bottom mirror 130 and ultimately passes through an aperture 194 in the top mirror 170 and the top contact layer 190. Those skilled in the art will appreciate that other configurations of the contact layers 120, 190 may be used to generate a voltage across the active region 150 and generate light.

[0022]

[0029] Referring now to FIG. 2, an exemplary method for fabricating the VCSEL device 100 of FIG. A flow diagram is presented for the method 200. As described in more detail below, the method 200 of Figure 2, in some embodiments, utilizes three or more epitaxial growth processes to form the various structures of the VCSEL device 100.

[0023]

[0030] At 210, a first epitaxial growth process is performed. As shown in FIG. 3A , the first epitaxial growth process can grow alternating layers 132, 134 of the bottom mirror 130 on the top surface of the substrate 110. In various embodiments, the layers 132, 134 can define the n-DBR mirror 130 on the substrate 110. After forming the bottom mirror 130, the first epitaxial growth process can further grow a waveguide underlayer 141 on the top surface of the bottom mirror 130. For example, a pn layer can be grown on the top surface of the bottom mirror 130.

[0024]

[0031] After the first epitaxial growth process, a first lithography process at 220 can pattern the waveguide underlayer 141 and remove a portion of the waveguide underlayer 141 to form the non-guiding portion 140. As shown in Figure 3B, the lithography process can form an aperture 142 through the waveguide underlayer 141 to obtain the non-guiding portion 140. In particular, the aperture 142 can be lithographically defined, and the p-layer can be etched away to define a partial n-cavity for current flow.

[0025]

[0032] After forming the non-inductive portion 140 via the first lithography process, a second epitaxial process 230 can grow the active region 150 and the waveguide overlayer 161, as shown in FIG. 3C . In particular, the second epitaxial process can grow a lower active layer 152 on the top surface of the non-inductive portion 140, the lower active layer 152 including quantum wells, quantum dots, and / or quantum dashes. The second epitaxial growth process can further grow a tunnel junction layer 154 on the top surface of the lower active layer 152, and an upper active layer 156 on the top surface of the tunnel junction layer 154, the upper active layer 156 including quantum wells, quantum dots, and / or quantum dashes. In embodiments having multiple active layers, such as layers 152, 156, the second epitaxial process can include several cycles of growing the active layers and tunnel junction layers, such that the VCSEL emitter 125 optionally comprises three or more active layers 152, 156. The second epitaxial process may also grow a waveguide superposition layer 161 on top of the upper active layer 156. In some embodiments, the waveguide superposition layer 161 may simply comprise the last tunnel junction layer grown in a cycle of growing an active layer and a tunnel junction layer.

[0026]

[0033] After the second epitaxial growth process, a second lithography process at 240 can pattern the waveguide overlayer 161 and remove a portion of the waveguide overlayer 161 to form the non-guiding portion 140. As shown in FIG. 3D , the lithography process can define an inner area or aperture 162 and remove an area or portion outside the defined aperture 162. In this manner, the lithography process can define the inner area or aperture 162 for current flow and complete the n-cavity 196 of the VCSEL emitter 125. In various embodiments, a highly doped (10 19 cm -3A reverse-biased pn junction may provide the tunnel junction aperture 162. Current flows through the tunnel junction aperture. Outside the tunnel junction, the current is blocked by a reverse-biased pn junction. In such an embodiment, a pn junction with a breakdown voltage greater than 5 volts may be implemented.

[0027]

[0034] After forming the inductive portion 160 through the second lithography process, the top mirror 170 can be grown by a third epitaxial process at 250. In particular, the third epitaxial process grows a top mirror 170 on the top surface of the inductive portion 160, as shown in FIG. Alternating layers 172, 174 of the top mirror 170 may be grown.

[0028]

[0035] After forming the top mirror 170, various processing steps at 260 can complete the formation of the VCSEL device 100, as shown in FIG. 3F. In particular, a bottom contact layer 120 can be formed on the bottom surface of the substrate 110, and a passivation layer 180 can be formed on the top surface of the top mirror 170. An opening 182 can be etched through the passivation layer 180, and a top contact layer 190 can be formed on the top surface of the passivation layer 180, with the top contact layer 190 extending through the opening 182 and contacting the top surface of the top mirror 170. Additionally, as shown, the top contact layer 190 can be formed such that an aperture 194 through the top contact layer 190 is positioned over the vertical cavity 196 of the VCSEL emitter 125.

[0029]

[0036] In various embodiments, the non-guided portion 140 and the guided portion 160 define a waveguide, providing both guided and non-guided elements within the same VCSEL emitter 125. The effective refractive index of the inner portion of the guided portion 160 is higher than the effective refractive index of the outer portion. Therefore, light traveling through the guided portion 160 is confined to the guided portion. Conversely, the effective refractive index of the inner portion of the non-guided portion 140 is lower than the effective refractive index of the outer portion. Therefore, light traveling through the non-guided portion 140 leaks out of the non-guided portion 140. For example, the guided portion 160 can include a tunnel junction aperture, providing a waveguide with the guided portion 160 that restricts current flow through the tunnel junction aperture. Additionally, the non-guided portion 140 can include a blocking pn layer with an aperture 142, which further restricts current flow through the aperture 142. In this manner, the VCSEL emitter 125 can confine current from above and below the active region 150 to improve efficiency. In addition to confining the current, the waveguide of the VCSEL emitter 125 includes both inductive and non-inductive sections that aid in the generation of light between the mirrors 130 , 170 and / or the optical coupling between adjacent VCSEL emitters 125 .

[0030]

[0037] In particular, the lateral waveguides within the VCSEL emitter 125 can be defined by an effective refractive index step, where the effective refractive index step (Δn) is related to the wavelength difference (Δλ) inside and outside the waveguide.

[0031]

number

[0032] where λ is the wavelength within the vertical cavity 196 and n is the effective refractive index within the cavity. The emission wavelength of the VCSEL emitter 125 is defined by the thickness of the optical cavity, n × d, where d is the thickness or height of the vertical cavity 196. Thus, the thicknesses of the non-guiding portion 140 and the guiding portion 160 define the corresponding etch depth of the vertical cavity 196. Thus, by controlling the thickness of such overgrown material used to form the non-guiding portion 140 and the guiding portion 160, the VCSEL emitter 125 can achieve the desired It can be designed to have waveguides with inductive and non-inductive properties.

[0033]

[0038] Examples of such waveguides are shown in Figures 4A-4D. In particular, Figure 4A shows the effective lateral refractive index step Δn of a waveguide (e.g., the tunnel junction aperture described above) that includes only a guided portion 160 that provides the guided characteristics. Conversely, Figure 4B shows the effective lateral refractive index step Δn of a waveguide (e.g., the pn active region described above) that includes only a non-guided portion 140 that provides the non-guided characteristics. Figures 4C and 4D show the effective lateral refractive index step Δn of a more complex waveguide that includes a guided portion 160 that provides the guided characteristics and a non-guided portion 140 that provides the non-guided characteristics. In particular, the waveguides of Figures 4C and 4D include tunnel junction apertures 162 and / or pn blocking layer apertures 142 that differ in thickness and / or lateral dimensions (e.g., diameter, width, etc.). More specifically, Figure 4C shows a waveguide in which aperture 162 of guiding portion 160 is aligned (e.g., coaxially aligned) with aperture 142 of non-guiding portion 140, with aperture 162 having a smaller diameter than small aperture 142. Conversely, Figure 4D shows a waveguide in which aperture 162 of guiding portion 160 is aligned (e.g., coaxially aligned) with aperture 142 of non-guiding portion 140, with aperture 162 having a larger diameter than aperture 142.

[0034]

[0039] The use of a waveguide having both a guided portion 160 with guided properties and a non-guide portion 140 with non-guide properties provides the VCSEL emitter 125 with additional flexibility in terms of mode selection. Both the guided portion 160 and the non-guide portion 140 described above restrict current flow to their respective apertures 142, 162. However, various embodiments of the VCSEL emitter 125 may not require current restriction from both sides of the active region 150. In such embodiments, restricting current through either the guided portion 160 or the non-guide portion 140 may be sufficient. Thus, other layers can simply vary the thickness of the vertical cavity 196 to guide or non-guide light without further restricting current flow.

[0035]

[0040] 5, the guiding properties of the guiding portion 160 and the non-guiding properties of the non-guiding portion 140 can be combined to provide a mode filter element. For example, the guiding portion 160 can comprise a tunnel junction aperture 162, whose effective transverse refractive index Δn eff is the effective lateral refractive index Δn provided by the pn blocking layer of the non-guiding portion 140 and its aperture 142. eff In particular, the guided section 160 can be designed to guide and confine the fundamental mode of light emitted by the active region 150. At the same time, the non-guided section 140 can be designed so that the second-mode light emitted by the active region 150 extends outside the optical waveguide provided by the guided section 160 and overlaps with the non-guided section of the non-guided section 140. Such non-guided sections allow the second-mode light to leak, resulting in greater optical loss. Without such non-guided sections, the second-mode light would also be confined, but with greater optical loss. However, at a certain current value, this mode overcomes the loss and begins lasing, producing a kink in the LI curve. Therefore, the combination of the non-guided section 140 and the guided section 160 can improve the optical power in a single-mode VCSEL emitter.

[0036]

[0041] In addition to and / or as an alternative to mode selection, waveguides with both guiding and anti-guiding properties can be used to promote phase coupling between adjacent VCSEL emitters 125 of a VCSEL device. In particular, waveguides with anti-guiding properties between adjacent VCSEL emitters 125 can promote coherent coupling. Thus, the use of anti-guiding properties can provide another degree of freedom in designing a coherent VCSEL array, which can help to produce a desired / unique far-field pattern.

[0037]

[0042] In this regard, FIG. 6 illustrates the effective refractive index profile Δn of a suitable waveguide for coherently coupling adjacent VCSEL emitters 125 of a VCSEL device. eff 7 shows the optical mode intensity profile corresponding to coherently coupled VCSEL emitters 125 with circular apertures. Thus, adjacent VCSEL emitters 125 can be constructed with waveguides comprising a guided portion 160 with a tunnel junction aperture 162 and a non-guided portion 140 with a pn blocking layer aperture 142, which can be combined to produce a desired effective refractive index profile Δn eff In particular, the tunnel junction aperture 162 can be configured to provide an effective refractive index step that is greater than the effective refractive index step provided by the pn blocking layer aperture 142. In this manner, the guided portion 160 can guide and provide overall confinement of the optical mode in the two VCSEL emitters 125. Additionally, the non-guided portion 140 can non-guide the optical mode and control the coupling coefficient between adjacent VCSEL emitters 125. In such embodiments, the non-guided portion 140 can be used to design either an in-phase or out-of-phase array of coupled VCSEL emitters 125.

[0038]

[0043] 6 and 7 show two coupled VCSEL emitters 125 of the VCSEL device 100, the number of coupled VCSEL emitters 125 is not limited to two. For example, a coupled array of VCSEL emitters 125 can include a one-dimensional array with various quantities of VCSEL emitters 125 (e.g., 1×2, 1×3, 1×4, etc.). Furthermore, a coupled array of VCSEL emitters 125 can include a two-dimensional array with various quantities of VCSEL emitters 125 (e.g., 2×2, 2×4, 4×4, etc.). Furthermore, the waveguide characteristics can vary the phase and coupling strength between adjacent VCSEL emitters 125 of the array, thereby providing additional degrees of freedom for designing the far-field pattern. In addition to or as an alternative to the regular 1D or 2D arrays described above, the VCSEL device 100 may include a coupled array of VCSEL emitters 125 arranged in an irregular 1D or 2D array in which the distance, phase coupling conditions, and / or coupling strength between the VCSEL emitters 125 vary.

[0039]

[0044] In addition to and / or as an alternative to the coupling discussed above, the non-guided properties of the non-guided portion 140 can be used as a VCSEL array mode filter. To this end, Figures 8 and 9 show embodiments of two coherently coupled VCSEL emitters 125. As shown in Figure 8, the effective refractive index Δn provided by the tunnel junction aperture 162 in the guided portion 160 eff is the effective refractive index Δn of the pn blocking layer aperture 142 in the non-guiding portion 140 eff8 can be larger compared to the mode selection described above in connection with FIG. 5. The mode selection provided by the waveguide sections 140, 160 of FIG. 8 functions similarly to the mode selection described above in connection with FIG. 5. That is, the waveguide sections 140, 160 associated with FIG. 8 cooperate to provide high loss for higher order modes. Such a configuration of waveguide sections 140, 160 can be used to design a high single-mode power coherently coupled array of VCSEL emitters 125. In particular, the left side of FIG. 9 shows the effective refractive index profile of the waveguide sections 140, 160 for two coherently coupled VCSEL emitters 125. The right side of FIG. 9 shows the resulting mode intensity of the coupled VCSEL emitters 125 due to the guided and non-guided characteristics provided by the guided and non-guided sections 160, 140. Only the zeroth order mode is confined.

[0040]

[0045] The above embodiments generally involve a positive effective refractive index step Δn eff A tunnel junction aperture 162 is utilized for the inductive portion 160 that provides the tunnel junction. However, it is possible to use a pn blocking layer with an aperture similar to aperture 142. In such an embodiment, the VCSEL emitter 125 may include two pn blocking layer apertures, one above and one below the active region 150.

[0041]

[0046] Additionally, in the above-described embodiments, any retained or removed material of the apertures 142, 162 may be generally circular. However, in other embodiments, the waveguide portions 140, 160 may include different numbers of apertures (e.g., 0, 1, 2, 3, etc.) and / or different shapes (e.g., oval, square, rectangular, annular, etc.) to define appropriate waveguide and / or current-confining structures. Furthermore, while the above-described embodiments of the VCSEL device 100 include a VCSEL emitter 125 having a single inductive portion 160 above the active region 150, other embodiments may include one or more non-inductive portions and / or one or more inductive portions above the active region 150. Similarly, while the above-described embodiments of the VCSEL device 100 include a VCSEL emitter 125 having a single non-inductive portion 140 below the active region 150, other embodiments may include one or more non-inductive portions and / or one or more inductive portions below the active region 150.

[0042]

[0047] While the present disclosure includes reference to particular examples, those skilled in the art will recognize that various changes can be made and equivalents can be substituted without departing from the scope of the present disclosure. Additionally, modifications can be made to the disclosed examples without departing from the scope of the present disclosure. Accordingly, the present disclosure is not limited to the disclosed examples, but rather is intended to include all examples that fall within the scope of the appended claims. [Explanation of symbols]

[0043] 100 Vertical Cavity Surface Emitting Laser (VCSEL) Devices 110 Semiconductor substrate 120 Lower contact layer 125 VCSEL emitter 130 Lower mirror 132 Alternating layers 134 Alternating layers 140 Non-inductive part 141 Waveguide lower layer 142 aperture 150 active area 152 Lower active layer 154 Tunnel Junction Layer 156 Upper active layer 160 Induction part 161 Waveguide upper layer 162 aperture 170 Upper mirror 172 Alternating layers 174 Alternating layers 180 Passivation Layer 182 Aperture 190 Upper contact layer 194 aperture 196 Vertical resonator

Claims

1. An upper mirror; A lower mirror; an active region between the top mirror and the bottom mirror; an upper waveguide between the upper mirror and the active region, an inner portion of the upper waveguide having a higher effective refractive index than an outer portion of the upper waveguide; a lower waveguide between the active region and the lower mirror, an inner portion of the lower waveguide having a lower effective refractive index than an outer portion of the lower waveguide; wherein the inner portion of the upper waveguide has a larger lateral dimension than the inner portion of the lower waveguide.

2. 10. The semiconductor device of claim 1, a semiconductor substrate including a top substrate surface and a bottom substrate surface; Including, the bottom surface of the bottom mirror is on the top surface of the substrate; Semiconductor substrate.

3. 3. The semiconductor device of claim 2, a bottom contact layer on the bottom surface of the substrate; a top contact layer on the top mirror; Including, the active region emits light in response to an electrical bias applied between the bottom contact layer and the top contact layer; Semiconductor devices.

4. 10. The semiconductor device of claim 1, the top mirror includes alternating layers of a first material and a second material; the first material has a higher effective refractive index than the second material; Semiconductor devices.

5. 5. The semiconductor device of claim 4, wherein the bottom mirror comprises alternating layers of the first material and the second material.

6. 10. The semiconductor device of claim 1, wherein the active region comprises at least one of a quantum well, a quantum dot, and a quantum dash.

7. 10. The semiconductor device of claim 1, wherein the inner portion of the upper waveguide comprises a pn junction.

8. 1. A semiconductor device including an array of VCSEL emitters, Each VCSEL emitter of the array of VCSEL emitters comprises: An upper mirror; A lower mirror; an active region between the top mirror and the bottom mirror; an upper waveguide between the upper mirror and the active region, an inner portion of the upper waveguide having a higher effective refractive index than an outer portion of the upper waveguide; a lower waveguide between the active region and the lower mirror, an inner portion of the lower waveguide having a lower effective refractive index than an outer portion of the lower waveguide; wherein the inner portion of each upper waveguide has a larger lateral dimension than the inner portion of its respective lower waveguide.

9. 9. The semiconductor device of claim 8, each VCSEL emitter includes a bottom contact layer below the bottom mirror and a top contact layer above the top mirror; the active region of each VCSEL emitter emitting light in response to an electrical bias applied between its respective bottom contact layer and its respective top contact layer; Semiconductor devices.

10. 9. The semiconductor device of claim 8, Each bottom mirror includes alternating layers of a first semiconductor and a second semiconductor; the first semiconductor has a higher effective refractive index than the second semiconductor; Semiconductor devices.

11. 11. The semiconductor device of claim 10, wherein each top mirror comprises alternating layers of the first semiconductor and the second semiconductor.

12. 10. The semiconductor device of claim 8, wherein each active region includes at least one of a quantum well, a quantum dot, and a quantum dash.

13. 9. The semiconductor device of claim 8, wherein the inner portion of each upper waveguide comprises a pn junction.

14. 9. The semiconductor device of claim 8, wherein the lower waveguide of a first VCSEL emitter and the lower waveguide of a second VCSEL emitter adjacent to the first VCSEL emitter coherently couple the first VCSEL emitter to the second VCSEL emitter.

15. 9. The semiconductor device of claim 8, wherein the lower waveguide of a first VCSEL emitter and the lower waveguide of a second VCSEL emitter adjacent to the first VCSEL emitter phase couple the first VCSEL emitter to the second VCSEL emitter.

16. 1. A method of forming a semiconductor device, comprising: forming a bottom mirror on the top surface of the substrate; forming a lower waveguide on a top surface of the lower mirror, an inner portion of the lower waveguide having a greater effective refractive index than an outer portion of the lower waveguide; forming an active region over the lower waveguide; forming an upper waveguide over the active region, an inner portion of the upper waveguide having a lower effective refractive index than an outer portion of the upper waveguide; forming an upper mirror on the upper waveguide; wherein the inner portion of the upper waveguide has a larger lateral dimension than the inner portion of the lower waveguide.

17. 17. The method of claim 16, forming the bottom mirror includes growing alternating layers of a first semiconductor and a second semiconductor, the first semiconductor having a higher effective refractive index than the second semiconductor; forming the top mirror includes growing alternating layers of the first semiconductor and the second semiconductor; method.

18. 17. The method of claim 16, forming a bottom contact layer beneath the substrate; forming a top contact layer on the top mirror; wherein the active region is formed to emit light in response to an electrical bias applied between the bottom contact layer and the top contact layer.

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