Independent control of polarization orientation and optical mode of vertical cavity surface emitting laser

Abstract

The invention relates to independent control of polarization orientation and optical mode of a vertical cavity surface emitting laser. In some embodiments, a VCSEL includes a first cap layer and a second cap layer. The first cap layer includes a semiconductor material and is disposed over the confinement hole of the VCSEL. The second cap layer includes a dielectric material and is disposed over the confinement hole of the VCSEL. A polarizing filter structure is formed in the first cap layer. A mode filter structure is formed in the second cap layer.

Description

[0001] Cross-reference to related applications

[0002] This patent application claims priority to U.S. Patent Application No. 63 / 638,606, filed April 25, 2024, entitled “SINGLE MODE AND SINGLEPOLARIZED VERTICAL-CAVITY SUFACE-EMITTING LASERS”. The disclosure of that prior application is considered part of this patent application and is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to vertical cavity surface-emitting lasers (VCSELs) and the independent control of the polarization orientation and optical modes of VCSELs. Background Technology

[0004] Emitters may include vertically emitting devices, such as VCSELs. A VCSEL is a laser in which a laser beam is emitted in a direction perpendicular to the surface of the VCSEL (e.g., emitted vertically from the surface of the VCSEL). Multiple emitters may be arranged in an emitter array having a common substrate. Summary of the Invention

[0005] In some embodiments, a VCSEL includes a first capping layer and a second capping layer. The first capping layer includes a semiconductor material disposed over a limiting aperture of the VCSEL, and the second capping layer includes a dielectric material disposed over the limiting aperture of the VCSEL. A polarizing filter structure is formed in the first capping layer, and a mode filter structure is formed in the second capping layer.

[0006] In some embodiments, an optical component includes a plurality of VCSELs, wherein each VCSEL includes: a first capping layer; and a second capping layer, wherein: a polarizing filter structure is formed in the first capping layer, and a mode filter structure is formed in the second capping layer.

[0007] In some embodiments, a chip includes a plurality of VCSELs, wherein each VCSEL includes: a polarizing filter structure disposed over a limiting aperture of the VCSEL; and a mode filter structure disposed over the limiting aperture of the VCSEL. Attached Figure Description

[0008] Figure 1A-Figure 1B This is a diagram associated with an example implementation of VCSEL;

[0009] Figure 2 This is a diagram associated with the example optical device;

[0010] Figure 3 It is a diagram associated with the example chip; and

[0011] Figures 4A-4B Single-mode operation of a similarly configured VCSEL is shown. Detailed Implementation

[0012] The following exemplary embodiments will be described in detail with reference to the accompanying drawings. The same reference numerals in different drawings may identify the same or similar elements.

[0013] A VCSEL typically comprises two distributed Bragg reflector (DBR) mirrors arranged parallel to the wafer surface, with the active region positioned between the two DBR mirrors. The active region includes one or more quantum wells for laser generation. VCSELs are widely used in various applications, such as data communication, sensing, and optical interconnects, due to their superior advantages over other types of lasers. For example, VCSELs typically exhibit lower power consumption (e.g., operating a VCSEL requires significantly less power than other types of lasers, making them more energy-efficient and cost-effective), high-speed operation (e.g., making VCSELs ideal for data communication and other applications requiring fast signal transmission), narrow beam divergence (e.g., the narrow beam divergence of a VCSEL allows for high coupling efficiency with optical fibers and other components, making VCSELs easier to integrate into optical systems), and high reliability (e.g., VCSELs have a longer operating life and are less prone to failure compared to other types of lasers).

[0014] VCSELs can possess cylindrical symmetry and therefore do not have a preferred polarization orientation. Typically, this allows VCSELs to support combinations of modes emitting laser light in different polarization orientations. However, for many applications (such as data communication, optical systems requiring polarization-sensitive optics, spectroscopy, and 3D sensing), it is undesirable for VCSELs to emit laser light in different polarization orientations. For example, individual VCSELs may perform differently in the same application when emitting laser light in different polarization orientations. Another problem is that the polarization orientation of a VCSEL can spontaneously change based on VCSEL conditions (such as ambient temperature, current level, or package stress), making VCSEL performance unpredictable. For data communication (such as for polarization-sensitive optical links), polarization transitions under different modulation conditions can lead to high bit error rates (BER).

[0015] Furthermore, due to their large transverse cavity size or confinement aperture, VCSELs typically exhibit spatial multimodal behavior. The more modes a VCSEL supports, the more unstable the polarization state of each mode becomes. In some cases, single-mode operation in a VCSEL can be achieved using a smaller confinement aperture. However, this usually leads to reduced power and reliability of the VCSEL. It is also difficult to fabricate such a small confinement aperture.

[0016] Some embodiments described herein include a VCSEL. The VCSEL includes a first capping layer and a second capping layer, both disposed over a confinement aperture of the VCSEL (e.g., in a stacked manner). The first capping layer includes a polarization filter structure (e.g., comprising a grating) configured to support a single polarization orientation of a laser beam emitted by the VCSEL. The second capping layer includes a mode filter structure configured to support a reduced number of optical modes of the laser beam (e.g., a reduced number of spatial optical modes), such as a single optical mode (e.g., a single spatial optical mode).

[0017] In this way, VCSELs provide a consistent number of optical modes and a single polarization orientation for each optical mode. For example, a VCSEL can support single-mode and single polarization orientation. This can contribute to lower relative intensity noise (RIN) and improved photocurrent (LI) performance of the VCSEL (e.g., in terms of kinking behavior in the LI curve associated with the VCSEL). Furthermore, some embodiments described herein enable VCSEL performance uniformity without compromising the power and reliability of the VCSEL (e.g., compared to reducing the size of the confinement aperture).

[0018] Accordingly, in at least some cases, the VCSELs described herein are preferred VCSELs for data communication, optical systems requiring polarization-sensitive optics, spectroscopy, and 3D sensing, etc. For example, many of the VCSELs described herein can be configured to emit laser light with the same polarization orientation, and therefore exhibit consistent performance in the same applications. Furthermore, the performance of the VCSEL remains consistent even under varying or different conditions. Therefore, this can reduce BER (bit / earth error) for polarization-sensitive optical links associated with data communication, for example.

[0019] It is noteworthy that the polarization filter structure and mode filter structure described herein are formed in different layers of the VCSEL. Accordingly, each filter structure can be formed to have optimal characteristics. For example, the characteristics of the polarization filter structure (e.g., the etch depth of the polarization filter structure, the grating pitch of the polarization filter structure, the grating pattern of the polarization filter structure, the shape of the polarization filter structure, the orientation of the trenches of the polarization filter structure, and / or the size of the polarization filter structure) can suppress the polarization filter structure from supporting more than one polarization orientation. As another example, the characteristics of the mode filter structure (e.g., the etch depth of the mode filter structure, the size of the mode filter structure, and / or the shape of the mode filter structure 126) can reduce the number of optical modes supported by the mode filter structure. It is noteworthy that, by being formed in the respective capping layers, the polarization filter structure and the mode filter structure can be designed (or selected) independently. That is, the VCSEL can provide independent control over the polarization orientation and optical modes of the VCSEL.

[0020] In this way, both filter structures can be designed to provide optimal performance (e.g., optimal optical mode performance and optimal polarization orientation performance) that cannot be achieved otherwise. For example, a conventional VCSEL can use the same layer or structure to attempt to control the number of modes and polarization orientations, but the physical dimensions of that layer or structure are not optimal for both optical mode control and polarization orientation control (e.g., because it is limited to a single etch depth).

[0021] Figure 1A-Figure 1B This is a diagram associated with an example implementation 100 of VCSEL 102. In some implementations, VCSEL 102 may be included in a transmitter array (e.g., a VCSEL 102 array). In some implementations, such as Figure 1A-Figure 1B As shown, VCSEL 102 is a top-emitting transmitter. Alternatively, in some embodiments, VCSEL 102 may be a bottom-emitting transmitter (e.g., having a bottom-emitting transmitter with...). Figure 1A-Figure 1B A similar structure to the one shown, but modified to enable bottom emission. (As shown...) Figure 1A-Figure 1B As shown, VCSEL 102 may include a cavity comprising one or more active regions (referred to herein as cavity region 104), a confinement layer 106 forming a confinement aperture 108, a mirror structure 110, a first capping layer 112, an etch stop layer 114, a second capping layer 116, and / or a protective layer 118. Cavity region 104, confinement layer 106, mirror structure 110, first capping layer 112, etch stop layer 114, second capping layer 116, and protective layer 118 may be formed on a substrate, additional mirror structure, and / or one or more other layers and / or structures (not shown for clarity and ease of explanation). Figure 1A-Figure 1B(shown above).

[0022] Cavity region 104 includes one or more layers in which electrons and holes recombine to emit light and define the emission wavelength range of VCSEL 102. For example, cavity region 104 may include one or more active regions in the form of one or more quantum wells (QWs). In some embodiments, cavity region 104 may include one or more cavity spacer layers (e.g., to allow sufficient space for epitaxial growth to vary the composition or temperature). In some embodiments, one or more cavity spacer layers may reduce strain between the active regions of cavity region 104 and / or may alleviate thermal problems in the laser operation of VCSEL 102. In some embodiments, one or more cavity spacer layers may include oxide layers. In some embodiments, cavity region 104 includes a set of layers grown using metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or another technique. In some embodiments, a plurality of cavity regions 104 may be included within the VCSEL structure.

[0023] The optical thickness of cavity region 104 (including one or more active regions and any cavity spacer layers), confinement layer 106, mirror structure 110, first capping layer 112, etch stop layer 114 and / or second capping layer 116 (and any additional layers or structures formed thereon on cavity region 104, such as a substrate and another mirror structure) can define the resonant cavity wavelength of VCSEL 102, which can be designed to be within the emission wavelength range of cavity region 104 to enable laser emission. In some embodiments, the wavelength range of VCSEL 102 can be in the range of about 940 nanometers (nm) to about 1380 nm.

[0024] The confinement layer 106 is a layer that provides optical and / or electrical confinement to the VCSEL 102. In some embodiments, the confinement layer 106 enhances carrier and mode confinement of the VCSEL 102, and thus can improve the performance of the VCSEL 102. In some embodiments, the confinement layer 106 is located on, below, or within the cavity region 104. In some embodiments, one or more spacer layers or mirror layers (e.g., one or more DBRs) may be present between the confinement layer 106 and the cavity region 104. In some embodiments, such as Figure 1A-Figure 1B As shown, the confinement layer 106 is located above the cavity region 104, such that the confinement layer 106 is on the side of the cavity region 104 closer to the mirror structure 110 (i.e., on the non-substrate side of the cavity region 104).

[0025] In some embodiments, the confinement layer 106 at least partially comprises an oxide layer formed by the oxidation of one or more epitaxial layers of the VCSEL 102. For example, the confinement layer 106 may be an alumina (Al2O3) layer formed by the oxidation of an epitaxial layer (e.g., an AlGaAs layer, an AlAs layer, etc.). In some embodiments, the thickness of the confinement layer 106 may range from about 0.007 micrometers (μm) to about 0.04 μm (e.g., 0.02 μm). In some embodiments, in addition to the confinement layer 106, the VCSEL 102 may also include one or more other types of structures or layers (such as implanted passivation structures, mesa isolation structures, trench recess isolation structures, buried tunnel junctions, etc.) that provide current confinement. Additionally or alternatively, other types of structures or layers for providing current confinement may be included in or integrated with the confinement layer 106.

[0026] In some embodiments, the confinement layer 106 defines a confinement aperture 108. Therefore, in some embodiments, the confinement aperture 108 is an optically active aperture defined by the confinement layer 106. In some embodiments, the size 120 of the confinement aperture 108 (e.g., width in a given direction) is in the range of about 1 μm to about 300 μm (e.g., 5 μm or 8 μm). In some embodiments, as described above, the confinement aperture 108 can be formed by oxidation (e.g., when the confinement layer 106 includes an oxide layer), and therefore the confinement aperture 108 can be referred to as an oxide aperture. Additionally or alternatively, the confinement aperture 108 can be formed by other means, such as by implantation, diffusion, regrowth (e.g., using a high-resistivity layer, current-blocking layer, tunnel junction, etc.), or air gaps, etc.

[0027] The mirror structure 110 is a reflector (e.g., a top reflector) of the optical resonator of the VCSEL 102. For example, the mirror structure 110 may include multiple DBR pairs or another type of mirror structure. In some embodiments, the mirror structure 110 is formed of a p-type material. Therefore, in some embodiments, the mirror structure 110 includes multiple p-type DBR pairs. Alternatively, in some embodiments, the mirror structure 110 may be formed of an n-type material. In some embodiments, the mirror structure 110 may have a thickness in the range of about 1 μm to about 6 μm (e.g., 3 μm). In some embodiments, the mirror structure 110 includes a set of layers (e.g., an AlGaAs layer) grown using MOCVD, MBE, or another technique. In some embodiments, the mirror structure 110 is grown on or above the cavity region 104.

[0028] In some embodiments, the first capping layer 112 may include a polarizing filter structure 122 (e.g., formed within the first capping layer 112). The polarizing filter structure 122 may include, for example, a grating structure (e.g., including a one-dimensional grating, or one or more other types of gratings). The polarizing filter structure 122 may be disposed within the first capping layer 112 (e.g., completely disposed such that the polarizing filter structure 122 has no portion that does not extend beyond the first capping layer 112). The polarizing filter structure 122 may be associated with the polarization of the output light (e.g., a laser beam) emitted by the VCSEL 102. For example, the polarizing filter structure 122 may introduce polarization dependence into the reflectivity and / or transmittance of the VCSEL 102, with the effect of suppressing one of the two orthogonal polarization orientations of the light (e.g., causing the light emitted by the VCSEL 102 to have a single polarization orientation).

[0029] The polarization filter structure 122 (e.g., when the polarization filter structure 122 includes a grating structure) can generate anisotropic reflectivity, or in other words, generate different reflectivities for transverse electric (TE) and transverse magnetic (TM) polarization. The polarization state with lower reflectivity becomes relatively more lossy and requires a higher threshold current. Ultimately, the polarization state with lower reflectivity either does not enter a stimulated emission state at the operating current or emits laser light near the threshold at low power. The greater the power difference between the two polarization states, the stronger the polarization selectivity (i.e., the larger the polarization extinction ratio (PER)). Since the presence of the polarization filter structure 122 alters the reflectivity, performance can be expected to be adversely affected. In some embodiments, the polarization filter structure 122 of the VCSEL 102 can be designed using rigorous coupled-wave analysis methods to optimize for minimizing adverse effects on performance (e.g., threshold current or slope efficiency). In some embodiments, the polarization filter structure 122 reduces or eliminates polarization switching in the VCSEL 102 by achieving a single dominant polarization state. As further described herein, in some embodiments, using the etch stop layer 114 to control the depth of the polarizing filter structure 122 enables a single dominant polarization state to be achieved in the VCSEL 102 (e.g., the polarizing filter structure 122 may support a single polarization orientation). This may result in the VCSEL 102 supporting a single polarization orientation. In some embodiments, the polarizing filter structure 122 may also be associated with an increase in reflectivity on the side of the VCSEL 102 that includes the mirror structure 110.

[0030] In some embodiments, the polarizing filter structure 122 can be formed by etching the first capping layer 112. In some embodiments, the polarizing filter structure 122 has a first etching depth 124 and a grating pitch (or period), which is on the order of the wavelength of the VCSEL 102 or an order of magnitude lower than the wavelength of the VCSEL 102. In some embodiments, such as when the polarizing filter structure 122 includes a grating structure, the polarizing filter structure 122 can have a periodic or aperiodic pattern. Additionally or alternatively, the grating structure of the polarizing filter structure 122 can have various shapes (such as rectangular, square, triangular, sinusoidal, etc.) depending on the needs of a given application. In some embodiments, the polarizing filter structure 122 can be formed using photolithography, deep ultraviolet (UV) lithography, nanoimprint lithography, or electron beam lithography. In some embodiments, the polarizing filter structure 122 has subwavelength scale feature dimensions. In some embodiments, as determined by design (e.g., grating design), the polarization provided by the polarizing filter structure 122 can be in a direction parallel to or perpendicular to the grooves of the polarizing filter structure 122. It is noteworthy that the polarizing filter structure 122 can be used for any shape of the limiting aperture 108, such as a circular limiting aperture 108 or an asymmetric limiting aperture 108. Furthermore, in some embodiments, the polarizing filter structure 122 can completely cover the VCSEL 102. Alternatively, in some embodiments, the shape of the polarizing filter structure 122 (e.g., the shape of the boundary of the polarizing filter structure 122, the shape of the outer edge of the polarizing filter structure 122, or the shape of another similar characteristic of the polarizing filter structure 122) can match the shape of the limiting aperture 108. In some embodiments, the polarizing filter structure 122 can have the same or similar dimensions as the limiting aperture 108. Alternatively, an overlapping (within tolerance) or slightly larger polarizing filter structure 122 than the limiting aperture 108 can be used.

[0031] In some embodiments, the first cover layer 112 is located above (i.e., above, such as) the mirror structure 110, the second cover layer 116, the protective layer 118, or the limiting hole 108. Figure 1A-Figure 1B The polarizing filter structure 122 may be on, below, or in the middle of at least one of any other layer or structure (as shown). Accordingly, the polarizing filter structure 122 may be on (i.e., above, such as) the mirror structure 110, the second capping layer 116, the protective layer 118, or the limiting aperture 108. Figure 1A-Figure 1B Above, below, or in the middle of at least one of any other layer or structure (as shown).

[0032] The etch stop layer 114 is a layer associated with controlling one or more parameters of the polarizing filter structure 122 during etching of the polarizing filter structure 122. That is, the etch stop layer 114 is a layer associated with controlling the etching of the first capping layer 112 during the formation of the polarizing filter structure 122 in the first capping layer 112. In some embodiments, the etch stop layer 114 is incorporated into the mirror structure 110 of the VCSEL 102. In some embodiments, the etch stop layer 114 is incorporated into the first capping layer 112, such as... Figure 1A As shown. In some embodiments, the first capping layer 112 is disposed on the etch stop layer 114, such as... Figure 1B As shown.

[0033] The first capping layer 112 may include a semiconductor material (such as GaAs and / or AlGaAs). In some embodiments, the thickness of the first capping layer 112 may be in the range of about 0.2 μm to about 0.5 μm (such as 0.3 μm). In some embodiments, the etch stop layer 114 includes a material having high etch selectivity to the first capping layer 112. For example, the etch stop layer 114 may include a material having an etch selectivity greater than 10 (i.e., the etch rate of the first capping layer 112 is 10 times that of the etch stop layer 114). In some embodiments, the etch stop layer 114 may include a material having an etch selectivity of at least 100. In some embodiments, the etch stop layer 114 may include indium gallium phosphide (InGaP) (e.g., when the substrate of the VCSEL 102 includes GaAs). In some embodiments, the thickness of the etch stop layer 114 is in the range of about 10 nanometers (nm) to about 100 nm (such as 20 nm).

[0034] The second capping layer 116 may include, for example, a dielectric material (such as silicon nitride (SiN)). X (e.g., silicon dioxide (SiO2), polymer dielectric, or another type of insulating material). In some embodiments, the thickness of the second capping layer 116 is approximately equal to a multiple of (λ / 2) × n, where λ is the design wavelength of the VCSEL 102 and n is the refractive index of the material of the second capping layer 116.

[0035] When the second cover layer 116 is disposed on top of the first cover layer 112 (e.g., as Figure 1A As shown), the first capping layer 112 and the second capping layer 116 may respectively comprise a semiconductor material and a dielectric material, as described herein. Alternatively, when the first capping layer 112 is disposed over the second capping layer 116 (e.g., as shown), Figure 1B As shown), the first capping layer 112 and the second capping layer 116 may respectively include dielectric material and semiconductor material.

[0036] In some embodiments, the second capping layer 116 may include a pattern filter structure 126 (e.g., formed within the second capping layer 116). The pattern filter structure 126 may include, for example, a stepped structure (e.g., having at least a bottom step and a top step). The pattern filter structure 126 may be disposed within the second capping layer 116 (e.g., completely disposed such that the pattern filter structure 126 does not extend beyond the second capping layer 116). Additionally or alternatively, depending on the needs of a given application, the pattern filter structure 126 (e.g., the top step of the stepped structure) may have various shapes (such as rectangular, square, triangular, circular, etc.). In some embodiments, the pattern filter structure 126 may be formed using photolithography, deep ultraviolet lithography, or nanoimprint lithography, etc.

[0037] In some embodiments, the mode filter structure 126 can be formed by etching the second capping layer 116. The mode filter structure 126 (e.g., the top step of a stepped structure) may have a second etching depth 128 and / or a dimension 130 (e.g., width, diameter, or another dimensional measurement in a given direction). Accordingly, the mode filter structure 126 may be configured to reduce the number of optical modes (e.g., the number of spatial optical modes) supported by the mode filter structure 126 (and therefore by the VCSEL 102) due to factors such as the second etching depth 128 and / or the dimension 130 of the mode filter structure 126.

[0038] Accordingly, the mode filter structure 126 (e.g., due to the second etch depth 128 of the mode filter structure 126 and / or the size 130 of the mode filter structure 126) can be configured to support a single optical mode (e.g., a single spatial optical mode). This may result in the VCSEL 102 being a single-mode (SM) VCSEL (e.g., emitting a laser beam with only one optical mode, such as a basic optical mode). Alternatively, the mode filter structure 126 (e.g., due to the second etch depth 128 of the mode filter structure 126 and / or the size 130 of the mode filter structure 126) can be configured to support one or more optical modes (e.g., by allowing laser emission of one or more optical modes and / or by suppressing laser emission of one or more other optical modes). This may result in the VCSEL 102 being a reduced-mode (RM) VCSEL (e.g., emitting a laser beam with a reduced number of optical modes, such as a basic optical mode and one or more higher-order optical modes).

[0039] It is worth noting that the pattern filter structure 126 can be used for any shape of the limiting aperture 108, such as a circular limiting aperture 108 or an asymmetrical limiting aperture 108. Furthermore, in some embodiments, the shape of the pattern filter structure 126 can match the shape of the limiting aperture 108. In some embodiments, the size 130 of the pattern filter structure 126 can be the same as or similar to the size 120 of the limiting aperture 108. Alternatively, an overlapping (within tolerances) pattern filter structure 126 that is slightly larger or smaller than the limiting aperture 108 can be used.

[0040] The protective layer 118 may include layers that serve as a protective passivation layer and / or reflective layer. For example, the protective layer 118 may include one or more sublayers (e.g., dielectric passivation layer and / or reflective layer, SiO2 layer, Si3N4 layer, Al2O3 layer or other layers) deposited (e.g. by chemical vapor deposition, atomic layer deposition or other techniques) on one or more other layers of the VCSEL 102.

[0041] like Figure 1A-Figure 1B As shown, a first capping layer 112 and a second capping layer 116 can be disposed over the limiting aperture 108 (e.g., in a stacked manner). Correspondingly, a polarizing filter structure 122 (e.g., formed in the first capping layer 112) and a mode filter structure 126 (e.g., formed in the second capping layer 116) can be disposed over the limiting aperture 108 (e.g., in a stacked manner). In some embodiments, such as Figure 1A As shown, the first capping layer 112 can be located between the limiting aperture 108 and the second capping layer 116, and therefore the polarizing filter structure 122 can be disposed between the limiting aperture 108 and the mode filter structure 126. Alternatively, as Figure 1B As shown, the second capping layer 116 can be located between the limiting aperture 108 and the first capping layer 112, and therefore the mode filter structure 126 can be disposed between the limiting aperture 108 and the polarizing filter structure 122. Accordingly, in any case, such as Figure 1A-Figure 1B As further shown, the first distance between the limiting hole 108 and the etch stop layer 114 (e.g., disposed above the limiting hole 108) may be less than at least one of the second distance between the limiting hole 108 and the first capping layer 112 (and between the limiting hole 108 and the polarizing filter structure 122) and the third distance between the limiting hole 108 and the second capping layer 116 (and between the limiting hole 108 and the mode filter structure 126).

[0042] In some implementations, the first etch depth 124 of the polarizing filter structure 122 and the second etch depth 128 of the mode filter structure 126 can be different (e.g., different from each other). For example, the first etch depth 124, as determined by design, can cause the polarizing filter structure 122 to suppress orthogonal polarization orientations of light and thus support only a single polarization orientation. This may result in the VCSEL 102 supporting a single polarization orientation. As another example, the second etch depth 128, as determined by design, can cause the mode filter structure 126 to reduce the number of optical modes supported by the mode filter structure 126 (and therefore by the VCSEL 102). This may result in the VCSEL 102 being an SM VCSEL or an RM VCSEL.

[0043] In some embodiments, the characteristics of the polarization filter structure 122 (e.g., the first etch depth 124 of the polarization filter structure, the grating pitch of the polarization filter structure 122, the pattern of the grating of the polarization filter structure 122, the shape of the polarization filter structure 122, the orientation of the trenches of the polarization filter structure 122, and / or the size of the polarization filter structure 122) and the characteristics of the mode filter structure 126 (e.g., the second etch depth 128 of the mode filter structure 126, the size 130 of the mode filter structure 126, and / or the shape of the mode filter structure 126) are independently determined (or independently selected) to provide optimal performance for the polarization filter structure 122 and the mode filter structure 126, respectively. That is, the characteristics of the polarization filter structure 122 (e.g., the first etch depth 124 and / or other characteristics) can be designed to provide optimal configuration of the polarization filter structure 122 (e.g., supporting a single polarization orientation of the laser beam emitted by the VCSEL 102). Furthermore, the characteristics of the mode filter structure 126 (e.g., the second etch depth 128, size 130, and / or other characteristics) can be designed to provide an optimal configuration of the mode filter structure 126 (e.g., supporting a reduced number of optical modes, such as a single optical mode). In this way, some embodiments described herein can independently control the polarization orientation (e.g., via the configuration of the polarization filter structure 122) and optical mode (e.g., via the configuration of the mode filter structure 126) of the VCSEL 102. Therefore, in some cases, the corresponding characteristics of the polarization filter structure 122 and the mode filter structure 126 (e.g., the first etch depth 124 and the second etch depth 128) can be different, or in other cases they can be the same.

[0044] Figure 1A-Figure 1B The number, arrangement, thickness, order, and symmetry of the layers shown are for illustrative purposes only. In practice, the actual arrangement will differ from the actual arrangement. Figure 1A-Figure 1BCompared to the examples shown, VCSEL 102 may include additional layers, fewer layers, different layers, differently constructed layers, or differently arranged layers. For example, as described above, VCSEL 102 may be a bottom-emitting VCSEL in some embodiments, and with... Figure 1A-Figure 1B Structures similar to those shown can be used for bottom emission with appropriate modifications to support bottom emission (e.g., the output aperture can be formed at the bottom of the VCSEL instead of the top of the VCSEL). Additionally or alternatively, a set of layers (e.g., one or more layers) of VCSEL 102 can perform one or more functions described as being performed by another set of layers of VCSEL 102, and any layer can include more than one layer. While some embodiments described herein are directed to a single VCSEL (e.g., VCSEL 102), some embodiments include multiple VCSELs (e.g., multiple VCSEL 102).

[0045] Figure 2 This is a diagram associated with example optical device 200. Example optical device 200 can be, for example, an optical communication device, an optical sensing device, an optical interconnect device, an optical structured light device, or another type of optical device. Optical device 200 may include optical assembly 202, which may include one or more VCSELs 102 (in... Figure 2 The image shows three VCSELs 102, which may be arranged in a pattern (e.g., a one-dimensional array, a two-dimensional array, or another type of pattern) within the optical assembly 202.

[0046] One or more VCSELs 102 can be configured to emit corresponding laser beams, such as those coupled to (e.g., into) the input end of an optical fiber (e.g., single-mode or multimode fiber). Alternatively, one or more VCSELs can be coupled to an optical component or optical system (e.g., a lens or lens system). The corresponding laser beams can be associated with the same spectral range. That is, each VCSEL 102 can be configured to emit a laser beam associated with a specific spectral range. For example, each VCSEL 102 can be configured to emit a laser beam associated with a spectral range having a center wavelength of 850 nm.

[0047] Furthermore, each VCSEL 102 can be configured to emit a laser beam having one or more optical modes and a single polarization orientation. For example, each VCSEL 102 may include a polarization filter structure 122 supporting a single polarization orientation (e.g., formed in a first capping layer 112) and a mode filter structure 126 supporting one or more optical modes (e.g., formed in a second capping layer 116). The polarization filter structure 122 and the mode filter structure 126 can be formed in different layers and therefore can be independent of each other. Accordingly, the polarization filter structure 122 and the mode filter structure 126 can each be optimally configured, which facilitates independent control of the polarization orientation and optical mode of the VCSEL 102.

[0048] As mentioned above, Figure 2 Provided as an example. Other examples may be found with reference to [the example provided]. Figure 2 The differences mentioned.

[0049] Figure 3 This is a diagram associated with example wafer 300. Wafer 300 can be used to manufacture integrated circuits, chips, semiconductor lasers, etc. For example, wafer 300 can be used to form multiple VCSELs 102 (e.g., multiple VCSELs 102 are formed on a uniform substrate, and then the VCSELs 102 can be individualized or an array of VCSELs 102 can be formed using a dicing process).

[0050] like Figure 3 As shown, multiple VCSELs 102 can be formed on the surface (e.g., the top surface) of wafer 300. As described elsewhere herein, each VCSEL 102 can be configured to emit a laser beam having one or more optical modes and a single polarization orientation. For example, each VCSEL 102 may include a polarization filter structure 122 supporting a single polarization orientation (e.g., formed in a first capping layer 112) and a mode filter structure 126 supporting one or more optical modes (e.g., formed in a second capping layer 116). The polarization filter structure 122 and the mode filter structure 126 can be formed in different layers and therefore can be independent of each other. Accordingly, the polarization filter structure 122 and the mode filter structure 126 can each be optimally configured, which facilitates independent control of the polarization orientation and optical mode of the VCSEL 102.

[0051] As mentioned above, Figure 3 Provided as an example. Other examples may be found with reference to [the example provided]. Figure 3 The differences mentioned.

[0052] Figures 4A-4B Single-mode operation of a VCSEL with a similar configuration under high bias current is shown. Figure 4AThe optical spectrum of a VCSEL (e.g., operating at 8 mA) without any mode filter structure is shown. Here, the two modes (e.g., two nearly equal modes) of the laser beam emitted by the VCSEL compete with each other. Accordingly, as Figure 4A As shown in the illustration, in a one-dimensional (1D) far-field cross-section, the beam profile of the laser beam has a distinct bulge and differs from that of a Gaussian beam profile.

[0053] Figure 4B The optical spectrum of the VCSEL 102 described herein (e.g., operating at 8 mA with a 5.5 μm confinement aperture 108) is shown. This VCSEL 102 includes a second capping layer 116 and a mode filter structure 126 (e.g., size 130 of 6.0 μm). Here, the single-mode operation of the VCSEL 102 is demonstrated as a side-mode suppression ratio (SMSR) of 36 dB or approximately. Accordingly, as... Figure 4B As shown in the illustration, in a 1D far-field cross-section, the beam profile of the laser beam emitted by the VCSEL 102 is similar to that of a Gaussian beam.

[0054] As mentioned above, Figures 4A-4B This is provided as an example only. Other examples may be found in relation to [the example provided]. Figures 4A-4B The differences mentioned.

[0055] The foregoing disclosure provides illustrations and descriptions, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations can be made based on the foregoing disclosure, or modifications and variations can be obtained from the practice of the embodiments. Furthermore, any of the embodiments described herein can be combined, unless the foregoing disclosure expressly provides a reason why one or more embodiments cannot be combined.

[0056] As used in this article, depending on the context, satisfying the threshold can mean a value greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, etc.

[0057] Although specific combinations of features are listed in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various embodiments. In fact, many of these features can be combined in ways not specifically listed in the claims and / or not disclosed in the specification. While each dependent claim listed below may directly depend on only one claim, the disclosure of various embodiments includes combinations of each dependent claim with each other claim in the claim set. As used herein, the phrase “at least one of” in the list of referenced items refers to any combination of these items, including single members. For example, “at least one of a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as combinations of multiple identical items.

[0058] Unless explicitly stated otherwise, no element, action, or instruction used herein should be construed as critical or necessary. Furthermore, as used herein, the articles “a” and “an” are intended to include one or more items and are interchangeable with “one or more.” Similarly, as used herein, the article “the” is intended to include one or more items referenced in combination with the article “the” and is interchangeable with “one or more.” Furthermore, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items) and is interchangeable with “one or more.” If only one item is referred to, the phrase “only one” or similar language is used. Furthermore, as used herein, the terms “has,” “have,” “having,” etc., are intended to be open-ended terms. Additionally, unless explicitly stated otherwise, the term “based on” is intended to mean “at least partially based on.” Furthermore, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and / or” unless otherwise explicitly stated (e.g., if used in conjunction with “either of” or “only one of”). Additionally, for ease of description, spatially relative terms (such as “below,” “lower,” “above,” “upper,” etc.) may be used herein to describe the relationship of an element or feature to other elements or features shown in the figures. Spatially relative terms are intended to cover different orientations of devices, apparatuses, and / or elements in use or operation, in addition to the orientations depicted in the figures. The device may be oriented in other ways (rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein may be interpreted accordingly.

Claims

1. A vertical-cavity surface-emitting laser (VCSEL), comprising: The first capping layer includes a semiconductor material disposed on the limiting aperture of the VCSEL; as well as The second capping layer comprises a dielectric material disposed above the limiting aperture of the VCSEL, wherein: A polarizing filter structure is formed in the first capping layer, and The pattern filter structure is formed in the second capping layer.

2. The VCSEL according to claim 1, wherein the polarizing filter structure includes a grating structure.

3. The VCSEL according to claim 1, wherein the mode filter structure includes a stepped structure.

4. The VCSEL according to claim 1, wherein: The polarizing filter structure is associated with the first etching depth; The pattern filter structure is associated with the second etching depth; and The first etching depth is different from the second etching depth.

5. The VCSEL according to claim 1, wherein: The first capping layer and the second capping layer are stacked on top of the limiting hole of the VCSEL; and The first cover layer is between the limiting hole and the second cover layer.

6. The VCSEL according to claim 1, wherein: The first capping layer and the second capping layer are stacked on top of the limiting hole of the VCSEL; and The second cover layer is located between the limiting hole and the first cover layer.

7. The VCSEL of claim 1, wherein the VCSEL further comprises an etch stop layer, wherein: The etch stop layer is disposed above the limiting hole; and The first distance between the limiting hole and the etch stop layer is less than at least one of the second distance between the limiting hole and the first capping layer or the third distance between the limiting hole and the second capping layer.

8. The VCSEL of claim 1, wherein the VCSEL supports a single spatial optical mode and a single polarization orientation.

9. An optical component, comprising: Multiple vertical-cavity surface-emitting lasers (VCSELs), wherein each VCSEL comprises: First cap layer; and The second cover layer, wherein: A polarizing filter structure is formed in the first capping layer, and The pattern filter structure is formed in the second capping layer.

10. The optical component of claim 9, wherein the polarizing filter structure comprises a grating structure.

11. The optical component of claim 9, wherein the mode filter structure comprises a stepped structure.

12. The optical component according to claim 9, wherein: The polarizing filter structure is associated with the first etching depth; The pattern filter structure is associated with the second etching depth; and The first etching depth is different from the second etching depth.

13. The optical component according to claim 9, wherein: The first capping layer and the second capping layer are stacked on the limiting hole of the VCSEL; as well as The first cover layer is between the limiting hole and the second cover layer.

14. The optical component according to claim 9, wherein: The first capping layer and the second capping layer are stacked on the limiting hole of the VCSEL; as well as The second cover layer is located between the limiting hole and the first cover layer.

15. The optical assembly of claim 9, wherein each VCSEL further comprises an etch stop layer, wherein: The first distance between the limiting hole of the VCSEL and the etch stop layer is less than at least one of the second distance between the limiting hole and the first capping layer or the third distance between the limiting hole and the second capping layer.

16. A chip, comprising: Multiple vertical-cavity surface-emitting lasers (VCSELs), wherein each VCSEL comprises: A polarizing filter structure is disposed above the limiting aperture of the VCSEL; and A pattern filter structure is disposed above the limiting aperture of the VCSEL.

17. The wafer of claim 16, wherein the polarizing filter structure comprises a grating structure.

18. The wafer of claim 16, wherein the mode filter structure comprises a stepped structure.

19. The wafer according to claim 16, wherein: The polarizing filter structure is associated with the first etching depth; The pattern filter structure is associated with the second etching depth; and The first etching depth is different from the second etching depth.

20. The wafer of claim 16, wherein each VCSEL further comprises an etch stop layer, wherein: The etch stop layer is disposed above the limiting hole; and The first distance between the limiting aperture and the etch stop layer is less than at least one of the second distance between the limiting aperture and the polarizing filter structure or the third distance between the limiting aperture and the mode filter structure.

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