Laser with a composite cavity of two semiconductors
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- II VI DELAWARE INC
- Filing Date
- 2025-02-17
- Publication Date
- 2026-07-31
Smart Images
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Abstract
Description
Technical Field
[0001]
[0001] This application is a non-provisional application and claims the benefit of U.S. Patent Application No. 63 / 389,468, filed on Jul. 15, 2022, the entire contents of which are incorporated herein by reference.
[0002] This disclosure generally relates to laser devices.
Background Art
[0003]
[0002] A vertical-cavity surface-emitting laser (VCSEL) has a laser cavity sandwiched between two mirror stacks that define it. A VCSEL is typically fabricated on a semiconductor substrate (often a GaAs or InP substrate), with the lower mirror stack formed on the upper surface of the substrate, and then covered by the laser cavity and the upper mirror stack. Each mirror stack includes a number of epitaxial layers with alternating refractive index values (e.g., alternating between "high" and "low" refractive index values). The cavity region itself includes an active region, which can be formed, for example, by one or more quantum well structures. When light passes from a layer of one refractive index to the other, a portion of the light is reflected, creating a diffraction Bragg reflector (DBR) structure. Using a sufficient number of alternating layers, a high percentage of the light is reflected, creating a standing wave pattern throughout the cavity.
Summary of the Invention
[0004]
[0003] A laser having a composite cavity of two semiconductors is illustrated and / or described in relation to at least one of the drawings and more fully described in the claims.
[0004] These and other advantages, aspects, and novel features of this disclosure, as well as details of the illustrated embodiments, will be more fully understood from the following description and the drawings.
Brief Description of the Drawings
[0005]
[0005] Various features and advantages of this disclosure can be better understood by referring to the following detailed description relating to the accompanying drawings, where similar reference numerals indicate similar structural elements. [Figure 1]
[0006] This shows a cross-sectional view of the vertical coupler portion of a laser, which has a composite cavity of two semiconductors. [Figure 2]
[0007] Figure 1 shows a plan view of the laser, which has a composite cavity of two semiconductors. [Figure 3]
[0008] Figure 1 shows a side view of the laser, which has a composite cavity of two semiconductors. [Modes for carrying out the invention]
[0006]
[0009] The following description illustrates various aspects of the Disclosure by providing examples. Such examples are non-limiting, and therefore the scope of the various aspects of the Disclosure should not be limited by any particular feature of the examples provided. In the following description, the phrases “for example” and “exemplary” are non-limiting and are generally synonymous with “for example, and not limited to these examples,” and “for example, and not limited to these examples.”
[0007]
[0010] When used in this specification, "and / or" means any one or more items in the list connected by "and / or". For example, "x and / or y" means any of the three elements in the set of three {(x), (y), (x, y)}. It means an element. In other words, "x and / or y" means "one or both of x and y". As another example, "x, y and / or z" means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and / or z" means "one or more of x, y, and z".
[0008]
[0011] The terms used in this specification are for illustrative purposes only and are not intended to limit the disclosure. Where used in this specification, the singular form is intended to include the plural form unless the context clearly indicates otherwise. It should be further understood that where used in this specification, terms such as “equipment,” “includes,” “possess,” “contains,” “have,” and “possess” identify the presence of the described feature, integer, step, action, element, and / or component, but do not exclude the presence or addition of one or more other features, integers, steps, actions, elements, components, and / or groups thereof.
[0009]
[0012] In this specification, terms such as "first," "second," etc., may be used to describe various elements, but it should be understood that these elements should not be limited by these terms. These terms are used only to distinguish one element from another. Therefore, for example, the first element, first component, or first part described later may be referred to as the second element, second component, or second part, to the extent that this disclosure does not depart from the teachings of this disclosure. Similarly, various spatial terms, such as "top," "bottom," and "side," may be used to distinguish one element from another in a relative manner. However, it should be understood that components may be oriented in different ways. For example, a semiconductor device or package may be oriented laterally, to the extent that this disclosure does not depart from the teachings of this disclosure, such that its "top" surface is horizontal and its "side" surface is vertical.
[0010]
[0013] In the drawings, the thickness or size of layers, regions, and / or components may be exaggerated for clarity. Therefore, the scope of this disclosure should not be limited by such thickness or size. In addition, in the drawings, similar reference numerals may refer to similar elements throughout the consideration. Numbered elements with an apostrophe (') may be analogous to correspondingly numbered elements without an apostrophe.
[0011]
[0014] Unless otherwise specified, the term "combined" can be used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements. For example, when element A is combined with element B, element A can be in direct contact with element B or indirectly connected to element B by an intervening element C. Similarly, the terms "over" or "on" can be used to describe two elements that are in direct contact with each other or two elements that are indirectly connected by one or more other elements.
[0012]
[0015] A composite cavity laser (CCL) includes a composite laser cavity consisting of cavities made of two semiconductor materials. A CCL may be fabricated using a pair of two semiconductor structures, where the upper part of the cavity is formed via a superstructure comprising a semiconductor material with a narrow bandgap energy (e.g., GaAs or InP), and the lower part of the cavity is formed via a substructure comprising a semiconductor material with a wide bandgap energy (e.g., SiC, AlN, or diamond). The cavity portions may be coupled together via a coupler (e.g., a vertical lattice coupler (VGC) or an evanescent taper coupler (ETC)). The upper part of the cavity may provide gain and distributed mirrors (e.g., lattice portions forming a distributed feedback structure or a distributed Bragg reflector structure) for the active laser action of the narrow bandgap semiconductor. The coupler is generated by the upper part of the cavity. Laser light or other optical energy can be guided into the lower part of the cavity. The lower part of the cavity can provide a lower-loss waveguide to the output facet of the substructure. The upper laser portion of the CCL can be formed, for example, by one or more quantum well structures.
[0013]
[0016] Figures 1 to 3 illustrate embodiments of the laser 10. The laser 10 may be implemented as a composite cavity laser (CCL), in which two semiconductor structures 100 and 200 having semiconductor materials with different band gaps are integrated together. In particular, the laser 10 may include an upper semiconductor structure 100 that provides an upper cavity 110 formed using a first semiconductor material, and a lower semiconductor structure 200 that provides a lower cavity 210 formed using a second semiconductor material having a wider band gap than the first semiconductor material.
[0014]
[0017] The upper semiconductor structure 100 may include an upper surface 101 of the upper structure, a lower surface 102 of the upper structure, and a side surface 103 of the upper structure between the upper surface 101 and the lower surface 102 of the upper structure. Similarly, the lower semiconductor structure 200 may include an upper surface 201 of the lower structure, a lower surface 202 of the lower structure, and a side surface 203 of the lower structure between the upper surface 201 and the lower surface 202 of the lower structure.
[0015]
[0018] The upper cavity 110 of the upper semiconductor structure 100 may be formed from a first semiconductor material, or the first semiconductor substrate may have a first bandgap. The lower cavity 210 of the lower semiconductor structure 200 may be formed from a second semiconductor material, or from a second semiconductor substrate having a second bandgap that is larger or wider than the first bandgap. Due to such differences in bandgap, the upper semiconductor structure 100 may be referred to in this specification as a narrow bandgap (NBG) structure 100, and the lower semiconductor structure 200 may be referred to in this specification as a wide bandgap (WBG) structure 200. In operation, the NBG structure 100 may provide gain, laser processing, and vertical coupling functions. The WBG structure 200 may provide cooling, waveguide, and photonic functions.
[0016]
[0019] As shown, the NBG structure 100 may comprise an upper waveguide 120 along the lower surface 102 of the NBG structure 100. The upper waveguide 120 may include one or more laser structures, such as a distributed Bragg reflector (DBR) structure or a distributed feedback (DFB) structure. As depicted, the upper waveguide 120 comprises a DBR structure 130 between a first contact 140 (e.g., n-contact) and a second contact 150 (e.g., p-contact). The upper waveguide 120 of the NBG structure 100 may further comprise a DFB structure 160 between the DBR structure 130 of the upper waveguide 120 and a coupler 170. The NBG structure 100 may further comprise a dielectric 180 enclosing the upper waveguide 120 and the contacts 140, 150. As shown, the dielectric 180 may provide and / or define the upper surface 101 and the side surface 103 of the superstructure.
[0017]
[0020] The WBG structure 200 may include a lower waveguide 220 along the upper surface of the WBG structure 200. The lower waveguide 220 may be embedded within the upper surface of the lower semiconductor structure 200. The WBG structure 200 may also include an optional DBR structure 230 between the lower waveguide 220 and the output facet 240 of the WBG structure 200.
[0018]
[0021] As shown, the lower surface 102 of the superstructure may be coupled to the upper surface 201 of the substructure, formed on the upper surface 201 of the substructure, or engaged with the upper surface 201 of the substructure. Furthermore, the upper waveguide 120 may be positioned on the lower waveguide 220 of the WBG structure 200 such that the first portion 190 of the upper waveguide 120 overlaps perpendicularly with the second portion 290 of the lower waveguide 220.
[0019]
[0022] The coupler 170 is assembled within the overlapping portion of the upper waveguide 120 and the lower waveguide 220. The coupler 170 can be embedded and / or positioned between the overlapping portions 190, 290 of the upper waveguide 120 and the lower waveguide 220. The coupler 170 can couple laser light and / or other optical energy from the first portion 190 of the upper waveguide 120 to the second portion 290 of the lower waveguide 220 of the WBG structure 200.
[0020]
[0023] For this purpose, the coupler 170 may include a vertical grating coupler (VGC) on one or more surfaces of the upper waveguide 120. The VGC may include a vertical grating that couples the optical energy of the upper waveguide 120 to the lower waveguide 220 via the overlapping portions 190, 290 of the upper waveguide 120 and the lower waveguide 220. Alternatively, the coupler 170 may include an evanescent tapered coupler (ETC) in one or more tapered portions 190, 290 of the upper waveguide 120 and / or the lower waveguide 220. The ETC can couple the optical energy of the upper waveguide 120 to the lower waveguide 220 without the assistance of a grating. Nevertheless, the coupler 170 (e.g., VGC or ETC) may function as an optical coupler in a cavity between the upper waveguide 120 of the NBG structure 100 and the lower waveguide 220 of the WBG structure 200. Thus, the laser 10 in Figures 1 to 3 can form a composite laser cavity having an upper cavity 110 and a lower cavity 210 formed from semiconductors with different band gaps.
[0021]
[0024] As described above, the upper cavity 110 may be constructed from a semiconductor material having a narrower bandgap than the semiconductor material used to construct the lower cavity 210. In particular, the upper cavity 110 may be constructed from an associated quantum well using a narrow-bandgap semiconductor material, such as InP, GaAs, or alloy layer. For example, the upper cavity 110 may be constructed from a semiconductor material having a bandgap of about 1.34 eV, about 1.42 eV, less than 2 eV, less than 3 eV, or within the range of any two of the above values. In various embodiments, the upper cavity 110, DBR structure 130, DFB structure 160, and coupler 170 may be constructed in a manner similar to a typical semiconductor laser structure, except that they have a very thin lower cladding layer thickness (e.g., less than 1 micron). The very thin lower cladding layer thickness allows for efficient heat transfer to the lower semiconductor structure 200, which may exhibit higher thermal conductivity.
[0022]
[0025] In various embodiments, the WBG structure 200 and its lower cavity 210 may be implemented by a wide bandgap semiconductor material or substrate, such as SiC, AlN, diamond, etc. For example, the WBG structure 200 may be implemented by a semiconductor material having a bandgap within a range of about 3 eV, about 3.3 eV, about 5.47, about 6.2, greater than 3 eV, greater than 5 eV, greater than 6 eV, or between any two of the values described above. The lower waveguide 220 of the WBG structure 200 may guide laser light or other optical energy from the upper waveguide 120 of the NBG structure 100 to the output facet 240 of the lower semiconductor structure 200.
[0023]
[0026] The WBG structure 200 may establish a composite laser cavity through its own coupler or the coupler 170 of the NBG structure 100 having a partial reflection output facet. Further, the WBG structure 200 may provide better heat removal of heat from the NBG structure 100 for higher optical output and efficiency. The lower waveguide 220 of the WBG structure 200 may provide a refractive index lower than that of the upper waveguide 120. The lower refractive index may provide a larger optical mode at the output facet 240 and may enable a lower loss coupling with an external optical fiber compared to the upper waveguide 120. The lower refractive index of the lower waveguide 220 may also enhance the reliability at high optical output at the output facet 240 with less optical damage generated by the reduced density. The lower waveguide 220 of the WBG structure 200 may also provide an optical output coupler that combines different emission wavelengths from a plurality of NBG structures 100 to form a multi-color laser emitter.
[0024]
[0027] It will be understood by those skilled in the art that although this disclosure includes references to specific examples, various changes may be made without departing from the scope of the disclosure and equivalents may be substituted. In addition, modifications may be made to the disclosed examples without departing from the scope of the disclosure. Therefore, this disclosure is not intended to be limited to the disclosed examples but is intended to include all examples included within the scope of the appended claims.
Description of the Reference Signs
[0025] 10 lasers 100 Upper semiconductor structure, NBG structure 101 Top surface of the superstructure 102 Lower surface of the superstructure 103 Side view of the superstructure 110 Top Cavity 120 Upper waveguide 130 DBR structure 140 First Contact 150 Second Contact 160 DFB structure 170 Combiner 180 dielectric 190 Overlapping section, first section, tapered section 200 Lower semiconductor structure, WBG structure 201 Top surface of the substructure 202 Lower surface of the substructure 203 Side view of the substructure 210 Lower Cavity 220 Lower waveguide 230 DBR structure 240 output facets 290 Overlapping section, second section, tapered section
Claims
1. An upper semiconductor substrate comprising an upper surface and a lower surface of an upper semiconductor substrate, A lower semiconductor substrate comprising an upper surface and a lower surface, A composite laser cavity comprising an upper cavity in the upper semiconductor substrate, a lower cavity in the lower semiconductor substrate, and a coupler that couples laser light between the upper cavity and the lower cavity. A laser equipped with, The upper semiconductor substrate has a first band gap, The lower semiconductor substrate has a second band gap that is wider than the first band gap. The lowest surface of the upper semiconductor substrate lies above the uppermost surface of the lower semiconductor substrate, and the upper cavity of the composite laser cavity includes a distributed feedback (DFB) structure.
2. A laser according to claim 1, wherein the upper cavity of the composite laser cavity includes a distributed Bragg reflector (DBR) structure.
3. An upper semiconductor substrate comprising an upper surface and a lower surface of an upper semiconductor substrate, A lower semiconductor substrate comprising an upper surface and a lower surface, A composite laser cavity comprising an upper cavity in the upper semiconductor substrate, a lower cavity in the lower semiconductor substrate, and a coupler that couples laser light between the upper cavity and the lower cavity. A laser equipped with, The upper semiconductor substrate has a first band gap, The lower semiconductor substrate has a second band gap that is wider than the first band gap. The lowest surface of the upper semiconductor substrate lies above the uppermost surface of the lower semiconductor substrate, and the upper cavity of the composite laser cavity includes a distributed Bragg reflector (DBR) structure.
4. A laser according to claim 1 or 3, wherein the lower cavity of the composite laser cavity includes a distributed Bragg reflector (DBR) structure.
5. A laser according to claim 1 or 3, wherein the lower cavity outputs laser light from the output facet of the lower semiconductor substrate.
6. A laser according to claim 1 or 3, The lower semiconductor substrate has a side surface between the upper surface of the lower semiconductor substrate and the lower surface of the lower semiconductor substrate, The lower cavity outputs laser light from an output facet along the side surface of the lower semiconductor substrate. laser.
7. A laser according to claim 1 or 3, wherein the upper cavity partially overlaps with the lower cavity.
8. A laser according to claim 7, wherein the coupler comprises a vertical grating, the vertical grating couples the laser beam between the overlapping portion of the upper cavity and the lower cavity.
9. A laser according to claim 7, wherein the coupler comprises an evanescent tapered coupler, the evanescent tapered coupler couples the laser beam between the overlapping portion of the upper cavity and the lower cavity.
10. A laser according to claim 1 or 3, wherein the lower surface of the upper semiconductor substrate is physically coupled to the upper surface of the lower semiconductor substrate.
11. A laser according to claim 1 or 3, The aforementioned first band gap is less than 2 eV, The aforementioned second band gap is greater than 3 eV. laser.
12. A laser according to claim 1 or 3, The aforementioned first band gap is between 1.34 eV and 2 eV. The aforementioned second band gap is between 3 eV and 6 eV. laser.
13. A laser according to claim 1 or 3, wherein the lower cavity of the composite laser cavity has a lower refractive index than the upper cavity of the composite laser cavity.
14. A laser according to claim 1 or 3, wherein the lower cladding layer of the upper cavity is less than 1 micron thick.
15. A laser according to claim 14, wherein the lower cladding layer is physically coupled to the upper surface of the lower semiconductor substrate.
16. A laser according to claim 1 or 3, wherein the lower semiconductor substrate exhibits a higher thermal conductivity than the upper semiconductor substrate.