Micro-disk laser and preparation method thereof

Abstract

The application discloses a micro-disk laser, comprising a substrate; an optical micro-cavity unit arranged on the substrate and having a disk-shaped micro-cavity; an electrical connection unit for injecting current into the optical micro-cavity unit; a planarization unit covering the substrate, the electrical connection unit and the optical micro-cavity unit, and forming a continuous plane on a side of the electrical connection unit opposite to the optical micro-cavity unit, the electrical connection unit being attached to the continuous plane; and a first electrode arranged on the continuous plane and in contact with the electrical connection unit. By arranging the first electrode on the continuous plane of the planarization unit, the size of the first electrode is not strictly limited, the first electrode with a large area can be arranged, the manufacturing difficulty, cost and internal resistance of the device are reduced, the heat dissipation performance of the device is improved, and the industrialized mass production of the micro-disk laser is suitable. The application discloses a preparation method of the micro-disk laser, which is simple in operation, high in preparation efficiency, and suitable for preparing the micro-disk laser with reduced cost and improved performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor laser, in particular to a micro-disk laser and a preparation method thereof. BACKGROUND

[0002] Microcavity laser is a kind of laser with resonant cavity geometry scale close to wavelength or sub-wavelength in at least one dimension. Due to its low photon loss rate, ultra-small mode volume and low operating threshold, it has a wide range of applications in nonlinear optics, quantum optics and device physics. From the different restriction mechanisms of the cavity to the optical field, optical microcavities can be divided into three forms: Fabry-Perot (F-P) microcavity, photonic crystal microcavity, and whispering gallery mode (WGM) microcavity. Micro-disk laser is a kind of semiconductor laser with whispering gallery mode microcavity. Its optical field mode is established by the total reflection at the edge of the micro-disk due to the refractive index difference between the micro-disk and the air. Micro-disk laser has a small volume, high quality factor, large free spectral width, simple structure and easy integration, and has a wide application prospect in optical communication, optical interconnection and optical information processing.

[0003] At present, the micro-disk laser is generally prepared by growing epitaxial layer material on the substrate, then forming a vertical cylindrical structure by non-selective etching, then selectively etching the lower part of the cylinder inward to obtain a laser structure supported by a support column, and finally preparing a metal electrode above the micro-disk for realizing the electrical injection to the micro-disk laser. In the above micro-disk laser, the edge of the micro-disk extends out of the support column and is exposed to the air. Due to the large refractive index difference between the micro-disk and the air, the light is confined at the edge of the micro-disk to form a disk-shaped microcavity. However, if the metal electrode contacts the edge of the micro-disk, the mode loss will be caused by the coupling of the optical field mode in the micro-disk resonant cavity into the metal electrode, and the yield of the micro-disk laser will be reduced. In order to ensure the product yield of the micro-disk laser, it is usually necessary to strictly limit the area of the metal electrode, and to use expensive electron beam lithography process to prepare the metal electrode above the micro-disk, which increases the difficulty of industrial production of the micro-disk laser and increases the production cost. SUMMARY

[0004] Therefore, the technical problem to be solved by the present application is to overcome the defects of large preparation difficulty and high production cost of the micro-disk laser in the prior art.

[0005] To this end, the present application provides the following technical solutions:

[0006] In a first aspect, the present application provides a micro-disk laser, comprising:

[0007] a substrate;

[0008] an optical microcavity unit disposed on the substrate, the optical microcavity unit having a disc-shaped microcavity;

[0009] an electrical connection unit disposed on a side of the optical microcavity unit distal from the substrate, for injecting an electrical current into the optical microcavity unit;

[0010] a planarization unit, the planarization unit covering the substrate, the electrical connection unit and the optical microcavity unit, and forming a continuous plane on a side of the electrical connection unit distal from the optical microcavity unit, the electrical connection unit being flush with the continuous plane;

[0011] a first electrode disposed on the continuous plane in contact with the electrical connection unit.

[0012] Preferably, in the micro-disc laser as defined above, a projected area of the first electrode on the substrate is greater than a projected area of the electrical connection unit on the substrate.

[0013] Further preferably, in the micro-disc laser as defined above, a projected area of the electrical connection unit on the substrate is greater than a projected area of the optical microcavity unit on the substrate.

[0014] Preferably, in the micro-disc laser as defined above, the optical microcavity unit comprises:

[0015] a first pillar layer;

[0016] a first micro-disc layer disposed between the first pillar layer and the electrical connection unit, an edge of the first micro-disc layer protruding beyond the first pillar layer and extending within the planarization unit, a refractive index of the first micro-disc layer being greater than a refractive index of the planarization unit.

[0017] Further preferably, in the micro-disc laser as defined above, the first micro-disc layer comprises a quantum heterostructure based on a semiconductor material, the quantum heterostructure being selected from at least one of a quantum dot, a quantum wire, a quantum well and a bulk structure.

[0018] Preferably, the semiconductor material is a GaAs-based material or an InP-based material.

[0019] Preferably, in the micro-disc laser as defined above, the electrical connection unit comprises:

[0020] a second pillar layer disposed on a side of the first micro-disc layer distal from the first pillar layer, an edge of the first micro-disc layer protruding beyond the second pillar layer and extending within the planarization unit;

[0021] A second micro-disk layer is disposed between the second pillar layer and the first electrode, an edge of the second micro-disk layer protrudes from the second pillar layer and extends within the planarization unit.

[0022] Further preferably, the micro-disk laser as described above, the first pillar layer and the second pillar layer are formed by the same semiconductor material.

[0023] Preferably, the micro-disk laser as described above, further comprising a second electrode disposed on a side of the substrate opposite to the optical micro-cavity unit.

[0024] In a second aspect, the present application provides a preparation method of a micro-disk laser, comprising the following steps:

[0025] S1, sequentially preparing an optical micro-cavity unit having a disk-shaped micro-cavity and an electrical connection unit for injecting current to the optical micro-cavity unit on a substrate;

[0026] S2, coating a planarization material on an outer side of the substrate, the optical micro-cavity unit and the electrical connection unit, and etching the planarization material to form a continuous planar structure of the planarization material in contact with a surface of the electrical connection unit opposite to the optical micro-cavity unit, to obtain a planarization unit;

[0027] S3, preparing a first electrode in contact with the electrical connection unit on the continuous planar structure to obtain a micro-disk laser.

[0028] Preferably, the preparation method as described above, the step S3 further comprises:

[0029] Preferably, the preparation method as described above, the step S1 comprises:

[0030] Preferably, the preparation method as described above, the step S1 comprises:

[0031] S11, sequentially epitaxially growing a lower confinement layer, an active layer, an upper confinement layer and an electrode contact layer on a substrate to form a semiconductor epitaxial wafer on the substrate;

[0032] S12, depositing a protection layer on the semiconductor epitaxial wafer;

[0033] S13, performing a patterning process on the protection layer to obtain a patterned protection layer; the patterned protection layer corresponds to a first region of the semiconductor epitaxial wafer, and a second region of the semiconductor epitaxial wafer is located at a periphery of the first region;

[0034] S14, performing an etching process to remove the semiconductor epitaxial wafer located in the second region;

[0035] S15, performing a selective etching process to remove the patterned protection layer, the lower confinement layer and the upper confinement layer are etched inwardly along a direction perpendicular to the epitaxial growth direction, corresponding to obtain a first pillar layer and a second pillar layer; the edge of the active layer extends out of the first pillar layer and the second pillar layer to form a suspended structure, to obtain a first micro-disk layer; the edge of the electrode contact layer extends out of the second pillar layer to form a suspended structure, to obtain a second micro-disk layer.

[0036] Further preferably, the preparation method described above, the step S14 comprises:

[0037] Performing a wet etching process, immersing the semiconductor epitaxial wafer in a wet etching solution along the epitaxial growth direction, removing the semiconductor epitaxial wafer located in the second region, and the immersion depth of the electrode contact layer to the lower confinement layer in the wet etching solution decreases in turn.

[0038] Further preferably, the preparation method described above, the step S14 further comprises:

[0039] Performing an etching process to partially etch the substrate located in the second region to form a protrusion on the substrate in contact with the lower confinement layer.

[0040] Preferably, the preparation method described above, the step S2 comprises:

[0041] Etching the planarization material to expose the electrical connection unit; continuing to etch the exposed area of the electrical connection unit, so that the side surface of the electrical connection unit facing away from the optical microcavity unit is attached to the planarization material to form a continuous planar structure.

[0042] The technical scheme of the present application has the following advantages:

[0043] 1. The micro-disk laser provided by the present application comprises a substrate, an optical microcavity unit, an electrical connection unit, a planarization unit and a first electrode, the electrical connection unit separates the optical microcavity unit and the first electrode, the first electrode does not directly contact the optical microcavity unit with a disk-shaped microcavity, which can avoid energy loss caused by mode coupling into the electrode due to the edge of the electrode contacting the optical microcavity. The planarization unit is provided, and the electrical connection unit is attached to a continuous plane, so that the first electrode located on the continuous plane can be connected to the electrical connection unit. The other side of the electrical connection unit contacts the optical microcavity unit, which can serve as a connection channel between the optical microcavity unit and the first electrode, realizing the electrical connection between the optical microcavity unit and the first electrode, injecting current into the optical microcavity unit, so that the optical microcavity unit is excited by electricity to radiate photons, and the light propagates along the edge of the disk-shaped microcavity and is totally reflected, so that the light field mode is selectively strengthened to emit laser.

[0044] Since the optical microcavity unit is relatively separated from the first electrode, the size of the first electrode is not limited by the disc-shaped microcavity, and the first electrode with a large area can be prepared under the support of the planarization unit. Since the size of the first electrode does not need to be strictly limited, the expensive electron beam lithography process is not needed in the preparation of the first electrode, the preparation difficulty and the manufacturing cost of the micro-disc laser are reduced, and the large-scale industrial production of the micro-disc laser is facilitated.

[0045] 2. The micro-disc laser provided by the present application, the projection area of the electrical connection unit on the substrate is greater than the projection area of the electrical connection unit on the substrate. The area of the first electrode is increased, so that the heat in the micro-disc laser is dissipated through the first electrode with a larger area, which is beneficial to improve the heat dissipation effect of the micro-disc laser. At the same time, the contact resistance between the first electrode and the electrical connection unit is reduced, so that the device performance and reliability are improved, and a micro-disc laser with low resistance and low thermal resistance is obtained.

[0046] Further, the projection area of the electrical connection unit on the substrate is greater than the projection area of the optical microcavity unit on the substrate. While increasing the area of the electrical connection unit and improving the contact area between the electrical connection unit and the first electrode, the area of the optical microcavity unit is further reduced to reduce the volume of the disc-shaped microcavity, which is beneficial to increase the distance between the optical field modes in the disc-shaped microcavity to realize single-mode output and reduce the threshold current, and a micro-disc laser with low threshold, low energy consumption and high quality factor is obtained.

[0047] 3. The micro-disc laser provided by the present application, the optical microcavity unit comprises: a first pillar layer; a first micro-disc layer arranged between the first pillar layer and the electrical connection unit, the edge of the first micro-disc layer protrudes from the first pillar layer and extends in the planarization unit, and the refractive index of the first micro-disc layer is greater than the refractive index of the planarization unit.

[0048] The edge of the first micro-disc layer protrudes from the first pillar layer and extends in the planarization unit, and the first micro-disc layer with high refractive index is covered by the planarization unit with low refractive index, so that the light is totally reflected at the edge of the first micro-disc layer, and a disc-shaped microcavity with "echo wall mode" is formed in the first micro-disc layer. The first pillar layer supports the first micro-disc layer on the substrate, and since the edge of the first micro-disc layer protrudes from the first pillar layer, the first pillar layer forms a strong restriction on the optical field in the first micro-disc layer in the vertical direction, thereby reducing the optical loss in the disc-shaped microcavity. On the other hand, the first pillar layer can act as a current channel to introduce current into the first micro-disc layer.

[0049] 4. The micro-disc laser provided by the present application, the electrical connection unit comprises: a second pillar layer arranged on the side of the first micro-disc layer away from the first pillar layer, the edge of the first micro-disc layer protrudes from the second pillar layer and extends in the planarization unit; a second micro-disc layer arranged between the second pillar layer and the first electrode, the edge of the second micro-disc layer protrudes from the second pillar layer and extends in the planarization unit.

[0050] The electrical connection unit supports the second micro-disk layer on the first micro-disk layer by the second pillar layer, the edge of the first micro-disk layer protrudes from the second pillar layer to ensure that the first micro-disk layer is covered by the planarization unit with a relatively low refractive index, a strong restriction on the optical field is formed at the edge of the first micro-disk layer, and the formation of the disk-shaped micro-cavity in the first micro-disk layer is ensured. The second pillar layer supports the second micro-disk layer at the same time, the edge of the second micro-disk layer protrudes from the second pillar layer and has a relatively large area, the second micro-disk layer is in direct contact with the first electrode, and the current is injected into the first micro-disk layer through the second micro-disk layer and the second pillar layer. The second micro-disk layer is in contact with the first electrode with a relatively large area, which is conducive to reducing the resistance of the micro-disk laser and improving heat dissipation.

[0051] 5. The micro-disk laser provided by the application is prepared by coating a planarization material on the outside of the substrate, the optical micro-cavity unit and the electrical connection unit, the planarization material is formed into a continuous planar structure that is attached to the surface of the electrical connection unit that is opposite to the optical micro-cavity unit, and a planarization unit is obtained. The first electrode is prepared on the planarization unit, and the size of the first electrode does not need to be strictly limited, which avoids the use of expensive electron beam lithography technology, reduces the preparation difficulty and manufacturing cost of the micro-disk laser, improves the preparation efficiency of the device, and is conducive to industrialized mass production. The first electrode and the optical micro-cavity unit are separated by the electrical connection unit and the planarization unit, which avoids the contact between the first electrode and the edge of the optical micro-cavity unit, and prevents the square mode from being coupled into the first electrode to cause optical loss.

[0052] 6. The micro-disk laser provided by the application is prepared by performing a wet etching process to remove the lower confinement layer, the active layer, the upper confinement layer and the electrode contact layer in the second region. By using the isotropy of the wet etching process, the width of the lateral etching is close to the depth of the vertical etching. Therefore, the greater the immersion depth in the wet etching liquid, the greater the width of the lateral etching, and the smaller the width of the remaining part after the wet etching. That is, after the wet etching, the width of the remaining part of the electrode contact layer, the upper confinement layer, the active layer and the lower confinement layer decreases in turn, and presents an inverted trapezoidal shape with the long side on the top and the short side on the bottom in the vertical cross section. By performing a selective etching process on the above-mentioned device structure after the wet etching, the second micro-disk layer, the second pillar layer, the first micro-disk layer and the second pillar layer with the projection area on the substrate decreasing in turn can be obtained, and the projection area of the electrical connection unit on the substrate is greater than the projection area of the optical micro-cavity unit on the substrate. Since the high-precision lithography technology is not required in the preparation process, the preparation difficulty and manufacturing cost of the micro-disk laser are effectively reduced, and the preparation efficiency of the micro-disk laser is improved. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort based on these drawings.

[0054] Figure 1 Structure diagram of the semiconductor laser provided in the first embodiment of the present application;

[0055] Figure 2 Structure diagram of the semiconductor laser provided in the second embodiment of the present application;

[0056] Figure 3 Process diagram of the semiconductor laser provided in the first embodiment of the present application; Figure 4 Process diagram of the semiconductor laser provided in the first embodiment of the present application; Figure 5 Process diagram of the semiconductor laser provided in the first embodiment of the present application; Figure 6 Process diagram of the semiconductor laser provided in the first embodiment of the present application; Figure 7 Process diagram of the semiconductor laser provided in the first embodiment of the present application; Figure 8 Process diagram of the semiconductor laser provided in the first embodiment of the present application; Figure 9 Process diagram of the semiconductor laser provided in the first embodiment of the present application; Figure 10 Process diagram of the semiconductor laser provided in the first embodiment of the present application;

[0057] Figure 11 Process diagram of the semiconductor laser provided in the second embodiment of the present application; Figure 12 Process diagram of the semiconductor laser provided in the second embodiment of the present application;

[0058] Explanation of reference numerals:

[0059] 1 - first electrode;

[0060] 2 - electrical connection unit, 21 - second micro-disk layer, 22 - second pillar layer;

[0061] 3 - optical microcavity unit, 31 - first micro-disk layer, 32 - first pillar layer;

[0062] 4 - planarization unit;

[0063] 5 - substrate;

[0064] 6 - second electrode

[0065] 21' - electrode contact layer, 22' - upper confinement layer, 31' - active layer, 32' - lower confinement layer, 7' - protective layer, 8' - photoresist. DETAILED DESCRIPTION

[0066] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0067] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0068] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0069] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0070] Example 1

[0071] The present embodiment provides a micro-disc laser, such as Figure 1As shown, it comprises a substrate 5, an optical microcavity unit 3, an electrical connection unit 2, a planarization unit 4, a first electrode 1 and a second electrode 6. The optical microcavity unit 3 is arranged on the substrate 5 and has a disc-shaped microcavity. The electrical connection unit 2 is arranged on the side of the optical microcavity unit 3 opposite to the substrate 5. The planarization unit 4 covers the substrate 5, the optical microcavity unit 3 and the electrical connection unit 2, and forms a continuous plane on the side of the electrical connection unit 2 opposite to the optical microcavity unit 3. The first electrode 1 is arranged on the continuous plane of the planarization unit 4 and is in contact with the electrical connection unit 2. When the micro-disk laser is in operation, an external electric field is applied to the micro-disk laser through the first electrode 1 and the second electrode 6 to apply a forward bias voltage to the micro-disk laser. The forward current is conducted in the micro-disk laser to cause the particle number inversion in the optical microcavity unit 3. The photons are radiated by the recombination of the electrons and the holes. The light is transmitted and oscillated by multiple reflections on the total reflection interface of the disc-shaped microcavity to cause the resonance. The light field of a specific mode is selectively strengthened to realize the laser emission. The disc-shaped microcavity has a simple structure and a strong light restriction effect, which can improve the quality factor of the micro-disk laser and realize the miniaturization and high integration of the micro-disk laser.

[0072] It should be noted that, when the electrode is prepared on the micro-disk, the size of the electrode needs to be strictly limited to avoid the loss of the light field coupling into the first electrode 1 caused by the contact between the edge of the micro-disk and the electrode. The electrode is prepared within the range of the micro-disk. In order to ensure the formation of the microcavity, a small volume micro-disk is usually prepared, so that the disc-shaped microcavity of the micro-disk is in the order of the wavelength of the light in the semiconductor medium to generate quantum effect. The small volume of the micro-disk further increases the preparation difficulty and the manufacturing cost of the electrode prepared on the micro-disk.

[0073] To solve the above problems, the micro-disk laser provided by the embodiment is arranged with the electrical connection unit 2 between the optical microcavity unit 3 and the first electrode 1, so that the first electrode 1 is separated from the optical microcavity unit 3. The contact between the first electrode 1 and the edge of the disc-shaped microcavity is avoided to cause the light field coupling into the first electrode 1 in the disc-shaped microcavity. The electrical connection unit 2 is used as the connection channel between the first electrode 1 and the optical microcavity unit 3, so that the current is injected into the optical microcavity unit 3 through the electrical connection unit 2 to realize the electrical connection between the first electrode 1 and the optical microcavity unit 3. The continuous plane of the planarization unit 4 supports the first electrode 1. The ohmic contact between the electrical connection unit 2 and the first electrode 1 is realized, and the first electrode 1 with a large area is supported. The contact resistance in the micro-disk laser is reduced, and the heat is dissipated through the first electrode 1 with a large area to reduce the thermal resistance in the micro-disk laser. On the other hand, the size of the first electrode 1 does not need to be strictly limited, which reduces the preparation difficulty and the manufacturing cost of the electrode and is beneficial to the industrial mass production of the micro-disk laser.

[0074] Specifically, the optical microcavity unit 3 comprises a first pillar layer 32 on the substrate 5, and a first micro-disk layer 31 between the first pillar layer 32 and the electrical connection unit 2. The electrical connection unit 2 comprises a second pillar layer 22 on the side of the first micro-disk layer 31 opposite to the first pillar layer 32, and a second micro-disk layer 21 between the second pillar layer 22 and the first electrode 1. The substrate 5, the first pillar layer 32, the first micro-disk layer 31, the second pillar layer 22 and the second micro-disk layer 21 are covered by the planarization unit 4, which forms a continuous plane on the side of the second micro-disk layer 21 opposite to the optical microcavity unit 3, and the second micro-disk layer 21 is attached to the continuous plane. The first electrode 1 is on the continuous plane and in contact with the first micro-disk layer 31, and the second electrode 6 is on the side of the substrate 5 opposite to the first pillar layer 32. The edge of the first micro-disk layer 31 protrudes from the first pillar layer 32 and the second pillar layer 22 and extends in the planarization unit 4, for example, the first micro-disk layer 31 is a disc, and the first pillar layer 32 and the second pillar layer 22 are cylinders with a bottom diameter smaller than that of the first micro-disk layer 31, and the first micro-disk layer 31 is between the two cylinders so that its edge protrudes from the first pillar layer 32 and the second pillar layer 22. By selecting the materials forming the first micro-disk layer 31 and the planarization unit 4, the refractive index of the first micro-disk layer 31 is greater than that of the planarization unit 4. The first micro-disk layer 31 with high refractive index is covered by the planarization unit 4 with low refractive index, and the light in the first micro-disk layer 31 is totally reflected at the contact interface between the two, forming a disk-shaped microcavity based on the "echo corridor" mode in the first micro-disk layer 31. Since the edge of the first micro-disk layer 31 protrudes from the first pillar layer 32 and the second pillar layer 22, a strong restriction on the light field in the first micro-disk layer 31 is formed in the vertical direction, avoiding scattering loss of the light in the first micro-disk layer 31. The first pillar layer 32 and the second pillar layer 22 on both sides of the first micro-disk layer 31 can serve as a communication channel between the first micro-disk layer 31 and the first electrode 1 and the second electrode 6 while supporting the first micro-disk layer 31 and the second micro-disk layer 21, and can inject current into the first micro-disk layer 31 to excite laser in the disk-shaped microcavity of the first micro-disk layer 31. The edge of the second micro-disk layer 21 protrudes from the second pillar layer 22 and extends in the planarization unit 4, for example, the second pillar layer 22 is a cylinder, and the second micro-disk layer 21 is a disc with a diameter greater than the bottom diameter of the second pillar layer 22, and the second micro-disk layer 21 is supported by the second pillar layer 22 so that its edge protrudes from the second pillar layer 22 to achieve ohmic contact with the second electrode 6 in a larger area, which is conducive to reducing the resistance of the micro-disk laser and improving the heat dissipation effect in the device.

[0075] As a preferred embodiment, as Figure 1As shown, the projected area of the first electrode 1 on the substrate 5 is larger than the projected area of the electric connection unit 2 on the substrate 5, that is, the projected area of the first electrode 1 on the substrate 5 is larger than the projected area of the second micro-disk layer 21 on the substrate 5, and the first electrode 1 completely covers the second micro-disk layer 21. By increasing the area of the first electrode 1, heat is dissipated through the first electrode 1 with a larger area, improving the heat dissipation performance of the device. At the same time, the first electrode 1 and the second micro-disk layer 21 have the maximum contact area, reducing the internal resistance of the device. In addition, the increase of the area of the first electrode 1 reduces the precision requirement for its manufacturing, reducing the difficulty of device manufacturing.

[0076] As an optional embodiment, the first electrode 1 is connected to the positive pole of an external power supply as a P-type electrode, and the second electrode 6 is connected to the negative pole of the external power supply as an N-type metal electrode. The first electrode 1 and the second electrode 6 can be a single-layer structure formed of a metal material with good electrical conductivity, such as Cr, Au, Ni, Ti, or the like, or a laminated structure formed of different metal materials, such as Cr / Au, Ni / Au, Ti / Au, or the like. The second micro-disk layer 21, the second pillar layer 22, the first micro-disk layer 31, the first pillar layer 32, and the substrate 5 are selected from a group of III-V semiconductor materials, such as InP-based materials, GaAs-based materials, or the like. Among them, the second micro-disk layer 21 and the second pillar layer 22 located between the first electrode 1 and the first micro-disk layer 31 are formed of a P-type semiconductor material, and the first pillar layer 32 and the substrate 5 located between the second electrode 6 and the first micro-disk layer 31 are formed of an N-type semiconductor material. The first micro-disk layer 31 contains a quantum heterostructure based on a semiconductor material, and the quantum heterostructure can be selected from at least one of a quantum dot, a quantum wire, a quantum well, and a bulk structure. For example, the substrate 5 is selected to be formed of an N-type GaAs material, the first pillar layer 32 is selected to be formed of an N-type AlGaAs material, the first micro-disk layer 31 has a single quantum well structure or a multiple quantum well structure formed by alternately stacking GaAs and InGaAs, the second pillar layer 22 is selected to be formed of a P-type AlGaAs material, and the second micro-disk layer 21 is selected to be formed of a P-type GaAs material. The first pillar layer 32 and the second pillar layer 22 respectively serve as N-type and P-type confinement layers located on both sides of the first micro-disk layer 31, confine carriers in the disk-shaped microcavity of the first micro-disk layer 31, and improve the device gain of the micro-disk laser. The first pillar layer 32 and the second pillar layer 22 are selected to be formed of the same semiconductor material, so that the first pillar layer 32 and the second pillar layer 22 can be obtained synchronously through a selective etching process in the preparation process of the semiconductor device, the automatic alignment of the first micro-disk layer 31 and the second micro-disk layer 21 is realized, and the process difficulty of the preparation of the micro-disk laser is reduced. The planarization unit 4 is formed by coating a planarization material on the outside of the substrate 5, the first micro-disk layer 31, the first pillar layer 32, the second micro-disk layer 21, and the second pillar layer 22. The planarization material is specifically benzocyclobutene. Firstly, since the refractive index of benzocyclobutene is less than that of the semiconductor material of the first micro-disk layer 31, a total reflection section can be formed at the edge where the first micro-disk layer 31 contacts the planarization unit 4, so as to ensure the disk-shaped microcavity in the first micro-disk layer 31. In addition, benzocyclobutene is an electrically insulating material with high planarization rate and film-forming performance, which is conducive to improving the device strength and sealing performance of the micro-disk laser, and optimizing the device performance.

[0077] As an alternative embodiment, the first electrode 1 can also be connected to the negative terminal of the power supply as an N-type electrode, and the second electrode 6 is connected to the positive terminal of the power supply as a P-type electrode. In this case, the second micro-disk layer 21 and the second pillar layer 22 between the first electrode 1 and the first micro-disk layer 31 are formed of N-type semiconductor material, and the substrate 5 and the first pillar layer 32 between the second electrode 6 and the first micro-disk layer 31 are formed of P-type semiconductor material. As a further alternative, the substrate 5 can also be formed of insulating material, for example, an undoped GaAs substrate. In this case, if the first electrode 1 is a P-type electrode and the second electrode 6 is an N-type electrode, an N-type electrode contact layer is epitaxially grown on the side of the substrate 5 facing the first pillar layer 32. The second electrode 6 can be disposed on the continuous plane of the planarization unit 4 on the same side as the first electrode 1, a through hole is formed in the planarization unit 4 for the second electrode 6 to extend, and the second electrode 6 realizes ohmic contact with the N-type electrode contact layer on the substrate 5 through the through hole. As a variation, if the first electrode 1 is an N-type electrode and the second electrode 6 is a P-type electrode, a P-type electrode contact layer is epitaxially grown on the side of the substrate 5 facing the first pillar layer 32, and the second electrode 6 realizes ohmic contact with the P-type electrode contact layer on the substrate 5 through the through hole.

[0078] As another alternative embodiment, the first micro-disk layer 31 and the second micro-disk layer 21 can each be selected to have other shapes, for example, polygonal, elliptical, etc., as long as the disk-shaped micro-cavity can be formed in the second micro-disk layer 21. As a further alternative, the first pillar layer 32 and the second pillar layer 22 can each be selected to have other shapes, for example, triangular column, quadrangular column, etc., as long as the edges of the first micro-disk layer 31 protrude out of the first pillar layer 32 and the second pillar layer 22 and extend in the planarization unit 4, and the edges of the second micro-disk layer 21 protrude out of the second pillar layer 22 and extend in the planarization unit 4.

[0079] Embodiment 2

[0080] This embodiment provides a micro-disk laser, as shown in Figure 2 The difference between the micro-disk laser of this embodiment and that of Embodiment 1 is that:

[0081] The projected area of the electrical connection unit 2 on the substrate 5 is greater than the projected area of the optical micro-cavity unit 3 on the substrate 5, that is, the projected area of the second micro-disk layer 21 on the substrate 5 is greater than the projected area of the first micro-disk layer 31 on the substrate 5, and the diameter of the second micro-disk layer 21 is smaller than the diameter of the first micro-disk layer 31. While the projected area of the first electrode 1 is greater than the projected area of the second micro-disk layer 21 to increase the contact area between the first electrode 1 and the second micro-disk layer 21, the area of the first micro-disk layer 31 is further reduced to reduce the volume of the first micro-disk layer 31, increase the spacing of the optical field modes in the disk-shaped micro-cavity, and realize single-mode emission of laser. In Figure 2In the micro-disk laser shown, the first electrode 1, the second micro-disk layer 21 and the first micro-disk layer 31 are disks with diameters decreasing in turn, the first pillar layer 32 and the second pillar layer 22 are truncated cones with fan-shaped outer circumferential surfaces, and the first pillar layer 32 and the second pillar layer 22 respectively contact the first micro-disk layer 31 and the second micro-disk layer 21 with the transverse sections having the largest diameters, thereby forming good support for the first micro-disk layer 31 and the second micro-disk layer 21 while ensuring the formation of the disk-shaped micro-cavity in the first micro-disk layer 31.

[0082] Embodiment 3

[0083] This embodiment provides a preparation method of the micro-disk laser in Embodiment 1, as shown in Figure 3 Figure 10 Specifically, the method comprises the following steps:

[0084] S1, sequentially preparing, on the substrate 5, the optical microcavity unit 3 having the disk-shaped micro-cavity, and the electrical connection unit 2 for injecting current into the optical microcavity unit 3.

[0085] S11, as shown in Figure 3 sequentially epitaxially growing, on the substrate 5, the lower confinement layer 32', the active layer 31', the upper confinement layer 22' and the electrode contact layer 21', to form a semiconductor epitaxial wafer on the substrate 5. Specifically, the substrate 5 is formed of N-type GaAs material, the lower confinement layer 32' is epitaxially grown of N-type AlGaAs material on the substrate 5, the active layer 31' is epitaxially grown of single quantum well structure or multiple quantum well structure formed by alternately stacking InGaAs material and GaAs material on the lower confinement layer 32', the upper confinement layer 22' is epitaxially grown of P-type AlGaAs material on the active layer 31', and the electrode contact layer 21' is epitaxially grown of P-type GaAs material on the upper confinement layer 22'. The epitaxial growth method can be selected from PECVD, MOCVD, MBE and LPCVD.

[0086] S12, as shown in Figure 4 depositing dielectric material on the electrode contact layer 21' to form a protective layer 7'. The dielectric material can be selected from SiO2, and the deposition method can be selected from plasma-enhanced chemical vapor deposition.

[0087] S13, as shown in Figure 5 and Figure 6 ​As shown, the protective layer 7' is patterned, specifically: a photoresist 8' is coated on the protective layer 7', exposure treatment is performed using a mask plate, so that the photoresist 8' forms a photoresist 8' removal area and a photoresist 8' retention area, the photoresist 8' removal area is removed after development, and after etching away the protective layer 7' corresponding to the photoresist 8' removal area, the photoresist 8' covering the protective layer 7' is peeled off, to obtain a patterned protective layer 7'. The region of the patterned protective layer 7' corresponding to the epitaxial growth direction is named the first region, and the periphery of the first region is defined as the second region.

[0088] S14, as shown, Figure 7 the dry etching process is performed, so that the lower limiting layer 32', the active layer 31', the upper limiting layer 22' and the electrode contact layer 21' located in the second region are removed, and the substrate 5 located in the second region is partially removed, to form a protrusion on the substrate 5 towards and in contact with the lower limiting layer 32'. Specifically, by performing the dry etching process, the lower limiting layer 32', the active layer 31', the upper limiting layer 22' and the electrode contact layer 21' have the same lateral etching depth, to obtain a cylindrical semiconductor epitaxial wafer with a vertical sidewall to the substrate 5. By forming a protrusion on the substrate 5 in contact with the lower limiting layer 32', it can be ensured that the semiconductor epitaxial wafer located in the first region is etched sufficiently.

[0089] S15, as shown, Figure 8 the selective etching process is performed, so that the protective layer 7', the lower limiting layer 32' and the upper limiting layer 22' are etched inward in a direction perpendicular to the epitaxial growth direction, to completely remove the protective layer 7' and partially remove the lower limiting layer 32' and the upper limiting layer 22', to obtain a cylindrical first pillar layer 32 and a second pillar layer 22. The edge of the active layer 31' which has not been etched protrudes from the first pillar layer 32 and the second pillar layer 22 to form a suspended structure, to obtain a disc-shaped first micro-disk layer 31; the edge of the electrode contact layer 21' which has not been etched protrudes from the second pillar layer 22 to form a suspended structure, to obtain a disc-shaped second micro-disk layer 21. For example, the device obtained in step S14 is immersed in a hydrofluoric acid solution, so that the SiO2 material and the AlGaAs material are selectively etched, wherein the SiO2 material has a relatively high dissolution rate in the hydrofluoric acid solution, and the AlGaAs material has a relatively low dissolution rate. After a certain processing time, the protective layer 7' formed of the SiO2 material is completely etched, and the lower limiting layer 32' and the upper limiting layer 22' formed of the AlGaAs material are partially etched to form cylindrical structures with the same diameter, and the active layer 31' and the electrode contact layer 21' form disc-shaped structures with the same diameter. The first pillar layer 32 and the first micro-disk layer 31 form an optical microcavity unit 3, and the second pillar layer 22 and the second micro-disk layer 21 form an electrical connection unit 2.

[0090] S2, coating a planarization material outside the substrate 5, the optical microcavity unit 3 and the electrical connection unit 2, etching the planarization material to form a continuous planar structure adhering to the side surface of the electrical connection unit 2 opposite to the optical microcavity unit 3, and obtaining the planarization unit 4.

[0091] Specifically, as shown in Figure 9 and Figure 10 , coating a benzocyclobutene material outside the substrate 5, the first pillar layer 32, the first micro-disk layer 31, the second micro-disk layer 21 and the second pillar layer 22, etching the benzocyclobutene material to form a top surface until the second micro-disk layer 21 is exposed, and continuing to etch the exposed area of the second micro-disk layer 21 until the top surface of the benzocyclobutene material adheres to the side surface of the second micro-disk layer 21 opposite to the second pillar layer 22, forming a continuous planar structure, and obtaining the planarization unit 4.

[0092] S3, preparing the first electrode 1 in contact with the second micro-disk layer 21 on the continuous planar surface of the planarization unit 4, and preparing the second electrode 6 on the side of the substrate 5 opposite to the optical microcavity unit 3, and the preparation method of the first electrode 1 and the second electrode 6 can be selected from evaporation, sputtering and the like, and obtaining the micro-disk laser in Figure 1 after annealing. As a preferred, the projection area of the first electrode 1 on the substrate 5 is larger than the projection area of the electrical connection unit 2 on the substrate 5, that is, the projection area of the second micro-disk layer 21 on the substrate 5, so as to increase the contact area between the second micro-disk layer 21 and the first electrode 1, reduce the resistance value in the micro-disk laser and improve the heat dissipation performance.

[0093] The above preparation method can simultaneously form the first pillar layer 32, the first micro-disk layer 31, the second pillar layer 22 and the second micro-disk layer 21 through a selective etching process, realizes the automatic alignment of the first micro-disk layer 31 and the second micro-disk layer 21, reduces the preparation difficulty of the micro-disk laser and improves the preparation efficiency. The second micro-disk layer 21 and the second pillar layer 22 are arranged between the first micro-disk layer 31 and the first electrode 1, avoiding the contact between the first electrode 1 and the edge of the disk-shaped microcavity to cause the coupling of the light field mode into the first electrode 1 and generate optical loss. At the same time, the first electrode 1 is prepared on the continuous planar surface of the planarization unit 4, without the need to strictly limit the size of the first electrode 1, avoiding the use of expensive electron beam lithography process, reducing the preparation difficulty and manufacturing cost of the first electrode 1, and improving the preparation efficiency.

[0094] Embodiment 4

[0095] The embodiment provides a preparation method of the micro-disk laser in Embodiment 2, which is different from the preparation method provided in Embodiment 3 in that:

[0096] S14, as shown inFigure 11 As shown, an etching process is performed to remove the lower confinement layer 32', active layer 31', upper confinement layer 22', and electrode contact layer 21' located in the second region. The substrate 5 located in the second region is partially removed, and a protrusion is formed on the substrate 5 facing and contacting the lower confinement layer 32'. Specifically, a wet etching process is performed, in which the semiconductor epitaxial wafer located on the substrate 5 is vertically immersed in the etching solution, such that the immersion depth of the lower confinement layer 32', active layer 31', upper confinement layer 22', and electrode contact layer 21' in the etching solution decreases sequentially. Since wet etching is isotropic, the width of the lateral etching is close to the depth of the vertical etching. That is, the greater the immersion depth, the greater the width of the lateral etching, and the less part is retained after etching. After etching, a semiconductor epitaxial wafer with the width increasing sequentially from the lower confinement layer 32' to the electrode contact layer 21' is obtained. The vertical cross-section of the semiconductor epitaxial wafer is an inverted trapezoid with the long side on top and the short side on the bottom.

[0097] S15, such as Figure 12 As shown, a selective etching process is performed to etch the protective layer 7', lower confinement layer 32', and upper confinement layer 22' inward in a direction perpendicular to the epitaxial growth direction, completely removing the protective layer 7' and partially removing the lower confinement layer 32' and upper confinement layer 22', resulting in a first pillar layer 32 and a second pillar layer 22 with fan-shaped frustum outer surfaces. The edge of the unetched active layer 31' protrudes beyond the first pillar layer 32 and the second pillar layer 22, forming a suspended structure, resulting in a disk-shaped first microdisk layer 31; the edge of the unetched electrode contact layer 21' protrudes beyond the second pillar layer 22, forming a suspended structure, resulting in a disk-shaped second microdisk layer 21. Because the width of the upper confinement layer 22' is greater than the width of the lower confinement layer 32' after wet etching, and the width of the power contact layer is greater than the width of the active layer 31', after selective etching, the maximum radius of the transverse cross-section of the first pillar layer 32 is less than the maximum radius of the transverse cross-section of the second pillar layer 22, and the radius of the first microdisk layer 31 is less than the radius of the second microdisk layer 21. The first pillar layer 32 and the first microdisc layer 31 form an optical microcavity unit 3, and the second pillar layer 22 and the second microdisc layer 21 form an electrical connection unit 2. The projected area of ​​the electrical connection unit 2 on the substrate 5 is greater than the projected area of ​​the optical microcavity unit 3 on the substrate 5.

[0098] The preparation method can obtain the electrode contact layer 21', the upper limit layer 22', the active layer 31' and the lower limit layer 32' with widths decreasing in turn by performing the wet etching process; the first micro-disk layer 31 and the second micro-disk layer 21 are automatically aligned by the wet etching process combined with the selective etching process, and the radius of the second micro-disk layer 21 is greater than the radius of the first micro-disk layer 31, so that the contact area between the second micro-disk layer 21 and the first electrode 1 is increased, the device heat dissipation performance is improved, the device resistance is reduced, the volume of the disk-shaped micro-cavity of the first micro-disk layer 31 is further reduced, the single-mode output of the device is realized, the micro-disk laser with high performance is obtained. Meanwhile, the preparation method does not need to use the photolithography technology with high precision when the first micro-disk layer 31 and the second micro-disk layer 21 with different radii are prepared, the preparation difficulty and the manufacturing cost of the micro-disk laser are effectively reduced, and the preparation efficiency of the micro-disk laser is improved.

[0099] Obviously, the above embodiments are only examples for clearly illustrating the present application, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. All the embodiments do not need to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A micro-disk laser, characterized by, The application relates to a semiconductor laser device, comprising: a substrate; an optical microcavity unit arranged on the substrate, the optical microcavity unit having a dished microcavity; the optical microcavity unit is adapted to radiate photons under electrical excitation, the photons being totally reflected at the edge of the dished microcavity so that a light field mode is selectively enhanced to emit laser light; an electrical connection unit arranged on a side of the optical microcavity unit away from the substrate for injecting an electrical current into the optical microcavity unit; a planarization unit covering the substrate, the electrical connection unit and the optical microcavity unit, and forming a continuous plane on a side of the electrical connection unit facing away from the optical microcavity unit, the electrical connection unit being attached to the continuous plane; a first electrode arranged on the continuous plane and in contact with the electrical connection unit; the optical microcavity unit comprises a first pillar layer and a first micro-dish layer, the first micro-dish layer being arranged between the first pillar layer and the electrical connection unit, the edge of the first micro-dish layer protruding from the first pillar layer and extending within the planarization unit, the refractive index of the first micro-dish layer being greater than the refractive index of the planarization unit; the electrical connection unit comprises a second pillar layer and a second micro-dish layer, the second pillar layer being arranged on a side of the first micro-dish layer facing away from the first pillar layer, the edge of the first micro-dish layer protruding from the second pillar layer and extending within the planarization unit, the second micro-dish layer being arranged between the second pillar layer and the first electrode, the edge of the second micro-dish layer protruding from the second pillar layer and extending within the planarization unit.

2. The micro-disk laser of claim 1, wherein, The projected area of the first electrode on the substrate is greater than the projected area of the electrical connection unit on the substrate.

3. The micro-disk laser of claim 2, wherein, The projected area of the electrical connection unit on the substrate is greater than the projected area of the optical microcavity unit on the substrate.

4. The micro-disk laser of claim 1, wherein, The first micro-dish layer comprises a quantum heterostructure based on a semiconductor material, the quantum heterostructure being selected from at least one of a quantum dot, a quantum wire, a quantum hydrazine and a bulk structure; the semiconductor material is a GaAs-based material or an InP-based material.

5. The micro-disk laser of claim 1, wherein, The first pillar layer and the second pillar layer are formed of the same semiconductor material.

6. The micro-disk laser of any of claims 1-5, wherein, A second electrode is arranged on a side of the substrate facing away from the optical microcavity unit.

7. A method of fabricating a micro-disk laser, comprising: The application further relates to a method for manufacturing a semiconductor laser device, comprising the following steps: ​ S1, sequentially preparing an optical microcavity unit having a dished microcavity and an electrical connection unit for injecting an electrical current into the optical microcavity unit on a substrate; the optical microcavity unit is adapted to radiate photons under electrical excitation, the photons being totally reflected at the edge of the dished microcavity so that a light field mode is selectively enhanced to emit laser light; comprising: S11, sequentially epitaxially growing a lower confinement layer, an active layer, an upper confinement layer and an electrode contact layer on the substrate to form a semiconductor epitaxial wafer on the substrate; S12, epitaxially growing a protective layer on the semiconductor epitaxial wafer; S13, performing a patterning process on the protective layer to obtain a patterned protective layer; the patterned protective layer corresponds to a first region of the semiconductor epitaxial wafer, and a second region of the semiconductor epitaxial wafer is located at the periphery of the first region. S14, performing an etching process to remove the semiconductor epitaxial wafer located in the second region; S15, performing a selective etching process to remove the patterned protection layer, the lower confinement layer and the upper confinement layer are etched inward along a direction perpendicular to the epitaxial growth direction, corresponding to obtain a first pillar layer and a second pillar layer; the edge of the active layer extends out of the first pillar layer and the second pillar layer to form a suspended structure, obtaining a first micro-disk layer; the edge of the electrode contact layer extends out of the second pillar layer to form a suspended structure, obtaining a second micro-disk layer; S2, coating a planarization material outside the substrate, the optical microcavity unit and the electrical connection unit, etching the planarization material to make the planarization material form a continuous planar structure adhering to the side surface of the electrical connection unit opposite to the optical microcavity unit, obtaining a planarization unit; S3, preparing a first electrode on the continuous planar surface in contact with the electrical connection unit, obtaining a micro-disk laser.

8. The preparation method according to claim 7, characterized in that, The step S3 further comprises: Preparation of a second electrode on the side of the substrate opposite to the optical microcavity unit.

9. The preparation method according to claim 8, characterized in that, The step S14 comprises: Performing a wet etching process, immersing the semiconductor epitaxial wafer in a wet etching solution along the epitaxial growth direction, removing the semiconductor epitaxial wafer located in the second region, and the immersion depth of the electrode contact layer to the lower confinement layer in the wet etching solution decreases in turn.

10. The production method according to claim 8 or 9, characterized by, The step S14 further comprises: Performing an etching process to partially etch the substrate located in the second region to form a protrusion on the substrate in contact with the lower confinement layer.

11. The preparation method according to claim 7, characterized in that, The step S2 comprises: Etching the planarization material to expose the electrical connection unit; continue etching the exposed area of the electrical connection unit to make the side surface of the electrical connection unit opposite to the optical microcavity unit adhere to the planarization material to form a continuous planar structure.

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