Switchable Cavity Surface Emitting Laser

Abstract

The present invention relates to the field of semiconductor lasers, and in particular to a surface-emitting laser with a convertible cavity type, comprising a resonant cavity conversion control electrode, a substrate, a dielectric film waveguide layer, a second resonant cavity active layer, an N-type electrode, a tunnel junction, a resonant cavity conversion control layer, an N-type DBR layer, a first resonant cavity active layer, an oxide layer, a P-type DBR layer and a P-type electrode stacked in sequence from bottom to top; the N-type DBR layer, the first resonant cavity active layer and the P-type DBR layer constitute a first resonant cavity; the dielectric film waveguide layer, the second resonant cavity active layer and the P-type DBR layer constitute a second resonant cavity; and the resonant cavity conversion control layer uses an electro-optical material. The present invention can realize the switching of lasers between two resonant cavities, change the oscillation path of the laser in the resonant cavity, and can also adjust the polarization characteristics of the material and change the polarization state of the laser.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor lasers, and in particular relates to a surface-emitting laser with a convertible cavity type. Background Art

[0002] Vertical cavity surface emitting lasers play an important role in optical communication, spectral analysis, laser imaging, laser processing and other fields. Vertical cavity surface emitting lasers have the characteristics of short effective cavity length, which makes the laser have good single longitudinal mode characteristics. At present, mature vertical cavity surface emitting lasers mainly realize the dual limitation of electric field and optical field through oxidation confinement structure. Generally, when the current limiting hole is less than 4μm, the output laser is a single-mode beam. However, a smaller current limiting hole will limit the output power, and the wavelength tuning range is small. The microcavity structure has a short cavity length, resulting in a larger line width of the device. Summary of the invention

[0003] In view of this, the present invention aims to provide a surface emitting laser with a convertible cavity type to solve the technical problems of the existing vertical cavity surface emitting laser having low power, small wavelength tuning range and large line width when single-mode output.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] A surface emitting laser with a convertible cavity type comprises a horizontal resonant cavity conversion control electrode, a horizontal substrate, a horizontal dielectric film waveguide layer, a horizontal second resonant cavity active layer, a horizontal N-type electrode, a horizontal resonant cavity conversion control layer, a horizontal N-type DBR layer, a horizontal first resonant cavity active layer, a horizontal oxide layer, a horizontal P-type DBR layer and a horizontal P-type electrode which are sequentially stacked from bottom to top; the horizontal N-type DBR layer, the horizontal first resonant cavity active layer and the horizontal P-type DBR layer constitute a horizontal first resonant cavity; the horizontal dielectric film waveguide layer, the horizontal second resonant cavity active layer and the horizontal P-type DBR layer constitute a second resonant cavity; the horizontal resonant cavity conversion control layer adopts an electro-optical material, and based on the electro-optical effect of the electro-optical material, the laser is switched between the horizontal first resonant cavity and the horizontal second resonant cavity.

[0006] Furthermore, a tunnel junction is prepared between the horizontal resonant cavity conversion control layer and the horizontal N-type electrode.

[0007] Furthermore, a surface relief grating is prepared on the horizontal P-type DBR layer at a position corresponding to the light exit hole.

[0008] Furthermore, the material components of the horizontal first resonant cavity active layer and the horizontal second resonant cavity active layer are the same or different.

[0009] Furthermore, the electro-optical material is potassium dihydrogen phosphate crystal, ammonium dihydrogen phosphate crystal, lithium niobate crystal, barium titanate crystal or electro-optical ceramic.

[0010] A surface emitting laser with a switchable cavity type comprises a tilted substrate, a tilted epitaxial structure is prepared on the top surface of the tilted substrate, the tilted epitaxial structure comprises a tilted dielectric film waveguide layer, a tilted second resonant cavity active layer, a wedge-shaped spacer layer, a tilted N-type electrode, a tilted resonant cavity conversion control layer, a tilted N-type DBR layer, a tilted first resonant cavity active layer, a tilted oxide layer and a tilted P-type DBR layer, a tilted P-type electrode is prepared on the top surface of the tilted epitaxial structure, a horizontal resonant cavity conversion control electrode is prepared on the bottom surface of the tilted substrate, and a reflective layer is prepared on the side surface of the tilted epitaxial structure; the tilted N-type DBR layer, the tilted first resonant cavity active layer and the tilted P-type DBR layer constitute a tilted first resonant cavity; the tilted dielectric film waveguide layer, the tilted second resonant cavity active layer and the tilted P-type DBR layer constitute a tilted second resonant cavity; the tilted resonant cavity conversion control layer adopts an electro-optical material, and based on the electro-optical effect of the electro-optical material, the laser is switched between the tilted first resonant cavity and the tilted second resonant cavity.

[0011] Furthermore, a surface relief grating is prepared on the inclined P-type DBR layer at a position corresponding to the light exit hole.

[0012] Furthermore, the material components of the inclined first resonant cavity active layer and the inclined second resonant cavity active layer are the same or different.

[0013] Furthermore, the electro-optical material is potassium dihydrogen phosphate crystal, ammonium dihydrogen phosphate crystal, lithium niobate crystal, barium titanate crystal or electro-optical ceramic.

[0014] Furthermore, the reflective layer is made of AlGaAs, GaAs, TiO2 or Ta2O5 material.

[0015] Compared with the prior art, the invention can achieve the following beneficial effects:

[0016] 1. The present invention introduces a resonant cavity conversion control layer, which adjusts the characteristics of the electro-optical material by changing the injected current, so that the resonant cavity conversion control layer is light-transmitting or light-reflecting, thereby realizing the switching of the laser between the first resonant cavity and the second resonant cavity, changing the oscillation path of the laser in the resonant cavity, and at the same time adjusting the polarization characteristics of the material to change the polarization state of the laser.

[0017] 2. The second resonant cavity effectively increases the cavity length, enabling wide-range tuning of the wavelength while narrowing the linewidth.

[0018] 3. The Z-type resonant cavity further extends the propagation path of the laser and further increases the effective cavity length of the resonant cavity, thereby achieving line width narrowing and power improvement of the laser.

[0019] 4. When the two active layers use the same material composition, the output power can be increased while achieving single-mode output; when the two active layers use different material compositions, dual-wavelength output can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0021] Figure 1 It is a schematic structural diagram of the surface-emitting laser with a switchable cavity as described in Example 1 of the present invention.

[0022] Figure 2 It is a schematic structural diagram of the surface-emitting laser with a switchable cavity as described in Example 2 of the present invention.

[0023] Description of the accompanying drawings of Example 1: horizontal resonant cavity conversion control electrode 101, horizontal substrate 102, horizontal dielectric film waveguide layer 103, horizontal second resonant cavity active layer 104, horizontal N-type electrode 105, horizontal resonant cavity conversion control layer 106, horizontal N-type DBR layer 107, horizontal first resonant cavity active layer 108, horizontal oxide layer 109, horizontal P-type DBR layer 110, horizontal P-type electrode 111, tunnel junction 112.

[0024] Description of the reference numerals of Example 2: inclined substrate 201, inclined dielectric film waveguide layer 202, inclined second resonant cavity active layer 203, wedge-shaped spacer layer 204, inclined N-type electrode 205, inclined resonant cavity conversion control layer 206, inclined N-type DBR layer 207, inclined first resonant cavity active layer 208, inclined oxide layer 209, inclined P-type DBR layer 210, inclined P-type electrode 211, horizontal resonant cavity conversion control electrode 212, and reflective layer 213. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0026] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0029] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0030] Example 1

[0031] like Figure 1 As shown, the present invention provides a surface emitting laser with a convertible cavity type in Example 1. The surface emitting laser is a vertical cavity, specifically including a horizontal resonant cavity conversion control electrode 101, a horizontal substrate 102, a horizontal dielectric film waveguide layer 103, a horizontal second resonant cavity active layer 104, a horizontal N-type electrode 105, a horizontal resonant cavity conversion control layer 106, a horizontal N-type DBR layer 107, a horizontal first resonant cavity active layer 108, a horizontal oxide layer 109, a horizontal P-type DBR layer 110 and a horizontal P-type electrode 111 stacked in sequence from bottom to top.

[0032] The horizontal N-type DBR layer 107, the horizontal first resonant cavity active layer 108 and the horizontal P-type DBR layer 110 constitute a horizontal first resonant cavity. The laser constituted by the horizontal first resonant cavity is a traditional vertical cavity surface emitting laser. The cavity length of the horizontal first resonant cavity is the distance between the horizontal N-type DBR layer 107 and the horizontal P-type DBR layer 110.

[0033] The horizontal dielectric film waveguide layer 103, the horizontal second resonant cavity active layer 104 and the horizontal P-type DBR layer 110 constitute a horizontal second resonant cavity. The cavity length of the horizontal second resonant cavity is the distance between the horizontal dielectric film waveguide layer 103 and the horizontal P-type DBR layer 110. It can be seen that the effective cavity length of the horizontal second resonant cavity is greater than the effective cavity length of the horizontal first resonant cavity.

[0034] The horizontal resonant cavity conversion control layer 106 is made of electro-optical materials, including but not limited to potassium dihydrogen phosphate crystals, ammonium dihydrogen phosphate crystals, lithium niobate crystals, barium titanate crystals, electro-optic ceramics and other materials, and the switching of the laser between the horizontal first resonant cavity and the horizontal second resonant cavity is realized based on the electro-optical effect of the electro-optical material. Specifically, by changing the injection current of the horizontal P-type electrode 111 and the horizontal resonant cavity conversion control electrode 101, the characteristics of the electro-optical material are adjusted to make the horizontal resonant cavity conversion control layer 106 transparent or reflective. When the horizontal resonant cavity conversion control layer 106 is transparent, the laser oscillates in the horizontal second resonant cavity. When the horizontal resonant cavity conversion control layer 106 is reflective, the laser oscillates in the horizontal first resonant cavity, thereby realizing the switching of the laser between the horizontal first resonant cavity and the horizontal second resonant cavity. When the laser oscillates in the horizontal second resonant cavity, relative to the horizontal first resonant cavity, the propagation path of the laser is extended, so that the line width of the laser is compressed, and the tuning range of the wavelength is increased, and the polarization state of the laser is changed at the same time.

[0035] When the horizontal second resonant cavity active layer 104 and the horizontal first resonant cavity active layer 108 use the same material composition, the output power can be increased under a smaller current limiting hole, that is, high power can be achieved while outputting in a single mode; when the horizontal second resonant cavity active layer 104 and the horizontal first resonant cavity active layer 108 use different material compositions, dual-wavelength output can be achieved.

[0036] In order to ensure uniform current injection into the horizontal second resonant cavity active layer 104 , a tunnel junction 112 is prepared between the horizontal resonant cavity conversion control layer 106 and the horizontal N-type electrode 105 . The tunnel junction 112 is made of heavily doped AlGaAs, InP and other materials.

[0037] A surface relief grating (not shown) is prepared on the surface of the horizontal P-type DBR layer 110 at a position corresponding to the light exit hole to achieve the selection of the laser mode.

[0038] A method for preparing a surface-emitting laser with a switchable cavity type comprises the following steps:

[0039] S1: Growing a SiO2 / Ta2O5 dielectric film on a horizontal substrate 102 (using an N-type GaAs substrate) to form a horizontal dielectric film waveguide layer 103.

[0040] S2: Depositing GaAs / Al on the horizontal dielectric film waveguide layer 103 0.3 Ga 0.7 As quantum well structure, forming a horizontal second resonant cavity active layer 104.

[0041] S3: growing a horizontal N-type electrode 105 on the horizontal second resonant cavity active layer 104, and preparing electrode holes by photolithography.

[0042] S4: A tunnel junction 112 is epitaxially grown for a second time on the horizontal second resonant cavity active layer 104 where the electrode holes are formed.

[0043] S5: growing electro-optical material on the tunnel junction 112 to form a horizontal resonant cavity conversion control layer 106 .

[0044] S6: Alternately grow 12 pairs of Al on the horizontal resonant cavity conversion control layer 106 0.3 Ga 0.7 As and Al 0.9 Ga 0.1 As, a horizontal N-type DBR layer 107 is formed.

[0045] S7: Growing GaAs / Al on the horizontal N-type DBR layer 107 0.3 Ga 0.7 As quantum well structure, forming a horizontal first resonant cavity active layer 108.

[0046] S8: Growing Al on the horizontal first resonant cavity active layer 108 0.98 Ga 0.02 As, a horizontal oxide layer 109 is formed.

[0047] S9: Alternately grow 26 pairs of Al on the horizontal oxide layer 109 0.3 Ga 0.7 As and Al 0.9 Ga 0.1 As, a horizontal P-type DBR layer 110 is formed.

[0048] S10: performing photolithography on the epitaxial wafer structure to form a circular terrace and expose the horizontal oxide layer 109 , and performing wet oxidation process to oxidize the horizontal oxide layer 109 to form a current limiting hole.

[0049] S11: growing a horizontal P-type electrode 111 on the top surface of the epitaxial wafer structure.

[0050] S12: Thinning and polishing the horizontal substrate 102, and growing the horizontal resonant cavity conversion control electrode 101.

[0051] Example 2

[0052] like Figure 2 As shown, the present invention creates a surface emitting laser with a convertible cavity type, which is a Z-type cavity, including an inclined substrate 201, and a tilted epitaxial structure is prepared on the top surface of the inclined substrate 201. The tilted epitaxial structure includes an inclined dielectric film waveguide layer 202, an inclined second resonant cavity active layer 203, a wedge-shaped spacer layer 204, an inclined N-type electrode 205, a tilted resonant cavity conversion control layer 206, an inclined N-type DBR layer 207, an inclined first resonant cavity active layer 208, an inclined oxide layer 209, and an inclined P-type DBR layer 210. An inclined P-type electrode 211 is prepared on the top surface of the inclined epitaxial structure, a horizontal resonant cavity conversion control electrode 212 is prepared on the bottom surface of the inclined substrate 201, and a reflective layer 213 is prepared on the side of the inclined epitaxial structure.

[0053] The material of the wedge-shaped spacer layer 204 is selected according to the material system of the laser, and the present embodiment 2 uses AlGaAs material.

[0054] The inclined N-type DBR layer 207, the inclined first resonant cavity active layer 208 and the inclined P-type DBR layer 210 constitute an inclined first resonant cavity; the inclined dielectric film waveguide layer 202, the inclined second resonant cavity active layer 203 and the inclined P-type DBR layer 210 constitute an inclined second resonant cavity; the effective cavity length of the inclined second resonant cavity is greater than the effective cavity length of the inclined first resonant cavity.

[0055] The tilted resonant cavity conversion control layer 206 is made of electro-optical material, and the switching of the laser between the tilted first resonant cavity and the tilted second resonant cavity is achieved based on the electro-optical effect of the electro-optical material.

[0056] The reflective layer 213 is made of a material having a light beam reflection function such as AlGaAs / GaAs / TiO2 / Ta2O5 to reflect the laser, and the laser is emitted from the light exit hole after being reflected by the reflective layer 213 .

[0057] In Example 2, the inclined second resonant cavity is configured as a Z-shaped cavity, which further increases the effective cavity length compared to the vertical cavity in Example 1, so that the propagation path of the laser is further extended, thereby further narrowing the laser line width and further improving the power.

[0058] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0059] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A surface-emitting laser with a switchable cavity type, characterized in that: It includes a horizontal resonant cavity conversion control electrode, a horizontal substrate, a horizontal dielectric film waveguide layer, a horizontal second resonant cavity active layer, a horizontal N-type electrode, a horizontal resonant cavity conversion control layer, a horizontal N-type DBR layer, a horizontal first resonant cavity active layer, a horizontal oxide layer, a horizontal P-type DBR layer and a horizontal P-type electrode stacked in sequence from bottom to top; The horizontal N-type DBR layer, the horizontal first resonant cavity active layer and the horizontal P-type DBR layer constitute the first resonant cavity; the horizontal dielectric film waveguide layer, the horizontal second resonant cavity active layer and the horizontal P-type DBR layer constitute the second resonant cavity; the horizontal resonant cavity conversion control layer adopts electro-optical material, and the switching of laser between the horizontal first resonant cavity and the horizontal second resonant cavity is realized based on the electro-optical effect of the electro-optical material.

2. The switchable cavity surface emitting laser according to claim 1, characterized in that: A tunnel junction is prepared between the horizontal resonant cavity conversion control layer and the horizontal N-type electrode.

3. The switchable cavity surface emitting laser according to claim 1, characterized in that: A surface relief grating is prepared on the horizontal P-type DBR layer at a position corresponding to the light exit hole.

4. The switchable cavity surface emitting laser according to claim 1, characterized in that: The material components of the horizontal first resonant cavity active layer and the horizontal second resonant cavity active layer are the same or different.

5. The switchable cavity surface emitting laser according to claim 1, characterized in that: The electro-optic material is potassium dihydrogen phosphate crystal, ammonium dihydrogen phosphate crystal, lithium niobate crystal, barium titanate crystal or electro-optic ceramic.

6. A surface-emitting laser with a switchable cavity type, characterized in that: The invention comprises an inclined substrate, and an inclined epitaxial structure is prepared on the top surface of the inclined substrate, wherein the inclined epitaxial structure comprises an inclined dielectric film waveguide layer, an inclined second resonant cavity active layer, a wedge-shaped spacer layer, an inclined N-type electrode, an inclined resonant cavity conversion control layer, an inclined N-type DBR layer, an inclined first resonant cavity active layer, an inclined oxide layer and an inclined P-type DBR layer, an inclined P-type electrode is prepared on the top surface of the inclined epitaxial structure, a horizontal resonant cavity conversion control electrode is prepared on the bottom surface of the inclined substrate, and a reflective layer is prepared on the side surface of the inclined epitaxial structure; the inclined N-type DBR layer, the inclined first resonant cavity active layer and the inclined P-type DBR layer constitute an inclined first resonant cavity; the inclined dielectric film waveguide layer, the inclined second resonant cavity active layer and the inclined P-type DBR layer constitute an inclined second resonant cavity; the inclined resonant cavity conversion control layer adopts electro-optical material, and the switching of laser between the inclined first resonant cavity and the inclined second resonant cavity is realized based on the electro-optical effect of the electro-optical material.

7. The switchable cavity surface emitting laser according to claim 6, characterized in that: A surface relief grating is prepared on the inclined P-type DBR layer at a position corresponding to the light exit hole.

8. The switchable cavity surface emitting laser according to claim 6, characterized in that: The material components of the inclined first resonant cavity active layer and the inclined second resonant cavity active layer are the same or different.

9. The switchable cavity surface emitting laser according to claim 6, characterized in that: The electro-optic material is potassium dihydrogen phosphate crystal, ammonium dihydrogen phosphate crystal, lithium niobate crystal, barium titanate crystal or electro-optic ceramic.

10. The switchable cavity surface emitting laser according to claim 6, characterized in that: The reflective layer is made of AlGaAs, GaAs, TiO2 or Ta2O5 material.

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