A vertical cavity surface emitting laser and a manufacturing method thereof

Abstract

The present application discloses a vertical cavity surface emitting laser (VCSEL) and its manufacturing method, which relates to the field of semiconductor lasers. The VCSEL comprises a substrate; a VCSEL epitaxial structure disposed on the upper surface of the substrate; an insulating layer disposed on the upper surface of the VCSEL epitaxial structure; a temperature measuring electrode disposed on the outer side of a switching electrode, for applying a voltage opposite to that of the switching electrode; the temperature measuring electrode comprising a first temperature measuring electrode disposed on the upper surface of the VCSEL epitaxial structure and a second temperature measuring electrode disposed at the bottom of an isolation trench; and a degaussing coil electrode disposed on the upper surface of the insulating layer and located outside the temperature measuring electrode, for passing a current to generate a magnetic field of equal magnitude and opposite direction to the total magnetic field generated by the switching electrode, the temperature measuring electrode, and the VCSEL. By providing the temperature measuring electrode and the degaussing coil electrode, the present application enables the VCSEL to achieve self-temperature testing and overall non-magnetism without the need for additional components, thereby reducing manufacturing costs and improving manufacturing efficiency, while maintaining chip-level volume.

Description

Technical Field

[0001] The present application relates to the field of semiconductor lasers, and in particular to a vertical cavity surface emitting laser and a manufacturing method thereof. Background Art

[0002] Vertical-cavity surface-emitting lasers (VCSELs) can be used in quantum precision measurement technology. For example, they can be used as pumping and detection light sources in atomic gyroscopes and integrated into atomic gas chambers.

[0003] When working, current flows inside the test electrode and switch electrode of VCSEL, which inevitably generates a magnetic field. The direction and magnitude of the magnetic field are related to the direction and magnitude of the current flow, and eventually form a total magnetic field. Typical quantum precision measurement instruments such as atomic gyroscopes and atomic magnetometers that work on the principle of nuclear magnetic resonance need to detect changes in the magnetic field, so the instrument itself is required to be non-magnetic. Therefore, it is necessary to perform additional modular packaging on the VCSEL, and to achieve non-magnetized packaging by generating a magnetic field that can offset the direction of the VCSEL's own magnetic field through an additional substrate. In addition, in order to achieve compact packaging and reduce the volume of the instrument, the VCSEL must work in an environment close to the temperature of the atomic gas chamber. The temperature of the atomic gas chamber is usually ≥70°C, but the current VCSEL itself cannot achieve temperature measurement and needs to be achieved through an additional temperature measuring device. The above-mentioned methods of offsetting the VCSEL's own magnetic field and measuring the VCSEL's temperature require the use of additional components, which not only increases the production cost of the VCSEL and reduces the production efficiency, but also reduces the size of the VCSEL from the chip volume (μm 3 ) size becomes the module volume size (cm 3 ), which means that quantum precision measurement instruments such as atomic gyroscopes and atomic magnetometers cannot be integrated into chips at present.

[0004] Therefore, how to solve the above technical problems should be the focus of those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a vertical cavity surface emitting laser and a manufacturing method thereof, so that the vertical cavity surface emitting laser itself does not have magnetism and can achieve temperature measurement, thereby reducing the manufacturing cost, improving the manufacturing efficiency and reducing the volume.

[0006] To solve the above technical problems, the present application provides a vertical cavity surface emitting laser, comprising:

[0007] substrate;

[0008] a VCSEL epitaxial structure provided on the upper surface of the substrate;

[0009] an insulating layer provided on the upper surface of the VCSEL epitaxial structure;

[0010] A temperature measuring electrode provided outside the switch electrode, for applying a voltage opposite to that of the switch electrode; the temperature measuring electrode comprises a first temperature measuring electrode provided on the upper surface of the VCSEL epitaxial structure, and a second temperature measuring electrode provided at the bottom of the isolation trench;

[0011] The degaussing coil electrode is provided on the upper surface of the insulating layer and outside the temperature measuring electrode, and is used to pass current to generate a magnetic field that is equal in magnitude and opposite in direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode and the vertical cavity surface emitting laser.

[0012] Optionally, also include:

[0013] an elliptical microlens provided on the upper surface of the VCSEL epitaxial structure;

[0014] a dielectric film layer provided on the surface of the elliptical microlens;

[0015] The angles between the major axis of the elliptical microlens and the

[110] and [-110] crystal directions are both 45°, and the elliptical microlens, the dielectric film layer and the P-type DBR layer in the VCSEL epitaxial structure together serve as the top reflector of the vertical cavity surface emitting laser.

[0016] Optionally, the number of film layers included in the P-type DBR layer is less than 20 pairs.

[0017] Optionally, the dielectric film layer includes alternately stacked silicon dioxide layers and silicon nitride layers.

[0018] Optionally, also include:

[0019] The heating coil electrode is provided on the upper surface of the insulating layer and located inside the degaussing coil electrode, and is used for passing current to generate heat so as to heat the vertical cavity surface emitting laser.

[0020] Optionally, the P-type cap layer in the VCSEL epitaxial structure includes a doped GaAs layer and an intrinsic GaAs layer stacked from bottom to top, wherein the thickness of the intrinsic GaAs layer is three quarters of the optical thickness.

[0021] Optionally, the switch electrode, the temperature measuring electrode, and the degaussing coil electrode are all ring-shaped.

[0022] The present application also provides a method for manufacturing a vertical cavity surface emitting laser, comprising:

[0023] Growing a VCSEL epitaxial structure on the upper surface of the substrate;

[0024] Growing an insulating layer on the upper surface of the VCSEL epitaxial structure;

[0025] growing switch electrodes, temperature measuring electrodes and degaussing coil electrodes to obtain a vertical cavity surface emitting laser;

[0026] The temperature measuring electrode is located outside the switch electrode, and includes a first temperature measuring electrode provided on the upper surface of the VCSEL epitaxial structure and a second temperature measuring electrode provided at the bottom of the isolation trench. The temperature measuring electrode is used to apply a voltage opposite to that of the switch electrode.

[0027] The degaussing coil electrode is located on the upper surface of the insulating layer; the degaussing coil electrode is located outside the temperature measuring electrode and is used to pass current to generate a magnetic field that is equal in magnitude and opposite in direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode and the vertical cavity surface emitting laser.

[0028] Optionally, before growing the switch electrode, the temperature measuring electrode and the degaussing coil electrode, the following is further included:

[0029] preparing an elliptical microlens on the upper surface of the VCSEL epitaxial structure;

[0030] depositing a dielectric film layer on the surface of the elliptical microlens;

[0031] The angles between the major axis of the elliptical microlens and the

[110] and [-110] crystal directions are both 45°, and the elliptical microlens, the dielectric film layer and the P-type DBR layer in the VCSEL epitaxial structure together serve as the top reflector of the vertical cavity surface emitting laser.

[0032] Optionally, also include:

[0033] A heating coil electrode is grown on the upper surface of the insulating layer; the heating coil electrode is located inside the degaussing coil electrode and is used to pass current to generate heat to heat the vertical cavity surface emitting laser.

[0034] A vertical cavity surface emitting laser (VCSEL) provided in the present application includes: a substrate; a VCSEL epitaxial structure provided on the upper surface of the substrate; an insulating layer provided on the upper surface of the VCSEL epitaxial structure; a temperature measuring electrode provided on the outer side of a switch electrode, for applying a voltage opposite to that of the switch electrode; the temperature measuring electrodes including a first temperature measuring electrode provided on the upper surface of the VCSEL epitaxial structure and a second temperature measuring electrode provided at the bottom of an isolation trench; and a degaussing coil electrode provided on the upper surface of the insulating layer and located outside the temperature measuring electrode, for passing a current to generate a magnetic field of equal magnitude and opposite direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode, and the VCSEL.

[0035] As can be seen, the VCSEL in this application is provided with temperature-measuring electrodes. The temperature-measuring electrodes include a first temperature-measuring electrode disposed on the upper surface of the VCSEL epitaxial structure and a second temperature-measuring electrode disposed at the bottom of the isolation trench. A voltage opposite to that of the switch electrode is applied to both sides of the first and second temperature-measuring electrodes. Utilizing the PN junction characteristics of the VCSEL epitaxial structure, a semiconductor Peltier effect is formed between the first and second temperature-measuring electrodes. When the temperature inside the VCSEL changes, corresponding current changes are generated on both sides of the first and second temperature-measuring electrodes. By detecting the magnitude of the reverse current change between the first and second temperature-measuring electrodes, the VCSEL's own temperature test can be achieved. In addition, in this application, a degaussing coil electrode is also disposed outside the temperature-measuring electrode and the switch electrode. Using the principle of electromagnetic induction, a magnetic field is generated when a current is passed through the degaussing coil electrode. This magnetic field is equal in magnitude and opposite in direction to the total magnetic field generated by the temperature-measuring electrode and the switch electrode, thereby rendering the VCSEL as a whole non-magnetic. That is, the vertical cavity surface emitting laser in this application does not require additional components to achieve temperature measurement and demagnetization, which reduces production costs and improves production efficiency, while keeping its volume at the chip level.

[0036] In addition, the present application also provides a manufacturing method having the above advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions of the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0038] Figure 1 A schematic structural diagram of a vertical cavity surface emitting laser provided in an embodiment of the present application;

[0039] Figure 2 A schematic structural diagram of another vertical cavity surface emitting laser provided in an embodiment of the present application;

[0040] Figure 3 for Figure 2 A top view of the vertical cavity surface emitting laser shown;

[0041] Figure 4 A schematic structural diagram of another vertical cavity surface emitting laser provided in an embodiment of the present application;

[0042] Figure 5 for Figure 4 A top view of the vertical cavity surface emitting laser shown;

[0043] Figure 6 A flowchart of a method for manufacturing a vertical cavity surface emitting laser provided in an embodiment of the present application;

[0044] Figure 7 A partial schematic diagram of a second photolithography pattern provided in an embodiment of the present application;

[0045] In the figure, 1. substrate, 2. N-type DBR layer, 3. active layer, 4. oxide layer, 5. P-type DBR layer, 6. P-type cap layer, 7. isolation channel, 8. oxide aperture, 9. insulating layer, 10. degaussing coil electrode, 11. first temperature measuring electrode, 12. second temperature measuring electrode, 13. P-type switch electrode, 14. N-type switch electrode, 15. elliptical microlens, 16. dielectric film layer, 17. heating coil electrode, 101. opaque layer, 102. translucent layer. DETAILED DESCRIPTION

[0046] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only a part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative efforts are within the scope of protection of the present application.

[0047] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0048] As described in the background technology section, current flows inside the test electrodes and switch electrodes of the VCSEL during operation, which inevitably generates a magnetic field. In addition, the VCSEL itself cannot measure temperature. In order to offset the magnetic field generated by the VCSEL itself and measure temperature, additional components are required. This not only increases the production cost of the VCSEL and reduces production efficiency, but also makes the VCSEL larger.

[0049] In view of this, the present application provides a vertical cavity surface emitting laser, please refer to Figure 1 ,include:

[0050] Substrate 1;

[0051] A VCSEL epitaxial structure provided on the upper surface of the substrate 1;

[0052] an insulating layer 9 provided on the upper surface of the VCSEL epitaxial structure;

[0053] A temperature measuring electrode provided outside the switch electrode, for applying a voltage opposite to that of the switch electrode; the temperature measuring electrode comprises a first temperature measuring electrode 11 provided on the upper surface of the VCSEL epitaxial structure, and a second temperature measuring electrode 12 provided at the bottom of the isolation trench 7;

[0054] The degaussing coil electrode 10 provided on the upper surface of the insulating layer 9 and outside the temperature measuring electrode is used to pass current to generate a magnetic field that is equal in magnitude and opposite in direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode and the vertical cavity surface emitting laser.

[0055] It should be noted that the VCSEL further includes an oxidation aperture 8 located in the oxidation layer 4. The diameter of the oxidation aperture 8 may be 5 to 20 microns. The VCSEL chip may be square in shape with a side length of 500 to 5000 microns.

[0056] The first temperature measuring electrode 11 is an N-type temperature measuring electrode, and the second electrode is a P-type temperature measuring electrode. The thickness of the first and second temperature measuring electrodes 11 and 12 can range from 200 to 500 nanometers, and the material can be an alloy formed from metals such as titanium, platinum, gold, nickel, and germanium. The N-type temperature measuring electrode is located on the surface of the VCSEL, and the P-type temperature measuring electrode is located at the bottom of the isolation trench 7.

[0057] The temperature measuring electrode is located outside the switching electrode. By applying a voltage opposite to the switching electrode to the temperature measuring electrode and utilizing the PN junction characteristics of the VCSEL epitaxial structure, the semiconductor Peltier effect is generated between the first temperature measuring electrode 11 and the second temperature measuring electrode 12. Then, by detecting the reverse current change between the first temperature measuring electrode 11 and the second temperature measuring electrode 12, the self-temperature test of the vertical cavity surface emitting laser is realized.

[0058] The degaussing coil electrode 10 is located on the surface of the VCSEL. The coil width can be 10 microns to 100 microns, the thickness can be 100 nanometers to 500 nanometers, the number of turns can be 2 to 20, and the material can be an alloy formed by metal titanium, platinum, gold, nickel, germanium, etc.

[0059] During operation, current flows through the switch and temperature measurement electrodes, generating a magnetic field. The direction and magnitude of the magnetic field are related to the direction and magnitude of the current flow, ultimately forming a total magnetic field. The degaussing coil electrode 10 also generates a magnetic field when current flows through it. By controlling the magnitude and direction of the current, the magnetic field generated by the degaussing coil electrode 10 is equal in magnitude and opposite in direction to the total magnetic field generated by the switch and temperature measurement electrodes, rendering the VCSEL emitter non-magnetic.

[0060] The substrate 1 may be an N-type GaAs substrate.

[0061] The VCSEL epitaxial structure includes an N-type DBR (distributed bragg reflector mirror) layer 2, an active layer 3, an oxide layer 4, a P-type DBR layer 5 and a P-type cap layer 6 stacked in sequence on a substrate 1.

[0062] The N-type DBR layer 2 includes alternately grown AlGaAs layers with different Al compositions. Each pair of DBRs contains two AlGaAs layers with different Al compositions. The Al composition of each AlGaAs layer can be between 0.05 and 1, and the thickness of each AlGaAs layer can be one-quarter of the optical thickness. Depending on the operating wavelength of the VCSEL, the thickness of each AlGaAs layer ranges from 0.01 microns to 1 micron, the dopant is Si, and the doping concentration is 1E16 to 8E18 / cm 3 The total number of pairs of the N-type DBR layer 2 is 20 to 40 pairs, and the thickness of the N-type DBR layer 2 can be 2 micrometers to 8 micrometers.

[0063] Active layer 3 can be an InAlGaAs / AlGaAs layer. Active layer 3 is an intrinsic material. Depending on the designed operating wavelength, the In composition can range from 0 to 0.2, and the Al composition can range from 0 to 0.9. The thickness of active layer 3 can range from 3 nanometers to 300 nanometers, enabling an operating wavelength range of 600 nanometers to 1200 nanometers.

[0064] The oxide layer 4 may be an AlGaAs layer, the Al content may be 0.95-1, the thickness of the oxide layer 4 may be 10 nm-50 nm, the dopant may be C, and the doping concentration may be 1E15-1E17 / cm 3 .

[0065] The P-type DBR layer 5 includes alternately grown AlGaAs layers with different Al compositions. Each pair of DBRs contains two AlGaAs layers with different Al compositions. The Al composition of each AlGaAs layer can be between 0.05 and 1, and the thickness of each AlGaAs layer can be one-quarter of the optical thickness. Depending on the operating wavelength of the VCSEL, the thickness of each AlGaAs layer can range from 0.01 microns to 1 micron, the dopant can be C, and the doping concentration can be 1E16 to 8E18 / cm 3 .

[0066] The P-type cap layer 6 includes a doped GaAs layer and an intrinsic GaAs layer stacked from bottom to top, wherein the thickness of the intrinsic GaAs layer is three-quarters of the optical thickness. The doped GaAs layer contacts the P-type DBR layer 5, and the thickness of the doped GaAs layer is one-quarter of the optical thickness. Depending on the operating wavelength of the VCSEL, the thickness range can be 30 nm to 200 nm, the dopant can be C, and the doping concentration can be 1E18 to 8E18 / cm 3 The intrinsic GaAs layer has a thickness of three-quarters of the optical thickness to facilitate modulation, ranging from 90 nm to 600 nm depending on the VCSEL operating wavelength. The optical thickness is the product of the operating wavelength and the refractive index.

[0067] The isolation channel 7 is annular, and the inner diameter of the isolation channel 7 can be 20 microns to 50 microns, and the width of the isolation channel 7 can be 30 microns to 100 microns. It is produced on the surface of the VCSEL epitaxial structure through an etching process. The etching depth of the isolation channel 7 is from the surface of the VCSEL epitaxial structure to expose the substrate 1. Depending on the VCSEL epitaxial structure, the etching depth can range from 5 microns to 20 microns.

[0068] The insulating layer 9 may be a silicon dioxide layer, and the thickness may be 100 nm to 500 nm.

[0069] The switch electrodes include a P-type switch electrode 13 and an N-type switch electrode 14. The P-type switch electrode 13 is located on the surface of the VCSEL, and the N-type switch electrode 14 is located at the bottom of the isolation trench 7. The switch electrodes can be 200 to 500 nanometers thick and can be made of alloys such as titanium, platinum, gold, nickel, and germanium.

[0070] Electrode contacts are provided at the ends of the P-type switch electrode 13 , the N-type switch electrode 14 , the N-type temperature measuring electrode, the P-type temperature measuring electrode, and the degaussing coil electrode 10 .

[0071] The working principle of the vertical cavity surface emitting laser is as follows: current is applied on both sides of the P-type switch electrode 13 and the N-type switch electrode 14. The current flows into the active layer 3 through the oxidation aperture 8 to generate optical gain. The light emitted by the active layer 3 oscillates and amplifies between the N-type DBR layer 2 and the P-type DBR layer 5. When the threshold current is reached, the laser is emitted.

[0072] It should be noted that the present application does not limit the shapes of the switch electrode, temperature measuring electrode, and degaussing coil electrode 10 and can be customized. Optionally, the switch electrode, temperature measuring electrode, and degaussing coil electrode 10 can all be annular, or square, etc. When the switch electrode, temperature measuring electrode, and degaussing coil electrode 10 are all annular, right-angle bends can be avoided, thereby reducing the resistance of each electrode.

[0073] The VCSEL in this application is equipped with temperature-measuring electrodes. These include a first temperature-measuring electrode 11 disposed on the upper surface of the VCSEL epitaxial structure and a second temperature-measuring electrode 12 disposed at the bottom of the isolation trench 7. A voltage opposite to that of the switch electrode is applied to the first and second temperature-measuring electrodes 11, 12. Leveraging the PN junction characteristics of the VCSEL epitaxial structure, a semiconductor Peltier effect is generated between the first and second temperature-measuring electrodes 11, 12. When the temperature inside the VCSEL changes, corresponding current changes occur across the first and second temperature-measuring electrodes 11, 12. By detecting the magnitude of the reverse current change between the first and second temperature-measuring electrodes 11, 12, the VCSEL's own temperature can be measured. Furthermore, a degaussing coil electrode 10 is disposed outside the temperature-measuring electrodes and the switch electrode. Using the principle of electromagnetic induction, a current is passed through the degaussing coil electrode 10 to generate a magnetic field. This magnetic field is equal in magnitude and opposite in direction to the total magnetic field generated by the temperature-measuring electrodes and the switch electrode, thereby rendering the VCSEL as a whole non-magnetic. That is, the VCSEL in this application does not require additional components to achieve temperature measurement and demagnetization, which reduces production costs and improves production efficiency, while keeping its volume at the chip level, making it smaller than existing VCSELs.

[0074] Please refer to Figure 2 and Figure 3 Based on the above embodiment, in one embodiment of the present application, the vertical cavity surface emitting laser further includes:

[0075] an elliptical microlens 15 provided on the upper surface of the VCSEL epitaxial structure;

[0076] a dielectric film layer 16 disposed on the surface of the elliptical microlens 15;

[0077] Among them, the angles between the long axis of the elliptical microlens 15 and the

[110] and [-110] crystal directions are both 45°, and the elliptical microlens 15, the dielectric film layer 16 and the P-type DBR layer 5 in the VCSEL epitaxial structure together serve as the top reflector of the vertical cavity surface emitting laser.

[0078] Figure 3 The middle dashed line represents the major axis of the elliptical microlens 15 , and the shapes of the switch electrode, the temperature measuring electrode, and the degaussing coil electrode 10 are shown as rings.

[0079] The elliptical microlens 15 is prepared by etching the intrinsic GaAs layer in the P-type cap layer 6. The long axis length of the elliptical microlens 15 can be 3 microns to 10 microns, the radius of curvature in the long axis direction can be 50 microns to 1000 microns, the short axis length can be 1 micron to 5 microns, and the radius of curvature in the short axis direction can be 25 microns to 500 microns.

[0080] The dielectric film layer 16 can include alternating layers of silicon dioxide and silicon nitride. The thickness of the silicon dioxide and silicon nitride layers can be one-quarter optical thickness, ranging from 50 nanometers to 500 nanometers depending on the VCSEL operating wavelength. The number of dielectric film layers 16 can be 2 to 20, with a total thickness of 100 nanometers to 10 microns. It should be noted that the dielectric film layer can also be formed of other types of dielectric materials, such as magnesium fluoride, as long as the reflectivity is sufficient to allow the laser to oscillate between the top reflector formed by the dielectric film layer 16, the elliptical microlens 15, and the P-type DBR layer 5, and the bottom reflector N-type DBR layer 2.

[0081] In the existing vertical cavity surface emitting laser, the P-type DBR layer 5 serves as the top reflector and the N-type DBR layer 2 serves as the bottom reflector, so that the light emitted by the active layer 3 oscillates and amplifies between the two reflectors. More than 25 layers of P-type DBR layers 5 are required to provide sufficient reflectivity for the VCSEL to reach the lasing state. However, the light field inside the VCSEL is confined between the N-type DBR layer 2 and the P-type DBR layer 5, resulting in a short effective cavity length of the VCSEL. The laser linewidth output by the VCSEL is generally around 100 MHz. In this embodiment, the dielectric film layer 16, the elliptical microlens 15 and the P-type DBR layer 5 collectively serve as a top reflector, and the number of layers of the P-type DBR layer 5 is reduced. The number of film layers included in the P-type DBR layer 5 is less than 20 pairs (the number of film layers included in the P-type DBR layer 5 can be 10 to 15 pairs, and the thickness of the P-type DBR layer 5 can be 1 micron to 5 microns). The thickness of the P-type cap layer 6 is increased, and the elliptical microlens 15 is provided on the P-type cap layer 6. The dielectric film layer 16 is deposited on the surface of the elliptical microlens 15. This compensates for the problem of reduced reflectivity due to the decrease in the number of P-type DBR layers 5, expands the light field of the VCSEL beyond the P-type DBR layer 5, increases the effective cavity length, and can effectively narrow the laser linewidth of the VCSEL.

[0082] The laser light emitted by the VCSEL in the prior art is in a linearly polarized state. The polarization direction of the linearly polarized light is along one side of the square VCSEL chip, which is also the fixed crystal orientation of the crystal. This is called polarization along the

[110] crystal orientation or the [-110] crystal orientation, and the two directions are perpendicular to each other. The phase difference between the light in the

[110] crystal orientation and the [-110] crystal orientation is 0, so the output laser light is in a linearly polarized state. In the prior art, if you want to change the laser light emitted by the VCSEL from a linearly polarized state to a circularly polarized state, you need to use additional focusing lenses, polarizers, and other lens groups to achieve this, which increases the production cost and volume of the VCSEL. In this embodiment, by providing an elliptical microlens 15 and aligning its long axis with both the

[110] and [-110] crystal directions at 45°, the phase difference between the light in the

[110] and [-110] directions is no longer zero, resulting in circularly polarized laser light emitted by the vertical cavity surface emitting laser. Compared to existing technologies, this reduces manufacturing costs and size. Furthermore, the elliptical microlens 15 also provides a beam focusing effect, resulting in a smaller divergence angle for the emitted laser light than that of light emitted by VCSELs in existing technologies.

[0083] Based on any of the above embodiments, in one embodiment of the present application, please refer to Figure 4 and Figure 5 , vertical cavity surface emitting lasers also include:

[0084] The heating coil electrode 17 , which is disposed on the upper surface of the insulating layer 9 and located inside the degaussing coil electrode 10 , is used to generate heat by passing current to heat the vertical cavity surface emitting laser.

[0085] The heating coil electrode 17 can have a width of 10 to 100 microns, a thickness of 100 to 500 nanometers, and a number of turns of 2 to 20. The material can be an alloy of titanium, platinum, gold, nickel, germanium, or the like. The heating coil electrode 17 generates heating through Joule heating. The proportion of metal material in the heating coil electrode 17 differs from that in the other electrodes, and the resistance of the heating coil electrode 17 can range from 200 to 5000 ohms.

[0086] Current is passed through the heating coil electrode 17, and the Joule heating effect of the current enables the VCSEL to self-heat. Compared to the prior art method of soldering the VCSEL to a heating plate with a heating function to achieve chip heating, the VCSEL in this embodiment can self-heat, reducing heating production costs and keeping the VCSEL volume at the chip level. Furthermore, by designing the proportion of metal material in the heating coil electrode 17 and the size of the heating coil electrode 17, a heating coil electrode 17 with a fixed resistance value can be obtained. Heat can be controlled by controlling the current. Combined with the temperature measuring electrode, the temperature of the VCSEL itself can be controlled.

[0087] It can be understood that when current is passed through the heating coil electrode 17, a magnetic field will also be generated. In this embodiment, the magnetic field generated by the demagnetization coil electrode 10 is equal in magnitude and opposite in direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode and the heating coil electrode 17, so that the vertical cavity surface laser emitter as a whole is non-magnetic.

[0088] It should be noted that the shape of the heating coil electrode 17 is not limited in this application and can be customized. The shape of the heating coil electrode 17 can be annular or square, etc. The shape of the heating coil electrode 17 can be the same as or different from the shape of the switch electrode, temperature measuring electrode, and degaussing coil electrode 10, all within the scope of protection of this application. Figure 5 The shapes of the middle switch electrode, the temperature measuring electrode, the degaussing coil electrode 10 and the heating coil electrode 17 are all shown as rings.

[0089] This application also provides a method for manufacturing a vertical cavity surface emitting laser, please refer to Figure 6 , the method comprising:

[0090] Step S101: growing a VCSEL epitaxial structure on the upper surface of a substrate.

[0091] An N-type DBR layer, active layer, oxide layer, P-type DBR layer, and P-type cap layer are sequentially formed on a substrate through epitaxial growth to obtain a wafer containing a VCSEL epitaxial structure. The P-type cap layer comprises a doped GaAs layer and an intrinsic GaAs layer stacked from bottom to top.

[0092] It should be noted that before step S102 and after step S101, the following steps are also included:

[0093] Using a pre-designed first photolithography pattern for etching to form an isolation trench, a photolithography process is performed on the surface of the VCSEL epitaxial structure, and the isolation trench is formed by dry etching to obtain a wafer containing the isolation trench and the VCSEL epitaxial structure;

[0094] The oxide layer is partially oxidized by a wet oxidation process to form an oxide aperture, thereby obtaining a wafer containing an isolation trench and the oxide aperture.

[0095] Step S102: growing an insulating layer on the surface of the VCSEL epitaxial structure.

[0096] The PECVD (Plasma Enhanced Chemical Vapor Deposition) method is used to grow an insulating layer on the surface of the wafer including the isolation trench, oxidation aperture and VCSEL epitaxial structure; and with the help of a pre-designed second photolithography pattern for etching the insulating layer, a photolithography etching process is used to etch away part of the insulating layer.

[0097] A partial schematic diagram of the second photolithography layout for etching the insulating layer is shown in FIG. Figure 7 As shown, it includes a light-transmitting layer 102 and a light-impermeable layer 101 .

[0098] Step S103: growing a switch electrode, a temperature measuring electrode and a degaussing coil electrode to obtain a vertical cavity surface emitting laser;

[0099] The temperature measuring electrode is located outside the switch electrode, and includes a first temperature measuring electrode provided on the upper surface of the VCSEL epitaxial structure and a second temperature measuring electrode provided at the bottom of the isolation trench. The temperature measuring electrode is used to apply a voltage opposite to that of the switch electrode.

[0100] The degaussing coil electrode is located on the upper surface of the insulating layer; the degaussing coil electrode is located outside the temperature measuring electrode and is used to pass current to generate a magnetic field that is equal in magnitude and opposite in direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode and the vertical cavity surface emitting laser.

[0101] With the help of the pre-designed fourth photolithography pattern for preparing switch electrodes, temperature measuring electrodes and degaussing coil electrodes, the switch electrodes, temperature measuring electrodes and degaussing coil electrodes are grown on the surface of the wafer including the VCSEL epitaxial structure through a lift-off process.

[0102] It should be noted that after growing the switch electrodes, temperature measuring electrodes and degaussing coil electrodes, an annealing process is also performed to form ohmic contacts, and the wafer after the preparation process is completed is cleaved into vertical cavity surface emitting laser chips.

[0103] The vertical cavity surface emitting laser (VCSEL) fabricated using the method of this embodiment is provided with temperature-measuring electrodes. The temperature-measuring electrodes include a first temperature-measuring electrode disposed on the upper surface of the VCSEL epitaxial structure and a second temperature-measuring electrode disposed at the bottom of the isolation trench. A voltage opposite to that of the switch electrode is applied to the first and second temperature-measuring electrodes. Utilizing the PN junction characteristics of the VCSEL epitaxial structure, a semiconductor Peltier effect is generated between the first and second temperature-measuring electrodes. When the temperature within the VCSEL changes, corresponding current changes occur across the first and second temperature-measuring electrodes. By detecting the magnitude of the reverse current change between the first and second temperature-measuring electrodes, the VCSEL's own temperature can be tested. Furthermore, in this application, a degaussing coil electrode is disposed outside the temperature-measuring electrode and the switch electrode. Using the principle of electromagnetic induction, a current is passed through the degaussing coil electrode to generate a magnetic field. This magnetic field is equal in magnitude and opposite in direction to the total magnetic field generated by the temperature-measuring electrode and the switch electrode, thereby rendering the VCSEL as a whole non-magnetic. That is, the VCSEL in this application does not require additional components to achieve temperature measurement and demagnetization, which reduces production costs and improves production efficiency, while keeping its volume at the chip level, making it smaller than existing VCSELs.

[0104] On the basis of the above embodiment, in one embodiment of the present application, before growing the switch electrode, the temperature measuring electrode and the degaussing coil electrode, the following steps are further included:

[0105] preparing an elliptical microlens on the upper surface of the VCSEL epitaxial structure;

[0106] depositing a dielectric film layer on the surface of the elliptical microlens;

[0107] The angles between the major axis of the elliptical microlens and the

[110] and [-110] crystal directions are both 45°, and the elliptical microlens, the dielectric film layer and the P-type DBR layer in the VCSEL epitaxial structure together serve as the top reflector of the vertical cavity surface emitting laser.

[0108] With the help of the pre-designed third photolithography pattern for preparing elliptical microlenses, the elliptical microlenses are prepared by etching the intrinsic GaAs layer in the P-type cap layer on the wafer surface with part of the insulating layer etched away.

[0109] A dielectric film layer is deposited on the surface of the elliptical microlens, and the dielectric film layer on the wafer surface except for the portion covering the elliptical microlens is removed using a third photolithography pattern and a negative resist photolithography process.

[0110] In this embodiment, by preparing an elliptical microlens and a dielectric film layer, the laser emitted by the vertical cavity surface emitting laser is circularly polarized light. The elliptical microlens also has a beam focusing effect, making the divergence angle of the emitted laser smaller than the divergence angle of the light emitted by the VCSEL in the prior art. The dielectric film layer, the elliptical microlens and the P-type DBR layer together serve as a top reflector, so that the light field of the VCSEL extends beyond the P-type DBR layer, thereby increasing the effective cavity length and effectively narrowing the laser linewidth of the VCSEL.

[0111] On the basis of any of the above embodiments, in one embodiment of the present application, the method for manufacturing a vertical cavity surface emitting laser further includes:

[0112] A heating coil electrode is grown on the upper surface of the insulating layer; the heating coil electrode is located inside the degaussing coil electrode and is used to pass current to generate heat to heat the vertical cavity surface emitting laser.

[0113] With the help of the pre-designed fifth photolithography pattern for preparing the heating coil electrode, the heating coil electrode is grown on the surface of the wafer using a lift-off process.

[0114] In this embodiment, a heating coil electrode is prepared and self-heating of the VCSEL is achieved through the Joule heating effect of the current. By designing the proportion of metal materials in the heating coil electrode and the size of the heating coil electrode, a heating coil electrode with a fixed resistance value can be obtained. Heat control can be achieved by controlling the current size. Combined with the temperature measuring electrode, the temperature control of the VCSEL itself can be achieved.

[0115] Taking a vertical cavity surface emitting laser including an elliptical microlens, a dielectric film layer, a temperature measuring electrode, a heating coil electrode and a degaussing coil electrode as an example, the manufacturing method of the vertical cavity surface emitting laser in this application is explained.

[0116] Step 1: Take an N-type GaAs substrate and sequentially prepare an N-type DBR layer, an active layer, an oxide layer, a P-type DBR layer, and a P-type cap layer by epitaxial growth to obtain a wafer containing an epitaxial structure.

[0117] Step 2: Perform a photolithography process on the wafer surface using the first photolithography pattern in step 1, and a dry etching process to prepare isolation trenches to obtain a wafer containing isolation trenches.

[0118] Step 3: Using a wet oxidation process, partially oxidize the oxide layer of the wafer having the isolation trench to prepare an oxide aperture, thereby obtaining a wafer containing the isolation trench and the oxide aperture.

[0119] Step 4: Using PECVD equipment to grow an insulating layer on the surface of the wafer containing the isolation trench and the oxidation aperture.

[0120] Step 5: Use a second photolithography pattern on the surface of the wafer on which the insulating layer is grown, and etch away part of the insulating layer through a photolithography and etching process.

[0121] Step 6: Using the third photolithography pattern, prepare an elliptical microlens on the wafer surface where part of the insulating layer has been etched away.

[0122] Step 7: depositing a dielectric film layer on the surface of the elliptical microlens, and removing the dielectric film layer on the wafer surface except for the portion covering the microlens using a third photolithography pattern and a negative resist photolithography process.

[0123] Step 8: Using the fourth photolithography pattern and lift-off process, switch electrodes, temperature measuring electrodes and degaussing coil electrodes are grown on the surface of the wafer.

[0124] Step 9: Use a photolithography pattern-free and lift-off process to grow heating coil electrodes on the wafer surface.

[0125] Step 10: Perform an annealing process on the wafer to form an ohmic contact.

[0126] Step 11: Cleave the wafer after the preparation process into chips to obtain a vertical cavity surface emitting laser.

[0127] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0128] The above is a detailed introduction to the vertical cavity surface emitting laser and its manufacturing method provided by this application. This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the scope of protection of the claims of this application.

Claims

1. A vertical cavity surface emitting laser, characterized in that: include: substrate; a VCSEL epitaxial structure provided on the upper surface of the substrate; an insulating layer provided on the upper surface of the VCSEL epitaxial structure; A temperature measuring electrode provided outside the switch electrode, for applying a voltage opposite to that of the switch electrode; the temperature measuring electrode comprises a first temperature measuring electrode provided on the upper surface of the VCSEL epitaxial structure, and a second temperature measuring electrode provided at the bottom of the isolation trench; The degaussing coil electrode is provided on the upper surface of the insulating layer and outside the temperature measuring electrode, and is used to pass current to generate a magnetic field that is equal in magnitude and opposite in direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode and the vertical cavity surface emitting laser.

2. The vertical cavity surface emitting laser according to claim 1, wherein Also includes: an elliptical microlens provided on the upper surface of the VCSEL epitaxial structure; a dielectric film layer provided on the surface of the elliptical microlens; The angles between the major axis of the elliptical microlens and the [110] and [-110] crystal directions are both 45°, and the elliptical microlens, the dielectric film layer and the P-type DBR layer in the VCSEL epitaxial structure together serve as the top reflector of the vertical cavity surface emitting laser.

3. The vertical cavity surface emitting laser according to claim 2, wherein: The number of film layers included in the P-type DBR layer is less than 20 pairs.

4. The vertical cavity surface emitting laser according to claim 2, wherein: The dielectric film layer includes alternately stacked silicon dioxide layers and silicon nitride layers.

5. The vertical cavity surface emitting laser according to claim 1, wherein: Also includes: The heating coil electrode is provided on the upper surface of the insulating layer and located inside the degaussing coil electrode, and is used for passing current to generate heat so as to heat the vertical cavity surface emitting laser.

6. The vertical cavity surface emitting laser according to claim 1, wherein: The P-type cap layer in the VCSEL epitaxial structure includes a doped GaAs layer and an intrinsic GaAs layer stacked from bottom to top, wherein the thickness of the intrinsic GaAs layer is three quarters of the optical thickness, which is the product of the operating wavelength and the refractive index.

7. The vertical cavity surface emitting laser according to any one of claims 1 to 6, wherein: The switch electrode, the temperature measuring electrode and the degaussing coil electrode are all ring-shaped.

8. A method for manufacturing a vertical cavity surface emitting laser, characterized in that: include: Growing a VCSEL epitaxial structure on the upper surface of the substrate; Growing an insulating layer on the upper surface of the VCSEL epitaxial structure; growing switch electrodes, temperature measuring electrodes and degaussing coil electrodes to obtain a vertical cavity surface emitting laser; The temperature measuring electrode is located outside the switch electrode, and includes a first temperature measuring electrode provided on the upper surface of the VCSEL epitaxial structure and a second temperature measuring electrode provided at the bottom of the isolation trench. The temperature measuring electrode is used to apply a voltage opposite to that of the switch electrode. The degaussing coil electrode is located on the upper surface of the insulating layer; the degaussing coil electrode is located outside the temperature measuring electrode and is used to pass current to generate a magnetic field that is equal in magnitude and opposite in direction to the total magnetic field generated by the switch electrode, the temperature measuring electrode and the vertical cavity surface emitting laser.

9. The method for manufacturing a vertical cavity surface emitting laser according to claim 8, wherein: Before growing the switch electrode, temperature measuring electrode and degaussing coil electrode, it also includes: preparing an elliptical microlens on the upper surface of the VCSEL epitaxial structure; depositing a dielectric film layer on the surface of the elliptical microlens; The angles between the major axis of the elliptical microlens and the [110] and [-110] crystal directions are both 45°, and the elliptical microlens, the dielectric film layer and the P-type DBR layer in the VCSEL epitaxial structure together serve as the top reflector of the vertical cavity surface emitting laser.

10. The method for manufacturing a vertical cavity surface emitting laser according to claim 8 or 9, wherein: Also includes: A heating coil electrode is grown on the upper surface of the insulating layer; the heating coil electrode is located inside the degaussing coil electrode and is used to pass current to generate heat to heat the vertical cavity surface emitting laser.

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