CN112993748B - Vertical cavity surface emitting laser based on liquid crystal regulation and control and preparation method thereof - Google Patents

Abstract

The invention provides a vertical cavity surface emitting laser based on liquid crystal regulation, which comprises a traditional oxidation limiting type vertical cavity surface emitting laser structure and a liquid crystal mode modulation structure, wherein the traditional oxidation limiting type vertical cavity surface emitting laser structure is used for emitting an excitation mode; and the liquid crystal mode modulation structure is positioned on the traditional oxidation limiting type vertical cavity surface emitting laser structure, and realizes the influence on the loss of a transmission light field through the change of the refractive index of liquid crystal so as to control a lasing mode. The invention also provides a preparation method for preparing the vertical cavity surface emitting laser based on liquid crystal regulation.

Description

Vertical cavity surface emitting laser based on liquid crystal regulation and control and preparation method thereof

Technical Field

The invention relates to the technical field of semiconductor laser devices, in particular to a vertical cavity surface emitting laser based on liquid crystal regulation and control and a preparation method thereof, which are used for realizing high-order mode suppression.

Background

The development of Vertical Cavity Surface Emitting Lasers (VCSELs) generally began with the concept first proposed by the Iga research group in 1977 to design an InP-based p-n junction Surface Emitting Laser. In the development of more than forty years, the structural framework of the VCSEL is gradually improved, including a Distributed Bragg Reflector (DBR) structure forming a highly reflective resonant cavity and an oxide aperture structure realizing current and optical field mode confinement, and meanwhile, the VCSEL has diversity, such as a High Contrast Grating (HCG) structure and a proton-injection aperture structure. On the other hand, the VCSEL has a huge application potential in various related fields due to its unique laser characteristics, from optical communication networks (including 850 nm-1060 nm wavelength band for short-distance optical communication and 1310 nm-1550 nm wavelength band for long-distance communication), to position and distance sensing (near infrared wavelength band mainly including 940 nm), and is currently very diverse in consumer electronics market, and has a huge market potential in the laser radar unmanned field.

Depending on the needs of different fields, the study of VCSEL laser characteristics to achieve different transverse mode outputs, including single mode and few modes, with output powers of milliwatts or higher, is necessary. Although various methods have been proposed for implementing single-mode VCSELs, such as antiresonant reflecting optical waveguide (ARROWs) design, porous structure design, photonic crystal structure, etched surface relief, etc., these designs have the disadvantages of requiring complicated epitaxial growth and structure etching and having extremely high precision requirements, and the output mode is fixed and cannot be adjusted after being manufactured, so that further optimization and improvement are still needed in practical application.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a vertical cavity surface emitting laser based on liquid crystal modulation and a method for manufacturing the same, so as to partially solve at least one of the above technical problems.

To achieve the above objects, as one aspect of the present invention, there is provided a vertical cavity surface emitting laser based on liquid crystal regulation, including a conventional oxidized confined vertical cavity surface emitting laser structure and a liquid crystal mode modulation structure, wherein,

a conventional oxide confined vertical cavity surface emitting laser structure for emitting an excitation mode;

and the liquid crystal mode modulation structure is positioned on the traditional oxidation limiting type vertical cavity surface emitting laser structure, and realizes the influence on the loss of a transmission light field through the change of the refractive index of liquid crystal so as to control a lasing mode.

Wherein, the traditional oxidation limiting type vertical cavity surface emitting laser structure comprises from bottom to top:

the light-emitting diode comprises an N-type metal electrode layer, an N-type DBR layer, an active region, an oxide aperture layer, a P-type DBR layer and a P-type metal electrode layer; wherein, the active region is three InGaAs or AlGaAs quantum wells.

Wherein the liquid crystal mode modulation structure comprises:

a central column structure and an annular column groove structure formed by silicon dioxide, wherein the central column structure is used for promoting the lasing of the excitation light of the fundamental mode through phase matching, and the annular column groove structure is used for forming a liquid crystal box to fill liquid crystal;

and the liquid crystal layer is formed by filling the silicon dioxide grooves with liquid crystal materials.

The diameter of the central column structure is 3-5 microns, the outer diameter of the annular cylindrical groove structure is 20-25 microns, and the depth of the annular cylindrical groove structure is 3.5-3.6 microns.

Wherein the liquid crystal material is E7 type liquid crystal material.

Wherein the liquid crystal mode modulation structure further comprises:

a first ITO electrode layer and a top second ITO electrode layer grown on the thin glass sheet; the first ITO electrode layer is in contact with the P-type metal electrode layer.

Wherein the thickness of the first ITO electrode layer and the top second ITO electrode layer grown on the thin glass sheet is 130-135 nanometers.

The first ITO electrode layer and the top second ITO electrode layer growing on the thin glass sheet are located on the upper side and the lower side of the liquid crystal material and serve as liquid crystal electrodes to form capacitance electrodes, and the capacitance electrodes provide an external electric field for liquid crystals after the power supply is switched on to control the directional deflection of liquid crystal molecules.

The first ITO electrode layer and the top second ITO electrode layer growing on the thin glass sheet need to be subjected to orientation treatment, so that the liquid crystal material molecules can be ensured to be directionally deflected under the change of an applied electric field.

As another aspect of the present invention, there is provided a method for manufacturing the above vertical cavity surface emitting laser based on liquid crystal modulation, comprising the steps of:

implementing the traditional oxidation-limited vertical cavity surface emitting laser process, including silicon dioxide growth, photoetching development, wet etching, ICP etching, wet oxidation and the like;

growing an ITO layer on the surface of the oxidized confined vertical cavity surface emitting laser which finishes the traditional process;

growing a silicon dioxide layer on the grown ITO layer at 85 ℃, and forming an annular groove structure through photoetching and RIE etching;

and E7 type liquid crystal material is injected into the annular groove, and the annular groove is covered by an oriented ITO-coated thin glass sheet to form a liquid crystal box, so that the preparation of the vertical cavity surface emitting laser based on liquid crystal regulation is completed.

Based on the above technical solution, the vertical cavity surface emitting laser modulated by liquid crystal and the method for manufacturing the same of the present invention have at least one or a part of the following advantages compared with the prior art:

(1) The output mode of the laser, namely single mode or multimode, can be dynamically regulated according to the working state and application requirements of the laser;

(2) The threshold current of each output mode of the laser can be dynamically regulated and controlled according to the working state and application requirements of the laser;

(3) As the birefringence characteristic of the liquid crystal is closely related to the polarization characteristic of the transmission mode, the regulated high-order mode can be ensured to have single polarization characteristic.

Drawings

FIG. 1 is a schematic structural diagram of a vertical cavity surface emitting laser based on liquid crystal modulation according to an embodiment of the present invention;

FIG. 2 is a graph of refractive index as a function of voltage for the x and y polarization modes for an E7 mode liquid crystal material according to an embodiment of the present invention;

FIG. 3 shows the fluctuation of the transmission mode gain in the silica pillar structure, the x-polarization mode gain in the liquid crystal, and the difference between them with the thickness of the silica layer according to the embodiment of the present invention;

FIG. 4 (a) is a graph of the power-current curves for the four lasing modes LP01, LP11, LP21, LP02, according to an embodiment of the present invention, with the inset showing the normalized intensity distribution of the four modes on the surface; (b) - (d) is the laser spectrum for the modes at the 2mA, 6mA and 10mA injection currents, respectively;

FIG. 5 (a) is a graph showing the overlapping proportion coefficient of the central silica column and the four lasing modes in the embodiment of the present invention, and the change curve of the overlapping proportion of each mode is calculated according to the formula (3); (b) The difference curve of the overlapping proportion of the high-order mode and the basic mode; (c) The power-current curve of the structure without liquid crystal electro-tuning is obtained when the radius of the silicon dioxide column is set to be 2um, wherein the lasing power of the LP11, LP21 and LP02 modes in the displayed current range is almost kept to be 0; (d) And (e) laser spectra of the two cavities corresponding to 8mA and 11mA injection currents, respectively;

FIG. 6 (a) is a graph of threshold mode gain for a polarization-poor mode as a function of thickness and refractive index for a polarization-poor mode liquid crystal modulation structure calculated in an embodiment of the present invention; (b) - (f) is the threshold mode gain as a function of the electrically tuned refractive index for both polarizations in the liquid crystal (x-polarization marked as dark dashed line and y-polarization marked as light dashed line) and modes in the silicon dioxide (solid line) when the thickness of the silicon dioxide (or liquid crystal) layer is different, the spherical mark representing the dominant polarization mode in the competition of x-and y-polarization modes;

fig. 7 is a graph showing the change in threshold current of each lasing transverse mode with the change in the y-polarization mode refractive index of the liquid crystal when the thickness of the silicon dioxide layer (also the liquid crystal modulation layer) is set to 3.58 um. ( Dark shaded areas-single mode; neutral color shaded areas-two modes; light shaded area-three modes )

In the above drawings, the reference numerals have the following meanings:

1N type metal electrode

2N type DBR layer

3. Active region

4. Oxide pore size layer

5P type DBR layer

6P type metal electrode

7. Silicon dioxide layer

8 ITO electrode

9. Filled liquid crystal

Detailed Description

In order to solve the technical problems of flexible regulation and control of a VCSEL transverse lasing mode and the like in the prior art, the invention provides a mode-adjustable vertical cavity surface emitting laser based on liquid crystal and a preparation method thereof, wherein the mode of output can be dynamically regulated and controlled according to the working state and the requirement of the laser, meanwhile, the precision of a surface phase-inversion structure is not highly depended, the adjustable and controllable range is certain, and the related defects and shortcomings of the conventional vertical cavity surface emitting laser can be overcome.

The invention relates to a vertical cavity surface emitting laser based on liquid crystal regulation. Specifically, the laser structure of the present invention can be divided into two parts, one part is a conventional oxide confined vertical cavity surface emitting laser structure, and the other part is a liquid crystal mode modulation structure. The conventional oxide-confined VCSEL structure is used for emitting an excited mode, and the radius of the oxide aperture is 4 microns, so that the number and the type of the excitable modes are determined, and the conventional oxide-confined VCSEL structure is also an object to be modulated. The specific layer structure comprises an N-type metal electrode layer, an N-type DBR layer, an active region, an oxide aperture layer, a P-type DBR layer and a P-type metal electrode layer. Three indium gallium arsenic/aluminum gallium arsenic quantum wells are arranged in the active region, under the excitation of a voltage pumping source, particle number reversal is formed in the quantum wells, a large number of photons are released, light amplification is obtained through the action of the upper reflector, the lower reflector and the resonant cavity, and therefore laser emission is achieved. The liquid crystal mode modulation structure is a core structure with function control, is positioned on the traditional oxidation-limited vertical cavity surface emitting laser structure, and mainly realizes the influence on the transmission light field loss through the change of the refractive index of liquid crystal so as to control the lasing mode. The layer structure comprises a first ITO electrode layer, a silicon dioxide ring-shaped groove structure and a top second ITO electrode layer grown on a thin glass sheet. The first ITO electrode layer is in contact with the P-type metal electrode layer, the center of the annular groove structure is a silicon dioxide column, E7-type liquid crystal materials are filled in the annular groove to form a liquid crystal box, the upper contact layer and the lower contact layer of the liquid crystal box are the first ITO layer and the second ITO layer to form a capacitance electrode, and the capacitance electrode provides an external electric field for liquid crystal after a power supply is switched on and controls the directional deflection of liquid crystal molecules.

For the liquid crystal annular groove described above, its depth determines the anti-phase behavior of the standing wave inside the laser, which also affects the reflectivity of the top DBR. In the conventional research, the liquid crystal cell is not designed, so that the process needs extremely high precision, which is a difficult problem in process control, and on the other hand, the surface structure is easily partially corroded in the process of the process, so that the original size is damaged, and the overall reflectivity is influenced. In the invention, the liquid crystal material is introduced to control the refractive index of the liquid crystal layer part, so that the electrical control of the transmission loss of the liquid crystal groove part in the optical field mode is ensured, and the real-time control function of the lasing mode is realized.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings in combination with the embodiments.

In the embodiment of the present invention, as shown in fig. 1, the vertical cavity surface emitting laser based on liquid crystal modulation of the present invention can be seen by being divided into two parts: the lower half part is an oxidation-limited VCSEL structure, which comprises: 1-N type metal electrode, 2-N type DBR (substrate is omitted here, and actual bottom electrode should contact on the substrate), 3-active region containing 3 pairs of quantum well, 4-oxidation aperture layer, 5-P type DBR layer and 6-P type metal electrode, wherein the center of the oxidation aperture layer is oxidation hole; the upper half part is a liquid crystal modulation structure, comprising: the liquid crystal display comprises a first ITO electrode layer, a 7-silicon dioxide annular structure layer, a 8-second ITO electrode layer and a 9-liquid crystal layer, wherein the liquid crystal layer is a liquid crystal box structure which is filled in the silicon dioxide annular groove and is formed by closing an upper ITO layer and a lower ITO layer, the upper ITO layer and the lower ITO layer are used as electric field electrodes for controlling the adjustment of the refractive index of liquid crystal, the first ITO electrode layer is in contact with a P-type metal electrode layer, and a three-electrode device is formed integrally. By modulating the refractive index of the liquid crystal material, the reflectivity of the grooved part and the non-grooved part to the resonance wavelength can be accurately controlled, so that the round-trip loss of different transverse modes can be controlled.

In the embodiment of the invention, the reflectivity of the P-type DBR is designed to be about 99.2 percent, so that the liquid crystal modulation structure can exert enough influence on the liquid crystal modulation structure, the adjustable range of the whole reflectivity is larger, and a lower value can be reached, thereby inhibiting mode output. The first ITO layer grows on the traditional oxidation-limited VCSEL and is connected with the P-type metal electrode, the thickness of the ITO layer is 130-135 nanometers, and the design of the thickness value is related to a quarter of optical wavelength.

In the embodiment of the invention, a tunable electric field can be provided to induce the oriented deflection of the liquid crystal molecules on the xOz plane through the upper and lower ITO electrodes of the liquid crystal. The rotation angle of the liquid crystal molecules is defined as θ (as shown in the inset of FIG. 1), and can be adjusted by an applied tuning voltage V _t And (4) quantitative control. For E7-type nematic liquid crystals, the refractive index is anisotropic and depends on the direction of deflection of the liquid crystal molecules, which also affects the polarization of light along the direction of the crystal axis. The refractive index component along the long axis of the liquid crystal molecules and parallel to the long axis is the refractive index of extraordinary rays (n) _e ) And the refractive index component in the short axis direction is the ordinary refractive index (n) _o ). When a beam of light is transmitted along the Oz axis, the two orthogonally polarized refractive index components can be calculated by the following equation:

n _x ＝n _o ，

the refractive index (@ 940 nm) of nematic liquid crystals can be measured experimentally according to the principle of polarized light interference. For the E7 type nematic liquid crystal, the birefringence index value is the refractive index n of ordinary rays in the wavelength range of the invention _o Index of refraction n of extraordinary ray =1.5 _e =1.7. In addition, a tuning voltage V is applied to the liquid crystal _t When the refractive index changes in the longitudinal direction for the x-polarization mode and the y-polarization mode are different, as shown in fig. 2. It can be seen that the refractive index of the x-polarization mode remains constant at all times, while the refractive index of the y-polarization mode will vary with the tuning voltage V _t From n to n _o Increase to n _e This is also caused by the rotation of the liquid crystal molecules.

In embodiments of the present invention, first, a suitable thickness of the silicon dioxide layer or liquid crystal layer and a suitable central silicon dioxide column radius need to be considered. Using a one-dimensional plane wave transmission matrix method, the reflectivity of the top DBR at different thicknesses of the silicon dioxide layer (refractive index n = 1.44) can be calculated, and then the threshold modal gain (TMG = r × gth) can also be obtained according to the following equation and plotted as a graph (shown in fig. 3):

wherein gamma is a longitudinal restriction factor, g _th Is the threshold material gain, alpha _i Is the inherent internal loss, L is the effective optical resonator length, R _b Is the reflectivity of the bottom DBR, which is close to 1,R _t Is the reflectivity of the top DBR, whose value fluctuates periodically with increasing thickness of the silicon dioxide layer, the corresponding threshold mode gain also fluctuates periodically, as shown by the curve in fig. 3. To facilitate fundamental mode lasing while suppressing higher order modes, we need to ensure that the loss of the central silica part is lower, while the x-polarization mode loss of the surrounding liquid crystal part is higher, corresponding to the former being lower TMG and the latter being higher. In FIG. 3, the difference between the two TMGs is also shown by the black curve, the middle red dotted line indicates its optimum value (thickness of 3.58 microns), so we preset the thickness of the central silica column to be 3.58 microns. At this thickness, the threshold mode gain of the silicon dioxide portion is the smallest and the threshold mode gain of the liquid crystal portion in the x-polarization mode is the largest.

On the other hand, whether the transverse modes can lase depends to a large extent on their respective mode losses. To ensure a large difference in threshold mode gain between the fundamental and higher modes, it is also important to find a suitable central silica pillar radius, and therefore further we need to consider the lateral mode distribution of the oxide-confined VCSEL. For the oxidized confinement type VCSEL, the oxidized confinement type VCSEL can be approximately equivalent to a weak optical fiber waveguide, and the transverse mode distribution of the oxidized confinement type VCSEL can be calculated according to the correlation theory of an optical fiber waveguide model. In the embodiment of the present invention, the radius of the oxide aperture is 4 μm, and the supportable transverse moduli of the VCSEL are 4, which are LP01, LP11, LP02 and LP21, respectively, we design a device with the same VCSEL structure but without the liquid crystal modulation structure as a reference, and simulate and plot the power-current (L-I) curves of all lasing transverse modes, as shown in fig. 4 (a). To show more clearly the lasing at different currents, fig. 4 (b) - (d) are the lasing spectra at the corresponding three currents (2 mA, 6mA and 10 mA). The inset in figure 4 (a) shows the normalized intensity distribution of the four laser modes on the VCSEL light emitting surface from which we can see where each mode's optical field is concentrated, but the most appropriate radius cannot be directly determined from their field distribution alone.

In order to qualitatively analyze the lateral mode filtering situation under different silica column radiuses, a parameter, namely an overlapping factor (F) is introduced _f ) The ratio of the overlap of the columnar structure with each transverse mode is determined by a method similar to the transverse confinement factor of a conventional oxide-confined VCSEL, as shown in the following formula:

wherein the field intensity distribution E of each transverse mode _mn Can be extracted from the inset of fig. 4 (a). The overlap scaling factor for each transverse mode has been calculated according to the above equation and is shown in fig. 5 (a). From the curves in the figure we can assume the radius r of the central column _f Starting from 0, the mode with the most rapidly growing overlapped part at this time is LP02, so that the LP02 mode becomes the biggest threat of fundamental mode lasing at this time because the overlapping proportion of other modes is too small to reach the lasing condition. As the radius rf continues to increase, the overlap ratio of the fundamental mode LP01 has grown faster and faster, which in turn makes the LP02 mode much less competitive. On the other hand, we need to ensure that higher order modes are suppressed as much as possible. Therefore, we find the difference r in the overlap ratio between the higher-order mode and the fundamental mode _f Reaches a maximum around 2um as shown in fig. 5 (b). Further, we have simulated the overall structure without liquid crystal modulation under the above parameters and plotted its power-current curve in fig. 5 (c), and we can see that this structure remains in the singlet mode lasing state throughout the entire current range shown. FIGS. 5 (d) and (e) are also divided intoShows the lasing spectra at injection currents of 8mA and 11mA, respectively, including a central cavity (radius r) _f A central silicon dioxide column portion) and a surrounding cavity (a liquid crystal portion around the silicon dioxide column). In fact, if one were to guarantee that thermal rollover is not reached with further increase in injection current, there would be a higher order mode that would occur because the overall gain would be greater.

In the embodiment of the present invention, in order to demonstrate the mode control and real-time adjustment effects of the liquid crystal structure, we first calculate the threshold mode gain TMG under the conditions of different modulation layer thicknesses and different y polarization mode liquid crystal refractive indexes, and the result is plotted in fig. 6 (a), and we can see that the TMG can be adjusted by electrical modulation of the liquid crystal refractive index under different thicknesses from 3.53um to 3.63 um. Clearer results have been shown in fig. 6 (b) - (f), where the solid line represents the threshold mode gain of the transverse mode transmitted in the central column cavity at the current thickness; the dark and light dashed lines represent the threshold mode gains for x-polarization and y-polarization modes, respectively, propagating within the surrounding liquid crystal cavity at the current thickness, where the threshold mode gain for the y-polarization mode fluctuates with electrical tuning of the liquid crystal refractive index. It is this TMG differential change that causes competition between the x and y polarization modes, where the dominant polarization mode is marked by a sphere of the corresponding chromaticity. As shown in fig. 6 (c), (d), and (e), when the thickness of the silica layer is in the range of 3.555 to 3.605 μm, the x-polarization mode in the liquid crystal is not excited because the x-polarization mode has a larger threshold mode gain than the y-polarization mode almost in the entire adjustable refractive index range of the liquid crystal. On the other hand, as the threshold mode gain of the y-polarization modes decreases, these modes may lase over this limited current range, as shown more clearly in fig. 7. Further, the case shown in fig. 6 (b) and (f) is a critical thickness at which the x-polarization mode in the liquid crystal can lase as a dominant mode at a large injection current (around 12 mA) because its threshold mode gain is no longer large enough to be suppressed (this conclusion can be drawn by comparing fig. 6 (d) and fig. 7). From the discussion we can conclude that full mode control can be achieved by adjusting the liquid crystal refractive index in the range of 100 nm for liquid crystal modulation layer thicknesses from 3.53 microns to 3.63 microns, and that this thickness error is fully controllable in PECVD growth. It is worth mentioning that the polarization of the higher order modes of lasing can remain almost unchanged throughout the tuning process.

In another embodiment of the present invention, based on the above analysis, we performed a series of simulations using Crosslight Pics3D software, which shows the effect of mode control. In these simulations, the refractive index of the liquid crystal structure was set directly to a value of 1.5 to 1.7. For example, the thickness of the silicon dioxide layer (i.e., the liquid crystal layer) of the modulation structure is set to 3.58 μm, and the radius of the central silicon dioxide column is r _f =2 microns, the higher order modes can be precisely controlled as the refractive index changes, and we have demonstrated the transverse mode and threshold current of lasing under this modulation condition in fig. 7. Wherein, the dark shaded area represents the working state that only the basic mode (LP 01) is shot; the medium chroma shaded region indicates that the second mode (LP 11) can lase, while the subsequent mode cannot, i.e. there are two lasing modes; the lightly shaded areas indicate that the third mode (LP 21) can also lase. Here we need to clarify that we only consider the range of injection currents from 0mA to 12mA, ignoring the modes that might lase at higher currents. In the case of an expanded injection current range, the lasing lateral mode is still controllable due to the large difference in threshold current for each mode.

In order to realize the manufacturing of the emitting laser, the invention also provides a preparation method of the vertical cavity surface emitting laser based on liquid crystal regulation, which mainly comprises the following operations:

the process S1: the traditional oxidation-limited vertical cavity surface emitting laser process comprises silicon dioxide growth, photoetching development, wet etching, ICP etching, wet oxidation and the like.

The process S2: growing an ITO layer on the surface of the oxidized confined vertical cavity surface emitting laser which finishes the traditional process;

the process S3: growing a silicon dioxide layer on the ITO grown in the process S1 at 85 ℃, and forming the annular groove structure through photoetching and RIE etching;

the process S4: and E7 type liquid crystal material is injected into the annular groove and is covered by an oriented ITO-coated thin glass sheet to form a liquid crystal box, and the preparation of the vertical cavity surface emitting laser based on liquid crystal regulation is finished.

In summary, the invention provides a vertical cavity surface emitting laser based on liquid crystal regulation and control and a preparation method thereof, relates to the technical field of semiconductor lasers, and designs a VCSEL laser structure based on liquid crystal to accurately regulate and control high and low transverse modes in real time. The design comprises a VCSEL basic epitaxial structure and a micro-regulation layer for realizing the regulation function of a high-low order mode. The basic epitaxial structure is a plurality of pairs of upper and lower DBR layers, a multi-quantum well active region sandwiched between the upper and lower DBR layers and a covering protective layer on the surface of an epitaxial wafer; the micro-control layer for realizing the function comprises an ITO layer for forming a transparent electrode and a high-order mode suppression unit structure formed by combining a liquid crystal material and silicon dioxide. Through reasonable unit structure parameter design and the refractive index adjustability of the liquid crystal material, the micro-regulation layer can achieve the function of accurately controlling the high-order mode loss under the condition of low requirements on process conditions, namely, the micro-regulation layer is used for accurately regulating the phase matching condition of standing waves formed by light oscillation inside a laser, so that the high-order mode is inhibited due to phase inversion, and excellent laser characteristics are finally realized. The realization of the function of the device has great practical value in our production and life.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. A vertical cavity surface emitting laser based on liquid crystal regulation, characterized in that the vertical cavity surface emitting laser comprises a conventional oxide confined vertical cavity surface emitting laser structure and a liquid crystal mode modulation structure, wherein,

a conventional oxide confined vertical cavity surface emitting laser structure for emitting an excitation mode;

the liquid crystal mode modulation structure is positioned on the traditional oxidation-limited vertical cavity surface emitting laser structure, and the influence on the loss of a transmission light field is realized through the change of the refractive index of liquid crystal, so that a lasing mode is controlled;

wherein the liquid crystal mode modulation structure comprises:

a central column structure and an annular column groove structure formed by silicon dioxide, wherein the central column structure is used for promoting the lasing of the excitation light of the fundamental mode through phase matching, and the annular column groove structure is used for forming a liquid crystal box to fill liquid crystal;

and the liquid crystal layer is formed by filling the silicon dioxide grooves with liquid crystal materials.

2. The VCSEL of claim 1, wherein the conventional oxidized confined VCSEL structure includes, from bottom to top:

the N-type metal electrode layer, the N-type DBR layer, the active region, the oxide aperture layer, the P-type DBR layer and the P-type metal electrode layer; wherein, the active region is three InGaAs or AlGaAs quantum wells.

3. The VCSEL of claim 1, wherein the center post structure diameter is 3-5 microns, the outer diameter of the ring post groove structure is 20-25 microns, and the depth of the ring post groove structure is 3.5-3.6 microns.

4. A vcsel according to claim 1, wherein said lc material is selected from the group consisting of E7 mode lc materials.

5. A vertical cavity surface emitting laser according to claim 1, wherein said liquid crystal mode modulation structure further comprises:

a first ITO electrode layer and a top second ITO electrode layer grown on the thin glass sheet; the first ITO electrode layer is in contact with the P-type metal electrode layer.

6. A vertical cavity surface emitting laser according to claim 5, wherein said first ITO electrode layer and top second ITO electrode layer grown on the thin glass sheet are 130-135 nm thick.

7. A vertical cavity surface emitting laser according to claim 5, wherein said first ITO electrode layer and top second ITO electrode layer grown on the thin glass sheet are located on both upper and lower sides of the liquid crystal material as liquid crystal electrodes to form capacitance electrodes, said capacitance electrodes providing an external electric field for the liquid crystal after power-on to control the directional deflection of the liquid crystal molecules.

8. The VCSEL of claim 5, wherein the first ITO electrode layer and a top second ITO electrode layer grown on a thin glass sheet need to be subjected to an alignment process to ensure that the liquid crystal material molecules are directionally deflected by a change in an applied electric field.

9. A method for preparing a vertical cavity surface emitting laser based on liquid crystal modulation, which is used for preparing the vertical cavity surface emitting laser based on liquid crystal modulation according to any one of claims 1 to 8, and comprises the following steps:

the process for preparing the oxidation-limited vertical cavity surface emitting laser comprises the steps of silicon dioxide growth, photoetching development, wet etching, ICP etching and wet oxidation;

growing an ITO layer on the surface of the prepared oxidation-limited vertical cavity surface emitting laser;

growing a silicon dioxide layer on the grown ITO layer at 85 ℃, and forming an annular groove structure through photoetching and RIE etching;

and E7 type liquid crystal material is injected into the annular groove, and the annular groove is covered by an oriented ITO-coated thin glass sheet to form a liquid crystal box, so that the preparation of the vertical cavity surface emitting laser based on liquid crystal regulation is completed.

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