Optical pumping organic laser with dual-wavelength composite resonance and preparation method thereof

Abstract

The invention belongs to the field of lasers, and particularly relates to a dual-wavelength composite resonance optical pumping organic laser and a preparation method thereof.The laser comprises a bottom Bragg reflector, a grating layer, an active layer, a medium compensation layer and a top Bragg reflector which are sequentially arranged from bottom to top; the bottom Bragg reflector, the grating layer, the active layer, the medium compensation layer and the top Bragg reflector form a vertical resonant cavity. On the basis of a conventional DFB laser structure, the DBR structure is added in the vertical direction, and the resonant wavelength of the DBR is locked on the pumping wavelength, so that the pumping intensity in the resonant cavity is remarkably improved, the excitation threshold value is further reduced, high-efficiency optical pumping excitation is realized, and heat loss is reduced.

Description

Technical Field

[0001] The invention belongs to the field of lasers, and in particular relates to a dual-wavelength composite resonance optically pumped organic laser and a preparation method thereof. Background Art

[0002] Compared with traditional inorganic semiconductor lasers (such as GaAs and InP-based lasers), organic lasers are not only low-cost to process and flexible and compatible, but also have wide-spectrum tunability, covering emission wavelengths from ultraviolet to near-infrared (350–1500nm). They have outstanding potential in flexible optoelectronics, biointegration and low-cost manufacturing.

[0003] Traditional organic lasers usually adopt Fabry-Perot (FP) cavity, distributed reflector (DBR) cavity and distributed feedback (DFB) structure. Organic lasers use organic materials (such as small molecules, polymers or dyes) as laser devices for gain medium. Due to the inherent low carrier mobility of organic materials (usually <10 -3 cm 2 / V·s) and high optical losses (such as scattering and absorption losses) lead to generally high pumping thresholds of organic lasers. High-threshold pumping easily triggers heat accumulation in organic materials, leading to exciton quenching, material phase transition, and even photodegradation of materials, shortening the service life of organic lasers.

[0004] Existing resonant cavity designs (such as DBR cavities and DFB cavities) often only consider the matching degree between the gain spectrum of the organic material and the cavity mode, but do not consider the problem of pump injection. As a result, the pump light in the existing resonator cannot be fully coupled into the organic material. In addition, due to the weak localization ability of the traditional cavity structure for the pump light field, the pump energy cannot be effectively utilized, which not only causes serious energy waste, but also further increases the excitation threshold and thermal effect of the material.

[0005] In summary, a new resonant cavity design is urgently needed to reduce the pumping threshold while taking into account mode matching and thermal management to promote the practical application of organic lasers. Summary of the Invention

[0006] To address the deficiencies of the prior art, the present invention provides an optically pumped organic laser with a dual-wavelength composite resonant cavity structure and a method for preparing the same. By designing a DBR-DFB hybrid structure, while conventionally achieving matching of the gain spectrum of the organic material with the horizontal cavity mode through DFB design, a longitudinal DBR structure is introduced to match the pump wavelength with the longitudinal cavity mode. This significantly increases the intracavity pump intensity while improving the pump injection efficiency, thereby lowering the excitation threshold and achieving highly efficient optical pumping excitation.

[0007] In a first aspect, the present invention provides an optically pumped organic laser based on a dual-wavelength composite resonant cavity, wherein the laser comprises a bottom Bragg reflector, a grating layer, an active layer, a dielectric compensation layer, and a top Bragg reflector, which are arranged in sequence from bottom to top. The bottom Bragg reflector, the grating layer, the active layer, the dielectric compensation layer, and the top Bragg reflector constitute a vertical resonant cavity.

[0008] According to an embodiment of the present invention, the resonant cavity satisfies the resonance enhancement of the pump light wavelength (λ1) and the laser output wavelength (λ2), λ1 is 300-550 nm, and λ2 is 400-760 nm.

[0009] According to an embodiment of the present invention, the incident light forms reflected light between the bottom Bragg reflector and the top Bragg reflector and superimposes on each other. The light field energy is localized in the resonant mode of the DBR, so that the pump light is not only completely coupled into the cavity, but also forms a standing wave field of the pump light in the resonant cavity. Under the field enhancement effect, the light field intensity in the active area reaches 40 to 70 times the amplitude of the injected light field.

[0010] For example, under the excitation of incident light with an excitation wavelength of 532 nm, the emission wavelength of the organic laser is 636 nm; under the excitation of incident light with an excitation wavelength of 445 nm, the emission wavelength of the organic laser is 620 nm.

[0011] According to an embodiment of the present invention, the organic laser further includes a substrate, which is disposed at the bottom of the bottom Bragg reflector.

[0012] According to an embodiment of the present invention, the substrate is made of a material with low absorption of the emission wavelength and the pump source, such as quartz, silicon or sapphire.

[0013] According to an embodiment of the present invention, the reflectivity of the bottom Bragg reflector is greater than 99.7%, and preferably the reflectivity of the bottom Bragg reflector is greater than 99.8%.

[0014] According to an embodiment of the present invention, the thickness of the bottom Bragg reflector is 1000-2000 nm, preferably the thickness of the bottom Bragg reflector is 1000-1500 nm, for example, 1006.1 nm.

[0015] According to an embodiment of the present invention, the reflectivity of the top Bragg reflector is greater than 99.5%, and preferably the reflectivity of the top Bragg reflector is greater than 99.7%.

[0016] According to an embodiment of the present invention, the thickness of the top reflector is 600-1500 nm, preferably the thickness of the top reflector is 600-700 nm, for example 618 nm.

[0017] According to an embodiment of the present invention, the bottom Bragg reflector and the top Bragg reflector include first structure layers and second structure layers that are alternately arranged.

[0018] According to an embodiment of the present invention, the grating layer, the first structure layer, the second structure layer, and the dielectric compensation layer are selected from materials with low absorption to the pump source and emission wavelength.

[0019] According to an embodiment of the present invention, the first structural layer and the second structural layer are made of different materials.

[0020] According to an embodiment of the present invention, the material of the first structural layer in the bottom Bragg reflector is the same as or different from the material of the first structural layer in the top Bragg reflector.

[0021] According to an embodiment of the present invention, the material of the second structure layer in the bottom Bragg reflector is the same as or different from the material of the second structure layer in the top Bragg reflector.

[0022] According to an embodiment of the present invention, the materials of the first structural layer and the second structural layer are selected from at least one of oxides, halides and sulfides, and the oxides include TiO2, Ta2O5, SiO x (x=1-2), TeO2, the halide includes LiF, MgF2, the sulfide includes ZnS, for example, the material of the first structural layer is TiO2 or Ta2O5, and the material of the second structural layer is LiF, SiO2 or TeO2.

[0023] According to an embodiment of the present invention, the refractive index of the first structural layer is n1, and the refractive index of the second structural layer is n2, wherein n1 is 2.0-3.0, and n2 is 1.3-1.7; n1 and n2 are the same or different, for example, different, and preferably n1 is greater than n2.

[0024] According to an embodiment of the present invention, the thickness of the first structure layer in the top Bragg reflector and the thickness of the first structure layer in the bottom Bragg reflector are the same or different, for example, different.

[0025] According to an embodiment of the present invention, the thickness of the second structure layer in the top Bragg reflector and the thickness of the second structure layer in the bottom Bragg reflector are the same or different, for example, different.

[0026] According to an embodiment of the present invention, the optical effective thickness (product of refractive index and thickness) L1 of the first structural layer and the optical effective thickness L2 of the second structural layer are the same or different, and L1 and L2 are related to the pump wavelength λ p The relationship is: L1=M1λ p / 4, L2=M2λ p / 4, where M1 and M2 are odd numbers.

[0027] For example, in the bottom Bragg reflector, the thickness of the first structure layer is 53.6 nm, and the thickness of the second structure layer is 93.7 nm; in the top Bragg reflector, the thickness of the first structure layer is 57.8 nm, and the thickness of the second structure layer is 95.4 nm.

[0028] According to an embodiment of the present invention, in the bottom Bragg reflector and the top Bragg reflector, the total number of the first structural layer and the second structural layer is an odd number, for example, the total number of the bottom Bragg reflector is 21 layers, and the total number of the top Bragg reflector is 11 layers.

[0029] According to an embodiment of the present invention, the total optical effective thickness of the grating layer, the active layer and the dielectric compensation layer is L3 (i.e. the sum of the thicknesses of the grating layer, the active layer and the dielectric compensation layer), and L3 is proportional to the pump wavelength λ. p The relationship is L3=M3λ p / 2, where M3 is an integer.

[0030] According to an embodiment of the present invention, the grating layer material is selected from SiO x (x = 1 to 2), Al2O3 or PMMA; the grating layer adopts a 1st-2nd order hybrid grating structure, wherein the 1st order grating period Λ1 is equal to the lasing wavelength λ s The relationship is: Λ1=λ s / (2n s );2nd-order grating period Λ2 and lasing wavelength λ s The relationship is: Λ1=λ s / (n s ), n s is the effective refractive index of the grating layer at the lasing wavelength.

[0031] According to an embodiment of the present invention, the duty cycle of the grating layer is 30%-70%, preferably the duty cycle of the grating layer is 40%-60%; the optical effective thickness range of the grating layer is 0-λ p / 2; the etching depth of the grating layer is in the range of 30-75nm.

[0032] According to an embodiment of the present invention, the material of the active layer is an organic light-emitting material, selected from one or more organic light-emitting materials such as Alq3:DCM, MEH-PPV, etc., and the optical effective thickness range of the active layer is λ p / 4-λ p / 2.

[0033] According to an embodiment of the present invention, the active layer is a film structure, for example, a single-layer film structure or a film structure formed by alternately stacking several film layers.

[0034] According to an embodiment of the present invention, in a membrane structure formed by alternately stacking several membrane layers, the materials of different membrane layers may be the same or different, preferably different.

[0035] According to an embodiment of the present invention, the thicknesses of different film layers may be the same or different, preferably different.

[0036] According to an embodiment of the present invention, the active layer is an Alq3:DCM film structure or a MEH-PPV film structure.

[0037] According to an embodiment of the present invention, the thickness of the active layer is 50-200 nm, for example, 100 nm or 150 nm.

[0038] According to an embodiment of the present invention, the material of the dielectric compensation layer is selected from SiO x (x=1~2), SiN y (y=1-1.5), PMMA, and LiF; the optical effective thickness range of the dielectric compensation layer is 0-λ p / 2.

[0039] According to an embodiment of the present invention, the material of the dielectric compensation layer is LiF.

[0040] As an example, the bottom Bragg reflector is TiO2 and SiO2 arranged alternately, the grating layer is SiO2, the active layer is Alq3:DCM, the dielectric compensation layer is LiF, and the top Bragg reflector is TeO2 and LiF arranged alternately.

[0041] According to an embodiment of the present invention, the laser has substantially the following Figure 2 or Figure 5 The reflectance spectrum is shown.

[0042] According to an embodiment of the present invention, the laser has substantially the following Figure 3 or Figure 6 The diagram shows the effect of intracavity pump light enhancement.

[0043] According to an embodiment of the present invention, the laser has substantially the following Figure 4 or Figure 7 The output spectrum is shown.

[0044] In a second aspect, the present invention provides a method for preparing an optically pumped organic laser having a dual-wavelength composite resonant cavity structure as described above, the method comprising the following steps:

[0045] S1. Alternately disposing a first structure layer and a second structure layer on the substrate surface to form a bottom Bragg reflector;

[0046] S2. Arrange a grating layer, an active layer and a top Bragg reflector in sequence on the bottom Bragg reflector.

[0047] According to an embodiment of the present invention, sequentially arranging a grating layer on the bottom Bragg reflector comprises the following steps: arranging a grating material on the bottom Bragg reflector and then performing etching.

[0048] It should be noted that, in the present invention, "active region" and "gain region" have the same meaning and can be used interchangeably. In addition, "active layer" and "gain layer" have the same meaning and can be used interchangeably.

[0049] Beneficial effects

[0050] The present invention adds a DBR structure in the vertical direction on the basis of the conventional DFB laser structure, and locks the resonant wavelength of the DBR to the pump wavelength, thereby significantly improving the pump intensity in the resonant cavity, thereby lowering the excitation threshold, achieving high-efficiency optical pumping excitation and reducing heat loss.

[0051] The specific principle is as follows: Conventional optically pumped DFB lasers utilize the periodic structure of the DFB grating to form a specific wavelength (λs = mn s When the photon gain generated by the external pump light excites the gain medium and is greater than the loss, a laser output is formed. Since the gain of the signal light is positively correlated with the intensity of the pump light field in the cavity, increasing the intensity of the pump light in the cavity is obviously beneficial to improving the gain. However, due to interface reflection, the efficiency of the pump light injected into the cavity is usually less than 1, that is, the light field intensity in the cavity is less than the injection light field intensity. The present invention introduces a longitudinal DBR structure on the basis of the conventional DFB laser structure. By introducing a dielectric compensation layer, the resonance wavelength corresponding to the longitudinal cavity mode is precisely controlled to match the pump wavelength. When the present invention is in use, the pump light is injected into the cavity from one side. After the injected pump light enters the cavity, based on the coherent superposition effect of the DBR reflected light, the pump light is not only completely coupled into the cavity, but also forms a standing wave field of the pump light in the resonant cavity, that is, the light field energy is localized in the resonant mode of the DBR. Under the field enhancement effect, the light field intensity of the active area reaches several times (40 to 70 times) the amplitude of the injected light field, thereby realizing localized energy enhancement of the pump light field, thereby lowering the excitation threshold, achieving high-efficiency optical pumping excitation and reducing heat loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 Schematic diagram of the structure of the dual-wavelength composite resonant laser prepared in Example 1 of the present invention.

[0053] Figure 2 This is a reflection spectrum diagram of the dual-wavelength composite resonant laser prepared in Example 1 of the present invention.

[0054] Figure 3 This is a diagram showing the pump light enhancement effect in the cavity of the dual-wavelength composite resonant laser prepared in Example 1 of the present invention.

[0055] Figure 4 This is the output spectrum of the dual-wavelength composite resonant laser prepared in Example 1 of the present invention.

[0056] Figure 5 This is a reflection spectrum diagram of the dual-wavelength composite resonant laser prepared in Example 2 of the present invention.

[0057] Figure 6 This is a diagram showing the pump light enhancement effect in the cavity of the dual-wavelength composite resonant laser prepared in Example 2 of the present invention.

[0058] Figure 7 This is the output spectrum of the dual-wavelength composite resonant laser prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0059] The laser structure of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely exemplary illustrations and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above-mentioned content of the present invention are encompassed within the scope of protection intended by the present invention.

[0060] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0061] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0062] Example 1 Preparation of dual-wavelength composite resonant laser

[0063] Reference Figure 1 As shown, the preparation process of the dual-wavelength composite resonant laser is as follows:

[0064] Step 101: The quartz substrate is ultrasonically cleaned in acetone, isopropyl alcohol, and deionized water in sequence for 15 minutes, and then treated with ultraviolet ozone for 20 minutes.

[0065] Step 102: Place the substrate sheet processed in step 1 into a vacuum coating machine, place TiO2 and SiO2 as evaporation source materials into a crucible, turn on the vacuum system of the coating machine, and when the vacuum degree of the vacuum system of the coating machine reaches below 5E-4Pa, start to alternately evaporate 10.5 pairs of TiO2 and SiO2, where the first and last layers are both TiO2, that is, there are 11 layers of TiO2, each with a thickness of 53.6nm; there are 10 layers of SiO2, each with a thickness of 93.7nm, to obtain a bottom Bragg reflector; then continue to evaporate 50nm of SiO2 on the top surface of the bottom Bragg reflector for preparing the grating layer.

[0066] Step 103: The substrate with the bottom Bragg reflector plated in step 102 is taken out, and a DFB grating structure with a depth of 40 nm and a duty cycle of 0.45 is etched on the SiO2 surface using an electron beam lithography process.

[0067] Step 104: The substrate with the DFB grating in step 103 is cleaned and ozone treated again according to step 1, and then placed in a vacuum coating machine. Alq3 (tris(8-hydroxyquinoline)aluminum) and DCM (dicyanomethylene)-2-methyl-6-(4-dimethylaminophenylvinyl)-4H-pyran) are placed in a crucible as evaporation source materials. The vacuum system of the coating machine is turned on. When the vacuum degree reaches below 5E-4Pa, the coating is carried out according to the following steps: and A 100nm Alq3:DCM active layer was evaporated by dual-source co-evaporation at a rate of .

[0068] Step 105: After the active layer evaporation in step 104 is completed, the coating machine is vented and depressurized, the evaporation source materials are replaced with TeO2 and LiF, and the vacuum system of the coating machine is reopened. When the vacuum degree of the vacuum system of the coating machine reaches below 5E-4Pa, LiF is first used as the dielectric compensation layer material to evaporate 4.6nm LiF; then 6.5 pairs of TeO2 and LiF are alternately evaporated to obtain a top Bragg reflector, wherein the first and last layers are both TeO2, that is, there are 7 layers of TeO2, each layer is 57.8nm thick, and there are 6 layers of LiF, each layer is 95.4nm thick, to obtain a top Bragg reflector.

[0069] Step 106: After the top Bragg reflector is prepared in step 105, the coating machine is vented and the pressure is released, and the device is taken out to obtain a tunable laser.

[0070] The double-resonance laser prepared by the method comprises, from bottom to top, a substrate, a bottom Bragg reflector, a gain region, a dielectric compensation layer and a top Bragg reflector.

[0071] The following is an example of generating 636nm laser by pumping Alq3:DCM material at 532nm. Based on the conventional DFB laser structure, the present invention introduces a longitudinal DBR structure. By introducing a dielectric compensation layer, the resonance wavelength corresponding to the longitudinal cavity mode is precisely controlled to match the pump wavelength. Figure 2 As shown in FIG, the reflection spectrum of the dual-wavelength composite resonant laser prepared in this embodiment has a resonance peak at 532 nm. Figure 3 The distribution of the pump light field in the vertical direction in this embodiment is shown in FIG. Figure 1 In the figure, the pump light is injected into the cavity from the left side and output from the right side. Assuming that the amplitude of the injected light field is 1, based on the coherent superposition of the DBR reflected light, the pump light is not only completely coupled into the cavity, but also forms a standing wave field of the pump light in the resonant cavity, that is, the light field energy is localized in the resonant mode of the DBR. Under the field enhancement effect, the light field intensity in the active area reaches 48 times the amplitude of the injected light field, realizing the localized energy enhancement of the pump light field. Figure 4 Schematic diagram of the generated 636nm laser.

[0072] Example 2 Preparation of dual-wavelength composite resonant laser

[0073] Step 201: This step is the same as step 101.

[0074] Step 202: The substrate sheet processed in step 201 is placed in a vacuum coating machine, TiO2 and SiO2 are placed in a crucible as evaporation source materials, and the vacuum system of the coating machine is turned on. When the vacuum degree of the vacuum system of the coating machine reaches below 5E-4Pa, 10.5 pairs of TiO2 and SiO2 are alternately evaporated, where the first and last layers are both TiO2, that is, there are 11 layers of TiO2, each with a thickness of 44.6nm; there are 15 layers of SiO2, each with a thickness of 76.2nm, to obtain a bottom Bragg reflector; then, 70nm of SiO2 is continuously evaporated on the top surface of the bottom Bragg reflector for preparing the grating layer.

[0075] Step 203: The substrate with the bottom Bragg reflector plated in step 202 is taken out, and a DFB grating structure with a depth of 60 nm and a duty cycle of 0.45 is etched on the SiO2 surface using an electron beam lithography process.

[0076] Step 204: The substrate with the DFB grating in step 203 is cleaned and ozone treated again according to step 201, and then placed in a coater. MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)) (10 mg / ml) dissolved in toluene is spin-coated onto the DFB grating at a speed of 2000 rpm, and annealed at 75°C for 10 minutes to a thickness of about 150 nm to obtain an active layer.

[0077] Step 205: After the active layer evaporation in step 204 is completed, the coating machine is vented and depressurized, the evaporation source materials are replaced with TeO2 and LiF, and the vacuum system of the coating machine is reopened. When the vacuum degree of the vacuum system of the coating machine reaches below 5E-4Pa, LiF is first used as the dielectric compensation layer material to evaporate 42.8nm LiF; then 6.5 pairs of TeO2 and LiF are alternately evaporated to obtain a top Bragg reflector, in which the first and last layers are both TeO2, that is, there are 7 layers of TeO2, each with a thickness of 48nm, and there are 6 layers of LiF, each with a thickness of 79.3nm.

[0078] like Figure 5 The figure shows the reflection spectrum of the dual-wavelength composite resonant laser prepared in this embodiment, with the resonance peak located at 445nm. Figure 6 The distribution of the pump light field in the vertical direction in this embodiment is shown in FIG. Figure 1 In the figure, the pump light is injected into the cavity from the left side and output from the right side. Assuming that the amplitude of the injected light field is 1, based on the coherent superposition of the DBR reflected light, the pump light is not only completely coupled into the cavity, but also forms a standing wave field of the pump light in the resonant cavity, that is, the light field energy is localized in the resonant mode of the DBR. Under the field enhancement effect, the light field intensity in the active area reaches 60 times the amplitude of the injected light field, realizing the localized energy enhancement of the pump light field. Figure 7 Schematic diagram of the generated 620nm laser.

[0079] The above examples illustrate the specific embodiments of the present invention. However, the scope of protection of the present invention is not limited to the above-mentioned exemplary embodiments. Any modifications, equivalent substitutions, improvements, etc. made by those skilled in the art within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. An optically pumped organic laser based on a dual-wavelength composite resonant cavity, characterized in that: The laser comprises a bottom Bragg reflector, a grating layer, an active layer, a dielectric compensation layer and a top Bragg reflector which are arranged in sequence from bottom to top. The bottom Bragg reflector, the grating layer, the active layer, the dielectric compensation layer and the top Bragg reflector constitute a resonant cavity in a vertical direction.

2. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to claim 1, characterized in that: The resonant cavity satisfies the resonance enhancement of the pump light wavelength λ1 and the laser output wavelength λ2. Preferably, the incident light forms reflected light between the bottom Bragg reflector and the top Bragg reflector and superimposes on each other, and the light field energy is localized in the resonant mode of the DBR, so that the pump light is not only completely coupled into the cavity, but also forms a standing wave field of the pump light in the resonant cavity. Under the field enhancement effect, the light field intensity of the active area reaches 40 to 70 times the amplitude of the injected light field.

3. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to claim 1, characterized in that: The reflectivity of the bottom Bragg reflector is greater than 99.7%, and the thickness of the bottom Bragg reflector is 1000-2000 nm. Preferably, the reflectivity of the top Bragg reflector is greater than 99.5%, and the thickness of the top reflector is 600-1500 nm.

4. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to claim 1, characterized in that: The bottom Bragg reflector and the top Bragg reflector include first structure layers and second structure layers that are alternately arranged. Preferably, the materials of the first structural layer and the second structural layer are selected from at least one of oxides, halides and sulfides, and the oxides include TiO2, Ta2O5, SiO x , TeO2, wherein x=1~2, the halide includes LiF, MgF2, and the sulfide includes ZnS. Preferably, the refractive index of the first structural layer is n1, the refractive index of the second structural layer is n2, n1 is 2.0-3.0, and n2 is 1.3-1.

7.

5. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to claim 4, characterized in that: The optical effective thickness L1 of the first structural layer and the optical effective thickness L2 of the second structural layer are the same or different, and L1 and L2 are related to the pump wavelength λ p The relationship is: L1=M1λ p / 4, L2=M2λ p / 4, where M1 and M2 are odd numbers. Preferably, in the bottom Bragg reflector and the top Bragg reflector, the total number of the first structure layer and the second structure layer is an odd number.

6. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to any one of claims 1 to 5, characterized in that: The total optical effective thickness of the grating layer, active layer and dielectric compensation layer is L3, and L3 is equal to the pump wavelength λ p The relationship is L3=M3λ p / 2, where M3 is an integer.

7. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to any one of claims 1 to 5, characterized in that: The grating layer material is selected from SiO x , Al2O3 or PMMA, wherein x=1-2; the grating layer adopts a 1st-order-2nd-order hybrid grating structure, wherein the 1st-order grating period Λ1 is equal to the lasing wavelength λ s The relationship is: Λ1=λ s / (2n s );2nd-order grating period Λ2 and lasing wavelength λ s The relationship is: Λ1=λ s / (n s ), n s is the effective refractive index of the grating layer at the lasing wavelength. Preferably, the duty cycle of the grating layer is 30%-70%, and the optically effective thickness range of the grating layer is 0-λ p / 2; the etching depth of the grating layer is in the range of 30-75nm.

8. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to any one of claims 1 to 5, characterized in that: The material of the active layer is an organic light-emitting material, selected from one or more organic light-emitting materials such as Alq3:DCM, MEH-PPV, etc. The optical effective thickness range of the active layer is λ p / 4-λ p / 2.

9. The optically pumped organic laser based on a dual-wavelength composite resonant cavity according to any one of claims 1 to 5, characterized in that: The material of the dielectric compensation layer is selected from SiO x 、SiN y , PMMA, and LiF, wherein x = 1 to 2, y = 1 to 1.5); the optically effective thickness range of the dielectric compensation layer is 0-λ p / 2.

10. A method for preparing an optically pumped organic laser with a dual-wavelength composite resonant cavity structure according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: S1. Alternately disposing a first structure layer and a second structure layer on the substrate surface to form a bottom Bragg reflector; S2. Arrange a grating layer, an active layer and a top Bragg reflector in sequence on the bottom Bragg reflector.

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