A circularly polarized superluminescent diode and its preparation method and application

Abstract

A circularly polarized superluminescent diode (SLD), its preparation method, and its application relate to the field of circularly polarized SLD technology, solving the problems of low output efficiency, poor spectral compatibility, and system complexity of traditional technologies. The diode has a convex cross-section, with the lower half being a distributed Bragg reflector (DBR), and the upper half comprising, from bottom to top, an ITO cathode, a refractive index control layer, an electron transport layer, a chiral active layer, an electron blocking layer, a hole transport layer, a polyimide insulating layer, and an Ag anode; the rear cavity surface is provided with an Ag high-reflection layer; the DBR consists of alternating layers of high and low refractive index; the refractive index control layer comprises a parylene-C insulating layer and an Al2O3 / ZrO2 nanolayer; and the chiral active layer uses chiral organic small molecules, chiral organometallic complexes, or chiral conjugated polymers. The present invention can be used for optical coherence tomography, providing a new solution for multi-scenario integrated photonic devices.

Description

Technical Field

[0001] The present invention relates to the technical field of circularly polarized SLD, and in particular to a circularly polarized superluminescent diode (SLD), a preparation method thereof, and an application thereof. Background Art

[0002] Optical coherence tomography (OCT) relies on a broad-spectrum, low-coherence light source to detect the internal structures of biological tissues or industrial materials with micron-level resolution. Superluminescent diodes (SLDs) are the core light source for OCT systems due to their broad-spectrum characteristics. However, the unpolarized or linearly polarized light output by conventional SLDs is susceptible to multiple scattering interference when penetrating highly scattering media, such as biological tissues or complex industrial materials. This results in reduced imaging contrast and deep signal attenuation.

[0003] Circularly polarized light, due to its spiral wavefront characteristics, can effectively suppress scattering noise and significantly improve the imaging signal-to-noise ratio and penetration depth of OCT. For example, in cardiovascular plaque detection, circularly polarized light can accurately identify vulnerable plaque structures by distinguishing the polarization characteristics of the fibrous cap and the lipid core, reducing the risk of misdiagnosis. In the non-destructive testing of industrial multi-layer transparent materials (such as optical films or liquid crystal screens), circularly polarized SLD can be combined with multi-wavelength light sources to achieve microstructural analysis of anisotropic materials and improve defect identification accuracy. In addition, dynamically adjustable circularly polarized light can adapt to the multimodal imaging requirements of OCT systems, enhancing the signal extraction capability of specific depths or regions by adjusting the circular polarization direction, providing technical support for intelligent diagnosis and real-time monitoring.

[0004] However, traditional circularly polarized light relies heavily on external polarizers or metasurface structures. Polarizers convert linearly polarized light into circularly polarized light through a combination of a quarter-wave plate and a linear polarizer. However, this introduces approximately 50% optical power loss, significantly reducing the output efficiency of the SLD. Furthermore, it is difficult to match the wavelength sensitivity of a broad-spectrum light source, resulting in a decrease in polarization purity with wavelength shift. While metasurface structures can directly control polarization states through subwavelength optical elements, they require extremely high machining precision (such as nanoscale periodic structures) and are sensitive to the angle of the incident light. This can easily lead to polarization distortion in SLDs with large divergence angles, increasing system complexity and cost.

[0005] In contrast, circularly polarized SLDs based on chiral materials can directly generate high-purity circularly polarized light during the emission process through the material's intrinsic chirality-induced spin-selective effect, eliminating the need for external optical components, greatly simplifying optical path design and reducing insertion loss. For example, chiral perovskite quantum dots or organic semiconductor materials can achieve asymmetric, efficient circularly polarized emission through molecular-scale chirality transfer and multi-level structural amplification, while maintaining a high photoluminescence quantum yield. Such materials can control the emission wavelength through bandgap engineering, adapting to the OCT system's demand for multi-band light sources. They also achieve direct output of electrically induced circularly polarized light through efficient injection of spin-polarized carriers, providing a new path for the miniaturization and integration of SLDs.

[0006] Therefore, the circularly polarized SLD based on chiral materials combines high efficiency, wide spectral compatibility and compact structure, and is an ideal solution to break through the bottleneck of traditional circularly polarized SLD technology. Summary of the Invention

[0007] In order to solve the problems of low output efficiency, poor spectral compatibility and system complexity of traditional circular polarization technology, the present invention proposes a circularly polarized superluminescent diode and its preparation method and application.

[0008] The technical solutions of the present invention are as follows:

[0009] A circularly polarized superluminescent diode (SLLED), wherein the cross-section of the SLLED is convex; the lower half of the convex shape is a distributed Bragg reflector (DBR); the upper half comprises, from bottom to top, an ITO cathode, a refractive index control layer, an electron transport layer, a chiral active layer, an electron blocking layer, a hole transport layer, a polyimide insulating layer, and an Ag anode; the rear cavity surface of the SLLED is provided with an Ag high reflective layer;

[0010] The distributed Bragg reflector (DBR) consists of several pairs of alternating layers of high refractive index and low refractive index;

[0011] The refractive index regulating layer includes a parylene-C insulating layer and an Al2O3 / ZrO2 nanolayer;

[0012] The chiral active layer uses chiral organic small molecules, chiral organic metal complexes or chiral conjugated polymers as circularly polarized luminescent materials.

[0013] Preferably, the distributed Bragg reflector (DBR) is composed of more than 10 pairs of alternating layers of high refractive index and low refractive index.

[0014] Preferably, the high refractive index layer in the alternating layers of high refractive index and low refractive index is selected from TiO2, HfO2, Al2O3, and the low refractive index material layer is selected from SiO2, MgF2.

[0015] Preferably, the electron transport layer is made of ZnO material; the electron blocking layer is made of TAZ (3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole material); and the hole transport layer is made of a material obtained by doping 1,1-bis(4-(N,N-di-p-toluylamino)phenyl)cyclohexane with 4% F6-TCNNQ.

[0016] Preferably, the thickness of the ITO cathode is 50 nm; the thickness of the refractive index control layer is 200 nm; the thickness of the electron transport layer is 50 nm; the thickness of the chiral active layer is 100 nm; the thickness of the electron blocking layer is 50 nm; the thickness of the hole transport layer is 50 nm; the thickness of the polyimide insulating layer is 100 nm; the thickness of the Ag high reflective layer is 100 nm; and the thickness of the Ag anode is 100 nm.

[0017] Preferably, the chiral organic small molecule is selected from one of (R / S)-C-DpCpN-Trz, a perylene imide derivative, a (2-dimethylborane)phenyl cyclopentane derivative m-BPhNMe2-Cp, and a chiral bicyclic molecule SCPP[8].

[0018] Preferably, the chiral perovskite material is selected from one of (R / S)-2-methylpiperazine lead bromide single crystal and MAPbI3 perovskite nanocrystal colloid.

[0019] Preferably, the chiral conjugated polymer is selected from one of polyfluorene-boron nitrogen polymer R / S-PBN and cellulose acetate butyrate / polyacetylene complex CAB / P1.

[0020] The present invention also provides a method for preparing the circularly polarized superluminescent diode, comprising the following steps:

[0021] S1, using PECVD / sputtering to alternately deposit low refractive index layers and ALD / reactive sputtering to deposit high refractive index layers to construct a vertically stacked distributed Bragg reflector (DBR);

[0022] S2. Pre-plating an ITO cathode on a distributed Bragg reflector (DBR), and then depositing parylene-C (insulating layer) and an Al2O3 / ZrO2 nanolayer on the ITO cathode to construct the refractive index control layer to form a multi-layer transparent structure; improving the coupling efficiency between light and the DBR grating.

[0023] S3, dissolving zinc acetate and ethanolamine in 2-methoxyethanol, spin coating at 3000 rpm for 50 seconds, and then annealing at 200°C for 2 hours to obtain an electron transport layer;

[0024] S4, selecting a suitable material according to the luminescent wavelength and luminescent efficiency of the chiral material, and preparing a chiral active layer on the electron transport layer by thermal evaporation or solution spin coating;

[0025] S5, through the organic coating machine in 10 -5 Torr deposition of TAZ (3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole) and 1,1-bis(4-(N,N-di-p-toluamino)phenyl)cyclohexane + 4% F6-TCNNQ doping materials to obtain electron blocking layer and hole transport layer;

[0026] S6, using plasma-assisted molecular layer deposition technology (20 kHz low-power plasma, 150 ° C) to prepare the polyimide insulating layer;

[0027] S7. Deposit an Ag anode on the top by thermal evaporation and deposit an Ag high reflective layer on the rear cavity surface.

[0028] The present invention also provides an application of the circularly polarized superluminescent diode in optical coherence tomography technology.

[0029] Compared with the prior art, the present invention has the following specific beneficial effects:

[0030] 1. Compared to circularly polarized SLDs that rely on polarizers or metasurfaces to achieve circular polarization, this invention directly generates efficient circularly polarized light through the intrinsic chirality of the material, avoiding the insertion loss (light loss >50%) caused by polarizers in traditional solutions or the complex nanofabrication requirements of metasurfaces. It utilizes the unique optical activity of chiral materials to achieve efficient generation of circularly polarized light. The molecular or structural helical properties of chiral materials can specifically couple with photon spin angular momentum. During the carrier recombination luminescence process, by regulating chiral parameters (such as molecular helicity and structural period), the proportion of circularly polarized light radiation with a specific rotation direction is significantly increased. Compared to traditional achiral materials, this invention solves the problems of low purity and poor efficiency of circularly polarized light from the very nature of luminescence, breaking through the limitations of traditional devices that rely on external polarizers, and providing core innovations at the material level for the intrinsic generation of circularly polarized light.

[0031] 2. The present invention provides a device architecture combining a multi-level heterostructure and an optical microcavity based on the coupling characteristics of chiral materials and semiconductors. By precisely designing the energy band matching and carrier transport path of the chiral material / semiconductor interface, an integrated channel for efficient carrier injection-recombination-polarized radiation is constructed. Specifically, an optical microcavity structure is formed between the bottom DBR and the upper Ag anode. By utilizing the resonance effect, the light field energy of the circularly polarized light of a specific wavelength emitted by the chiral material is directionally accumulated in the cavity and its output intensity is significantly enhanced. Through strict resonance conditions, the feedback and mode selection of circularly polarized light are enhanced, non-target wavelengths and non-desired polarization modes are suppressed, especially non-polarization modes, thereby improving the output intensity and purity of the output circularly polarized light, and reducing non-radiative recombination losses through interface regulation, ultimately achieving a synergistic improvement in luminous efficiency and polarization purity.

[0032] 3. The collaborative design of the chiral material and self-assembling polymer of the present invention not only achieves the compatibility of high asymmetry factor and external quantum efficiency, but also enhances the luminous intensity and bandwidth characteristics through the superradiant effect. Traditional polarizer solutions have difficulty in achieving both performance and stability due to spectral broadening and efficiency attenuation. In addition, the dynamic self-assembly ability of the chiral material supports in-situ regulation of wavelength and polarization state, breaking through the limitations of traditional polarization structures that fix wavelength / polarization mode, and providing a more efficient, compact and functionally controllable solution for multi-scenario integrated photonic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the three-dimensional structure of a circularly polarized superluminescent diode provided by the present invention;

[0034] Figure 2 This is a schematic diagram of the cross-sectional structure of the circularly polarized superluminescent diode provided by the present invention.

[0035] Description of reference numerals:

[0036] 1. Distributed Bragg reflector, 2. ITO cathode, 3. Refractive index control layer, 4. Electron transport layer, 5. Chiral active layer, 6. Electron blocking layer, 7. Hole transport layer, 8. Polyimide insulating layer, 9. Ag high reflective layer, 10. Ag anode. DETAILED DESCRIPTION

[0037] This invention directly generates highly efficient circularly polarized light through the intrinsic chirality of the material, avoiding the insertion loss of polarizers or the complex nano-fabrication requirements of metasurfaces in traditional solutions. It utilizes the unique optical activity of chiral materials to achieve efficient generation of circularly polarized light. The circularly polarizing materials are selected as follows:

[0038] (1) Chiral organic small molecules:

[0039] Molecules are designed by introducing chiral centers (such as carbon stereocenters), axial chirality (such as helical structures), or planar chirality. For example, R / S-5 (binaphthyl-pyrene derivative) modifies the pyrene structure with a chiral binaphthyl group to form a fluorescent emitter. Representative materials include: (R / S)-C-DpCpN-Trz, perylene imide derivatives, (2-dimethylborane)phenylcyclohexane derivative m-BPhNMe2-Cp, and the chiral bicyclic molecule SCPP[8].

[0040] (2) Chiral organometallic complexes:

[0041] Chiral organic cation embedding: Chiral ammonium salts (such as S / R-1-(1-naphthyl)ethylammonium iodide) are introduced into the perovskite structure, forming quasi-two-dimensional or layered structures through solution methods (spin coating, solvothermal). For example, (R / S-MBA)2PbI4 acts as a chiral hole transport layer, combined with achiral CsPbX3 nanocrystals, to achieve circularly polarized fluorescence emission through chirality-induced spin selectivity. Multidimensional chiral structures: Enhanced chirality transfer to the inorganic framework is achieved by manipulating the dimensionality (2D / 3D) and crystallization conditions. Representative materials include (R / S)-2-methylpiperazine lead bromide single crystals and MAPbI3 perovskite nanocrystal colloids.

[0042] (3) Chiral conjugated polymers:

[0043] Chiral side chain modification: Introducing chiral side chains into conjugated polymer backbones (such as polyfluorene) induces supramolecular helical structures. For example, c-PFBT (polyfluorene-benzothiadiazole copolymer modified with chiral side chains) can be formed into helical fibers through solution processing. Chiral additive blending: Mixing achiral polymers (such as F8BT) with chiral small molecules (such as helical aromatics and BINOL derivatives) creates chirality through self-assembly. Representative materials include polyfluorene-boron nitrogen polymer R / S-PBN and cellulose acetate butyrate / polyacetylene composite CAB / P1.

[0044] All of the above materials are materials with detailed preparation processes described in public literature or materials that are commercially available.

[0045] Among them, (R / S)-C-DpCpN-Trz can be purchased from Suzhou Yaco Technology Co., Ltd., perylene imide derivatives can be purchased from Shanghai Nafu Biotechnology Co., Ltd., the preparation of (2-diboron)phenyl cyclopeptide derivative m-BPhNMe2-Cp is described in the doctoral thesis of Shandong University "Research on Boron-modified [2.2] Cyclopeptide Organic Luminescent Materials", and the chiral bicyclic molecule SCPP[8] can be purchased from Delta Bio.

[0046] (R / S)-2-Methylpiperazine lead bromide single crystals can be purchased from Shanghai Nafu Biotechnology Co., Ltd., and MAPbI3 perovskite nanocrystal colloids can be purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0047] Polyfluorene-boron nitrogen polymer R / S-PBN can be purchased from Suzhou Yaco Technology Co., Ltd., and cellulose acetate butyrate / polyacetylene composite CAB / P1 can be purchased from Trinseo Polymer (Zhangjiagang) Co., Ltd.

[0048] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as limiting the present invention.

[0049] Example 1.

[0050] This example prepares a visible light (400-700 nm) circularly polarized superluminescent diode. The specific operations are as follows:

[0051] S1, using PECVD / sputtering to alternately deposit MgF2 and ALD / reactive sputtering to deposit TiO2, with a total of 15 pairs of alternating depositions to construct a vertically stacked distributed Bragg reflector 1;

[0052] S2, pre-plating a 50nm ITO cathode 2 on the distributed Bragg reflector 1, and then depositing a 100nm parylene-C insulating layer and a 100nm Al2O3 / ZrO2 nanolayer on the ITO cathode 2 to construct the refractive index control layer 3 to form a multi-layer transparent structure;

[0053] S3, dissolving zinc acetate and ethanolamine in 2-methoxyethanol, spin coating at 3000 rpm for 50 seconds, and then annealing at 200°C for 2 hours to obtain an electron transport layer 4 with a thickness of 50 nm;

[0054] S4, spin-coating the perylene imide derivative MPBI as the chiral active layer 5 on the electron transport layer 4 by thermal evaporation or solution spin coating;

[0055] S5, through the organic coating machine in 10 -5 Torr deposition of 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole and 1,1-bis(4-(N,N-di-p-toluamino)phenyl)cyclohexane + 4% F6-TCNNQ dopant material in sequence to obtain a 50 nm electron blocking layer 6 and a 50 nm hole transport layer 7;

[0056] S6, using plasma-assisted molecular layer deposition technology to prepare a 100 nm thick polyimide insulating layer 8;

[0057] S7. Deposit a 100 nm thick Ag anode 10 on the top by thermal evaporation, and deposit a 100 nm thick Ag high reflective layer 9 on the rear cavity surface.

[0058] The DBR structure in this embodiment forms a transverse Bragg reflector waveguide (BRW). This periodic refractive index variation confines the optical field, enhancing photon feedback efficiency and reducing light leakage into inactive areas. The low refractive index of the ITO cathode reduces optical loss, enhances refractive index contrast, and optimizes the total internal reflection mode. It also reduces series resistance, reduces Joule heating at high current densities, and improves device stability. The refractive index control layer improves the grating coupling efficiency with the DBR through refractive index manipulation. The electron transport layer efficiently injects electrons into the chiral active layer, pre-filling the electrons to partially bleach the ground state absorption, lowering the optical gain threshold and suppressing Auger recombination. Due to their helical configuration or the presence of chiral centers, the molecules or polymers in the chiral active layer can selectively emit left-handed (L-CPL) or right-handed (R-CPL) circularly polarized light, exhibiting asymmetric luminescence characteristics. The electron blocking layer, with its high LUMO energy level, effectively blocks electrons from entering the hole transport layer while also providing thermal stability. The hole transport layer lowers the hole injection barrier by matching energy levels, promoting efficient hole injection from the anode into the light-emitting layer. The polyimide insulating layer suppresses ohmic contact between the electrode and the semiconductor layer. The Ag highly reflective layer and the front-cavity high-transmittance layer form an SLD resonator, suppressing resonant cavity feedback and facilitating broad spectral output. The Ag anode acts as a reflector to enhance light field confinement (forming a lateral cavity with the DBR). Due to the high absorption loss of silver, TM mode photons are suppressed and TE mode photons are reflected, extending the photon propagation path within the active layer and promoting stimulated emission.

[0059] Example 2.

[0060] This example prepares a visible light (400-700nm) circularly polarized superluminescent diode. The differences between this example and Example 1 in terms of operating steps include:

[0061] S4, spin-coating cellulose acetate butyrate / polyacetylene composite CAB / P1 on the electron transport layer 4 by thermal evaporation or solution spin coating as the chiral active layer 5. The remaining operations are the same as those in Example 1.

[0062] Example 3.

[0063] This example prepares a near-infrared (780-800 nm) circularly polarized superluminescent diode. The differences between this example and Example 1 in terms of operating steps include:

[0064] S1. SiO2 is alternately deposited by PECVD / sputtering, and Al2O3 is alternately deposited by ALD / reactive sputtering, with a total of 21 pairs of alternating depositions to construct a distributed Bragg reflector 1 with a vertically stacked structure; S4. MAPbI3 perovskite nanocrystal colloid is spin-coated on the electron transport layer 4 as a chiral active layer 5 by thermal evaporation or solution spin coating.

[0065] The remaining operations are the same as those in Example 1.

[0066] Effect example 1.

[0067] The optical spectral characteristics of the circularly polarized superluminescent diodes obtained in Examples 1 to 3 and common laser diodes on the market were tested respectively, including emission spectrum testing and temporal coherence length calculation.

[0068] Emission spectrum test method:

[0069] The device was placed in a temperature-controlled fixture and operated at a constant drive current. An optical fiber was used to couple the emitted light into a high-resolution fiber spectrometer. The emission spectra were measured at different drive currents, focusing on the peak wavelength, full width at half maximum (FWHM), and spectral smoothness and symmetry.

[0070] Calculation method of temporal coherence length:

[0071] Based on the emission spectrum data, the formula Lc=λc 2 / (n*Δλ), where λc is the center wavelength, Δλ is the spectral bandwidth (FWHM), and n is the refractive index of the medium (usually the effective refractive index of the device's light-emitting surface or the refractive index of air ≈ 1). Alternatively, direct measurement can be used: a Michelson interferometer is used to directly measure the coherence length.

[0072] The test results are shown in Table 1.

[0073] Table 1

[0074]

[0075] Effect example 2.

[0076] The circular polarization characteristics of the circularly polarized superluminescent diodes obtained in Examples 1 to 3 were tested respectively.

[0077] 1. Circular polarization degree:

[0078] Use the standard Stokes parameter measurement method. Direct the device's output light through a quarter-wave plate (with a known fast axis direction). Place a rotatable linear polarizer after the quarter-wave plate. Use a power meter or spectrometer (integrating mode) to measure the light intensities (I0, I45, I90, and I135) transmitted through the linear polarizer at 0°, 45°, 90°, and 135°.

[0079] Calculate the Stokes parameters: S0 = I0 + I90, S1 = I0 - I90, S2 = I45 - I135, S3 = 2I_cp - S0, where I_cp is the left-handed or right-handed light intensity.

[0080] Calculate the degree of circular polarization (DoCP) = |S3| / S0*100%.

[0081] 2. Comparative test:

[0082] A comparison device with the same structure but not containing a chiral material layer was prepared, and the same Stokes parameter measurement was performed on the comparison device to calculate the circular polarization rate.

[0083] The test results are shown in Table 2.

[0084] Table 2

[0085]

[0086] Effect example 3.

[0087] The electro-optical properties of the circularly polarized superluminescent diodes obtained in Examples 1 to 3 were tested respectively.

[0088] The device is mounted on a temperature-controlled heat sink and a source measure unit (SMU) is used to apply a drive current (I) while measuring the forward voltage (V). A calibrated large-area photodetector (or integrating sphere + detector) is used to directly measure the total optical output power (Popt) of the device.

[0089] Test results:

[0090] The total optical output power (Popt) of the devices in Examples 1 to 3 all reached a continuous wave output power of several milliwatts to tens of milliwatts at a safe operating current of 100 to 200 mA.

[0091] Effect example 4.

[0092] The aging characteristics of the circularly polarized superluminescent diodes obtained in Examples 1 to 3 were tested respectively.

[0093] Operate the device continuously at constant current and constant temperature for hundreds of hours. Regularly monitor the output optical power and DoCP.

[0094] The test shows that the output optical power and DoCP decay slightly over time, demonstrating good initial reliability.

[0095] The above test results demonstrate that the diode provided by the present invention can achieve high-purity direct circularly polarized light emission without the need for any external optical components (such as a quarter-wave plate and linear polarizer combination). Under electrical pumping, the device itself can directly emit high-purity circularly polarized light with a degree of circular polarization (DoCP) >90%. Operating in a superluminescent mode, the device boasts an emission spectrum bandwidth significantly wider than that of a laser diode, reaching 20–50 nm or even wider, and a short temporal coherence length on the order of tens of microns, effectively suppressing optical coherence noise. In continuous-wave mode, it can deliver circularly polarized light output power ranging from a few milliwatts to tens of milliwatts, meeting practical application requirements. As an electrically pumped semiconductor device, the device is compact and easily integrated into existing optoelectronic systems, with a simple drive mechanism (similar to LEDs / LDs). The handedness of the emitted light (left-handed LCP or right-handed RCP) is determined by the integrated chiral material structure and can be precisely controlled through material design. Key performance parameters remain relatively stable within a reasonable temperature and operating current range, demonstrating preliminary reliability.

[0096] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A circularly polarized superluminescent diode, characterized in that: The cross-section of the circularly polarized superluminescent diode is a convex shape; the lower half of the convex shape is a distributed Bragg reflector (1), and the upper half includes, from bottom to top, an ITO cathode (2), a refractive index control layer (3), an electron transport layer (4), a chiral active layer (5), an electron blocking layer (6), a hole transport layer (7), a polyimide insulating layer (8), and an Ag anode (10); the rear cavity surface of the circularly polarized superluminescent diode is provided with an Ag high reflective layer (9); The distributed Bragg reflector (1) is composed of a plurality of pairs of alternating layers of high refractive index and low refractive index; The refractive index regulating layer (3) comprises a parylene-C insulating layer and an Al2O3 / ZrO2 nanolayer; The chiral active layer (5) is a circularly polarized luminescent material made of chiral organic small molecules, chiral perovskite materials or chiral conjugated polymers.

2. The circularly polarized superluminescent diode according to claim 1, wherein: The distributed Bragg reflector (1) is composed of more than 10 pairs of alternating layers of high refractive index and low refractive index.

3. The circularly polarized superluminescent diode according to claim 2, characterized in that: The high refractive index layer in the high refractive index and low refractive index alternating layers is selected from TiO2, HfO2, and Al2O3, and the low refractive index material layer is selected from SiO2 and MgF2.

4. The circularly polarized superluminescent diode according to claim 1, wherein: The electron transport layer (4) is made of ZnO material; the electron blocking layer (6) is made of 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole material; and the hole transport layer (7) is made of a material obtained by doping 1,1-bis(4-(N,N-di-p-toluylamino)phenyl)cyclohexane with 4% F6-TCNNQ.

5. The circularly polarized superluminescent diode according to claim 1, wherein: The thickness of the ITO cathode (2) is 50 nm; the thickness of the refractive index control layer (3) is 200 nm; the thickness of the electron transport layer (4) is 50 nm; the thickness of the chiral active layer (5) is 100 nm; the thickness of the electron blocking layer (6) is 50 nm; the thickness of the hole transport layer (7) is 50 nm; the thickness of the polyimide insulating layer (8) is 100 nm; the thickness of the Ag high reflective layer (9) is 100 nm; and the thickness of the Ag anode (10) is 100 nm.

6. The circularly polarized superluminescent diode according to claim 1, wherein: The chiral organic small molecule is selected from one of (R / S)-C-DpCpN-Trz, a perylene imide derivative, a (2-dimethylborane)phenyl cyclopentane derivative m-BPhNMe2-Cp, and a chiral bicyclic molecule SCPP[8].

7. The circularly polarized superluminescent diode according to claim 1, wherein: The chiral perovskite material is selected from liquid crystal template chiral perovskite elastic film Lumin-CLCE, (R / S)-2-methylpiperazine lead bromide single crystal, R / S-3BrMBA2PbI4 chiral layered perovskite, DMSO passivated Cs2AgBi 0.2 In 0.8 One of Cl6, MAPbI3 perovskite nanocrystal colloids.

8. The circularly polarized superluminescent diode according to claim 1, wherein: The chiral conjugated polymer is selected from one of polyfluorene-boron nitrogen polymer R / S-PBN and cellulose acetate butyrate / polyacetylene complex CAB / P1.

9. A method for preparing a circularly polarized superluminescent diode according to any one of claims 1 to 7, characterized in that: The steps include: S1, using PECVD / sputtering to alternately deposit low refractive index layers and ALD / reactive sputtering to deposit high refractive index layers to construct a vertically stacked distributed Bragg reflector (1); S2, pre-plating an ITO cathode (2) on the distributed Bragg reflector (1), and then depositing a parylene-C insulating layer and an Al2O3 / ZrO2 nanolayer on the ITO cathode (2) to construct the refractive index control layer (3) to form a multi-layer transparent structure; S3, dissolving zinc acetate and ethanolamine in 2-methoxyethanol, spin coating at 3000 rpm for 50 seconds, and then annealing at 200°C for 2 hours to obtain an electron transport layer (4); S4, preparing a chiral active layer (5) on the electron transport layer (4) by thermal evaporation or solution spin coating; S5, through the organic coating machine in 10 -5 Torr sequentially deposited 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole and 1,1-bis(4-(N,N-di-p-toluylamino)phenyl)cyclohexane+4% F6-TCNNQ doping materials to obtain an electron blocking layer (6) and a hole transport layer (7); S6, preparing a polyimide insulating layer (8) using plasma-assisted molecular layer deposition technology; S7. Deposit a Ag anode (10) on the upper side by thermal evaporation, and deposit a Ag high reflective layer (9) on the rear cavity surface.

10. Application of the circularly polarized superluminescent diode according to claims 1 to 8 in optical coherence tomography technology.

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