Silicon carbide color center laser processing and multimodal real-time in-situ detection optical device

Abstract

This invention relates to an optical device for real-time in-situ detection of silicon carbide color centers using laser processing, belonging to the fields of quantum optics and quantum precision measurement. The invention comprises a laser processing system, a confocal laser transmission and spectral detection module, a single-photon source detection module, a fluorescence imaging module, and a data acquisition, processing, and control system. The laser processing system emits a single-pulse laser to process the pre-treated silicon carbide wafer. After femtosecond laser irradiation, the defect location is excited by switching the light source. The confocal laser transmission and spectral detection module and the single-photon source detection module detect whether color centers are generated and whether the prepared color centers are single-photon sources. The fluorescence imaging module monitors the color center formation process in real time and transmits the acquired results to a host computer for processing and analysis. This invention enables real-time and in-situ monitoring of color center formation, improving color center yield and processing efficiency while ensuring that the final processed color centers are more likely to become high-quality single-photon sources.

Description

Technical Field

[0001] This invention relates to the fields of quantum optics and quantum precision measurement, specifically to an optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers, applicable to applications in the processing and detection of silicon carbide color centers. Background Technology

[0002] In today's era, with the accelerating pace of social informatization, massive amounts of data are sweeping across human society like a tidal wave, giving rise to the emerging discipline of quantum information science based on quantum systems. Quantum communication, quantum sensing, and quantum computing have become new battlegrounds for fierce international competition.

[0003] Constructing high-performance, stable, and reliable quantum systems is the foundation for the long-term development of quantum technology. Currently, numerous physical systems can serve as carriers of quantum information, including superconducting systems, ion trap systems, and solid-state color center systems. Among these systems, solid-state color center systems cleverly combine the excellent optical and spin properties of color centers with the significant advantages of solid-state carriers, such as ease of integration and strong scalability, making them one of the most promising quantum platforms for current applications.

[0004] Silicon carbide (SiC), as a third-generation wide-bandgap semiconductor, is widely used in microelectronics, aerospace, high-power devices, and other industries. Silicon carbide materials offer high-quality wafer fabrication and epitaxial growth capabilities, as well as mature micro- and nano-fabrication technologies. Its color center emission range is extremely broad, extending from the visible light region to the infrared band. It possesses a rich variety of color centers, with silicon vacancy and double-vacancy color centers being the most studied. These centers can achieve spin state polarization and readout using lasers at room temperature and can be manipulated using microwaves. These properties give it unparalleled application prospects in many key fields such as quantum information technology, high-precision detection, and biosensoring, and it is expected to bring about groundbreaking changes and leaps in these fields.

[0005] Currently, the integration of SiC color center processing and inspection systems is not high. In the past, the processing and inspection systems were separate, lacking processing and real-time in-situ inspection methods, resulting in low efficiency. Due to the incompleteness of the system, samples need to be moved constantly, which can easily cause sample contamination. Furthermore, if a batch of samples is found to be non-compliant after processing and inspection, the entire batch of materials will be wasted. The inability to provide real-time feedback results will lead to a lengthy and costly process optimization process. Moreover, due to the lack of real-time monitoring methods, the understanding of the physical changes during color center processing is limited. The low integration of processing and inspection systems will result in problems such as low color center yield and processing efficiency. Summary of the Invention

[0006] To address the problems of uncontrollable processing quality, low color center yield, low processing and optimization efficiency, and insufficient understanding of the microscopic formation mechanism of color centers caused by the ineffective integration of existing color center processing and detection devices, this invention aims to provide an optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers. This device utilizes a femtosecond laser to process and prepare color centers through a processing optical path. The laser is connected to a computer for control of operation, parameter setting, and dynamic adjustment. The color center formation process is observed in real-time through continuous acquisition triggered synchronously with the laser by an EMCCD. The integrated processing and detection system can immediately detect the formation of color centers after processing and verify whether they are single-photon sources. Processing parameters are adjusted in real-time based on feedback results, improving color center yield and processing efficiency, and avoiding potential sample contamination. Furthermore, fluorescence imaging combined with a fluorescence imaging system in the host computer allows for image processing of the captured fluorescence signals to improve color center resolution.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] The optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers disclosed in this invention includes a laser processing system, a confocal laser transmission and spectral detection module, a single-photon source detection module, a fluorescence imaging module, and a data acquisition, processing, and control system. The laser processing system emits a single-pulse laser to process the pre-processed SiC wafer. The SiC wafer is irradiated with a femtosecond laser to generate defects. The source is switched to excite the defect position. The material absorbs photon energy and generates electronic transitions. The emitted fluorescence is detected by the confocal laser transmission and spectral detection module and the single-photon source detection module to determine whether color centers are generated and whether the prepared color centers are single-photon sources. The fluorescence imaging module monitors the formation process of color centers in real time and transmits the acquisition results to a host computer for processing and analysis.

[0009] The laser processing system is used to process samples with defects. It generates 1030nm pulsed laser through a femtosecond laser, adjusts the polarization state with a half-wave plate, expands the beam with a beam expander, controls the laser energy with an aperture, and achieves precise positioning and processing in conjunction with a scanning galvanometer and an electric displacement stage. A CCD monitors the surface morphology of the processed surface in real time.

[0010] The confocal laser transmission and spectral detection module is used to excite defects and perform fluorescence collection and spectral detection. A 780nm laser is generated by a pulsed laser, a short-pass dichroic mirror transmits the laser and reflects the fluorescence, a filter group filters out light outside the fluorescence wavelength, and the light is transmitted to a spectrometer through a coupler and optical fiber for fluorescence spectral characterization, thereby determining whether a color center has been generated.

[0011] The single-photon source detection module is used to detect whether the color center is a single-photon source. The coupling lens couples the photon sequence into a 50:50 single-mode split fiber, which is then connected to two photon detectors for detection. The electrical pulses generated by the detectors are sent to the time-correlated single-photon counting card (TCSPC). The TCSPC records the arrival time of each electrical pulse signal in the two channels. Finally, by analyzing the measured time data, the self-correlation information of the photon sequence is obtained. The second-order correlation function is calculated, and if the value is less than 0.5, it is considered to be a single-photon source.

[0012] The fluorescence imaging module is used to image the color centers. The EMCCD is synchronously triggered with the pulsed laser to acquire image sequences of individual color centers generated under each pulse excitation, and to monitor the formation process of the color centers in real time.

[0013] The data acquisition, processing, and control system is used to control the laser parameter settings and analyze and process the acquired signals. The host computer controls the operation of each module and is used to realize laser parameter settings, acquisition spectrum and photon sequence signal analysis, real-time monitoring of the fluorescence imaging process, and acquisition image processing.

[0014] Furthermore, during the processing, the laser processing system dynamically adjusts the power, repetition rate, focusing position, and scanning speed of the femtosecond pulse laser according to a preset program or based on real-time sample processing information fed back by the CCD, ensuring the accuracy and stability of color center induction.

[0015] Furthermore, in the confocal laser transmission and spectral detection module, the laser generated by the laser is transmitted to the sample to excite fluorescence through a dichroic mirror. After the fluorescence is reflected by the dichroic mirror, it passes through a filter to remove light outside the fluorescence band, and then enters the spectrometer for detection through a coupling mirror. The confocal optical path ensures that the excitation light and the detection light are confocal, thereby improving the accuracy and resolution of spectral detection.

[0016] Furthermore, during detection, the single-photon source detection module uses a single-mode splitting fiber to precisely split the light into two high-sensitivity photon detectors. The photon detectors convert the photon signals into electrical signals and transmit them to the TCSPC. By transmitting the photon sequence to the host computer, the second-order correlation function of the photons is calculated to determine whether the color center has single-photon source characteristics.

[0017] Furthermore, during the imaging process, the fluorescence imaging module synchronously triggers the EMCCD and pulsed laser to continuously acquire fluorescence images under each pulse. Under the control of the imaging parameter adjustment unit, parameters such as exposure time and gain are adjusted according to sample characteristics and imaging requirements. The fluorescence imaging optical path component ensures the stability of the imaging optical path and acquires clear, high-resolution images of silicon carbide color centers. The image data is transmitted to the data acquisition, processing, and control module for storage, data processing, and analysis.

[0018] Furthermore, the data acquisition, processing, and control system is used to control the laser parameter settings and analyze and process the acquired signals. The host computer controls the operation of each module, including laser parameter settings, signal analysis such as acquired spectra and photon sequences, real-time monitoring of the fluorescence imaging process, and image processing.

[0019] Beneficial effects:

[0020] 1. The optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers disclosed in this invention integrates the detection optical path and the processing optical path, and can adjust the processing parameters in real time according to the detection results. It also avoids the need to refocus and find the processing point during detection, thus improving the efficiency of color center processing and detection. It also avoids the possibility of sample contamination when the sample is tested after processing, thereby improving the color center yield.

[0021] 2. The optical device for laser processing and real-time in-situ detection of silicon carbide color centers disclosed in this invention integrates the HBT interferometry (interference test scheme proposed by Hanbury Brown and Twiss) into the processing system, which can determine whether the generated color centers are single-photon sources, making it easier to process high-quality single-photon sources and facilitate integration with quantum devices.

[0022] 3. The optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers disclosed in this invention integrates a fluorescence imaging module and uses an EMCCD to synchronously trigger and acquire fluorescence images under each excitation pulse in real time. This allows for observation of the color center formation process and can intuitively present the shape, size, and distribution of the color centers. This enables a deeper understanding of the factors affecting color center growth, such as the influence of laser processing parameters and material properties on the development of the color center microstructure.

[0023] 4. The optical device for laser processing of silicon carbide color centers and real-time in-situ detection of multiple modes disclosed in this invention uses pulsed laser synchronous EMCCD to acquire fluorescence images under each pulse excitation. Due to the anti-focusing characteristics of photons, the correlation between pixels in the acquired fluorescence images is used to achieve a high-order resolution enhancement effect. Combined with the fluorescence imaging system in the host computer, the captured fluorescence signals can be image processed to improve the fluorescence imaging resolution. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the principle of the optical device for laser processing of silicon carbide color centers and real-time in-situ detection of multiple modes according to the present invention;

[0025] Figure 2 This is an optical path diagram of the optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers according to the present invention.

[0026] Wherein: 1—Femtosecond laser, 2—Half-wave plate, 3—Beam expander, 4—Aperture, 5—Beam splitter, 6—CCD, 7—Flip mirror, 8—Mirror, 9—Scanning galvanometer, 10—Electrically operated stage, 11—Pulsed laser, 12—Dichroic mirror, 13—Filter group, 14—EMCCD, 15—Coupled mirror, 16—Single-mode beam splitter fiber, 17—Photon detector, 18—TCSPC, 19—Spectrometer, 20—Host computer. Detailed Implementation

[0027] The main objective of this invention is to solve the problems of low efficiency and low yield caused by the separation of the processing system and the testing system, as well as the potential contamination caused by sample movement between systems. Furthermore, it aims to improve the detection capabilities for integration with quantum devices and enhance the resolution of fluorescence image observation of the color center formation process. To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0028] In an embodiment, such as Figure 2 As shown in this embodiment, the optical device for real-time in-situ detection of silicon carbide color centers using laser processing is used to realize the processing and multimodal detection of SiC color centers, and can be applied to many key fields such as quantum information technology, high-precision detection, and biological detection. The optical device for real-time in-situ detection of silicon carbide color centers using laser processing in this embodiment includes a femtosecond laser 1, a half-wave plate 2, a beam expander 3, an aperture 4, a beam splitter 5, a CCD 6, a flip mirror 7, a mirror 8, a scanning galvanometer 9, an electric displacement stage 10, a continuous laser 11, a dichroic mirror 12, a filter group 13, an EMCCD 14, a coupling mirror 15, a single-mode beam splitter fiber 16, a photon detector 17, a TCSPC 18, a spectrometer 19, and a host computer 20. The operation of the optical device for real-time in-situ detection of silicon carbide color centers using laser processing is as follows:

[0029] In this implementation case, the processing flow is as follows: The SiC sample is placed in the designated processing area of ​​the electric displacement stage 10, and the Z-axis height of the sample stage is adjusted so that the femtosecond laser can be focused on the surface of the SiC sample. The host computer 20 is connected to the femtosecond laser 1 and controls it to generate a 1030nm femtosecond laser with an average power of 1mW-5W, a repetition rate of 1MHz, and a maximum single pulse energy of 10uJ, generating a suitable femtosecond laser for precise processing of the color center.

[0030] In this implementation case, the laser emitted by the femtosecond laser 1 passes through a half-wave plate 2, a beam expander 3, and an aperture 4 to complete beam expansion and energy adjustment operations, thereby improving the laser quality and making it usable for processing.

[0031] In this implementation, the laser beam used for processing is split into two by beam splitter 5. One part enters CCD 6 for imaging, and the other part enters the subsequent optical path. CCD 6 is connected to host computer 20, which transmits the imaging data back to host computer 20. Host computer 20 processes the imaging data to determine whether the processed laser beam can be used for color center processing, as well as to characterize the sample during processing, and adjusts the parameters of femtosecond laser 1.

[0032] In this implementation example, the processed laser beam can be used for color center processing. It passes directly through the subsequent optical path, and by flipping reflectors 7 and 8, the direction of the optical path is changed, allowing it to enter the scanning galvanometer 9. The scanning galvanometer 9 is connected to the host computer 20. Under the control of the host computer 20, the scanning galvanometer 9 can quickly change the direction of the laser beam, enabling rapid movement of the laser spot in a two-dimensional plane. This precisely positions the laser beam to each point on the workpiece that needs processing, thus completing the processing flow.

[0033] In this implementation case, after the processing is completed, multimodal detection of color centers can be completed without replacing the system, avoiding potential sample contamination from testing the system after processing. The multimodal detection process is as follows: Pulsed laser 11 is connected to host computer 20, and host computer 20 controls various parameters of pulsed laser 11 to output appropriate pulsed laser.

[0034] In this implementation, the pulsed laser 11 outputs a 780nm pulsed laser, which passes through the dichroic mirror 12. Here, the laser undergoes transmission when passing through the dichroic mirror 12. Meanwhile, the flip mirror 7 only participates in the processing during the manufacturing process. During the multi-mode detection process, the flip mirror 7 is electrically controlled to prevent it from participating in the detection optical path.

[0035] In this implementation, the laser light passing through the front optical path passes through the reflector 8, causing the light to be reflected into the scanning galvanometer 9. The scanning galvanometer 9 can precisely control the scanning of the beam to excite fluorescence in the target area. The fluorescence then passes back through the scanning galvanometer 9 and the reflector 8 to reach the dichroic mirror 12. When the fluorescence passes through the dichroic mirror, it is reflected. After passing through the reflector group, it reaches the filter 13. The function of the filter 13 is to remove the laser component from the fluorescence for better subsequent detection.

[0036] In this implementation case, the light beam passing through the filter 13 formally enters the multimodal detection module, which is also connected to the host computer 20. The multimodal detection data can be transmitted to the host computer 20 in real time.

[0037] In this implementation case, the fluorescence entering the multimodal detection module first passes through the beam splitter 5, and a portion enters the EMCCD14. The EMCCD14 is connected to the host computer 20, which can transmit data to the computer in real time. Therefore, the generation of color centers can be observed in real time, which has advantages that other systems do not have.

[0038] In this implementation, another portion of the light is split into two by a beam splitter. One portion of the light is efficiently coupled to the spectrometer 19 through the coupling mirror 15 to detect the fluorescence spectrum. At the same time, the spectrometer 19 is connected to the host computer 20 to transmit the data to the host computer 20 in real time.

[0039] In this implementation, the second portion of light split by the second beam splitter enters the coupling mirror 15, which efficiently couples the light into the single-mode splitting fiber 16. The light is then split into two again, and the single-mode splitting fiber 16 is connected to the photon detector 17. The detector detects the fluorescent signal and generates electrical pulses, which are then sent to the time-correlated single-photon counting card (TCSPC). The TCSPC records the arrival time of each electrical pulse signal in these two paths. Finally, by analyzing the measured time data, the self-correlation information of the photon sequence can be obtained. The second-order correlation function is calculated, and if the value is less than 0.5 color centers, it is considered a single-photon source.

[0040] In the disclosed embodiments, under ideal conditions for all components and with good optical path imaging, the present invention can achieve continuous processing and inspection, all of which are precisely controlled by a computer.

[0041] In the disclosed embodiments, the present invention adjusts the processing parameters in real time, improves the efficiency of color center processing, and enables immediate detection of color center generation and fluorescence imaging after processing.

[0042] In the disclosed embodiments, the present invention is able to detect the formation process of color centers in real time using an EMCCD.

[0043] In the disclosed embodiments, the present invention can perform real-time fluorescence spectroscopy characterization and real-time feedback of single-photon source detection to adjust processing parameters.

[0044] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A silicon carbide color center laser processing and multimodal real-time in-situ detection optical device, characterized in that, The system includes a laser processing system, a confocal laser transmission and spectral detection module, a single-photon source detection module, a fluorescence imaging module, and a data acquisition, processing, and control system. The laser processing system emits a single-pulse laser to process the pre-processed SiC wafer. The SiC wafer is then irradiated with a femtosecond laser to generate defects. The source is switched to excite the defect positions. The material absorbs photon energy and generates electronic transitions. The emitted fluorescence is detected by the confocal laser transmission and spectral detection module and the single-photon source detection module to determine whether color centers are generated and whether the prepared color centers are single-photon sources. The fluorescence imaging module monitors the color center formation process in real time and transmits the acquisition results to the host computer for processing and analysis. The laser processing system is used to process samples with defects. It generates 1030nm pulsed laser through a femtosecond laser, adjusts the polarization state with a half-wave plate, expands the beam with a beam expander, controls the laser energy with an aperture, and achieves precise positioning and processing by working together with a scanning galvanometer and an electric displacement stage. A CCD monitors the surface morphology of the processed surface in real time. The confocal laser transmission and spectral detection module is used to excite defects and perform fluorescence collection and spectral detection. A 780nm laser is generated by a pulsed laser, a short-pass dichroic mirror transmits the laser and reflects the fluorescence, a filter group filters out light outside the fluorescence wavelength, and the light is transmitted to a spectrometer through a coupler and optical fiber for fluorescence spectral characterization, thereby determining whether a color center has been generated. The single-photon source detection module is used to detect whether the color center is a single-photon source. The coupling lens couples the photon sequence into a 50:50 single-mode split fiber, and the fiber is connected to two photon detectors for detection. The electrical pulses generated by the detectors are sent to the time-correlated single-photon counting card (TCSPC). The TCSPC records the arrival time of each electrical pulse signal in the two channels. Finally, by analyzing the measured time data, the self-correlation information of the photon sequence is obtained. The second-order correlation function is calculated. When the value is less than 0.5, it is considered to be a single-photon source. The fluorescence imaging module is used to image the color centers. The EMCCD is synchronously triggered with the pulsed laser to acquire the image sequence of a single color center generated under each pulse excitation and to monitor the formation process of the color centers in real time. The data acquisition, processing, and control system is used to control the laser parameter settings and analyze and process the acquired signals. The host computer controls the operation of each module and is used to realize laser parameter settings, acquisition spectrum and photon sequence signal analysis, real-time monitoring of the fluorescence imaging process, and acquisition image processing.

2. The silicon carbide color center laser processing and multi-modal real-time in-situ detection optical apparatus according to claim 1, wherein, During the processing, the laser processing module dynamically adjusts the power, repetition rate, focus position, and scanning speed of the femtosecond pulse laser according to a preset program or based on real-time sample processing information fed back by the CCD, ensuring the accuracy and stability of color center induction.

3. The optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers according to claim 1, characterized in that, In the confocal laser transmission and spectral detection module, the laser generated by the laser is transmitted to the sample through a dichroic mirror to excite fluorescence. After the fluorescence is reflected by the dichroic mirror, it passes through a filter to remove light outside the fluorescence band, and then enters the spectrometer for detection through a coupling mirror. The confocal optical path ensures that the excitation light and the detection light are confocal, improving the accuracy and resolution of spectral detection.

4. The optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers according to claim 1, characterized in that, During detection, the single-photon source detection module uses a single-mode splitting fiber to precisely split the light into two high-sensitivity photon detectors. The photon detectors convert the photon signals into electrical signals and transmit them to the TCSPC. By transmitting the photon sequence to the host computer, the second-order correlation function of the photons is calculated to determine whether the color center has the characteristics of a single-photon source.

5. The optical device for laser processing and multimodal real-time in-situ detection of silicon carbide color centers according to claim 1, characterized in that, During the imaging process, the fluorescence imaging module synchronously triggers the EMCCD and pulsed laser to continuously acquire fluorescence images under each pulse. Under the control of the imaging parameter adjustment unit, the exposure time and gain are adjusted according to the sample characteristics and imaging requirements. The fluorescence imaging optical path component ensures the stability of the imaging optical path and acquires clear, high-resolution images of silicon carbide color centers. The image data is transmitted to the data acquisition, processing and control module for storage, data processing and analysis.

Images