Transient circular polarization excitation detection microscopic system

Abstract

The utility model provides a transient circular polarization excitation detection microscopic system. The system comprises a femtosecond laser control assembly used for generating laser and controlling a switch of the laser; the first spectroscope is used for dividing the femtosecond laser into two beams of light; the circular polarization pump light adjusting assembly is used for generating circular polarization pump light; the linear polarization detection light adjusting assembly is used for generating linear polarization detection light; the beam combiner is used for combining the circular polarization pump light and the linear polarization detection light; the microscopic imaging assembly is used for carrying out microscopic observation on the sample area and determining a to-be-detected position, and determining that the circular polarization pump light and the linear polarization detection light are accurately irradiated on the to-be-detected position at the same time; the collection detection assembly is used for collecting the linear polarization detection light. According to the utility model, ultrahigh time and space resolution is realized, a micro-area microscopic imaging system is integrated, and the spinning dynamics process of a spinning upward state and a spinning downward state can be observed at the same time.

Description

Technical Field

[0001] The utility model provides a transient circular polarization excitation detection microscopic system, belonging to the technical field of light detection. Background Art

[0002] Femtosecond laser pump-probe technology is an important method for transient absorption detection. By exciting the sample with a beam of high-energy pump light, the carriers will be excited to the excited state. At this time, when another beam of weaker probe light with a wide wavelength range passes through the sample after a certain delay, it will absorb the signal of the probe light. The probe light without pump light excitation will also be absorbed after passing through the sample. Since the pump light excites the carriers to occupy the excited state, the absorption of the probe light changes. Therefore, the different absorption degree of the probe light detection signal before and after the pump light excitation reflects the dynamic process of the carriers, thereby obtaining the dynamic process of the carriers at high time resolution. Femtosecond laser pump-probe technology has high time resolution, which depends on the pulse width of the femtosecond laser. The pump-probe technology is particularly suitable for materials that do not emit light or emit light weakly after stimulated radiation. The dynamic process of carrier generation, relaxation, transmission, and recombination after light excitation can be obtained.

[0003] Spin is an intrinsic property of materials. Using carrier spin to manipulate information is a hot topic in current research. With the development of spin dynamics, many spin-related applications such as spin devices and spin logic gates have emerged. Spin dynamics continues to promote the progress and development of information technology. According to the valley selection rule, after the material is excited by left-handed circularly polarized light, the spin-up electrons will more easily transition to the excited state. At this time, the dynamic behavior of the electrons can be detected using left-handed circularly polarized light. Similarly, the dynamic behavior of the spin-down electrons can be detected using right-handed circularly polarized light. At the same time, in the excited state, the spin direction of some excited state electrons will flip, and relaxation processes of the two spin states of spin-up and spin-down will occur. Summary of the invention

[0004] In view of the above technical problems, the utility model proposes a transient circular polarization excitation detection microscopy system with high time resolution, which integrates microscopic imaging of micro areas and can simultaneously measure the dynamic information of two spin states.

[0005] The utility model provides a transient circular polarization excitation detection microscopy system, which realizes ultra-high time and space resolution, integrates a micro-area microscopic imaging system, and can simultaneously observe the spin dynamics process of the spin-up state and the spin-down state.

[0006] The technical solution proposed by the utility model is:

[0007] A transient circular polarization excitation detection microscopy system, comprising: a femtosecond laser control component, a first beam splitter, a circular polarization pump light adjustment component, a linear polarization detection light adjustment component, a beam combiner, a microscopy imaging component, and a collection detection component;

[0008] The femtosecond laser control component is used to generate laser and control the laser switch;

[0009] Beam splitter No. 1 is used to split the femtosecond laser into two beams;

[0010] The circularly polarized pump light adjustment component is used for generating circularly polarized pump light;

[0011] The linear polarization detection light adjustment component is used to generate linear polarization detection light;

[0012] The beam combiner is used to combine the circularly polarized pump light and the linearly polarized detection light;

[0013] The microscopic imaging component is used to perform microscopic observation of the sample area and determine the position to be measured, and at the same time ensure that the circularly polarized pump light and the linearly polarized detection light are accurately irradiated on the position to be measured;

[0014] The collection and detection component is used to collect linearly polarized detection light.

[0015] Among them, the femtosecond laser control component includes a femtosecond laser and an optical switch in sequence.

[0016] Among them, the circular polarization pump light adjustment component includes a BBO frequency doubling crystal, a No. 1 filter, a delay line, a No. 1 reflector, a No. 1 attenuator, a chopper, a No. 1 linear polarizer, and a No. 1 quarter wave plate in sequence along the optical path;

[0017] The BBO frequency doubling crystal is used to generate high-energy pump light from the light split by the No. 1 beam splitter;

[0018] Filter No. 1 is used to filter out the original laser;

[0019] The delay line is used to adjust the optical path difference between the circularly polarized pump light and the linearly polarized probe light;

[0020] Attenuator No. 1 is used to adjust the intensity of pump light;

[0021] The chopper is used to regulate the pump light pulses;

[0022] Linear polarizer No. 1 is used to generate linearly polarized pump light;

[0023] The first quarter wave plate is used to generate circularly polarized pump light, which is incident on the beam combiner.

[0024] The linear polarization detection light adjustment component includes a second attenuation plate, a pinhole aperture, a first focusing lens, a sapphire, a second focusing lens, a second filter, a second reflector, and a second linear polarizer in sequence along the optical path;

[0025] The second attenuator is used to control the intensity of the incident laser split by the first beam splitter, and to control the incident sapphire laser to produce stable white light detection light;

[0026] The small aperture is used to adjust the laser incident on the sapphire to be uniform and generate stable white light detection light;

[0027] Focusing lens No. 1 is used to focus the laser incident on sapphire;

[0028] Sapphire is used to generate white light probe light;

[0029] The second focusing lens is used to homogenize the generated detection white light;

[0030] Filter No. 2 is used to filter out the original laser;

[0031] The second linear polarizer is used to generate linearly polarized detection light, and the linearly polarized detection light is incident on the beam combiner.

[0032] Among them, the microscopic imaging components include the stage, light-collecting objective lens, No. 2 beam splitter, white light source, and CCD camera;

[0033] The stage is used to place the sample to be tested;

[0034] The light-collecting objective lens is used to focus the linearly polarized detection light and the illuminating white light transmitted through the sample;

[0035] The second beam splitter is used to reflect the irradiation light of the white light source and transmit the imaging light;

[0036] White light sources are used for lighting;

[0037] CCD camera is used for microscopic imaging of micro areas.

[0038] The collection and detection components include a No. 3 reflector, a focusing lens, a No. 4 reflector, a No. 3 filter, a No. 2 quarter wave plate, a Wollaston prism, a No. 1 photodetector, and a No. 2 photodetector;

[0039] The third reflector is used to reflect the circularly polarized pump light and the linearly polarized detection light combined by the beam combiner;

[0040] The condensing objective lens is used to focus the circularly polarized pump light and the linearly polarized detection light;

[0041] Filter No. 3 is used to filter out circularly polarized pump light;

[0042] The second quarter-wave plate is used to convert the collected probe light into linearly polarized light;

[0043] Wollaston prism is used to produce two linearly polarized beams with perpendicular vibration directions;

[0044] Photodetector No. 1 and photodetector No. 2 are used to convert the two optical signals of the Wollaston prism into electrical signals.

[0045] Among them, the computer controls the optical switch, microscopic imaging, and photodetector signal collection and processing.

[0046] The No. 2 beam splitter and the No. 4 reflector are movable mirrors. Before the transient circular polarization excitation detection, the No. 2 beam splitter moves into the light path and the No. 4 reflector moves out of the light path, that is, the microscopic imaging system works to perform microscopic imaging of the sample area to be measured and locate the position to be measured; when the No. 2 beam splitter moves out of the light path and the No. 4 reflector moves into the light path, circular polarization excitation detection is performed on the sample to be measured.

[0047] The technical effects of the utility model are as follows:

[0048] 1. The laser used in the utility model is a titanium-doped sapphire femtosecond laser with a resolution of up to 100fs; at the same time, the integrated micro-area microscopic imaging system can be used for microscopic imaging and precise positioning of the sample area to be tested, so the system has high temporal and spatial resolution.

[0049] 2. The utility model uses a Wollaston prism to split the detection light into two linearly polarized lights in perpendicular directions, and can simultaneously detect two components of light through two photoelectric detectors, that is, simultaneously detect left-handed circularly polarized light and right-handed circularly polarized light, thereby improving system efficiency.

[0050] 3. The pump light is generated by the light source laser through the BBO frequency doubling crystal, and the generation method is simple; the white light detection light is generated by the light source laser through sapphire, and stable white light detection light can be obtained by adjusting the second attenuation plate and the small aperture diaphragm; the circularly polarized pump light and the linearly polarized detection light are combined by a beam combiner, and the optical path adjustment is simple.

[0051] 4. The optical switch, micro-area microscopic imaging and photoelectric detector signal collection and processing involved in the utility model are all controlled by a computer, and the control method is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a schematic diagram of the structure of the utility model:

[0053] Figure 2 It is a schematic diagram of the optical path structure of the utility model. DETAILED DESCRIPTION

[0054] The present invention is further described below with reference to the accompanying drawings and specific examples:

[0055] like Figure 1 As shown, the instantaneous circular polarization excitation detection microscopy system of the utility model comprises: a femtosecond laser control component, a first beam splitter 3, a circular polarization pump light adjustment component, a linear polarization detection light adjustment component, a beam combiner 20, a microscopic imaging component, and a collection detection component;

[0056] Specific as Figure 2 As shown, the femtosecond laser control component is used to generate laser and control the switch of the laser; the femtosecond laser control component includes a femtosecond laser 1 and an optical switch 2; the femtosecond laser 1 generates an incident laser with a central wavelength of 800nm ​​and a frequency of 250Hz, and an output pulse width of 100fs, so one cycle of circular polarization excitation detection is 4ms, and the high time resolution of the device is 100fs; the optical switch 2 is controlled by a computer 34, and the switch is opened during circular polarization excitation detection, and the switch is automatically closed after the end.

[0057] The first beam splitter 3 is used to split the femtosecond laser into two beams.

[0058] The circularly polarized pump light regulating component is used to generate circularly polarized pump light; the circularly polarized pump light regulating component includes a BBO frequency doubling crystal 4, a first filter 5, a delay line 6, a first reflector 7, a first attenuation plate 8, a chopper 9, a first linear polarizer 10, and a first quarter wave plate 11; the BBO frequency doubling crystal 4 doubles the frequency of an 800nm ​​laser to generate a 400nm high-energy pump light; the first filter 5 filters out the 800nm ​​laser; the delay line 6 controls the optical path of the pump light and adjusts the optical path difference between the circularly polarized pump light and the linearly polarized detection light; the first attenuation plate 8 adjusts the intensity of the pump light; the chopper 9 adjusts the frequency of the pump light to 125Hz, thereby generating an alternating excitation signal of the pump light; a single-direction linear polarized light is generated through the first linear polarizer 10; the angle between the first linear polarizer 10 and the first quarter wave plate 11 is adjusted to be positive or negative 45°, and the linear polarized light passes through the first quarter wave plate 11 to generate left-handed circularly polarized light or right-handed circularly polarized light.

[0059] The linear polarization detection light adjustment component is used to generate linear polarization detection light; the linear polarization detection light adjustment component includes a second attenuation plate 12, a pinhole aperture 13, a first focusing lens 14, a sapphire 15, a second focusing lens 16, a second filter 17, a second reflector 18, and a second linear polarizer 19; the second attenuation plate 12 adjusts the 800nm ​​laser intensity, controls the laser incident on the sapphire 15 to generate a stable white light detection light; the pinhole aperture 13 adjusts the 800nm ​​laser uniformity, controls the laser incident on the sapphire 15 to generate a stable white light detection light; a The No. 1 focusing lens 14 focuses the 800nm ​​laser incident on the sapphire 15; the sapphire 15 generates white light detection light; the No. 2 focusing lens 16 homogenizes the generated white light detection light; the No. 2 filter 17 filters out the incident 800nm ​​laser; the detection light passes through the No. 2 linear polarizer 19 to generate linearly polarized light, which is composed of a left-handed circularly polarized light component and a right-handed circularly polarized light component, thereby generating a stable linearly polarized white light detection light, and the detection light wavelength range is 450nm-800nm, so the detection wavelength range is also 450nm-800nm.

[0060] The beam combiner 20 is used to combine the circularly polarized pump light and the linearly polarized detection light.

[0061] The microscopic imaging component is used to perform microscopic observation on the sample area and determine the position to be measured, and at the same time ensure that the circularly polarized pump light and the linearly polarized detection light are accurately irradiated on the position to be measured; the No. 2 beam splitter 25 and the No. 4 reflector 27 are movable mirrors. During microscopic imaging of the micro area, the No. 2 beam splitter 25 moves into the light path, and the No. 4 reflector 27 moves out of the light path. The white light source 26 emits irradiation light, which is reflected by the No. 2 beam splitter 25, passes through the light-collecting objective lens 24 and reaches the stage 23. The reflected imaging light passes through the light-collecting objective lens 24, is transmitted through the No. 2 beam splitter 25 and reaches the CCD camera 28, thereby microscopically imaging the sample to be measured.

[0062] During transient circular polarization excitation detection, the second beam splitter 25 moves out of the light path, and the fourth reflector 27 moves into the light path. The circularly polarized pump light and the linearly polarized detection light pass through the focusing objective lens 22 to reach the stage 23. The transmitted light passes through the light-collecting objective lens 24, is reflected by the fourth reflector 27, and then the 400nm circularly polarized pump light is filtered out by the third filter 29. The left-handed circularly polarized detection light component and the right-handed circularly polarized detection light component pass through the second quarter wave plate 30 to generate linearly polarized light. The linearly polarized light passes through the Wollaston prism 31 to generate two beams of linearly polarized light with perpendicular vibration directions. The two beams of signals are respectively collected by the first photodetector 32 and the second photodetector 33 and converted into electrical signals, which are analyzed and processed by the computer 34.

[0063] Furthermore, the implementation method of the above-mentioned transient circular polarization excitation detection microscopy system includes:

[0064] 1. A femtosecond laser 1 emits laser light, which is transmitted through an optical switch 2 controlled by a computer 34 to a beam splitter 3, which splits the laser light into two beams.

[0065] 2. A beam of light passes through a BBO frequency doubling crystal 4 to generate high-energy pump light; the original laser is filtered out through a filter No. 1 5; the optical path of the pump light is controlled through a delay line 6; the pump light intensity is controlled through an attenuator No. 1 8; the pulse width of the pump light is controlled through a chopper 9; a linearly polarized pump light in a single direction is generated through a linear polarizer No. 10; the angle between the linear polarizer No. 10 and the quarter-wave plate No. 1 11 is adjusted to be plus or minus 45°, and the linearly polarized pump light passes through the quarter-wave plate No. 1 11 to generate a circularly polarized pump light.

[0066] 3. Another beam of light passes through the second attenuation plate 12 and the pinhole diaphragm 13. The second attenuation plate 12 controls the intensity of the laser incident on the sapphire 15 to produce stable white light detection light. The pinhole diaphragm 13 adjusts the incident laser to be uniform and produces stable white light detection light. The laser is focused by the first focusing lens 14. White light detection light is generated by the sapphire 15. The white light detection light is made uniform by the second focusing lens 16. The original laser is filtered out by the second filter 17. The linear polarization detection light is generated by the second linear polarizer 19. The linear polarization detection light consists of two components, the left-handed circularly polarized detection light and the right-handed circularly polarized detection light, thereby generating linear polarized detection white light.

[0067] 4. The beam combiner 20 combines the circularly polarized pump light and the linearly polarized detection light.

[0068] 5. During microscopic imaging, the second beam splitter 25 moves into the light path, and the fourth reflector 27 moves out of the light path. The white light source 26 emits irradiation light, which is reflected by the second beam splitter 25, passes through the light-collecting objective lens 24, and reaches the stage 23. The reflected imaging light passes through the light-collecting objective lens 24, transmits through the second beam splitter 25, and reaches the CCD camera 28, thereby forming a microscopic image of the sample to be measured.

[0069] 6. During transient circular polarization excitation detection, the second beam splitter 25 moves out of the light path, and the fourth reflector 27 moves into the light path. The circularly polarized pump light and the linearly polarized detection light pass through the focusing objective 22 to reach the stage 23. The transmitted light passes through the light-collecting objective 24, is reflected by the fourth reflector 27, and the circularly polarized pump light is filtered out by the third filter 29. The left-handed circularly polarized detection light component and the right-handed circularly polarized detection light component pass through the second quarter wave plate 30 to become linearly polarized light. The linearly polarized light passes through the Wollaston prism 31 to generate two beams of linearly polarized light with perpendicular vibration directions. The two beams of signals are collected by the first photodetector 32 and the second photodetector 33, respectively.

Claims

1. A transient circular polarization excitation detection microscopy system, characterized in that: include: A femtosecond laser control component, a first beam splitter (3), a circularly polarized pump light adjustment component, a linearly polarized detection light adjustment component, a beam combiner (20), a microscopic imaging component, and a collection detection component; The femtosecond laser control component is used to generate laser and control the laser switch; Beam splitter No. 1 (3) is used to split the femtosecond laser into two beams; The circularly polarized pump light adjustment component is used for generating circularly polarized pump light; The linear polarization detection light adjustment component is used to generate linear polarization detection light; The beam combiner (20) is used to combine the circularly polarized pump light and the linearly polarized detection light; The microscopic imaging component is used to perform microscopic observation of the sample area and determine the position to be measured, and at the same time ensure that the circularly polarized pump light and the linearly polarized detection light are accurately irradiated on the position to be measured; The collection and detection component is used to collect linearly polarized detection light.

2. A transient circular polarization excitation detection microscopy system according to claim 1, characterized in that: The femtosecond laser control component comprises a femtosecond laser (1) and an optical switch (2) in sequence.

3. The transient circular polarization excitation detection microscopy system according to claim 1, characterized in that: The circularly polarized pump light adjustment component comprises, along the optical path, a BBO frequency doubling crystal (4), a first filter (5), a delay line (6), a first reflector (7), a first attenuation plate (8), a chopper (9), a first linear polarizer (10), and a first quarter-wave plate (11); The BBO frequency doubling crystal (4) is used to generate high-energy pump light from the light split by the first beam splitter (3); Filter No. 1 (5) is used to filter out the original laser light; The delay line (6) is used to adjust the optical path difference between the circularly polarized pump light and the linearly polarized probe light; The first attenuator (8) is used to adjust the intensity of the pump light; The chopper (9) is used to adjust the pump light pulse; A first linear polarizer (10) is used to generate linearly polarized pump light; The first quarter wave plate (11) is used to generate circularly polarized pump light, and the circularly polarized pump light is incident on the beam combining mirror (20).

4. The transient circular polarization excitation detection microscopy system according to claim 1, characterized in that: The linear polarization detection light adjustment component comprises, along the optical path, a second attenuation plate (12), a pinhole aperture (13), a first focusing lens (14), a sapphire (15), a second focusing lens (16), a second filter (17), a second reflector (18), and a second linear polarizer (19); The second attenuation plate (12) is used to control the intensity of the incident laser beam split by the first beam splitter (3), and to control the laser beam incident on the sapphire (15) to generate stable white light detection light; The pinhole aperture (13) is used to adjust the laser light incident on the sapphire (15) to be uniform, thereby generating stable white light detection light; The first focusing lens (14) is used to focus the laser light incident on the sapphire (15); Sapphire (15) is used to generate white light probe light; The second focusing lens (16) is used to homogenize the generated detection white light; The second filter (17) is used to filter out the original laser light; The second linear polarizing plate (19) is used to generate linearly polarized detection light, and the linearly polarized detection light is incident on the beam combining mirror (20).

5. The transient circular polarization excitation detection microscopy system according to claim 1, characterized in that: The microscopic imaging assembly comprises a stage (23), a light-collecting objective lens (24), a second beam splitter (25), a white light source (26), and a CCD camera (28); The stage (23) is used to place the sample to be tested; The light-collecting objective lens (24) is used for focusing the linearly polarized detection light and the illuminating white light transmitted through the sample; The second beam splitter (25) is used to reflect the illumination light of the white light source and transmit the imaging light; the second beam splitter (25) is a movable mirror; A white light source (26) is used for illumination; The CCD camera (28) is used for microscopic imaging of micro areas.

6. The transient circular polarization excitation detection microscopy system according to claim 1, characterized in that: The collecting and detecting assembly comprises a third reflector (21), a focusing lens (22), a fourth reflector (27), a third filter (29), a second quarter wave plate (30), a Wollaston prism (31), a first photodetector (32), and a second photodetector (33); The third reflector (21) is used to reflect the circularly polarized pump light and the linearly polarized detection light combined by the beam combining mirror (20); The focusing objective lens (22) is used to focus the circularly polarized pump light and the linearly polarized detection light; The fourth reflector (27) is a movable mirror; The third filter (29) is used to filter out the circularly polarized pump light; The second quarter wave plate (30) is used to convert the collected detection light into linearly polarized light; The Wollaston prism (31) is used to generate two linearly polarized light beams with perpendicular vibration directions; The first photodetector (32) and the second photodetector (33) are used to convert the two optical signals of the Wollaston prism (31) into electrical signals; The computer (34) controls the optical switch (2), microscopic imaging, and photodetector signal collection and processing.

Images