Micro-area femtosecond transient absorption detection system

Abstract

The utility model provides a micro-area femtosecond transient absorption detection system. A femtosecond laser light source control assembly is used for generating laser; the first spectroscope is used for dividing the femtosecond laser into two beams of light; the pump light adjusting assembly is used for generating pump light and adjusting intensity and frequency; the detection light adjusting assembly is used for generating detection light and adjusting the intensity of the detection light to be proper and stable; the beam combiner is used for combining the pump light and the detection light; the transmission absorption detection assembly is used for irradiating a sample with the pump light and the detection light and generating detection transmission light; the reflection absorption detection assembly is used for irradiating the pump light and the detection light to a sample and generating detection reflected 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 pump light and the probe light are accurately irradiated on the to-be-detected position; the detection assembly is used for collecting detection light. According to the utility model, ultrahigh space and time resolution is realized, and functions of transmission transient absorption detection, reflection transient absorption detection and micro-area microscopic imaging are integrated.

Description

Technical Field

[0001] The utility model provides a micro-area femtosecond transient absorption detection system, belonging to the technical field of light detection. Background Art

[0002] With the development of femtosecond lasers, the exploration of ultrafast processes in matter has entered the femtosecond time domain. Ultrafast spectroscopy technology based on femtosecond lasers has become a powerful tool for studying and detecting various ultrafast dynamics.

[0003] With the rapid development of optoelectronics, the process of light-matter interaction, such as carrier generation, migration and recombination, is related to the excited state of the material, so it is crucial to detect and understand the excited state properties of the material. Transient absorption spectroscopy can provide information on the carrier excitation and relaxation process. Compared with steady-state absorption spectroscopy, transient absorption spectroscopy has high time resolution and can explore the light-matter interaction process in materials on a very short time scale. It can provide dynamic information in the material after light excitation, including carrier generation, transport and recombination processes. At the same time, it can also explore the optical properties of materials in non-equilibrium states, thereby studying the optical response and dynamic processes of materials.

[0004] Femtosecond pump-probe technology is an ultrafast spectroscopy technology that detects the time-varying number of particles in the excited state energy level of the sample being tested after being excited by a femtosecond pulse laser. The femtosecond pulse laser light source is split into pump light and probe light. The higher-energy pump light is focused onto the sample to excite the sample to an excited state. The probe light also passes through the area excited by the pump light. Different probe light signals are detected due to the different degrees of absorption of the probe light by the material before and after excitation. The time difference between the pump light and the probe light reaching the sample is changed by a delay line, thereby detecting the excited state signals at different times, i.e., the kinetic process.

[0005] To fully detect the dynamic process of materials, a femtosecond transient absorption detection system with high time and space resolution is required. However, in practical applications, micro-area pump-probe systems often encounter the following difficulties: 1. The problem of combining the pump light and the probe light. The coincidence of the two beams of light in space is affected by the laser angle and the dispersion of the objective lens, so it is difficult to overlap the two beams of light. 2. The problem of high spatial resolution microscopic imaging of the sample area. The micro-area femtosecond transient absorption spectrum requires precise detection of the sample area. 3. For opaque substrates, a reflection transient absorption detection method needs to be used.

[0006] Existing femtosecond pump-probe devices, such as Figure 1As shown, a femtosecond laser (101) emits laser light, which is split into two beams by a beam splitter (102); one beam of light passes through an optical parametric amplifier (103) to adjust the frequency to obtain high-energy pump light, which passes through a reflector (104) and then is adjusted by a chopper (1010) to generate excitation light of an alternating signal, so that detection light signals when the pump light is excited and when the pump light is not excited can be collected; the other beam of light passes through an optical parametric amplifier (106) to generate detection light of a specific wavelength, which is reflected by a reflector (107) and then is The optical path difference between the detection light and the pump light is controlled by the delay line (108), and then the pump light and the detection light are combined by the beam combiner (109), thereby generating pulsed pump light and single wavelength detection light; the two beams of light are reflected by the reflector (1010), focused by the focusing objective lens (1011), and then irradiated onto the sample on the sample stage (1012); the transmitted light is finally filtered out of the pump light by the filter (1013), and the transmitted detection light signal is collected by the spectrometer (1014), thereby reflecting the dynamic information of the sample material after the pump light is excited. The device has the following disadvantages:

[0007] 1. The choice of substrate for the sample to be tested is limited, and only transparent substrates that can transmit light can be selected.

[0008] 2. Pump light and detection light are generated by an optical parametric amplifier. The wavelength of the detection light signal collected each time is single and the cost is high.

[0009] 3. It cannot guarantee that the pump light and the detection light are completely combined and accurately irradiated on the sample area to be tested. Utility Model Content

[0010] In view of the above technical problems, the utility model provides a micro-area femtosecond transient absorption detection system to solve the following technical problems:

[0011] 1. Improve the selectivity of the sample substrate to be tested by adding a reflection detection component.

[0012] 2. Use frequency doubling crystals to generate high-energy pump light to reduce costs, and use sapphire to generate white light detection light to increase the detection wavelength range.

[0013] 3. By adding a microscopic imaging component, it is ensured that the pump light and the detection light are completely combined and the two beams of light are accurately irradiated on the area to be tested on the sample.

[0014] The utility model provides a micro-area femtosecond transient absorption detection system, which achieves ultra-high spatial and temporal resolution and integrates a transmission transient absorption detection system, a reflection transient absorption detection system and a micro-area microscopic imaging system.

[0015] The technical solution proposed by the utility model is:

[0016] A micro-area femtosecond transient absorption detection system, comprising: a femtosecond laser light source control component, a first beam splitter, a pump light adjustment component, a detection light adjustment component, a beam combiner, a transmission absorption detection component, a reflection absorption detection component, a microscopic imaging component, and a detection component;

[0017] The femtosecond laser light source control component is used to generate laser and control the laser switch;

[0018] Beam splitter No. 1 is used to split the femtosecond laser into two beams;

[0019] The pump light regulating component is used to generate pump light and regulate the pump light to a proper intensity and frequency;

[0020] The detection light adjustment component is used to generate detection light and adjust the detection light to a proper intensity and stability;

[0021] The beam combiner is used to combine the pump light and the detection light;

[0022] The transmission absorption detection component is used for irradiating the pump light and the detection light onto the sample and generating the detection transmission light;

[0023] The reflection absorption detection component is used for irradiating the pump light and the detection light onto the sample and generating the detection reflection light;

[0024] The microscopic imaging component is used to microscopically observe the sample area and determine the position to be measured, and at the same time ensure that the pump light and the detection light are accurately irradiated on the position to be measured;

[0025] The detection component is used to collect the detection light.

[0026] Among them, the femtosecond laser light source control component includes a femtosecond laser and an optical switch.

[0027] Among them, the pump light adjustment components include BBO frequency doubling crystal, No. 1 filter, delay line, No. 1 reflector, No. 1 attenuator, and chopper;

[0028] BBO frequency doubling crystal is used to double the frequency of incident laser to generate high-energy pump light;

[0029] Filter No. 1 is used to filter out the original laser;

[0030] The delay line is used to control the optical path and adjust the optical path difference between the pump light and the detection light;

[0031] Attenuator No. 1 is used to adjust the intensity of pump light;

[0032] A chopper is used to condition the pump light pulses.

[0033] The detection light adjustment component includes a No. 2 attenuation plate, a pinhole aperture, a No. 1 focusing lens, a sapphire, a No. 2 focusing lens, a No. 2 reflecting mirror, and a No. 2 filter;

[0034] The second attenuation plate is used to control the intensity of the incident laser and control the laser incident on the sapphire to produce stable white light;

[0035] The small aperture is used to adjust the laser incident on the sapphire to be uniform and produce stable white light;

[0036] Focusing lens No. 1 is used to focus the laser incident on sapphire;

[0037] Sapphire is used to generate white light probe light;

[0038] The second focusing lens is used to homogenize the generated detection white light;

[0039] Filter No. 2 is used to filter out the original laser.

[0040] Among them, the transmission absorption detection component includes a No. 3 reflector, a No. 1 focusing lens, and a stage.

[0041] Among them, the reflection absorption detection component includes a No. 4 reflector, a No. 5 reflector, a No. 2 beam splitter, a No. 2 focusing objective lens, and a stage.

[0042] Among them, the microscopic imaging components include a No. 3 spectroscope, a white light source, and a CCD camera.

[0043] Among them, the detection components include No. 6 reflector, No. 3 filter, and spectrometer;

[0044] Filter No. 3 is used to filter out the pump light.

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

[0046] Before pump-detection, the No. 3 beam splitter moves into the optical path, and the No. 6 reflector moves out of the optical path, that is, the microscopic imaging system works to perform microscopic imaging on the sample area to be tested and locate the position to be tested; when the No. 4 reflector, the No. 5 reflector, the No. 2 beam splitter, and the No. 3 beam splitter move out of the optical path, and the No. 6 reflector moves into the optical path, that is, the transmission absorption detection component moves into the optical path, pump-detection can be performed on the transparent substrate sample to be tested; when the No. 4 reflector, the No. 5 reflector, the No. 2 beam splitter, and the No. 6 reflector move into the optical path, and the No. 3 beam splitter moves out of the optical path, that is, the reflection absorption detection component moves into the optical path, pump-detection can be performed on the opaque substrate sample to be tested.

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

[0048] 1. The microscopic imaging component can ensure the complete beam combination of pump light and detection light, as well as microscopic imaging and precise positioning of the sample area to be tested, which facilitates signal search and detection and improves experimental efficiency.

[0049] 2. The integrated transmission absorption detection system and reflection absorption detection system improve the substrate selectivity and can perform pump-detection on transparent and opaque substrates.

[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; the pump light and the detection light are combined by a beam combiner, and the optical path adjustment is simple.

[0051] 4. The optical switch, microscopic imaging component and optical detection component 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 It is a structural schematic diagram of the prior art;

[0053] Figure 2 It is a structural schematic diagram of the utility model;

[0054] Figure 3 It is a schematic diagram of the optical path of the utility model. DETAILED DESCRIPTION

[0055] The present invention is further described below with reference to the accompanying drawings and specific examples:

[0056] like Figure 2 As shown, the micro-area femtosecond transient absorption detection system of the utility model includes: a femtosecond laser light source control component, a first beam splitter 3, a pump light adjustment component, a detection light adjustment component, a beam combiner 17, a transmission absorption detection component, a reflection absorption detection component, a microscopic imaging component, and a detection component;

[0057] Specific as Figure 3 As shown, the femtosecond laser light source control component is used to generate laser and control the switch of the laser; the femtosecond laser light source 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 a pump-detection cycle is 4ms, and the high time resolution of the device is 100fs; the optical switch 2 is controlled by a computer 31, and the switch is opened during pump-detection, and the switch is closed after the end.

[0058] The beam splitter No. 1 3 is used to split the femtosecond laser into two beams.

[0059] The pump light regulating component is used to generate pump light and regulate the pump light to proper intensity and frequency; the pump light regulating component comprises a BBO frequency doubling crystal 4, a No. 1 filter 5, a delay line 6, a No. 1 reflector 7, a No. 1 attenuation plate 8, and a chopper 9; the BBO frequency doubling crystal 4 doubles the frequency of 800nm ​​laser to generate 400nm high-energy pump light; the No. 1 filter 5 filters out the 800nm ​​laser; the delay line 6 controls the optical path of the pump light and regulates the optical path difference between the pump light and the detection light; the No. 1 attenuation plate 8 regulates the intensity of the pump light; the chopper 9 regulates the frequency of the pump light to 125Hz, thereby generating an alternating excitation signal of the pump light.

[0060] The detection light adjustment component is used to generate detection light and adjust the detection light to appropriate intensity and stability; the detection light adjustment component includes a second attenuation plate 10, a pinhole aperture 11, a first focusing lens 12, a sapphire 13, a second focusing lens 14, a second reflector 15, and a second filter 16; the second attenuation plate 10 adjusts the intensity of the 800nm ​​laser and controls the laser incident on the sapphire 13 to generate a stable white light detection light; the pinhole aperture 11 adjusts the uniformity of the 800nm ​​laser and controls the uniformity of the laser incident on the sapphire 13 to generate a stable white light detection light; the first focusing lens 12 focuses the 800nm ​​laser incident on the sapphire 13; the sapphire 13 generates white light detection light; the second focusing lens 14 uniformizes the generated white light detection light; the second filter 16 filters out the incident 800nm ​​laser, thereby generating a stable white light detection light, and the wavelength range of the white light detection light is 450nm-800nm, so the detection wavelength range is also 450nm-800nm.

[0061] The beam combiner 17 is used to combine the pump light and the detection light.

[0062] 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 pump light and the detection light are accurately irradiated on the position to be measured; before pump-detection, the No. 3 beam splitter 25 moves into the light path, and the No. 6 reflector 28 moves out of the light path. The white light source 26 emits irradiation light, which is reflected by the No. 3 beam splitter 25, passes through the No. 2 focusing objective lens 24 and reaches the stage 23. The reflected imaging light passes through the No. 2 focusing objective lens 24, transmits through the No. 3 beam splitter 25 and reaches the CCD camera 27, thereby microscopically imaging the sample to be measured.

[0063] The transmission absorption detection component is used to irradiate the pump light and the detection light onto the sample and generate the detection transmission light; the reflection absorption detection component is used to irradiate the pump light and the detection light onto the sample and generate the detection reflection light; during transmission absorption detection, the fourth reflector 18, the fifth reflector 19, the second beam splitter 20, and the third beam splitter 25 are moved out of the light path, and the sixth reflector 28 is moved into the light path. The pump light and the detection light pass through the first focusing objective lens 22 to reach the stage 23. The transmission light passes through the second focusing objective lens 24 and is reflected by the sixth reflector 28. The 400nm pump light is filtered out by the No. 3 filter 29, and the transmitted detection light is finally collected by the spectrometer 30; during reflection absorption detection, the No. 4 reflector 18, the No. 5 reflector 19, the No. 2 beam splitter 20, and the beam splitter 28 are moved into the light path, and the No. 3 beam splitter 25 is moved out of the light path, and the pump light and the detection light pass through the focusing objective lens 24 to reach the stage 23, and the reflected light passes through the No. 2 focusing objective lens 24, and after being reflected by the No. 6 reflector 28, the 400nm pump light is filtered out by the No. 3 filter 29, and finally the reflected detection light is collected by the spectrometer 30.

[0064] The method for realizing the micro-area femtosecond transient absorption detection system comprises:

[0065] 1. The laser emitted by the femtosecond laser 1 passes through the optical switch 2 controlled by the computer 31 and reaches the first beam splitter 3, which splits the laser into two beams.

[0066] 2. A beam of light passes through the BBO frequency doubling crystal 4 to generate high-energy pump light; the original laser is filtered out through the No. 1 filter 5; the optical path of the pump light is controlled by the delay line 6; the pump light intensity is controlled by the No. 1 attenuator 8; the pump light pulse width is controlled by the chopper 9, thereby generating pump light with a specific pulse width and appropriate intensity.

[0067] 3. Another beam of light passes through the second attenuation plate 10 and the pinhole diaphragm 11. The second attenuation plate 10 controls the intensity of the incident sapphire laser to produce stable white light detection light. The pinhole diaphragm 11 adjusts the incident laser to be uniform and produces stable white light detection light. The laser is focused by the first focusing lens 12. White light detection light is generated by the sapphire 13. The white light detection light is made uniform by the second focusing lens 14. The original laser is filtered out by the second filter 16, thereby generating stable and appropriately intense detection white light.

[0068] 4. The beam combiner 17 combines the pump light and the detection light.

[0069] 5. During microscopic imaging, the No. 3 beam splitter 25 moves into the light path, and the No. 6 reflector 28 moves out of the light path. The white light source 26 emits irradiation light, which is reflected by the No. 3 beam splitter 25, passes through the No. 2 focusing objective lens 24, and reaches the stage 23. The reflected imaging light passes through the No. 2 focusing objective lens 24, transmits through the No. 3 beam splitter 25, and reaches the CCD camera 27, thereby forming a microscopic image of the sample to be tested.

[0070] 6. During transmission absorption detection, the fourth reflector 18, the fifth reflector 19, the second beam splitter 20, and the third beam splitter 25 move out of the light path, and the sixth reflector 28 moves into the light path. The pump light and the detection light pass through the first focusing objective lens 22 to reach the stage 23. The transmitted light passes through the second focusing objective lens 24, is reflected by the sixth reflector 28, and the pump light is filtered out by the third filter 29. Finally, the spectrometer 30 collects the detection light.

[0071] 7. During reflection absorption detection, the fourth reflector 18, the fifth reflector 19, the second beam splitter 20, and the sixth reflector 28 move into the optical path, and the third beam splitter 25 moves out of the optical path. The pump light and the detection light pass through the focusing objective lens 24 to reach the stage 23. The reflected light passes through the second focusing objective lens 24, is reflected by the sixth reflector 28, and then the pump light is filtered out by the third filter 29. Finally, the spectrometer absorbs the detection light.

[0072] The micro-area femtosecond transient absorption detection system splits the femtosecond pulse laser into pump light and probe light. The higher-energy pump light excites the sample, and the material absorbs the probe light to different degrees before and after excitation, thereby detecting different probe light signals. The optical path difference between the pump light and the probe light is changed by the delay line, thereby detecting the excited state signals at different times, that is, the kinetic process.

Claims

1. A micro-area femtosecond transient absorption detection system, characterized in that: include: A femtosecond laser light source control component, a first beam splitter (3), a pump light adjustment component, a detection light adjustment component, a beam combiner (17), a transmission absorption detection component, a reflection absorption detection component, a microscopic imaging component, and a detection component; The femtosecond laser light source control component is used to generate laser and control the laser switch; A beam splitter No. 1 (3) is used to split the femtosecond laser into two beams; The pump light regulating component is used to generate pump light and regulate the pump light to a proper intensity and frequency; The detection light adjustment component is used to generate detection light and adjust the detection light to appropriate intensity and stability; The beam combining mirror (17) is used to combine the pump light and the detection light; The transmission absorption detection component is used for irradiating the pump light and the detection light onto the sample and generating the detection transmission light; The reflection absorption detection component is used for irradiating the pump light and the detection light onto the sample and generating the detection reflection light; The microscopic imaging component is used to microscopically observe the sample area and determine the position to be measured, and at the same time ensure that the pump light and the detection light are accurately irradiated on the position to be measured; The detection component is used to collect the detection light.

2. A micro-area femtosecond transient absorption detection system according to claim 1, characterized in that: The femtosecond laser light source control component comprises a femtosecond laser (1) and an optical switch (2).

3. The micro-area femtosecond transient absorption detection system according to claim 1, characterized in that: The pump light adjustment component comprises a BBO frequency doubling crystal (4), a first filter (5), a delay line (6), a first reflector (7), a first attenuation plate (8), and a chopper (9); The BBO frequency doubling crystal (4) is used to double the frequency of the incident laser to generate high-energy pump light; Filter No. 1 (5) is used to filter out the original laser light; The delay line (6) is used to control the optical path and adjust the optical path difference between the pump light and the detection light; The first attenuation plate (8) is used to adjust the intensity of the pump light; The chopper (9) is used to adjust the pump light pulses.

4. The micro-area femtosecond transient absorption detection system according to claim 1, characterized in that: The detection light adjustment component comprises a second attenuation plate (10), a pinhole aperture (11), a first focusing lens (12), a sapphire (13), a second focusing lens (14), a second reflecting mirror (15), and a second filter (16); The second attenuation plate (10) is used to control the intensity of the incident laser, and control the laser incident on the sapphire to produce stable white light; The pinhole aperture (11) is used to adjust the laser light incident on the sapphire to be uniform and generate stable white light; A focusing lens (12) is used to focus the laser light incident on the sapphire. Sapphire (13) is used to generate white light detection light; The second focusing lens (14) is used to homogenize the generated detection white light; The second filter (16) is used to filter out the original laser light; The transmission absorption detection assembly includes a third reflector (21), a first focusing lens (22), and an object stage (23); The reflection absorption detection component comprises a fourth reflection mirror (18), a fifth reflection mirror (19), a second beam splitter (20), a second focusing objective lens (24), and an object stage (23).

5. The micro-area femtosecond transient absorption detection system according to claim 1, characterized in that: The microscopic imaging component comprises a third beam splitter (25), a white light source (26), and a CCD camera (27).

6. The micro-area femtosecond transient absorption detection system according to claim 1, characterized in that: The detection assembly comprises a sixth reflector (28), a third filter (29), and a spectrometer (30); The third filter (29) is used to filter out the pump light; The computer (31) controls the optical switch (2), microscopic imaging, and detection light signal collection and processing.

Images