Optical fiber SRS type nonlinear multi-mode miniature beam splitting and combining device and method

Abstract

The invention discloses an optical fiber SRS type nonlinear multi-mode miniature beam splitting and combining device and method. The device comprises a nonlinear excitation light unit, a first long-pass dichroscope, an input and output coupling unit, a primary beam splitting unit, a second reflector, a secondary beam splitting unit, a conversion unit, a fourth long-pass dichroscope and an optical fiber probe. The P polarization femtosecond nonlinear excitation light pulse and the two beams of S polarization picosecond nonlinear excitation light pulses are combined to generate a nonlinear excitation light pulse; the nonlinear excitation light pulse is output, the returned SHG signal light and TPEF signal light are received, and the SHG signal light and the TPEF signal light are collimated, emitted and returned; primary beam splitting is carried out, and nonlinear excitation light pulses and emergent and returned SHG and TPEF signal light are separated; separating stray light and turning the SRS signal light which is transmitted forwards; secondary beam splitting is carried out, and SHG signal light and turning TPEF signal light are separated; the SRS signal light, the SHG signal light and the TPEF signal light are converted into electric signals. By optimizing the structural design, the size of the device is remarkably reduced, and the spectral band range is effectively widened.

Description

Technical Field

[0001] The present invention belongs to the field of fiber optic multimodal nonlinear spectroscopic microscopy, and particularly relates to a fiber optic SRS-type nonlinear multimodal micro beam splitting and combining device and method applicable to a wide wavelength band and dual probes. Background Art

[0002] SRS (stimulated Raman scattering) microscopy technology utilizes the interaction between pump light, Stokes light, and the vibrational energy levels of sample molecules; when the interaction between the electron cloud of the sample, pump light photons, and Stokes light photons generates an induced dipole moment within the sample molecules according to the sample molecular polarizability, it will result in pump energy loss (stimulated Raman loss, SRL) and Stokes energy increase (stimulated Raman gain, SRG). Therefore, stimulated Raman scattering signals can be obtained from SRL or SRG, thereby obtaining high-fidelity Raman spectra unaffected by non-resonant backgrounds. SHG (second-harmonic generation) microscopy technology utilizes the second-order nonlinear polarizability χ of the sample to be measured. (2) To achieve the interaction between light and matter, incident light with a frequency of ω generates a second-harmonic signal with a frequency of 2ω after passing through the sample to be measured. The second-order nonlinear polarizability χ (2) requires a non-centrosymmetric structure, so it can achieve imaging of biological tissues with non-centrosymmetric structures, such as collagen fibers and muscle fibers. TPEF (two-photon excitation fluorescence) microscopy technology utilizes the two-photon absorption transition effect of the sample molecules to be measured. Under the action of an ultrashort pulsed laser, after two photons are simultaneously absorbed and transition to a higher electronic excited state, they relax back to the ground state and emit fluorescence with a wavelength shorter than that of the incident light. The complementarity of the three nonlinear optical spectroscopic imaging technologies of SRS, SHG, and TPEF in terms of chemical specificity, structural sensitivity, and dynamic observation ability is very suitable for constructing an SRS-type nonlinear multimodal imaging system integrating SRS, SHG, and TPEF.

[0003] In traditional SRS-type nonlinear multimodal microscopy systems, the beam splitting and combining device mostly adopts a single working wavelength and a single probe structure, resulting in limited spectral compatibility and difficulty in synchronously capturing and decoupling and analyzing wide-spectrum multimodal optical information. Moreover, the beam splitting and combining device mainly uses large-sized optical elements assembled on a traditional optical platform structure, resulting in an overly large device volume, low anti-interference ability and long-term stability of the device, and high operation and maintenance costs, and it cannot be formed into a portable instrument for clinical applications. Summary of the Invention

[0004] In order to overcome the problems existing in the existing devices and methods, the present invention aims to propose a fiber-optic SRS-type nonlinear multimodal micro beam splitting and combining device and method, which realizes fiber-optic SRS-type nonlinear multimodal micro beam splitting and combining by using the forward excitation principle, and at the same time adapts to two types of fiber-optic probes, namely, a fiber-optic piezoelectric cylinder scanning probe and a fiber-optic MEMS scanning probe.

[0005] In a first aspect, the present invention proposes a fiber-optic SRS-type nonlinear multimodal micro beam splitting and combining device, which includes a nonlinear excitation light unit, a first long-pass dichroic mirror, an input / output coupling unit, a primary beam splitting unit, a second reflector, a secondary beam splitting unit, a conversion unit, a fourth long-pass dichroic mirror, and a fiber-optic probe;

[0006] The nonlinear excitation light unit accesses a P-polarized femtosecond nonlinear excitation light pulse and two S-polarized picosecond nonlinear excitation light pulses, and combines them through the first long-pass dichroic mirror to generate a nonlinear excitation light pulse. The input / output coupling unit includes a fiber-optic input / output coupler and an input / output hollow anti-resonant fiber. The nonlinear excitation light pulse is coupled into the air core of the input / output hollow anti-resonant fiber through the fiber-optic input / output coupler, and the nonlinear excitation light pulse is output to the fiber-optic probe. The fiber-optic probe collects three signal lights from the sample, including SRS signal light, SHG signal light, and TPEF signal light. The input / output hollow anti-resonant fiber is connected to the fiber-optic input / output coupler, and the SHG and TPEF signal lights returned by the fiber-optic probe are received through the cladding of the input / output hollow anti-resonant fiber, and are collimated and emitted through the fiber-optic input / output coupler and returned to the primary beam splitting unit. The primary beam splitting unit includes a second long-pass dichroic mirror, which separates the nonlinear excitation light pulse, the SHG signal light, and the TPEF signal light. The fourth long-pass dichroic mirror separates stray light and turns the forward-transmitted SRS signal light. The secondary beam splitting unit separates the SRS signal light. The conversion unit converts the SRS signal light, the SHG signal light, and the TPEF signal light into electrical signals.

[0007] In some embodiments, the nonlinear excitation light unit includes two input single-mode polarization-maintaining fibers respectively accessing a beam of S-polarized picosecond nonlinear excitation light pulse and one input hollow anti-resonant fiber accessing a beam of P-polarized femtosecond nonlinear excitation light pulse. The fiber-optic input collimation unit includes a fiber-optic input collimator. The two beams of S-polarized picosecond nonlinear excitation light pulses and one beam of P-polarized femtosecond nonlinear excitation light pulse are respectively collimated and emitted through the fiber-optic input collimator. The P-polarized femtosecond nonlinear excitation light pulse is turned by the first reflector and combined with the two beams of S-polarized picosecond nonlinear excitation light pulses through the first long-pass dichroic mirror to obtain a nonlinear excitation light pulse.

[0008] In some embodiments, the first input single-mode polarization-maintaining fiber is connected to a dual-output dual-wavelength picosecond laser to receive an S-polarized picosecond nonlinear excitation optical pulse with a wavelength of 1015 - 1070 nm and a pulse width of 1 ps to 20 ps; the second input single-mode polarization-maintaining fiber is connected to the dual-output dual-wavelength picosecond laser to receive an S-polarized picosecond nonlinear excitation optical pulse with a wavelength of 740 - 862 nm and a pulse width of 1 ps to 20 ps; the first input hollow anti-resonant fiber is connected to a femtosecond laser to receive a P-polarized femtosecond nonlinear excitation optical pulse with a wavelength of 780 nm and a pulse width of 80 fs to 200 fs.

[0009] In some embodiments, the secondary beam splitting unit includes a third long-pass dichroic mirror and a second reflector. The third long-pass dichroic mirror separates the SHG signal light, and the second reflector deflects the TPEF signal light.

[0010] In some embodiments, the conversion unit includes three single-photon detectors, which convert the SRS signal light, SHG signal light, and TPEF signal light into electrical signals in three paths.

[0011] In some embodiments, the fourth long-pass dichroic mirror deflects the SRS signal light through displacement control.

[0012] In some embodiments, the fiber probe adopts a fiber piezoelectric cylinder scanning probe mode or a fiber MEMS scanning probe mode.

[0013] In some embodiments, in the fiber piezoelectric cylinder scanning probe mode, the input-output coupling unit includes two fiber input-output couplers and an input-output hollow anti-resonant fiber combined into one suspended fiber input-output coupler and an input-output hollow anti-resonant fiber. The position of the second long-pass dichroic mirror is controlled to change the SHG signal light and TPEF signal light reflected back to this path of the fiber input-output coupler.

[0014] In some embodiments, in the fiber MEMS scanning probe mode, the input-output coupling unit includes three fiber input-output couplers and an input-output hollow anti-resonant fiber. The position of the second long-pass dichroic mirror is controlled to change the SHG signal light and TPEF signal light reflected back to one path of the fiber input-output coupler connected to the output end of the fiber MEMS scanning probe.

[0015] In a second aspect, the present invention proposes a fiber SRS-type nonlinear multimodal beam splitting and combining method implemented by using a fiber SRS-type nonlinear multimodal beam splitting and combining device, and the method includes the following steps:

[0016] S1. Access a P-polarized femtosecond nonlinear excitation optical pulse and two S-polarized picosecond nonlinear excitation optical pulses, combine them through a first long-pass dichroic mirror to generate a nonlinear excitation optical pulse;

[0017] S2. Output the nonlinear excitation optical pulse, receive the returned SRS signal light, SHG signal light, and TPEF signal light, and collimate and output them for return;

[0018] S3. Perform a first beam splitting to separate the nonlinear excitation optical pulse and the returned SHG signal light and TPEF signal light that are output;

[0019] S3. Separate stray light and deflect the forward-propagating SRS signal light;

[0020] S4. Perform a second beam splitting to separate the SHG signal light and deflect the TPEF signal light;

[0021] S5. Convert the SRS signal light, SHG signal light, and TPEF signal light into electrical signals.

[0022] Compared with existing devices, the beneficial technical effects that can be achieved by the present invention are as follows:

[0023] This device is applicable to wide-band dual probes, uses smaller-sized micro-optical elements with an optical glass plate as the substrate, and is built into a fiber SRS-type nonlinear multimodal micro beam splitting and combining device using a high-precision micro-assembly process. Using single-mode polarization-maintaining fiber and hollow anti-resonant fiber as beam input and output replaces the traditional large-scale spatial optical path system, improving the system stability; using single-mode polarization-maintaining fiber and hollow anti-resonant fiber as beam input and output replaces the traditional large-scale spatial optical path system, improving the system stability; and it can be adapted to fiber piezoelectric cylinder scanning probes and fiber MEMS scanning probes, improving the imaging ability of the SRS-type nonlinear multimodal microscopy system and ensuring portability. Description of the Drawings

[0024] Figure 1 Structural schematic of the fiber SRS-type nonlinear multimodal micro beam splitting and combining device of the present invention Figure 1 ;

[0025] Figure 2 Structural schematic of the fiber SRS-type nonlinear multimodal micro beam splitting and combining device of the present invention Figure 2 ;

[0026] Figure 3 Connection schematic of the fiber SRS-type nonlinear multimodal micro beam splitting and combining device of the present invention with a laser and a scanning probe Figure 1 ;

[0027] Figure 4Schematic diagram of the connection between the fiber SRS - type non - linear multimodal micro - beam splitting and combining device of the present invention and a laser and a scanning probe Figure 2 ;

[0028] 1. Dual - output dual - wavelength picosecond laser, 2. Femtosecond laser, 3. Acousto - optic modulator, 4. Fiber optic delay line, 5. First input single - mode polarization - maintaining fiber, 6. Second input single - mode polarization - maintaining fiber, 7. First input hollow anti - resonant fiber, 8. First fiber optic input collimator, 9. Second fiber optic input collimator, 10. Third fiber optic input collimator, 11. First long - pass dichroic mirror, 12. Polarization beam splitter prism, 13. First mirror, 14. Electrically controlled displacement stage, 15. Second long - pass dichroic mirror, 16. Third long - pass dichroic mirror, 17. Second mirror, 18. Fourth long - pass dichroic mirror, 19. First single - photon detector, 20. Second single - photon detector, 21. Third single - photon detector, 22. First fiber optic input / output coupler, 23. Second fiber optic input / output coupler, 24. Third fiber optic input / output coupler, 25. Second input / output hollow anti - resonant fiber, 26. Fiber piezoelectric cylinder scanning probe, 27. Third input / output hollow anti - resonant fiber, 28. Input / output large - core diameter fiber, 29. Fiber MEMS scanning probe, 30. Optical glass plate, 100. Non - linear excitation light unit, 200. Sample detection signal light, 300. Fiber optic input collimation unit, 400. Input / output coupling unit, 500. Primary beam splitting unit, 600. Secondary beam splitting unit, 700. Conversion unit. Detailed implementation mode

[0029] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The specific embodiments described are only for explaining the present invention and are not intended to limit the present invention.

[0030] As Figure 1 shown, it is a schematic diagram of the structure of the fiber SRS - type non - linear multimodal micro - beam splitting and combining device of the present invention Figure 1 As Figure 3 shown, it is a schematic diagram of the connection between the fiber SRS - type non - linear multimodal micro - beam splitting and combining device of the present invention and a laser and a scanning probe Figure 1 The fiber SRS - type non - linear multimodal micro - beam splitting and combining device includes a non - linear excitation light unit, a first long - pass dichroic mirror 11, an input / output coupling unit 400, a primary beam splitting unit 500, a second mirror 17, a secondary beam splitting unit 600, a conversion unit 700, a fourth long - pass dichroic mirror 18, and a fiber probe.

[0031] The non-linear excitation light unit 100 receives a P-polarized femtosecond non-linear excitation light pulse and two S-polarized picosecond non-linear excitation light pulses, combines them through a first long-pass dichroic mirror to generate a non-linear excitation light pulse. The input / output coupling unit 400 includes an optical fiber input / output coupler and an input / output hollow anti-resonant fiber. The non-linear excitation light pulse is coupled into the air core of the input / output hollow anti-resonant fiber through the optical fiber input / output coupler, and the non-linear excitation light pulse is output to an optical fiber probe. The optical fiber probe collects three kinds of signal lights from the sample, including SRS signal light, SHG signal light and TPEF signal light. The input / output hollow anti-resonant fiber is connected to the optical fiber input / output coupler, and receives the SHG and TPEF signal lights returned by the optical fiber probe through the cladding of the input / output hollow anti-resonant fiber, and is collimated and emitted through the optical fiber input / output coupler and returned to the first beam splitting unit. The first beam splitting unit 500 includes a second long-pass dichroic mirror, which separates the non-linear excitation light pulse, SHG signal light and TPEF signal light. The fourth long-pass dichroic mirror separates stray light and turns the SRS signal light transmitted forward. The second beam splitting unit 600 separates the SRS signal light. The conversion unit 700 converts the SRS signal light, SHG signal light and TPEF signal light into electrical signals.

[0032] Specifically, the non-linear excitation light unit 100 includes two input single-mode polarization-maintaining optical fibers respectively connected to a beam of S-polarized picosecond non-linear excitation light pulse and an input hollow anti-resonant fiber connected to a beam of P-polarized femtosecond non-linear excitation light pulse. The optical fiber input collimation unit includes an optical fiber input collimator. The two beams of S-polarized picosecond non-linear excitation light pulses and a beam of P-polarized femtosecond non-linear excitation light pulse are respectively collimated and emitted through the optical fiber input collimator. The P-polarized femtosecond non-linear excitation light pulse is turned by a first reflector and combined with the two beams of S-polarized picosecond non-linear excitation light pulses through a first long-pass dichroic mirror to obtain a non-linear excitation light pulse.

[0033] Specifically, the second beam splitting unit 600 includes a third long-pass dichroic mirror 16 and a second reflector 17. The third long-pass dichroic mirror 16 separates the SHG signal light, and the TPEF signal light is turned by the second reflector 17.

[0034] Specifically, the conversion unit 700 includes three single-photon detectors, which convert the SRS signal light, SHG signal light and TPEF signal light into electrical signals in three paths.

[0035] As Figure 2 shown, it is a schematic structural diagram of the fiber SRS-type non-linear multimodal micro beam splitting and combining device of the present invention. As Figure 3As shown in the figure, it is a schematic connection diagram of the fiber SRS-based non-linear multimodal micro beam splitter / combiner device of the present invention with a laser and a scanning probe.

[0036] As Figure 1 shown, the device includes a first input single-mode polarization-maintaining fiber 5, a second input single-mode polarization-maintaining fiber 6, a first input hollow anti-resonant fiber 7, a first fiber input collimator 8, a second fiber input collimator 9, a third fiber input collimator 10, a first long-pass dichroic mirror 11, a polarization beam splitter prism 12, a first mirror 13, an electronically controlled displacement stage 14, a second long-pass dichroic mirror 15, a third long-pass dichroic mirror 16, a second mirror 17, a fourth long-pass dichroic mirror 18, a first single-photon detector 19, a second single-photon detector 20, a third single-photon detector 21, a first fiber input / output coupler 22, a second fiber input / output coupler 23, a third fiber input / output coupler 24, a second input / output hollow anti-resonant fiber 25, a second input / output hollow anti-resonant fiber 27, and an optical glass plate 30, where:

[0037] The first input single-mode polarization-maintaining fiber 5 is used to access an S-polarized picosecond non-linear excitation light pulse with an output wavelength of 1015 - 1070 nm and a pulse width of 1 ps to 20 ps; the second input single-mode polarization-maintaining fiber 6 is used to access an S-polarized picosecond non-linear excitation light pulse with an output wavelength of 740 - 1015 nm from a dual-output dual-wavelength picosecond laser 1 and a pulse width of 1 ps to 20 ps; the first input hollow anti-resonant fiber 7 is used to access a P-polarized femtosecond non-linear excitation light pulse with an output wavelength of 780 nm from a femtosecond laser 2 and a pulse width of 80 fs to 200 fs;

[0038] The first fiber input collimator 8 is used to collimate the light pulse accessed by the first input single-mode polarization-maintaining fiber 5; the second fiber input collimator 9 is used to collimate the light pulse accessed by the second input single-mode polarization-maintaining fiber 6; the third fiber input collimator 10 is used to collimate the light pulse accessed by the first input hollow anti-resonant fiber 7;

[0039] The first long-pass dichroic mirror 11 has a transmission band of 1020 - 1550 nm and a reflection wavelength of 520 - 985 nm, and is used to combine two picosecond S-polarized non-linear excitation light pulses and one femtosecond P-polarized non-linear excitation light pulse; the polarization beam splitter prism 12 has a working band of 600 - 1100 nm and is used to combine an S-polarized picosecond non-linear excitation light pulse with a wavelength of 740 - 1015 nm and a P-polarized femtosecond light pulse with a wavelength of 780 nm; the first mirror 13 is used to turn the traveling direction of the 780-nm P-polarized non-linear excitation femtosecond light pulse;

[0040] The electronically controlled displacement stage 14 is used to control the displacement of the second long-pass dichroic mirror 15 in the vertical direction. Under the fiber piezoelectric cylinder scanning probe, the second long-pass dichroic mirror 15 is displaced to the optical path where the first fiber input / output coupler 22 is located. The second long-pass dichroic mirror 15 has a transmission band of 750 - 1600 nm and a reflection wavelength of 350 - 720 nm, and is used to separate the non-linear excitation light pulse and the reflected SHG and TPEF signal lights; the third long-pass dichroic mirror 16 is used to separate the SHG signal light; the second mirror 17 is used to turn the traveling direction of the TPEF signal light; the fourth long-pass dichroic mirror 18 has a transmission band of 1020 - 1550 nm and a reflection wavelength of 520 - 985 nm, and is used to separate stray light and turn the forward-transmitted SRS signal light;

[0041] The first single-photon detector 19 is used to convert the SHG signal light into an electrical signal; the second single-photon detector 20 is used to convert the TPEF signal light into an electrical signal; the third single-photon detector 21 is used to convert the SRS signal light into an electrical signal; the first fiber input / output coupler 22 is used to couple the non-linear excitation light pulse into the air core of the second input / output hollow anti-resonant fiber 25, and collimate and output the SHG and TPEF signal lights reflected and received by the cladding of the second input / output hollow anti-resonant fiber 25; the second fiber input / output coupler 23 is connected to the second input / output hollow anti-resonant fiber 25; the third fiber input / output coupler 24 is used to collimate and output the SRS signal light received by the cladding of the third input / output hollow anti-resonant fiber 27.

[0042] As Figure 3 shown, in the fiber piezoelectric cylinder scanning probe mode, the first input single-mode polarization-maintaining fiber 5 is connected to the acousto-optic modulator 3 and the dual-output dual-wavelength picosecond laser 1, so as to output a modulated S-polarized picosecond non-linear excitation light pulse with a wavelength of 1015 - 1070 nm and a pulse width of 1 ps to 20 ps; the second input single-mode polarization-maintaining fiber 6 is connected to the dual-output dual-wavelength picosecond laser 1, so as to output an S-polarized picosecond non-linear excitation light pulse with a wavelength of 740 - 1015 nm and a pulse width of 1 ps to 20 ps; the first input hollow anti-resonant fiber 6 is connected to the femtosecond laser 2, so as to output a P-polarized femtosecond non-linear excitation light pulse with a wavelength of 780 nm and a pulse width of 80 fs to 200 fs. The second input / output hollow anti-resonant fiber 25 is connected to the a end of the fiber piezoelectric cylinder scanning probe 26, and the third input / output hollow anti-resonant fiber 27 is connected to the b end of the fiber piezoelectric cylinder scanning probe 26. The a end is for the input of the non-linear excitation light, and the b end is for the output of the SRS signal light.

[0043] As Figure 2In the fiber optic MEMS scanning probe mode shown, the device includes a first input single-mode polarization-maintaining fiber 5, a second input single-mode polarization-maintaining fiber 6, a first input hollow anti-resonant fiber 7, a first fiber optic input collimator 8, a second fiber optic input collimator 9, a third fiber optic input collimator 10, a first long-pass dichroic mirror 11, a polarization beam splitter prism 12, a first mirror 13, an electronically controlled displacement stage 14, a second long-pass dichroic mirror 15, a third long-pass dichroic mirror 16, a second mirror 17, a fourth long-pass dichroic mirror 18, a first single-photon detector 19, a second single-photon detector 20, a third single-photon detector 21, a first fiber optic input / output coupler 22, a second fiber optic input / output coupler 23, a third fiber optic input / output coupler 24, a second input / output hollow anti-resonant fiber 25, a second input / output hollow anti-resonant fiber 27, an input / output large-core fiber 28, and an optical glass plate 30, where:

[0044] The first input single-mode polarization-maintaining fiber 5 is used to access an S-polarized picosecond nonlinear excitation light pulse with an output wavelength of 1015 - 1070 nm and a pulse width of 1 ps to 20 ps; the second input single-mode polarization-maintaining fiber 6 is used to access an S-polarized picosecond nonlinear excitation light pulse with an output wavelength of 740 - 1015 nm from a dual-output dual-wavelength picosecond laser 1 and a pulse width of 1 ps to 20 ps; the first input hollow anti-resonant fiber 7 is used to access a P-polarized femtosecond nonlinear excitation light pulse with an output wavelength of 780 nm from a femtosecond laser 2 and a pulse width of 80 fs to 200 fs;

[0045] The first fiber optic input collimator 8 is used to collimate the light pulse accessed by the first input single-mode polarization-maintaining fiber 5; the second fiber optic input collimator 9 is used to collimate the light pulse accessed by the second input single-mode polarization-maintaining fiber 6; the third fiber optic input collimator 10 is used to collimate the light pulse accessed by the first input hollow anti-resonant fiber 7.

[0046] The first long-pass dichroic mirror 11 has a transmission band of 1020 - 1550 nm and a reflection wavelength of 520 - 985 nm, and is used to combine two picosecond nonlinear excitation light pulses and one femtosecond nonlinear excitation light pulse; the polarization beam splitter prism 12 has a working band of 600 - 1100 nm and is used to combine an S-polarized picosecond nonlinear excitation light pulse with a wavelength of 740 - 1015 nm and a P-polarized femtosecond light pulse with a wavelength of 780 nm; the first mirror 13 is used to turn the traveling direction of the 780-nm P-polarized nonlinear excitation femtosecond light pulse;

[0047] The electronically controlled displacement stage 14 is used to control the displacement of the second long-pass dichroic mirror 15 in the vertical direction. In the fiber optic MEMS scanning probe mode, the second long-pass dichroic mirror 15 is displaced to the optical path where the second fiber input / output coupler 23 is located. The second long-pass dichroic mirror 15 has a transmission band of 750 - 1600 nm and a reflection wavelength of 350 - 720 nm, and is used to separate the non-linear excitation light pulse and the reflected SHG and TPEF signal light; the third long-pass dichroic mirror 16 is used to separate the SHG signal light; the second mirror 17 is used to turn the traveling direction of the TPEF signal light; the fourth long-pass dichroic mirror 18 has a transmission band of 1020 - 1550 nm and a reflection wavelength of 520 - 985 nm, and is used to separate stray light and turn the forward-transmitted SRS signal light.

[0048] The first single-photon detector 19 is used to convert the SHG signal light into an electrical signal; the second single-photon detector 20 is used to convert the TPEF signal light into an electrical signal; the third single-photon detector 21 is used to convert the SRS signal light into an electrical signal; the first fiber input / output coupler 22 is used to couple the non-linear excitation light pulse into the air core of the second input / output hollow anti-resonant fiber 25 and collimate it for output; the third fiber input / output coupler 24 is used to collimate the SRS signal light received by the cladding of the third input / output hollow anti-resonant fiber 27 for output.

[0049] When switching the fiber piezoelectric cylinder scanning probe to the fiber optic MEMS scanning probe, the second fiber input / output coupler 23 is used to collimate and output the reflected SHG and TPEF signal light received by the cladding of the input / output large-core diameter fiber 28; the optical glass plate 30 is used to support each part of the optical devices and modules in the beam splitting and combining device.

[0050] As Figure 4 shown, in the fiber optic MEMS scanning probe, the first input single-mode polarization-maintaining fiber 5 is connected to the acousto-optic modulator 3 and the dual-output dual-wavelength picosecond laser 1, so as to output a modulated S-polarized picosecond non-linear excitation light pulse with a wavelength of 1015 - 1070 nm and a pulse width of 1 ps to 20 ps; the second input single-mode polarization-maintaining fiber 6 is connected to the dual-output dual-wavelength picosecond laser 1, so as to output an S-polarized picosecond non-linear excitation light pulse with a wavelength of 740 - 1015 nm and a pulse width of 1 ps to 20 ps; the first input hollow anti-resonant fiber 6 is connected to the femtosecond laser 2, so as to output a P-polarized femtosecond non-linear excitation light pulse with a wavelength of 780 nm and a pulse width of 80 fs to 200 fs. The second input / output hollow anti-resonant fiber 25 is connected to the a end of the fiber optic MEMS scanning probe 29, the input / output large-core diameter fiber 28 is connected to the b end of the fiber optic MEMS scanning probe 29, and the third input / output hollow anti-resonant fiber 27 is connected to the c end of the fiber optic MEMS scanning probe 27.

[0051] An optical fiber SRS-based non-linear multimodal micro beam splitting and combining device and method of the present invention, the method comprising the following steps:

[0052] Step 1: The first input single-mode polarization-maintaining optical fiber is connected to a dual-output dual-wavelength picosecond laser to output an S-polarized picosecond non-linear excitation optical pulse with a wavelength of 1015 - 1070 nm and a pulse width of 1 ps to 20 ps; the second input single-mode polarization-maintaining optical fiber is used to connect to the dual-output dual-wavelength picosecond laser to output an S-polarized picosecond non-linear excitation optical pulse with a wavelength of 740 - 1015 nm and a pulse width of 1 ps to 20 ps; the first input hollow anti-resonant optical fiber is used to connect to a femtosecond laser to output a P-polarized femtosecond non-linear excitation optical pulse with a wavelength of 780 nm and a pulse width of 80 fs to 200 fs.

[0053] Step 2: The first fiber input collimator collimates the optical pulse connected by the first input single-mode polarization-maintaining optical fiber, the second fiber input collimator collimates the optical pulse connected by the second input single-mode polarization-maintaining optical fiber, and the third fiber input collimator collimates the optical pulse connected by the first input hollow anti-resonant optical fiber.

[0054] Step 3: After the first mirror turns the traveling direction of the 780-nm P-polarized non-linearly excited femtosecond optical pulse, the polarization beam splitter prism combines the 740 - 1015-nm S-polarized picosecond optical pulse and the 780-nm P-polarized non-linearly excited femtosecond optical pulse; the first long-pass dichroic mirror combines two non-linearly excited picosecond optical pulses and one non-linearly excited femtosecond optical pulse.

[0055] Step 4: The three combined light beams are transmitted through the second long-pass dichroic mirror, and the first fiber input / output coupler couples the non-linearly excited optical pulse into the air core of the second input / output hollow anti-resonant optical fiber, and the second input / output hollow anti-resonant optical fiber transmits the non-linearly excited optical pulse from end a into the fiber piezoelectric cylinder scanning probe.

[0056] Step 5: The fiber piezoelectric cylinder scanning probe collects the SRS, SHG, and TPEF signal lights generated by the sample, the cladding of the second input / output hollow anti-resonant optical fiber receives the SHG and TPEF signal lights reflected back by the fiber piezoelectric cylinder scanning probe, and is collimated and emitted back to the device by the first fiber input / output coupler; the input / output large-core diameter optical fiber receives the SRS signal light forward-transmitted by the fiber piezoelectric cylinder scanning probe from end b, and is collimated and emitted back to the device by the fourth fiber input / output coupler.

[0057] Step 6: The second-longest pass dichroic mirror separates the non-linear excitation light pulse and the reflected SHG and TPEF signal lights that return. After the third-longest pass dichroic mirror separates the reflected SHG signal light, the first single-photon detector converts the SHG signal light into an electrical signal; after the second mirror turns the TPEF signal light, the second single-photon detector converts the TPEF signal light into an electrical signal; after the fourth-longest pass dichroic mirror separates the stray light and the forward-propagating SRS signal light, the third single-photon detector converts the SRS signal light into an electrical signal.

[0058] When the fiber piezoelectric cylinder scanning probe is switched to a fiber MEMS scanning probe, the steps are as follows:

[0059] Step 1: The first input single-mode polarization-maintaining fiber accesses the S-polarized picosecond non-linear excitation light pulse with a wavelength of 1015 - 1070 nm output by the dual-output dual-wavelength picosecond laser, and the pulse width is 1 ps to 20 ps; the second input single-mode polarization-maintaining fiber is used to access the S-polarized picosecond non-linear excitation light pulse with a wavelength of 740 - 1015 nm output by the dual-output dual-wavelength picosecond laser, and the pulse width is 1 ps to 20 ps; the first input hollow anti-resonant fiber is used to access the P-polarized femtosecond non-linear excitation light pulse with a wavelength of 780 nm output by the femtosecond laser, and the pulse width is 80 fs to 200 fs.

[0060] Step 2: The first fiber input collimator collimates the light pulse accessed by the first input single-mode polarization-maintaining fiber, the second fiber input collimator collimates the light pulse accessed by the second input single-mode polarization-maintaining fiber, and the third fiber input collimator collimates the light pulse accessed by the first input hollow anti-resonant fiber.

[0061] Step 3: After the first mirror turns the traveling direction of the 780-nm P-polarized non-linearly excited femtosecond light pulse, the polarization beam splitter prism combines the 740 - 1015-nm S-polarized picosecond light pulse and the 780-nm P-polarized non-linearly excited femtosecond light pulse; the first long-pass dichroic mirror combines the two non-linearly excited picosecond light pulses and one non-linearly excited femtosecond light pulse.

[0062] Step 4: The three combined light beams are transmitted through the second long-pass dichroic mirror, and the first fiber input-output coupler

[0063] couples the non-linearly excited picosecond and non-linearly excited femtosecond light pulses into the air core of the second input-output hollow anti-resonant fiber. The second input-output hollow anti-resonant fiber transmits the non-linearly excited light pulse from end a into the fiber MEMS scanning probe.

[0064] Step 5: The fiber optic MEMS scanning probe collects the SRS, SHG, and TPEF signal lights generated by the sample. The input / output large-core fiber receives the SRS signal light forward-transmitted by the fiber optic MEMS scanning probe from end b, and is collimated and emitted back to the device by the fourth fiber optic input / output coupler. The cladding of the third input / output hollow anti-resonant fiber receives the SHG and TPEF signal lights forward-transmitted by the fiber optic MEMS scanning probe from end c, and is collimated and emitted back to the device by the third fiber optic input / output coupler.

[0065] Step 6: The second long-pass dichroic mirror is driven by an electric control displacement stage and moves to the same horizontal line as the second fiber optic input / output coupler to reflect the returned SHG and TPEF signal lights. After the third long-pass dichroic mirror separates the reflected SHG signal light, the first single-photon detector converts the SHG signal light into an electrical signal. After the second reflector deflects the TPEF signal light, the second single-photon detector converts the TPEF signal light into an electrical signal. After the fourth long-pass dichroic mirror separates the stray light and the forward-transmitted SRS signal light, the third single-photon detector converts the SRS signal light into an electrical signal.

[0066] It should be noted that although the present invention has been shown and described with reference to specific exemplary embodiments of the present invention, those skilled in the art should understand that the present invention is not limited to the above embodiments. Any changes to the present invention fall within the protection scope of the present invention application.

Claims

1. An optical fiber SRS-based nonlinear multimode micro beam splitting and combining device, characterized in that, The fiber-optic SRS-based non-linear multimode micro beam splitting and combining device includes a non-linear excitation light unit, a first long-pass dichroic mirror, an input / output coupling unit, a primary beam splitting unit, a second reflector, a secondary beam splitting unit, a conversion unit, a fourth long-pass dichroic mirror, and an optical fiber probe; The non-linear excitation light unit accesses a P-polarized femtosecond non-linear excitation light pulse and two S-polarized picosecond non-linear excitation light pulses, combines them through the first long-pass dichroic mirror to generate a non-linear excitation light pulse. The input / output coupling unit includes an optical fiber input / output coupler and an input / output hollow anti-resonant optical fiber; the non-linear excitation light pulse is coupled into the air core of the input / output hollow anti-resonant optical fiber through the optical fiber input / output coupler, and the non-linear excitation light pulse is output to the optical fiber probe; the optical fiber probe collects three signal lights from the sample, including SRS signal light, SHG signal light, and TPEF signal light. The input / output hollow anti-resonant optical fiber is connected to the optical fiber input / output coupler, and the SHG and TPEF signal lights returned by the optical fiber probe are received through the cladding of the input / output hollow anti-resonant optical fiber, and are collimated and emitted through the optical fiber input / output coupler and returned to the primary beam splitting unit; the primary beam splitting unit includes a second long-pass dichroic mirror, which separates the non-linear excitation light pulse from the SHG signal light and the TPEF signal light; the fourth long-pass dichroic mirror separates stray light and deflects the forward-propagating SRS signal light; the secondary beam splitting unit separates the SRS signal light; the conversion unit converts the SRS signal light, SHG signal light, and TPEF signal light into electrical signals.

2. The fiber SRS type non-linear multi-mode micro beam splitting and combining device according to claim 1, characterized in that, The non-linear excitation light unit includes two input single-mode polarization-maintaining optical fibers, each accessing a beam of S-polarized picosecond non-linear excitation light pulse, and an input hollow anti-resonant optical fiber accessing a beam of P-polarized femtosecond non-linear excitation light pulse. The optical fiber input collimation unit includes an optical fiber input collimator. The two beams of S-polarized picosecond non-linear excitation light pulses and the beam of P-polarized femtosecond non-linear excitation light pulse are respectively collimated and emitted through the optical fiber input collimator. The P-polarized femtosecond non-linear excitation light pulse is deflected by the first reflector and combined with the two beams of S-polarized picosecond non-linear excitation light pulses through the first long-pass dichroic mirror to obtain a non-linear excitation light pulse.

3. The fiber SRS type nonlinear multimode micro beam splitting and combining device according to claim 1, characterized in that, The first input single-mode polarization-maintaining optical fiber accesses a double-output dual-wavelength picosecond laser to output an S-polarized picosecond non-linear excitation light pulse with a wavelength of 1015 - 1070 nm and a pulse width of 1 ps to 20 ps; the second input single-mode polarization-maintaining optical fiber accesses a double-output dual-wavelength picosecond laser to output an S-polarized picosecond non-linear excitation light pulse with a wavelength of 740 - 862 nm and a pulse width of 1 ps to 20 ps; the first input hollow anti-resonant optical fiber accesses a femtosecond laser to output a P-polarized femtosecond non-linear excitation light pulse with a wavelength of 780 nm and a pulse width of 80 fs to 200 fs.

4. The fiber SRS type non-linear multi-modal micro beam splitting and combining device according to claim 1, characterized in that, The secondary beam splitting unit includes a third long-pass dichroic mirror and a second reflector. The third long-pass dichroic mirror separates the SHG signal light, and the TPEF signal light is deflected by the second reflector.

5. The fiber optic SRS-based non-linear multi-modal micro beam splitting and combining device according to claim 1, characterized in that, The conversion unit includes three single-photon detectors, which convert the SRS signal light, SHG signal light, and TPEF signal light into electrical signals in three paths.

6. The fiber optic SRS-based nonlinear multimode micro beam splitting and combining device according to claim 1, wherein The fourth long-pass dichroic mirror deflects the SRS signal light through displacement control.

7. The fiber optic SRS type non-linear multi-modal micro beam splitting and combining device according to claim 1, characterized in that, The optical fiber probe adopts an optical fiber piezoelectric cylinder scanning probe mode or an optical fiber MEMS scanning probe mode.

8. A fiber optic SRS type non-linear multimode micro beam splitting and combining device according to claim 7, characterized in that, In the optical fiber piezoelectric cylinder scanning probe mode, the input / output coupling unit includes two optical fiber input / output couplers and an input / output hollow anti-resonant optical fiber, and an input / output hollow anti-resonant optical fiber suspended by combining one path. The position of the second long-pass dichroic mirror is controlled to change the SHG signal light and TPEF signal light reflected back to this path of the optical fiber input / output coupler.

9. The fiber optic SRS type nonlinear multimode micro beam splitting and combining device according to claim 7, characterized in that, In the optical fiber MEMS scanning probe mode, the input / output coupling unit includes three optical fiber input / output couplers and an input / output hollow anti-resonant optical fiber. The position of the second long-pass dichroic mirror is controlled to change the SHG signal light and TPEF signal light reflected back to one path of the optical fiber input / output coupler connected to the output end of the optical fiber MEMS scanning probe.

10. A fiber optic SRS - type non - linear multimode micro - beam splitting and combining method implemented by using a fiber optic SRS - type non - linear multimode micro - beam splitting and combining device according to any one of claims 1 to 9, characterized in that, This method includes the following steps: S1, Access a P-polarized femtosecond nonlinear excitation light pulse and two S-polarized picosecond nonlinear excitation light pulses, and combine them through the first long-pass dichroic mirror to generate a nonlinear excitation light pulse. S2, Output the nonlinear excitation light pulse, receive the returned SRS signal light, SHG signal light, and TPEF signal light, and collimate and output them back. S3, Perform a first beam splitting to separate the nonlinear excitation light pulse and the SHG signal light and TPEF signal light that are output and returned. S3, Separate stray light and deflect the SRS signal light transmitted forward. S4, Perform a second beam splitting to separate the SHG signal light and deflect the TPEF signal light. S5, Convert the SRS signal light, SHG signal light, and TPEF signal light into electrical signals.

Images