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

Abstract

The invention discloses an optical fiber CARS 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 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 non-linear excitation light pulse is output, returned CARS signal light, SHG signal light and TPEF signal light are received and collimated, emitted and returned; primary beam splitting is carried out, and nonlinear excitation light pulses and emitted and returned CARS, SHG and TPEF signal light are separated; the CARS signal light, the SHG signal light and the TPEF signal light which are transmitted backwards are switched; and carrying out secondary beam splitting to separate out CARS signal light, SHG signal light and turning TPEF signal light. 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 multi-modal non-linear spectral microscopy imaging, and particularly relates to a fiber CARS-type non-linear multi-modal micro beam splitting and combining device and method applicable to a wide band and two probes. Background Art

[0002] Traditional optical imaging techniques (such as wide-field fluorescence or confocal microscopy) are limited by the optical diffraction limit, phototoxicity, and dependence on exogenous labels, and it is difficult to achieve high-specificity and low-damage three-dimensional dynamic observation in vivo or in a complex tissue environment. Non-linear optical techniques break through these limitations through the characteristics of the non-linear interaction between ultrafast lasers and samples. Different non-linear optical microscopy techniques can image specific molecules or structures. Coupling multiple non-linear imaging techniques can perform imaging analysis on organisms from multiple dimensions such as tissue structure and molecular metabolism.

[0003] CARS (coherent anti-Stokes Raman scattering) microscopy imaging technology uses the molecular vibration in a sample to be measured for label-free, non-contact, and chemically selective microscopy imaging. Its essence is the four-wave mixing effect of pump light, Stokes light, probe light, and anti-Stokes light generated by the molecular vibration energy level of the sample to be measured. When the frequency difference between the pump light and the Stokes light is equal to the molecular vibration energy level of the sample to be measured and the phase matching condition is satisfied, the anti-Stokes light of the sample to be measured, that is, the coherent anti-Stokes Raman scattering signal, will be excited. SHG (second-harmonic generation) microscopy imaging technology uses the second-order non-linear susceptibility χ of the sample to be measured (2) to achieve the interaction between light and matter. The 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 non-linear susceptibility χ (2) requires a non-centrosymmetric structure, so it can realize the imaging of biological tissues with non-centrosymmetric structures, such as collagen fibers, muscle fibers, etc. TPEF (two-photon excitation fluorescence) microscopy imaging technology uses the two-photon absorption transition effect of the molecules in the sample to be measured. Under the action of an ultrashort pulsed laser, two photons are simultaneously absorbed and transition to a higher electronic excited state, and then relax back to the ground state to emit fluorescence, emitting fluorescence with a wavelength shorter than that of the incident light. The complementarity of the three non-linear optical spectral imaging techniques of CARS, SHG, and TPEF in terms of chemical specificity, structural sensitivity, and dynamic observation ability is very suitable for constructing a CARS-type non-linear multi-modal imaging system integrating CARS, SHG, and TPEF.

[0004] In the conventional CARS-type non-linear multimodal microscopy system, the beam splitting and combining device is usually designed for a single wavelength and a single probe, which limits the ability to obtain wide-band information and narrows the application scope of the imaging system. Moreover, the beam splitting and combining device is built on a conventional optical platform using large-sized optical components, which has a large spatial size, is vulnerable to environmental interference, has poor system stability, high operation and maintenance costs, and cannot be configured as a portable instrument for clinical applications. Summary of the Invention

[0005] In order to overcome the problems existing in the existing devices and methods, the present invention aims to propose a fiber-optic CARS-type non-linear multimodal micro beam splitting and combining device and method, which realizes fiber-optic CARS-type non-linear multimodal micro beam splitting and combining by using the principle of backward excitation, and simultaneously adapts to a fiber-optic piezoelectric cylinder scanning probe and a fiber-optic MEMS scanning probe.

[0006] The present invention is realized by the following technical solutions:

[0007] In a first aspect, the present invention realizes a fiber-optic CARS-type non-linear multimodal micro beam splitting and combining device, which 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 mirror, a secondary beam splitting unit, a conversion unit, and a fiber-optic probe;

[0008] 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, and combines them through the first long-pass dichroic mirror to generate a non-linear excitation light pulse. The input / output coupling unit includes a fiber-optic 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 fiber-optic input / output coupler, and the non-linear excitation light pulse is output to the fiber-optic probe; the fiber-optic probe collects three kinds of signal lights from the sample, including CARS 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 CARS signal light, SHG signal light, and TPEF signal light 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 non-linear excitation light pulse and the CARS, SHG, and TPEF signal lights; the second mirror switches the CARS signal light, SHG signal light, and TPEF signal lights transmitted backward; the secondary beam splitting unit separates the CARS signal light and the SHG signal light, and deflects the TPEF signal light; the conversion unit converts the CARS signal light, SHG signal light, and TPEF signal lights into electrical signals.

[0009] In some embodiments, the non-linear excitation light unit includes two input single-mode polarization-maintaining optical fibers respectively accessing a beam of S-polarized picosecond non-linear excitation light pulses and one input hollow anti-resonant optical fiber accessing a beam of P-polarized femtosecond non-linear excitation light pulses. The fiber input collimation unit includes a fiber input collimator. The two beams of S-polarized picosecond non-linear excitation light pulses and one beam of P-polarized femtosecond non-linear excitation light pulses are respectively collimated and emitted by the fiber input collimator. The P-polarized femtosecond non-linear excitation light pulses are turned by a first mirror and combined with the two beams of S-polarized picosecond non-linear excitation light pulses through a first long-pass dichroic mirror to obtain non-linear excitation light pulses.

[0010] In some embodiments, the first input single-mode polarization-maintaining optical fiber accesses an S-polarized picosecond non-linear excitation light pulse with an output wavelength of 1015 - 1070 nm from a dual-output dual-wavelength picosecond laser, and the pulse width is 1 ps to 20 ps; the second input single-mode polarization-maintaining optical fiber accesses an S-polarized picosecond non-linear excitation light pulse with an output wavelength of 740 - 862 nm from a dual-output dual-wavelength picosecond laser, and the pulse width is 1 ps to 20 ps; the first input hollow anti-resonant optical fiber accesses a P-polarized femtosecond non-linear excitation light pulse with an output wavelength of 780 nm from a femtosecond laser, and the pulse width is 80 fs to 200 fs.

[0011] In some embodiments, the secondary beam splitting unit includes a third long-pass dichroic mirror, a fourth long-pass dichroic mirror and a third mirror. The CARS signal light is separated by the third long-pass dichroic mirror, the SHG signal light is separated by the fourth long-pass dichroic mirror, and the TPEF signal light is turned by the third mirror.

[0012] In some embodiments, the conversion unit includes three single-photon detectors, which convert the CARS signal light, SHG signal light and TPEF signal light into electrical signals in three paths.

[0013] In some embodiments, the second mirror switches the reflected CARS signal light, SHG signal light and TPEF signal light by controlling the angular position.

[0014] The fiber probe adopts a fiber piezoelectric cylinder scanning probe mode or a fiber MEMS scanning probe mode.

[0015] In some embodiments, in the fiber piezoelectric cylinder scanning probe mode, the input-output coupling unit includes a path of fiber input-output coupler and input-output hollow anti-resonant optical fiber, and a suspended path of fiber input-output coupler and input-output hollow anti-resonant optical fiber. The position of the second mirror is controlled to change the CARS signal light, SHG signal light and TPEF signal light reflected back to this path of fiber input-output coupler.

[0016] In some embodiments, in the fiber optic MEMS scanning probe mode, the input / output coupling unit includes two fiber optic input / output couplers and an input / output hollow anti-resonant fiber, and the position of the second mirror is controlled to change the CARS signal light, SHG signal light, and TPEF signal light that are reflected back by one of the fiber optic input / output couplers connected to the output end of the fiber optic MEMS scanning probe.

[0017] In a second aspect, the present invention realizes a fiber optic CARS-type non-linear multimodal beam splitting and combining method implemented by a fiber optic CARS-type non-linear multimodal beam splitting and combining device, and the method includes the following steps:

[0018] S1, Access a P-polarized femtosecond non-linear excitation light pulse and two S-polarized picosecond non-linear excitation light pulses, combine them through a first long-pass dichroic mirror to generate a non-linear excitation light pulse;

[0019] S2, Output the non-linear excitation light pulse, receive the returned CARS signal light, SHG signal light, and TPEF signal light, and collimate and output them back;

[0020] S3, Perform a first beam splitting to separate the non-linear excitation light pulse and the outgoing CARS, SHG, and TPEF signal lights;

[0021] S3, Switch the CARS signal light, SHG signal light, and TPEF signal light transmitted backward;

[0022] S4, Perform a second beam splitting to separate the CARS signal light, separate the SHG signal light, and deflect the TPEF signal light;

[0023] S5, Convert the CARS signal light, SHG signal light, and TPEF signal light into electrical signals.

[0024] Compared with existing devices, the beneficial technical effects that the present invention can achieve are as follows:

[0025] 1) On the basis of realizing the functions of beam splitting and combining, the device volume is significantly reduced by optimizing the structural design, and the spectral band range is effectively broadened; the adaptation of the two types of probes, namely the fiber optic piezoelectric cylinder scanning probe 25 and the fiber optic MEMS scanning probe 27, can meet multiple key performance and scenario uses, improving the imaging quality;

[0026] 2) Using single-mode polarization-maintaining fiber and hollow anti-resonant fiber as the beam input / output replaces the traditional large-scale spatial optical path system, improving the system stability;

[0027] 3) It can be adapted to the fiber optic piezoelectric cylinder scanning probe and the fiber optic MEMS scanning probe, improving the imaging ability of the CARS-type non-linear multimodal microscopy system and ensuring portability. Brief Description of the Drawings

[0028] Figure 1 Structural schematic of the fiber optic CARS - type non - linear multimodal micro - beam splitting and combining device of the present invention Figure 1 ;

[0029] Figure 2 Structural schematic of the fiber optic CARS - type non - linear multimodal micro - beam splitting and combining device of the present invention Figure 2 ;

[0030] Figure 3 Connection schematic of the fiber optic CARS - type non - linear multimodal micro - beam splitting and combining device of the present invention with a laser and a scanning probe Figure 1 ;

[0031] Figure 4 Connection schematic of the fiber optic CARS - type non - linear multimodal micro - beam splitting and combining device of the present invention with a laser and a scanning probe Figure 2 ;

[0032] Reference numerals: 1. Dual - output dual - wavelength picosecond laser, 2. Femtosecond laser, 3. Fiber optic delay line, 4. First input single - mode polarization - maintaining fiber, 5. Second input single - mode polarization - maintaining fiber, 6. First input hollow anti - resonant fiber, 7. First fiber optic input collimator, 8. Second fiber optic input collimator, 9. Third fiber optic input collimator, 10. First long - pass dichroic mirror, 11. Polarizing beam - splitting prism, 12. First mirror, 13. Second long - pass dichroic mirror, 14. Second mirror, 15. Electrically controlled rotating stage, 16. Third long - pass dichroic mirror, 17. Fourth long - pass dichroic mirror, 18. Third 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. Second input / output hollow anti - resonant fiber, 25. Fiber optic piezoelectric cylinder scanning probe, 26. Input / output large - core - diameter fiber, 27. Fiber optic MEMS scanning probe, 28. 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. First beam - splitting unit, 600. Second beam - splitting unit, 700. Conversion unit. Detailed Description of the Preferred Embodiments

[0033] The technical solution of the present invention will be further described in detail below in conjunction with the drawings and specific embodiments. The specific embodiments described are only for the purpose of explaining the present invention and are not intended to limit the present invention.

[0034] As Figure 1 shown, it is the structural schematic of the fiber optic CARS - type non - linear multimodal micro - beam splitting and combining device of the present inventionFigure 1 As Figure 3 shown, the schematic connection diagram of the fiber optic CARS-type non-linear multimodal micro beam splitting and combining device of the present invention with a laser and a scanning probe Figure 1 . The fiber optic SRS-type non-linear multimodal micro beam splitting and combining device includes a non-linear excitation light unit 100, a sample detection signal light 200, a fiber optic input collimation unit 300, a first reflector 12, a first long-pass dichroic mirror 10, an input / output coupling unit 400, a primary beam splitting unit 500, a second reflector 14, a secondary beam splitting unit 600, and a conversion unit 700.

[0035] In the mode of the fiber optic piezoelectric cylinder scanning probe, the device includes a first input single-mode polarization-maintaining fiber 4, a second input single-mode polarization-maintaining fiber 5, a first input hollow anti-resonant fiber 6, a first fiber optic input collimator 7, a second fiber optic input collimator 8, a third fiber optic input collimator 9, a first long-pass dichroic mirror 10, a polarization beam splitting prism 11, a first reflector 12, a second long-pass dichroic mirror 13, a second reflector 14, an electrically controlled rotating stage 15, a third long-pass dichroic mirror 16, a fourth long-pass dichroic mirror 17, a third reflector 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 second input / output hollow anti-resonant fiber 24, and an optical glass plate 28; wherein:

[0036] The first input single-mode polarization-maintaining fiber 4 is used 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 fiber 5 is used 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 fiber 6 is used 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 first fiber optic input collimator 7 is used to collimate the light pulse accessed by the first input single-mode polarization-maintaining fiber 4; the second fiber optic input collimator 8 is used to collimate the light pulse accessed by the second input single-mode polarization-maintaining fiber 5; the third fiber optic input collimator 9 is used to collimate the light pulse accessed by the first input hollow anti-resonant fiber 6.

[0037] The first long-pass dichroic mirror 10, with a transmission band of 1015 - 1070 nm and a reflection wavelength of 740 - 1015 nm, is used to combine two picosecond nonlinear excitation light pulses and one femtosecond nonlinear excitation light pulse; the polarization beam splitting prism 11, with an operating band of 600 - 1100 nm, is used to combine the S-polarized picosecond nonlinear excitation light pulse of 740 - 862 nm and the P-polarized femtosecond light pulse of 780 nm; the first reflecting mirror 12 is used to turn the traveling direction of the P-polarized nonlinear excitation femtosecond light pulse of 780 nm; the second long-pass dichroic mirror 13, with a transmission band of 740 - 1070 nm and a reflection wavelength of 350 - 740 nm, is used to separate the nonlinear excitation light pulse and the CARS, SHG, and TPEF signal lights reflected and returned by the first fiber input / output coupler 22; the second reflecting mirror 14 is used to switch the CARS and nonlinear modulation signal lights (such as including SHG and TPEF signal lights) returned by the fiber piezoelectric cylinder scanning probe 25; the electrically controlled rotary stage 15 is used to control the angular position of the second reflecting mirror 14; the third long-pass dichroic mirror 16 is used to separate the CARS (Coherent Anti-Stokes Raman Scattering) signal light; the fourth long-pass dichroic mirror 17 is used to separate the SHG (Second Harmonic Generation) signal light; the third reflecting mirror 18 is used to turn the TPEF (Two-Photon Excited Fluorescence) signal light; the first single-photon detector 19 is used to convert the CARS signal light into an electrical signal; the second single-photon detector 20 is used to convert the SHG signal light into an electrical signal; the third single-photon detector 21 is used to convert the TPEF signal light into an electrical signal; the first fiber input / output coupler 22 is used to couple the picosecond and femtosecond nonlinear excitation light pulses into the air core of the second input / output hollow anti-resonant fiber 24, and collimate and output the CARS signal light and the nonlinear modulation signal light (such as including SHG and TPEF signal lights) reflected by the cladding of the second input / output hollow anti-resonant fiber 24.

[0038] In the fiber piezoelectric cylinder scanning probe mode, the first input single-mode polarization-maintaining fiber 4 is connected to the fiber delay line 2 and the dual-output dual-wavelength picosecond laser 1, so as to delay and output the S-polarized picosecond nonlinear excitation light pulse with a wavelength of 1015 - 1070 nm and a pulse width of 1 ps - 20 ps; the second input single-mode polarization-maintaining fiber 5 is connected to the dual-output dual-wavelength picosecond laser 1, so as to output the S-polarized picosecond nonlinear excitation light pulse with a wavelength of 740 - 862 nm and a pulse width of 1 ps - 20 ps; the first input hollow anti-resonant fiber 6 is connected to the femtosecond laser 2, so as to output the P-polarized femtosecond nonlinear excitation light pulse with a wavelength of 780 nm and a pulse width of 80 fs - 200 fs. The second input / output hollow anti-resonant fiber 24 is connected to the fiber piezoelectric cylinder scanning probe 25, and returns the CARS and nonlinear modulation signal lights (such as including SHG and TPEF signal lights) to the device.

[0039] AsFigure 2 As shown, it is a schematic structure diagram of the fiber CARS-type non-linear multimodal micro beam splitter / combiner device of the present invention Figure 2 . Such as Figure 4 As shown, it is a schematic connection diagram of the fiber CARS-type non-linear multimodal micro beam splitter / combiner device of the present invention with a laser and a scanning probe Figure 2 . The fiber SRS-type non-linear multimodal micro beam splitter / combiner device includes a non-linear excitation light unit 100, a sample detection signal light 200, a fiber input collimation unit 300, a first reflector 12, a first long-pass dichroic mirror 10, an input / output coupling unit 400, a primary beam splitting unit 500, a second reflector 14, a secondary beam splitting unit 600, and a conversion unit 700.

[0040] In the fiber MEMS scanning probe mode, the device includes a first input single-mode polarization-maintaining fiber 4, a second input single-mode polarization-maintaining fiber 5, a first input hollow anti-resonant fiber 6, a first fiber input collimator 7, a second fiber input collimator 8, a third fiber input collimator 9, a first long-pass dichroic mirror 10, a polarization beam splitting prism 11, a first reflector 12, a second long-pass dichroic mirror 13, a second reflector 14, an electronically controlled rotating stage 15, a third long-pass dichroic mirror 16, a fourth long-pass dichroic mirror 17, a third reflector 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 second input / output hollow anti-resonant fiber 24, an input / output large-core fiber 26, and an optical glass plate 28; wherein:

[0041] The first input single-mode polarization-maintaining fiber 4 is connected to a fiber delay line 3 and a dual-output dual-wavelength picosecond laser 1, delaying and outputting 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 fiber 5 is connected to the dual-output dual-wavelength picosecond laser 1, outputting 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 fiber 6 is connected to a femtosecond laser 2, outputting 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 first fiber input collimator 7 collimates the light pulse input through the first input single-mode polarization-maintaining fiber 4; the second fiber input collimator 8 collimates the light pulse input through the second input single-mode polarization-maintaining fiber 5; the third fiber input collimator 9 is used to collimate the light pulse input through the first input hollow anti-resonant fiber 6.

[0042] The first long-pass dichroic mirror 10, with a transmission band of 1015 - 1070 nm and a reflection wavelength of 740 - 1015 nm, is used to combine two picosecond nonlinear excitation light pulses and one femtosecond nonlinear excitation light pulse; the polarization beam splitting prism 11, with an operating band of 600 - 1100 nm, is used to combine the S-polarized picosecond nonlinear excitation light pulse of 740 - 862 nm and the P-polarized femtosecond light pulse of 780 nm; the first reflecting mirror 12 is used to turn the traveling direction of the P-polarized femtosecond nonlinear excitation light pulse of 780 nm; the second long-pass dichroic mirror 13, with a transmission band of 740 - 1070 nm and a reflection wavelength of 350 - 740 nm, is used to separate the nonlinear excitation light pulse and the CARS, SHG, and TPEF signal lights reflected and returned by the first fiber input / output coupler; the second reflecting mirror 14 is used to switch the returned CARS, SHG, and TPEF signal lights; the electronically controlled rotary stage 15 is used to control the angular position of the second reflecting mirror 14; the third long-pass dichroic mirror 16 is used to separate the CARS (Coherent Anti-Stokes Raman Scattering) signal light; the fourth long-pass dichroic mirror 17 is used to separate the SHG (Second Harmonic Generation) signal light; the third reflecting mirror 18 is used to turn the TPEF (Two-Photon Excited Fluorescence) signal light; the first single-photon detector 19 is used to convert the CARS signal light into an electrical signal; the second single-photon detector 20 is used to convert the SHG signal light into an electrical signal; the third single-photon detector 21 is used to convert the TPEF signal light into an electrical signal; the first fiber input / output coupler 22 is used to couple the picosecond and femtosecond nonlinear excitation light pulses into the air core of the second input / output hollow anti-resonant fiber 24, and collimate and output the CARS, SHG, and TPEF signal lights received and reflected by the cladding of the second input / output hollow anti-resonant fiber 24.

[0043] In the fiber MEMS scanning probe mode, the first input single-mode polarization-maintaining fiber 4 is connected to the fiber delay line 2 and the dual-output dual-wavelength picosecond laser 1, so as to delay and output the S-polarized picosecond nonlinear 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 5 is connected to the dual-output dual-wavelength picosecond laser 1, so as to output the S-polarized picosecond nonlinear 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 fiber 6 is connected to the femtosecond laser 2, so as to output the P-polarized femtosecond nonlinear excitation light pulse with a wavelength of 780 nm and a pulse width of 80 fs to 200 fs. Since the fiber MEMS scanning probe has two ports, therefore, in this mode, there is also an input / output large-core fiber 26 connected to the second fiber input / output coupler 23 of the device, and the input / output large-core fiber 26 collimates and outputs the received CARS, SHG, and TPEF signal lights. The CARS, SHG, and TPEF signal lights returned by the fiber MEMS scanning probe 2727.

[0044] As Figure 4 shown, a fiber-optic CARS-type non-linear multimodal beam splitting and combining device of the present invention is used to implement a fiber-optic CARS-type non-linear multimodal beam splitting and combining method, which specifically includes the following steps:

[0045] A beam of S-polarized picosecond non-linear excitation light pulse and an input hollow anti-resonant fiber are respectively connected to access a beam of P-polarized femtosecond non-linear excitation light pulse. 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 by a fiber input collimator. The P-polarized femtosecond non-linear excitation light pulse is turned by a first mirror 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;

[0046] The non-linear excitation light pulse is coupled into the air core of the input / output hollow anti-resonant fiber through the fiber input / output coupler;

[0047] The non-linear excitation light pulse and the CARS, SHG, and TPEF signal lights reflected back by the fiber input / output coupler are separated by a second long-pass dichroic mirror; the second mirror switches the CARS signal light, SHG signal light, and TPEF signal light reflected back by the fiber input / output coupler. The secondary separation unit includes a third long-pass dichroic mirror, a fourth long-pass dichroic mirror, and a fifth long-pass dichroic mirror, and is separated into three paths of signal lights corresponding to the CARS signal light, the SHG signal light, and the TPEF signal respectively;

[0048] The CARS signal light, SHG signal light, and TPEF signal light reflected back by the internal structure of the fiber probe are received by the cladding of the input / output hollow anti-resonant fiber and collimated and emitted;

[0049] The CARS signal light, SHG signal light, and TPEF signal light are converted into electrical signals in three paths.

[0050] The specific description of the process is as follows:

[0051] Step 1: The first input single-mode polarization-maintaining fiber is connected to the output of a dual-output dual-wavelength picosecond laser to access 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 fiber is used to access 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 output by the dual-output dual-wavelength picosecond laser; the first input hollow anti-resonant fiber is used to access 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 output by a femtosecond laser.

[0052] Step 2: The first fiber input collimator collimates the optical pulses accessed by the first input single-mode polarization-maintaining fiber, the second fiber input collimator collimates the optical pulses accessed by the second input single-mode polarization-maintaining fiber, and the third fiber input collimator collimates the optical pulses accessed by the first input hollow anti-resonant fiber.

[0053] Step 3: After the first mirror turns the traveling direction of the femtosecond optical pulse excited by the P polarization at 780 nm, the polarization beam splitter combines the picosecond optical pulse with S polarization in the range of 740 - 862 nm and the femtosecond optical pulse excited by the P polarization at 780 nm; the first long-pass dichroic mirror combines two nonlinearly excited picosecond optical pulses and one nonlinearly excited femtosecond optical pulse.

[0054] 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 nonlinearly excited picosecond and nonlinearly excited femtosecond optical pulses into the air core of the second input / output hollow anti-resonant fiber. The second input / output hollow anti-resonant fiber transmits the nonlinearly excited optical pulses into the fiber piezoelectric cylinder scanning probe.

[0055] Step 5: The fiber piezoelectric cylinder scanning probe collects the CARS, SHG, and TPEF signal lights generated by the sample. The cladding of the second input / output hollow anti-resonant fiber receives the CARS, SHG, and TPEF signal lights reflected back by the fiber piezoelectric cylinder scanning probe, and the first fiber input / output coupler collimates and outputs them back to the device.

[0056] Step 6: The second long-pass dichroic mirror separates the nonlinearly excited optical pulses and the reflected-back CARS, SHG, and TPEF signal lights. After the third long-pass dichroic mirror separates the reflected-back CARS signal light, the first single-photon detector converts the CARS signal light into an electrical signal; after the fourth long-pass dichroic mirror separates the SHG signal light, the second single-photon detector converts the SHG signal light into an electrical signal; the third mirror turns the TPEF signal light, and the third single-photon detector converts the TPEF signal light into an electrical signal. If the fiber piezoelectric cylinder scanning probe is switched to a fiber MEMS scanning probe, the steps become:

[0057] Step 6: The second long-pass dichroic mirror separates the nonlinearly excited optical pulses and the reflected-back CARS, SHG, and TPEF signal lights. After the third long-pass dichroic mirror separates the reflected-back CARS signal light, the first single-photon detector converts the CARS signal light into an electrical signal; after the fourth long-pass dichroic mirror separates the SHG signal light, the second single-photon detector converts the SHG signal light into an electrical signal; the third mirror turns the TPEF signal light, and the third single-photon detector converts the TPEF signal light into an electrical signal. If the fiber piezoelectric cylinder scanning probe is switched to a fiber MEMS scanning probe, the steps become:

[0058] Step 1: The first input single-mode polarization-maintaining fiber accesses the S-polarized picosecond nonlinear excitation optical pulse with a wavelength of 1015 - 1070 nm output from a 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 nonlinear excitation optical pulse with a wavelength of 740 - 862 nm output from a 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 nonlinear excitation optical pulse with a wavelength of 780 nm output from a femtosecond laser, and the pulse width is 80 fs to 200 fs.

[0059] Step 2: The first fiber input collimator collimates the optical pulse accessed by the first input single-mode polarization-maintaining fiber, the second fiber input collimator collimates the optical pulse accessed by the second input single-mode polarization-maintaining fiber, and the third fiber input collimator collimates the optical pulse accessed by the first input hollow anti-resonant fiber.

[0060] Step 3: After the first mirror turns the traveling direction of the 780-nm P-polarized nonlinear excitation femtosecond optical pulse, the polarization beam splitter prism combines the 740 - 862-nm S-polarized picosecond optical pulse and the 780-nm P-polarized nonlinear excitation femtosecond optical pulse; the first long-pass dichroic mirror combines the two nonlinear excitation picosecond optical pulses and one nonlinear excitation femtosecond optical pulse.

[0061] 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 nonlinear excitation picosecond and nonlinear excitation femtosecond optical pulses into the air core of the second input-output hollow anti-resonant fiber. The second input-output hollow anti-resonant fiber transmits the nonlinear excitation optical pulse from end a into the fiber MEMS scanning probe.

[0062] Step 5: The fiber MEMS scanning probe collects the CARS, SHG, and TPEF signal lights generated by the sample, enters from end b into the input-output large-core fiber, and the input-output large-core fiber receives the reflected CARS, SHG, and TPEF signal lights, and is collimated and emitted back to the device by the first fiber input-output coupler.

[0063] Step 6: The second mirror is driven by the electric displacement stage to rotate 135 degrees, reflects the signal light transmitted back by the fiber MEMS scanning probe, after the third long-pass dichroic mirror separates the reflected CARS signal light, the first single-photon detector converts the CARS signal light into an electrical signal; after the fourth long-pass dichroic mirror separates the SHG signal light, the second single-photon detector converts the SHG signal light into an electrical signal; the third mirror turns the TPEF signal light, and the third single-photon detector converts the TPEF signal light into an electrical signal.

[0064] Step 6: The second mirror is driven by the electric displacement stage to rotate 135 degrees, reflects the signal light transmitted back by the fiber MEMS scanning probe, after the third long-pass dichroic mirror separates the reflected CARS signal light, the first single-photon detector converts the CARS signal light into an electrical signal; after the fourth long-pass dichroic mirror separates the SHG signal light, the second single-photon detector converts the SHG signal light into an electrical signal; the third mirror turns the TPEF signal light, and the third single-photon detector converts the TPEF signal light into an electrical signal.

[0065] Furthermore, the P-polarized light of the third path can be appropriately expanded or its wavelength can be changed.

[0066] Furthermore, the S polarization state and the P polarization state mainly consider the characteristics that the P light of the PBS (polarizing beam splitter prism) in the system passes through and the S light is reflected at 45°.

[0067] 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, and any changes to the present invention fall within the protection scope of the present invention application.

Claims

1. An optical fiber CARS type nonlinear multimodal micro beam splitting and combining device, characterized in that, The fiber-optic CARS-type non-linear multi-modal micro beam splitter / combiner 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 mirror, a secondary beam splitting unit, a conversion unit, 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, and 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 CARS 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 CARS signal light, SHG signal light, and TPEF signal light 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, and separates the non-linear excitation light pulse and the CARS, SHG, and TPEF signal lights through the second long-pass dichroic mirror; the second mirror switches the CARS signal light, SHG signal light, and TPEF signal lights transmitted backward; the secondary beam splitting unit separates the CARS signal light and the SHG signal light, and turns the TPEF signal light; the conversion unit converts the CARS signal light, SHG signal light, and TPEF signal lights into electrical signals.

2. The fiber optic CARS type nonlinear multimodal 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 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 the first mirror 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 optic CARS type non-linear multi-modal micro beam splitting and combining device according to claim 1, wherein The first input single-mode polarization-maintaining optical fiber accesses the S-polarized picosecond non-linear excitation light pulse with a wavelength of 1015 - 1070 nm output by a dual-output dual-wavelength picosecond laser, and the pulse width is 1 ps to 20 ps; the second input single-mode polarization-maintaining optical fiber accesses the S-polarized picosecond non-linear excitation light pulse with a wavelength of 740 - 862 nm output by a dual-output dual-wavelength picosecond laser, and the pulse width is 1 ps to 20 ps; the first input hollow anti-resonant optical fiber accesses the P-polarized femtosecond non-linear excitation light pulse with a wavelength of 780 nm output by a femtosecond laser, and the pulse width is 80 fs to 200 fs.

4. A fiber optic CARS type non-linear multimodal 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, a fourth long-pass dichroic mirror, and a third reflector. The CARS signal light is separated by the third long-pass dichroic mirror, the SHG signal light is separated by the fourth long-pass dichroic mirror, and the TPEF signal light is turned by the third reflector.

5. The fiber optic CARS type 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 CARS signal light, SHG signal light, and TPEF signal light into electrical signals in three paths.

6. The fiber optic CARS type non-linear multi-modal micro beam splitting and combining device according to claim 1, characterized in that, The second reflector switches and reflects the returned CARS signal light, SHG signal light, and TPEF signal light through angular position control.

7. The fiber optic CARS type nonlinear multimodal 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. The fiber CARS-type nonlinear multimodal micro beam splitting and combining device according to claim 5, characterized in that, In the optical fiber piezoelectric cylinder scanning probe mode, the input / output coupling unit includes a path of optical fiber input / output coupler and input / output hollow anti-resonant optical fiber, and a suspended optical fiber input / output coupler and input / output hollow anti-resonant optical fiber. The position of the second reflector is controlled to change the CARS signal light, SHG signal light, and TPEF signal light reflected back to this path of optical fiber input / output coupler.

9. The fiber optic CARS type nonlinear multimodal micro beam splitting and combining device according to claim 5, characterized in that, In the optical fiber MEMS scanning probe mode, the input / output coupling unit includes two paths of optical fiber input / output couplers and input / output hollow anti-resonant optical fiber. The position of the second reflector is controlled to change the CARS signal light, SHG signal light, and TPEF signal light reflected back to a path of optical fiber input / output coupler connected to the output end of the optical fiber MEMS scanning probe.

10. A fiber optic CARS-type non-linear multi-modal micro beam splitting and combining method implemented by using a fiber optic CARS-type non-linear multi-modal micro beam splitting and combining device according to any one of claims 1 to 7, characterized in that, The method includes the following steps: S1, Access the 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 CARS signal light, SHG signal light, and TPEF signal light, and collimate and output them back; S3, Perform primary beam splitting to separate the nonlinear excitation light pulse and the CARS, SHG, and TPEF signal lights output and returned; S3, Switch the CARS signal light, SHG signal light, and TPEF signal light transmitted backward; S4, Perform secondary beam splitting to separate the CARS signal light, separate the SHG signal light, and turn the TPEF signal light; S5, Convert the CARS signal light, SHG signal light, and TPEF signal light into electrical signals.

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