CN106532426A - Enhancing device for multiphoton imaging signal - Google Patents

Abstract

The present invention is applicable to the field of optical imaging technology, and provides a multiphoton imaging signal enhancement device, including a pulse generation unit, which is used to generate a pump pulse with a preset repetition frequency and pulse width to enter the soliton generation unit; the soliton generation unit, It is used to adjust the incident pump pulse to the pump pulse of the preset polarization state and perform polarization multiplexing processing, and generate the soliton self-frequency shift phenomenon to obtain two beams of high-energy solitons with the same wavelength and orthogonal polarization, and then combine the two A beam of high-energy solitons is incident on the soliton filter unit; the soliton filter unit is used to filter the incident two beams of high-energy solitons, and the solitons with preset wavelengths are obtained as excitation signals and sent to the laser scanning microscope system, so that the laser A scanning microscope system performs multiphoton imaging according to the excitation signal. Through the enhancing device provided by the invention, the repetition frequency of the soliton can be increased by using the polarization multiplexing technology, so as to improve the signal level of the multiphoton imaging signal.

Description

A device for enhancing multiphoton imaging signal

technical field

The invention belongs to the technical field of optical imaging, in particular to a device for enhancing multiphoton imaging signals.

Background technique

Soliton self-frequency shift is based on the nonlinear optical effect of intra-pulse stimulated Raman scattering, and it is an effective method to generate wavelength-tunable femtosecond pulses. Many optical waveguides (mainly optical fibers) with anomalous dispersion can be used to generate soliton self-frequency shifts, such as standard single-mode fibers, index-guided photonic crystal fibers, hollow-core photonic bandgap fibers, large-mode-field fibers, and large-mode-field photonic crystal rod. Standard single-mode fibers based primarily on the intrinsic dispersion properties of optical materials (such as fused silica fibers and fluoride fibers) can generate solitons with nanojoule energies. The index-guided photonic crystal fiber can be customized to any zero-dispersion wavelength, so the solitons generated can cover a wider wavelength band, but the soliton energy can only reach the sub-nanojoule level. Hollow-core photonic bandgap fibers can also be customized to any zero-dispersion wavelength, and the generated soliton energy can reach the order of microjoules, but the attenuation increases significantly near the edge of the passband, so the soliton wavelength tuning range is only tens of nanometers. The large mode field fiber and photonic crystal rod have the characteristics of broadband wavelength tuning range (hundreds of nanometers) and high soliton pulse energy (over 100 nanojoules), but the wavelength of solitons can only be greater than 1.3 due to the material dispersion of fused silica. Microns.

Multiphoton imaging requires wavelength-tunable femtosecond laser pulses as the excitation light source, and soliton self-frequency shift technology has become one of the ideal options for multiphoton imaging. Using the self-frequency shift of the soliton in the photonic crystal rod can obtain high-energy solitons in the 1700 nm band. Using the soliton light source as the excitation light source, and the background-suppressed three-photon microscopic imaging technology, the maximum imaging can be obtained in the brain of living mice depth to clearly reveal subcortical structures. Before the technology was demonstrated, multiphoton imaging at such depths required highly invasive techniques, such as removing gray matter above tissue or inserting an endoscope into the brain.

The applicant finds in the process of implementing the present invention that, so far, the imaging depth (about 1.4 mm) of the 1700 nanometer waveband is mainly limited by the signal level generated in the deep tissue, so how to enhance the signal level more effectively is to improve The key to imaging depth. From the perspective of the excitation light source, the following two technologies are mainly used at present: (1) Using a photonic crystal rod with a larger core size to carry out soliton self-frequency shifting. Because the soliton energy is directly proportional to the effective mode field area, the larger the core size, the higher the soliton energy. The two-photon and three-photon signals can be obtained by the formulas S ₂ ∝E ² f/τ and S ₃ ∝E ³ f/τ ² , where E represents the pulse energy, f represents the pulse repetition frequency, and τ represents the pulse width. It can be seen that the signal can be enhanced by the core size. (2) Dispersion compensation, that is, to compress the soliton pulse width on the sample to the minimum value. According to the above formula, it can be seen that the signal level will also increase accordingly.

The technique of increasing the core size to obtain higher soliton energies is ultimately limited by the damage threshold. Both bulk damage effects from high peak light intensities and self-focusing effects beyond the critical threshold of self-focusing of fused silica fibers (approximately 4 mW) can cause damage to photonic crystal rods or fibers.

Contents of the invention

The technical problem to be solved by the present invention is to provide a multi-photon imaging signal enhancement device, aiming at improving the signal level of the multi-photon imaging signal.

The present invention is achieved in this way, a multi-photon imaging signal enhancement device, including a pulse generating unit, a soliton generating unit and a soliton filtering unit:

The pulse generation unit is configured to generate pump pulses with a preset repetition frequency and pulse width, and inject the pump pulses into the soliton generation unit;

The soliton generation unit is configured to adjust the incident pump pulses to pump pulses of a preset polarization state and then perform polarization multiplexing processing, and generate two soliton self-frequency shift phenomena according to the processed pump pulses to obtain two beams high-energy solitons with the same wavelength and orthogonal polarization, and injecting two beams of the high-energy solitons into the soliton filter unit;

The soliton filtering unit is used to filter the incident two beams of high-energy solitons to obtain solitons with preset wavelengths, and send the processed solitons as excitation signals to the laser scanning microscope system, so that the laser scanning The microscopic system performs multiphoton imaging according to the excitation signal.

Further, the pulse generation unit includes a 1550nm fiber laser and a first silver mirror;

The 1550nm fiber laser is used to generate a pump pulse with a repetition rate of 1 MHz and a pulse width of 500 femtoseconds, and inject the pump pulse into the first silver mirror;

The first silver mirror reflects the incident pump pulse into the soliton generating unit.

Further, the soliton generation unit includes a pulse adjustment module and a soliton generation module;

The pulse adjustment module is configured to adjust the incident pump pulses to pump pulses of a preset polarization state and perform polarization multiplexing processing, and then inject the processed pump pulses into the soliton generation module;

The soliton generation module is used to generate soliton self-frequency shift phenomenon according to the incident processed pump pulse, obtain two beams of high-energy solitons with the same wavelength and orthogonal polarization, and combine the two beams of high-energy solitons incident to the soliton filter unit.

Further, the pulse adjustment module includes a first half-wave plate, a second silver mirror, a third silver mirror, a fourth silver mirror, a first polarization beam splitting cube, a second polarization beam splitting cube and a first lens;

The first half-wave plate is used to adjust the polarization state of the incident pump pulse, and incident the adjusted pump pulse to the second silver mirror;

The second silver mirror is used to reflect the incident pump pulse after polarization adjustment into the first polarization beam splitting cube;

The first polarization beam-splitting cube divides the incident pump pulse into a first pump sub-pulse and a second pump sub-pulse, and injects the second pump sub-pulse into the second polarization beam-splitting cube;

The first pump sub-pulse is respectively incident on the second polarization beam splitting cube perpendicular to the second pump sub-pulse after the optical path is adjusted by the third silver mirror and the fourth silver mirror;

The second polarization beam-splitting cube is used to combine the incident first pump sub-pulse and the second pump sub-pulse to generate 1550 nm orthogonally polarized pump pulses that are transmitted collinearly, and the common The 1550 nm orthogonally polarized pump pulse transmitted by the line is incident on the first lens;

The first lens is used to focus the incident collinearly transmitted 1550 nm orthogonally polarized pump pulses, and inject the focused pump pulses into the soliton generation module.

Further, the soliton generating module is a non-polarization-maintaining photonic crystal rod with a core diameter of 100 microns.

Further, the soliton generation unit also includes an optical path adjustment module and a soliton generation module;

The optical path adjustment module is configured to adjust the incident pump pulse to a pump pulse of a preset polarization state, and inject the pump pulse after polarization state adjustment to the soliton generation module;

The soliton generation module is used to perform polarization multiplexing processing on the incident pump pulses after the adjustment of the polarization state, and then generate a soliton self-frequency shift phenomenon according to the processed pump pulses to obtain two beams with the same wavelength and orthogonal polarization high-energy solitons, and inject two beams of the high-energy solitons into the soliton filtering unit.

Further, the optical path adjustment module includes a second half-wave plate, a fifth silver mirror and a second lens;

The second half-wave plate is used to adjust the polarization state of the pump pulse incident by the pulse generating unit, and incident the adjusted pump pulse to the fifth silver mirror;

The fifth silver mirror is used to reflect the incident polarization-adjusted pump pulse into the second lens;

The second lens is used to focus the incident pump pulse, and inject the focused pump pulse into the soliton generating module.

Further, the soliton generating module is a polarization-maintaining large-mode-field optical fiber with a core diameter of 40 microns.

Further, the soliton filtering unit includes a third lens and a filter;

The third lens is used to collimate the incident divergent two beams of soliton pulses, so that the two beams of solitons are incident on the filter in parallel;

The optical filter is used to filter the parallel solitons to obtain solitons with preset wavelengths, and send the solitons obtained after filtering to the laser scanning microscope system as excitation signals.

Further, the filter is a long-wave pass filter.

Compared with the prior art, the present invention has the beneficial effect that: the embodiment of the present invention generates a pump pulse with a preset repetition frequency and pulse width, and adjusts the polarization state of the pump pulse, and the pump pulse after the polarization state adjustment is adjusted. The pump pulses are subjected to polarization multiplexing processing, and two beams of solitons with the same wavelength and orthogonal polarization are obtained due to the soliton self-frequency shift phenomenon, and the obtained two beams of solitons are filtered, and the processed solitons are sent to the laser scanning as excitation signals A microscopic system, enabling the laser scanning microscopic system to perform multiphoton imaging according to the excitation signal. Through the enhancement device provided by the embodiment of the present invention, the repetition frequency of the soliton can be increased by using the polarization multiplexing technology, so as to improve the signal level of the multiphoton imaging signal.

Description of drawings

FIG. 1 is a schematic structural diagram of a multiphoton imaging signal enhancement device provided by the first embodiment of the present invention;

Fig. 2 is a detailed structural schematic diagram of a multiphoton imaging signal enhancement device provided by the second embodiment of the present invention;

Fig. 3 is the measured spectrum and the interference autocorrelation trace of the horizontally polarized state and the vertically polarized state soliton in the non-polarization-maintaining photonic crystal rod provided by the second embodiment of the present invention;

Fig. 4 is a three-photon fluorescence imaging diagram in a non-polarization-maintaining photonic crystal rod provided by the second embodiment of the present invention;

Fig. 5 is a detailed structural schematic diagram of a multiphoton imaging signal enhancement device provided by the third embodiment of the present invention;

Fig. 6 is the measured spectrum and interference autocorrelation trace of horizontal polarization state and vertical polarization state soliton in the polarization maintaining large mode field fiber provided by the third embodiment of the present invention;

Fig. 7 is a diagram of two-photon fluorescence imaging in a polarization-maintaining large mode field fiber provided by the third embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The applicant of the present invention found in the process of implementing the present invention that the technology of increasing the fiber core size to obtain greater soliton energy will eventually be limited by the damage threshold. Once the maximum soliton energy is limited by the damage threshold, the soliton pulse width will also be limited. Due to the dispersion compensation, the minimum value is reached. To enhance the multiphoton imaging signal, the only controllable laser parameter is the repetition frequency. Because the multiphoton imaging signal is proportional to the repetition frequency, the increase of the repetition frequency can also effectively improve the multiphoton signal. Signal level, based on this, the present invention provides a multiphoton imaging signal enhancement device as shown in Figure 1, including a pulse generating unit 1, a soliton generating unit 2, and a soliton filtering unit 3:

A pulse generating unit 1, configured to generate pump pulses with preset repetition frequency and pulse width, and inject the pump pulses into the soliton generating unit 2;

The soliton generating unit 2 is used to adjust the incident pump pulse to a pump pulse of a preset polarization state and perform polarization multiplexing processing, and generate a soliton self-frequency shift phenomenon according to the processed pump pulse to obtain two beams of the same wavelength and orthogonally polarized high-energy solitons, and inject two beams of the high-energy solitons into the soliton filter unit 3 .

The soliton filtering unit 3 is used to filter the incident two beams of high-energy solitons to obtain solitons with preset wavelengths, and send the processed solitons as excitation signals to the laser scanning microscope system, so that the laser scanning The microsystem performs multiphoton imaging according to the excitation signal.

Through the enhancement device provided by the embodiment of the present invention, the repetition frequency of the soliton can be increased by using the polarization multiplexing technology, so as to improve the signal level of the multiphoton imaging signal. In this embodiment, the enhancement device uses polarization multiplexing technology to combine two beams of orthogonally polarized pulses together in space (but they are separated in time due to delay), so the repetition rate of a beam of pulses is becomes two times, and the two beams of orthogonally polarized solitons are combined together in space due to the self-frequency shift of the soliton.

On the basis of the first embodiment, the present invention provides the second embodiment shown in Fig. 2, wherein: pulse generation unit 1 comprises 1550 nanometer fiber lasers Fiber Laser and the first silver mirror M1; 1550 nanometer fiber lasers Fiber Laser, uses To generate a pump pulse with a repetition rate of 1 MHz and a pulse width of 500 femtoseconds, and inject the pump pulse into the first silver mirror M1, the pump pulse is a 1550 nanometer linearly polarized pump pulse; the first silver The mirror M1 reflects the incident pump pulse, and then enters the soliton generating unit 2 .

The soliton generation unit 2 includes a pulse adjustment module 21 and a soliton generation module 22;

A pulse adjustment module 21, configured to adjust the incident pump pulses to pump pulses of a preset polarization state and perform polarization multiplexing processing, and then inject the processed pump pulses into the soliton generation module 22;

The soliton generation module 22 is used to generate the soliton self-frequency shift phenomenon according to the incident processed pump pulse, obtain two beams of high-energy solitons with the same wavelength and orthogonal polarization, and inject the two beams of high-energy solitons to the soliton filter unit 3.

The pulse adjustment module 21 includes a first half-wave plate HWP1, a second silver mirror M2, a third silver mirror M3, a fourth silver mirror M4, a first polarization beam splitting cube PBS1, a second polarization beam splitting cube PBS2 and a first lens L1 ;

The first half-wave plate HWP1 is used to adjust the polarization state of the incident pump pulse, and the adjusted pump pulse is incident on the second silver mirror M2; the adjusted pump pulse passes through the second silver mirror M2 After reflection, it is incident on the first polarization beam-splitting cube PBS1; the first polarization beam-splitting cube PBS1 divides the incident pump pulse into a first pump sub-pulse and a second pump sub-pulse, and the second pump sub-pulse The pulse is incident on the second polarization beam-splitting cube PBS2; the first pump sub-pulse is adjusted to the optical path by the third silver mirror M3 and the fourth silver mirror M4 respectively, and is perpendicular to the second pump sub-pulse to enter the second polarization The beam-splitting cube PBS2; the second polarization beam-splitting cube PBS2 is used to combine the incident first pump sub-pulse and the second pump sub-pulse to generate a collinearly transmitted 1550 nm orthogonally polarized pump pulse, and The collinearly transmitted 1550 nm orthogonally polarized pump pulses are incident to the first lens L1; the first lens L1 is used to focus the collinearly transmitted 1550 nm orthogonally polarized pump pulses, And the focused pump pulse is incident to the soliton generation module 22 .

In a specific application, the soliton generation module 22 is a non-polarization-maintaining photonic crystal rod PCrod with a core diameter of 100 microns, and the non-polarization-maintaining photonic crystal rod PCrod is used to generate solitons according to the incident pump pulse after processing Due to the frequency shift phenomenon, two beams of high-energy solitons with the same wavelength and orthogonal polarization are generated, and the two beams of high-energy solitons are incident to the soliton filter unit 3 .

The soliton filtering unit 3 includes a third lens L3 and a filter LPF; the third lens L3 is used to collimate the incident divergent two beams of solitons so that the two beams of solitons are incident on the filter LPF in parallel; The slice LPF is used for filtering the parallel solitons to obtain solitons with preset wavelengths, and sending the solitons obtained after filtering as excitation signals to the laser scanning microscope system LSM. Specifically, the filter LPF is a long-wave pass filter.

In order to improve the signal level of multi-photon imaging, this embodiment provides an enhancement device that uses polarization multiplexing technology to increase the repetition frequency of soliton pulses. Polarization multiplexing technology is generally used to generate two-color light solitons in polarization-maintaining fibers. The physical principle is that the input linearly polarized pump pulse light will be divided into two beams of orthogonally polarized pump pulse light, and the two beams will be separated at different speeds. Propagate along the two main axes of the fiber respectively. Both pump pulses will generate solitons due to the phenomenon of soliton self-frequency shift. Adjusting the polarization state of the input linearly polarized pump pulse light can continuously adjust the wavelength interval of two beams of orthogonally polarized solitons. In this embodiment, the polarization multiplexing technology is applied to the enhancement device including the non-polarization-maintaining photonic crystal rod without polarization structure, which can also generate high-energy solitons with the same wavelength and orthogonal polarization. On this basis, this embodiment applies the polarization multiplexing technology to three-photon and two-photon imaging. Experimental results show that the final signal level obtained by excitation of the polarized combined beam is equal to the sum of the signals obtained by excitation of two orthogonally polarized solitons respectively. It can be seen that in multiphoton imaging, polarization multiplexing technology can improve the signal level.

In this embodiment, a 1550nm fiber laser (FLCPA-02CSZU, Calmar) with a repetition rate of 1 MHz and a pulse width of 500 femtoseconds was used as a pumping light source, which generated A pump pulse, where the pump pulse is a 1550 nanometer line polarized pump pulse. The first half-wave plate HWP is used to change the polarization state of the 1550nm line polarized pump pulse, and to adjust the energy ratio along the two orthogonal polarization directions. The used non-polarization-maintaining photonic crystal rod has a core diameter of 100 μm and a length of 44 cm (SC-1500/100-Si-ROD, NKT Photonics). This non-polarization-maintaining photonic crystal rod has no polarization-maintaining structure, but the polarization state of the laser light can remain unchanged even after a transmission length of 1 meter. Two polarization beamsplitter cubes are used to generate the 1550 nm orthogonally polarized pump pulses delivered collinearly. The 1550nm orthogonally polarized pump pulse generates the soliton self-frequency shift in the non-polarization-maintaining photonic crystal rod, and then passes through the long-wave pass filter to obtain the soliton required in this embodiment. This embodiment also uses a spectrometer (OSA203B) and an interferometric autocorrelator built for this embodiment to measure the spectrum and pulse width. Finally, the solitons after spectrometer and interferometric autocorrelator are multiphoton imaged in laser scanning microscopy (LSM).

In this embodiment, the polarization multiplexing technology is firstly applied to the non-polarization-maintaining photonic crystal rod. Figure 3 shows the spectra and interference autocorrelation traces of the filtered horizontally polarized solitons (a in Figure 3) and vertically polarized solitons (b in Figure 3). Under the condition of maximum pump energy, both solitons moved to a wavelength of 1620 nm, and the soliton energies were 73 nJ and 75 nJ, respectively. c and d in Fig. 3 show the interference autocorrelation traces of the horizontal polarization state and the vertical polarization state soliton respectively, from which the pulse width can be obtained. Assuming that the soliton is a hyperbolic secant model, after deconvolution calculation, the measured pulse widths are 73 femtoseconds and 70 femtoseconds, respectively.

A major advantage of the polarization multiplexing technique is that the two solitons propagate collinearly, which is of great benefit for multiphoton imaging, because the spatial coincidence of the two excitation beams is crucial for multiphoton imaging. In this implementation, three-photon fluorescence imaging was performed on live mouse blood vessels labeled with Texas-red dye to demonstrate the signal enhancement effect of polarization multiplexing. To quantify this signal enhancement, the average three-photon fluorescence signal intensities within the same vessel region were compared, as shown in the marked region in Figure 4, where the chromaticity bar in Figure 4 indicates the signal level, and the scale bar is 50 μm. Since the horizontal polarization state and vertical polarization state solitons have similar energy and pulse width, the signal values generated are also approximately equal, which are 28390 and 27970 respectively. When two solitons are simultaneously incident on the sample for three-photon fluorescence excitation, the signal value is 56980, which is basically equal to the sum of the signal values when the two solitons are excited separately. Therefore, the polarization multiplexing technique in non-PM photonic crystal rods can effectively improve the multiphoton imaging signal. It should also be noted that in front of the non-polarization-maintaining photonic crystal rod, the transmittance of the polarization multiplexing system composed of two 1550nm polarization beam-splitting cubes and two silver mirrors is as high as 94%.

In practical applications, there are also polarization-maintaining photonic crystal rods. The polarization multiplexing technology in this large mode field optical waveguide is easier to implement. In order to imitate this polarization-maintaining photonic crystal rod, the present invention also provides another embodiment as shown in FIG. The specific structure of the soliton generating unit 2 is different, wherein:

The soliton generation unit 2 also includes an optical path adjustment module 23 and a soliton generation module 24;

An optical path adjustment module 23, configured to adjust the incident pump pulse to a pump pulse of a preset polarization state, and inject the pump pulse after polarization state adjustment to the soliton generation module 24;

The soliton generation module 24 is used to perform polarization multiplexing processing on the incident pump pulses after the adjustment of the polarization state, and then generate a soliton self-frequency shift phenomenon according to the processed pump pulses to obtain two beams of the same wavelength and orthogonal polarization. high-energy solitons, and inject two beams of the high-energy solitons into the soliton filtering unit 3 .

The optical path adjustment module 23 includes a second half-wave plate HWP2, a fifth silver mirror M5 and a second lens L2; the second half-wave plate HWP2 is used to adjust the polarization state of the incident pump pulse, and the adjusted pump pulse The pulse is incident on the fifth silver mirror M5; the pump pulse after polarization adjustment is reflected by the fifth silver mirror M5, and then incident on the second lens L2; the second lens L2 is used to focus the incident pump pulse, and The focused pump pulse is incident to the soliton generation module 24 .

The soliton generation module 24 is a polarization-maintaining large-mode-field optical fiber LMA Fiber; the polarization-maintaining large-mode-field optical fiber LMA Fiber is used to perform polarization multiplexing processing on the incident polarization state-adjusted pump pulses, and then according to the processed pump pulses The soliton self-frequency shift phenomenon is generated, two beams of high-energy solitons with the same wavelength and orthogonal polarization are generated, and the two beams of high-energy solitons are incident to the soliton filter unit 3 .

In Fig. 5, a polarization-maintaining large-mode-field fiber LMA Fiber with a core diameter of 40 microns is used. In the enhancement device provided in this embodiment, it is only necessary to add a half-wave plate HWP2 in front of the polarization-maintaining large-mode-field fiber LMA Fiber, and the generated orthogonally polarized solitons will respectively travel along the polarization-maintaining large-mode-field fiber LMA Fiber The two axes of propagation. Compared with non-PM photonic crystal rods, the filtered solitons produced by PM-LMF will have more obvious modulation spectra (a and b in Fig. 6), and interferometric autocorrelation traces (Fig. 6 c and d). In this embodiment, two pump pulses or solitons undergo cross-phase modulation during transmission, which is different from the situation in non-PM photonic crystal rods, where the polarization beam-splitting cube introduces The optical delay is reduced so that the two orthogonally polarized pump pulses are completely separated in time. The energies of the filtered horizontally polarized and vertically polarized solitons are 17.1 nJ and 19.6 nJ, respectively. After deconvolution calculation, the measured pulse widths of horizontally polarized solitons and vertically polarized solitons are 71 femtoseconds and 74 femtoseconds, respectively.

Similarly, in this embodiment, the polarization multiplexing technology is used in the polarization-maintaining large mode field fiber, and multi-photon imaging comparison is carried out to prove the effect of this technology on signal enhancement. In this example, the two-photon fluorescence signals of the tail tendon of mice were compared to prove the applicability of this technique to different imaging modalities. The signal values generated by horizontally polarized soliton excitation light (Fig. 7a) and vertically polarized soliton excitation light (Fig. 7b) are 22340 and 27070, respectively. In Fig. 7, the chromaticity bar indicates the signal level, and the scale is 50 microns. The signal value obtained by simultaneous excitation of two solitons is enhanced to 51600. This shows that polarization multiplexing can also enhance the signal level of multiphoton imaging signals using polarization-maintaining large-mode-field fibers.

In order to improve the signal level of the multi-photon imaging signal, the present invention provides the above embodiment, wherein the imaging signal is excited by the optical soliton generated due to the self-frequency shift of the soliton in the large mode field area optical waveguide. Compared with single-polarized light soliton excitation, polarization multiplexing technology actually doubles the repetition frequency of solitons, thereby increasing the signal proportionally. This technology can be applied to polarization-maintaining photonic crystal rods in addition to non-polarization-maintaining photonic crystal rods and polarization-maintaining large-mode-field fibers. The multiphoton imaging results of the two modes of three-photon fluorescence imaging and two-photon fluorescence imaging are consistent with the results of this embodiment, that is, polarization multiplexing can improve the signal level of multiphoton imaging signals. In the application of non-PM photonic crystal rods, the more pairs of polarization beam-splitting cubes can be added, the repetition rate of solitons will increase proportionally. For example, adding a pair of polarization beam-splitting cubes will additionally increase the repetition rate by two times, and the multi-photon imaging signal will also increase by two times, and the total transmittance will be higher, because each pair of polarization beam-splitting cubes has only Added 6% loss. In addition, the output solitons from non-PM photonic crystal rods are collinear, which is convenient for subsequent multiphoton imaging.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (10)

1. a kind of intensifier of multi-photon imaging signal, it is characterised in that including impulse generating unit, orphan's generation unit and Orphan's filter unit：

The impulse generating unit, for producing the pumping pulse of preset repetition rate and pulsewidth, and the pumping pulse is entered It is incident upon orphan's generation unit；

Orphan's generation unit, is carried out for the incident pumping pulse is adjusted to after the pumping pulse of preset polarization state Palarization multiplexing process, and soliton self-frequency sh phenomenon is produced according to the pumping pulse after process obtain two beam phase co-wavelengths and orthogonal The high-energy orphan of polarization, and high-energy orphan described in two beams is incident to into orphan's filter unit；

Orphan's filter unit, for being filtered process to two incident beam high-energy orphans, obtains the orphan of preset wavelength Son, and the orphan after process is sent to into laser scanning microscope system as excitation signal, so that the scan laser microphotograph system System carries out multi-photon imaging according to the excitation signal.

2. intensifier as claimed in claim 1, it is characterised in that the impulse generating unit includes that 1550 nano optical fibers swash Light device and the first silver mirror；

The 1550 nano optical fibers laser instrument, for producing the pumping pulse of 1 MHz repetition and 500 femtosecond pulsewidths, and The pumping pulse is incident to into first silver mirror；

First silver mirror reflects incident pumping pulse into orphan's generation unit.

3. intensifier as claimed in claim 1 or 2, it is characterised in that orphan's generation unit includes pulse adjustment mould Block and orphan's generation module；

The pulse adjusting module, for the incident pumping pulse to be adjusted to the pumping pulse of preset polarization state and carry out Then pumping pulse after process is incident to orphan's generation module by palarization multiplexing process；

Orphan's generation module, for producing soliton self-frequency sh phenomenon according to the pumping pulse after the incident process, obtains To two beam phase co-wavelengths and cross-polarization high-energy orphan, and high-energy orphan described in two beams is incident to into orphan filter Ripple unit.

4. intensifier as claimed in claim 3, it is characterised in that the pulse adjusting module include the first half-wave plate, Two silver mirrors, the 3rd silver mirror, the 4th silver mirror, the first polarizing beam splitter cube, the second polarizing beam splitter cube and the first lens；

First half-wave plate is used for the polarization state of the pumping pulse for adjusting incidence, and will be the pumping pulse after adjustment incident To second silver mirror；

Second silver mirror is reflected into first polarization beam splitting cube for the pumping pulse after incident polarization state is adjusted Body；

Incident pumping pulse is divided into the first pumping subpulse and the second pumping subpulse by first polarizing beam splitter cube, And the second pumping subpulse is incident to into second polarizing beam splitter cube；

The first pumping subpulse is after described in, the 3rd silver mirror and the 4th silver mirror carry out light path adjustment respectively, with second pump Pu subpulse vertical incidence is to second polarizing beam splitter cube；

Second polarizing beam splitter cube for the first incident pumping subpulse and the second pumping subpulse are carried out conjunction beam, Produce the pumping pulse of 1550 nanometers of cross-polarizations of conllinear transmission, and by 1550 nanometers of cross-polarizations of the conllinear transmission Pumping pulse is incident to first lens；

First lens for being focused to the pumping pulse of 1550 nanometers of cross-polarizations of incident described conllinear transmission, And the pumping pulse after focusing is incident to into orphan's generation module.

5. intensifier as claimed in claim 4, it is characterised in that it is 100 micro- that orphan's generation module is core diameter The sub- crystal bar of non-guarantor's polarisation of rice.

6. intensifier as claimed in claim 1 or 2, it is characterised in that orphan's generation unit is also adjusted including light path There is module in module and orphan；

The light path adjusting module, for the incident pumping pulse to be adjusted to the pumping pulse of preset polarization state, and will Pumping pulse after polarization state adjustment is incident to the orphan and module occurs；

There is module in the orphan, for carrying out palarization multiplexing process to the pumping pulse after incident polarization state adjustment, then Soliton self-frequency sh phenomenon is produced according to the pumping pulse after process, the high-energy for obtaining two beam phase co-wavelengths and cross-polarization is lonely Son, and high-energy orphan described in two beams is incident to into orphan's filter unit.

7. intensifier as claimed in claim 6, it is characterised in that the light path adjusting module include the second half-wave plate, Five silver mirrors and the second lens；

Second half-wave plate is used for polarization state of the adjustment by the incident pumping pulse of the impulse generating unit, and will adjust Pumping pulse after whole is incident to the 5th silver mirror；

5th silver mirror is reflected into second lens for the pumping pulse after incident polarization state is adjusted；

Second lens are for being focused to incident pumping pulse, and the pumping pulse after focusing is incident to the orphan There is module in son.

8. intensifier as claimed in claim 7, it is characterised in that the orphan occurs module to protect mould field optical fiber bigger than normal.

9. intensifier as claimed in claim 1, it is characterised in that orphan's filter unit includes the 3rd lens and optical filtering Piece；

3rd lens, for two beam soliton pulses of incident diverging are collimated so that the two beams orphan is parallel It is incident to the optical filter；

The optical filter, for being filtered process to the parallel orphan, obtains the orphan of preset wavelength, and by filtering The orphan obtained after reason is sent to laser scanning microscope system as excitation signal.

10. intensifier as claimed in claim 9, it is characterised in that the optical filter is long wave pass filter.