A tunable high-repetition-rate high-power multi-wavelength optical pulse generation system

Abstract

The application discloses a tunable high-repetition-frequency high-power multi-wavelength optical pulse generation system, which belongs to the technical field of optoelectronic devices and has the structure that the output end of a seed pulse source (1) is connected with the input end of a repetition frequency multiplication module (2), the output end of the repetition frequency multiplication module (2) is connected with the input end of a shaping optical path module (3), the output end of the shaping optical path module (3) is connected with the input end of a power amplification module (4), and the output end of the power amplification module (4) is connected with the input end of a pulse compression module (5). The application designs a multi-wavelength pulse seed source by using multiple hybrid filters, and realizes tunable multi-wavelength, high-repetition-frequency, high-power narrow pulse output by using an MZI-Sagnac hybrid repetition frequency multiplication structure and other technologies.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optoelectronic devices, and particularly relates to a tunable high-repetition high-power multi-wavelength optical pulse generation system. BACKGROUND

[0002] With the rapid development of laser technology, ultra-short pulse lasers have become the core tool of modern photonics research, which shows great application potential in the fields of precision spectroscopy, optical frequency comb, laser processing, biomedical imaging and next-generation optical communication systems. Among them, the ultra-short pulse light source capable of simultaneously generating multiple wavelengths is widely favored by researchers because it can obtain multi-dimensional information or process multiple channels in a single measurement.

[0003] At present, the technical route to realize multi-wavelength pulse output mainly relies on multi-wavelength fiber lasers. The traditional method is to introduce frequency-selective elements such as Sagnac ring mirrors, Lyot filters, and Mach-Zehnder interferometers into the laser resonant cavity, and through the periodic filtering characteristics of these elements, multiple wavelengths of laser oscillation are excited within the gain medium bandwidth. However, such lasers based on linear filtering mechanism are generally limited by strong mode competition and uniform broadening effect in optical fibers, resulting in low output power and poor wavelength stability, especially in room temperature environment, it is difficult to obtain stable continuous wave output, not to mention stable mode-locked pulse output.

[0004] In order to overcome mode competition, researchers have developed multi-wavelength laser technology assisted by nonlinear effects, such as using nonlinear polarization rotation or nonlinear optical ring mirror to realize mode-locking, and combining the characteristics of erbium-doped fiber gain medium, relatively stable multi-wavelength pulse sequence can be obtained at room temperature. However, these systems have the following inherent limitations: first, the repetition frequency is low, mostly in the order of megahertz, because it is limited by the physical length of the resonant cavity, high repetition frequency often means short cavity length, which will sacrifice single pulse energy and increase mode-locking difficulty; second, the output power is limited, as an oscillator directly output, its pulse energy is usually below nanojoule, which is difficult to meet the needs of many applications requiring high photon flux or strong nonlinear interaction; third, the wavelength tuning ability is insufficient and coupled with power and repetition frequency parameters, the traditional tuning method such as adjusting the polarization state in the filter often affects the mode-locking state and output power at the same time, resulting in complex tuning process and unstable output performance.

[0005] To improve the repetition frequency, the prior art usually adopts an off-cavity repetition frequency multiplication scheme, for example, using a Mach-Zehnder interferometer to perform time-domain replication and interleaving on the pulse sequence. However, a simple cascaded MZI will introduce significant insertion loss, and the multiplication process can destroy the relative timing and phase relationship between the multi-wavelength pulses, resulting in pulse waveform degradation. In order to improve the output power, a fiber amplifier needs to be cascaded after the oscillator, but this will introduce new challenges: nonlinear effects in the amplification process will broaden the spectrum, distort the pulses, and may exacerbate the gain competition between the multi-wavelengths, destroy the original multi-wavelength state, and even cause the multi-wavelength output to degrade to a single-wavelength or wavelength-switching unstable state.

[0006] In summary, there are still many challenges in obtaining high repetition frequency and high power multi-wavelength output fiber laser systems at present. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application aims to provide a tunable high repetition frequency and high power multi-wavelength optical pulse generation system. The main purpose is to solve the technical problems that the prior art cannot simultaneously realize wavelength flexible tuning, high repetition frequency and high output power, overcome the defects that multi-wavelength pulses are prone to instability in the amplification process, traditional repetition frequency multiplication technology damages pulse quality, and system parameters are coupled to each other, resulting in tuning difficulty. The initial multi-wavelength pulse is obtained by a seed pulse source, the repetition frequency of the pulse is improved by a repetition frequency multiplication module, and high power stable pulse output is obtained through a power amplification module and a pulse compression module.

[0008] The object of the present application is achieved by the following technical solutions:

[0009] The application discloses a tunable high-repetition-frequency high-power multi-wavelength optical pulse generation system, which comprises a seed pulse source 1, a repetition frequency multiplication module 2, a shaping optical path module 3, a power amplification module 4 and a pulse compression module 5; the output end of the seed pulse source 1 is connected with the input end of the repetition frequency multiplication module 2; the output end of the repetition frequency multiplication module 2 is connected with the input end of the shaping optical path module 3; the output end of the shaping optical path module 3 is connected with the input end of the power amplification module 4; the output end of the power amplification module 4 is connected with the input end of the pulse compression module 5; the seed pulse source 1 adopts a shared laser resonant cavity structure, internally parallelly integrates a Sagnac ring and a Lyot type filtering branch, utilizes a high-birefringence fiber and a polarization controller to jointly regulate and control a transmission wavelength, realizes flexible tuning of multi-wavelength output, combines a nonlinear mode-locking mechanism and a multimode saturable absorber, realizes self-starting mode-locking through nonlinear phase shift accumulation, and effectively suppresses mode competition among the multi-wavelengths; the repetition frequency multiplication module 2 is provided with an ultrashort pulse seed source which is independently tunable in wavelength and high in stability; the repetition frequency multiplication module 2 adopts a hybrid structure combining a Sagnac ring and an asymmetric MZI; the Sagnac ring is based on a polarization interference principle, pre-processes each input pulse into a pulse pair with a fixed time delay, injects the pulse pair into the asymmetric MZI, accurately controls the optical path difference of two arms, utilizes interference constructive and destructive effects, realizes time domain interleaving and synthesis of multi-channel pulses, and thus effectively improves the repetition frequency.

[0010] The structure of the seed pulse source 1 is as follows: the first pump source 101 is connected with the 980nm end of the first wavelength division multiplexer 102, the common end of the first wavelength division multiplexer 102 is connected with the input end of the first coupler 105 through the first erbium-doped fiber 103 and the first polarization-independent optical isolator 104, the 50% output end of the first coupler 105 is connected with the first polarizer 106, the optical pulse is connected with the 50% input end of the second coupler 111 after passing through the first polarizer 106, the first polarization controller 107, the first polarization-maintaining fiber 108, the second polarization controller 109 and the second polarizer 110; the other 50% output end of the first coupler 105 is connected with the 50% input end of the third coupler 112, the 50% output end of the third coupler 112 is connected with the third polarization controller 113, the third polarization controller 113 is connected with the first high-birefringence fiber 114, the first high-birefringence fiber 114 is connected with the fourth polarization controller 115, the fourth polarization controller 115 is connected with the second high-birefringence fiber 116, the second high-birefringence fiber 116 is connected with the other 50% input end of the third coupler 112, the other 50% output end of the third coupler 112 is connected with the first fiber delay line 117, the first fiber delay line 117 is connected with the other 50% input end of the second coupler 111, the optical pulse is output from the output end of the second coupler 111, passes through the fifth polarization controller 118, the extruded polarization controller 119 containing SMF-GIMF-SMF, is connected with the input end of the fourth coupler 120, the 80% output end of the fourth coupler 120 is connected with the other common end of the first wavelength division multiplexer 102, and the optical pulse is output from the 20% output end of the fourth coupler 120.

[0011] The heavy frequency multiplication module 2 has the following optical path structure: the light pulse passes through the second polarization-independent optical isolator 201, the sixth polarization controller 202, the sixth polarization controller 202 is connected with the input end of the fifth coupler 203, 50% of the output end of the fifth coupler 203 is connected with the first single-mode optical fiber 204, the first single-mode optical fiber 204 is connected with the seventh polarization controller 205, the seventh polarization controller 205 is connected with the input end of the sixth coupler 206, the output end of the sixth coupler 206 is connected with the second optical fiber delay line 209, the second optical fiber delay line 209 is connected with the eighth polarization controller 208, the eighth polarization controller 208 is connected with the third high-birefringence optical fiber 207, the third high-birefringence optical fiber 207 is connected with the other input end of the sixth coupler 206, the other output end of the sixth coupler 206 is connected with the input end of the seventh coupler 210; the other output end of the fifth coupler 203 is connected with the second single-mode optical fiber 211, the second single-mode optical fiber 211 is connected with the third optical fiber delay line 212, the third optical fiber delay line 212 is connected with the ninth polarization controller 213, the ninth polarization controller 213 is connected with the other input end of the seventh coupler 210, and finally the light pulse is output from the output end of the seventh coupler 210.

[0012] The shaping optical path module 3 has the following optical path structure: the light pulse is transmitted to the first half-wave plate 301, reflected by the first mirror 302 and the second mirror 303 and then enters the first expansion mirror 304, the light pulse passes through the first expansion mirror 304 and is reflected by the third mirror 305 to the first spatial light modulator 306, the light beam modulated by the first spatial light modulator 306 passes through the first convex lens 307, the second convex lens 308 and the non-polarization beam splitter 309, wherein one light beam passing through the non-polarization beam splitter 309 is focused by the third convex lens 310 and then enters the first feedback device 311, and the other light beam passing through the non-polarization beam splitter 309 is focused by the fourth convex lens 312 and then output after passing through the fourth mirror 313.

[0013] The power amplification module 4 has the following optical path structure: optical pulses are transmitted to the passive optical fiber 402 through the semiconductor saturable absorber mirror 401 (SESAM), the second doped erbium optical fiber 403 is connected with the input end of the first fiber Bragg grating 404, the output end of the first fiber Bragg grating 404 is connected with the common end of the second wavelength division multiplexer 405, the 980nm end of the second wavelength division multiplexer 405 is connected with the second pump source 406, the other common end of the second wavelength division multiplexer 405 is connected with the input end of the third isolator 407, the output end of the third isolator 407 outputs light which passes through the fifth mirror 408, the sixth mirror 409, the fifth convex lens 410, the sixth convex lens 411, the input mirror 412, the first Er: YAP crystal 413, the eighth coupler 414, the first band-pass filter 415, the third polarizer 416, the seventh convex lens 417, the dichroic mirror 418, the third pump source 419 is connected with the 980nm end of the third wavelength division multiplexer 420, optical pulses from the common end of the third wavelength division multiplexer 420 pass through the eighth convex lens 421, the ninth convex lens 422, the dichroic mirror 418, and after the optical pulses pass out from the dichroic mirror 418, they pass through the second Er: YAP crystal 423 and the second band-pass filter 424 and are outputted.

[0014] The pulse compression module 5 has the following optical path structure: the optical pulse is incident to the second polarizing beam splitter 502 through the first polarizing beam splitter 501, part of the optical pulse passing through the second polarizing beam splitter 502 is transmitted to the seventh mirror 503, the optical pulse is reflected by the seventh mirror 503 and then sequentially reflected by the eighth mirror 504, the ninth mirror 505 and the tenth mirror 506, the optical pulse reflected by the tenth mirror 506 is incident to the first grating 512, the first grating 512 reflects the optical pulse to the second grating 513, the second grating 513 reflects the optical pulse to the eleventh mirror 514, the optical pulse reaches the eleventh mirror 514 and is reflected back to the first grating 512 along the input route, the first grating 512 transmits the optical pulse to the twelfth mirror 515, the optical pulse is reflected by the twelfth mirror 515 to the thirteenth mirror 517, and then is incident to the tenth convex lens 535, another part of the optical pulse output from the second polarizing beam splitter 502 is transmitted to the fourteenth mirror 507, the optical pulse is reflected by the fourteenth mirror 507 and then sequentially reflected by the fifteenth mirror 508, the sixteenth mirror 509, the seventeenth mirror 510 and the eighteenth mirror 511, the optical pulse reflected by the eighteenth mirror 511 and the optical pulse reflected by the tenth mirror 506 enter the first grating 512 in parallel, the optical pulse incident to the first grating 512 from the tenth mirror 506 as described above sequentially passes through the first grating 512, the second grating 513 and the eleventh mirror 514 and returns to the first grating 512 along the input route, the optical pulse is transmitted by the first grating 512 to the twelfth mirror 515, the optical pulse is reflected by the twelfth mirror 515 to the nineteenth mirror 516, and then is incident to the tenth convex lens 535, the optical pulse is transmitted by another output end of the first polarizing beam splitter 501 to the twentieth mirror 518, is transmitted to the third polarizing beam splitter 519 through the twentieth mirror 518, part of the optical pulse passing through the third polarizing beam splitter 519 is transmitted to the twenty-first mirror 520, the optical pulse is reflected by the twenty-first mirror 520 and then sequentially reflected by the twenty-second mirror 521, the twenty-third mirror 522 and the twenty-fourth mirror 523, the optical pulse reflected by the twenty-fourth mirror 523 is incident to the third grating 529, the third grating 529 reflects the optical pulse to the fourth grating 530, the fourth grating 530 reflects the optical pulse to the twenty-fifth mirror 531, the optical pulse reaches the twenty-fifth mirror 531 and is reflected back to the third grating 529 along the input route, the third grating 529 transmits the optical pulse to the twenty-sixth mirror 532, the optical pulse is reflected by the twenty-sixth mirror 532 to the twenty-seventh mirror 534, and then is reflected by the twenty-seventh mirror 534 to the tenth convex lens 535, another part of the optical pulse output from the third polarizing beam splitter 519 is transmitted to the twenty-eighth mirror 524,The light pulse is reflected by the twenty-eighth mirror 524, and then passes through the twenty-ninth mirror 525, the thirtieth mirror 526, the thirty-first mirror 527, and the thirty-second mirror 528. The light pulse reflected by the thirty-second mirror 528 enters the third grating 529 in parallel with the light pulse reflected by the twenty-fourth mirror 523. The light pulse entering the third grating 529 from the twenty-fourth mirror 523 passes through the third grating 529, the fourth grating 530, and the twenty-fifth mirror 531 in the order described above, and returns to the third grating 529 along the input path. The light pulse is transmitted from the third grating 529 to the twenty-sixth mirror 532. The light pulse is reflected by the twenty-sixth mirror 532 to the thirty-third mirror 533, and then reflected by the thirty-third mirror 533 to the tenth convex lens 535. The four light pulses passing through the nineteenth mirror 516, the thirteenth mirror 517, the twenty-seventh mirror 534, and the thirty-third mirror 533 in parallel enter the tenth convex lens 535. The light pulses are focused by the tenth convex lens 535 and then fused. The fused light pulse is reflected by the thirty-fourth mirror 536 to the thirty-fifth mirror 537. The light pulse is transmitted from the thirty-fifth mirror 537 to the second half-wave plate 538. The light pulse is reflected by the thirty-sixth mirror 539 to the second spatial light modulator 540 after passing through the second half-wave plate 538. The light beam modulated by the second spatial light modulator 540 is focused by the eleventh convex lens 541, the twelfth convex lens 542, and the thirteenth convex lens 543, and then enters the second feedback device 544. The light pulse is transmitted from the second feedback device 544 to the thirty-seventh mirror 545, the thirty-eighth mirror 546, and the third half-wave plate 547. The light pulse is incident on the fourth polarization beam splitter 548 after passing through the third half-wave plate 547. The light pulse output from the fourth polarization beam splitter 548 in parallel along the incident direction is transmitted to the thirty-ninth mirror 549. The light pulse is reflected by the thirty-ninth mirror 549 to the fortieth mirror 550. The light pulse is reflected by the fortieth mirror 550 to the first concave mirror 552. The light pulse is incident on the second concave mirror 554 through the LBO crystal 553 after passing through the first concave mirror 552. The light pulse is incident on the forty-first mirror 555 after passing through the second concave mirror 554. The light pulse is reflected by the forty-first mirror 555 to the third concave mirror 556. The light pulse is incident on the fourth concave mirror 558 after passing through the BBO crystal 557. The light pulse is reflected by the fourth concave mirror 558 to the forty-second mirror 551, and then is incident on the first concave mirror 552. The light pulse passes through the first concave mirror 552, the LBO crystal 553, the second concave mirror 554, the forty-first mirror 555, the third concave mirror 556, the BBO crystal 557, and the fourth concave mirror 558 again in the order described above after passing through the first concave mirror 552. The light pulse is transmitted to the fourteenth convex lens 559 after being reflected multiple times and then being transmitted through the fourth concave mirror 558.

[0015] Advantages:

[0016] 1. The application uses multiple hybrid filters to design a multi-wavelength pulse seed source, and realizes tunable multi-wavelength output.

[0017] 2. The application uses MZI-Sagnac hybrid to design a repetition frequency multiplication structure, and realizes high repetition frequency pulse output.

[0018] 3. The application uses optical lenses, optical modulators and the like to modulate spatial light, and realizes high-power narrow pulse output.

[0019] 4. The application uses a combination of barium metaborate and lithium triborate nonlinear crystals, and uses optical lenses to design multi-stage and multi-channel pulse compression, and ensures stable multi-wavelength ultrashort pulse output through pulse compression. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the overall structure block diagram of the application.

[0021] Figure 2 is the seed pulse source optical path diagram used by the application.

[0022] Figure 3 is the repetition frequency multiplication module optical path diagram used by the application.

[0023] Figure 4 is the shaping optical path module optical path diagram used by the application.

[0024] Figure 5 is the power amplification module optical path diagram used by the application.

[0025] Figure 6 is the pulse compression module optical path diagram used by the application.

[0026] Figure 7 is the optical spectrum diagram of the seed pulse source 1 output by the application.

[0027] Figure 8 is the frequency spectrum diagram of the seed pulse source 1 output by the application.

[0028] Figure 9 is the frequency spectrum diagram of the repetition frequency multiplication module 2 output by the application.

[0029] Figure 10 is the autocorrelation diagram of the pulse compression module 5 output by the application. DETAILED DESCRIPTION

[0030] The working principle of the application will be further described below in combination with the drawings, and it should be understood that the component parameters marked in the embodiments are preferred parameters used in the embodiments, and are not a limitation on the scope of protection.

[0031] The overall structure of the present application

[0032] As shown in Figure 1 , the overall structure block diagram of the present application is as shown in Figure 1 : the output end of the seed pulse source 1 is connected with the input end of the repetition frequency multiplication module 2, the output end of the repetition frequency multiplication module 2 is connected with the input end of the shaping optical path module 3, the output end of the shaping optical path module 3 is connected with the input end of the power amplification module 4, and the output end of the power amplification module 4 is connected with the input end of the pulse compression module 5. The seed pulse source 1 adopts a shared laser resonant cavity structure, internally parallelly integrates a Sagnac ring and a Lyot type filtering branch, utilizes a high birefringence fiber and a polarization controller to jointly regulate and control the transmission wavelength, realizes flexible tuning of multi-wavelength output, combines a nonlinear mode-locking mechanism and a multimode saturable absorber, realizes self-starting mode-locking through nonlinear phase shift accumulation, and effectively suppresses mode competition between multiple wavelengths; provides the repetition frequency multiplication module 2 with an ultrashort pulse seed source with independently tunable wavelength and high stability; the repetition frequency multiplication module 2 adopts a hybrid structure combining a Sagnac ring and an asymmetric MZI, the Sagnac ring pre-processes each input pulse into a pulse pair with fixed time delay based on the polarization interference principle, the pulse pair is injected into the asymmetric MZI, the optical path difference of two arms is accurately controlled, and the interference constructive and destructive effects are utilized to realize time domain interleaving and synthesis of multiple pulses, thereby efficiently improving the repetition frequency.

[0033] Embodiment 2 Seed pulse source

[0034] The optical path diagram of the seed pulse source 1 is as shown in Figure 2As shown, the structure is: the first pump source 101 is connected with the 980nm end of the first wavelength division multiplexer 102, the common end of the first wavelength division multiplexer 102 is connected with the input end of the first coupler 105 through the first erbium-doped fiber 103 and the first polarization-independent optical isolator 104, the 50% output end of the first coupler 105 is connected with the first polarizer 106, the optical pulse is connected with the 50% input end of the second coupler 111 after passing through the first polarizer 106, the first polarization controller 107, the first polarization-maintaining fiber 108, the second polarization controller 109 and the second polarizer 110; the other 50% output end of the first coupler 105 is connected with the 50% input end of the third coupler 112, the 50% output end of the third coupler 112 is connected with the third polarization controller 113, the third polarization controller 113 is connected with the first high-birefringence fiber 114, the first high-birefringence fiber 114 is connected with the fourth polarization controller 115, the fourth polarization controller 115 is connected with the second high-birefringence fiber 116, the second high-birefringence fiber 116 is connected with the other 50% input end of the third coupler 112, the other 50% output end of the third coupler 112 is connected with the first fiber delay line 117, the first fiber delay line 117 is connected with the other 50% input end of the second coupler 111, the optical pulse is output from the 20% output end of the fourth coupler 120. The seed pulse source 1 is provided with independent filtering branches arranged in parallel in a shared laser resonant cavity, which are a Sagnac ring filter and a Lyot filter, the transmission wavelength of which is determined by the fiber length and the birefringence, and the output wavelength can be adjusted by adjusting the polarization controller. The seed pulse source 1 is mode-locked by a multimode saturable absorber, and the nonlinear effect acts on all wavelength components. At the same time, the structure of the seed pulse source 1 is helpful to suppress the mode competition between different wavelengths, and the shared cavity structure ensures the inherent time-domain synchronization and coherence of different wavelength pulses; in addition, the wavelength can be independently and flexibly adjusted by adjusting the filtering branch, thereby providing a high-quality, high-stability multi-wavelength ultrashort pulse seed source for the whole system. The spectral diagram of the output of the embodiment is shown in Figure 7 As shown, the center wavelengths of the spectrum are 1549.08nm and 1567.52nm, and the 3dB bandwidths are 4.55nm and 4.28nm respectively. The frequency spectrum diagram of the output of the embodiment is shown in Figure 8 At this time, the repetition frequency is 23.4MHz, and the output power is about 150mW.

[0035] Embodiment 3, repetition frequency multiplication module

[0036] The optical path structure of the repetition frequency multiplication module 2 is shown in Figure 3 The light pulse passes through the second polarization-independent optical isolator 201, the sixth polarization controller 202, the input end of the fifth coupler 203, the 50% output end of the fifth coupler 203, the first single-mode optical fiber 204, the seventh polarization controller 205, the input end of the sixth coupler 206, the output end of the sixth coupler 206, the second optical fiber delay line 209, the eighth polarization controller 208, the third high-birefringence optical fiber 207, the other input end of the sixth coupler 206, the other output end of the sixth coupler 206, the input end of the seventh coupler 210, and the output end of the seventh coupler 210. The other output end of the fifth coupler 203 is connected with the second single-mode optical fiber 211, the third optical fiber delay line 212, the ninth polarization controller 213, and the other input end of the seventh coupler 210. The last light pulse is output from the output end of the seventh coupler 210. Each single input pulse is preprocessed into a pulse pair with a fixed interval in the time domain through a Sagnac loop with a built-in high-birefringence optical fiber. Then, the pulse pair is injected into an asymmetric MZI. By precisely controlling the optical path difference of the two arms, the sub-pulses from different original pulses are rearranged and interleaved in the time domain, thereby synthesizing a new pulse sequence with a multiplied repetition frequency. Through the collaborative design of the hybrid architecture, the module realizes a higher single-stage multiplication factor in fewer stages, significantly reducing the total insertion loss and timing jitter. The frequency spectrum diagram of the output of the embodiment is shown in Figure 9 At this time, the repetition frequency is 70.5 MHz, which is multiplied compared with the repetition frequency of the output of the embodiment 2.

[0037] Embodiment 4: Shaping optical path module

[0038] The optical path structure of the shaping optical path module 3 is shown in Figure 4As shown: the light pulse is transmitted to the first half-wave plate 301, reflected by the first mirror 302 and the second mirror 303 and enters the first expansion mirror 304, the light pulse is reflected by the third mirror 305 to the first spatial light modulator 306 after passing through the first expansion mirror 304, the light beam modulated by the first spatial light modulator 306 passes through the first convex lens 307, the second convex lens 308 and the non-polarization beam splitter 309, wherein one beam of light passing through the non-polarization beam splitter 309 is focused by the third convex lens 310 and then incident to the first feedback device 311, and the other beam of light passing through the non-polarization beam splitter 309 is focused by the fourth convex lens 312 and then output after passing through the fourth mirror 313. The wavefront of the light beam is precisely controlled by the spatial light modulator, the amplitude, phase and polarization state of the light pulse are actively controlled, and the adaptability of the system to complex applications is improved. The combination of the expansion mirror and the convex lens effectively suppresses the diffraction effect and ensures the uniformity and collimation of the light beam. Part of the light beam is monitored and closed-loop controlled by the feedback device, the output stability is improved, the effective conversion from the optical fiber to the spatial light path is realized, the light beam expansion, collimation and splitting are realized, and the light beam quality is optimized.

[0039] Embodiment 5 power amplification module

[0040] The optical path structure of the power amplification module 4 is as shown in Figure 5The light pulse is transmitted to the passive optical fiber 402 through the semiconductor saturable absorber mirror 401 (SESAM), the second erbium-doped optical fiber 403, and the input end of the first fiber Bragg grating 404, the output end of the first fiber Bragg grating 404 is connected to the common end of the second wavelength division multiplexer 405, the 980nm end of the second wavelength division multiplexer 405 is connected to the second pump source 406, the other common end of the second wavelength division multiplexer 405 is connected to the input end of the third isolator 407, the light output from the output end of the third isolator 407 passes through the fifth mirror 408, the sixth mirror 409, the fifth convex lens 410, the sixth convex lens 411, the input mirror 412, the first Er: YAP crystal 413, the eighth coupler 414, the first band-pass filter 415, the third polarizer 416, the seventh convex lens 417, the dichroic mirror 418, the third pump source 419 is connected to the 980nm end of the third wavelength division multiplexer 420, the light pulse passes through the eighth convex lens 421, the ninth convex lens 422, and the dichroic mirror 418 from the common end of the third wavelength division multiplexer 420, and the light pulse is output after passing through the second Er: YAP crystal 423 and the second band-pass filter 424. The power amplification module 4 combines the advantages of optical fiber and solid-state amplifier, and takes into account high gain and high energy output. In the amplification process, the gain competition between wavelengths is effectively suppressed, and the degradation of multi-wavelength output is avoided. Through multiple isolators, filters and polarization control, the amplification process is stable, the output power is high and the fluctuation is small. Multiple pump sources and wavelength division multiplexers are used to improve energy conversion efficiency, and the output power at this time is about 1W.

[0041] Example 6 Pulse compression module

[0042] The optical path structure of the pulse compression module 5 is as shown in Figure 6As shown: the light pulse is incident to the second polarizing beam splitter 502 through the first polarizing beam splitter 501, part of the light pulse passing through the second polarizing beam splitter 502 is transmitted to the seventh mirror 503, the light pulse is reflected by the seventh mirror 503 and then passes through the eighth mirror 504, the ninth mirror 505 and the tenth mirror 506 in turn, the light pulse reflected by the tenth mirror 506 is incident to the first grating 512, the first grating 512 reflects the light pulse to the second grating 513, the second grating 513 reflects the light pulse to the eleventh mirror 514, the light pulse reaches the eleventh mirror 514 and is reflected back to the first grating 512 along the input route, the first grating 512 transmits the light pulse to the twelfth mirror 515, the light pulse is reflected by the twelfth mirror 515 to the thirteenth mirror 517, and then is incident to the tenth convex lens 535 through the thirteenth mirror 517, another part of the light pulse output from the second polarizing beam splitter 502 is transmitted to the fourteenth mirror 507, the light pulse is reflected by the fourteenth mirror 507 and then passes through the fifteenth mirror 508, the sixteenth mirror 509, the seventeenth mirror 510 and the eighteenth mirror 511 in turn, the light pulse reflected by the eighteenth mirror 511 enters the first grating 512 in parallel with the light pulse reflected by the tenth mirror 506, the light pulse incident to the first grating 512 from the tenth mirror 506 passes through the first grating 512, the second grating 513, the eleventh mirror 514 and returns to the first grating 512 along the input route as described above, the light pulse is transmitted by the first grating 512 to the twelfth mirror 515, the light pulse is reflected by the twelfth mirror 515 to the nineteenth mirror 516, and then is incident to the tenth convex lens 535 through the nineteenth mirror 516, the light pulse is transmitted by another output end of the first polarizing beam splitter 501 to the twentieth mirror 518, and then is transmitted to the third polarizing beam splitter 519 through the twentieth mirror 518, part of the light pulse passing through the third polarizing beam splitter 519 is transmitted to the twenty-first mirror 520, the light pulse is reflected by the twenty-first mirror 520 and then passes through the twenty-second mirror 521, the twenty-third mirror 522 and the twenty-fourth mirror 523 in turn, the light pulse reflected by the twenty-fourth mirror 523 is incident to the third grating 529, the third grating 529 reflects the light pulse to the fourth grating 530, the fourth grating 530 reflects the light pulse to the twenty-fifth mirror 531, the light pulse reaches the twenty-fifth mirror 531 and is reflected back to the third grating 529 along the input route, the third grating 529 transmits the light pulse to the twenty-sixth mirror 532, the light pulse is reflected by the twenty-sixth mirror 532 to the twenty-seventh mirror 534, and then is reflected to the tenth convex lens 535 through the twenty-seventh mirror 534, another part of the light pulse output from the third polarizing beam splitter 519 is transmitted to the twenty-eighth mirror 524,The light pulse is reflected by the twenty-eighth mirror 524, and then passes through the twenty-ninth mirror 525, the thirtieth mirror 526, the thirty-first mirror 527 and the thirty-second mirror 528. The light pulse reflected by the thirty-second mirror 528 enters the third grating 529 in parallel with the light pulse reflected by the twenty-fourth mirror 523. The light pulse entering the third grating 529 from the twenty-fourth mirror 523 passes through the third grating 529, the fourth grating 530 and the twenty-fifth mirror 531 in turn, and returns to the third grating 529 along the input route. The light pulse is transmitted by the third grating 529 to the twenty-sixth mirror 532. The light pulse is reflected by the twenty-sixth mirror 532 to the thirty-third mirror 533, and then reflected by the thirty-third mirror 533 to the tenth convex lens 535. The four light pulses passing through the nineteenth mirror 516, the thirteenth mirror 517, the twenty-seventh mirror 534 and the thirty-third mirror 533 in parallel enter the tenth convex lens 535. The light pulses are focused by the tenth convex lens 535 and then fused. The fused light pulse is reflected by the thirty-fourth mirror 536 to the thirty-fifth mirror 537. The light pulse is transmitted by the thirty-fifth mirror 537 to the second half-wave plate 538. The light pulse is reflected by the thirty-sixth mirror 539 to the second spatial light modulator 540 through the second half-wave plate 538. The light beam modulated by the second spatial light modulator 540 is focused by the eleventh convex lens 541, the twelfth convex lens 542 and the thirteenth convex lens 543, and then enters the second feedback device 544. The light pulse is transmitted by the second feedback device 544 to the thirty-seventh mirror 545, the thirty-eighth mirror 546 and the third half-wave plate 547. The light pulse is incident on the fourth polarization beam splitter 548 through the third half-wave plate 547. The light pulse output by the fourth polarization beam splitter 548 in parallel along the incident direction is transmitted to the thirty-ninth mirror 549. The light pulse is reflected by the thirty-ninth mirror 549 to the fortyth mirror 550. The light pulse is reflected by the fortyth mirror 550 to the first concave mirror 552. The light pulse is incident on the second concave mirror 554 through the LBO crystal 553. The light pulse is incident on the forty-first mirror 555 through the second concave mirror 554. The light pulse is reflected by the forty-first mirror 555 to the third concave mirror 556. The light pulse output by the third concave mirror 556 is incident on the fourth concave mirror 558 through the BBO crystal 557. The light pulse is reflected by the fourth concave mirror 558 to the forty-second mirror 551, and then is incident on the first concave mirror 552. The light pulse passes through the first concave mirror 552, the LBO crystal 553, the second concave mirror 554, the forty-first mirror 555, the third concave mirror 556, the BBO crystal 557 and the fourth concave mirror 558 again along the route described above. After multiple reflections, the light pulse returns to the fourth concave mirror 558. The light pulse is transmitted to the fourteenth convex lens 559 by being transmitted and output by the fourth concave mirror 558,The light pulse output. The pulse compression module 5 combines a grating pair and a nonlinear crystal to achieve strong dispersion compensation and pulse width compression. Frequency conversion is achieved through LBO and BBO crystals to support wavelength tuning and expansion. Through feedback control and multi-mirror path design, the output pulse timing is ensured to be consistent, the compression efficiency and stability are significantly improved, and the output multi-wavelength pulse is more stable. The autocorrelation diagram of the output of the embodiment is shown in FIG. 8, and the pulse width at this time is 0.26 ps. Figure 10

[0043] Embodiment 7 Working principle of the present application

[0044] The working principle of the present application is described in combination with the above embodiments and the accompanying drawings.

[0045] ​The seed pulse source 1 is provided with independent filter branches in a shared laser resonant cavity, which are respectively a Sagnac ring filter and a Lyot filter. The transmission wavelength of the filter branches is determined by the fiber length and the birefringence. The output wavelength can be adjusted by adjusting the polarization controller. The seed pulse source 1 is mode-locked by a multimode saturable absorber, and the nonlinear effect acts on all wavelength components. At the same time, the structure of the seed pulse source 1 helps to suppress the mode competition between different wavelengths, and the shared cavity structure ensures the inherent time-domain synchronization and coherence of the pulses of different wavelengths. In addition, the wavelength can be independently and flexibly adjusted by adjusting the filter branches, thereby providing a high-quality, high-stability multi-wavelength ultra-short pulse seed source for the entire system. The repetition frequency multiplication module 2 pre-processes each single pulse into a pulse pair with a fixed interval in the time domain through a Sagnac ring with a built-in high-birefringence fiber. Then, the pulse pair is injected into an asymmetric MZI, and the optical path difference of the two arms is accurately controlled to rearrange and interleave the sub-pulses from different original pulses in the time domain, thereby synthesizing a new pulse sequence with multiplied repetition frequency. Through the collaborative design of the hybrid architecture, the module realizes a higher single-stage multiplication factor in fewer stages, thereby significantly reducing the total insertion loss and timing jitter. The shaping optical path module 3 accurately controls the wavefront of the light beam through a spatial light modulator, thereby actively controlling the amplitude, phase and polarization state of the optical pulse and improving the adaptability of the system to complex applications. The combination of an expander and a convex lens effectively suppresses the diffraction effect and ensures the uniformity and collimation of the light beam. Part of the light beam is monitored and controlled in real time through a feedback device, thereby improving the output stability, realizing the effective conversion from fiber output to spatial optical path, realizing beam expansion, collimation and beam splitting, and optimizing the beam quality. The power amplification module 4 combines the advantages of fiber and solid-state amplifiers, and takes into account high gain and high energy output. The gain competition between wavelengths is effectively suppressed during the amplification process, thereby avoiding the degradation of multi-wavelength output. Through multiple isolators, filters and polarization controllers, the amplification process is stable, the output power is high, and the fluctuation is small. The use of multiple pump sources and wavelength division multiplexers improves the energy conversion efficiency. The pulse compression module 5 combines a grating pair and a nonlinear crystal to realize strong dispersion compensation and pulse width compression. The LBO and BBO crystals realize frequency conversion, support wavelength tuning and expansion. Through feedback control and multi-mirror path design, the output pulse timing is ensured, the compression efficiency and stability are significantly improved, and the output multi-wavelength pulse is more stable.

Claims

1. A tunable high-repetition-rate high-power multi-wavelength optical pulse generation system, which is structured as follows: the output end of a seed pulse source (1) is connected with the input end of a repetition rate multiplication module (2), the output end of the repetition rate multiplication module (2) is connected with the input end of a shaping optical path module (3), the output end of the shaping optical path module (3) is connected with the input end of a power amplification module (4), and the output end of the power amplification module (4) is connected with the input end of a pulse compression module (5); characterized in that, The seed pulse source (1) adopts a shared laser resonant cavity structure, internally parallelly integrates a Sagnac loop and a Lyot type filtering branch, utilizes a high birefringence fiber and a polarization controller to jointly regulate and control a transmission wavelength, realizes flexible tuning of multi-wavelength output, combines a nonlinear mode-locking mechanism and a multimode saturable absorber, realizes self-starting mode-locking through nonlinear phase shift accumulation, and effectively suppresses mode competition among multiple wavelengths; the frequency multiplication module (2) is provided with a wavelength independently tunable, high stability ultrashort pulse seed source; the frequency multiplication module (2) adopts a hybrid structure combining a Sagnac loop and an asymmetric MZI, the Sagnac loop is based on a polarization interference principle, each input pulse is preprocessed into a pulse pair with a fixed time delay, the pulse pair is injected into the asymmetric MZI, the optical path difference of two arms is accurately controlled, and the interference constructive and destructive effects are utilized, so that the time domain interleaving and synthesis of multiple pulses are realized, and the repetition frequency is effectively improved; The structure of the seed pulse source (1) is as follows: the first pump source (101) is connected with the 980nm end of the first wavelength division multiplexer (102), the common end of the first wavelength division multiplexer (102) is connected with the input end of the first coupler (105) through the first erbium-doped fiber (103) and the first polarization-independent optical isolator (104), the 50% output end of the first coupler (105) is connected with the first polarizer (106), the optical pulse is connected with the 50% input end of the second coupler (111) after passing through the first polarizer (106), the first polarization controller (107), the first polarization maintaining fiber (108), the second polarization controller (109), and the second polarizer (110); the other 50% output end of the first coupler (105) is connected with the 50% input end of the third coupler (112), the 50% output end of the third coupler (112) is connected with the third polarization controller (113), the third polarization controller (113) is connected with the first high birefringence fiber (114), the first high birefringence fiber (114) is connected with the fourth polarization controller (115), the fourth polarization controller (115) is connected with the second high birefringence fiber (116), the second high birefringence fiber (116) is connected with the other 50% input end of the third coupler (112), the other 50% output end of the third coupler (112) is connected with the first fiber delay line (117), the first fiber delay line (117) is connected with the other 50% input end of the second coupler (111), the optical pulse is output from the output end of the second coupler (111) after passing through the fifth polarization controller (118), the extruded polarization controller (119) containing SMF-GIMF-SMF, the extruded polarization controller (119) is connected with the input end of the fourth coupler (120), the 80% output end of the fourth coupler (120) is connected with the other common end of the first wavelength division multiplexer (102), and the optical pulse is output from the 20% output end of the fourth coupler (120). The heavy frequency multiplication module (2) has the following optical path structure: the light pulse passes through a second polarization-independent optical isolator (201), a sixth polarization controller (202), the sixth polarization controller (202) is connected with the input end of a fifth coupler (203), 50% of the output end of the fifth coupler (203) is connected with a first single-mode optical fiber (204), the first single-mode optical fiber (204) is connected with a seventh polarization controller (205), the seventh polarization controller (205) is connected with the input end of a sixth coupler (206), the output end of the sixth coupler (206) is connected with a second optical fiber delay line (209), the second optical fiber delay line (209) is connected with an eighth polarization controller (208), the eighth polarization controller (208) is connected with a third high-birefringence optical fiber (207), the third high-birefringence optical fiber (207) is connected with the other input end of the sixth coupler (206), the other output end of the sixth coupler (206) is connected with the input end of a seventh coupler (210); the other output end of the fifth coupler (203) is connected with a second single-mode optical fiber (211), the second single-mode optical fiber (211) is connected with a third optical fiber delay line (212), the third optical fiber delay line (212) is connected with a ninth polarization controller (213), the ninth polarization controller (213) is connected with the other input end of the seventh coupler (210), and finally the light pulse is output from the output end of the seventh coupler (210).

2. The tunable high repetition rate, high power, multi-wavelength optical pulse generation system according to claim 1, characterized in that, The shaping optical path module (3) has the following optical path structure: the light pulse is transmitted to a first half-wave plate (301), reflected by a first mirror (302) and a second mirror (303) and then enters a first expansion mirror (304), the light pulse is reflected by a third mirror (305) to a first spatial light modulator (306) after passing through the first expansion mirror (304), and the light beam modulated by the first spatial light modulator (306) passes through a first convex lens (307), a second convex lens (308) and a non-polarization beam splitter (309), wherein one light beam passing through the non-polarization beam splitter (309) is focused by a third convex lens (310) and then incident on a first feedback device (311), and the other light beam passing through the non-polarization beam splitter (309) is focused by a fourth convex lens (312) and then output after passing through a fourth mirror (313).

3. The tunable high repetition rate, high power, multi-wavelength optical pulse generation system according to claim 1, characterized in that, The power amplification module (4) has the following optical path structure: optical pulses are transmitted to a passive optical fiber (402) through a semiconductor saturable absorber mirror (401), a second erbium-doped optical fiber (403) is connected with an input end of a first fiber Bragg grating (404), an output end of the first fiber Bragg grating (404) is connected with a common end of a second wavelength division multiplexer (405), a 980nm end of the second wavelength division multiplexer (405) is connected with a second pump source (406), another common end of the second wavelength division multiplexer (405) is connected with an input end of a third isolator (407), an output end of the third isolator (407) outputs light which passes through a fifth mirror (408), a sixth mirror (409), a fifth convex lens (410), a sixth convex lens (411), an input mirror (412), a first Er: YAP crystal (413), an eighth coupler (414), a first band-pass filter (415), a third polarizer (416), a seventh convex lens (417), a dichroic mirror (418), a third pump source (419) is connected with a 980nm end of a third wavelength division multiplexer (420), optical pulses from the common end of the third wavelength division multiplexer (420) pass through an eighth convex lens (421), a ninth convex lens (422) and the dichroic mirror (418), and after the optical pulses are transmitted out from the dichroic mirror (418), they pass through a second Er: YAP crystal (423) and a second band-pass filter (424) and are then output.

4. The system of claim 1, wherein, The pulse compression module (5) has the following optical path structure: the light pulse is incident to the second polarization beam splitter (502) through the first polarization beam splitter (501), part of the light pulse passing through the second polarization beam splitter (502) is transmitted to the seventh mirror (503), the light pulse is reflected by the seventh mirror (503) and then is reflected by the eighth mirror (504), the ninth mirror (505), and the tenth mirror (506) in sequence, the light pulse reflected by the tenth mirror (506) is incident to the first grating (512), the first grating (512) reflects the light pulse to the second grating (513), the second grating (513) reflects the light pulse to the eleventh mirror (514), the light pulse reaches the eleventh mirror (514) and is reflected back to the first grating (512) along the input route, the first grating (512) transmits the light pulse to the twelfth mirror (515), the light pulse is reflected by the twelfth mirror (515) to the thirteenth mirror (517), and then is incident to the tenth convex lens (535), another part of the light pulse output from the second polarization beam splitter (502) is transmitted to the fourteenth mirror (507), the light pulse is reflected by the fourteenth mirror (507) and then is reflected by the fifteenth mirror (508), the sixteenth mirror (509), the seventeenth mirror (510), and the eighteenth mirror (511) in sequence, the light pulse reflected by the eighteenth mirror (511) and the light pulse reflected by the tenth mirror (506) enter the first grating (512) in parallel, the light pulse incident to the first grating (512) from the tenth mirror (506) is transmitted to the first grating (512), the second grating (513), the eleventh mirror (514) in sequence and returns to the first grating (512) along the input route, the light pulse is transmitted by the first grating (512) to the twelfth mirror (515), the light pulse is reflected by the twelfth mirror (515) to the nineteenth mirror (516), and then is incident to the tenth convex lens (535), the light pulse is transmitted by another output end of the first polarization beam splitter (501) to the twentieth mirror (518), is transmitted to the third polarization beam splitter (519) through the twentieth mirror (518), part of the light pulse passing through the third polarization beam splitter (519) is transmitted to the twenty-first mirror (520), the light pulse is reflected by the twenty-first mirror (520) and then is reflected by the twenty-second mirror (521), the twenty-third mirror (522), and the twenty-fourth mirror (523) in sequence, the light pulse reflected by the twenty-fourth mirror (523) is incident to the third grating (529), the third grating (529) reflects the light pulse to the fourth grating (530), the fourth grating (530) reflects the light pulse to the twenty-fifth mirror (531), the light pulse reaches the twenty-fifth mirror (531) and is reflected back to the third grating (529) along the input route,The third grating (529) transmits the light pulses to the twenty-sixth mirror (532), the light pulses are reflected by the twenty-sixth mirror (532) to the twenty-seventh mirror (534), and are reflected by the twenty-seventh mirror (534) to the tenth convex lens (535). Another part of the light pulses output from the third polarization beam splitter (519) is transmitted to the twenty-eighth mirror (524), and the light pulses are reflected by the twenty-eighth mirror (524) and then pass through the twenty-ninth mirror (525), the thirtieth mirror (526), the thirty-first mirror (527), and the thirty-second mirror (528) in sequence. The light pulses reflected by the thirty-second mirror (528) enter the third grating (529) in parallel with the light pulses reflected by the twenty-fourth mirror (523). The light pulses enter the third grating (529) from the twenty-fourth mirror (523) along the incident path as described above, pass through the third grating (529), the fourth grating (530), and the twenty-fifth mirror (531) in sequence, and return to the third grating (529) along the input path. The light pulses are transmitted by the third grating (529) to the twenty-sixth mirror (532), reflected by the twenty-sixth mirror (532) to the thirty-third mirror (533), reflected by the thirty-third mirror (533) to the tenth convex lens (535), and enter the tenth convex lens (535) in parallel after passing through the nineteenth mirror (516), the thirteenth mirror (517), the twenty-seventh mirror (534), and the thirty-third mirror (533) respectively. The light pulses are focused by the tenth convex lens (535) and then fused. The fused light pulses are reflected by the thirty-fourth mirror (536) to the thirty-fifth mirror (537), transmitted by the thirty-fifth mirror (537) to the second half-wave plate (538), reflected by the thirty-sixth mirror (539) to the second spatial light modulator (540) after passing through the second half-wave plate (538), and then pass through the eleventh convex lens (541), the twelfth convex lens (542), and the thirteenth convex lens (543) to be focused and incident on the second feedback device (544). The light pulses are transmitted by the second feedback device (544) to the thirty-seventh mirror (545), the thirty-eighth mirror (546), and the third half-wave plate (547), incident on the fourth polarization beam splitter (548) after passing through the third half-wave plate (547), output from the output end parallel to the incident direction of the fourth polarization beam splitter (548), transmitted to the thirty-ninth mirror (549), reflected by the thirty-ninth mirror (549) to the fortieth mirror (550), reflected by the fortieth mirror (550) to the first concave mirror (552), incident on the second concave mirror (554) through the LBO crystal (553) after passing through the first concave mirror (552), incident on the forty-first mirror (555) after passing through the second concave mirror (554),After being reflected by the forty-first mirror (555) to the third concave mirror (556), the light pulse output by the third concave mirror (556) passes through the BBO crystal (557) and is incident to the fourth concave mirror (558), and the light pulse is reflected by the fourth concave mirror (558) to the forty-second mirror (551), and then is incident to the first concave mirror (552). After the light pulse passes through the first concave mirror (552) again according to the above route, it passes through the first concave mirror (552), the LBO crystal (553), the second concave mirror (554), the forty-first mirror (555), the third concave mirror (556), the BBO crystal (557), and the fourth concave mirror (558) multiple times. After multiple reflections, the light pulse returns to the fourth concave mirror (558), and the light pulse is transmitted and output by the fourth concave mirror (558) to the fourteenth convex lens (559), and the light pulse is output.

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