An ultrashort pulse source for a dense wavelength division multiplexing system

Abstract

An ultrashort pulse source for a dense wavelength division multiplexing system of the present invention belongs to the technical field of optoelectronic devices, and its structure is as follows: the output end of a seed pulse source (1) is connected to the input end of a pulse width broadening module (2), the output end of the pulse width broadening module (2) is connected to the input end of a pulse picking module (3), the output end of the pulse picking module (3) is connected to the input end of a pulse time domain segmentation module (4), the output end of the pulse time domain segmentation module (4) is connected to the input end of a first-stage pulse width compression module (5), the output end of the first-stage pulse width compression module (5) is connected to the input end of a polarization pulse coherent superposition module (6), and the output end of the polarization pulse coherent superposition module (6) is connected to the input end of a second-stage pulse width compression module (7). The present invention has the advantages of high output pulse energy, high power, ultrashort pulse width, multi-wavelength output, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices, and particularly relates to an ultrashort pulse source for a dense wavelength division multiplexing system. Background Art

[0002] The requirements for network bandwidth and reliability of various new services are getting higher and higher. The characteristics of the dense wavelength division multiplexing system, such as ultra-large capacity, ultra-long distance transmission, and stable performance, make its importance more prominent in the development of the Internet. It will still be an important basic support platform for the future development of the Internet. In addition, the dense wavelength division multiplexing technology can greatly improve the capacity of the optical fiber communication system and is the most economical and effective way to realize the upgrade and expansion of the optical fiber system, becoming an inevitable trend in the development of communication.

[0003] In a dense wavelength division multiplexing system, the traditional light source solution is to use an array of lasers, and the number of channels is met by increasing the number of individual lasers, which undoubtedly increases the cost and complexity of the system. It is difficult to control the longitudinal mode of a Fabry-Perot laser. Usually, the length of the laser is on the order of hundreds of micrometers, and the corresponding mode spacing is on the order of 1 nm, while the gain spectral width of the laser reaches dozens of nm, and the possibility of multi-longitudinal mode lasing is quite large. A distributed feedback semiconductor laser with a common structure is prone to multimode operation under high-speed modulation, thus limiting the transmission rate. A distributed Bragg reflector semiconductor laser is tuned by changing the injection current in the grating region, which results in a large spectral broadening. In addition, a distributed Bragg reflector semiconductor laser needs to adjust the currents of at least two electrodes to fix the lasing wavelength, which is not conducive to practical applications.

[0004] The light source of a dense wavelength division multiplexing system is the main equipment for backbone network communication and usually needs to work continuously for several years. How to ensure the long-term stable operation of the light source of the dense wavelength division multiplexing system is one of the key technologies in light source design; at the same time, in a dense wavelength division multiplexing system, many channels are allocated, and the wavelength difference between adjacent channels is very small, 0.8 nm or even smaller. This requires the signal source to have characteristics such as frequency stability, narrow linewidth, good frequency selectivity, and a wide wavelength tuning range.

[0005] In summary, the currently existing ultrashort pulse sources capable of generating signals for a dense wavelength division multiplexing system all have inherent drawbacks and need to be further improved. Summary of the Invention

[0006] In order to overcome the characteristics of traditional systems such as insufficient pulse power, narrow wavelength tuning range, and unstable frequency, the present invention provides an ultrashort pulse source for a dense wavelength division multiplexing system. A multi-wavelength tunable ultrashort pulse is obtained through a seed pulse source module, the power amplification and pulse width compression of the pulse are achieved through a first-stage pulse width compression module, and the pulse width is further compressed through a second-stage pulse width compression module, thereby obtaining a mid-infrared high-power ultrashort pulse for the dense wavelength division multiplexing system.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] An ultrashort pulse source for a dense wavelength division multiplexing system has the following structure: the output end of the seed pulse source 1 is connected to the input end of the pulse width broadening module 2, the output end of the pulse width broadening module 2 is connected to the input end of the pulse pick-up module 3, the output end of the pulse pick-up module 3 is connected to the input end of the pulse time-domain division module 4, the output end of the pulse time-domain division module 4 is connected to the input end of the first-stage pulse width compression module 5, the output end of the first-stage pulse width compression module 5 is connected to the input end of the polarization pulse coherent superposition module 6, and the output end of the polarization pulse coherent superposition module 6 is connected to the input end of the second-stage pulse width compression module 7;

[0009] The structure of the seed pulse source module 1 is as follows: the pump source 101 is connected to the 980 nm end of the wavelength division multiplexer 102, the 1550 nm end of the wavelength division multiplexer 102 is connected to the input end of the first isolator 103, the output end of the first isolator 103 is connected to the input end of the erbium-doped fiber 104 through the erbium-doped fiber 104, the output end of the second isolator 105 is connected to the input end of the filter 106, the output end of the filter 106 is connected to the input end of the first polarization controller 107, the output end of the first polarization controller 107 is connected to the input end of the first collimator 109 through the single-mode fiber 108, and the optical pulse passes through the first collimator 109, the first half-wave plate 110, the first quarter-wave plate 111, the first polarization-sensitive isolator 112, the first polarization beam splitter 113, and the second quarter-wave plate 114 and then is transmitted to the second collimator 115. The second collimator 115 is connected to the input end of the second coupler 117 through the phase-shifted long-period grating 116. The direct output end of the second coupler 117 is connected to the common end of the wavelength division multiplexer 102, and the coupled output end of the second coupler 117 is connected to the input end of the second polarization controller 120. The output end of the second polarization controller 120 is connected to the output end 118 of the third polarization controller through the polarization-maintaining fiber 119. The input end of the third polarization controller 118 is connected to the other input end of the second coupler 117, where the output end of the first polarization beam splitter 113 in the vertical incident direction is used as the output of the seed pulse source module;

[0010] The pulse width broadening module 2 has the following optical path structure. The optical pulse is transmitted to the first grating 202 through the first mirror 201. After the first grating 202 transmits the optical pulse to the second mirror 203, it is reflected to the third mirror 204. The third mirror 204 reflects the optical pulse back to the first grating 202. The pulse output by the first grating 202 is transmitted to the fourth mirror 206 through the first convex lens 205 and then reflected back to the first grating 202 by the first convex lens 205. The optical pulse is transmitted to the second mirror 203 through the first grating 202. The second mirror 203 reflects the optical pulse and after being reflected by the third mirror 204, it is incident on the first grating 202. The optical pulse output by the first grating 202 is incident on the Porro prism 207 and is reflected back to the first grating 202 by the Porro prism 207. The optical pulse is transmitted to the second mirror 203 after passing through the first grating 202, and then reflected to the third mirror 204. The third mirror 204 reflects the optical pulse back to the first grating 202. After being output by the first grating 202, it is transmitted to the fourth mirror 206 through the first convex lens 205, and after being reflected by the fourth mirror 206, it is transmitted to the first grating 202 through the first convex lens 205 again. It is transmitted to the second mirror 203 through the first grating 202, and then reflected to the third mirror 204. The third mirror 204 reflects the optical pulse back to the first grating 202, is transmitted to the Porro prism 207 through the first grating 202 and is reflected back to the first grating 202 by the Porro prism 207, and finally is output by the first grating 202;

[0011] The pulse pickup module 3 has the following optical path structure. The optical pulse is incident on the second convex lens 301. The optical pulse passes through the second convex lens 301, the acousto-optic modulator 302, the third convex lens 303, the third isolator 304, and the second half-wave plate 305 and then is incident on the fifth mirror 306. The optical pulse is reflected by the fifth mirror 306 to the sixth mirror 307 and then is incident on the fourth convex lens 308. The optical pulse passes through the fourth convex lens 308, the third collimator 309, the second erbium-doped fiber 310, the fourth collimator 311, and the fifth convex lens 312 and then is incident on the seventh mirror 313. The pump light generated by the first photodiode 316 passes through the fifth collimator 315 and the sixth convex lens 314 and then is fused with the optical pulse incident on the seventh mirror 313 via the fourth collimator 311 and the fifth convex lens 312. The fused optical pulse is reflected by the seventh mirror 313 to the eighth mirror 317. The eighth mirror 317 reflects the optical pulse to the third half-wave plate 318. The optical pulse passes through the third half-wave plate 318, the third quarter-wave plate 319, the band-pass filter 320, and the fourth half-wave plate 321 and then is incident on the second grating 325. The optical pulse is transmitted by the second grating 325 to the third grating 326. The third grating 326 transmits the optical pulse to the ninth mirror 327. The ninth mirror 327 reflects the pulse back to the third grating 326. The optical pulse is transmitted by the third grating 326 to the second grating 325. The optical pulse output by the second grating 325 is transmitted to the tenth mirror 322 and is reflected by the tenth mirror 322 into the fifth half-wave plate 323 and finally is output through the second polarization beam splitter 324;

[0012] The partial pulse time-domain splitting module 4 has the following optical path structure. The optical pulse is incident on the input end of the third polarization beam splitter 402 through the sixth half-wave plate 401. The optical pulse is output from the output end of the third polarization beam splitter 402 in the direction perpendicular to the incident direction and is transmitted to the eleventh mirror 404 through the fourth quarter-wave plate 403. The eleventh mirror 404 reflects the optical pulse back to the fourth quarter-wave plate 403, and the fourth quarter-wave plate 403 transmits the optical pulse to the third polarization beam splitter 402 again. At the same time, the optical pulse is output from another output end of the third polarization beam splitter 402 in the direction perpendicular to the incident direction, is transmitted to the twelfth mirror 406 and the first piezoelectric actuator 407 through the fifth quarter-wave plate 405. Then, the optical pulse is reflected back to the fifth quarter-wave plate 405 by the twelfth mirror 406, and the fifth quarter-wave plate 405 transmits the optical pulse back to the third polarization beam splitter 402 again. The optical pulse is output from the port of the third polarization beam splitter 402 parallel to the incident direction, is transmitted to the fourth polarization beam splitter 409 through the seventh half-wave plate 408. The optical pulse passes through the sixth quarter-wave plate 410 from the port of the fourth polarization beam splitter 409 perpendicular to the incident direction and is transmitted to the thirteenth mirror 411. The thirteenth mirror 411 reflects the optical pulse back to the sixth quarter-wave plate 410, and the sixth quarter-wave plate 410 transmits the optical pulse back to the fourth polarization beam splitter 409 again. At the same time, the optical pulse passes through the seventh quarter-wave plate 412 from another port of the fourth polarization beam splitter 409 perpendicular to the incident direction, is transmitted to the fourteenth mirror 413 and the second piezoelectric actuator 414. Then, the optical pulse is reflected back to the seventh quarter-wave plate 412 by the fourteenth mirror 413, and the seventh quarter-wave plate 412 transmits the optical pulse to the fourth polarization beam splitter 409 again. The optical pulse is output from the output end of the fourth polarization beam splitter 409 parallel to the incident direction;

[0013] The first-stage pulse width compression module 5 has the following optical path structure. The optical pulse is transmitted to the fourth grating 5001, and after being reflected by the fourth grating 5001, it reaches the concave mirror 5002. The concave mirror 5002 reflects the optical pulse to the fifteenth mirror 5003. After the optical pulse is reflected by the fifteenth mirror 5003 and then reaches the concave mirror 5002, it is transmitted by the concave mirror 5002 to the fourth grating 5001. After passing through the fourth grating 5001, the optical pulse is transmitted through the concave mirror 5002 and the fifteenth mirror 5003 again along the route described above. After multiple reflections, the optical pulse returns to the fourth grating 5001. The fourth grating 5001 reflects the optical pulse to the sixteenth mirror 5004. The optical pulse is transmitted by the sixteenth mirror 5004 to the seventeenth mirror 5005, transmitted by the seventeenth mirror 5005 to the eighteenth mirror 5006, and transmitted by the eighteenth mirror 5006 to the nineteenth mirror 5007. Then, the optical pulse undergoes spectral shaping through seven mirrors in sequence: The optical pulse passes through the twentieth mirror 5008, the twenty-first mirror 5009, the twenty-second mirror 5010, the twenty-third mirror 5011, the twenty-fourth mirror 5012, the twenty-fifth mirror 5013, and the twenty-sixth mirror 5014 in sequence. After being reflected, the optical pulse is incident on the twenty-seventh mirror 5015. The optical pulse is incident on the input end of the first beam splitter 5016 through the twenty-seventh mirror 5015, and is transmitted from the output end of the first beam splitter 5016 to the twenty-eighth mirror 5017. After being reflected by the twenty-eighth mirror 5017, the optical pulse is reflected by the twenty-ninth mirror 5018, and then reflected by the twenty-ninth mirror 5018 to the thirtieth mirror 5019. The thirtieth mirror 5019 reflects the optical pulse to the thirty-first mirror 5020. The optical pulse is reflected by the thirty-first mirror 5020 to the seventh convex lens 5021. After passing through the seventh convex lens 5021, the eighth convex lens 5022, and the first dichroic mirror 5023, the optical pulse is transmitted through the first dichroic mirror 5023. The optical pulse is fused with the optical pulse that is reflected by the sixty-third mirror 5107 and then reflected and output after reaching the first dichroic mirror 5023. The fused optical pulse is transmitted through the first dichroic mirror 5023 to the first KTiAsO4 crystal 5024. The optical pulse is transmitted through the first KTiAsO4 crystal 5024 to the second dichroic mirror 5025. The short-wavelength optical pulse reflected from the second dichroic mirror 5025 is transmitted to the thirty-second mirror 5103. The long-wavelength optical pulse transmitted through the second dichroic mirror 5025 is transmitted to the third dichroic mirror 5026. The optical pulse reflected by the third dichroic mirror 5026 is transmitted to the thirty-third mirror 5104. The optical pulse transmitted through the third dichroic mirror 5026 is incident on the thirty-fourth mirror 5027. The optical pulse is reflected by the thirty-fourth mirror 5027 to the thirty-fifth mirror 5028, reflected by the thirty-fifth mirror 5028 to the ninth convex lens 5029, transmitted by the ninth convex lens 5029 to the tenth convex lens 5030, and after passing through the tenth convex lens 5030, is incident on the thirty-sixth mirror 5031.The optical pulse is reflected by the thirty-sixth mirror 5031 to the thirty-seventh mirror 5032, reflected by the thirty-seventh mirror 5032 to the thirty-eighth mirror 5033, reflected by the thirty-eighth mirror 5033 to the thirty-ninth mirror 5034, transmitted by the thirty-ninth mirror 5034 to the fourth dichroic mirror 5035, transmitted by the fourth dichroic mirror 5035 to the second KTiAsO4 crystal 5036, the optical pulse is transmitted by the second KTiAsO4 crystal 5036 to the fifth dichroic mirror 5037, the optical pulse reflected from the fifth dichroic mirror 5037 is transmitted to the fortieth mirror 5105, the optical pulse transmitted through the fifth dichroic mirror 5037 is transmitted to the sixth dichroic mirror 5038, the optical pulse reflected by the sixth dichroic mirror 5038 is transmitted to the forty-first mirror 5106, the optical pulse transmitted and output from the sixth dichroic mirror 5038 is incident on the eleventh convex lens 5039, transmitted by the eleventh convex lens 5039 to the twelfth convex lens 5040, incident on the fifth grating 5042 through the twelfth convex lens 5040, the fifth grating 5042 reflects the optical pulse onto the sixth grating 5043, the sixth grating 5043 reflects the optical pulse onto the first roof mirror 5044, after the optical pulse reaches the first roof mirror 5044, it is reflected back to the fifth grating 5042 along the input route, the fifth grating 5042 transmits the optical pulse to the forty-second mirror 5041, the optical pulse is reflected by the forty-second mirror 5041 to the forty-third mirror 5045, then reflected by the forty-third mirror 5045 to the forty-fourth mirror 5046, reflected by the forty-fourth mirror 5046 to the forty-fifth mirror 5047, reflected by the forty-fifth mirror 5047 to the forty-sixth mirror 5048, reflected by the forty-sixth mirror 5048 to the knife-edge prism 5099, transmitted from the other output end of the first beam splitter 5016 to the forty-seventh mirror 5049, the optical pulse is reflected by the forty-seventh mirror 5049 to the forty-eighth mirror 5050, then reflected by the forty-eighth mirror 5050 to the forty-ninth mirror 5051, reflected by the forty-ninth mirror 5051 to the fiftieth mirror 5052, reflected by the fiftieth mirror 5052 to the fifty-first mirror 5053, the optical pulse is reflected by the fifty-first mirror 5053 to the thirteenth convex lens 5054, after the optical pulse passes through the thirteenth convex lens 5054 and the fourteenth convex lens 5055, it is reflected by the fourteenth convex lens 5055 to the seventh dichroic mirror 5056, after the optical pulse is transmitted by the seventh dichroic mirror 5056, it is fused with the optical pulse reflected after being incident on the seventh dichroic mirror 5056 along the sixty-eighth mirror 5108, the fused optical pulse is incident on the third KTiAsO4 crystal 5057 through the seventh dichroic mirror 5056, the optical pulse is transmitted by the third KTiAsO4 crystal 5057 to the eighth dichroic mirror 5058, the optical pulse reflected from the eighth dichroic mirror 5058 is reflected to the fifty-second mirror 5059, the optical pulse transmitted through the eighth dichroic mirror 5058 is transmitted to the ninth dichroic mirror 5060The optical pulse reflected by the ninth dichroic mirror 5060 is transmitted to the fifty-third mirror 5061. The optical pulse output from the ninth dichroic mirror 5060 is incident on the fifty-third mirror 5061. The optical pulse transmitted through the ninth dichroic mirror 5060 is incident on the fifty-fourth mirror 5062, reflected by the fifty-fourth mirror 5062 to the fifty-fifth mirror 5063, and then reflected by the fifty-fifth mirror 5063 to the fifteenth convex lens 5064. After passing through the fifteenth convex lens 5064 and the sixteenth convex lens 5065, the optical pulse is incident on the fifty-sixth mirror 5066, reflected by the fifty-sixth mirror 5066 to the fifty-seventh mirror 5067, reflected by the fifty-seventh mirror 5067 to the fifty-eighth mirror 5068, reflected by the fifty-eighth mirror 568 to the fifty-ninth mirror 5069, reflected by the fifty-ninth mirror 5069 to the tenth dichroic mirror 5070, and transmitted and output through the tenth dichroic mirror 5070. The optical pulse is fused with the optical pulse reflected by the sixty-ninth mirror 5098 to the tenth dichroic mirror 5070 and then reflected and output, and is incident on the fourth KTiAsO4 crystal 5071. The optical pulse is transmitted through the fourth KTiAsO4 crystal 5071 to the eleventh dichroic mirror 5072. The optical pulse reflected from the eleventh dichroic mirror 5072 is transmitted to the sixtieth mirror 5073. The optical pulse transmitted through the eleventh dichroic mirror 5072 is transmitted to the twelfth dichroic mirror 5074. The optical pulse reflected by the twelfth dichroic mirror 5074 is transmitted to the sixty-first mirror 5075. The optical pulse transmitted through the twelfth dichroic mirror 5074 is incident on the seventeenth convex lens 5076, transmitted through the eighteenth convex lens 5076 to the eighteenth convex lens 5077, and incident on the seventh grating 5078. The seventh grating 5078 reflects the optical pulse onto the eighth grating 5079. The eighth grating 5079 reflects the optical pulse onto the second roof mirror 5080. After reaching the second roof mirror 5080, the optical pulse is reflected back to the seventh grating 5078 along the input route. The seventh grating 5078 transmits the optical pulse to the sixty-second mirror 5081. After being reflected by the sixty-second mirror 5081 to the sixty-third mirror 5082, the optical pulse is reflected by the sixty-third mirror 5082 to the sixty-fourth mirror 5083, reflected by the sixty-fourth mirror 5083 to the knife-edge prism 5099. The optical pulse pumped by the laser 5084 is transmitted to the thirteenth dichroic mirror 5085. The optical pulse reflected from the thirteenth dichroic mirror 5085 passes through the eighth half-wave plate 5086 and is incident on the first thin-film polarizer 5087. The parallel polarized optical pulse transmitted through the first thin-film polarizer 5087 is incident on the sixty-fifth mirror 5107. The optical pulse is reflected by the sixty-fifth mirror 5107 to the first dichroic mirror 5023. The vertically polarized optical pulse reflected by the first thin-film polarizer 5087 is incident on the second thin-film polarizer 5088. After being reflected by the second thin-film polarizer 5088, the optical pulse passes through the ninth half-wave plate 5089 and the third erbium-doped fiber 5090 and is transmitted to the sixty-sixth mirror 5091.The optical pulse is reflected by the 66th mirror 5091 to the 4th dichroic mirror 5035. The optical pulse reflected by the 4th dichroic mirror 5035 is fused with the optical pulse that is incident on the 4th dichroic mirror 5035 through the 39th mirror 5034 and then transmitted and output by the 4th dichroic mirror 5035. The fused optical pulse is incident on the 2nd KTiAsO4 crystal 5036. The optical pulse output from the 13th dichroic mirror 5085 is transmitted by the 67th mirror 5092 to the 10th half-wave plate 5093. The optical pulse is incident on the 3rd thin-film polarizer 5094 through the 10th half-wave plate 5093. The parallel polarized optical pulse transmitted and output by the 3rd thin-film polarizer 5094 is incident on the 68th mirror 5108. The optical pulse is reflected by the 68th mirror 5108 to the 7th dichroic mirror 5056. The vertically polarized optical pulse reflected by the 3rd thin-film polarizer 5094 is incident on the 4th thin-film polarizer 5095. The optical pulse is reflected by the 4th thin-film polarizer 4080 and then transmitted through the 11th half-wave plate 5096 and the 4th erbium-doped fiber 5097 to the 69th mirror 5098. The optical pulse is reflected by the 69th mirror 5098 to the 10th dichroic mirror 5070, and finally the two identical optical pulses incident on the knife-edge prism 5099 are transmitted to the 70th mirror 5100. The optical pulse is reflected by the 70th mirror 5100 and then reflected by the 71st mirror 5101 to the CaF2 lens 5102. The two optical pulses are fused by the CaF2 lens 5102 and then output;

[0014] The polarization pulse coherent superposition module 6 has the following optical path structure. The optical pulse is incident on the 5th polarization beam splitter 601. The optical pulse is output from the output end of the 5th polarization beam splitter 601 in the direction perpendicular to the incident direction. The optical pulse is reflected by the 72nd mirror 602 to the 73rd mirror 603, reflected by the 73rd mirror 603 to the 74th mirror 604, reflected by the 74th mirror 604 to the 75th mirror 605, and then reflected back to the 5th polarization beam splitter 601 by the 75th mirror 605, and is output from the output end of the 5th polarization beam splitter 601 in the direction parallel to the incident direction. After being output by the 5th polarization beam splitter 601, the optical pulse is transmitted through the 12th half-wave plate 606 to the 6th polarization beam splitter 607. The optical pulse is transmitted to the 76th mirror 608 along the output end of the 6th polarization beam splitter 607 perpendicular to the incident direction. The optical pulse is reflected by the 76th mirror 608 to the 77th mirror 609, reflected by the 77th mirror 609 to the 78th mirror 610, reflected by the 78th mirror 610 to the 79th mirror 611, and then reflected back to the 6th polarization beam splitter 607 by the 79th mirror 611. The optical pulse is output from the other output end parallel to the incident direction of the 6th polarization beam splitter 607. The optical pulse is transmitted through the 6th polarization beam splitter to the 13th half-wave plate 612, transmitted through the 13th half-wave plate 612 to the 7th polarization beam splitter 613, and finally output by the 7th polarization beam splitter 613;

[0015] The second-order pulse width compression module 7 has the following beam structure. An optical pulse is incident on the ninth grating 701, and the optical pulse output from the ninth grating 701 passes through the nineteenth convex lens 702, the optical slit 703, and the twentieth convex lens 704 and then is incident on the tenth grating 705. The optical pulse output from the tenth grating 705 passes through the eighth quarter-wave plate 706 and is incident on the eightieth mirror 707. After the optical pulse reaches the eightieth mirror 707, it returns along the original path to the ninth grating 701. The optical pulse output from the ninth grating 701 passes through the thermally filled hollow-core fiber 708 and is incident on the eleventh grating 709. The optical pulse is reflected by the eleventh grating 709 to the twelfth grating 710, and is reflected by the twelfth grating 710 to the first fused silica plate 711. The optical pulse passes through the first fused silica plate 711 and the BBO crystal 712 and then is incident on the first chirped mirror 713. The optical pulse is reflected by the first chirped mirror 713 to the second chirped mirror 714, and then is reflected back to the first chirped mirror 713 by the second chirped mirror 714. After the optical pulse is reflected multiple times between the first chirped mirror 713 and the second chirped mirror 714, it returns to the second chirped mirror 714. The optical pulse is transmitted by the second chirped mirror 714 to the eighty-first mirror 715, is reflected by the eighty-first mirror 715 to the second fused silica plate 716, and is incident on the aluminum D-shaped split mirror 717 through the second fused silica plate 716. The optical pulse output from the D-shaped split mirror 717 is incident on the eighty-second mirror 718. The optical pulse is reflected by the eighty-second mirror 718 to the eighty-third mirror 719, and is reflected by the eighty-third mirror 719 to the second concave mirror 720. Then, the optical pulse is transmitted by the second concave mirror 720 to the third fused silica plate 723. The optical pulse output from the other end of the D-shaped split mirror 717 is transmitted to the eighty-fourth mirror 721, is reflected by the eighty-fourth mirror 721 to the eighty-fifth mirror 722, and is reflected by the eighty-fifth mirror 722 to the second concave mirror 720. Then, it is transmitted by the second concave mirror 720 to the third fused silica plate 723. The residual light beam passing through the third fused silica plate 723 is incident on the beam blocker 724, and the optical pulse passing through the third fused silica plate 723 is finally output by the twenty-first convex lens 725.

[0016] Beneficial effects:

[0017] 1. The present invention uses a phase-shifted long-period grating to design a tunable passband filter and combines it with a birefringent Sagnac filter to tune and control the wavelength in the laser cavity, realizing multi-wavelength pulse output.

[0018] 2. The present invention uses a grating pair and an optical lens to design a narrowband spectral filter, realizing ultrashort pulse output.

[0019] 3. The present invention uses a spatial optical lens to design a multi-channel polarization pulse splitting and integrating structure, effectively improving the pulse power of the system.

[0020] 4. The present invention uses a non-linear crystal, barium metaborate, to design a central wavelength shift structure for non-linear frequency conversion, thereby achieving deep ultraviolet pulse output. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the overall structural block diagram of the present invention.

[0022] Figure 2 is the optical path diagram of the seed pulse source module used in the present invention.

[0023] Figure 3 is the optical path diagram of the pulse width broadening module used in the present invention.

[0024] Figure 4 is the optical path diagram of the pulse pick-up module used in the present invention.

[0025] Figure 5 is the optical path diagram of the pulse time domain division module used in the present invention.

[0026] Figure 6 is the optical path diagram of the first-stage pulse width compression module used in the present invention.

[0027] Figure 7 is the optical path diagram of the polarization pulse coherent superposition module used in the present invention.

[0028] Figure 8 is the optical path diagram of the second-stage pulse width compression module used in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] The working principle of the present invention will be further described below with reference to the accompanying drawings. It should be understood that the parameters of each component marked in the embodiments are preferred parameters, rather than a limitation on the protection scope.

[0030] Embodiment 1 Overall Structure of the Present Invention

[0031] As Figure 1 shown, the overall structure of the present invention is as follows: the output end of the seed pulse source 1 is connected to the input end of the pulse width broadening module 2, the output end of the pulse width broadening module 2 is connected to the input end of the pulse pick-up module 3, the output end of the pulse pick-up module 3 is connected to the input end of the pulse time domain division module 4, the output end of the pulse time domain division module 4 is connected to the input end of the first-stage pulse width compression module 5, the output end of the first-stage pulse width compression module 5 is connected to the input end of the polarization pulse coherent superposition module 6, and the output end of the polarization pulse coherent superposition module 6 is connected to the input end of the second-stage pulse width compression module 7.

[0032] Embodiment 2 Seed Pulse Source Module

[0033] The structure of the seed pulse source module is as follows: The pump source 101 (LC962U type pump source, with a central wavelength of 980 nm and a maximum single-mode output optical power of 750 mW) is connected to the 980 nm end of the wavelength division multiplexer 102 (980 / 1060 nm single-mode fiber wavelength division multiplexer). The 1550 nm end of the wavelength division multiplexer 102 is connected to the input end of the first isolator 103 (HOI-005-532 isolator). The output end of the first isolator 103 is connected to the input end of the second isolator 105 (HOI-005-532 isolator) through the erbium-doped fiber 104 (Er80-4 / 125 erbium-doped fiber). The output end of the second isolator 105 is connected to the input end of the filter 106. The output end of the filter 106 (CW4L2 filter) is connected to the input end of the first polarization controller 107. The output end of the first polarization controller 107 is connected to the input end of the first collimator 109 (M011 collimator) through the single-mode fiber 108 (Lucent 980). The optical pulse passes through the first collimator 109, the first half-wave plate 110 (WPZ2310-248 half-wave plate), the first quarter-wave plate 111 (WPZ4310-248 quarter-wave plate), the first polarization-sensitive isolator 112 (714 polarization-sensitive isolator), the first polarization beam splitter 113 (QTFBC-1216 polarization beam splitter), and the second quarter-wave plate 114 (WPZ4310-248 quarter-wave plate) and then is transmitted to the second collimator 115 (M011 collimator). The second collimator 115 is connected to the input end of the first coupler 117 (FUSED-12-1060-7 / 125-50 / 50-3U-3mm fiber coupler) through the phase-shifted long-period grating 116. The direct output end of the first coupler 117 is connected to the common end of the wavelength division multiplexer 102. The coupled output end of the first coupler 117 is connected to the input end of the second polarization controller 120. The output end of the second polarization controller 120 is connected to the output end of the third polarization controller 118 through the polarization-maintaining fiber 119. The input end of the third polarization controller 118 is connected to the other input end of the first coupler 117. The output end of the first polarization beam splitter 113 in the vertical incident direction serves as the output of the seed pulse source module. The above structure constitutes a multi-wavelength tunable mode-locked fiber laser resonator.

[0034] Example 3 Pulse Width Broadening Module

[0035] The pulse width broadening module 2 has the following optical path structure. The optical pulse is transmitted to the first grating 202 (T-1702-1030s) through the first mirror 201 (GMH12-005-AU mirror). After the first grating 202 transmits the optical pulse to the second mirror 203 (GMH12-005-AU mirror), it is reflected to the third mirror 204 (GMH12-005-AU mirror). The third mirror 204 reflects the optical pulse back to the first grating 202. The pulse output by the first grating 202 is transmitted to the fourth mirror 206 (GMH12-005-AU mirror) through the first convex lens 205 (GLH12-002-002-NIR convex lens) and then reflected back to the first grating 202 by the first convex lens 205. The optical pulse is transmitted to the second mirror 203 through the first grating 202. The second mirror 203 reflects the optical pulse and after being reflected by the third mirror 204, it is incident on the first grating 202. The optical pulse output by the first grating 202 is incident on the Porro prism 207 (POP0012-5 Porro prism) and is reflected back to the first grating 202 by the Porro prism 207. The optical pulse is transmitted to the second mirror 203 after passing through the first grating 202, and then reflected to the third mirror 204. The third mirror 204 reflects the optical pulse back to the first grating 202. After being output by the first grating 202, it is transmitted to the fourth mirror 206 through the first convex lens 205. After being reflected by the fourth mirror 206, it is transmitted to the first grating 202 through the first convex lens 205 again. It is transmitted to the second mirror 203 through the first grating 202, and then reflected to the third mirror 204. The third mirror 204 reflects the optical pulse back to the first grating 202. It is transmitted to the Porro prism 207 through the first grating 202 and is reflected back to the first grating 202 by the Porro prism 207, and finally output by the first grating 202. The pulse width broadening module broadens the pulse width of the optical pulse.

[0036] Example 4 Pulse Pickup Module

[0037] The optical pulse passes through the second convex lens 301, the acousto-optic modulator 302 (Fiber-Q acousto-optic modulator), the third convex lens 303 (GLH12-002-002-NIR convex lens), the third isolator 304 (HOI-005-532 isolator), and the second half-wave plate 305 (WPZ3240-248 half-wave plate), and then is incident on the fifth mirror 306 (GMH12-005-AU mirror). The optical pulse is reflected by the fifth mirror 306 to the sixth mirror 307 (GMH12-005-AU mirror) and then is incident on the fourth convex lens 308 (GLH12-002-002-NIR convex lens). The optical pulse passes through the fourth convex lens 308, the third collimator 309 (M011 collimator), the second erbium-doped fiber 310 (Er80-4 / 125 erbium-doped fiber), the fourth collimator 311 (M011 collimator), and the fifth convex lens 312 (GLH12-002-002-NIR convex lens), and then is incident on the seventh mirror 313 (GMH12-005-AU mirror). The pump light generated by the first photodiode 316 (D4F2P22-976 photodiode) passes through the fifth collimator 315 (M011 collimator) and the sixth convex lens 314 (GLH12-002-002-NIR convex lens), and then is fused with the optical pulse incident on the seventh mirror 313 via the fourth collimator 311 and the fifth convex lens 312. The fused optical pulse is reflected by the seventh mirror 313 to the eighth mirror 317 (GMH12-005-AU mirror). The eighth mirror 317 reflects the optical pulse to the third half-wave plate 318 (WPZ3240-248 half-wave plate). The optical pulse passes through the third half-wave plate 318, the third quarter-wave plate 319 (WPZ4310-248 quarter-wave plate), the band-pass filter 320 (CW4L2 filter), and the fourth half-wave plate 321 (WPZ3240-248 half-wave plate), and then is incident on the second grating 325 (LSFSG-1000-3318-94 grating). The optical pulse is transmitted by the second grating 325 to the third grating 326 (LSFSG-1000-3318-94 grating). The third grating 326 transmits the optical pulse to the ninth mirror 327 (GMH12-005-AU mirror). The ninth mirror 327 reflects the pulse back to the third grating 326, and the optical pulse is transmitted by the third grating 326 to the second grating 325. The optical pulse output by the second grating 325 is transmitted to the tenth mirror 322 (GMH12-005-AU mirror) and is reflected by the tenth mirror 322 into the fifth half-wave plate 323 (WPZ3240-248 half-wave plate), and finally is output through the second polarization beam splitter 324 (QTFBC-1309 polarization beam splitter); the pulse pick-up module 3 reduces the pulse repetition frequency and performs pre-shaping to compensate for the loss caused by placing the acousto-optic modulator in the configuration.

[0038] Embodiment 5 Pulse Time Domain Segmentation Module

[0039] The pulse time domain segmentation module 4 has the following optical path structure. The optical pulse is incident on the input end of the third polarization beam splitter 402 (QTFBC-1216 polarization beam splitter) through the sixth half-wave plate 401 (WPZ2410-248 half-wave plate). The optical pulse is output from the output end of the third polarization beam splitter 402 in the direction perpendicular to the incident direction and is transmitted through the fourth quarter-wave plate 403 (WPZ4410-248 quarter-wave plate) to the eleventh mirror 404 (GMH12-005-AU mirror). The eleventh mirror 404 reflects the optical pulse back to the fourth quarter-wave plate 403, and the fourth quarter-wave plate 403 transmits the optical pulse to the third polarization beam splitter 402 again. At the same time, the optical pulse is output from another output end of the third polarization beam splitter 402 perpendicular to the incident direction and is transmitted through the fifth quarter-wave plate 405 to the twelfth mirror 406 (GMH12-005-AU mirror) and the first piezoelectric actuator 407. Then the optical pulse is reflected back to the fifth quarter-wave plate 405 (WPZ4410-248 quarter-wave plate) by the twelfth mirror 406, and the fifth quarter-wave plate 405 transmits the optical pulse back to the third polarization beam splitter 402 again. The optical pulse is output from the port of the third polarization beam splitter 402 parallel to the incident direction and is transmitted through the seventh half-wave plate 408 (WPZ2410-248 half-wave plate) to the fourth polarization beam splitter 409 (QTFBC-1216 polarization beam splitter). The optical pulse passes through the sixth quarter-wave plate 410 (WPZ4410-248 quarter-wave plate) from the port of the fourth polarization beam splitter 409 perpendicular to the incident direction and is transmitted to the thirteenth mirror 411 (GMH12-005-AU mirror). The thirteenth mirror 411 reflects the optical pulse back to the sixth quarter-wave plate 410, and the sixth quarter-wave plate 410 transmits the optical pulse back to the fourth polarization beam splitter 409 again. At the same time, the optical pulse passes through the seventh quarter-wave plate 412 (WPZ4410-248 quarter-wave plate) from another port of the fourth polarization beam splitter 409 perpendicular to the incident direction and is transmitted to the fourteenth mirror 413 (GMH12-005-AU mirror) and the second piezoelectric actuator 414. Then the optical pulse is reflected back to the seventh quarter-wave plate 412 by the fourteenth mirror 413, and the seventh quarter-wave plate 412 transmits the optical pulse to the fourth polarization beam splitter 409 again. The optical pulse is output from the output end of the fourth polarization beam splitter 409 parallel to the incident direction.

[0040] Embodiment 6 First-stage Pulse Width Compression Module

[0041] The first-stage pulse width compression module 5 has the following optical path structure. The optical pulse is transmitted to the fourth grating 5001 (LSFSG-1000-5085-94 grating). The optical pulse is reflected by the fourth grating 5001 to the first concave mirror 5002 (GMH-13 concave mirror). The first concave mirror 5002 reflects the optical pulse to the fifteenth mirror 5003 (GMH12-0050-AU mirror). After the optical pulse is reflected by the fifteenth mirror 5003 and then reflected by the first concave mirror 5002, it is transmitted to the fourth grating 5001 through the first concave mirror 5002. After passing through the fourth grating 5001, the optical pulse is transmitted through the first concave mirror 5002 and the fifteenth mirror 5003 again along the route described above. After multiple reflections, the optical pulse returns to the fourth grating 5001. The fourth grating 5001 reflects the optical pulse to the sixteenth mirror 5004 (GMH12-0050-AU mirror). The optical pulse is transmitted by the sixteenth mirror 5004 to the seventeenth mirror 5005 (GMH12-0050-AU mirror), transmitted by the seventeenth mirror 5005 to the eighteenth mirror 5006 (GMH12-0050-AU mirror), and transmitted by the eighteenth mirror 5006 to the nineteenth mirror 5007 (GMH12-0050-AU mirror). Then, the optical pulse undergoes spectral shaping through seven mirrors in sequence: The optical pulse passes through the twentieth mirror 5008 (GMH12-0050-AU mirror), the twenty-first mirror 5009 (GMH12-0050-AU mirror), the twenty-second mirror 5010 (GMH12-0050-AU mirror), the twenty-third mirror 5011 (GMH12-0050-AU mirror), the twenty-fourth mirror 5012 (GMH12-0050-AU mirror), the twenty-fifth mirror 5013 (GMH12-0050-AU mirror), and the twenty-sixth mirror 5014 (GMH12-0050-AU mirror) in sequence. After being reflected, the optical pulse is incident on the twenty-seventh mirror 5015 (GMH12-0050-AU mirror). The output of the twenty-seventh mirror 5015 is the output of the polarization pulse module.The optical pulse is incident on the input end of the first beam splitter 5016 and is transmitted from the output end of the first beam splitter 5016 to the twenty-eighth mirror 5017 (GMH12-0050-AU mirror). After the optical pulse is reflected by the twenty-eighth mirror 5017 to the twenty-ninth mirror 5018 (GMH12-0050-AU mirror), it is reflected by the twenty-ninth mirror 5018 to the thirtieth mirror 5019 (GMH12-0050-AU mirror). The thirtieth mirror 5019 reflects the optical pulse to the thirty-first mirror 5020 (GMH12-0050-AU mirror). The optical pulse is reflected by the thirty-first mirror 5020 to the seventh convex lens 5021 (GLH12-002-002-NIR convex lens). After the optical pulse passes through the seventh convex lens 5021, the eighth convex lens 5022 (GLH12-002-002-NIR convex lens), and the first dichroic mirror 5023 (DMSP1180 dichroic mirror), it is transmitted and output through the first dichroic mirror 5023. The optical pulse is fused with the optical pulse that is reflected by the sixty-third mirror 5107 (GMH12-0050-AU mirror) to the first dichroic mirror 5023 and then reflected and output. The fused optical pulse is transmitted through the first dichroic mirror 5023 to the first KTiAsO4 crystal 5024 (density 3.4504 g / cm³). 3KTA), the optical pulse is transmitted through the first KTiAsO4 crystal 5024 to the second dichroic mirror 50250 (DMSP1180 dichroic mirror). The short-wavelength optical pulse reflected from the second dichroic mirror 5025 is transmitted to the thirty-second mirror 5103 (GMH12-0050-AU mirror). The long-wavelength optical pulse transmitted through the second dichroic mirror 5025 is transmitted to the third dichroic mirror 5026 (DMSP1180 dichroic mirror). The optical pulse reflected by the third dichroic mirror 5026 is transmitted to the thirty-third mirror 5104 (GMH12-0050-AU mirror). The optical pulse transmitted through the third dichroic mirror 5026 is incident on the thirty-fourth mirror 5027 (GMH12-0050-AU mirror). The optical pulse is reflected by the thirty-fourth mirror 5027 to the thirty-fifth mirror 5028 (GMH12-0050-AU mirror), reflected by the thirty-fifth mirror 5028 to the ninth convex lens 5029 (GLH12-002-002-NIR convex lens), transmitted through the ninth convex lens 5029 to the tenth convex lens 5030 (GLH12-002-002-NIR convex lens), and incident on the thirty-sixth mirror 5031 (GMH12-0050-AU mirror) after passing through the tenth convex lens 5030. The optical pulse is reflected by the thirty-sixth mirror 5031 to the thirty-seventh mirror 5032 (GMH12-0050-AU mirror), reflected by the thirty-seventh mirror 5032 to the thirty-eighth mirror 5033 (GMH12-0050-AU mirror), reflected by the thirty-eighth mirror 5033 to the thirty-ninth mirror 5034 (GMH12-0050-AU mirror), transmitted through the thirty-ninth mirror 5034 to the fourth dichroic mirror 5035 (DMSP1180 dichroic mirror), and transmitted through the fourth dichroic mirror 5035 to the second KTiAsO4 crystal 5036 (density 3.4504 g / cm 3In the KTA), the optical pulse is transmitted through the second KTiAsO4 crystal 5036 to the fifth dichroic mirror 5037 (DMSP1180 dichroic mirror). The optical pulse reflected from the fifth dichroic mirror 5037 is transmitted to the fortieth mirror 5105 (GMH12 - 0050 - AU mirror). The optical pulse transmitted through the fifth dichroic mirror 5037 is transmitted to the sixth dichroic mirror 5038 (DMSP1180 dichroic mirror). The optical pulse reflected from the sixth dichroic mirror 5038 is transmitted to the forty - first mirror 5106 (GMH12 - 0050 - AU mirror). The optical pulse transmitted and output from the sixth dichroic mirror 5038 is incident on the eleventh convex lens 5039 (GLH12 - 002 - 002 - NIR convex lens), transmitted through the eleventh convex lens 5039 to the twelfth convex lens 5040 (GLH12 - 002 - 002 - NIR convex lens), and incident on the fifth grating 5042 (LSFSG - 1000 - 32250 - 94 grating) through the twelfth convex lens 5040. The fifth grating 5042 reflects the optical pulse onto the sixth grating 5043 (LSFSG - 1000 - 32250 - 94 grating). The sixth grating 5043 reflects the optical pulse onto the first roof mirror 5044 (HS - 002103). After the optical pulse reaches the first roof mirror 5044, it is reflected back to the fifth grating 5042 along the input route. The fifth grating 5042 transmits the optical pulse to the forty - second mirror 5041 (GMH12 - 0050 - AU mirror). After the optical pulse is reflected by the forty - second mirror 5041 to the forty - third mirror 5045 (GMH12 - 0050 - AU mirror), it is reflected by the forty - third mirror 5045 to the forty - fourth mirror 5046, reflected by the forty - fourth mirror 5046 (GMH12 - 0050 - AU mirror) to the forty - fifth mirror 5047 (GMH12 - 0050 - AU mirror), reflected by the forty - fifth mirror 5047 to the forty - sixth mirror 5048 (GMH12 - 0050 - AU mirror), reflected by the forty - sixth mirror 5048 to the knife - edge prism 5099, and transmitted from the other output end of the first beam splitter 5016 to the forty - seventh mirror 5049 (GMH12 - 0050 - AU mirror). After the optical pulse is reflected by the forty - seventh mirror 5049 to the forty - eighth mirror 5050 (GMH12 - 0050 - AU mirror), it is reflected by the forty - eighth mirror 5050 to the forty - ninth mirror 5051, reflected by the forty - ninth mirror 5051 (GMH12 - 0050 - AU mirror) to the fiftieth mirror 5052 (GMH12 - 0050 - AU mirror), reflected by the fiftieth mirror 5052 to the fifty - first mirror 5053 (GMH12 - 0050 - AU mirror). The optical pulse is reflected by the fifty - first mirror 5053 to the thirteenth convex lens 5054 (GLH12 - 002 - 002 - NIR convex lens).After the optical pulse passes through the thirteenth convex lens 5054 and the fourteenth convex lens 5055 (GLH12-002-002-NIR convex lens), it is reflected by the fourteenth convex lens 5055 to the seventh dichroic mirror 5056 (DMSP1180 dichroic mirror). After the optical pulse is transmitted through the seventh dichroic mirror 5056, it is fused with the optical pulse that is incident on the seventh dichroic mirror 5056 along the sixty-eighth mirror 5108 (GMH12-0050-AU mirror) and then reflected out. The fused optical pulse is incident on the seventh dichroic mirror 5056 and then enters the third KTiAsO4 crystal 5057 (density 3.4504 g / cm, 3 KTA crystal). The optical pulse is transmitted through the third KTiAsO4 crystal 5057 to the eighth dichroic mirror 5058 (DMSP1180 dichroic mirror). The optical pulse reflected from the eighth dichroic mirror 5058 is reflected to the fifty-second mirror 5059 (GMH12-0050-AU mirror). The optical pulse transmitted through the eighth dichroic mirror 5058 is transmitted to the ninth dichroic mirror 5060 (DMSP1180 dichroic mirror). The optical pulse reflected by the ninth dichroic mirror 5060 is transmitted to the fifty-third mirror 5061 (GMH12-0050-AU mirror). The optical pulse output from the ninth dichroic mirror 5060 is incident on the fifty-third mirror 5061. The optical pulse transmitted through the ninth dichroic mirror 5060 is incident on the fifty-fourth mirror 5062 (GMH12-0050-AU mirror). It is reflected by the fifty-fourth mirror 5062 to the fifty-fifth mirror 5063 (GMH12-0050-AU mirror). After being reflected by the fifty-fifth mirror 5063 to the fifteenth convex lens 5064 (GLH12-002-002-NIR convex lens), the optical pulse passes through the fifteenth convex lens 5064 and the sixteenth convex lens 50650 (GLH12-002-002-NIR convex lens), and is incident on the fifty-sixth mirror 5066 (GMH12-0050-AU mirror). The optical pulse is reflected by the fifty-sixth mirror 5066 to the fifty-seventh mirror 5067 (GMH12-0050-AU mirror). After being reflected by the fifty-seventh mirror 5067 to the fifty-eighth mirror 5068 (GMH12-0050-AU mirror), it is reflected by the fifty-eighth mirror 5068 to the fifty-ninth mirror 5069. After being reflected by the fifty-ninth mirror 5069 (GMH12-0050-AU mirror) to the tenth dichroic mirror 5070 (DMSP1180 dichroic mirror), it is transmitted and output. The optical pulse is fused with the optical pulse that is reflected by the sixty-ninth mirror 5098 (GMH12-0050-AU mirror) to the tenth dichroic mirror 5070 and then reflected and output, and then enters the fourth KTiAsO4 crystal 5070. The optical pulse passes through the fourth KTiAsO4 crystal 5071 (density 3.4504 g / cm 3The light pulse of the KTA crystal is transmitted to the eleventh dichroic mirror 5072 (DMSP1180 dichroic mirror). The light pulse reflected from the eleventh dichroic mirror 5072 is transmitted to the sixtieth mirror 5073 (GMH12-0050-AU mirror). The light pulse transmitted through the eleventh dichroic mirror 5072 is transmitted to the twelfth dichroic mirror 5074 (DMSP1180 dichroic mirror). The light pulse reflected by the twelfth dichroic mirror 5074 is transmitted to the sixty-first mirror 5075 (GMH12-0050-AU mirror). The light pulse transmitted through the twelfth dichroic mirror 5074 is incident on the seventeenth convex lens 5076 (GLH12-002-002-NIR convex lens). After being transmitted through the seventeenth convex lens 5076 (GLH12-002-002-NIR convex lens), it is transmitted to the eighteenth convex lens 5077 (GLH12-002-002-NIR convex lens). After passing through the eighteenth convex lens 5077, it is incident on the seventh grating 5078 (LSFSG-1000-32250-94 grating). The seventh grating 5078 reflects the light pulse onto the eighth grating 5079 (LSFSG-1000-32250-94 grating). The eighth grating 5079 reflects the light pulse onto the second roof mirror 5080 (HS-002103). After the light pulse reaches the second roof mirror 5080, it is reflected back to the seventh grating 5078 along the input route. The seventh grating 5078 transmits the light pulse to the sixty-second mirror 5081 (GMH12-0050-AU mirror). After the light pulse is reflected by the sixty-second mirror 5081 to the sixty-third mirror 5082 (GMH12-0050-AU mirror), it is then reflected by the sixty-third mirror 5082 to the sixty-fourth mirror 5083 (GMH12-0050-AU mirror). After being reflected by the sixty-fourth mirror 5083, it is transmitted to the knife-edge prism 4084. The light pulse pumped by the laser 5084 (APL 21050 commercial picosecond Nd:YAG laser) is transmitted to the thirteenth dichroic mirror 5085 (DMSP1180 dichroic mirror). The light pulse reflected from the thirteenth dichroic mirror 5085 passes through the eighth half-wave plate 5086 (WPZ2310-248 half-wave plate) and is incident on the first thin-film polarizer 5087. The parallel polarized light pulse transmitted through the first thin-film polarizer 5087 is incident on the sixty-fifth mirror 5107 (GMH12-0050-AU mirror). The light pulse is reflected by the sixty-fifth mirror 5107 to the first dichroic mirror 5023. The vertically polarized light pulse reflected by the first thin-film polarizer 5087 is incident on the second thin-film polarizer 5088. After the light pulse is reflected by the second thin-film polarizer 5088, it passes through the ninth half-wave plate 5089 (WPZ2310-248 half-wave plate) and the third erbium-doped fiber 5090 (Er80-4 / 1250 erbium-doped fiber) and is transmitted to the sixty-sixth mirror 5091 (GMH12-0050-AU mirror).The optical pulse is reflected by the 66th mirror 4076 to the 4th dichroic mirror 5035. The optical pulse reflected by the 4th dichroic mirror 5035 is fused with the optical pulse that is incident on the 4th dichroic mirror 5035 through the 39th mirror 5034 and then transmitted and output by the 4th dichroic mirror 5035. The fused optical pulse is incident on the 2nd KTiAsO4 crystal 5036. The optical pulse output from the 13th dichroic mirror 5085 is transmitted by the 67th mirror 4092 (GMH12-0050-AU mirror) to the 10th half-wave plate 5093 (WPZ2310-248 half-wave plate). The optical pulse is incident on the 3rd thin-film polarizer 5094 through the 10th half-wave plate 5093. The parallel polarized optical pulse transmitted and output by the 3rd thin-film polarizer 5094 is incident on the 68th mirror 5108 (GMH12-0050-AU mirror). The optical pulse is reflected by the 68th mirror 4106 to the 7th dichroic mirror 5056. The vertically polarized optical pulse reflected by the 3rd thin-film polarizer 5094 is incident on the 4th thin-film polarizer 5095. The optical pulse is reflected by the 4th thin-film polarizer 5095 and then transmitted through the 11th half-wave plate 5096 (WPZ2310-248 half-wave plate) and the 4th erbium-doped fiber 5097 (Er80-4 / 125 erbium-doped fiber) to the 69th mirror 5098 (GMH12-005-AU mirror). The optical pulse is reflected by the 69th mirror 5098 to the 10th dichroic mirror 5070. Finally, two optical pulses with the same characteristics such as energy and pulse duration are incident on the knife-edge prism 5099. The two optical pulses are transmitted by the knife-edge prism 5099 to the 70th mirror 5100 (GMH12-005-AU mirror). The optical pulse is reflected by the 70th mirror 5100 to the 71st mirror 5101 (GMH12-005-AU mirror) and then reflected to the CaF2 lens 5102 (GWH51-012). The two optical pulses are fused by the CaF2 lens 5102 and then output. The first-stage pulse width compression module performs multi-channel power amplification and pulse width compression on the pulse.,

[0042] Example 7 Polarization Pulse Coherent Superposition Module

[0043] The polarization pulse coherent superposition module 6 has the following optical path structure. An optical pulse is incident on a fifth polarization beam splitter 601 (QTFBC-1216 polarization beam splitter). The optical pulse is output from the output end of the fifth polarization beam splitter 601 in the direction perpendicular to the incident direction. The optical pulse is reflected by a seventy-second mirror 602 (GMH12-005-AU mirror) to a seventy-third mirror 603 (GMH12-005-AU mirror), reflected by the seventy-third mirror 603 to a seventy-fourth mirror 604 (GMH12-005-AU mirror), reflected by the seventy-fourth mirror 604 to a seventy-fifth mirror 605 (GMH12-005-AU mirror), and after being reflected back to the fifth polarization beam splitter 601 by the seventy-fifth mirror 605, it is output from the output end of the fifth polarization beam splitter 601 in the direction parallel to the incident direction. After being output by the fifth polarization beam splitter 601, the optical pulse is transmitted through a twelfth half-wave plate 606 (WPZ2310-248 half-wave plate) to a sixth polarization beam splitter 607 (QTFBC-1216 polarization beam splitter). The optical pulse is transmitted to a seventy-sixth mirror 608 (GMH12-005-AU mirror) along the output end of the sixth polarization beam splitter 607 perpendicular to the incident direction. The optical pulse is reflected by the seventy-sixth mirror 608 to a seventy-seventh mirror 609 (GMH12-005-AU mirror), reflected by the seventy-seventh mirror 609 to a seventy-eighth mirror 610 (GMH12-005-AU mirror), reflected by the seventy-eighth mirror 610 to a seventy-ninth mirror 611 (GMH12-005-AU mirror), and after being reflected back to the sixth polarization beam splitter 607 by the seventy-ninth mirror 611, the optical pulse is output from another output end parallel to the incident direction of the sixth polarization beam splitter 607. The optical pulse is transmitted through the sixth polarization beam splitter to a thirteenth half-wave plate 612 (WPZ2310-248 half-wave plate), and then transmitted through the thirteenth half-wave plate 612 to a seventh polarization beam splitter 613 (QTFBC-1216 polarization beam splitter), and finally output by the seventh polarization beam splitter 613.

[0044] Embodiment 8 Second-order Pulse Width Compression Module

[0045] The second-order pulse width compression module 7 has the following beam structure. The optical pulse is incident on the ninth grating 701 (LSFSG-1000-3225-94 grating). The optical pulse output from the ninth grating 701 passes through the nineteenth convex lens 702 (GLH12-002-002-NIR convex lens), the optical slit 703 (S170LK), and the twentieth convex lens 704 (GLH12-002-002-NIR convex lens) and then is incident on the tenth grating 705 (LSFSG-1000-3225-94 grating). The optical pulse output from the tenth grating 705 passes through the eighth quarter-wave plate 706 (WPZ4310-248 quarter-wave plate) and is incident on the eightieth mirror 707 (GMH12-005-AU mirror). After the optical pulse reaches the eightieth mirror 707, it returns along the original path to the ninth grating 701. The optical pulse output from the ninth grating 701 passes through the thermally filled hollow-core fiber 708 (HC-1570-02) and is incident on the eleventh grating 709 (LSFSG-1000-3225-94 grating). The optical pulse is reflected by the eleventh grating 709 to the twelfth grating 710 and is reflected by the twelfth grating 710 (LSFSG-1000-3225-94 grating) to the first fused silica plate 711 (5.75 mm). The optical pulse passes through the first fused silica plate 711 and the BBO crystal 712 (29.After passing through a 2-μm-thick type-I phase-matching BBO crystal, the light pulse is incident on the first chirped mirror 713 (CM82). After being reflected by the first chirped mirror 713 and then reaching the second chirped mirror 714, it is reflected back to the first chirped mirror 713 by the second chirped mirror 714. After multiple reflections between the first chirped mirror 713 and the second chirped mirror 714, the light pulse returns to the second chirped mirror 714 (CM82). The light pulse is transmitted by the second chirped mirror 714 to the eighty-first mirror 715 (GMH12-005-AU mirror), reflected by the eighty-first mirror 715 to the second fused silica plate 716 (70 μm), incident on the aluminum D-shaped split mirror 717 (HBS12-012-30-PD) through the second fused silica plate 716. The light pulse output from the D-shaped split mirror 717 is incident on the eighty-second mirror 718 (GMH12-005-AU mirror), reflected by the eighty-second mirror 718 to the eighty-third mirror 719 (GMH12-005-AU mirror), and then reflected by the eighty-third mirror 719 to the second concave mirror 720 (GMH-13 concave mirror). After that, the light pulse is transmitted by the second concave mirror 720 to the third fused silica plate 723 (70 μm). The light pulse output from the other end of the D-shaped split mirror 717 is transmitted to the eighty-fourth mirror 721 (GMH12-005-AU mirror), reflected by the eighty-fourth mirror 721 to the eighty-fifth mirror 722 (GMH12-005-AU mirror), and then reflected by the eighty-fifth mirror 722 to the second concave mirror 720, and then transmitted by the second concave mirror 720 to the third fused silica plate 723. The residual light beam passing through the third fused silica plate 723 is incident on the beam blocker 724 (PD300-IR), and the light pulse passing through the third fused silica plate 723 is finally output by the twenty-first convex lens 725 (GLH12-002-002-NIR convex lens). The second-order pulse width compression module 7 realizes further pulse width compression and central wavelength shift.

[0046] Example 9 Working principle of the present invention

[0047] Combined with the above embodiments and each drawing, the working principle of the present invention is described.

[0048] In the seed pulse source module 1, the phase-shifted long-period grating 116, the filter 106, and the birefringent Sagnac filter structure composed of the second polarization controller 120, the third polarization controller 118, and the polarization-maintaining fiber 119 can tune and control the laser to achieve multi-wavelength pulse output. The pulse pick-up module 3 compresses the spectral width of the pulse to prevent the amplified pulse from damaging the amplification device. The acousto-optic modulator 302 can reduce the optical pulse repetition frequency so as to obtain higher pulse energy in the subsequent structure. The spectral shaping structure composed of a grating and an optical lens can perform pre-shaping to compensate for the gain narrowing effect generated during the amplification process and achieve the output of ultrashort pulses. The first-stage pulse width compression module 5 uses a multi-path pulse amplification and pulse width compression structure for effective power amplification and pulse width compression. A narrowband spectral filter composed of a grating pair, an optical lens, and an optical slit is used to further compress the pulse width to obtain ultrashort pulse output. Finally, frequency conversion is achieved through the nonlinear crystal barium metaborate to realize the output of deep ultraviolet ultrashort pulses.

Claims

1. An ultrashort pulse source for a dense wavelength division multiplexing system, whose structure is as follows: the output end of a seed pulse source (1) is connected to the input end of a pulse width broadening module (2), the output end of the pulse width broadening module (2) is connected to the input end of a pulse picking module (3), the output end of the pulse picking module (3) is connected to the input end of a pulse time domain segmentation module (4), the output end of the pulse time domain segmentation module (4) is connected to the input end of a first-stage pulse width compression module (5), the output end of the first-stage pulse width compression module (5) is connected to the input end of a polarization pulse coherent superposition module (6), and the output end of the polarization pulse coherent superposition module (6) is connected to the input end of a second-stage pulse width compression module (7); The structure of the seed pulse source module (1) is as follows: a pump source (101) is connected to the 980 nm end of a wavelength division multiplexer (102), the 1550 nm end of the wavelength division multiplexer (102) is connected to the input end of a first isolator (103), the output end of the first isolator (103) is connected to the input end of an erbium-doped fiber (104) through a second isolator (105), the output end of the second isolator (105) is connected to the input end of a filter (106), the output end of the filter (106) is connected to the input end of a first polarization controller (107), the output end of the first polarization controller (107) is connected to the input end of a first collimator (109) through a single-mode fiber (108), an optical pulse is transmitted to a second collimator (115) after passing through the first collimator (109), a first half-wave plate (110), a first quarter-wave plate (111), a first polarization-sensitive isolator (112), a first polarization beam splitter (113), and a second quarter-wave plate (114). The second collimator (115) is connected to the input end of a second coupler (117) through a phase-shifted long-period grating (116). The direct output end of the second coupler (117) is connected to the common end of the wavelength division multiplexer (102), and the coupled output end of the second coupler (117) is connected to the input end of a second polarization controller (120). The output end of the second polarization controller (120) is connected to the output end of a third polarization controller (118) through a polarization-maintaining fiber (119), and the input end of the third polarization controller (118) is connected to the other input end of the second coupler (117). The output end of the first polarization beam splitter (113) in the vertical incident direction is used as the output of the seed pulse source module; The pulse width broadening module (2) has the following optical path structure. The optical pulse is transmitted to the first grating (202) through the first reflector (201). After the first grating (202) transmits the optical pulse to the second reflector (203), it is reflected to the third reflector (204). The third reflector (204) reflects the optical pulse back to the first grating (202). The pulse output by the first grating (202) is transmitted to the fourth reflector (206) through the first convex lens (205) and then reflected back to the first grating (202) through the first convex lens (205). The optical pulse is transmitted to the second reflector (203) through the first grating (202). The second reflector (203) reflects the optical pulse and after being reflected by the third reflector (204), it is incident on the first grating (202). The optical pulse output by the first grating (202) is incident on the Porro prism (207) and is reflected back to the first grating (202) by the Porro prism (207). The optical pulse is transmitted to the second reflector (203) after passing through the first grating (202), and then reflected to the third reflector (204). The third reflector (204) reflects the optical pulse back to the first grating (202). After being output by the first grating (202), it is transmitted to the fourth reflector (206) through the first convex lens (205). After being reflected by the fourth reflector (206), it is transmitted to the first grating (202) through the first convex lens (205) again. It is transmitted to the second reflector (203) through the first grating (202), and then reflected to the third reflector (204). The third reflector (204) reflects the optical pulse back to the first grating (202). It is transmitted to the Porro prism (207) through the first grating (202) and is reflected back to the first grating (202) by the Porro prism (207), and finally is output by the first grating (202). The pulse pickup module (3) has the following optical path structure. The optical pulse is incident on the second convex lens (301). The optical pulse passes through the second convex lens (301), acousto-optic modulator (302), third convex lens (303), third isolator (304), and second half-wave plate (305) and then is incident on the fifth mirror (306). The optical pulse is reflected by the fifth mirror (306) to the sixth mirror (307) and then is incident on the fourth convex lens (308). The optical pulse passes through the fourth convex lens (308), third collimator (309), second erbium-doped fiber (310), fourth collimator (311), and fifth convex lens (312) and then is incident on the seventh mirror (313). The pump light generated by the first photodiode (316) passes through the fifth collimator (315) and sixth convex lens (314) and then is fused with the optical pulse incident on the seventh mirror (313) via the fourth collimator (311) and fifth convex lens (312). The fused optical pulse is reflected by the seventh mirror (313) to the eighth mirror (317). The eighth mirror (317) reflects the optical pulse to the third half-wave plate (318). The optical pulse passes through the third half-wave plate (318), third quarter-wave plate (319), band-pass filter (320), and fourth half-wave plate (321) and then is incident on the second grating (325). The optical pulse is transmitted by the second grating (325) to the third grating (326). The third grating (326) transmits the optical pulse to the ninth mirror (327). The ninth mirror (327) reflects the pulse back to the third grating (326). The optical pulse is transmitted by the third grating (326) to the second grating (325). The optical pulse output by the second grating (325) is transmitted to the tenth mirror (322) and is reflected by the tenth mirror (322) into the fifth half-wave plate (323), and finally is output through the second polarization beam splitter (324). The partial pulse time-domain splitting module (4) has the following optical path structure. The optical pulse is incident on the input end of the third polarization beam splitter (402) through the sixth half-wave plate (401). The optical pulse is output from the output end of the third polarization beam splitter (402) in the direction perpendicular to the incident direction and is transmitted through the fourth quarter-wave plate (403) to the eleventh mirror (404). The eleventh mirror (404) reflects the optical pulse back to the fourth quarter-wave plate (403), and the fourth quarter-wave plate (403) transmits the optical pulse to the third polarization beam splitter (402) again. At the same time, the optical pulse is output from another output end of the third polarization beam splitter (402) perpendicular to the incident direction and is transmitted through the fifth quarter-wave plate (405) to the twelfth mirror (406) and the first piezoelectric actuator (407). Then, the optical pulse is reflected back to the fifth quarter-wave plate (405) by the twelfth mirror (406), and the fifth quarter-wave plate (405) transmits the optical pulse back to the third polarization beam splitter (402). The optical pulse is output from the port of the third polarization beam splitter (402) parallel to the incident direction and is transmitted through the seventh half-wave plate (408) to the fourth polarization beam splitter (409). The optical pulse is transmitted through the sixth quarter-wave plate (410) from the port of the fourth polarization beam splitter (409) perpendicular to the incident direction to the thirteenth mirror (411). The thirteenth mirror (411) reflects the optical pulse back to the sixth quarter-wave plate (410), and the sixth quarter-wave plate (410) transmits the optical pulse back to the fourth polarization beam splitter (409) again. At the same time, the optical pulse is transmitted through the seventh quarter-wave plate (412) from another port of the fourth polarization beam splitter (409) perpendicular to the incident direction to the fourteenth mirror (413) and the second piezoelectric actuator (414). Then, the optical pulse is reflected back to the seventh quarter-wave plate (412) by the fourteenth mirror (413), and the seventh quarter-wave plate (412) transmits the optical pulse to the fourth polarization beam splitter (409) again. The optical pulse is output from the output end of the fourth polarization beam splitter (409) parallel to the incident direction; The first-stage pulse-width compression module (5) has the following optical path structure. The optical pulse is transmitted to the fourth grating (5001), and after being reflected by the fourth grating (5001), it reaches the concave mirror (5002). The concave mirror (5002) reflects the optical pulse to the fifteenth mirror (5003). After the optical pulse is reflected by the fifteenth mirror (5003) and reaches the concave mirror (5002), it is transmitted by the concave mirror (5002) to the fourth grating (5001). After passing through the fourth grating (5001), the optical pulse is transmitted again along the above-mentioned route through the concave mirror (5002) and the fifteenth mirror (5003). After multiple reflections, the optical pulse returns to the fourth grating (5001). The fourth grating (5001) reflects the optical pulse to the sixteenth mirror (5004). The optical pulse is transmitted by the sixteenth mirror (5004) to the seventeenth mirror (5005), then transmitted by the seventeenth mirror (5005) to the eighteenth mirror (5006), and then transmitted by the eighteenth mirror (5006) to the nineteenth mirror (5007). After that, the optical pulse undergoes spectral shaping through seven mirrors in sequence: the optical pulse passes through the twentieth mirror (5008), the twenty-first mirror (5009), the twenty-second mirror (5010), the twenty-third mirror (5011), the twenty-fourth mirror (5012), the twenty-fifth mirror (5013), and the twenty-sixth mirror (5014) in sequence and then is incident on the twenty-seventh mirror (5015). The optical pulse is incident on the input end of the first beam splitter (5016) through the twenty-seventh mirror (5015), and is transmitted from the output end of the first beam splitter (5016) to the twenty-eighth mirror (5017). After being reflected by the twenty-eighth mirror (5017), the optical pulse is reflected by the twenty-ninth mirror (5018), and then reflected by the twenty-ninth mirror (5018) to the thirtieth mirror (5019). The thirtieth mirror (5019) reflects the optical pulse to the thirty-first mirror (5020). The optical pulse is reflected by the thirty-first mirror (5020) to the seventh convex lens (5021). After passing through the seventh convex lens (5021), the eighth convex lens (5022), and the first dichroic mirror (5023), the optical pulse is transmitted and output through the first dichroic mirror (5023). The optical pulse is fused with the optical pulse that is reflected by the sixty-third mirror (5107) and then reflected and output through the first dichroic mirror (5023). The fused optical pulse is transmitted by the first dichroic mirror (5023) to the first KTiAsO4 crystal (5024). The optical pulse is transmitted by the first KTiAsO4 crystal (5024) to the second dichroic mirror (5025). The short-wavelength optical pulse reflected from the second dichroic mirror (5025) is transmitted to the thirty-second mirror (5103), and the long-wavelength optical pulse transmitted through the second dichroic mirror (5025) is transmitted to the third dichroic mirror (5026). The optical pulse reflected by the third dichroic mirror (5026) is transmitted to the thirty-third mirror (5104).The light pulse transmitted from the third dichroic mirror (5026) is incident on the thirty-fourth mirror (5027). The light pulse is reflected by the thirty-fourth mirror (5027) to the thirty-fifth mirror (5028), reflected by the thirty-fifth mirror (5028) to the ninth convex lens (5029), transmitted through the ninth convex lens (5029) to the tenth convex lens (5030), and after passing through the tenth convex lens (5030), it is incident on the thirty-sixth mirror (5031). The light pulse is reflected by the thirty-sixth mirror (5031) to the thirty-seventh mirror (5032), reflected by the thirty-seventh mirror (5032) to the thirty-eighth mirror (5033), reflected by the thirty-eighth mirror (5033) to the thirty-ninth mirror (5034), transmitted through the thirty-ninth mirror (5034) to the fourth dichroic mirror (5035), transmitted through the fourth dichroic mirror (5035) to the second KTiAsO4 crystal (5036). The light pulse is transmitted through the second KTiAsO4 crystal (5036) to the fifth dichroic mirror (5037). The light pulse reflected from the fifth dichroic mirror (5037) is transmitted to the fortieth mirror (5105), and the light pulse transmitted through the fifth dichroic mirror (5037) is transmitted to the sixth dichroic mirror (5038). The light pulse reflected by the sixth dichroic mirror (5038) is transmitted to the forty-first mirror (5106). The light pulse transmitted and output from the sixth dichroic mirror (5038) is incident on the eleventh convex lens (5039), transmitted through the eleventh convex lens (5039) to the twelfth convex lens (5040), and incident on the fifth grating (5042) through the twelfth convex lens (5040). The fifth grating (5042) reflects the light pulse onto the sixth grating (5043), and the sixth grating (5043) reflects the light pulse onto the first roof mirror (5044). After the light pulse reaches the first roof mirror (5044), it is reflected back to the fifth grating (5042) along the input path. The fifth grating (5042) transmits the light pulse to the forty-second mirror (5041). After the light pulse is reflected by the forty-second mirror (5041) to the forty-third mirror (5045), it is reflected by the forty-third mirror (5045) to the forty-fourth mirror (5046), reflected by the forty-fourth mirror (5046) to the forty-fifth mirror (5047), reflected by the forty-fifth mirror (5047) to the forty-sixth mirror (5048), reflected by the forty-sixth mirror (5048) to the knife-edge prism (5099), and transmitted from the other output end of the first beam splitter (5016) to the forty-seventh mirror (5049). After the light pulse is reflected by the forty-seventh mirror (5049) to the forty-eighth mirror (5050), it is reflected by the forty-eighth mirror (5050) to the forty-ninth mirror (5051), reflected by the forty-ninth mirror (5051) to the fiftieth mirror (5052), reflected by the fiftieth mirror (5052) to the fifty-first mirror (5053).The optical pulse is reflected by the fifty-first mirror (5053) to the thirteenth convex lens (5054). After passing through the thirteenth convex lens (5054) and the fourteenth convex lens (5055), the optical pulse is reflected by the fourteenth convex lens (5055) to the seventh dichroic mirror (5056). After being transmitted by the seventh dichroic mirror (5056), the optical pulse is fused with the optical pulse that is incident on the seventh dichroic mirror (5056) along the sixty-eighth mirror (5108) and then reflected. The fused optical pulse is incident on the seventh dichroic mirror (5056) and then enters the third KTiAsO4 crystal (5057). The optical pulse is transmitted through the third KTiAsO4 crystal (5057) to the eighth dichroic mirror (5058). The optical pulse reflected from the eighth dichroic mirror (5058) is reflected to the fifty-second mirror (5059). The optical pulse transmitted through the eighth dichroic mirror (5058) is transmitted to the ninth dichroic mirror (5060). The optical pulse reflected by the ninth dichroic mirror (5060) is transmitted to the fifty-third mirror (5061). The optical pulse output from the ninth dichroic mirror (5060) is incident on the fifty-third mirror (5061). The optical pulse transmitted through the ninth dichroic mirror (5060) is incident on the fifty-fourth mirror (5062). After being reflected by the fifty-fourth mirror (5062), it is reflected to the fifty-fifth mirror (5063). After being reflected by the fifty-fifth mirror (5063) to the fifteenth convex lens (5064), the optical pulse passes through the fifteenth convex lens (5064) and the sixteenth convex lens (5065) and is incident on the fifty-sixth mirror (5066). The optical pulse is reflected by the fifty-sixth mirror (5066) to the fifty-seventh mirror (5067), then reflected by the fifty-seventh mirror (5067) to the fifty-eighth mirror (5068), then reflected by the fifty-eighth mirror 568 to the fifty-ninth mirror (5069), then reflected by the fifty-ninth mirror (5069) to the tenth dichroic mirror (5070), and is transmitted and output. The optical pulse is fused with the optical pulse that is reflected by the sixty-ninth mirror (5098) to the tenth dichroic mirror (5070) and then reflected and output, and is incident on the fourth KTiAsO4 crystal (5071). The optical pulse is transmitted through the fourth KTiAsO4 crystal (5071) to the eleventh dichroic mirror (5072). The optical pulse reflected from the eleventh dichroic mirror (5072) is transmitted to the sixtieth mirror (5073). The optical pulse transmitted through the eleventh dichroic mirror (5072) is transmitted to the twelfth dichroic mirror (5074). The optical pulse reflected by the twelfth dichroic mirror (5074) is transmitted to the sixty-first mirror (5075). The optical pulse transmitted through the twelfth dichroic mirror (5074) is incident on the seventeenth convex lens (5076), transmitted through the eighteenth convex lens (5076) to the eighteenth convex lens (5077), and incident on the seventh grating (5078). The seventh grating (5078) reflects the optical pulse onto the eighth grating (5079).The eighth grating (5079) reflects the optical pulse onto the second roof mirror (5080). After the optical pulse reaches the second roof mirror (5080), it is reflected back along the input path to the seventh grating (5078). The seventh grating (5078) transmits the optical pulse to the sixty-second mirror (5081). After being reflected by the sixty-second mirror (5081), the optical pulse is reflected by the sixty-third mirror (5082) to the sixty-fourth mirror (5083), then reflected by the sixty-fourth mirror (5083) to the knife-edge prism (5099). The optical pulse pumped by the laser (5084) is transmitted to the thirteenth dichroic mirror (5085). The optical pulse reflected from the thirteenth dichroic mirror (5085) passes through the eighth half-wave plate (5086) and is incident on the first thin-film polarizer (5087). The parallel polarized optical pulse transmitted through the first thin-film polarizer (5087) is incident on the sixty-fifth mirror (5107). The optical pulse is reflected by the sixty-fifth mirror (5107) to the first dichroic mirror (5023). The vertically polarized optical pulse reflected from the first thin-film polarizer (5087) is incident on the second thin-film polarizer (5088). After being reflected by the second thin-film polarizer (5088), the optical pulse passes through the ninth half-wave plate (5089) and the third erbium-doped fiber (5090) and is transmitted to the sixty-sixth mirror (5091). The optical pulse is reflected by the sixty-sixth mirror (5091) to the fourth dichroic mirror (5035). The optical pulse reflected from the fourth dichroic mirror (5035) is fused with the optical pulse that is incident on the fourth dichroic mirror (5035) through the thirty-ninth mirror (5034) and then transmitted through the fourth dichroic mirror (5035). The fused optical pulse is incident on the second KTiAsO4 crystal (5036). The optical pulse output from the thirteenth dichroic mirror (5085) is transmitted by the sixty-seventh mirror (5092) to the tenth half-wave plate (5093). The optical pulse is incident on the third thin-film polarizer (5094) through the tenth half-wave plate (5093). The parallel polarized optical pulse transmitted through the third thin-film polarizer (5094) is incident on the sixty-eighth mirror (5108). The optical pulse is reflected by the sixty-eighth mirror (5108) to the seventh dichroic mirror (5056). The vertically polarized optical pulse reflected from the third thin-film polarizer (5094) is incident on the fourth thin-film polarizer (5095). After being reflected by the fourth thin-film polarizer (4080), the optical pulse passes through the eleventh half-wave plate (5096) and the fourth erbium-doped fiber (5097) and is transmitted to the sixty-ninth mirror (5098). The optical pulse is reflected by the sixty-ninth mirror (5098) to the tenth dichroic mirror (5070). Finally, the two identical optical pulses incident on the knife-edge prism (5099) are transmitted to the seventieth mirror (5100). The optical pulse is reflected by the seventieth mirror (5100) to the seventy-first mirror (5101) and then reflected to the CaF2 lens (5102). The two optical pulses are fused by the CaF2 lens (5102) and then output; The polarization pulse coherent superposition module (6) has the following optical path structure. An optical pulse is incident on the fifth polarization beam splitter (601), and the output end of the optical pulse in the direction perpendicular to the incident direction of the fifth polarization beam splitter (601) outputs the optical pulse. The optical pulse is reflected by the seventy-second mirror (602) to the seventy-third mirror (603), reflected by the seventy-third mirror (603) to the seventy-fourth mirror (604), reflected by the seventy-fourth mirror (604) to the seventy-fifth mirror (605), and after being reflected back to the fifth polarization beam splitter (601) by the seventy-fifth mirror (605), it outputs from the output end of the fifth polarization beam splitter (601) in the parallel incident direction. After the optical pulse is output by the fifth polarization beam splitter (601), it passes through the twelfth half-wave plate (606) and is transmitted to the sixth polarization beam splitter (607). The optical pulse is transmitted to the seventy-sixth mirror (608) along the output end of the sixth polarization beam splitter (607) perpendicular to the incident direction. The optical pulse is reflected by the seventy-sixth mirror (608) to the seventy-seventh mirror (609), reflected by the seventy-seventh mirror (609) to the seventy-eighth mirror (610), reflected by the seventy-eighth mirror (610) to the seventy-ninth mirror (611), and reflected back to the sixth polarization beam splitter (607) by the seventy-ninth mirror (611). The optical pulse outputs from the other output end parallel to the incident direction of the sixth polarization beam splitter (607). The optical pulse is transmitted to the thirteenth half-wave plate (612) through the sixth polarization beam splitter and is transmitted to the seventh polarization beam splitter (613), and finally outputs from the seventh polarization beam splitter (613); The second-order pulse width compression module (7) has the following beam structure. An optical pulse is incident on the ninth grating (701). The optical pulse output from the ninth grating (701) passes through the nineteenth convex lens (702), the optical slit (703), and the twentieth convex lens (704) and then is incident on the tenth grating (705). The optical pulse output from the tenth grating (705) passes through the eighth quarter-wave plate (706) and is incident on the eightieth mirror (707). After the optical pulse reaches the eightieth mirror (707), it returns along the original path to the ninth grating (701). The optical pulse output from the ninth grating (701) passes through the thermally filled hollow-core fiber (708) and is incident on the eleventh grating (709). The optical pulse is reflected by the eleventh grating (709) to the twelfth grating (710), and then is reflected by the twelfth grating (710) to the first fused silica plate (711). The optical pulse passes through the first fused silica plate (711) and the BBO crystal (712) and then is incident on the first chirped mirror (713). The optical pulse is reflected by the first chirped mirror (713) to the second chirped mirror (714), and then is reflected back to the first chirped mirror (713) by the second chirped mirror (714). After multiple reflections between the first chirped mirror (713) and the second chirped mirror (714), the optical pulse returns to the second chirped mirror (714). The optical pulse is transmitted by the second chirped mirror (714) to the eighty-first mirror (715), is reflected by the eighty-first mirror (715) to the second fused silica plate (716), and is incident on the aluminum D-shaped split mirror (717) through the second fused silica plate (716). The optical pulse output from the D-shaped split mirror (717) is incident on the eighty-second mirror (718). The optical pulse is reflected by the eighty-second mirror (718) to the eighty-third mirror (719), and then is reflected by the eighty-third mirror (719) to the second concave mirror (720). After that, the optical pulse is transmitted by the second concave mirror (720) to the third fused silica plate (723). The optical pulse output from the other end of the D-shaped split mirror (717) is transmitted to the eighty-fourth mirror (721), is reflected by the eighty-fourth mirror (721) to the eighty-fifth mirror (722), and then is reflected by the eighty-fifth mirror (722) to the second concave mirror (720). After that, the optical pulse is transmitted by the second concave mirror (720) to the third fused silica plate (723). The residual light beam passing through the third fused silica plate (723) is incident on the beam stopper (724). The optical pulse passing through the third fused silica plate (723) is finally output by the twenty-first convex lens (725).

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