[2] [2] DI J, ZHANG J, XI T, et al. Improvement of measurement accuracy in digital holographic microscopy by using dual-wavelength technique[J]. Journal of Micro/Nanolithography, MEMS, and MOEMS, 2015, 14（4）: 041313.

[4] [4] ZHONG K, SHI W, XU D G, et al. Optically pumped terahertz sources[J]. Science China Technological Sciences, 2017, 60（12）: 1801-1818.

[5] [5] GUO L, LAN R, LIU H, et al. 1319 nm and 1338 nm dual-wavelength operation of LD end-pumped Nd: YAG ceramic laser[J]. Optics Express, 2010, 18（9）: 9098-9106.

[6] [6] CHEN L, WANG Z, ZHUANG S, et al. Dual-wavelength Nd:YAG crystal laser at 1074 and 1112 nm[J]. Optics Letters, 2011, 36（13）: 2554-2556.

[7] [7] ZHONG K, SUN C, YAO J, et al. Efficient continuous-wave 1053-nm Nd:GYSGG laser with passively Q-switched dual-wavelength operation for terahertz generation[J]. IEEE Journal of Quantum Electronics, 2013, 49（3）: 375-379.

[8] [8] SUN G, LI Y, ZHAO M, et al. A quasi-three-level dual-wavelength thin-disk laser at 1024 and 1030 nm based on a diode-pumped Yb:YAG crystal[J]. Laser Physics, 2013, 23（4）: 045003.

[9] [9] ZHANG H, CHEN X, WANG Q, et al. Continuous-wave dual-wavelength Nd:YAG ceramic laser at 1112 and 1116 nm[J]. Chinese Physics Letters, 2013, 30（10）: 104202.

[10] [10] SATO A, OKUBO S, ASAI K, et al. Stable dual-wavelength Q-switched Nd:YAG laser using a two-step energy extraction technique[J]. Applied Optics, 2015, 54（10）: 3032-3042.

[11] [11] GAO Y, ZHANG B, SONG Q, et al. Dual-wavelength passively Q-switched Nd:GYSGG laser by tungsten disulfide saturable absorber[J]. Applied Optics, 2016, 55（18）: 4929-4932.

[12] [12] LIN H, ZHU W, XIONG F, et al. Simultaneous dual-wavelength Q-switched Nd:YAG laser at 1052 and 1073 nm[J]. Applied Optics, 2017, 56（4）: 948-951.

[13] [13] LIN H, ZHU W, MU R, et al. Q-switched dual-wavelength laser at 1116 and 1123 nm using WS2 saturable absorber[J]. IEEE Photonics Technology Letters, 2017, 30（3）: 285-288.

[14] [14] HAN S, ZHOU S, LIU X, et al. Rhenium disulfide-based passively Q-switched dual-wavelength laser at 0.95 μm and 1.06 μm in Nd:YAG[J]. Laser Physics Letters, 2018, 15（8）: 085804.

[16] [16] SHANG L, WEN Y, LI T, et al. Pulse peaks synchronize dual-wavelength laser based on Q-switch delay trigger[J]. Infrared Physics&Technology, 2021, 116: 103751.

[17] [17] WANG X, WANG Z, BU Y, et al. A 1064 nm, 1085 nm dual-wavelength Nd:YVO4 laser using Fabry-Perot filters as output couplers[J]. IEEE Photonics Technology Letters, 2014, 26（19）: 1983-1985.

[18] [18] WANG X, WANG Z, BU Y, et al. A 1064-nm and 1074-nm dual-wavelength Nd:YAG laser using a Fabry-Perot band-pass filter as output mirror[J]. IEEE Photonics Journal, 2014, 6（4）: 1-6.

[19] [19] WANG X, YUAN H, WANG M, et al. Continuous 1052, 1064 nm dual-wavelength Nd:YAG laser[J]. Optics Communications, 2016, 376: 67-71.

[20] [20] LIU L, DAI C, WANG X. A continuous 1052 nm and 1061 nm dual-wavelength Nd:YAG laser[J]. Optoelectronics Letters, 2020, 16（3）: 181-184.

[21] [21] LI C, BO Y, XU J, et al. Simultaneous dual-wavelength oscillation at 1116 and 1123 nm of Nd:YAG laser[J]. Optics Communications, 2011, 284（19）: 4574-4576.

[22] [22] HUANG Y, CHO C, HUANG Y, et al. Orthogonally polarized dual-wavelength Nd:LuVO4 laser at 1086 nm and 1089 nm[J]. Optics Express, 2012, 20（5）: 5644-5651.

[23] [23] ZHANG X, ZHANG S, WANG C, et al. Orthogonally polarized dual-wavelength single-longitudinal-mode Tm, Ho:LLF laser[J]. Optics Express, 2013, 21（19）: 22699-22704.

[24] [24] Lü Y, XIA J, ZHANG J, et al. Orthogonally polarized dual-wavelength Nd:YAlO3 laser at 1341 and 1339 nm and sum-frequency mixing for an emission at 670 nm[J]. Applied Optics, 2014, 53（23）: 5141-5146.

[25] [25] XIA J, Lü Y, LIU H, et al. Diode-pumped Pr3+:LiYF4 visible dual-wavelength laser[J]. Optics Communications, 2015, 334: 160-163.

[26] [26] ZHANG J, LIU H, XIA J, et al. Orthogonally polarized dual-wavelength Nd:YLiF4 laser[J]. Chinese Optics Letters, 2015, 13（3）: 031402.

[27] [27] LIN Z, HUANG X, LAN J, et al. Efficient and compact diode-pumped Nd:YAG lasers at 1073 and 1078 nm[J]. IEEE Photonics Journal, 2016, 8（2）: 1-8.

[28] [28] XU B, WANG Y, LIN Z, et al. Efficient and compact orthogonally polarized dual-wavelength Nd:YVO4 laser at 1342 and 1345 nm[J]. Applied Optics, 2016, 55（1）: 42-46.

[29] [29] ZUO Z, DAI S, ZHU S, et al. Power scaling of an actively Q-switched orthogonally polarized dual-wavelength Nd:YLF laser at 1047 and 1053 nm[J]. Optics Letters, 2018, 43（19）: 4578-4581.

[30] [30] TREVINO-PALACIOS C, ZAPATAa-NAVA O, MEJIA-URIARTE E, et al. Dual wavelength continuous wave laser using a birefringent filter[J]. Journal of the European Optical Society-Rapid Publications, 2013, 8: 13021.

[31] [31] AKBARI R, ZHAO H, MAJOR A. High-power continuous-wave dual-wavelength operation of a diode-pumped Yb:KGW laser[J]. Optics Letters, 2016, 41（7）: 1601-1604.

[32] [32] GHANBARI S, MAJOR A. High power continuous-wave dual-wavelength alexandrite laser[J]. Laser Physics Letters, 2017, 14（10）: 105001.

[33] [33] DEMIRBAS U, UECKER R, FUJIMOTO J G, et al. Multicolor lasers using birefringent filters: experimental demonstration with Cr:Nd:GSGG and Cr:LiSAF[J]. Optics Express, 2017, 25（3）: 2594-2607.

[34] [34] WARITANANT T, MAJOR A. Dual-wavelength operation of a diode-pumped Nd:YVO4 laser at the 1064.1&1073.1 nm and 1064.1&1085.3 nm wavelength pairs[J]. Applied Physics B, 2018, 124（5）: 1-7.

[35] [35] HE J, WEI F, LIU H, et al. Tunable continuous-wave dual-wavelength laser operation of Pr3+:LiYF4 around 900 nm[J]. Laser Physics Letters, 2021, 18（8）: 085003.

[36] [36] BRENIER A. Two-frequency pulsed YLiF4: Nd lasing out of the principal axes and THz generation[J]. Optics Letters, 2015, 40（19）: 4496-4499.

[37] [37] JIA F, CHEN H, LIU P, et al. Nanosecond-pulsed, dual-wavelength passively Q-switched c-cut Nd:YVO4 laser using a few-layer Bi2Se3 saturable absorber[J]. IEEE Journal of Selected Topics in Quantum Electronics, 2014, 21（1）: 369-374.

[38] [38] SMIRNOV I, ZVEREV P, SIROTKIN A. Efficient multiwavelength operation of a diode-pumped Nd:YAlO3 laser at 1064, 1072 and 1079 nm[J]. Laser Physics Letters, 2020, 17（9）: 095001.

[39] [39] GAO C, LV S, ZHU G, et al. Self-Q-switching and passively Q-switched mode-locking of dual-wavelength Nd:YSAG laser[J]. Optics&Laser Technology, 2020, 122: 105860.

[40] [40] YU H, ZHANG H, WANG Z, et al. High-power dual-wavelength laser with disordered Nd:CNGG crystals[J]. Optics Letters, 2009, 34（2）: 151-153.

[41] [41] ZHONG K, YAO J, SUN C, et al. Efficient diode-end-pumped dual-wavelength Nd,Gd:YSGG laser[J]. Optics Letters, 2011, 36（19）: 3813-3815.

[42] [42] SONG Q, WANG G, ZHANG B, et al. Diode-pumped passively dual-wavelength Q-switched Nd:GYSGG laser using graphene oxide as the saturable absorber[J]. Applied Optics, 2015, 54（10）: 2688-2692.

[43] [43] WANG X, XU J, GAO S, et al. Dual-wavelength passively Q-switched bulk laser using MoS2/graphene heterojunction[J]. Materials Research Bulletin, 2017, 89: 63-67.

[44] [44] WU B, JIANG P, YANG D, et al. Compact dual-wavelength Nd:GdVO4 laser working at 1063 and 1065 nm[J]. Optics Express, 2009, 17（8）: 6004-6009.

[45] [45] Lü Y, ZHAI P, XIA J, et al. Simultaneous orthogonal polarized dual-wavelength continuous-wave laser operation at 1079.5 nm and 1064.5 nm in Nd:YAlO3 and their sum-frequency mixing[J]. JOSA B, 2012, 29（9）: 2352-2356.

[46] [46] HONG K, WEI M. Simultaneous dual-wavelength pulses achieved by mixing spiking and passive Q-switching in a pulsed Nd:GdVO4 laser with a Cr4+:YAG saturable absorber[J]. Optics Letters, 2016, 41（10）: 2153-2156.

[47] [47] HONG K, LU Y, WEI M. Dual-wavelength pulsed dynamics in Nd:GdVO4 laser with Cr4+:YAG saturable absorber: roles of pump rate and spot size[J]. JOSA B, 2017, 34（8）: 1740-1746.

[48] [48] PALLAS F, HERAULT E, ZHOU J, et al. Stable dual-wavelength microlaser controlled by the output mirror tilt angle[J]. Applied Physics Letters, 2011, 99（24）: 241113.

[49] [49] CHU H, ZHAO S, LI T, et al. Dual-wavelength passively Q-switched Nd, Mg:LiTaO3 laser with a monolayer graphene as saturable absorber[J]. IEEE Journal of Selected Topics in Quantum Electronics, 2014, 21（1）: 343-347.

[50] [50] CHEN H, HUANG Y, LI B, et al. Efficient orthogonally polarized dual-wavelength Nd: LaMgB5O10 laser[J]. Optics Letters, 2015, 40（20）: 4659-4662.

[51] [51] SUN S, WEI Q, LI B, et al. The YMgB5O10 crystal preparation and attractive multi-wavelength emission characteristics of doping Nd3+ ions[J]. Journal of Materials Chemistry C, 2021, 9（6）: 1945-1957.

[52] [52] TU Z, DAI S, ZHU S, et al. Efficient high-power orthogonally-polarized dual-wavelength Nd:YLF laser at 1314 and 1321 nm[J]. Optics Express, 2019, 27（23）: 32949-32957.

[53] [53] SINGH A, SHARMA S K, GUPTA P K, et al. Studies on simultaneous dual wavelength operation at 912.2 nm and 914 nm from dual gain diode-pumped Nd3+ doped vanadate laser[J]. Optics&Laser Technology, 2014, 64: 257-263.

[54] [54] ZHANG Y, HU M, XU M, et al. Experimental investigation on the Y-type cavity tunable dual-wavelength laser based on neodymium-doped vanadate crystals[J]. Optics Communications, 2021, 495: 127089.

[55] [55] SINGH A, SHARMA S, MUKHOPADHYAY P, et al. Dual wavelength operation in diode-end-pumped hybrid vanadate laser[J]. Pramana, 2010, 75（5）: 929-934.

[56] [56] HUANG Y, CHO H, CHEN Y. Observation of repetition rate locking in an orthogonally-polarized dual-wavelength passively Q-switched hybrid Nd:YVO4/Nd:YLF laser[C]//Proceedings of the CLEO: Science and Innovations, Optical Society of America, 2016: SM3M-6.

[57] [57] JIA F, LIU P, LI K, et al. Comparative study of passively Q-switched c-cut Nd:YVO4/Nd:YAG lasers based on CVD graphene and controlled operation[J]. Optics Communications, 2017, 395: 102-110.

[58] [58] HU M, KE Y, LI Q, et al. Tunable dual-wavelength laser based on Nd:YVO4/Nd:GdVO4 combined crystal[J]. Optics Express, 2019, 27（10）: 13773-13780.

[59] [59] CHEN M, DAI S, TU Z, et al. Frequency expansion of efficient passively Q-switched orthogonally-polarized dual-wavelength laser[J]. Optics&Laser Technology, 2020, 122: 105846.

[62] [62] SINGH S P, MONDAL S, HUSSAIN K, et al. Development of optical parametric oscillator tunable in the range 970-1460 nm[J]. Defence Science Journal, 2011, 61（4）: 377.

[63] [63] MEI J, ZHONG K, WANG M, et al. Widely-tunable high-repetition-rate terahertz generation in GaSe with a compact dual-wavelength KTP OPO around 2 μm[J]. Optics Express, 2016, 24（20）: 23368-23375.

[64] [64] SIROTKIN A A, YUDIN N N, DYOMIN V V, et al. Tunable THz-radiation in a ZnGeP2 single crystal pumped by dua-wavelength degenerate optical parametric oscillator[J]. Laser Physics Letters, 2020, 17（3）: 035402.

[65] [65] MENG X, WANG Z, TIAN W, et al. Tunable, high-repetition-rate, dual-signal-wavelength femtosecond optical parametric oscillator based on BiB3O6[J]. Applied Physics B, 2018, 124（1）: 1-6.

[66] [66] ZHONG K, GUO S, WANG M, et al. A non-critically phase matched KTA optical parametric oscillator intracavity pumped by an actively Q-switched Nd:GYSGG laser with dual signal wavelengths[J]. Optics Communications, 2015, 344: 17-20.

[67] [67] WANG M, ZHONG K, MEI J, et al. Simultaneous dual-wavelength eye-safe KTP OPO intracavity pumped by a Nd:GYSGG laser[J]. Journal of Physics D: Applied Physics, 2015, 49（6）: 065101.

[68] [68] YANG J, LIU S, HE J, et al. Tunable simultaneous dual-wavelength laser at 1.9 and 1.7 μm based on KTiOAsO4 optical parametric oscillator[J]. Laser Physics Letters, 2011, 8（1）: 28-31.

[69] [69] WANG P, SHANG Y, LI X, et al. A fiber laser pumped dual-wavelength mid-infrared laser based on optical parametric oscillation and intracavity difference frequency generation[J]. Laser Physics Letters, 2017, 14（2）: 025401.

[70] [70] WANG P, CHENG X, LI X, et al. Fiber-laser-pumped, continuous-wave, dual-wavelength, mid-infrared optical parametric oscillator[J]. Laser Physics, 2018, 28（8）: 085103.

[71] [71] WANG P, CHENG X, LI X, et al. Tunable dual-wavelength, continuous-wave, mid-infrared generation using intracavity difference frequency mixing in PPLN-based optical parametric oscillator[J]. IEEE Journal of Selected Topics in Quantum Electronics, 2018, 24（5）: 1-7.

[72] [72] CHENG X, WANG P, LI X, et al. Low threshold, dual-wavelength, mid-infrared optical parametric oscillator[J]. IEEE Photonics Journal, 2018, 11（1）: 1-7.

[73] [73] FENG J, WANG P, CHENG X, et al. A high efficient dual-wavelength mid-infrared optical parametric oscillator pumped by the Raman fiber oscillator[J]. IEEE Photonics Journal, 2020, 12（3）: 1-8.

[74] [74] HUANG H, HE J, LIU S, et al. Synchronized generation of 1534 and 1572 nm by the mixed optical parameter oscillation[J]. Laser Physics Letters, 2011, 8（5）: 358.

[75] [75] YAN D, WANG Y, XU D, et al. High power, widely tunable dual-wavelength 2 μm laser based on intracavity KTP optical parametric oscillator[J]. Journal of Physics D: Applied Physics, 2016, 50（3）: 035104.

[76] [76] HUANG H, WANG S, LIU X, et al. Simultaneous dual-wavelength nanosecond mid-infrared optical parametric oscillator[J]. Infrared Physics&Technology, 2018, 93: 91-95.

[77] [77] BI G, FAN J, CHU Y, et al. Orthogonally polarized tunable dual-wavelength femtosecond optical parametric oscillator[J]. Applied Optics, 2020, 59（34）: 10887-10891.

[78] [78] ROBERTS D B, KRUSE R J, STOLL S F. The effectiveness of therapeutic class IV （10 W） laser treatment for epicondylitis[J]. Lasers in Surgery and Medicine, 2013, 45（5）: 311-317.

[79] [79] CHEN Y. CW dual-wavelength operation of a diode-end- pumped Nd:YVO4 laser[J]. Applied Physics B, 2000, 70（4）: 475-478.

[80] [80] WANG X, WANG Z, BU Y, et al. Power-ratio tunable dual-wavelength laser using linearly variable Fabry-Perot filter as output coupler[J]. Applied Optics, 2016, 55（4）: 879-883.

[81] [81] HSU C, WU S, CHOU C, et al. Continuous-wave simultaneous dual-wavelength and power-ratio-tunable operation at 1064 and 1342 nm in an Nd:LuVO4 laser[J]. Laser Physics, 2011, 21（11）: 1871-1875.

[82] [82] WARITANANT T, MAJOR A. dual-wavelength CW operations at 1064.1&1073.1 nm and 1064.1&1085.3 nm of Nd:YVO4 Laser[C]//Proceedings of the CLEO: QELS-Fundamental Science, Optical Society of America, 2014: JW2A-82.

[83] [83] QI Y, YU H, ZHANG J, et al. A compact dual-wavelength Nd:LuVO4 laser with adjustable power-ratio between 1064 nm and 1342 nm lines by controlling polarization dependent loss[J]. Optics Communications, 2017, 382: 302-306.

[84] [84] WANG C, WEN Y, WANG Y, et al. 1064/1342 nm dual-wavelength double electro-optical Q-switched Nd:YVO4 laser[J]. Optics Communications, 2021, 479: 126404.

[85] [85] HUANG Y, ZENG T Y, TANG C, et al. Efficient high-power terahertz beating in a dual-wavelength synchronously mode-locked laser with dual gain media[J]. Optics Letters, 2014, 39（6）: 1477-1480.

[86] [86] HUANG Y, CHO H, SU K, et al. Dual-Wavelength intracavity OPO with a diffusion-bonded Nd:YVO4/Nd:GdVO4 crystal[J]. IEEE Photonics Technology Letters, 2016, 28（10）: 1123-1126.

[87] [87] LIU Y, ZHONG K, MEI J, et al. Compact and flexible dual-wavelength laser generation in coaxial diode-end-pum- ped configuration[J]. IEEE Photonics Journal, 2016, 9（1）: 1-10.

[88] [88] LIU Y, ZHONG K, MEI J, et al. Compact and stable high-repetition-rate terahertz generation based on an efficient coaxially pumped dual-wavelength laser[J]. Optics Express, 2017, 25（25）: 31988-31996.

[89] [89] LIU Y, ZHONG K, SHI J, et al. Dual-signal-resonant optical parametric oscillator intracavity driven by a coaxially end-pumped laser with compound gain media[J]. Optics Express, 2018, 26（16）: 20768-20776.

[90] [90] LIU Y, SHENG Q, ZHONG K, et al. Dual-wavelength intracavity Raman laser driven by a coaxially pumped dual-crystal fundamental laser[J]. Optics Express, 2019, 27（20）: 27797-27806.

[91] [91] LIU Y, ZHONG K, SHENG Q, et al. Multiple and selectable wavelength green laser generation based on coaxial diode-end-pumping[C]//Proceedings of the Solid State Lasers XXIX: Technology and Devices, International Society for Optics and Photonics, 2020: 1125910.

[92] [92] MOHAMED M, ZHANG B, MA Q, et al. Efficient dual-wavelengths continuous mode lasers by end-pumping of series Nd:YVO4 and Nd:GdVO4 crystals and speckle reduction study[J]. Photonics, 2019, 6（2）: 53.

[93] [93] ZHONG K, LIU C, LIU Y, et al. Power-ratio tunable dual-band Nd:GYSGG laser at 0.94 μm and 1.06 μm[J]. Laser Physics, 2017, 27（12）: 125804.

[94] [94] NADIMI M, ONYENEKWU C, MAJOR A. Continuous-wave dual-wavelength operation of the in-band diode-pumped Nd:GdVO4/Nd:YVO4 composite laser with controllable spectral power ratio[J]. Applied Physics B, 2020, 126（5）: 1-5.

[95] [95] WU Q, GAO Z, WU Z, et al. Generation of a simultaneous orthogonally polarized dual-wavelength Raman laser with power ratio tunability by a single hexagonal crystal: Cs2TeMo3O12[J]. Optics Letters, 2020, 45（18）: 5061-5064.

[96] [96] ZHAO X, ZHENG Z, LIU L, et al. Fast, long-scan-range pump-probe measurement based on asynchronous sampling using a dual-wavelength mode-locked fiber laser[J]. Optics Express, 2012, 20（23）: 25584-25589.

[97] [97] SANTIAGO J G, WERELEY S T, MEINHART C D, et al. A particle image velocimetry system for microfluidics[J]. Experiments in Fluids, 1998, 25（4）: 316-319.

[98] [98] DING Y J. Progress in terahertz sources based on difference-frequency generation[J]. JOSA B, 2014, 31（11）: 2696-2711.

[99] [99] CHENG H P H, TIDEMAND-LICHTENBERG P, JENSEN O B, et al. All passive synchronized Q-switching of a quasi-three-level and a four-level Nd:YAG laser[J]. Optics Express, 2010, 18（23）: 23987-23993.

[100] [100] Majki? A, ZGONIK M, PETELIN A, et al. Terahertz source at 9.4 THz based on a dual-wavelength infrared laser and quasi-phase matching in organic crystals OH1[J]. Applied Physics Letters, 2014, 105（14）: 141115.

[101] [101] STAUFERT D, CUDNEY R S. Synchronization of pairs of nanosecond pulses from a laser with two gain crystals pumped with two different sources[J]. Applied Optics, 2018, 57（14）: 3947-3952.

[102] [102] ZHAO P, RAGAM S, DING Y J, et al. Power scalability and frequency agility of compact terahertz source based on frequency mixing from solid-state lasers[J]. Applied Physics Letters, 2011, 98（13）: 131106.

[103] [103] ZHAO P, DING Y J, ZOTOVA I B. Synchronized dual-frequency pulses from Q-switched compact Nd:YLF laser cavities[C]//Proceedings of the CLEO/QELS: 2010 Laser Science to Photonic Applications, IEEE, 2010:1-2.

[104] [104] ZHAO P, RAGAM S, DING Y J, et al. Compact and portable terahertz source by mixing two frequencies generated simultaneously by a single solid-state laser[J]. Optics Letters, 2010, 35（23）: 3979-3981.

[105] [105] MEN S, LIU Z, CONG Z, et al. Synchronized dual tunable wavelength Q-switched Nd:Glass laser[J]. Optics Express, 2014, 22（25）: 30865-30872.

[106] [106] ZHANG Xianzhong, ZHONG Kai, QIAO Hongzhan, et al. Passively Q-switched dual-wavelength laser operation with coaxially end-pumped composite laser materials[J]. IEEE Photonics Journal, 2021, 13（6）: 1-7.