Tunable and switchable harmonic h-shaped pulse generation in a 3.03 km ultralong mode-locked thulium-doped fiber laser
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摘要
We experimentally demonstrated a type of tunable and switchable harmonic h-shaped pulse generation in a thulium-doped fiber(TDF) laser passively mode locked by using an ultralong nonlinear optical loop mirror.The total cavity length was ～3.03 km, the longest ever built for a TDF laser to our best knowledge, which resulted in an ultralarge anomalous dispersion over -200 ps~2 around the emission wavelength. The produced h-shaped pulse can operate either in a fundamental or in a high-order harmonic mode-locking(HML) state depending on pump power and intra-cavity polarization state(PS). The pulse duration, no matter of the operation state, was tunable with pump power. However, pulse breaking and self-organizing occurred, resulting in high-order HML,when the pump power increased above a threshold. At a fixed pump power, the order of HML was switchable from one to another by manipulating the PS. Switching from the 8 th up to the 48 th order of HML was achieved with a fixed pump power of ～4.15 W. Our results revealed the detailed evolution and switching characteristics of the HML and individual pulse envelope with respect to both the pump power and PS. We have also discussed in detail the mechanisms of both the h-shaped pulse generation and the switching of its HML. This contribution would be helpful for further in-depth study on the underlying dynamics of long-duration particular-envelope pulses with ultralarge anomalous dispersion and ultralong roundtrip time.
We experimentally demonstrated a type of tunable and switchable harmonic h-shaped pulse generation in a thulium-doped fiber(TDF) laser passively mode locked by using an ultralong nonlinear optical loop mirror.The total cavity length was ～3.03 km, the longest ever built for a TDF laser to our best knowledge, which resulted in an ultralarge anomalous dispersion over -200 ps~2 around the emission wavelength. The produced h-shaped pulse can operate either in a fundamental or in a high-order harmonic mode-locking(HML) state depending on pump power and intra-cavity polarization state(PS). The pulse duration, no matter of the operation state, was tunable with pump power. However, pulse breaking and self-organizing occurred, resulting in high-order HML,when the pump power increased above a threshold. At a fixed pump power, the order of HML was switchable from one to another by manipulating the PS. Switching from the 8 th up to the 48 th order of HML was achieved with a fixed pump power of ～4.15 W. Our results revealed the detailed evolution and switching characteristics of the HML and individual pulse envelope with respect to both the pump power and PS. We have also discussed in detail the mechanisms of both the h-shaped pulse generation and the switching of its HML. This contribution would be helpful for further in-depth study on the underlying dynamics of long-duration particular-envelope pulses with ultralarge anomalous dispersion and ultralong roundtrip time.
We experimentally demonstrated a type of tunable and switchable harmonic h-shaped pulse generation in a thulium-doped fiber(TDF) laser passively mode locked by using an ultralong nonlinear optical loop mirror.The total cavity length was ～3.03 km, the longest ever built for a TDF laser to our best knowledge, which resulted in an ultralarge anomalous dispersion over -200 ps~2 around the emission wavelength. The produced h-shaped pulse can operate either in a fundamental or in a high-order harmonic mode-locking(HML) state depending on pump power and intra-cavity polarization state(PS). The pulse duration, no matter of the operation state, was tunable with pump power. However, pulse breaking and self-organizing occurred, resulting in high-order HML,when the pump power increased above a threshold. At a fixed pump power, the order of HML was switchable from one to another by manipulating the PS. Switching from the 8 th up to the 48 th order of HML was achieved with a fixed pump power of ～4.15 W. Our results revealed the detailed evolution and switching characteristics of the HML and individual pulse envelope with respect to both the pump power and PS. We have also discussed in detail the mechanisms of both the h-shaped pulse generation and the switching of its HML. This contribution would be helpful for further in-depth study on the underlying dynamics of long-duration particular-envelope pulses with ultralarge anomalous dispersion and ultralong roundtrip time.
引文
1.Q.Bao,H.Zhang,Y.Wang,Z.Ni,Y.Yan,Z.X.Shen,K.P.Loh,and D.Y.Tang,“Atomic-layer graphene as a saturable absorber for ultrafast pulsed lasers,”Adv.Funct.Mater.19,3077-3083(2009).
2.H.Zhang,Q.Bao,D.Tang,L.Zhao,and K.Loh,“Large energy soliton erbium-doped fiber laser with a graphene-polymer composite mode locker,”Appl.Phys.Lett.95,141103(2009).
3.H.Zhang,D.Y.Tang,L.M.Zhao,Q.L.Bao,and K.P.Loh,“Large energy mode locking of an erbium-doped fiber laser with atomic layer graphene,”Opt.Express 17,17630-17635(2009).
4.Z.Sun,T.Hasan,F.Torrisi,D.Popa,G.Privitera,F.Wang,F.Bonaccorso,D.M.Basko,and A.C.Ferrari,“Graphene mode-locked ultrafast laser,”ACS Nano 4,803-810(2010).
5.Z.Sun,D.Popa,T.Hasan,F.Torrisi,F.Wang,E.J.R.Kelleher,J.C.Travers,V.Nicolosi,and A.C.Ferrari,“A stable,wideband tunable,near transform-limited,graphene-mode-locked,ultrafast laser,”Nano Res.3,653-660(2010).
6.C.Zhao,Y.Zou,Y.Chen,Z.Wang,S.Lu,H.Zhang,S.Wen,and D.Tang,“Wavelength-tunable picosecond soliton fiber laser with topological insulator:Bi2Se3as a mode locker,”Opt.Express 20,27888-27895(2012).
7.Y.Chen,M.Wu,P.Tang,S.Chen,J.Du,G.Jiang,Y.Li,C.Zhao,H.Zhang,and S.Wen,“The formation of various multi-soliton patterns and noise-like pulse in a fiber laser passively mode-locked by a topological insulator based saturable absorber,”Laser Phys.Lett.11,055101(2014).
8.P.Yan,R.Lin,H.Chen,H.Zhang,A.Liu,H.Yang,and S.Ruan,“Topological insulator solution filled in photonic crystal fiber for passive mode-locked fiber laser,”IEEE Photon.Technol.Lett.27,264-267(2015).
9.Y.Chen,G.Jiang,S.Chen,Z.Guo,X.Yu,C.Zhao,H.Zhang,Q.Bao,S.Wen,D.Tang,and D.Fan,“Mechanically exfoliated black phosphorus as a new saturable absorber for both Q-switching and modelocking laser operation,”Opt.Express 23,12823-12833(2015).
10.Z.Luo,M.Liu,Z.Guo,X.Jiang,A.Luo,C.Zhao,X.Yu,W.Xu,and H.Zhang,“Microfiber-based few-layer black phosphorus saturable absorber for ultra-fast fiber laser,”Opt.Express 23,20030-20039(2015).
11.Y.Song,S.Chen,Q.Zhang,L.Li,L.Zhao,H.Zhang,and D.Tang,“Vector soliton fiber laser passively mode locked by few layer black phosphorus-based optical saturable absorber,”Opt.Express 24,25933-25942(2016).
12.Z.Wang,Y.Xu,S.C.Dhanabalan,J.Sophia,C.Zhao,C.Xu,Y.Xiang,J.Li,and H.Zhang,“Black phosphorus quantum dots as an efficient saturable absorber for bound soliton operation in an erbium doped fiber laser,”IEEE Photon.J.8,1503310(2016).
13.X.Jiang,S.Liu,W.Liang,S.Luo,Z.He,Y.Ge,H.Wang,R.Cao,F.Zhang,Q.Wen,J.Li,Q.Bao,D.Fan,and H.Zhang,“Broadband nonlinear photonics in few-layer MXene Ti3C2Tx(T=F,O,or OH),”Laser Photon.Rev.12,1700229(2018).
14.S.Chouli and P.Grelu,“Rains of solitons in a fiber laser,”Opt.Express17,11776-11781(2009).
15.X.Liu,X.Yao,and Y.Cui,“Real-time observation of the buildup of soliton molecules,”Phys.Rev.Lett.121,023905(2018).
16.H.Zhang,D.Y.Tang,L.M.Zhao,and X.Wu,“Dark pulse emission of a fiber laser,”Phys.Rev.A 80,045803(2009).
17.W.Chang,A.Ankiewicz,J.M.Soto-Crespo,and N.Akhmediev,“Dissipative soliton resonances,”Phys.Rev.A 78,023830(2008).
18.X.Wu,D.Y.Tang,H.Zhang,and L.M.Zhao,“Dissipative soliton resonance in an all-normal-dispersion erbium-doped fiber laser,”Opt.Express 17,5580-5584(2009).
19.C.Mou,R.Arif,A.Rozhin,and S.Turitsyn,“Passively harmonic mode locked erbium doped fiber soliton laser with carbon nanotubes based saturable absorber,”Opt.Mater.Express 2,884-890(2012).
20.J.Du,S.M.Zhang,H.F.Li,Y.C.Meng,X.L.Li,and Y.P.Hao,“L-band passively harmonic mode-locked fiber laser based on a graphene saturable absorber,”Laser Phys.Lett.9,896-900(2012).
21.Z.Luo,M.Liu,H.Liu,X.Zheng,A.Luo,C.Zhao,H.Zhang,S.Wen,and W.Xu,“2 GHz passively harmonic mode-locked fiber laser by a microfiber-based topological insulator saturable absorber,”Opt.Lett.38,5212-5215(2013).
22.M.Liu,A.Luo,W.Xu,and Z.Luo,“Coexistence of bound soliton and harmonic mode-locking soliton in an ultrafast fiber laser based on MoS2-deposited microfiber photonic device,”Chin.Opt.Lett.16,020008(2018).
23.Y.Wang,D.Mao,X.Gan,L.Han,C.Ma,T.Xi,Y.Zhang,W.Shang,S.Hua,and J.Zhao,“Harmonic mode locking of bound-state solitons fiber laser based on MoS2saturable absorber,”Opt.Express 23,205-210(2015).
24.B.Zhao,D.Y.Tang,P.Shum,W.S.Man,H.Y.Tam,Y.D.Gong,and C.Lu,“Passive harmonic mode locking of twin-pulse solitons in an erbium-doped fiber ring laser,”Opt.Commun.229,363-370(2004).
25.L.M.Zhao,D.Y.Tang,T.H.Cheng,C.Lu,H.Y.Tam,X.Q.Fu,and S.C.Wen,“Passive harmonic mode locking of soliton bunches in a fiber ring laser,”Opt.Quantum Electron.40,1053-1064(2008).
26.L.M.Zhao,D.Y.Tang,T.H.Cheng,H.Y.Tam,and C.Lu,“Passive harmonic mode locking of gain-guided solitons in erbium-doped fiber lasers,”Chin.Sci.Bull.53,676-680(2008).
27.J.Peng,L.Zhan,S.Luo,and Q.Shen,“Passive harmonic modelocking of dissipative solitons in a normal-dispersion Er-doped fiber laser,”J.Lightwave Technol.31,2709-2714(2013).
28.Y.Lyu,H.Shi,C.Wei,H.Li,J.Li,and Y.Liu,“Harmonic dissipative soliton resonance pulses in a fiber ring laser at different values of anomalous dispersion,”Photon.Res.5,612-616(2017).
29.G.Semaan,A.Niang,M.Salhi,and F.Sanchez,“Harmonic dissipative soliton resonance square pulses in an anomalous dispersion passively mode-locked fiber ring laser,”Laser Phys.Lett.14,055401(2017).
30.X.Li,S.Zhang,Y.Meng,and Y.Hao,“Harmonic mode locking counterparts of dark pulse and dark-bright pulse pairs,”Opt.Express 21,8409-8416(2013).
31.J.Q.Zhao,Y.G.Wang,P.G.Yan,S.C.Ruan,G.L.Zhang,H.Q.Li,and Y.H.Tsang,“An L-band graphene-oxide mode-locked fiber laser delivering bright and dark pulses,”Laser Phys.23,075105(2013).
32.R.Lin,Y.Wang,P.Yan,G.Zhang,J.Zhao,H.Li,S.Huang,G.Cao,and J.Duan,“Bright and dark square pulses generated from a graphene-oxide mode-locked ytterbium-doped fiber laser,”IEEEPhoton.J.6,1500908(2014).
33.G.Semaan,F.B.Braham,J.Fourmont,M.Salhi,F.Bahloul,and F.Sanchez,“10μJ dissipative soliton resonance square pulse in a dual amplifier figure-of-eight double-clad Er:Yb mode-locked fiber laser,”Opt.Lett.41,4767-4770(2016).
34.J.Zhao,D.Ouyang,Z.Zheng,M.Liu,X.Ren,C.Li,S.Ruan,and W.Xie,“100 W dissipative soliton resonances from a thulium-doped double-clad all-fiber-format MOPA system,”Opt.Express 24,12072-12081(2016).
35.C.Shang,X.Li,Z.Yang,S.Zhang,M.Han,and J.Liu,“Harmonic dissipative soliton resonance in an Yb-doped fiber laser,”J.Lightwave Technol.36,4932-4935(2018).
36.A.Komarov,F.Amrani,A.Dmitriev,K.Komarov,and F.Sanchez,“Competition and coexistence of ultrashort pulses in passive modelocked lasers under dissipative-soliton-resonance conditions,”Phys.Rev.A 87,023838(2013).
37.J.Liu,Y.Chen,P.Tang,C.Xu,C.Zhao,H.Zhang,and S.Wen,“Generation and evolution of mode-locked noise-like square-wave pulses in a large-anomalous-dispersion Er-doped ring fiber laser,”Opt.Express 23,6418-6427(2015).
38.J.Zhao,L.Li,L.Zhao,D.Tang,and D.Shen,“Dissipative soliton resonances in a mode-locked holmium-doped fiber laser,”IEEE Photon.Technol.Lett.30,1699-1702(2018).
39.L.Zhao,D.Li,L.Li,X.Wang,Y.Geng,D.Shen,and L.Su,“Route to larger pulse energy in ultrafast fiber lasers,”IEEE J.Sel.Top.Quantum Electron.24,8800409(2018).
40.P.K.Gupta,C.P.Singh,A.Singh,S.K.Sharma,P.K.Mukhopadhyay,and K.S.Bindra,“Chair-like pulses in an all-normal dispersion ytterbium-doped mode-locked fiber laser,”Appl.Opt.55,9961-9967(2016).
41.D.Mao,X.Liu,L.Wang,H.Lu,and L.Duan,“Dual-wavelength step-like pulses in an ultra-large negative-dispersion fiber laser,”Opt.Express 19,3996-4001(2011).
42.J.Zhao,L.Li,L.Zhao,D.Tang,and D.Shen,“Cavity-birefringencedependent h-shaped pulse generation in a thulium-holmium-doped fiber laser,”Opt.Lett.43,247-250(2018).
43.H.Luo,F.Liu,J.Li,and Y.Liu,“High repetition rate gain-switched Ho-doped fiber laser at 2.103μm pumped by h-shaped mode-locked Tm-doped fiber laser at 1.985μm,”Opt.Express 26,26485-26494(2018).
44.F.Haxsen,D.Wandt,U.Morgner,J.Neumann,and D.Kracht,“Monotonically chirped pulse evolution in an ultrashort pulse thuliumdoped fiber laser,”Opt.Lett.37,1014-1016(2012).
45.M.S.Kang,N.Y.Joly,and P.St.J.Russell,“Passive mode-locking of fiber ring laser at the 337th harmonic using gigahertz acoustic core resonances,”Opt.Lett.38,561-563(2013).
46.Q.Kuang,L.Zhan,Z.Wang,and M.Huang,“Up to the 1552nd order passively harmonic mode-locked Raman fiber laser,”IEEE Photon.Technol.Lett.27,2205-2208(2015).
47.G.P.Agrawal,Nonlinear Fiber Optics,5th ed.(Elsevier,2013).
48.N.J.Doran and D.Wood,“Nonlinear-optical loop mirror,”Opt.Lett.13,56-58(1988).
2.H.Zhang,Q.Bao,D.Tang,L.Zhao,and K.Loh,“Large energy soliton erbium-doped fiber laser with a graphene-polymer composite mode locker,”Appl.Phys.Lett.95,141103(2009).
3.H.Zhang,D.Y.Tang,L.M.Zhao,Q.L.Bao,and K.P.Loh,“Large energy mode locking of an erbium-doped fiber laser with atomic layer graphene,”Opt.Express 17,17630-17635(2009).
4.Z.Sun,T.Hasan,F.Torrisi,D.Popa,G.Privitera,F.Wang,F.Bonaccorso,D.M.Basko,and A.C.Ferrari,“Graphene mode-locked ultrafast laser,”ACS Nano 4,803-810(2010).
5.Z.Sun,D.Popa,T.Hasan,F.Torrisi,F.Wang,E.J.R.Kelleher,J.C.Travers,V.Nicolosi,and A.C.Ferrari,“A stable,wideband tunable,near transform-limited,graphene-mode-locked,ultrafast laser,”Nano Res.3,653-660(2010).
6.C.Zhao,Y.Zou,Y.Chen,Z.Wang,S.Lu,H.Zhang,S.Wen,and D.Tang,“Wavelength-tunable picosecond soliton fiber laser with topological insulator:Bi2Se3as a mode locker,”Opt.Express 20,27888-27895(2012).
7.Y.Chen,M.Wu,P.Tang,S.Chen,J.Du,G.Jiang,Y.Li,C.Zhao,H.Zhang,and S.Wen,“The formation of various multi-soliton patterns and noise-like pulse in a fiber laser passively mode-locked by a topological insulator based saturable absorber,”Laser Phys.Lett.11,055101(2014).
8.P.Yan,R.Lin,H.Chen,H.Zhang,A.Liu,H.Yang,and S.Ruan,“Topological insulator solution filled in photonic crystal fiber for passive mode-locked fiber laser,”IEEE Photon.Technol.Lett.27,264-267(2015).
9.Y.Chen,G.Jiang,S.Chen,Z.Guo,X.Yu,C.Zhao,H.Zhang,Q.Bao,S.Wen,D.Tang,and D.Fan,“Mechanically exfoliated black phosphorus as a new saturable absorber for both Q-switching and modelocking laser operation,”Opt.Express 23,12823-12833(2015).
10.Z.Luo,M.Liu,Z.Guo,X.Jiang,A.Luo,C.Zhao,X.Yu,W.Xu,and H.Zhang,“Microfiber-based few-layer black phosphorus saturable absorber for ultra-fast fiber laser,”Opt.Express 23,20030-20039(2015).
11.Y.Song,S.Chen,Q.Zhang,L.Li,L.Zhao,H.Zhang,and D.Tang,“Vector soliton fiber laser passively mode locked by few layer black phosphorus-based optical saturable absorber,”Opt.Express 24,25933-25942(2016).
12.Z.Wang,Y.Xu,S.C.Dhanabalan,J.Sophia,C.Zhao,C.Xu,Y.Xiang,J.Li,and H.Zhang,“Black phosphorus quantum dots as an efficient saturable absorber for bound soliton operation in an erbium doped fiber laser,”IEEE Photon.J.8,1503310(2016).
13.X.Jiang,S.Liu,W.Liang,S.Luo,Z.He,Y.Ge,H.Wang,R.Cao,F.Zhang,Q.Wen,J.Li,Q.Bao,D.Fan,and H.Zhang,“Broadband nonlinear photonics in few-layer MXene Ti3C2Tx(T=F,O,or OH),”Laser Photon.Rev.12,1700229(2018).
14.S.Chouli and P.Grelu,“Rains of solitons in a fiber laser,”Opt.Express17,11776-11781(2009).
15.X.Liu,X.Yao,and Y.Cui,“Real-time observation of the buildup of soliton molecules,”Phys.Rev.Lett.121,023905(2018).
16.H.Zhang,D.Y.Tang,L.M.Zhao,and X.Wu,“Dark pulse emission of a fiber laser,”Phys.Rev.A 80,045803(2009).
17.W.Chang,A.Ankiewicz,J.M.Soto-Crespo,and N.Akhmediev,“Dissipative soliton resonances,”Phys.Rev.A 78,023830(2008).
18.X.Wu,D.Y.Tang,H.Zhang,and L.M.Zhao,“Dissipative soliton resonance in an all-normal-dispersion erbium-doped fiber laser,”Opt.Express 17,5580-5584(2009).
19.C.Mou,R.Arif,A.Rozhin,and S.Turitsyn,“Passively harmonic mode locked erbium doped fiber soliton laser with carbon nanotubes based saturable absorber,”Opt.Mater.Express 2,884-890(2012).
20.J.Du,S.M.Zhang,H.F.Li,Y.C.Meng,X.L.Li,and Y.P.Hao,“L-band passively harmonic mode-locked fiber laser based on a graphene saturable absorber,”Laser Phys.Lett.9,896-900(2012).
21.Z.Luo,M.Liu,H.Liu,X.Zheng,A.Luo,C.Zhao,H.Zhang,S.Wen,and W.Xu,“2 GHz passively harmonic mode-locked fiber laser by a microfiber-based topological insulator saturable absorber,”Opt.Lett.38,5212-5215(2013).
22.M.Liu,A.Luo,W.Xu,and Z.Luo,“Coexistence of bound soliton and harmonic mode-locking soliton in an ultrafast fiber laser based on MoS2-deposited microfiber photonic device,”Chin.Opt.Lett.16,020008(2018).
23.Y.Wang,D.Mao,X.Gan,L.Han,C.Ma,T.Xi,Y.Zhang,W.Shang,S.Hua,and J.Zhao,“Harmonic mode locking of bound-state solitons fiber laser based on MoS2saturable absorber,”Opt.Express 23,205-210(2015).
24.B.Zhao,D.Y.Tang,P.Shum,W.S.Man,H.Y.Tam,Y.D.Gong,and C.Lu,“Passive harmonic mode locking of twin-pulse solitons in an erbium-doped fiber ring laser,”Opt.Commun.229,363-370(2004).
25.L.M.Zhao,D.Y.Tang,T.H.Cheng,C.Lu,H.Y.Tam,X.Q.Fu,and S.C.Wen,“Passive harmonic mode locking of soliton bunches in a fiber ring laser,”Opt.Quantum Electron.40,1053-1064(2008).
26.L.M.Zhao,D.Y.Tang,T.H.Cheng,H.Y.Tam,and C.Lu,“Passive harmonic mode locking of gain-guided solitons in erbium-doped fiber lasers,”Chin.Sci.Bull.53,676-680(2008).
27.J.Peng,L.Zhan,S.Luo,and Q.Shen,“Passive harmonic modelocking of dissipative solitons in a normal-dispersion Er-doped fiber laser,”J.Lightwave Technol.31,2709-2714(2013).
28.Y.Lyu,H.Shi,C.Wei,H.Li,J.Li,and Y.Liu,“Harmonic dissipative soliton resonance pulses in a fiber ring laser at different values of anomalous dispersion,”Photon.Res.5,612-616(2017).
29.G.Semaan,A.Niang,M.Salhi,and F.Sanchez,“Harmonic dissipative soliton resonance square pulses in an anomalous dispersion passively mode-locked fiber ring laser,”Laser Phys.Lett.14,055401(2017).
30.X.Li,S.Zhang,Y.Meng,and Y.Hao,“Harmonic mode locking counterparts of dark pulse and dark-bright pulse pairs,”Opt.Express 21,8409-8416(2013).
31.J.Q.Zhao,Y.G.Wang,P.G.Yan,S.C.Ruan,G.L.Zhang,H.Q.Li,and Y.H.Tsang,“An L-band graphene-oxide mode-locked fiber laser delivering bright and dark pulses,”Laser Phys.23,075105(2013).
32.R.Lin,Y.Wang,P.Yan,G.Zhang,J.Zhao,H.Li,S.Huang,G.Cao,and J.Duan,“Bright and dark square pulses generated from a graphene-oxide mode-locked ytterbium-doped fiber laser,”IEEEPhoton.J.6,1500908(2014).
33.G.Semaan,F.B.Braham,J.Fourmont,M.Salhi,F.Bahloul,and F.Sanchez,“10μJ dissipative soliton resonance square pulse in a dual amplifier figure-of-eight double-clad Er:Yb mode-locked fiber laser,”Opt.Lett.41,4767-4770(2016).
34.J.Zhao,D.Ouyang,Z.Zheng,M.Liu,X.Ren,C.Li,S.Ruan,and W.Xie,“100 W dissipative soliton resonances from a thulium-doped double-clad all-fiber-format MOPA system,”Opt.Express 24,12072-12081(2016).
35.C.Shang,X.Li,Z.Yang,S.Zhang,M.Han,and J.Liu,“Harmonic dissipative soliton resonance in an Yb-doped fiber laser,”J.Lightwave Technol.36,4932-4935(2018).
36.A.Komarov,F.Amrani,A.Dmitriev,K.Komarov,and F.Sanchez,“Competition and coexistence of ultrashort pulses in passive modelocked lasers under dissipative-soliton-resonance conditions,”Phys.Rev.A 87,023838(2013).
37.J.Liu,Y.Chen,P.Tang,C.Xu,C.Zhao,H.Zhang,and S.Wen,“Generation and evolution of mode-locked noise-like square-wave pulses in a large-anomalous-dispersion Er-doped ring fiber laser,”Opt.Express 23,6418-6427(2015).
38.J.Zhao,L.Li,L.Zhao,D.Tang,and D.Shen,“Dissipative soliton resonances in a mode-locked holmium-doped fiber laser,”IEEE Photon.Technol.Lett.30,1699-1702(2018).
39.L.Zhao,D.Li,L.Li,X.Wang,Y.Geng,D.Shen,and L.Su,“Route to larger pulse energy in ultrafast fiber lasers,”IEEE J.Sel.Top.Quantum Electron.24,8800409(2018).
40.P.K.Gupta,C.P.Singh,A.Singh,S.K.Sharma,P.K.Mukhopadhyay,and K.S.Bindra,“Chair-like pulses in an all-normal dispersion ytterbium-doped mode-locked fiber laser,”Appl.Opt.55,9961-9967(2016).
41.D.Mao,X.Liu,L.Wang,H.Lu,and L.Duan,“Dual-wavelength step-like pulses in an ultra-large negative-dispersion fiber laser,”Opt.Express 19,3996-4001(2011).
42.J.Zhao,L.Li,L.Zhao,D.Tang,and D.Shen,“Cavity-birefringencedependent h-shaped pulse generation in a thulium-holmium-doped fiber laser,”Opt.Lett.43,247-250(2018).
43.H.Luo,F.Liu,J.Li,and Y.Liu,“High repetition rate gain-switched Ho-doped fiber laser at 2.103μm pumped by h-shaped mode-locked Tm-doped fiber laser at 1.985μm,”Opt.Express 26,26485-26494(2018).
44.F.Haxsen,D.Wandt,U.Morgner,J.Neumann,and D.Kracht,“Monotonically chirped pulse evolution in an ultrashort pulse thuliumdoped fiber laser,”Opt.Lett.37,1014-1016(2012).
45.M.S.Kang,N.Y.Joly,and P.St.J.Russell,“Passive mode-locking of fiber ring laser at the 337th harmonic using gigahertz acoustic core resonances,”Opt.Lett.38,561-563(2013).
46.Q.Kuang,L.Zhan,Z.Wang,and M.Huang,“Up to the 1552nd order passively harmonic mode-locked Raman fiber laser,”IEEE Photon.Technol.Lett.27,2205-2208(2015).
47.G.P.Agrawal,Nonlinear Fiber Optics,5th ed.(Elsevier,2013).
48.N.J.Doran and D.Wood,“Nonlinear-optical loop mirror,”Opt.Lett.13,56-58(1988).