Research On LD-pumped Rare-earth-doped All-fiber Lasers

Fiber lasers hold for a variety of practical applications,including optical communication,laser processing,medical diagnosic,optical holography,spectroscopy,and scientific research.Benefiting from the high-energy and the narrow-pulse-width of all-fiber lasers,a great attentation is also paid to the visible pulsed all-fiber lasers.Compared to the mode-locking regime,the Q-switching not only has lower requirements of gain/loss and dispersion in fiber lasers and the performance of saturable absorbers(SAs),but also is characterized by higher pulse energy.It is easy to achive the Q-switching with lower-cost.Firstly,based on the Pr-doped and the Ho-doped all-fiber lasers,this work used the Q-switched technique to generate about sub-?s of pulse width and sub-?J of pulse energy in the visible region,which investigates the wideband visible saturable-absorption property of single-walled carbon nanotubes(SWNTs),and also the saturable-absorption of the active fiber itself.Secondly,this work used the specialty all-solid photonic bandgap fiber(AS-PBF)to investigate the efficient high-power?976 nm single-mode Yb-doped all-fiber lasers.The results are as follows.1.Red and deep-red SWNT-based passively Q-switched Pr-doped all-fiber lasers.The 635 nm nad 716 nm all-fiber mirrors were fabricated by the commercial fiber components and the dielectric films deposited on the fiber end-facets.The combination of 443 nm laser diode(LD)pumping and the SWNTs saturable absorber(SWNT-SA)constructed the compact visible pulsed Pr-doped all-fiber lasers.1.Investigated the first SWNT-SA bidirectional 635 nm passively Q-switched Pr-doped all-fiber ring lasers.In the clockwise(C.W.)operation,the pulse repetition rate can be tuned between 65,2 kHz and 143.0 kHz,and the narrowest pulse width is 1.35 ?s.In the counterclockwise(C.C.W.)operation,the pulse repetition rate can be changed from 67.8 to 96.5 kHz,and the narrowest pulse width is 1.51 ?s.Such a laser could find the versatile applications in gyroscopes,sensing,and the synthesis of optical waveforms.2.Investigated the first SWNT-SA 716 nm passively Q-switched Pr-doped all-fiber laser.The achieved pulse repetition rate is 32.6-86.5 kHz,and the narrowest pulse width and the maximum pulse energy are 2.3 ?s and 18.3 nJ,respectively.These results demonstrate SWNTs show the wideband saturable-absorption properties at visible wavelengths(e.g.,635 nm and 716 nm).?.Green and deep-red tunable self-Q-switched Ho-doped all-fiber lasers.Utilizing direct deposition of the dielectric films on the fiber end-facets,both red and deep-red all-fiber mirrors were prepared.Under the 450 nm LD pumping,the saturation absorotion of the Ho-doped fiber itself contributed to the compact visible tunable pulsed Ho-doped all-fiber lasers.1.Investigated the first green tunable self-Q-switched Ho-doped all-fiber laser at 543-550 nm.Based on different lengths of active fibers and different transmissions of output mirrors,the maximum output power is measured to be up to 150 mW at 550 nm.For the wavelength-tunable Q-switched operation,the achieved pulse repetition rate is between 80.19 kHz and 97.66 kHz,and the 605 ns of narrowest pulse width and the 196 nJ of maximum pulse enengy are measured.Such a work may be considered as an alternative candidate for the green frequency-doubled solid-state laser,which could facilitate the development of next generation of simple and high-efficient green all-fiber laser source.2.Investigated the first deep-red tunable self-Q-switched Ho-doped all-fiber laser at 754-758 nm.The maximum output power achieved is 16 mW at 758 nm.The Q-switched pulse performances,including the pulse repetition rate,the narrowest pulse width,and the maximum pulse energy,are 59.88-100.5 kHz,2.02 ?s,and 58 nJ,respectively.Such a technique could facilitate the availability of simple deep-red all-fiber laser source for the practical applications in bio-imaging,microscopy,and spectroscopy.?.976 nm high-power single-mode Yb-doped all-fiber lasers.Based on UV-induced fiber Bragg grating(FBG),the-976 nm FBG was prepared as the all-fiber cavity mirror.The combination of 915 nm LD pumping and the specialty AS-PBF contributed to the efficient high-power-976 nm single-mode Yb-doped fiber lasers.Investigated the first 80W single-mode output at-976 nm,and the M2 was measured to be 1.11.Investigated the first single-pumped 90W and double-pumped 150W single-mode all-fiber outputs at-976 nm.The maximum laser conversion efficiency is up to 66%in the three-level system and the M2 was measured to be<1.25.Such a high-power single-mode all-fiber laser could serve as a pump source of ultrafast solid-state lasers,and core pumping options for nonlinearity-limited fiber lasers.