| LD pumped solid-state lasers have become the central focus of recent researches, due totheir simple structure, high efficiency, stable property. Laser crystal and the saturable absorber(SA) play a major part during the developmental stages of the LD pumped solid-state lasers.Scandium Silicate (Sc2SiO5, SSO) which belongs to silicate oxide crystals, has excellentproperties of negative refractive index temperature gradient, high thermal conductivity andbroad emission cross section was proved to be a promising crystal to achieve LD pumpedsolid-state lasers. The carbon nanotube and graphene saturable absorbers are becoming hotrares of research gradually for low manufacturing cost, wide modulated range and shortrecovery time. The study shows that by doping Yb3+at1μm and Tm3+at2μm into the SSOcrystal respectively, both have obtained laser crystal of excellent properties. In this article, westudied the features of the two gain media pulsed laser, researched the spectral ofTm3+:Sc2SiO5and made a comprehensive characterization of laser properties. The severalaspects of research contents are as follows:1. We introduced the characteristics and the development of the SSO based crystal,Tm3+and Yb3+, concluded the spectrum characteristic of Tm3+:Sc2SiO5(Tm:SSO) andYb3+:Sc2SiO5(Yb:SSO) laser crystals. Moreover, we listed the advantages, preparationmethods of Single-walled carbon nanotubes (SWCNTs) and graphene saturable absorbers.2. We analyzed the properties of diode-pumped continuous and passively Q-switchedTm:SSO lasers. The continuous laser operation of Tm:SSO was realized firstly by using asimple linear cavity. The obtained maximum output power was0.932W. The correspondingoptical-optical conversion and slope efficiencies were20.6%and29.4%, respectively. Then,by using a V-cavity, the passively Q-switched laser of Tm:SSO was realized with aSWCNT-SA. The laser has a maximum average output power of189mW and a shortest pulsewidth of442ns with a frequency repetition of55.6kHz, corresponding to the highest singlepulse energy of3.4μJ and the central wavelength of1971nm.3. The performances of diode-pumped passively mode-locked Tm:SSO laser wasstudied. First, we realized the passively Q-switched mode-locked laser of Tm:SSO with asingle-walled carbon nanotubes as the saturable absorber. Under the absorbed pump power of3.9W, the maximum average output power of195mW was obtained. The Q-switched pulse envelope was4μs, and the duration of the mode-locked pulse of sub-100ps with a frequencyrepetition of92.6kHz. The corresponding central wavelength was1967nm with a broadspectral region of23nm. Secondly, by using the excellent graphene as the saturable absorber,we demonstrated the mode-locked laser of Tm:SSO and achieved the passively Q-switchedmode-locked laser. Under the same pump power, the maximum average output power of240mW and the mode-locked frequency repetition of74MHz were obtained. The results indicatethat the Tm:SSO crystal was a novel promising candidate for ultrafast lasers at2μm.4. We successfully used the graphene-SAs to generate the ultrafast Yb:SSO lasers. Themaximum average output power of Yb:SSO/transmission-type graphene-SA laser was480mW, the pulse duration, frequency repetition and peak power was14ps,90.7MHz and0.38kW, respectively. And the corresponding central wavelength of1063nm with a spectralregion of1.9nm. The maximum average output power of Yb:SSO/reflection-typegraphene-SA laser was352mW, the pulse duration, frequency repetition and peak power was7ps,97MHz and0.52kW, respectively. And the corresponding central wavelength was1063nm with a spectral region of1.7nm. |
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