Study On Optical Characteristics Of The Metal Nanoparticles Doped Multicomponent Phosphate Glass Fiber

High power and narrow linewidth are the future trend of fiber lasers along with the development of laser technology.The high power laser output can be obtained by increasing the doping concentration of rare earth.However,high concentration of rare earth ions will cause concentration quenching effect,which can seriously affect the performance of laser.Therefore,it is necessary to find other ways to obtain high gain coefficient of multicomponent glass fiber.Recently,metal nanoparticles have attracted intensive attention for their superior optical properties.Especially,the local surface plasmon of metal nanoparticles can enhance the local field near rare earth ions.The transition of rare earth ions is electric dipole transition,which is very sensitive to the local field.When the distance between silver NPs and rare earth ions is short enough,the rare earth ions around silver NPs can be activated,making the electronic excitation(or absorption)efficiency greatly improved.And the fluorescence emission can be enhanced.Moreover,when metal nanoparticles composite with other materials,new photoelectric materials with special photoelectric properties can be prepared,and have a good application in display,information storage,military and the realization of random laser.Thus the motivation of the present work is to search for a new way to further improve the gain coefficient of glass fiber.And a new material researched to achieve random laser.In this thesis,we have successfully introduced silver nanoparticles in the multicomponent phosphate glasses.The spectral properties and laser output characteristics of silver nanoparticles doped multicomponent phosphate glass and glass fiber were studied.In addition,the effect of scattering produced by silver nanoparticles in glass and fiber were also investigated.The research contents and results are as follows:(1)The effect of Ag NPs on the near-infrared luminescence properties of Er3+/Yb3+doped multicomponent phosphate glasses and some physical properties have also been systematically studied.Efficient 1.53 ?m emission was obtained in prepared samples when pumped at 980 nm laser diode(LD).The 1.53 ?m emission intensity could be enhanced 87% by doping 2 mol% AgCl.Combined with the electron energy level distribution,the reasons for the significant enhancement of 1.53 ?m band fluorescence were analyzed.The primary reason is the increased local field induced by Ag NPs.Another reason is the energy transfer from Ag NPs to rare earth ions.(2)Silver nanoparticles doped multicomponent phosphate glasses single mode fibers were fabricated by rod-in-tube technique,and the output of single-frequency lasers was realized.The obtained glass fiber featured with a core diameter of 9.08 ?m and cladding diameter 125 ?m.The measured propagation loss of the glass fiber at 1310 nm is 3.61 dB/m.The stable single-frequency lasers with the center wavelength at 1535 nm,was realized by using 1.8 cm glass fiber in a distributed Bragg reflector(DBR)cavity.The slope efficiency of the laser is 12.67 %.(3)The relative intensity noise(RIN)of the laser is measured by direct measurement method.The peak of the relaxation oscillation was located at about 1.76 MHz.As frequency increased,RIN decreases from-85 dB/Hz to-135 dB/Hz.The linewidth of the output of the fiber laser was measured to be around 55 kHz.(4)The experiments on random laser were respectively carried out by continuous light and femtosecond pulsed sources.Based on the multi-scattering of nanoparticles,the spatial light paths were respectively designed and built.And the effects on laser characteristics in the bulk glass,core club and fiber were also studied.Spectrums of three positions on the bulk core glass pumped by continuous light source 976 nm LD were investigated.The obtained spectrums were all about the near-infrared fluorescence spectral of Er3+ ions.And the fluorescence intensity changed with the pump power.Furthermore,the output spectrum of the bulk glass,core club and fiber were obtained under 976 nm femtosecond pulsed laser.All the obtained were amplified spontaneous emission spectrums,the desired output of random laser was not realized.The intensity of spontaneous emission increases with increasing the pump power.