Ionic Liquid [BMIM]PF₆ Dye Doped Optofluidic Lasing And Its Application In PH Sensing

In this thesis,a bare quartz fiber was implanted into a polydimethylsiloxane(PDMS)substrate and pumped along the optical fiber axis.Then,the optofluidic lasing emission and lasing pH sensing of rhodamine B(RhB)in[BMIM]PF₆ ionic liquid was demonstrated.The concentration of RhB was fixed at 0.5 mM.The fluorescence stability of RhB in[BMIM]PF₆ ionic liquid and the mixed solvent of water and glycerol with the same refractive index were demonstrated under the same pump power using a CW laser with a wavelength of 532 nm.In addition,an optical parametric oscillator(OPO)laser with a wavelength of 532 nm was used as the pump light,the optofluidic laser emission of RhB in[BMIM]PF₆ was also studied.Finally,sodium hydroxide(NaOH)was added into the[BMIM]PF₆ ionic liquid to obtain a series of pH RhB ionic liquid solutions,the related fluorescence intensity,lasing intensity and lasing threshold of RhB in[BMIM]PF₆ ionic liquid were then presented.The main results of this thesis are as follows:Firstly,under the condition of the same pump power,the fluorescence and lasing stability of[BMIM]PF₆ ionic liquid dye doped RhB were better than that of the mixed solution of water and glycerol.Secondly,lasing emission of[BMIM]PF₆ ionic liquid dye doped RhB belonged to a transverse electric mode(transverse electric mode,TE)wave whispering gallery mode(Whispering Gallery Mode,WGM)lasing with different number of angular modes and the same radial modes.Finally,under the same pumping power or pumping energy density,the fluorescence intensity or lasing intensity of RhB decreased with the increase of the pH,the lasing emission was more sensitive than that of fluorescence.The sensitivity of the WGM lasing is about 7 times to that of the fluorescence.The laser threshold of RhB was increased linearly with the increase of the pH value.During the process of experiment,we also found that under the condition of the same pumping energy density,the central lasing wavelength was blue shifted with the increasing of the pH value,which was explained well by the WGM lasing theory.