Research On CVD-diamond Based Raman Lasers

As a kind of frequency conversion way,Stimulated Raman scatterings(SRS)is a coherent strong excitation process,belonging to the third order nonlinear effect.With different pump wavelength and Raman medium,stimulated Raman scattering laser from uv to the near infrared range obtained,thus,it greatly extended the scope of laser spectrum.In addition,SRS has lots of attractive features,such as beam clean-up,no need for phase matching and so on.A larger number of crystals,such as the tungstate crystals,Ba(NO3)2,LiIO3,Vanadate crystal and so on,offer excellent stimulated Raman properties.Owing to compact structure,good stability and high efficiency,Raman lasers have lots of applications in the fields of information transportation,medical treatment,industry,national defense and agriculture and so on.Compared with the common Raman crystal,the CVD-diamond crystal has lots of outstanding properties,such as the exceptional thermal conductivity,high damage threshold,and broad transparency provide excellent prospects for a range of efficient,compact,and high-power laser devices.The 1333 cm-1 Raman frequency,which is notably larger than other Raman crystals,provides a first Stokes wavelength of 1240 nm for 1064 nm pumping.Based on the CVD-diamond crystal as the Raman crystal,The first three chapters suggest that the first-Stokes form 1064 nm and 532 nm pumped to 1240 nm and 573 nm was studied.The fourth chapter suggest that Gold nanobipyramids as a saturable absorber for passively Q-switched Yb-doped fiber laser operation at 1.06 ?m and Gold nanobipyramid Q-switched Nd:LGGG eye-safe laser operating at 1.4 ?m The following are the contents of this paper:1.Considering the emission principle of stimulated Raman scattering,the model of multi Raman laser resonator is established,and the characteristics of CVD-diamond crystal are analyzed and compared..2.Based on CVD-diamond crystal,an efficient 1240 nm external cavity Raman laser operating on the 1nd Stokes shift of a 1.064 ?m Fiber laser 133.5W pulsed at pump power 193 W is produced with a conversion efficiency of 69.1% and excellent beam quality.Pump threshold power is 12 W,when the pump power is 62 W,achieving maximum output power of 15.6 W,the corresponding light conversion efficiency of 25.1%.3.An external cavity CVD-diamond Raman laser pumped by a Q-switched 1064 nm fiber laser was demonstrated.Output pulses of wavelength 1240 nm with a combined power of 14.9 W were obtained and a maximum of conversion efficiency up to 38% at maximum pump power 49 W,pulse repetition rate were 100 KHz,.Compared with continuous pump,under pulse pumped Raman output efficiency gain a certain degree of improvement.4.Gold nanobipyramids(Au-NBPs)are prepared using a seed-mediated growth method.The longitudinal surface plasmon resonance(SPR)absorption peak of the Au-NBPs is located at 1068 nm by controlling the aspect of the materials.Under the pumped power of 340 mW,the maximum average output power was 3.3 mW.The minimum pulse width is 2.6 ?s at a pulse repetition rate of 66.3 kHz.The results prove that Au-NBP are a promising SA with the potential for important applications in the field of pulse lasers.The performance of a laserdiode–pumped passively Q-switched Nd:LGGG laser at 1423.2 nm with gold nanobipyramids(Au-NBPs)as a saturable absorber was demonstrated.Under the pump power of 12.2 W,an average output power of 125 mW was obtained,corresponding to an optical-to-optical conversion efficiency of 1.36% and a slope efficiency of 1.78%.A minimum pulse width of 514 ns at a pulse repetition rate of 98.6 kHz was obtained at a pump power of 12.2 W.To the best of our knowledge,this is the first report focusing on the application of AuNBPs as a saturable absorber for pulse laser operation in the eye-safe region.