Investigation Of OPO Characteristics Pumped By Dual-loss Modulated Lasers

As a method to obtain lasers with different waveband,nonlinear laser frequency conversion has received wide attentions since it firstly achieved.Up to now,many kinds of optical nonlinear effects have been discovered and studied,for example,many three wave interaction process such as second harmonic generation(SHG),different frequency generation(DFG),sum-frequency generation(SFG)and optical parametric oscillator(OPO),many four wave interaction process such as such as stimulated Raman scattering(SRS),four-wave mixing(FWM)and stimulated Brillouin scattering(SBS),ect..With the development of nonlinear optical crystal growth technology,various kinds of nonlinear frequency conversion technology based on excellent nonlinear optical crystal are gained wide attentions from researchers,among these technologies,OPO and SRS are gained more attentions due to their advantages for acquiring medium infrared band coherent light source.Due to the advantages of simple structure and high conversion efficiency,laser-diode pumped all solid state Q-swiched lasers or Q-switched and mode-locked(QML)lasers have important applications on optical communication,laser ranging,machining and laser medical treatment.However,the problems of wide pulse widths,low pulse peak powers and poor pulse stability also limited their applications in further fields.With the advent of dual-loss modulation technology,the laser-diode pumped all solid state dual loss modulated Q-swithced or Q-switched and mode-locked lasers greatly compressed the pulse widths and improved the pulse peak powers,as well as increased the pulse stability.In this dissertation,we combining the dual-loss modulated technology and OPO operation to obtain OPO signal waves with high peak powers,short pulse widths and high pulse stability.In this dissertation,by employing a diode laser as pump laser,a YVO4/Nd:YVO4 crystal as gain medium,AOM-Cr4+:YAG doubly Q-switched and mode-locked laser and Q-switched laser were obtained respectively,besides,by using them as pump lasers,a KTP-based intracavity OPO and a KTA-based idler-resonant intracavity OPO were achieved,respectively.Furthermore,some related coupled rate equations were established and solved,the theoretical numerical simulation results were consistent with the experimental results;We obtained AOM Q-switched laser pumped KTP-based simultaneously OPO and SRS operations,by solving the related coupled rate equations,the simulation results agreed with the experimental results;The AOM-SWCNT doubly Q-switched and Q-switched and mode-locked lasers pumped intracavity KTP-OPO were obtained,respectively,the corresponding shortest pulse width were 1.18 ns and 119 ps,respectively;We obtained AOM-monolayer,AOM-MoS2 and AOM-WS2 doubly Q-switched laser pumped intracavity KTP-OPO,respectively,the corresponding shortest pulse width were 1.24 ns,850 ps and 810 ps,respectively.The main aspects and innovations of this dissertation are as following:1.By varing the small signal transmittance of Cr4+:YAG saturable absorber and the reflectivity of output mirror about signal wave,we studied the output characteristics of AOM-Cr4+:YAG doubly Q-switching and mode-locked laser pumped intracavity KTP-OPO.With an incident pump power of 8.3 W,an AOM repetition of 15 kHz,an output mirror reflectivity of 85%and a small signal transmittance of Cr4+:YAG saturable absorber of 93%,OPO signal wave with single mode-locking pulse underneath the Q-switching envelope was obtained,the shortest pulse duration was as short as 220 ps.Besides,the theoretical numerical simulation results were consistent with the experimental results.2.We firstly demonstrated an AOM-Cr4+:YAG doubly Q-switched laser pumped idler-resonant intracavity KTA-OPO.Signal wave and ider wave with wavelength of 1535 nm and 3467 nm were obtained.In comparison with AOM Q-switched laser pumped idler-resonant intracavity KTA-OPO,the doubly Q-switched laser pumped KTA-OPO can obtain signal wave and idler wave with shorter pulse durations.The shortest pulse duration of signal wave and idler wave were 898 ps and 2.9 ns,respectively.Furthermore,we built and solved the related coupled rate equations,and the theoretical numerical simulation results were consistent with the experimental results.3.We firstly realized an AOM Q-switched Nd:LGGG laser pumped KTP-based simultaneous OPO and SRS operaton.First-order Stokes radiation with wavelength of 1093.5 nm,second-order Stokes radiation with wavelength of 1125.8 nm and OPO signal wave with wavelength of 1570 nm were obtained,respectively.At an incident pump power of 9.25 W and an AOM repetition rate of 3 kHz,total of 98 mW output power for first and second order Stokes radiations and 375 mW output power for signal wave were obtained,respectively,in according with total optical to optical conversion efficiency of 5.1%.Besides,the numerical simulation results were consistent with the experimental results.4.We firstly demonstrated an AOM-SWCNT doubly Q-switched laser pumped intracavity KTP-OPO.With an incident pump power of 8.3 W and an AOM repetition rate of 20 kHz,signal wave with output power of 375 mW was obtained,in according with the optical to optical conversion efficiency of 4.5%.With the same incident pump power and an AOM repetition rate of 10 kHz,the shortest pulse width of 1.18 ns was obtained.Moreover,in comparison with AOM Q-switched laser pumped KTP-OPO,the doubly Q-switched laser pumped OPO has shorter signal wave pulse width,higher peak power and more stable pulse train.5.We first demonstrated an AOM-SWCNT doubly Q-switched and mode-locked laser pumped intracavity KTP-OPO.With an incident pumped power of 8.3 W and an AOM repetition rate of 2 kHz,signal wave with single mode-locking pulse underneath the Q-switching envelope was obtained,the shortest pulse width of mode-locking pulse was 119 ps,in according with the highest single pulse energy of 124μJ and the highest peak power of 1.04 MW.6.We first achieved an AOM-monolayer graphene doubly Q-switched laser pumped intracavity KTP-OPO.With an incident pump power of 11.7 W and an AOM repetition rate of 10 kHz,signal wave with the shortest pulse width of 1.24 ns was obtained,in according with the single pulse energy and peak power of 9.5 μJ and 7.9 kW.In comparison with AOM Q-switched laser pumped KTP-OPO,the doubly Q-switched laser pumped OPO can obtain shorter pulse width and higher peak power.7.We applied the layered MoS2 saturable absorber made by liquid phase separation method in all solid state of 1 μm laser.At an incident pump power of 6.54 W,the highest output power of 1.15 W with the shortest pulse width of 70.6 ns was obtained.Besides,by combining dual-loss modulation technology and OPO operation,AOM-MoS2 hybrid Q-switched laser pumped KTP-OPO was firstly achieved.With an incident pump power of 10.2 W and an AOM repetition rate of 10 kHz,signal wave with output power of 183 mW and pulse width as short as 850 ps were obtained.8.We studied the output characteristics of layered WS2 saturable absorber made by liquid phase separation method on all solid state of 1μm laser.At an incident pump power of 6.54 W,the highest output power of 1.18 W with the shortest pulse width of 53 ns was obtained.Besides,by combining dual-loss modulation technology and OPO operation,AOM-WS2 hybrid Q-switched laser pumped KTP-OPO was firstly achieved.With an incident pump power of 10.2 W and an AOM repetition rate of 10 kHz,signal wave with output power of 233 mW and pulse width as short as 810 ps were obtained.