Research On Self-mode-lcoked Self-stimulated Raman Laser

With the in-depth innovation and progress of all-solid-state laser,the scientific researchers not only study the ultra-short laser field,but also explore more and more laser wavelengths.The self-mode locked(SML)technology is attribute to the third-order Kerr nonlinearity(or intensity-dependent index of refraction).In the last ten years,the picosecond self mode locking has been verified continually in the kinds of crystals,which can be a potential light source in many fields,such as communication,medical and bio-medical arena,micro-nano fabrication,nonlinear optical transformation,optical clock.The stimulated Stokes Raman scattering(SRS)process is also relevant to the third-order nonlinearity.Therefore,it can be an efficiency nonlinear optical frequency conversion technology to generate many new near-infrared wavelengths.Since the 21th century,a novel self-Raman laser has been reported.Namely,only one crystal has the functions of gain medium and Raman medium with the advantage of the smaller volume and more stable operation,which has been an international research focus in the Raman laser field.In terms of the main challenges and the research direction of all-solid-state SML laser and self-Raman laser lasers,in this dissertation,the theories and experiments of picosecond SML laser are studied firstly in domestic with Nd:YVO4 and Nd:GdVO4 crystals,which fill the gaps in the picosecond SML field.Furthermore,combining the SML technolog with the self-stimulated Raman technology creatively,a SML self-Raman laser is demonstrated.Besides,the external yellow laser is also obtained.The main contents are as follows:Firstly,the key theories of SML laser and design rules are studied and numerical simulated,including the influence of thermal effect,the criterions for stable SML laser and the self-started criterion of SML laser.The nonlinear dynamics of a SML laser is investigated.Furthermore,the dynamic processes of SML self-stimulated Raman laser are theoretically studied,and author self-explore the design rules of these laser.Finally,the vortex laser obtained with astigmatic mode converters is studied,which affords the theoretical foundation of vortex laser.Secondly,efficient sub-gigahertz SML picosecond laser are demonstrated and studied,which gathers experience for subsequent experiments.First,the triple repetition rate of SML laser is obtained with an asymmetric z-shape cavity.The output power is up to 2 W with optic-optic efficiency of 25%.Next we have further designed a z-shaped cavity to obtain the stable SML laser.The maximum output power is 1.65 W,with a slope efficiency of 23.8%.The ML repetition rate and pulse width are 530 MHz and 15.1 ps,respectively.Thirdly,a stable SML green laser is demonstrated.An optimum experimental scheme is first decided through the comparison of different cavity lengths for the stability of SML green laser.Based on the aforementioned scheme,the operation of stable picosecond 532 nm laser is obtained with a concave-flat cavity,the influences of other intracavity nonlinear effect on the the stability of SML laser have been investigated,which gather experience for subsequent experiments.The average output power of stable ML 532 nm laser is 258 mW with a slope efficiency of 4.5%.The ML repetition rate is 1.1 GHz and the average fluctuation of ML laser amplitude is less than 8%.Fourthly,the innovative high-Kerr-sensitivity SML self-Raman laser are studied based on the aforementioned experiments,i.e.a single crystal possesses the roles of gain medium,Raman medium and passively mode-lcoked(ML)element.First,with the Nd:YVO4 crystal,the picosecond 1176 nm self-Raman laser is accomplished.The average output power,repetition rate and slope efficiency are 643 mW?1.53 GHz.5.3%and 8.2%,respectively.And the fundmental laser pulse is 8.6 ps.Additionally,with the external frequency technology of LiB3O5,the yellow laser output power of 6 mW is obtained.Next,picosecod 1173 nm SML laser is fulfilled with Nd:GdVO4 crystal.The ML average outout power,repetition rate,slope efficiency,fundmental pulse width and yellow laser are 736 mW?1.51 GHz?8.3%?12.5 ps and 7.65 mW,respectively.Fifthly,a SML Nd:YV04 picosecond vortex laser oscillating on the Laguerre-Gaussian(LG)modes at 1064 nm is demonstrated with a external ?/2 mode converter.For the presnt laser,the stable high-order Hermite-Gaussian(HG)modes of self mode-locked vortex laser are obtained on the order of 02.The average output power,the slope efficiency of LG02 mode mode-locked pulse repetition rate and are 1.27 W,24%and 1.81 GHz,respectively.