All-solid-state Self-mode-locked Laser At 1.3?m

Diode pumped solid-state picosecond lasers have a wide range of applications,such as industrial processing,nonlinear frequency conversion,photobiology,spectroscopy,medical diagnostics.The self-mode-locking used as a new technical means for picosecond pulse has attracted much attention in the last few years,because of its simple equipment,high damage threshold,low cost,high reliability,wide range of wavelength,and narrow pulse-width.Compared with the wavelength of 1.0 ?m,the self-mode-locked picosecond laser at 1.3 ?m develops slowly.However,the wavelength of 1.3 ?m has a wide range of applications in spectroscopy,optical fiber communication,mid-infrared optical parametric oscillator.Besides,based on the 1.3 ?m laser system,highly efficient production of red radiation by frequency doubling plays an important role in the fields of medical treatment and laser display.Based on the facts above,the self-mode-locked picosecond laser at 1.3 ?m has been studied in this paper.In this dissertation,the combination of the Kerr effect of gain medium and the transverse soft-aperture served as a saturable absorber,the development of a high efficient stable self-mode-locked picosecond laser at 1.34 ?m is reported with the crystals of Nd:YVO4 and Nd:GdVO4.The main contents are as follows:Firstly,the developments of continuous mode-locking are introduced.Besides,we focus on the significance and development of the pulsed laser at 1.3 ?m.Secondly,in the foundation of the aberrationless theory,by analyzing the Kerr effect of gain medium,we describe the mechanism of pulse compression.Moreover,relations between the stability and the Kerr nonlinear strength are discussed.Thirdly,a high efficient stable Nd:YVO4 self-mode-locked picosecond laser at 1.34?m was realized in two types of cavities.On this basis,through comparing the different pump radius,we studied the proportion of the spot size at the pump beam to the spot size at the medium.When pump power is 10 W,the average power of the output pulse can reach 1.34 W.The corresponding light conversion efficiency and the slope efficiency are13.4%and 17.5%,respectively.The repetition frequency is 1.48 GHz,and the single pulse energy is 0.91 nJ.Fourthly,through studying the thermal effect of Nd:GdVO4 and effective Kerr nonlinear strength,the 1.34?m picosecond self-mode-locked Nd:GdVO4 watt-level laser was achieved.Meanwhile,we discussed that the different values of effective Kerr nonlinear strength have influence on the mode locked stability.The optical conversion efficiency and the slope efficiency for the stable mode-locked operation are approximately 16.7%and 19.2%,respectively.A pulse width as short as 9.1 ps is generated at a repetition rate of 2.0 GHz.The single pulse energy is 1.26 nJ,and the peak pulse power is about 137.9 W.