Development Of KHz LD Pumped Eo Q-Switch Laser And Frequency Convertion

The high repetition rate LD pump Q-switch solid state laser has been widely used in a lot of fields, such as the laser communication, optical storage, marking, welding and ranging radar. By the utilization of nonlinear frequency conversion, for example, implementing a frequency doubling on the near-infrared to get the Second Harmonic, a 532nm laser output can be generated, it could extend the applications in industry processing.On the basic of the rate equation, I studied the input and output properties of the LD pump laser and the variation of the population inversion densities when the Q-switch working. Thus to analyze the factors in the laser design which effect the properties of output laser, and then deeply discuss the EO Q-switch technology. At last, there is a brief instruction on the Second-harmonic generation and phase-matching theory, comparing the basic properties, advantages and disadvantages of all kinds of non-linear crystals, analyzing the factors that affect the harmonic conversion efficiency and the reasons causing the damage of non-linear crystals.Through researching the theory, we carried out side-pumped Nd: YAG EO Q-switch laser and end-pumped Nd: YVO₄ EO Q-switch laser respectively, then comparing the output results. Analysis of the similar experiments domestic and abroad in details, we know that in the commonly EO Q-switch laser are required to insert a polarization component in the cavity, an increase of cavity loss and cavity length. The experiment focuses on the polarization characteristic of Nd: YVO₄ crystal. In order to get a high efficiency and narrow pulse width in small-scale laser, choosing the LGS crystal as the voltage-decreased Q-switch component and using Nd:YVO₄ crystal which has a 10 degree wedge angle. This design has the advantages of simplifies the components in the cavity, shortens the cavity length and reduces the loss by saving the polarizer, that we can get a higher efficiency output and a narrower pulse width. A high repetition rate EO Q-switch solid state laser has been developed successfully. At a repetition rate of 1 kHz, the average power is 2.2W, 6.3ns pulse width, the optical-to-optical efficiency is 39.2%, and the peak power is more than 300kW in 1064nm output. On the basis of this, we do the extra-cavity-doubled experiment, used the high damage threshold LBO crystal, which got a 300mW green light output and the harmonic conversion efficiency is 45%.