Research On Compact All Solid State Single-frequency Green/brue Laser

The single-frequency laser source not only has the characteristics of the general laser source,but its significant advantage is that the single-frequency laser source has longer coherence length,narrower spectral line width and lower noise,which demonstrates considerable application prospect in many areas.In this paper,we mainly study the all-solid-state intracavity frequency-doubling Nd:YVO4 single-frequency green and blue laser.The main research contents are list as follows:1)The development of all-solid-state single-frequency laser technology is described.The popular used methods,such as the short cavity,coupling cavity,Etalon standard cavity,birefringent filter,ring cavity and twisted-mode cavity,are introduced respectively.Meanwhile their advantages and disadvantages are also analyzed.2)The characteristic analysis of Nd:YVO4:a brief introduction to the physical and laser characteristics of Nd:YVO4;the four levels(green laser)and the quasi-three level(blue ray)energy level system theory are analyzed carefully.The energy level structure and the main laser transition process of Nd:YVO4 are mainly discussed,and the input and output characteristics of Nd:YVO4 laser are also discussed.3)The second harmonic generation theory are expounded,and the several key factors influencing the frequency doubling conversion efficiency are analyzed,such as the fundamental frequency beam spot size,the pump power density,frequency-doubling crystal length,phase-matching conditions,etc.Then the key phase-matching conditions of the frequency-doubling laser are analyzed emphatically,and the theory of Angle phase-matching and temperature phase-matching and walk-off effect are respectively discussed.Then an optimal frequency conversion efficiency model is established and a brief analysis is completed.In the last section,the characteristics of the commonly used frequency-doubling crystal of KTP and LBO for green and blue laser are describled in detail.4)The all-solid-state intracavity frequency-doubled Nd:YVO4 single-frequency green/blue laser experiment are demonstrated:first of all,based on the birefringent filter frequency-selecting principle and Jones matrix,the propagation of polarized light in laser cavity is simulated with MATLAB,and the birefringent filter transmittance curve is plotted through Origin.The longer the frequency-doubling crystal length,the frequency-descrimation ability is stronger.and the temperature stability of the birefringent crystals is especially important for the stability of the oscillation frequency.In the experiment,we successfully realized the single frequency output of Nd:YVO4 green/blue laser with birefringent filter.When using fiber coupled 808nm laser diode as pump source,the stable single-frequency green output of 42 mW at 532 nm was obtained at 1.7 W pump power,at the pump power of 5.68 W,the output power of single-frequency blue laser at 457 nm reaches 17.3mW.