Research On LD-Pumped Er,Yb:YAB Passively Q-Switched Microchip Laser

The passive Q-switched Er,Yb:YAl₃（BO₃）₄（YAB）microchip laser pumped by laser diode is one of the effective ways to realize the operation of 1.5μm laser.LD pumped solid state laser has the advantages of high conversion rate,compact structure and high integration,and has a good application prospect in optical communication,industrial processing and biomedical fields.Passive Q-switched technique is beneficial to narrow pulse laser output with high repetition frequency and peak power.This paper first introduces the research background of the subject,analyzes the research significance of1.5μm band laser and the prospect of production and application.Several main methods of realizing 1.5μm laser operation at present are analyzed and compared.Then,according to the basic structure and optical properties of crystals,the advantages and reasons of choosing Er,Yb:YAB crystals and Co²⁺:Mg Al₂O₄crystals as Q-switched crystals are described.Finally,the continuous LD pumping and quasi-continuous LD pumping of Er,Yb:YAB passive Q-switched microplate laser with a center wavelength of976 nm are studied,and the stable 1.5μm pulse laser output is achieved.The main contents of this paper are as follows:1.Based on the theory of passive Q-switching rate equations,the computational expressions of parameters such as repetition frequency,pulse width and single pulse energy are derived.It is concluded that the output pulse performance of passive Q-switched laser is determined by several parameters.It is difficult to obtain the laser output with optimal pulse performance by selecting the optimal pump source,working material,Q-switched crystal or optical resonator parameters alone.It provides theoretical guidance for the optimal design of the experimental scheme in the following.2.The output characteristics of Er,Yb:YAB passively Q-switched laser under the condition of continuous LD pumping are studied.The highest output mirror transmittance exists in the case of saturable absorbent with different initial transmittance.The length of resonator affects the repetition frequency,peak power and pulse width of the output laser.The smaller the initial transmittance of saturated absorbent Co²⁺:MgAl₂O₄crystal is,the larger the monopulse energy is and the narrower the pulse width is.The continuous LD pumping Er,Yb:YAB passively q-switched experiment has successfully achieved a pulse laser output with a repetition rate of 200.1 k Hz and a peak power of 366.4 W.The corresponding pulse width is 8.7 ns and the single pulse energy is 3.8μJ.3.The output characteristics of Er,Yb:YAB passively Q-switched laser under the condition of quasi-continuous LD pumping are studied.When the pump power is 30 W and the duty cycle is 15%,the pulse width and single pulse energy are 7.4 ns and 3.2μJ,with an average output power of 2.7 W and a repetition rate of 663.0 k Hz.The experimental results show that the compact laser designed in this paper can achieve a stable high repetition 1.5μm laser output.