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Study On Eye-safe 1.5?m High Repetition Rate Self-optical Parametric Oscillator

Posted on:2021-03-16Degree:MasterType:Thesis
Country:ChinaCandidate:H Y LiuFull Text:PDF
GTID:2428330611496390Subject:Physics
Abstract/Summary:PDF Full Text Request
1.4-2?m near infrared laser is in the eye-safe band.The 1.5?m band is not only less harmful to the human eye,but also the main transmission window of the atmosphere,which has an important application prospect in the military and civilian fields such as laser ranging,photoelectric countermeasure,laser medical treatment and so on.The quasi phase matched optical parametric oscillation technology?QPM-OPO,Quasi-Phase Matching Optical Parametric Oscillator?has great advantages such as high repetition rate,narrow pulse width and high peak power.With the development of optical parametric oscillation technology,the large volume and complex structure of lasers have appeared.Compared with the traditional 1.5?m eye-safe optical parametric oscillation technology,Nd3+is doped into MgO:PPLN crystal,and the gain medium and frequency conversion medium are combined into one,and a new technology for obtaining high repetition rate 1.5?m eye-safe laser is proposed,which is of great significance for the development of miniaturization and integration of high repetition rate eye-safe laser.Theoretically,quasi-phase matching is mainly used as the theoretical basis.The physicochemical and optical characteristics of Nd:MgO:LN crystals are analyzed,and the tuning curves of periodically polarized Nd:MgO:LN crystals are theoretically simulated.Subsequently,a temperature and stress field model of Nd:MgO:PPLN crystal was constructed,and the single-end and double-ended pump temperature and stress field distributions were simulated.Based on this,a temperature tuning curve was used to analyze the effect of the crystal temperature rise on the signal light wavelength Influence,the crystal polarization period was finally determined to be 29.8?m.In addition,the ABCD matrix was used to simulate the spot variation of the three wave light field,the pattern matching of the three wave light field was optimized,and the best parameters for the experimental setup were determined.Finally,the over-threshold multiple,the self-optical parameter oscillator passively Q-switched and actively Q-switchied rate equations were established to further optimize the frequency conversion parameters of the signal light.The stability of the fundamental light and the signal light repetition rate as well as the corresponding pulse width change are theoretically simulated.Experimentally,1.5?m self-parametric oscillation with end pumped at 813 nm related experiments were carried out.In the single-ended pumped passively Q-switched experiment,when the crystal absorbed the pump power of 12.8W,it achieved a signal light wavelength output of 1514 nm,with an average power of 210mW,a repetition rate of 5.4kHz,a pulse width of 6.1ns,and a peak power of 6kW.In the double-ended pumped high repetition rate acousto-optic Q-switched experiment,when the crystal absorbed the pump power at 19.5W,it achieved a 1512 nm signal light wavelength output,with an average output power of545mW,a maximum repetition rate of 100kHz,and a pulse width of 14.18 ns,peak power is 5.8kW,down-conversion efficiency is 38.6%,no obvious reverse transfaormation phenomenon is observed.The experimental results are consistent with the theory,and the feasibility of the 1.5?m self-OPO technology is verified.Under the premise of meeting the compact structure of the laser,a high repetition rate eye-safe 1.5?m laser output was obtained.
Keywords/Search Tags:Eye-safe of 1.5?m, Self-Optical Parametric Oscillator, High repetition rate, Nd:MgO:PPLN
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