基于声光调Q的脉冲光纤激光器研究

发布时间：2018-05-08 09:51

本文选题：光纤激光器 + 调Q技术　；参考：《吉林大学》2017年硕士论文

【摘要】：调Q脉冲光纤激光器可以将激光器谐振腔存储的能量在极短时间内释放出来,形成脉冲宽度在ns量级、峰值功率在KW量级的调Q激光脉冲输出。结合主振荡功率放大方案,其平均输出功率可达几百W,在激光加工、激光雷达、光时域反射计、非线性频率变换等方面有着广泛应用。声光调Q作为调Q脉冲光纤激光器的一种实现方式,具有输出调Q激光脉冲性能稳定、可控性好等优点,获得了广泛关注。本文搭建了非对称腔、对称腔两种结构的声光调Q脉冲光纤激光器实验系统,对输出调Q激光脉冲的重频、平滑度、输出功率、脉宽等特性进行了较为深入的研究,分析了泵浦功率、声光Q开关重复频率对输出调Q激光脉冲重频的影响,优化了输出调Q激光脉冲中的多峰现象,获得了平滑脉冲输出。所做具体工作如下:首先,介绍了调Q技术原理以及常用的调Q实现方法,理论分析了泵浦功率、谐振腔处于低Q值的时间、腔长等因素对调Q脉冲光纤激光器输出特性的影响。详细介绍了声光调Q脉冲光纤激光器的工作原理。其次,搭建了非对称腔和对称腔两种结构的声光调Q脉冲光纤激光器实验系统,研究了声光Q开关开启时间为5μs、重复频率在10KHz-80KHz范围内变化时,输出调Q激光脉冲的特性。非对称腔结构中采用后向泵浦方式,获得的最大输出功率为1.61W,最窄脉宽为61ns。对称腔结构中采用半导体激光器单独泵浦、半导体模块单独泵浦、半导体激光器+半导体模块对称泵浦三种泵浦方式,在对称泵浦时,获得最大输出功率为0.59W,最窄脉宽为58ns。然后,论文中还着重在非对称腔和对称腔两种结构下研究了输出调Q激光脉冲的重频特性和平滑特性。无论是在非对称腔结构还是对称腔结构中,泵浦功率、声光Q开关重复频率只有在一定的范围内,输出调Q激光脉冲重频才能与声光Q开关重复频率一致。当泵浦功率固定时,随着声光Q开关重复频率的增大,输出调Q激光脉冲重频依次为声光Q开关重复频率、声光Q开关重复频率的1/2、声光Q开关重复频率的1/3;当声光Q开关重复频率固定时,随着泵浦功率的减小,输出调Q激光脉冲重频依次为声光Q开关重复频率、声光Q开关重复频率的1/2、声光Q开关重复频率的1/3。在非对称腔结构中,通过增大泵浦功率、降低声光Q开关重复频率、减小声光Q开关开启时间的方法可以减少输出调Q激光脉冲中多峰的个数、优化脉冲波形,并且利用此种方法,在泵浦功率为8W,声光Q开关重复频率为10KHz、开启时间为230ns时,获得了脉宽为38ns的平滑调Q激光脉冲输出。在对称腔结构中,通过对称泵浦的方式,获得了重频在10KHz-80KHz范围内可调的平滑调Q激光脉冲输出。本文在非对称腔、对称腔两种腔结构下研究了声光调Q脉冲光纤激光器的输出特性,并对输出调Q激光脉冲的重频特性和平滑特性进行了着重研究,最终获得了重频为10KHz-80KHz的平滑调Q激光脉冲输出。
[Abstract]:Q-switched pulse fiber laser can release the energy stored in the resonator in a very short time to form Q-switched laser pulse with pulse width of ns and peak power of KW. Combined with the main oscillation power amplification scheme, the average output power can reach several hundred ws. it is widely used in laser processing, lidar, optical time domain reflectometer, nonlinear frequency conversion and so on. Acousto-optic Q-switching as a realization method of Q-switched pulse fiber laser has been paid more and more attention because of its stable performance and good controllability. In this paper, an experimental system of acousto-optic Q-switched pulse fiber laser with asymmetric cavity and symmetrical cavity is built. The characteristics of output Q-switched laser pulse, such as repetition frequency, smoothness, output power and pulse width, are studied deeply. The effects of pump power and repetition rate of acousto-optic Q-switch on the repetition rate of output Q-switched laser pulse are analyzed. The multi-peak phenomenon in the output Q-switched laser pulse is optimized and the smooth pulse output is obtained. The specific work is as follows: firstly, the principle of Q-switched technology and the commonly used Q-switching methods are introduced. The pump power and the time of low Q value of the resonator are analyzed theoretically. The effect of cavity length on the output characteristics of Q-switched pulsed fiber laser. The principle of acoustooptic Q-switched pulsed fiber laser is introduced in detail. Secondly, the experimental system of acousto-optic Q-switched pulse fiber laser with asymmetric cavity and symmetrical cavity is built. The characteristics of Q-switched laser pulse are studied when the switching time of acousto-optic Q-switch is 5 渭 s and the repetition rate is in the range of 10KHz-80KHz. The maximum output power is 1.61W and the narrowest pulse width is 61ns. In the symmetrical cavity structure, the semiconductor laser is used to pump alone, the semiconductor module to pump alone, and the semiconductor module to pump symmetrically. The maximum output power is 0.59 W and the narrowest pulse width is 58 ns. Then, the repetition and smoothing characteristics of the output Q-switched laser pulses are also studied in the asymmetric cavity and the symmetric cavity. The repetition rate of the output Q-switched laser pulse can be consistent with that of the acousto-optic Q-switch if the pump power and the repetition rate of the Q-switching switch are only within a certain range in the asymmetric cavity structure or the symmetrical cavity structure. When the pump power is fixed, the repetition frequency of the output Q-switched laser pulse is in turn the acousto-optic Q-switched repetition frequency with the increase of the acousto-optic Q-switch repetition frequency. The repetition rate of acousto-optic Q switch is 1 / 2 and that of acousto-optic Q switch is 1 / 3. When the repetition rate of acousto-optic Q switch is fixed, with the decrease of pump power, the repetition frequency of output Q-switched laser pulse is in turn acousto-optic Q-switched repetition frequency. The repetition rate of acoustooptic Q switch is 1 / 2, and that of acoustooptic Q switch is 1 / 3. In asymmetric cavity structure, by increasing pump power, decreasing the repetition frequency of acousto-optic Q switch and decreasing the opening time of acousto-optic Q-switch, the number of multi-peaks in the output Q-switched laser pulse can be reduced, and the pulse waveform can be optimized. By using this method, when the pump power is 8 W, the repetition rate of acousto-optic Q switch is 10 kHz and the opening time is 230ns, the smooth Q-switched laser pulse with pulse width of 38ns is obtained. In the symmetrical cavity structure, a smooth Q-switched laser pulse output with adjustable repetition frequency in the 10KHz-80KHz range is obtained by symmetric pumping. In this paper, the output characteristics of acousto-optic Q-switched pulse fiber laser are studied under two kinds of cavity structures: asymmetric cavity and symmetric cavity, and the repetition and smoothing characteristics of the output Q-switched laser pulse are studied emphatically. Finally, a smooth Q-switched laser pulse with repetition frequency of 10KHz-80KHz is obtained.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248

【相似文献】