【作者】 付似愚；

【导师】 马力；

【作者基本信息】 南昌大学 ， 工程热物理， 2007， 硕士

【摘要】 “激光自混合”是指激光器的出射光被外部反射物反射或散射后，其中一部分光又被反馈回激光器的谐振腔。重新注入的激光与激光腔内的光混合，引起输出功率变化和频率变化，形成光学反馈效应。激光器的光学反馈效应会产生跳模，频率不稳定或者混沌，增加噪声，加宽谱线，一直被认为是严重影响激光光谱性质的干扰源。随着研究的深入，人们逐渐由消除光反馈的不利影响到主动利用光反馈现象进行物理量的测量，从而形成激光自混合干涉技术。结合自混合干涉原理和多普勒测速原理，将多普勒频移现象引入激光二极管。当来自被照射的物体表面的反射或散射光反馈回激光器时，把光强调制成为多普勒的频移信号。安装在激光器尾部的光电二极管，检测光学反馈生成的频移信号，确定物体的状态。研究He-Ne激光器和DFB激光器的自混合干涉效应。利用耦合波方程，推导出分布反馈激光器自混合干涉频率及增益变化的表达式。并考虑不同的参数对于自混合干涉的影响，进行了模拟计算与仿真分析。从分析的结果中可以得出，满足一定参数条件的分布反馈激光器比一般的F-P腔的半导体激光器对外部光反馈更加敏感。可以利用这一结论设计灵敏度更高的自混合干涉传感器。此类传感器不仅仅可用于测量固体的运动速度，也可以用来测量流体速度。被测流体中的颗粒散射的光反馈回激光腔并与腔内的光混合时，通过分析激光器的功率变化和频率变化，可以计算出流体的流动速度。此外，激光器的自混合干涉效应还可以用于测量能散射光的物体表面的温度。由于被测物体表面区域的温度影响，存在空气的折射率不均匀分布，会导致反馈光的光程产生变化，可以通过分析反馈回激光器腔内的散射光和腔内的光混合后的相位变化导致的功率和频率变化，计算得出被测物体表面的温度。更多还原

【Abstract】 "laser self-mixing" is that a portion of light emitted or scattered from a laser source by an external target is reflected or scattered back into the laser cavity.The reinjected laser mixes with the light from the laser cavity and changes of the power and frequency,then forms the optical feedback effect.The optical feedback effect of the lasers with the defect of changing model,frequency instability or chaos, noise, widening spectra,is regard as the disturbing original which affects the spectra of the laser.With the further research,the optical feedback phenomena is changed to be used to metrology from the affect of eliminating light feedback,thus generates the self-mixing interference technology.Self-mixing interference in a LD occurs when a portion of light emitted from the LD is reflected by an object and coupled into the LD cavity.The reentered light mixes with the original light in the LD cavity and changes the output power and spectra of the laser.The resultant Doppler shift was accepted by PD.The Self-mixing interference effect can be used in metrology and sensing technology,such as velocity, displacement,ranging and vibration measurement.Research self-mixing interference in He-Ne lasers and DFB lasers,the general expression of the threshold gain and frequency in the DFB lasers was deduced by using the coupled wave function.Numerical simulations indicate that,for specific coupling coefficient and cavity length value,the DFB lasers are more sensitive to optical feedback than the Fabry-Perot semiconductor laser.These results show that high-accuracy self-mixing sensors can be obtained by using the DFB lasers.The high-accuracy self-mixing sensors can be used to measure the liquid velocity.When a small fraction of the light back-reflected or back-scattered by the liquid re-enters into the laser cavity,the output gain change in the cavity will be caused.And,the high-accuracy self-mixing sensors can be used to measure the target temperature.The target temperature change the air refractive index.The frequency shift is changed by the air refractive index.The temperature value is extracted by the signal processing.更多还原