Stabilization of Fiber Optic Brillouin Ring Laser and its Application to Active Fiber Optic Gyros

本研究的主要目的是建立光纤布里渊环形激光器的稳定激射方法，它是第三代光纤陀螺-主动式光纤陀螺的不可缺少的元件。在为期两年的研究过程中，首先研究了光纤谐振腔中布里渊散射产生激光的过程，详细考虑了光纤谐振腔中光的偏振特性，然后对光纤谐振腔中激光的偏振特性进行了分析，并对光纤谐振腔中激光的偏振特性进行了研究。对偏振轴旋转90 °的保偏光纤环形腔的特性分析表明，这种结构对稳定激光输出是有效的。由单偏振单模光纤构成的谐振腔具有稳定的激光输出。构建了前一种构型的实验装置，成功地验证了理论描述的特性。激光特性还受增益谱分布的影响，增益谱分布沿着增益介质的长的长度，即约10米的光纤。我们已经成功地分析了它们的影响，以澄清温度和/或张力分布沿着光纤上的激光特性的影响。此外，还研究了一种消除摇摆现象的方法和一种从陀螺输出信号中确定旋转方向的方法。提出并研究了一种稳定的掺铒光纤环形激光器结构和一种稳定的光折变光纤光栅无源环形谐振腔结构，为实现光纤布里渊激光陀螺奠定了基础，这也是本文研究的目的。

The main purpose of this research is to establish the ways to stabilize the lasing of a fiber optic Brillouin ring laser, which is an indispensable element of the third generation fiber optic gyroscope ; the active type fiber optic gyro. Moreover, performance deterioration factors and output-signal processing schemes are studied on the gyro system including the stabilized fiber optic Brillouin ring laser.During the two year research period, at first, the process to generate the laser light through the Brillouin scattering in the fiber resonator has been investigated, considering the polarization property of the lights in the resonator in detail. Analyzes of the characteristics of a polarization-maintaining fiber-ring-resonator with 90 degree polarization axis rotation at the splice have shown that this configuration is effective to stabilize the lasing. It has been also clarified that the resonator composed of a single-polarization single-mode fiber shows the stable lasing. The experimental setup of the former configuration has been constructed, which has successfully demonstrated the characteristics depicted in the theory. The lasing characteristics is also influenced by the gain spectrum distribution along the long length of the gain medium, that is, the fiber of about 10m. We have successfully analyzed their effect to clarify the influence of the temperature and/or the tension distribution along the fiber on the lasing characteristics. Moreover, a away to remove the rocking-in phenomena, by which the sensitivity drastically decreases, and a way to find the direction of the rotation from the gyro output have been studied. A stable ring laser configuration made of Er doped fiber and a stable passive ring resonator made of photo-refractive fiber grating have been also proposed and studied.Through these studies, the basic and important knowledge to realize the fiber optic Brillouin ring laser gyro have been obtained, which are the purpose of this study.