从理论上探讨了回音壁模式的传输谱线形状与激光扫描速度的关系,以及激光扫描速度对测量微腔Q值的影响.研究表明,在较低的激光扫描速度下,传输谱线为洛伦兹线型;但随着激光扫描速度的增大,会出现不同程度的振铃现象,并且振铃现象的明显程度还与耦合情况有关.结果还表明采用激光慢速扫频结合洛伦兹拟合方法得到的Q值是可靠的.
The relationship between the shape of the transmission spectrum of the whispering gallery mode microresonator and the laser sweeping speed as well as the influence of the laser sweeping speed on the measurement of Q factor is theoretically investigated. It is shown that the transmission will have a Lorentz shape if the laser sweeping speed is low and a ringing phenomenon will be observed if the laser sweeping speed is fast enough, where the ringing phenomenon is also related to the coupling condition between the microresonator and the fiber taper. It is also shown that the method using a slow laser sweeping speed and Lorentz fitting to measure Q factors is reliable