Wang Heming, Lai Yu-Hung, Yuan Zhiquan, Suh Myoung-Gyun, Vahala Kerry
T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA, 91125, USA.
OEwaves Inc., 465 North Halstead Street, Suite 140, Pasadena, CA, 91107, USA.
Nat Commun. 2020 Mar 31;11(1):1610. doi: 10.1038/s41467-020-15341-6.
Exceptional points are singularities of open systems, and among their many remarkable properties, they provide a way to enhance the responsivity of sensors. Here we show that the improved responsivity of a laser gyroscope caused by operation near an exceptional point is precisely compensated by increasing laser noise. The noise, of fundamental origin, is enhanced because the laser mode spectrum loses the oft-assumed property of orthogonality. This occurs as system eigenvectors coalesce near the exceptional point and a bi-orthogonal analysis confirms experimental observations. While the results do not preclude other possible advantages of the exceptional-point-enhanced responsivity, they do show that the fundamental sensitivity limit of the gyroscope is not improved through this form of operation. Besides being important to the physics of microcavities and non-Hermitian photonics, these results help clarify fundamental sensitivity limits in a specific class of exceptional-point sensor.
例外点是开放系统的奇点，在其众多显著特性中，它们提供了一种提高传感器响应度的方法。在此我们表明，由在例外点附近运行引起的激光陀螺仪响应度的提高，会因激光噪声增加而被精确补偿。这种源于基本原理的噪声会增强，因为激光模式光谱失去了通常所假定的正交性。当系统本征向量在例外点附近合并时就会出现这种情况，并且双正交分析证实了实验观察结果。虽然这些结果并不排除例外点增强响应度的其他可能优势，但它们确实表明，通过这种运行形式，陀螺仪的基本灵敏度极限并未得到改善。除了对微腔和非厄米光子学的物理学很重要之外，这些结果有助于阐明特定类别的例外点传感器中的基本灵敏度极限。
