Department of Applied Physics, Stanford University, Stanford, California 94305, USA.
Ginzton Laboratory and Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA.
Phys Rev Lett. 2022 Jun 24;128(25):256101. doi: 10.1103/PhysRevLett.128.256101.
Reciprocity is a fundamental symmetry of Maxwell's equations. It is known that reciprocity imposes constraints on transmission, absorption, and emission. Here, we reveal reciprocity constraints on reflection. We determine the sets of all attainable reflection coefficients of n-port scattering matrices with prescribed singular values, both with and without assuming reciprocity. Their difference establishes reciprocity constraints and nonreciprocal behaviors. As an application, we examine the conditions for all-zero reflections. Our results deepen the understanding of reciprocity in optics.
互易性是麦克斯韦方程组的基本对称性。众所周知，互易性对传输、吸收和发射施加了约束。在这里，我们揭示了反射的互易性约束。我们确定了具有规定奇异值的 n 端口散射矩阵的所有可实现反射系数的集合，同时考虑和不考虑互易性。它们的差异建立了互易性约束和非互易性行为。作为应用，我们研究了全零反射的条件。我们的结果深化了对光学互易性的理解。
