The dynamics of transient light transmission through a subwavelength slit can be intricate. Their complicated and diverse wave functions, such as beat-like, and their underlying novel physics are illuminated using a concept of step phasors and phase delay without involving nonlinearity. Step represents the change in amplitude for any non-steady function. Phase delay caused by roundtrip reflection within the slit is also critical. The two can trigger complex combinations of constructive and destructive interferences to manifest diverse consequences, which are frequently observed yet less understood. In addition to step broadening and alternative amplitude change, sinusoidal fields can be packaged together to form various wave packets, while a phase shift accumulates until steady state. Besides shedding light into new physics, our step phasor concept can also be generalized to study any form of incident light profiles and to clarify intriguing phenomena involving plasmonic metamaterials frequently occurring in nanophotonic simulations and experiments.

通过亚波长狭缝的瞬态光传输动力学可能很复杂。使用阶跃相量和相位延迟的概念阐明了它们复杂而多样的波动函数（如拍子样）及其潜在的新颖物理原理，而没有涉及非线性。阶跃表示任何非稳态函数的振幅变化。由狭缝内的往返反射引起的相位延迟也很关键。两者可以触发建设性和破坏性干扰的复杂组合，以表现出各种后果，而这种后果经常被观察到却很少被理解。除了阶跃加宽和可替代的幅度变化外，可以将正弦场打包在一起以形成各种波包，同时相移会累积到稳态。除了为新物理学注入光辉之外，