中文说明：
掺铒光纤放大器（EDFA）由一根长度为L的光纤组成，其核心均匀地掺杂着铒离子。这类离子可以被认为是简单的两能级系统，也就是说，它们只能有两种能量状态：1）基态；2）激发态。在适当的波长（通常为980nm或1480nm）下，一束强的“泵浦光”被传播到光纤的核心，以激发其离子。
English Description：
EDFA matlab coden Erbium Doped Fiber Amplifier (EDFA) consists of a piece of fiber of length L, whose core is uniformly doped with Erbium ions. Such ions can be thought of as simple two-level systems, i.e., they can have only two energy states: 1) a fundamental state and 2) an excited state. A strong ``pump laser light at the proper wavelength (usually 980 nm or 1480 nm) is propagated into the core of the fiber in order to excite its ions.