用时域有限差分法求解Maxwell方程,数值研究了TM模在二维随机散射体系中传输,通过傅里叶变换得到不同几何参量和光学参量的散射体系内长寿命模的频谱.计算得出宽带脉冲源激励随机散射体系后,存在于随机体系中的长寿命模频谱以分立频率窗口的形式存在.建立了用以解释长寿命模以分立频率窗口存在的物理模型,该模型与数值研究结果吻合较好,论证了存在于随机散射体系中长寿命模的形成机制与传统光学谐振腔内冷腔模形成机制的相似性.

The transport of transverse magnetic (TM) mode in 2-dimension random scattering media is numerically investigated with finite-difference time-domain methods.And through Fourier transformation,the spectra of long-life localized modes in random media with different parameters are obtained.The spectra of long-life modes in random media are regularly grouped in distinct frequency windows after the broad-band excitation.A simple physical model is established to elucidate the phenomena of distinct frequency windows reasonablly.The research results indicate that the forming mechanism of long-life modes in random media is totally similar to that of cold modes in traditional standing-wave cavity.