FDTD绘制场强随波长变化的FDTDscript

以下是一个简单的FDTDscript，用于模拟电磁波在二维空间中的传播，并绘制随波长变化的场强分布。

import numpy as np
import matplotlib.pyplot as plt

# Parameters
c = 3e8  # speed of light in vacuum
dx = 1e-6  # spatial step size
dt = dx/c  # time step size
lambda_0 = 500e-9  # central wavelength
n = 1.5  # refractive index of the medium
Lx = 20e-6  # domain length in x-direction
Ly = 20e-6  # domain length in y-direction
M = int(Lx/dx)  # number of spatial grids in x-direction
N = int(Ly/dx)  # number of spatial grids in y-direction
T = 2000  # number of time steps
lambda_list = np.linspace(400e-9, 700e-9, 61)  # wavelength list

# Initialization
Ez = np.zeros((M, N))
Hy = np.zeros((M, N))

# Main loop
for t in range(T):
    # Update Hy
    for i in range(M-1):
        for j in range(N-1):
            Hy[i, j] -= (Ez[i+1, j] - Ez[i, j])/dx
    
    # Update Ez
    for i in range(1, M-1):
        for j in range(1, N-1):
            Ez[i, j] += (Hy[i, j] - Hy[i-1, j])/dx
            Ez[i, j] /= n
    
    # Source
    Ez[int(M/2), int(N/2)] += np.sin(2*np.pi*c*t*dt/lambda_0)
    
    # Boundary conditions
    Ez[0, :] = 0
    Ez[M-1, :] = 0
    Ez[:, 0] = 0
    Ez[:, N-1] = 0
    
    # Plot the field profile at the central point
    if t % 100 == 0:
        plt.plot(lambda_list, np.abs(Ez[int(M/2), int(N/2)]), 'o-')
        plt.xlabel('wavelength (m)')
        plt.ylabel('electric field amplitude')
        plt.show()

该脚本使用了FDTD方法模拟电磁波在二维空间中的传播，并在每个时间步长绘制了场强随波长变化的曲线。可以通过修改参数来调整模拟的精度和范围，以及绘制的曲线的数量和分辨率。