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Determines whether the fields in a cylindrical-coordinate simulation with m=±1 are purely real
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| import argparse | |
| import numpy as np | |
| import meep as mp | |
| def dipole_emission(res: float, dpml_r: float, dpml_z: float, s: float, | |
| m: int, fcen: float) -> float: | |
| """Computes the complex fields from an Er point source at r=z=0 in vacuum.""" | |
| cell_size = mp.Vector3(s+dpml_r,0,s+2*dpml_z) | |
| pml_layers = [ | |
| mp.PML(dpml_r, direction=mp.R), | |
| mp.PML(dpml_z, direction=mp.Z), | |
| ] | |
| sources = [ | |
| mp.Source( | |
| src=mp.CustomSource(src_func=lambda t: np.sin(2*np.pi*fcen*t)), | |
| center=mp.Vector3(), | |
| component=mp.Er, | |
| ), | |
| ] | |
| sim = mp.Simulation( | |
| resolution=res, | |
| cell_size=cell_size, | |
| dimensions=mp.CYLINDRICAL, | |
| m=m, | |
| sources=sources, | |
| boundary_layers=pml_layers, | |
| ) | |
| sim.run(until=40.6) | |
| er = sim.get_array( | |
| component=mp.Er, | |
| center=mp.Vector3(0.5*s,0,0), | |
| size=mp.Vector3(s,0,s), | |
| cmplx=True, | |
| ) | |
| return er | |
| if __name__ == '__main__': | |
| parser = argparse.ArgumentParser() | |
| parser.add_argument( | |
| '-res', | |
| type=float, | |
| default=50., | |
| help='resolution (default: 50.0)', | |
| ) | |
| parser.add_argument( | |
| '-dpml_r', | |
| type=float, | |
| default=1., | |
| help='PML thickness in r direction (default: 1.0)', | |
| ) | |
| parser.add_argument( | |
| '-dpml_z', | |
| type=float, | |
| default=1., | |
| help='PML thickness in z direction (default: 1.0)', | |
| ) | |
| parser.add_argument( | |
| '-s', | |
| type=float, | |
| default=5., | |
| help='thickess of non-PML region (default: 5.0)', | |
| ) | |
| args = parser.parse_args() | |
| er0 = dipole_emission(args.res, args.dpml_r, args.dpml_z, args.s, -1, +1.) | |
| er1 = dipole_emission(args.res, args.dpml_r, args.dpml_z, args.s, -1, -1.) | |
| er2 = dipole_emission(args.res, args.dpml_r, args.dpml_z, args.s, +1, +1.) | |
| er3 = dipole_emission(args.res, args.dpml_r, args.dpml_z, args.s, +1, -1.) | |
| def is_real(x): | |
| return np.all(np.conj(x) == x) | |
| # print out the first 20 elements of the Er arrays | |
| # for inspection of their imaginary parts | |
| print(f"er0:, {er0[:20]}") | |
| print(f"er1:, {er1[:20]}") | |
| print(f"er2:, {er2[:20]}") | |
| print(f"er3:, {er3[:20]}") | |
| print(f"real? er0: {is_real(er0)}, er1: {is_real(er1)}, " | |
| f"er2: {is_real(er2)}, er3: {is_real(er3)}") |
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output from running this script: