oblique-source.py

import meep as mp
import numpy as np
import matplotlib.pyplot as plt

resolution = 50 # pixels/μm

cell_size = mp.Vector3(14,14)

pml_layers = [mp.PML(thickness=2)]

# rotation angle (in degrees) of waveguide, counter clockwise (CCW) around z-axis
rot_angle = np.radians(20)

w = 1.0 # width of waveguide

geometry = [mp.Block(center=mp.Vector3(),
                     size=mp.Vector3(mp.inf,w,mp.inf),
                     e1=mp.Vector3(1).rotate(mp.Vector3(z=1), rot_angle),
                     e2=mp.Vector3(y=1).rotate(mp.Vector3(z=1), rot_angle),
                     material=mp.Medium(epsilon=12))]

fsrc = 0.15 # frequency of eigenmode or constant-amplitude source
kx = 0.4    # initial guess for wavevector in x-direction of eigenmode
bnum = 1    # band number of eigenmode

kpoint = mp.Vector3(kx).rotate(mp.Vector3(z=1), rot_angle)

compute_flux = True # compute flux (True) or plot the field profile (False)

eig_src = True # eigenmode (True) or constant-amplitude (False) source

if eig_src:
    sources = [mp.EigenModeSource(src=mp.GaussianSource(fsrc,fwidth=0.2*fsrc) if compute_flux else mp.ContinuousSource(fsrc),
                                  center=mp.Vector3(),
                                  size=mp.Vector3(y=3*w),
                                  direction=mp.NO_DIRECTION,
                                  eig_kpoint=kpoint,
                                  eig_band=bnum,
                                  eig_parity=mp.EVEN_Y+mp.ODD_Z if rot_angle == 0 else mp.ODD_Z,
                                  eig_match_freq=True)]
else:
    sources = [mp.Source(src=mp.GaussianSource(fsrc,fwidth=0.2*fsrc) if compute_flux else mp.ContinuousSource(fsrc),
                         center=mp.Vector3(),
                         size=mp.Vector3(y=3*w),
                         component=mp.Ez)]

sim = mp.Simulation(cell_size=cell_size,
                    resolution=resolution,
                    boundary_layers=pml_layers,
                    sources=sources,
                    geometry=geometry,
                    symmetries=[mp.Mirror(mp.Y)] if rot_angle == 0 else [])

if compute_flux:
    tran = sim.add_flux(fsrc, 0, 1, mp.FluxRegion(center=mp.Vector3(x=5), size=mp.Vector3(y=14)))
    sim.run(until_after_sources=50)
    res = sim.get_eigenmode_coefficients(tran,
                                         [1],
                                         eig_parity=mp.EVEN_Y+mp.ODD_Z if rot_angle == 0 else mp.ODD_Z,
                                         direction=mp.NO_DIRECTION,
                                         kpoint_func=lambda f,n: kpoint)
    print("flux:, {:.6f}, {:.6f}".format(mp.get_fluxes(tran)[0],abs(res.alpha[0,0,0])**2))
else:
    sim.run(until=100)
    sim.plot2D(output_plane=mp.Volume(center=mp.Vector3(), size=mp.Vector3(10,10)),
               fields=mp.Ez,
               field_parameters={'alpha':0.9})
    plt.show()