Scattering loss: Laser
An example of a complex layer structure where scattering loss is calculated for the Si waveguide core. Note that a fill_index is specified for the waveguide core, which is useful for structures formed by bonding. Also, a custom file name for the simulation is specified (“laser.eph”) instead of the default “emode.eph”.
The structure is taken roughly from: M. A. Tran, D. Huang, and J. E. Bowers, “Tutorial on narrow linewidth tunable semiconductor lasers using Si/III-V heterogeneous integration,” APL Photonics 4, 111101 (2019).
This code example is licensed under the BSD 3-Clause License.
import emodeconnection as emc
## Set simulation parameters
wavelength = 1550 # [nm] wavelength
dx, dy = 10, 5 # [nm] resolution
w_core = 1000 # [nm] waveguide core width
w_trench = 3000 # [nm] waveguide side trench width
h_core = 500 # [nm] waveguide core height
h_clad = 1000 # [nm] waveguide bottom clad
h_SL = 35 # [nm] superlattice height
h_n = 110 # [nm] n-contact height
h_SCH = 125 # [nm] SCH height
h_QW = 55 # [nm] quantum well height
h_uclad = 2000 # [nm] upper cladding height
window_width = w_core + w_trench*2 # [nm]
window_height = h_core + h_clad + h_SL + h_n + h_SCH*2 + h_QW + h_uclad # [nm]
num_modes = 1 # [-] number of modes
boundary = '00' # boundary condition
## Connect and initialize EMode
em = emc.EMode(simulation_name = 'laser') # custom file name instead of the default "emode.eph"
## Settings
em.settings(
wavelength = wavelength, x_resolution = dx, y_resolution = dy,
window_width = window_width, window_height = window_height,
num_modes = num_modes, background_refractive_index = 'SiO2',
boundary_condition = boundary)
## Draw shapes
em.shape(name = 'BOX', refractive_index = 'SiO2', height = h_clad)
em.shape(name = 'core', refractive_index = 'Si', height = h_core,
mask = w_core, etch = h_core*0.5, fill_refractive_index = 'Air',
roughness_rms = [5, 0.2], correlation_length = [100, 80])
em.shape(name = 'SL', refractive_index = 3.20, height = h_SL)
em.shape(name = 'n-contact', refractive_index = 3.17, height = h_n)
em.shape(name = 'SCH1', refractive_index = 3.43, height = h_SCH)
em.shape(name = 'QW', refractive_index = 3.41, height = h_QW)
em.shape(name = 'SCH2', refractive_index = 3.43, height = h_SCH)
em.shape(name = 'uclad', refractive_index = 3.17, height = h_uclad)
## Launch FDM solver
em.FDM()
## Display the effective indices, TE fractions, core confinement, and scattering loss
em.confinement(shape_list = 'core')
em.scattering(shape = 'core')
em.report()
## Display scattering loss details from the core
shape_core = em.get('shape_core')
sv = shape_core['scattering_vertical_edges']
sh = shape_core['scattering_horizontal_edges']
sT = shape_core['scattering_sum']
print('Scattering loss from all vertical edges: %0.1f dB/m' % sv)
print('Scattering loss from all horizontal edges: %0.1f dB/m' % sh)
print('Total scattering loss: %0.1f dB/m\n' % sT)
edges = shape_core['edges']
sa = shape_core['scattering_all_edges']
for kk in range(len(edges)):
print('From', edges[kk][0], 'to', edges[kk][1])
print(' scattering loss = %0.1f dB/m\n' % sa[0][kk])
## Plot the field and refractive index profiles
em.plot()
## Close EMode
em.close()
% Set simulation parameters
wavelength = 1550; % [nm] wavelength
dx = 10; dy = 5; % [nm] resolution
w_core = 1000; % [nm] waveguide core width
w_trench = 3000; % [nm] waveguide side trench width
h_core = 500; % [nm] waveguide core height
h_clad = 1000; % [nm] waveguide top and bottom clad
h_SL = 35; % [nm] superlattice height
h_n = 110; % [nm] n-contact height
h_SCH = 125; % [nm] SCH height
h_QW = 55; % [nm] quantum well height
h_uclad = 2000; % [nm] upper cladding height
window_width = w_core + w_trench*2; % [nm]
window_height = h_core + h_clad + h_SL + h_n + h_SCH*2 + h_QW + h_uclad; % [nm]
num_modes = 1; % [-] number of modes
boundary = '00'; % boundary condition
% Connect and initialize EMode
em = emodeconnection('simulation_name', 'laser'); % custom file name instead of the default 'emode.eph'
% Settings
em.settings( ...
'wavelength', wavelength, 'x_resolution', dx, 'y_resolution', dy, ...
'window_width', window_width, 'window_height', window_height, ...
'num_modes', num_modes, 'background_refractive_index', 'SiO2', ...
'boundary_condition', boundary);
% Draw shapes
em.shape('name', 'BOX', 'refractive_index', 'SiO2', 'height', h_clad);
em.shape('name', 'core', 'refractive_index', 'Si', 'height', h_core, ...
'mask', w_core, 'etch', h_core*0.5, 'fill_refractive_index', 'Air', ...
'roughness_rms', [5, 0.2], 'correlation_length', [100, 80]);
em.shape('name', 'SL', 'refractive_index', 3.20, 'height', h_SL);
em.shape('name', 'n-contact', 'refractive_index', 3.17, 'height', h_n);
em.shape('name', 'SCH1', 'refractive_index', 3.43, 'height', h_SCH);
em.shape('name', 'QW', 'refractive_index', 3.41, 'height', h_QW);
em.shape('name', 'SCH2', 'refractive_index', 3.43, 'height', h_SCH);
em.shape('name', 'uclad', 'refractive_index', 3.17, 'height', h_uclad);
% Launch FDM solver
em.FDM();
% Display the effective indices, TE fractions, core confinement, and scattering loss
em.confinement('shape_list', 'core');
em.scattering('shape', 'core');
em.report();
% Display scattering loss details from the core
shape_core = em.get('shape_core');
sv = shape_core.scattering_vertical_edges;
sh = shape_core.scattering_horizontal_edges;
sT = shape_core.scattering_sum;
fprintf('Scattering loss from all vertical edges: %0.1f dB/m\n', sv)
fprintf('Scattering loss from all horizontal edges: %0.1f dB/m\n', sh)
fprintf('Total scattering loss: %0.1f dB/m\n\n', sT)
edges = shape_core.edges;
sa = shape_core.scattering_all_edges;
for kk = 1:length(edges)
fprintf('From (%s) to (%s):', num2str(edges(kk,:,1)), num2str(edges(kk,:,2)))
fprintf(' scattering loss = %0.1f dB/m\n', sa(kk))
end
% Plot the field and refractive index profiles
em.plot();
% Close EMode
em.close();
Console output:
EMode 0.1.1 - email
Meshing... completed in 3.7 sec
Solving... completed in 11.6 sec
Wavelength: 1550.0 nm
Mode # n_eff TE % Loss (dB/m) core confinement core scattering (dB/m)
-------- -------- ------ ------------- ------------------ ------------------------
TE-0 3.291912 99.8 % 0.000 50.4 % 416.628
Exited EMode
Scattering loss from all vertical edges: 414.6 dB/m
Scattering loss from all horizontal edges: 2.0 dB/m
Total scattering loss: 416.6 dB/m
From [-500.0, 1250.0] to [-500.0, 1500.0]
scattering loss = 207.3 dB/m
From [500.0, 1500.0] to [500.0, 1250.0]
scattering loss = 207.3 dB/m
From [-500.0, 1500.0] to [500.0, 1500.0]
scattering loss = 0.5 dB/m
From [500.0, 1250.0] to [3500.0, 1250.0]
scattering loss = 0.2 dB/m
From [3500.0, 1000.0] to [-3500.0, 1000.0]
scattering loss = 1.1 dB/m
From [-3500.0, 1250.0] to [-500.0, 1250.0]
scattering loss = 0.2 dB/m
Figures:
