def add_bezier_to(self,
final_coordinates,
final_angle,
bend_strength,
width=None,
**kwargs):
try:
bs1, bs2 = float(bend_strength[0]), float(bend_strength[1])
except (KeyError, TypeError):
bs1 = bs2 = float(bend_strength)
final_port = Port(final_coordinates, final_angle, self.width)
p0 = (0, 0)
p1 = self._current_port.longitudinal_offset(
bs1).origin - self._current_port.origin
p2 = final_port.longitudinal_offset(
-bs2).origin - self._current_port.origin
p3 = final_coordinates - self._current_port.origin
tmp_wg = Waveguide.make_at_port(
self._current_port.copy().set_port_properties(angle=0))
tmp_wg.add_cubic_bezier_path(p0, p1, p2, p3, width=width, **kwargs)
self._segments.append(
(self._current_port.copy(), tmp_wg.get_shapely_object(),
tmp_wg.get_shapely_outline(), tmp_wg.length,
tmp_wg.center_coordinates))
self._current_port = tmp_wg.current_port
return self
class RingResonator:
"""
A simple Ring / Race track resonator.
This part implements a super simple ring resonator with optional race tracks. Several
helper functions are available to calculate points and ports of interest. The width of the
feeding waveguide and the ring waveguide may differ.
:param origin: Origin of the resonator, which is the start of the input waveguide.
:param angle: Angle of the input waveguide.
:param width: Width of the angle waveguide.
:param gap: Gap between ring and waveguide. If positive, the ring will be on the left, and on the right side for
negative gap values. Can also be a 2-tuple, if input and output gap should be different.
:param radius: Radius of the bends.
:param race_length: Length of the race track. Defaults to zero.
:param draw_opposite_side_wg: If True, draw the opposing waveguides, (a.k.a. drop ports.)
:param res_wg_width: Width of the resonator waveguide. If None, the width of the input waveguide is assumend.
:param n_points: Number of points used per quarter circle. If None, it uses the bend default.
:param straight_feeding: Add straight connections on both sides of the resonator.
:param vertical_race_length: Length of a vertical race track section. Defaults to zero.
"""
def __init__(self,
origin,
angle,
width,
gap,
radius,
race_length=0,
draw_opposite_side_wg=False,
res_wg_width=None,
n_points=None,
straight_feeding=False,
vertical_race_length=0):
assert race_length >= 0, 'The race track length must not be negative'
assert vertical_race_length >= 0, 'The vertical race track length must not be negative'
assert radius > 0, 'The bend radius must not be negative'
# Let's directly create a port object. This simplifies later creation of the geometry
# as well as checking the user parameters while creating the port.
self._origin_port = Port(origin, angle, width)
# Ring gap
try:
self.gap, self.opposite_gap = gap
if np.sign(self.gap) != np.sign(self.opposite_gap):
raise ValueError
except TypeError:
self.gap = gap
self.opposite_gap = gap
# Remember all the other stuff we got
self.radius = radius
self.race_length = race_length
self.res_wg_width = res_wg_width if res_wg_width else width
self.points = n_points
self.draw_opposite_side_wg = draw_opposite_side_wg
self.straight_feeding = straight_feeding
self.vertical_race_length = vertical_race_length
@classmethod
def make_at_port(cls, port, gap, radius, **kwargs):
default_port_param = dict(port.get_parameters())
default_port_param.update(kwargs)
del default_port_param['origin']
del default_port_param['angle']
del default_port_param['width']
return cls(port.origin, port.angle, port.width, gap, radius,
**default_port_param)
###
# Let's allow the user to change the values
# hidden in _origin_port. Hence the internal use
# of a Port is transparent.
@property
def origin(self):
return self._origin_port.origin
@origin.setter
def origin(self, origin):
self._origin_port.origin = origin
@property
def angle(self):
return self._origin_port.angle
@angle.setter
def angle(self, angle):
self._origin_port.angle = angle
@property
def width(self):
return self._origin_port.width
@width.setter
def width(self, width):
self._origin_port.width = width
####
# Now, lets get to the functions the user is actually
# interested in.
@property
def port(self):
offset = self.race_length + 2 * self.radius if self.straight_feeding else 0
return self._origin_port.longitudinal_offset(offset)
out_port = port
@property
def opposite_side_port_out(self):
return self.port.parallel_offset(
np.copysign(2 * self.radius +
self.vertical_race_length, self.opposite_gap) +
self._offset + self._offset_opposite)
@property
def opposite_side_port_in(self):
return self._origin_port.parallel_offset(
np.copysign(2 * self.radius +
self.vertical_race_length, self.opposite_gap) +
self._offset + self._offset_opposite).inverted_direction
# Conventional naming of ports
@property
def in_port(self):
return self._origin_port.inverted_direction
@property
def add_port(self):
return self.opposite_side_port_out
@property
def drop_port(self):
return self.opposite_side_port_in
@property
def through_port(self):
return self.port
@property
def center_coordinates(self):
return self._origin_port.longitudinal_offset(
self.race_length / 2.).parallel_offset(
self._offset +
np.copysign(self.radius +
0.5 * self.vertical_race_length, self.gap)).origin
@property
def _offset(self):
return math.copysign(
abs(self.gap) + (self.width + self.res_wg_width) / 2., self.gap)
@property
def _offset_opposite(self):
return math.copysign(
abs(self.opposite_gap) + (self.width + self.res_wg_width) / 2.,
self.opposite_gap)
@property
def circumference(self):
return 2 * np.pi * self.radius + 2 * self.race_length
def get_shapely_object(self):
wg = Waveguide.make_at_port(self._origin_port)
opposite_wg = Waveguide.make_at_port(
self.opposite_side_port_in.inverted_direction)
if self.straight_feeding:
wg.add_straight_segment(self.radius)
if self.draw_opposite_side_wg:
opposite_wg.add_straight_segment(self.radius)
ring_port = wg.current_port.parallel_offset(self._offset)
ring_port.width = self.res_wg_width
ring = Waveguide.make_at_port(ring_port)
if self.race_length:
wg.add_straight_segment(self.race_length)
if self.draw_opposite_side_wg:
opposite_wg.add_straight_segment(self.race_length)
if self.straight_feeding:
wg.add_straight_segment(self.radius)
if self.draw_opposite_side_wg:
opposite_wg.add_straight_segment(self.radius)
# Build the ring
bend_angle = math.copysign(0.5 * np.pi, self.gap)
if self.race_length:
ring.add_straight_segment(self.race_length)
ring.add_bend(bend_angle, self.radius, n_points=self.points)
if self.vertical_race_length:
ring.add_straight_segment(self.vertical_race_length)
ring.add_bend(bend_angle, self.radius, n_points=self.points)
if self.race_length:
ring.add_straight_segment(self.race_length)
ring.add_bend(bend_angle, self.radius, n_points=self.points)
if self.vertical_race_length:
ring.add_straight_segment(self.vertical_race_length)
ring.add_bend(bend_angle, self.radius, n_points=self.points)
return geometric_union([ring, wg, opposite_wg])
class Waveguide:
def __init__(self, origin, angle, width):
self._current_port = Port(origin, angle, width)
self._in_port = self._current_port.inverted_direction.copy()
self._segments = list()
@classmethod
def make_at_port(cls, port, **kargs):
port_param = port.copy()
port_param.set_port_properties(**kargs)
return cls(**port_param.get_parameters())
@property
def x(self):
return self._current_port.origin[0]
@property
def y(self):
return self._current_port.origin[1]
@property
def origin(self):
return self._current_port.origin
@property
def angle(self):
return self._current_port.angle
@property
def width(self):
return self._current_port.width
@width.setter
def width(self, width):
self._current_port.width = width
@property
def current_port(self):
return self._current_port.copy()
# Add alias for current port
port = current_port
@property
def in_port(self):
return self._in_port.copy()
@property
def length(self):
return sum((length for port, obj, outline, length, center_coordinates
in self._segments))
@property
def length_last_segment(self):
if not len(self._segments):
return 0
return self._segments[-1][3]
@property
def center_coordinates(self):
return np.concatenate([
center_coordinates for port, obj, outline, length,
center_coordinates in self._segments
])
def get_shapely_object(self):
"""
Get a shapely object which forms this path.
"""
return shapely.ops.cascaded_union([
obj for port, obj, outline, length, center_coordinates in
self._segments
])
def get_shapely_outline(self):
"""
Get a shapely object which forms the outline of the path.
"""
return shapely.ops.cascaded_union([
outline for port, obj, outline, length, center_coordinates in
self._segments
])
def get_segments(self):
"""
Returns the list of tuples, containing their ports and shapely objects.
"""
return [(port.copy(), obj, length) for port, obj, outline, length,
center_coordinates in self._segments]
def add_straight_segment(self, length, final_width=None, **kwargs):
self._current_port.set_port_properties(**kwargs)
final_width = final_width if final_width is not None else self.width
if not np.isclose(length, 0):
assert length >= 0, 'Length of straight segment must not be negative'
self.add_parameterized_path(path=lambda t: [t * length, 0],
path_derivative=lambda t: [1, 0],
width=lambda t: np.array(self.width) *
(1 - t) + np.array(final_width) * t,
sample_points=2,
sample_distance=0)
return self
def add_arc(self,
final_angle,
radius,
final_width=None,
n_points=128,
shortest=True,
**kwargs):
delta = final_angle - self.angle
if not np.isclose(normalize_phase(delta), 0):
if shortest:
delta = normalize_phase(delta)
self.add_bend(delta, radius, final_width, n_points, **kwargs)
return self
def add_bend(self,
angle,
radius,
final_width=None,
n_points=128,
**kwargs):
# If number of points is None, default to 128
n_points = n_points if n_points else 128
self._current_port.set_port_properties(**kwargs)
sample_points = max(int(abs(angle) / (np.pi / 2) * n_points), 2)
final_width = final_width if final_width is not None else self.width
angle = normalize_phase(
angle, zero_to_two_pi=True) - (0 if angle > 0 else 2 * np.pi)
self.add_parameterized_path(
path=lambda t: [
radius * np.sin(abs(angle) * t),
np.sign(angle) * -radius * (np.cos(angle * t) - 1)
],
path_function_supports_numpy=True,
path_derivative=lambda t: [
radius * np.cos(abs(angle) * t) * abs(angle),
np.sign(angle) * radius * (np.sin(angle * t) * angle)
],
width=lambda t: np.outer(1 - t, np.array(self.width)) + np.outer(
t, np.array(final_width)),
width_function_supports_numpy=True,
sample_points=sample_points,
sample_distance=0)
return self
def add_parameterized_path(self,
path,
width=None,
sample_distance=0.50,
sample_points=100,
path_derivative=None,
path_function_supports_numpy=False,
width_function_supports_numpy=False):
"""
Generate a parameterized path.
The path coordinate system is the origin and rotation of the current path. So if you want to continue your path
start at (0, 0) in y-direction.
Note, that path is either a list of (x,y) coordinate tuples or a callable function which takes one float
parameter between 0 and 1. If you use a parameterized function, its first derivative must be continuous.
When using a list of coordinates, these points will be connected by straight lines. They must be sufficiently
close together to simulate a first derivative continuous path.
This function will try to space the final points of the curve equidistantly. To achieve this, it will first
sample the function and find its first derivative. Afterwards it can calculate the cumulative sum of the length
of the first derivative. This allows to sample the function nearly equidistantly in a second step. This
approach might be wasteful for paths like (x**2, y). You can suppress resampling for length by passing zero or
none as sample_distance parameter.
The width of the generated waveguide may be constant when passing a number, or variable along the path
when passing an array or a callable function, using the same parameter as the path.
For generating slot/coplanar/... waveguides, start with a `Port` which has an array of the form
`[rail_width_1, gap_width_1, rail_width_2, ...]` set as `width` and which defines the width of each
rail and the gaps between the rails. This array is also allowed to end with a gap_width for positioning the
rails asymmetrically to the path which can be useful e.g. for strip-to-slot mode converters.
Note, that your final direction of the path might not be what you expected. This is caused by the numerical
procedure which generates numerical errors when calculating the first derivative. You can either append another
arc to the waveguide to get to you a correct angle or you can also supply a function which is the algebraic
first derivative. The returned vector is not required to be normed.
By default, for each parameter point t, the parameterized functions are call. You will notice that this is
rather slow. To achieve the best performance, write your functions in such a way, that they can handle a
numpy array as parameter *t*. Once the *path_function_supports_numpy* option is set to True, the function will
be called only once, speeding up the calculation considerable.
:param path:
:param width:
:param sample_distance:
:param sample_points:
:param path_derivative:
:param path_function_supports_numpy:
:param width_function_supports_numpy:
"""
if callable(path):
presample_t = np.linspace(0, 1, sample_points)
if path_function_supports_numpy:
presample_coordinates = np.array(path(presample_t)).T
else:
presample_coordinates = np.array(
[path(x) for x in presample_t])
if sample_distance:
# # Calculate the derivative
# if path_derivative:
# assert callable(path_derivative), 'The derivative of the path function must be callable'
# presample_coordinates_d1 = np.array([path_derivative(x) for x in presample_t[:-1]])
# else:
# presample_coordinates_d1 = np.diff(presample_coordinates, axis=0)
presample_coordinates_d1 = np.diff(presample_coordinates,
axis=0)
presample_coordinates_d1_norm = np.linalg.norm(
presample_coordinates_d1, axis=1)
presample_coordinates_d1__cum_norm = np.insert(
np.cumsum(presample_coordinates_d1_norm), 0, 0)
lengths = np.linspace(
presample_coordinates_d1__cum_norm[0],
presample_coordinates_d1__cum_norm[-1],
int(presample_coordinates_d1__cum_norm[-1] /
sample_distance))
# First get the spline representation. This is needed since we manipulate these directly for roots
# finding.
spline_rep = scipy.interpolate.splrep(
presample_t, presample_coordinates_d1__cum_norm, s=0)
def find_y(y):
interp_result = scipy.interpolate.sproot(
(spline_rep[0], spline_rep[1] - y, spline_rep[2]),
mest=1)
return interp_result[0] if len(interp_result) else None
# We need a small hack here and exclude lengths[0]==0 since it finds no root there
sample_t = np.array([
0,
] + [find_y(length) for length in lengths[1:-1]] + [
1,
])
if path_function_supports_numpy:
sample_coordinates = np.array(path(sample_t)).T
else:
sample_coordinates = np.array([path(x) for x in sample_t])
else:
sample_coordinates = presample_coordinates
sample_t = presample_t
else:
# If we do not have a sample function, we need to "invent a sampling parameter"
sample_coordinates = np.array(path)
sample_t = np.linspace(0, 1, sample_coordinates.shape[0])
rotation_matrix = np.array(((np.cos(self._current_port.angle),
-np.sin(self._current_port.angle)),
(np.sin(self._current_port.angle),
np.cos(self._current_port.angle))))
sample_coordinates = self._current_port.origin + np.einsum(
'ij,kj->ki', rotation_matrix, sample_coordinates)
# Calculate the derivative
if callable(path_derivative):
if path_function_supports_numpy:
sample_coordinates_d1 = np.array(path_derivative(sample_t)).T
else:
sample_coordinates_d1 = np.array(
[path_derivative(x) for x in sample_t])
sample_coordinates_d1 = np.einsum('ij,kj->ki', rotation_matrix,
sample_coordinates_d1)
else:
if path_derivative is None:
sample_coordinates_d1 = np.vstack(
(rotation_matrix[:, 0], np.diff(sample_coordinates,
axis=0)))
else:
sample_coordinates_d1 = np.array(path_derivative)
sample_coordinates_d1 = np.einsum('ij,kj->ki', rotation_matrix,
sample_coordinates_d1)
sample_coordinates_d1_norm = np.linalg.norm(sample_coordinates_d1,
axis=1)
sample_coordinates_d1_normed = sample_coordinates_d1 / sample_coordinates_d1_norm[:,
None]
# Find the orthogonal vectors to the derivative
sample_coordinates_d1_normed_ortho = np.vstack(
(sample_coordinates_d1_normed[:, 1],
-sample_coordinates_d1_normed[:, 0])).T
# Calculate the width of the waveguide at the given positions
if callable(width):
if width_function_supports_numpy:
sample_width = width(sample_t)
else:
sample_width = np.array([width(x) for x in sample_t])
if sample_width.ndim == 1: # -> width returned a scalar for each x
sample_width = sample_width[..., np.newaxis]
else:
if width is None:
sample_width = np.atleast_1d(self._current_port.width)
sample_width = sample_width[
np.newaxis, ...] # width constant -> new axis along path
else:
sample_width = np.atleast_1d(width)
if sample_width.ndim == 1: # -> width is a scalar for each x
sample_width = sample_width[..., np.newaxis]
# Now we have everything to calculate the polygon
polygons = []
half_width = np.sum(sample_width, axis=-1) / 2
for i in range((sample_width.shape[-1] + 1) // 2):
start = np.sum(sample_width[:, :(2 * i)], axis=-1) - half_width
stop = start + sample_width[:, 2 * i]
poly_path_1 = sample_coordinates + start[
..., None] * sample_coordinates_d1_normed_ortho
poly_path_2 = sample_coordinates + stop[
..., None] * sample_coordinates_d1_normed_ortho
poly_path = np.concatenate([poly_path_1, poly_path_2[::-1, :]])
assert shapely.geometry.LineString(poly_path).is_simple, \
'Outer lines of parameterized wg intersect. Try using lower bend radii or smaller a smaller wg'
# Now add the shapely objects and do book keeping
polygon = shapely.geometry.Polygon(poly_path)
assert polygon.is_valid, 'Generated polygon path is not valid: %s' % \
shapely.validation.explain_validity(polygon)
polygons.append(polygon)
polygon = shapely.geometry.MultiPolygon(polygons)
outline_poly_path_1 = sample_coordinates - np.sum(
sample_width,
axis=-1)[..., None] / 2 * sample_coordinates_d1_normed_ortho
outline_poly_path_2 = sample_coordinates + np.sum(
sample_width,
axis=-1)[..., None] / 2 * sample_coordinates_d1_normed_ortho
outline = shapely.geometry.Polygon(
np.concatenate([outline_poly_path_1,
outline_poly_path_2[::-1, :]]))
length = np.sum(
np.linalg.norm(np.diff(sample_coordinates, axis=0), axis=1))
self._segments.append((self._current_port.copy(), polygon, outline,
length, sample_coordinates))
self._current_port.origin = sample_coordinates[-1]
# If the width does not need to be a list, convert it back to a scalar
self._current_port.width = sample_width[-1]
self._current_port.angle = np.arctan2(sample_coordinates_d1[-1][1],
sample_coordinates_d1[-1][0])
return self
def add_cubic_bezier_path(self, p0, p1, p2, p3, width=None, **kwargs):
"""
Add a cubic bezier path to the waveguide.
Coordinates are in the "waveguide tip coordinate system", so the first point will probably be p0 == (0, 0).
Note that your bezier curve undergoes the same restrictions as a parameterized path. Don't self-intersect it and
don't use small bend radii.
:param p0: 2 element tuple like coordinates
:param p1: 2 element tuple like coordinates
:param p2: 2 element tuple like coordinates
:param p3: 2 element tuple like coordinates
:param width: Width of the waveguide, as passed to :func:add_parameterized_path
:param kwargs: Optional keyword arguments, passed to :func:add_parameterized_path
:return: Changed waveguide
:rtype: Waveguide
"""
bezier_curve = CubicBezierCurve(p0, p1, p2, p3)
self.add_parameterized_path(path=bezier_curve.evaluate,
path_derivative=bezier_curve.evaluate_d1,
width=width,
path_function_supports_numpy=True,
**kwargs)
return self
def add_bezier_to(self,
final_coordinates,
final_angle,
bend_strength,
width=None,
**kwargs):
try:
bs1, bs2 = float(bend_strength[0]), float(bend_strength[1])
except (KeyError, TypeError):
bs1 = bs2 = float(bend_strength)
final_port = Port(final_coordinates, final_angle, self.width)
p0 = (0, 0)
p1 = self._current_port.longitudinal_offset(
bs1).origin - self._current_port.origin
p2 = final_port.longitudinal_offset(
-bs2).origin - self._current_port.origin
p3 = final_coordinates - self._current_port.origin
tmp_wg = Waveguide.make_at_port(
self._current_port.copy().set_port_properties(angle=0))
tmp_wg.add_cubic_bezier_path(p0, p1, p2, p3, width=width, **kwargs)
self._segments.append(
(self._current_port.copy(), tmp_wg.get_shapely_object(),
tmp_wg.get_shapely_outline(), tmp_wg.length,
tmp_wg.center_coordinates))
self._current_port = tmp_wg.current_port
return self
def add_bezier_to_port(self, port, bend_strength, width=None, **kwargs):
if not width and not np.isclose(np.array(self.width),
np.array(port.width)):
def width(t):
return t * (port.width - self.width) + self.width
supports_numpy = True
else:
supports_numpy = False
kwargs['width_function_supports_numpy'] = kwargs.get(
'width_function_supports_numpy', supports_numpy)
self.add_bezier_to(port.origin, port.inverted_direction.angle,
bend_strength, width, **kwargs)
return self
def add_route_single_circle_to(self,
final_coordinates,
final_angle,
final_width=None,
max_bend_strength=None,
on_line_only=False):
"""
Connect two points by straight lines and one circle.
Works for geometries like round edges and others. The final straight line can also be omitted so that
the waveguide only end on the line described by the support vector and angle.
By default, this method tries to route to the target with the greatest possible circle. But the valid
bending range may be limited via the `max_bend_strength` parameter.
This method does not work for geometries which cannot be connected only by straight lines and one
circle, such as parallel lines etc.
Still, this method can prove extremely useful for routing to i.e. grating couplers etc.
:param final_coordinates: Final destination point.
:param final_angle: Final angle of the waveguide.
:param final_width: Final width of the waveguide.
:param max_bend_strength: The maximum allowed bending radius.
:param on_line_only: Omit the last straight line and only route to described line.
"""
# We are given an out angle, but the internal math is for inward pointing lines
final_angle = normalize_phase(final_angle) + np.pi
final_width = final_width if final_width is not None else self.width
# We need to to some linear algebra. We first find the intersection of the two waveguides
r1 = self._current_port.origin
r2 = np.array(final_coordinates)
intersection_point, distance = find_line_intersection(
r1, self.angle, r2, final_angle)
assert distance[
0] >= 0, 'Origin waveguide is too close to target. No curve possible'
assert on_line_only or distance[
1] >= 0, 'Target position is too close to target. No curve possible'
# Calculate the angle bisector
u1 = np.array([np.cos(self.angle), np.sin(self.angle)])
u2 = np.array([np.cos(final_angle), np.sin(final_angle)])
u_half = u1 + u2
half_angle = np.arctan2(u_half[1], u_half[0])
diff_angle = normalize_phase(self.angle - final_angle - np.pi)
_, r1 = find_line_intersection(r1, self.angle + np.pi / 2,
intersection_point, half_angle)
if not on_line_only:
max_poss_radius = min(
np.abs([
r1[0], distance[0] / np.tan(diff_angle / 2),
distance[1] / np.tan(diff_angle / 2)
]))
else:
max_poss_radius = min(
np.abs([r1[0], distance[0] / np.tan(diff_angle / 2)]))
radius = min([max_bend_strength, max_poss_radius
]) if max_bend_strength is not None else max_poss_radius
d = abs(radius * np.tan(diff_angle / 2))
if on_line_only:
segments = [distance[0] - d, radius * diff_angle]
else:
segments = [distance[0] - d, radius * diff_angle, distance[1] - d]
segment_ratio = np.cumsum(segments / sum(segments))
segment_widths = [(final_width - self.current_port.width) * ratio +
self.current_port.width for ratio in segment_ratio]
tmp_wg = Waveguide.make_at_port(self._current_port)
tmp_wg.add_straight_segment(length=distance[0] - d,
final_width=segment_widths[0])
tmp_wg.add_bend(-diff_angle, radius, final_width=segment_widths[1])
if not on_line_only:
tmp_wg.add_straight_segment(distance[1] - d,
final_width=segment_widths[2])
self._segments.append(
(self._current_port.copy(), tmp_wg.get_shapely_object(),
tmp_wg.get_shapely_outline(), tmp_wg.length,
tmp_wg.center_coordinates))
self._current_port = tmp_wg.current_port
return self
def add_route_single_circle_to_port(self,
port,
max_bend_strength=None,
on_line_only=False):
"""
Connect to port by straight lines and one circle.
Helper function to conveniently call add_route_single_circle_to.
:param port: Target port.
:param max_bend_strength: The maximum allowed bending radius.
:param on_line_only: Omit the last straight line and only route to line described by port.
"""
self.add_route_single_circle_to(port.origin,
port.inverted_direction.angle,
port.width, max_bend_strength,
on_line_only)
return self
def add_route_straight_to_port(self, port):
"""
Add a straight segment to a given port. The added segment will keep
the angle of the current port at the start and use the angle of the
target port at the end. If the ports are laterally shifted, this
will result in a trapezoidal shape.
The width will be linearly tapered to that of the target port.
:param port: Target port.
"""
start_width = np.array(self.current_port.width)
final_width = np.array(port.width)
c, s = np.cos(-self.current_port.angle), np.sin(
-self.current_port.angle)
R = np.array([[c, -s], [s, c]])
end_point = R @ (np.array(port.origin) -
np.array(self.current_port.origin))
angle_diff = port.inverted_direction.angle - self.current_port.angle
start_deriv = np.array([1, 0])
end_deriv = np.array([np.cos(angle_diff), np.sin(angle_diff)])
self.add_parameterized_path(path=lambda t: np.array([0, 0]) *
(1 - t) + end_point * t,
width=lambda t: start_width *
(1 - t) + final_width * t,
path_derivative=lambda t: start_deriv *
(1 - t) + end_deriv * t,
sample_points=2,
sample_distance=0)
return self
def add_straight_segment_to_intersection(self, line_origin, line_angle,
**line_kw):
"""
Add a straight line until it intersects with an other line.
The other line is described by the support vector and the line angle.
:param line_origin: Intersection line support vector.
:param line_angle: Intersection line angle.
:param line_kw: Parameters passed on to add_straight_segment.
:raise ArithmeticError: When there is no intersection due to being parallel or if
the intersection is behind the waveguide.
"""
r1 = self._current_port.origin
r2 = np.array(line_origin)
try:
intersection_point, distance = find_line_intersection(
r1, self.angle, r2, line_angle)
if np.isclose(distance[0], 0):
return self
elif distance[0] < 0:
raise ArithmeticError(
'No forward intersection of waveguide with given line')
self.add_straight_segment(distance[0], **line_kw)
except linalg.LinAlgError:
# We do not find an intersection if lines are parallel
raise ArithmeticError(
'There is no intersection with the given line')
return self
def add_straight_segment_until_x(self, x, **line_kw):
"""
Add straight segment until the given x value is reached.
:param x: value
:param line_kw: Parameters passed on to add_straight_segment.
"""
self.add_straight_segment_to_intersection([x, 0], np.pi / 2, **line_kw)
return self
def add_straight_segment_until_y(self, y, **line_kw):
"""
Add straight segment until the given y value is reached.
:param y: value
:param line_kw: Parameters passed on to add_straight_segment.
"""
self.add_straight_segment_to_intersection([0, y], 0, **line_kw)
return self
def add_straight_segment_until_level_of_port(self, port, **line_kw):
"""
Add a straight line until it is on the same level as the given port. If several ports are given in a list,
the most distant port is chosen.
In this context "on the same level" means the intersection of the waveguide with the line
orthogonal to the given port.
:param port: The port or a list of ports.
:param line_kw:
"""
if isinstance(port, collections.Iterable):
direction = (np.cos(self.angle), np.sin(self.angle))
distances = np.array([np.dot(p.origin, direction) for p in port])
furthest_port_idx = distances.argmax()
port = port[furthest_port_idx]
self.add_straight_segment_to_intersection(port.origin,
port.angle - np.pi / 2,
**line_kw)
return self
def add_left_bend(self, radius, angle=np.pi / 2):
"""
Add a left turn (90° or as defined by angle) with the given bend radius
"""
return self.add_bend(angle, radius)
def add_right_bend(self, radius, angle=np.pi / 2):
"""
Add a right turn (90° or as defined by angle) with the given bend radius
"""
return self.add_bend(-angle, radius)
def port(self):
port = Port(self.origin, self.angle, self.width)
return port.longitudinal_offset(2 * self.splitter_length + 4 * self.bend_radius + self.horizontal_length)
def make_nanowire(self):
# U-shaped nanowire
self.nanowire_port = Port(origin=(0, 0), angle=0, width=self.nw_width)
nw = Waveguide.make_at_port(self.nanowire_port, width=self.nw_width)
tip_radius = 0.5 * self.nw_gap + 0.5 * self.nw_width
nw.add_bend(0.5 * np.pi, tip_radius)
nw.add_straight_segment(self.nw_length - tip_radius)
# Wing Square Pads which will overlap with the contact pads
wing_tapering_origin = np.array(nw.current_port.origin)
self.wing_pad_bottom_left = wing_tapering_origin + (
(0.5 * self.wing_span - (self.nw_width + 0.5 * self.nw_gap)),
0.5 * self._origin_port.width)
self.wing_pad_bottom_right = self.wing_pad_bottom_left + (
0.5 * self.wing_span, 0)
self.wing_pad_top_right = self.wing_pad_bottom_right + (
0, self.wing_height)
self.wing_pad_top_left = self.wing_pad_bottom_left + (0,
self.wing_height)
wing_pad = Polygon([
self.wing_pad_bottom_left, self.wing_pad_bottom_right,
self.wing_pad_top_right, self.wing_pad_top_left
])
# Bezier tapering from nanowire to wing pads
nw_left_side_coord = wing_tapering_origin - (0.5 * self.nw_width, 0)
nw_right_side_coord = wing_tapering_origin + (0.5 * self.nw_width, 0)
self.aux_origin_top_line = nw_left_side_coord + np.array(
[0, 0.2 * (self.wing_pad_top_left[1] - nw_left_side_coord[1])])
self.aux_dest_top_line = nw_left_side_coord + np.array([
0.8 * (self.wing_pad_top_left[0] - nw_left_side_coord[0]), 0.4 *
(self.wing_pad_top_left[1] - nw_left_side_coord[1])
])
wing_tapering_top_line = self._cub_bezier(nw_left_side_coord,
self.wing_pad_top_left,
self.aux_origin_top_line,
self.aux_dest_top_line)
self.aux_origin_bottom_line = nw_right_side_coord + np.array([
0.1 * (self.wing_pad_bottom_left[0] - nw_right_side_coord[0]),
self.wing_pad_bottom_left[1] - nw_right_side_coord[1]
])
self.aux_dest_bottom_line = nw_right_side_coord + np.array(
[0, 0.5 * (self.wing_pad_bottom_left[1] - nw_right_side_coord[1])])
wing_tapering_bottom_line = self._cub_bezier(
self.wing_pad_bottom_left, nw_right_side_coord,
self.aux_origin_bottom_line, self.aux_dest_bottom_line)
wing_tapering = Polygon(wing_tapering_top_line +
wing_tapering_bottom_line)
wing = geometric_union([wing_pad, wing_tapering])
nw = geometric_union([nw, wing])
nw_l = shapely.affinity.scale(nw,
xfact=-1.0,
yfact=1.0,
zfact=1.0,
origin=[
self.nanowire_port.origin[0],
self.nanowire_port.origin[1], 0
])
nw = geometric_union([nw, nw_l])
nw = shapely.affinity.translate(nw, yoff=0.5 * self.nw_width)
nw = shapely.affinity.rotate(nw,
self._origin_port.angle - 0.5 * np.pi,
origin=[0, 0],
use_radians=True)
self.nw = shapely.affinity.translate(nw,
xoff=self._origin_port.origin[0],
yoff=self._origin_port.origin[1])
re_origin = self._origin_port.origin
re_angle = self._origin_port.angle - 0.5 * np.pi
rep = Port(origin=re_origin, angle=re_angle, width=self.wing_height)
self.rep = rep.longitudinal_offset(
self.wing_pad_bottom_left[0] + 0.25 *
self.wing_span).parallel_offset(self.wing_pad_bottom_left[1] +
0.5 * self.wing_height)
self.lep = self.rep.longitudinal_offset(-1.5 * self.wing_span).rotated(
np.pi)
class StripToSlotModeConverter:
"""
Generates a strip to slot mode converter as presented by Palmer et. al https://doi.org/10.1109/JPHOT.2013.2239283.
If the input port width is a scalar und the final width is an array, a strip to slot mode converter is generated.
On the other hand, if the input port width is an array and the final width is a scaler, a slot to strip mode
converter is generated.
"""
def __init__(self, origin, angle, width, taper_length, final_width,
pre_taper_length, pre_taper_width):
"""
:param origin: origin of the mode converter
:param angle: angle of the mode converter
:param width: width of the mdoe converter. Scalar if strip to slot, array if slot to strip
:param taper_length: length of the taper
:param final_width: final width of the mode converter. Array if strip to slot, scalar if slot to strip
:param pre_taper_length: length of the pre taper
:param pre_taper_width: width of the pre taper
"""
self._taper_length = taper_length
self._in_port = Port(origin, angle, width)
self._final_width = final_width
self._pre_taper_length = pre_taper_length
self._pre_taper_width = pre_taper_width
self._waveguide = None
@classmethod
def make_at_port(cls, port, taper_length, final_width, pre_taper_length,
pre_taper_width):
"""
:param port: port of the taper (origin, angle, width)
:param taper_length: length of the taper
:param final_width: final width of the mode converter. Array if strip to slot, scalar if slot to strip
:param pre_taper_length: length of the pre taper
:param pre_taper_width: width of the pre taper
:return:
"""
return cls(port.origin, port.angle, port.width, taper_length,
final_width, pre_taper_length, pre_taper_width)
@property
def in_port(self):
"""
Returns the input port of the mode converter
:return: port
"""
return self._in_port.copy()
@property
def out_port(self):
"""
Returns the output port of the mode converter
:return: port
"""
port = self._in_port.longitudinal_offset(self._taper_length +
self._pre_taper_length)
port.width = self._final_width
return port
def get_shapely_object(self):
"""
Generates the mode converter. If the input port width is a scalar und the final width is an array, a strip to
slot mode converter is generated. On the other hand, if the input port width is an array and the final width is
a scaler, a slot to strip mode converter is generated.
:return: shapely object
"""
if self._waveguide:
return self._waveguide.get_shapely_object()
if np.array(self._in_port.width).size == 1:
# strip to slot mode converter
strip_width = self.in_port.width
slot_width = self._final_width
else:
# slot to strip mode converter
slot_width = self.in_port.width
strip_width = self._final_width
def pre_taper_width(t):
return [
slot_width[0] * t + self._pre_taper_width * (1 - t),
slot_width[1] + (slot_width[0] - self._pre_taper_width) *
(1 - t), strip_width, slot_width[0] + slot_width[1]
]
def taper_width(t):
return [
slot_width[0], slot_width[1],
slot_width[2] * t + strip_width * (1 - t),
(slot_width[0] + slot_width[1]) * (1 - t)
]
self._waveguide = Waveguide.make_at_port(self._in_port)
if np.array(self._in_port.width).size == 1:
# strip to slot mode converter
self._waveguide.add_parameterized_path(
lambda t: [t * self._pre_taper_length, 0],
width=pre_taper_width)
self._waveguide.add_parameterized_path(
lambda t: [t * self._taper_length, 0], width=taper_width)
else:
# slot to strip mode converter
self._waveguide.add_parameterized_path(
lambda t: [t * self._taper_length, 0],
width=lambda t: taper_width(1 - t))
self._waveguide.add_parameterized_path(
lambda t: [t * self._pre_taper_length, 0],
width=lambda t: pre_taper_width(1 - t))
return self._waveguide.get_shapely_object()