Optical waveguides and waveguide templates¶
In IPKISS, optical waveguides are based on two concepts: the waveguide template, and the waveguide itself. The waveguide template defines all the aspects of the waveguide that can be extracted from its cross section:
- how the waveguide is drawn along the shape of the waveguide, i.e. the geometrical cross section;
- the simulation model, e.g. the effective index of the waveguide.
The waveguide is then drawn based on the following properties:
- the path of the waveguide (through the
shape
property); - how the bending is performed.
For a detailed guide, please check the waveguide guide. For a tutorial, please check out the waveguide tutorial on Luceda Academy.
Contents
WindowWaveguideTemplate¶
Most waveguides can be built using windows. A window is a cross-section in a gdsii layer. By defining several windows the cross section of the waveguide can be defined.
-
class
ipkiss3.all.
WindowWaveguideTemplate
(*args, **kwargs)¶ Template PCell for an Optical Waveguide Trace based on TraceWindows.
Parameters: name:
The unique name of the pcell
Views
-
Layout
¶ Parameters: cover_layers: List with type restriction, allowed types: <class ‘ipkiss.primitives.layer.Layer’>
layers that can be used to generate additional coverage of the trace (e.g. manhattan corners)
view_name: str and ( Alphanumeric string or Contains _$ )
The name of the view
windows: List with type restriction, allowed types: <class ‘ipkiss3.pcell.trace.window.window._TraceWindow’>
List of Trace Windows that know how to draw themselves relative to the shape of the Trace
core_layer: __Layer__
layer used to define the core of the waveguide
core_width: float and number > 0
width of the waveguide core
pin_shape: Shape
shape to be used for the pins
trace_template_for_ports: _TraceTemplate.Layout
Trace template to be used for the ports. Default = this template
control_shape_layer: __Layer__
layer on which the control shape is drawn
draw_control_shape: ( bool, bool_, bool or int )
draws the control shape on top of the waveguide
width: float and Real, number and number >= 0
Examples
from technologies import silicon_photonics from ipkiss3.pcell.photonics.waveguide import WindowWaveguideTemplate from ipkiss3.pcell.trace.window.window import PathTraceWindow import ipkiss3.all as i3 class MyWgTemplate(WindowWaveguideTemplate): class Layout(WindowWaveguideTemplate.Layout): core_width = i3.PositiveNumberProperty(doc="Core width of the waveguide") cladding_width = i3.PositiveNumberProperty(doc="Cladding width of the waveguide") def _default_core_width(self): return 0.45 def _default_cladding_width(self): return 4.0 def _default_cover_layers(self): # Layer for Manhattan rectangles (drawn in waveguide bends when the waveguide manhattan parameter = True) return [] def _default_windows(self): return [ PathTraceWindow(layer=i3.TECH.PPLAYER.WG.CORE, start_offset=-0.5 * self.core_width, end_offset=+0.5 * self.core_width), PathTraceWindow(layer=i3.TECH.PPLAYER.WG.CLADDING, start_offset=-0.5 * self.cladding_width, end_offset=+0.5 * self.cladding_width) ] # Instantiate the new waveguide template to use it in our waveguide below wg_tmpl = MyWgTemplate() wg = i3.RoundedWaveguide(trace_template=wg_tmpl) wg_lay = wg.Layout(shape=[(0, 0), (10, 0), (10, 10)]) wg_lay.visualize(annotate=True)
-
Waveguide¶
A Waveguide
is the most basic optical route.
-
class
ipkiss3.all.
Waveguide
(*args, **kwargs)¶ Parameters: trace_template: PCell and _WaveguideTemplate
external_port_names:
Dictionary for remapping of the port names of the contents to the external ports
name:
The unique name of the pcell
Other Parameters: contents: PCell and _Trace, locked
Views
-
Layout
¶ Parameters: control_shape_layer: __Layer__
layer on which the control shape is drawn
cover_layers: List with type restriction, allowed types: <class ‘ipkiss.primitives.layer.Layer’>
layers that can be used to generate additional coverage of the trace (e.g. manhattan corners)
draw_control_shape: ( bool, bool_, bool or int )
draws the control shape on top of the waveguide
flatten_contents: ( bool, bool_, bool or int )
if True, it will insert the contents as elements in the layout, rather than as an Instance
view_name: str and ( Alphanumeric string or Contains _$ )
The name of the view
core_layer: __Layer__
layer used to define the core of the waveguide
input_port: TracePort
output_port: TracePort
trace_template_for_ports: _TraceTemplate.Layout
Trace template to be used for the ports.
shape: Shape
Shape from which the Trace is calculated
contents_transformation: GenericNoDistortTransform
Other Parameters: center_line_shape: locked
Automatically calculated shape of the center line of the trace
-
RoundedWaveguide¶
A RoundedWaveguide
rounds the waveguide according to a preset rounding_algorithm
.
-
class
ipkiss3.all.
RoundedWaveguide
(*args, **kwargs)¶ Parameters: trace_template: PCell and _WaveguideTemplate
external_port_names:
Dictionary for remapping of the port names of the contents to the external ports
name:
The unique name of the pcell
Other Parameters: contents: PCell and _Trace, locked
Views
-
Layout
¶ Parameters: angle_step: float and number > 0
Angle step for rounding.
control_shape_layer: __Layer__
layer on which the control shape is drawn
cover_layers: List with type restriction, allowed types: <class ‘ipkiss.primitives.layer.Layer’>
layers that can be used to generate additional coverage of the trace (e.g. manhattan corners)
draw_control_shape: ( bool, bool_, bool or int )
draws the control shape on top of the waveguide
manhattan: ( bool, bool_, bool or int )
Adds rectangular blocks in the bends to avoid as much as possible non-manhattan angles.
view_name: str and ( Alphanumeric string or Contains _$ )
The name of the view
flatten_contents: ( bool, bool_, bool or int )
if True, it will insert the contents as elements in the layout, rather than as an Instance
core_layer: __Layer__
layer used to define the core of the waveguide
bend_radii: list<number > 0>
Bend radius for every individual bend.
remove_straight_angles: ( bool, bool_, bool or int )
Removes the waypoints with straight angles. Set to False if the algorithm uses waypoint-specific information.
reverse_bends: ( bool, bool_, bool or int )
When set to True, it will generate the bends backwards. This has only effect when the bend algorithm is not symmetric.
reverse_individual_bends: list<( bool, bool_, bool or int )>
When set to True, it will generate the individual bends backwards. This has only effect when the bend algorithm is not symmetric. Should have length equal to the shape for closed shapes, but equal to shape-2 for open shapes.
rounding_algorithms:
Rounding algorithm for every individual bend. Can be circular, spline, … Should have length equal to the shape for closed shapes, but equal to shape-2 for open shapes.
input_port: TracePort
output_port: TracePort
trace_template_for_ports: _TraceTemplate.Layout
Trace template to be used for the ports.
shape: Shape
Shape from which the Trace is calculated
contents_transformation: GenericNoDistortTransform
bend_radius: float and number > 0
Bend radius for the auto-generated bends.
rounding_algorithm:
Rounding algorithm used to generate the bends. Can be circular, spline, ….
Other Parameters: center_line_shape: locked
Automatically calculated shape of the center line of the trace
-
TaperedWaveguide¶
A TaperedWaveguide automatically tapers between two waveguide templates:
one which is defined for the straight sections (straight_trace_template
),
and one which is defined for the start, end and bend sections (trace_template
).
-
class
ipkiss3.all.
TaperedWaveguide
(*args, **kwargs)¶ A Rounded Waveguide that tapers to another template (
straight_trace_template
) in straight sectionsParameters: straight_trace_template: PCell and _TraceTemplate, required
template for the straight sections.
trace_template: PCell and _TraceTemplate
template for the start, end and bend sections.
external_port_names:
Dictionary for remapping of the port names of the contents to the external ports
name:
The unique name of the pcell
Other Parameters: contents: PCell and _Trace, locked
Examples
"""A TaperedWaveguide automatically transitions (=tapers) between different waveguide types. """ from technologies import silicon_photonics import ipkiss3.all as i3 from picazzo3.traces.rib_wg import RibWaveguideTemplate rib_tmpl = RibWaveguideTemplate() rib_tmpl.Layout(core_width=0.6) rib_tmpl_wide = RibWaveguideTemplate() rib_tmpl_wide.Layout(core_width=1.6) twg = i3.TaperedWaveguide(trace_template=rib_tmpl, straight_trace_template=rib_tmpl_wide) lay = twg.Layout(shape=[(0, 0), (30, 0), (30, 60)]) lay.visualize(annotate=True)
"""TaperedWaveguide exposes the same properties as RoundedWaveguide. """ from technologies import silicon_photonics import ipkiss3.all as i3 from picazzo3.traces.rib_wg import RibWaveguideTemplate rib_tmpl = RibWaveguideTemplate() rib_tmpl.Layout(core_width=0.6) rib_tmpl_wide = RibWaveguideTemplate() rib_tmpl_wide.Layout(core_width=1.6) twg = i3.TaperedWaveguide(trace_template=rib_tmpl, straight_trace_template=rib_tmpl_wide) lay = twg.Layout( shape=[(0, 0), (50, 0), (75, 50)], bend_radius=30, # we choose a large angle_step to show how it impacts the discretisation angle_step=20, ) lay.visualize(annotate=True)
Views
-
Layout
¶ Parameters: angle_step: float and number > 0
Angle step for rounding.
control_shape_layer: __Layer__
layer on which the control shape is drawn
core_layer: __Layer__
layer used to define the core of the waveguide
cover_layers: List with type restriction, allowed types: <class ‘ipkiss.primitives.layer.Layer’>
layers that can be used to generate additional coverage of the trace (e.g. manhattan corners)
draw_control_shape: ( bool, bool_, bool or int )
draws the control shape on top of the waveguide
flatten_waveguides: ( bool, bool_, bool or int )
If true, all waveguides will be flattened one level to reduce hierarchy
manhattan: ( bool, bool_, bool or int )
Adds rectangular blocks in the bends to avoid as much as possible non-manhattan angles.
output_port: TracePort
remove_straight_angles: ( ( bool, bool_, bool or int ) ), *None allowed*
Remove waypoints with straight angles. When set to None, it will only remove straight angles when all the expansion parameters are calculated automatically
straight_section_lengths: list<number >= 0>
A list of lengths for the straight_template sections of each path segment.Length of list must be identical to number of segments
straight_section_positions: list<fraction>
A list of relative positions for the straight_template sections of each path segment. Length of list must be identical to number of segments.Each position is a number between 0 (closest to first waypoint) and 1 (closest to last waypoint).0.5 will place the expanded section in the middle of the segment.
taper_lengths: list<number >= 0>
Lengths of the tapers for each section. Length of list must be identical to number of segments.
view_name: str and ( Alphanumeric string or Contains _$ )
The name of the view
min_straight_section_length: float and Real, number and number >= 0
minimum_length of the straight sections.
taper_length: ( float and number > 0 ), *None allowed*
length of the taper between the regular waveguide and the expanded waveguide. Ignored if taper_lengths is set. If
None
, the default taper lengths for each transition are chosen for each transition.flatten_contents: ( bool, bool_, bool or int )
if True, it will insert the contents as elements in the layout, rather than as an Instance
bend_radii: list<number > 0>
Bend radius for every individual bend.
reverse_bends: ( bool, bool_, bool or int )
When set to True, it will generate the bends backwards. This has only effect when the bend algorithm is not symmetric.
reverse_individual_bends: list<( bool, bool_, bool or int )>
When set to True, it will generate the individual bends backwards. This has only effect when the bend algorithm is not symmetric. Should have length equal to the shape for closed shapes, but equal to shape-2 for open shapes.
rounding_algorithms:
Rounding algorithm for every individual bend. Can be circular, spline, … Should have length equal to the shape for closed shapes, but equal to shape-2 for open shapes.
input_port: TracePort
trace_template_for_ports: _TraceTemplate.Layout
Trace template to be used for the ports.
shape: Shape
Shape from which the Trace is calculated
contents_transformation: GenericNoDistortTransform
end_straight: float and Real, number and number >= 0
The length of the straight end section of the route
min_straight: float and Real, number and number >= 0
The minimum length of any straight sections in the route
rounding_algorithm: *None allowed*
rounding algorithm used to generate the bends. Can be circular, spline, …
start_straight: float and Real, number and number >= 0
The length of the straight start section of the route
bend_radius: float and number > 0
Bend radius for the auto-generated bends.
Other Parameters: center_line_shape: locked
Automatically calculated shape of the center line of the trace
min_length_for_taper: float and Real, number and number >= 0, locked
minimum length needed to use tapering
-
Using maximum bend radius¶
It is possible to calculate the maximum bend radius that can be used for each turn in a given shape.
This can then be used with RoundedWaveguide
to obtain a waveguide which uses the maximum possible radius
in each bend.
maximum_bend_radii |
Calculate the maximum bend radius for each turn to be made along a control shape |