Examples

Tutorial

The following code is a sample to quickly demonstrate some features of gdspy.

Download sample file

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######################################################################
#                                                                    #
#  Copyright 2009-2017 Lucas Heitzmann Gabrielli.                    #
#  This file is part of gdspy, distributed under the terms of the    #
#  Boost Software License - Version 1.0.  See the accompanying       #
#  LICENSE file or <http://www.boost.org/LICENSE_1_0.txt>            #
#                                                                    #
######################################################################

import numpy
import gdspy

print('Using gdspy module version ' + gdspy.__version__)

# ------------------------------------------------------------------ #
#      POLYGONS
# ------------------------------------------------------------------ #

# First we need a cell to add the polygons to.
poly_cell = gdspy.Cell('POLYGONS')

# We define the polygon through its vertices.
points = [(0, 0), (2, 2), (2, 6), (-6, 6), (-6, -6), (-4, -4), (-4, 4), (0, 4)]

# Create the polygon on layer 1.
poly1 = gdspy.Polygon(points, 1)

# Add the new polygon to the cell.
poly_cell.add(poly1)

# Create another polygon from the same set of points, but rotate it
# 180 degrees and add it to the cell.
poly2 = gdspy.Polygon(points, 1).rotate(numpy.pi)
poly_cell.add(poly2)

# To create rectangles we don't need to give the 4 corners, only 2.
# Note that we don't need to create a variable if we are not going to
# use it, just add the rectangle directly to the cell.  Create a
# rectangle in layer 2.
poly_cell.add(gdspy.Rectangle((18, 1), (22, 2), 2))

# There are no circles in the GDSII specification, so rounded shapes
# are actually many-sided polygons.  Create a circle in layer 2,
# centered at (27, 2), and with radius 2.
poly_cell.add(gdspy.Round((27, 2), 2, layer=2))

# The Round class is quite versatile: it provides circles, pie slices,
# rings and ring sections, like this one in layer 2.
poly_cell.add(
    gdspy.Round(
        (23.5, 7),
        15,
        inner_radius=14,
        initial_angle=-2.0 * numpy.pi / 3.0,
        final_angle=-numpy.pi / 3.0,
        layer=2))

# ------------------------------------------------------------------ #
#      PATHS
# ------------------------------------------------------------------ #

path_cell = gdspy.Cell('PATHS')

# Start a path from the origin with width 1.
path1 = gdspy.Path(1, (0, 0))

# Add a straight segment to the path in layer 1, datatype 1, with length
# 3, going in the '+x' direction. Since we'll use this layer/datatype
# configuration again, we can setup a dict containing this info.
spec = {'layer': 1, 'datatype': 1}
path1.segment(3, '+x', **spec)

# Add a curve to the path by specifying its radius as 2 and its initial
# and final angles.
path1.arc(2, -numpy.pi / 2.0, numpy.pi / 6.0, **spec)

# Add another segment to the path in layer 1, with length 4 and
# pointing in the direction defined by the last piece we added above.
path1.segment(4, **spec)

# Add a curve using the turn command.  We specify the radius 2 and
# turning angle. The agnle can also be specified with 'l' and 'r' for
# left and right turns of 90 degrees, or 'll' and 'rr' for 180 degrees.
path1.turn(2, -2.0 * numpy.pi / 3.0, **spec)

# Final piece of the path.  Add a straight segment and tapper the path
# width from the original 1 to 0.5.
path1.segment(3, final_width=0.5, **spec)
path_cell.add(path1)

# We can also create parallel paths simultaneously.  Start 2 paths with
# width 0.5 each,nd pitch 1, originating where our last path ended.
path2 = gdspy.Path(0.5, (path1.x, path1.y), number_of_paths=2, distance=1)

# Add a straight segment to the paths gradually increasing their
# distance to 1.5, in the direction in which the last path ended.
spec['layer'] = 2
path2.segment(3, path1.direction, final_distance=1.5, **spec)

# Path commands can be concatenated.  Add a turn and a tapper segment
# in one expression, followed by a final turn.
path2.turn(2, -2.0 * numpy.pi / 3.0, **spec).segment(
    4, final_distance=1, **spec)
path2.turn(4, numpy.pi / 6.0, **spec)
path_cell.add(path2)

# Create another single path 0.5 wide, starting where the path above
# ended, and add to it a line segment in the 3rd layer in the '-y'
# direction.
path3 = gdspy.Path(0.5, (path2.x, path2.y))
path3.segment(1, '-y', layer=3)


# We can create paths based on parametric curves. First we need to
# define the curve function, with 1 argument.  This argument will vary
# from 0 to 1 and the return value should be the (x, y) coordinates of
# the path.  This could be a lambda-expression if the function is
# simple enough.  We will create a spiral path.  Note that the function
# returns (0, 0) when t=0, so that our path is connected.
def spiral(t):
    r = 4 - 3 * t
    theta = 5 * t * numpy.pi
    x = 4 - r * numpy.cos(theta)
    y = -r * numpy.sin(theta)
    return (x, y)


# We can also create the derivative of the curve to pass to out path
# path member, otherwise it will be numerically calculated.  In the
# spiral case we don't want the exact derivative, but the derivative of
# the spiral as if its radius was constant.  This will ensure that our
# path is connected at the start (geometric problem of this kind of
# spiral).
def dspiral_dt(t):
    theta = 5 * t * numpy.pi
    dx_dt = numpy.sin(theta)
    dy_dt = -numpy.cos(theta)
    return (dx_dt, dy_dt)


# Add the parametric spiral to the path in layer 3.  Note that we can
# still tapper the width (linearly or with a taper function).  To make
# the curve smoother, we increase the number of evaluations of the
# function (fracture will be performed automatically to ensure polygons
# with less than 200 points).
path3.parametric(
    spiral,
    dspiral_dt,
    final_width=lambda t: 0.1 + abs(0.4 * (1 - 2 * t)**3),
    number_of_evaluations=600,
    layer=3)
path_cell.add(path3)

# Polygonal paths are defined by the points they pass through.  The
# width of the path can be given as a number, representing the path
# width along is whole extension, or as a list, where each element is
# the width of the path at one point.  Our path will have width 0.5 in
# all points, except the last, where it will tapper up to 1.5.  More
# than 1 path can be defined in parallel as well (useful for buses).
# The distance between the paths work the same way as the width: it's
# either a constant number, or a list.  We create 5 parallel paths that
# are larger and further apart on the last point. The paths are put in
# layers 4 and 5. Since we have 5 paths, the list of layers will be
# run more than once, so the 5 paths will actually be in layers 4, 5, 4,
# 5, and 4.
points = [(20, 12), (24, 8), (24, 4), (24, -2)]
widths = [0.5] * (len(points) - 1) + [1.5]
distances = [0.8] * (len(points) - 1) + [2.4]
polypath = gdspy.PolyPath(
    points, widths, number_of_paths=5, distance=distances, layer=[4, 5])

# We can round the corners of any Polygon or PolygonSet with the fillet
# method. Here we use a radius of 0.2.
# polypath.fillet(0.2)
path_cell.add(polypath)

# L1Paths use only segments in 'x' and 'y' directions, useful for some
# lithography mask writers.  We specify a path composed of 16 segments
# of length 4.  The turns after each segment can be either 90 degrees
# CCW (positive) or CW (negative).  The absolute value of the turns
# produces a scaling of the path width and distance between paths in
# segments immediately after the turn.
lengths = [4] * 8
turns = [-1, -1, 1, 1, -1, -2, 1, 0.5]
l1path = gdspy.L1Path(
    (-1, -11),
    '+y',
    0.5,
    lengths,
    turns,
    number_of_paths=3,
    distance=0.7,
    layer=6)
path_cell.add(l1path)

# ------------------------------------------------------------------ #
#      POLYGON OPERATIONS
# ------------------------------------------------------------------ #

# Boolean operations can be executed with either gdspy polygons or
# point lists).  The operations are union, intersection, subtraction,
# symmetric subtracion (respectively 'or', 'and', 'not', 'xor').
oper_cell = gdspy.Cell('OPERATIONS')

# Here we subtract the previously created spiral from a rectangle with
# the 'not' operation.
oper_cell.add(
    gdspy.fast_boolean(
        gdspy.Rectangle((10, -4), (17, 4)), path3, 'not', layer=1))

# Polygon offset (inset and outset) can be used, for instance, to
# define safety margins around shapes.

spec = {'layer': 7}
path4 = gdspy.Path(0.5, (21, -5)).segment(3, '+x', **spec)\
        .turn(4, 'r', **spec).turn(4, 'rr', **spec)\
        .segment(3, **spec)
oper_cell.add(path4)

# Merge all parts into a single polygon.
merged = gdspy.fast_boolean(path4, None, 'or', max_points=0)

# Offset the path shape by 0.5 and add it to the cell.
oper_cell.add(gdspy.offset(merged, 1, layer=8))

# ------------------------------------------------------------------ #
#      SLICING POLYGONS
# ------------------------------------------------------------------ #

# If there is the need to cut a polygon or set of polygons, it's better
# to use the slice function than set up a boolean operation, since it
# runs much faster.  Slices are multiple cuts perpendicular to an axis.
slice_cell = gdspy.Cell('SLICE')
original = gdspy.Round((0, 0), 10, inner_radius=5)

# Slice the original ring along x = -7 and x = 7.
result = gdspy.slice(original, [-7, 7], 0, layer=1)

# The result is a tuple of polygon sets, one for each slice.  To keep
# add the region betwen our 2 cuts, we chose result[1].
slice_cell.add(result[1])

# If the cut needs to be at an angle we can rotate the geometry, slice
# it, and rotate back.
original = gdspy.PolyPath([(12, 0), (12, 8), (28, 8), (28, -8), (12, -8),
                           (12, 0)], 1, 3, 2)
original.rotate(numpy.pi / 3, center=(20, 0))
result = gdspy.slice(original, 7, 1, layer=2)
result[0].rotate(-numpy.pi / 3, center=(20, 0))
slice_cell.add(result[0])

# ------------------------------------------------------------------ #
#      REFERENCES AND TEXT
# ------------------------------------------------------------------ #

# Cells can contain references to other cells.
ref_cell = gdspy.Cell('REFS')
ref_cell.add(gdspy.CellReference(poly_cell, (0, 30), x_reflection=True))
ref_cell.add(gdspy.CellReference(poly_cell, (25, 0), rotation=180))

# References can be whole arrays. Add an array of the operations cell
# with 2 lines and 3 columns and 1st element at (25, 10).
ref_cell.add(
    gdspy.CellArray('OPERATIONS', 3, 2, (35, 30), (25, 10), magnification=1.5))

# Text are also sets of polygons. They have edges parallel to 'x' and
# 'y' only.
ref_cell.add(
    gdspy.Text(
        'Created with gsdpy ' + gdspy.__version__, 7, (-7, -35), layer=6))

# Labels are special text objects which don't define any actual
# geometry, but can be used to annotate the drawing.  Rotation,
# magnification and reflection of the text are not supported by the
# included GUI, but they are included in the resulting GDSII file.
ref_cell.add(
    gdspy.Label(
        'Created with gdspy ' + gdspy.__version__, (-7, -36), 'nw', layer=6))

# ------------------------------------------------------------------ #
#      Translation
# ------------------------------------------------------------------ #

trans_cell = gdspy.Cell('TRANS')

# Any geometric object can be translated by providing the distance to
# translate in the x-direction and y-direction:  translate(dx, dy)
rect1 = gdspy.Rectangle((80, 0), (81, 1), 1)
rect1.translate(2, 0)
trans_cell.add(rect1)

# Translatable objects can also be copied & translated in the same way.
rect2 = gdspy.Rectangle((80, 0), (81, 1), 2)
rect3 = gdspy.copy(rect2, 0, 3)
trans_cell.add(rect2)
trans_cell.add(rect3)

# Reference Cells are also translatable, and thus copyable.
ref1 = gdspy.CellReference(poly_cell, (25, 0), rotation=180)
ref2 = gdspy.copy(ref1, 30, 30)
trans_cell.add(ref1)
trans_cell.add(ref2)

# Same goes for Labels & Text
text1 = gdspy.Text(
    'Created with gsdpy ' + gdspy.__version__, 7, (-7, -35), layer=6)
text2 = gdspy.copy(text1, 0, -20)
label1 = gdspy.Label(
    'Created with gdspy ' + gdspy.__version__, (-7, -36), 'nw', layer=6)
label2 = gdspy.copy(label1, 0, -20)
trans_cell.add(text1)
trans_cell.add(text2)
trans_cell.add(label1)
trans_cell.add(label2)

# ------------------------------------------------------------------ #
#      OUTPUT
# ------------------------------------------------------------------ #

# Output the layout to a GDSII file (default to all created cells).
# Set the units we used to micrometers and the precision to nanometers.
gdspy.write_gds('tutorial.gds', unit=1.0e-6, precision=1.0e-9)

# ------------------------------------------------------------------ #
#      IMPORT
# ------------------------------------------------------------------ #

# Import the file we just created, and extract the cell 'POLYGONS'. To
# avoid naming conflict, we will rename all cells.
gdsii = gdspy.GdsLibrary()
gdsii.read_gds(
    'tutorial.gds',
    rename={
        'POLYGONS': 'IMPORT_POLY',
        'PATHS': 'IMPORT_PATHS',
        'OPERATIONS': 'IMPORT_OPER',
        'SLICE': 'IMPORT_SLICE',
        'REFS': 'IMPORT_REFS',
        'TRANS': 'IMPORT_TRANS'
    },
    layers={1: 7,
            2: 8,
            3: 9})

# Now we extract the cells we want to actually include in our current
# structure. Note that the referenced cells will be automatically
# extracted as well.
gdsii.extract('IMPORT_REFS')

# ------------------------------------------------------------------ #
#      VIEWER
# ------------------------------------------------------------------ #

# View the layout using a GUI.  Full description of the controls can
# be found in the online help at http://gdspy.sourceforge.net/
gdspy.LayoutViewer()

Integrated Photonics

This example demonstrates the use of gdspy primitives to create more complex structures.

These structures are commonly used in the field of integrated photonics.

Download sample file

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######################################################################
#                                                                    #
#  Copyright 2009-2017 Lucas Heitzmann Gabrielli.                    #
#  This file is part of gdspy, distributed under the terms of the    #
#  Boost Software License - Version 1.0.  See the accompanying       #
#  LICENSE file or <http://www.boost.org/LICENSE_1_0.txt>            #
#                                                                    #
######################################################################

import numpy
import gdspy


def waveguide(path,
              points,
              finish,
              bend_radius,
              number_of_points=0.01,
              direction=None,
              layer=0,
              datatype=0):
    '''
    Easy waveguide creation tool with absolute positioning.

    path             : `gdspy.Path` which servers as base for the waveguide
    points           : coordinates along which the waveguide will travel
    finish           : end point of the waveguide
    bend_radius      : radius of the turns in the waveguide
    number_of_points : same as in `path.turn`
    direction        : starting direction
    layer            : GDSII layer number
    datatype         : GDSII datatype number

    Return `path`.
    '''
    if direction is not None:
        path.direction = direction
    axis = 0 if path.direction[1] == 'x' else 1
    points.append(finish[(axis + len(points)) % 2])
    n = len(points)
    if points[0] > (path.x, path.y)[axis]:
        path.direction = ['+x', '+y'][axis]
    else:
        path.direction = ['-x', '-y'][axis]
    for i in range(n):
        path.segment(
            abs(points[i] - (path.x, path.y)[axis]) - bend_radius,
            layer=layer,
            datatype=datatype)
        axis = 1 - axis
        if i < n - 1:
            goto = points[i + 1]
        else:
            goto = finish[axis]
        if (goto > (path.x, path.y)[axis]) ^ ((path.direction[0] == '+') ^
                                              (path.direction[1] == 'x')):
            bend = 'l'
        else:
            bend = 'r'
        path.turn(
            bend_radius,
            bend,
            number_of_points=number_of_points,
            layer=layer,
            datatype=datatype)
    return path.segment(
        abs(finish[axis] - (path.x, path.y)[axis]),
        layer=layer,
        datatype=datatype)


def taper(path,
          length,
          final_width,
          final_distance,
          direction=None,
          layer=0,
          datatype=0):
    '''
    Linear tapers for the lazy.

    path        : `gdspy.Path` to append the taper
    length      : total length
    final_width : final width of th taper
    direction   : taper direction
    layer       : GDSII layer number (int or list)
    datatype    : GDSII datatype number (int or list)

    Parameters `layer` and `datatype` must be of the same type. If they are
    lists, they must have the same length. Their length indicate the number of
    pieces that compose the taper.

    Return `path`.
    '''
    if layer.__class__ == datatype.__class__ == [].__class__:
        assert len(layer) == len(datatype)
    elif isinstance(layer, int) and isinstance(datatype, int):
        layer = [layer]
        datatype = [datatype]
    else:
        raise ValueError('Parameters layer and datatype must have the same '
                         'type (either int or list) and length.')
    n = len(layer)
    w = numpy.linspace(2 * path.w, final_width, n + 1)[1:]
    d = numpy.linspace(path.distance, final_distance, n + 1)[1:]
    l = float(length) / n
    for i in range(n):
        path.segment(
            l, direction, w[i], d[i], layer=layer[i], datatype=datatype[i])
    return path


def grating(period,
            number_of_teeth,
            fill_frac,
            width,
            position,
            direction,
            lda=1,
            sin_theta=0,
            focus_distance=-1,
            focus_width=-1,
            evaluations=99,
            layer=0,
            datatype=0):
    '''
    Straight or focusing grating.

    period          : grating period
    number_of_teeth : number of teeth in the grating
    fill_frac       : filling fraction of the teeth with respect to the period
    width           : width of the grating
    position        : grating position (feed point)
    direction       : one of {'+x', '-x', '+y', '-y'}
    lda             : free-space wavelength
    sin_theta       : sine of incidence angle
    focus_distance  : focus distance (negative for straight grating)
    focus_width     : if non-negative, the focusing area is included in the
                      result (usually for negative resists) and this is the
                      width of the waveguide connecting to the grating
    evaluations     : number of parametric evaluations of `path.parametric`
    layer           : GDSII layer number
    datatype        : GDSII datatype number

    Return `PolygonSet`
    '''
    if focus_distance < 0:
        path = gdspy.L1Path(
            (position[0] - 0.5 * width,
             position[1] + 0.5 * (number_of_teeth - 1 + fill_frac) * period),
            '+x',
            period * fill_frac, [width], [],
            number_of_teeth,
            period,
            layer=layer,
            datatype=datatype)
    else:
        neff = lda / float(period) + sin_theta
        qmin = int(focus_distance / float(period) + 0.5)
        path = gdspy.Path(period * fill_frac, position)
        max_points = 199 if focus_width < 0 else 2 * evaluations
        c3 = neff**2 - sin_theta**2
        w = 0.5 * width
        for q in range(qmin, qmin + number_of_teeth):
            c1 = q * lda * sin_theta
            c2 = (q * lda)**2
            path.parametric(
                lambda t: (width * t - w, (c1 + neff * numpy.sqrt(c2 - c3 * (
                    width * t - w)**2)) / c3),
                number_of_evaluations=evaluations,
                max_points=max_points,
                layer=layer,
                datatype=datatype)
            path.x = position[0]
            path.y = position[1]
        if focus_width >= 0:
            path.polygons[0] = numpy.vstack(
                (path.polygons[0][:evaluations, :],
                 ([position] if focus_width == 0 else
                  [(position[0] + 0.5 * focus_width, position[1]),
                   (position[0] - 0.5 * focus_width, position[1])])))
            path.fracture()
    if direction == '-x':
        return path.rotate(0.5 * numpy.pi, position)
    elif direction == '+x':
        return path.rotate(-0.5 * numpy.pi, position)
    elif direction == '-y':
        return path.rotate(numpy.pi, position)
    else:
        return path


if __name__ == '__main__':
    # Examples

    c1 = gdspy.Cell('Example1')
    # Waveguide starts at (0, 0)...
    path = gdspy.Path(0.450, (0, 0))
    # ... then starts in the +y direction up to y=200, then through x=500,
    # and stops at (800, 400). All bends have radius 50.
    waveguide(path, [200, 500], (800, 400), 50, direction='+y')
    c1.add(path)

    # More useful example including a taper and a grating:
    c2 = gdspy.Cell('Example2')
    for i in range(3):
        path = gdspy.Path(0.120, (50 * i, 0))
        taper(
            path,
            75,
            0.450,
            0,
            '+y',
            layer=list(range(5, 1, -1)),
            datatype=list(range(1, 5)))
        waveguide(
            path, [300 - 20 * i], (500 + 50 * i, 425), 50, layer=1, datatype=1)
        c2.add(path)
        c2.add(
            grating(
                0.626,
                28,
                0.5,
                19, (path.x, path.y),
                path.direction,
                1.55,
                numpy.sin(numpy.pi * 8 / 180),
                21.5,
                2 * path.w,
                layer=1,
                datatype=1))

    # Straight grating and positive resist example
    c3 = gdspy.Cell('Example3')
    spec = {'layer': 4, 'datatype': 3}
    lda = 1.55
    gr_width = 10
    gr_per = 0.626
    gr_teeth = 20
    wg_clad = 4
    wg_width = 0.45
    tp_len = 700
    c3.add(
        grating(gr_per, gr_teeth, 0.5, gr_width, (gr_per * gr_teeth, 0), '-x',
                lda, numpy.sin(numpy.pi * 8 / 180), **spec))
    path = gdspy.Path(
        wg_clad, (0, 0), number_of_paths=2, distance=gr_width + wg_clad)
    path.segment(gr_per * gr_teeth, '+x', **spec)
    taper(path, tp_len, wg_clad, wg_width + wg_clad, **spec)
    waveguide(path, [800], (tp_len + gr_per * gr_teeth, 200), 50, 0.1, **spec)
    taper(path, tp_len, wg_clad, gr_width + wg_clad, **spec)
    c3.add(
        grating(gr_per, gr_teeth, 0.5, gr_width, (path.x, path.y),
                path.direction, lda, numpy.sin(numpy.pi * 8 / 180), **spec))
    path.segment(gr_per * gr_teeth, **spec)
    c3.add(path)

    gdspy.LayoutViewer()