Merge pull request #179 from jevillegasd/SBend

Automatic Waveguide SBend

klayout_dot_config/python/SiEPIC/utils/geometry.py

@@ -217,9 +217,12 @@ def _bezier_optimal(angle0, angle3):
     except:
         from SiEPIC.install import install_scipy
         install_scipy()
-
-    from scipy.optimize import minimize
-
+
+    try:
+      from scipy.optimize import minimize
+    except:
+      opt =   scipy.optimize()
+      minimize = opt.minimize()
 
 
     angle0 = fix_angle(angle0)

klayout_dot_config/python/SiEPIC/utils/layout.py

@@ -17,11 +17,12 @@
 TODO: enhance documentation
 TODO: make some of the functions in util use these.
 """
-
 from itertools import repeat
 import pya
 import numpy as np
 from numpy import cos, sin, pi, sqrt
+import math as m
+
 from functools import reduce
 from .sampling import sample_function
 from .geometry import rotate90, rotate, bezier_optimal, curve_length
@@ -243,8 +244,10 @@ def layout_waveguide3(cell, pts, params, debug=True):
             'error: this function cannot handle compound waveguides (%s)' % waveguide_type)
 
     # draw the waveguide
+    sbends = params['sbends'].lower() in ['true', '1', 't', 'y', 'yes'] if 'sbends' in params.keys() else False
     waveguide_length = layout_waveguide2(TECHNOLOGY, layout, cell, [wg['layer'] for wg in params['component']], [
-                                         wg['width'] for wg in params['component']], [wg['offset'] for wg in params['component']], pts, radius, params['adiabatic'], params['bezier'])
+                                         wg['width'] for wg in params['component']], [wg['offset'] for wg in params['component']], 
+                                         pts, radius, params['adiabatic'], params['bezier'], sbends)
 
     # Draw the marking layers
     from SiEPIC.utils import angle_vector
@@ -338,18 +341,20 @@ def layout_waveguide3(cell, pts, params, debug=True):
 - radius: in Microns, e.g., 5
 - adiab: 1 = Bezier curve, 0 = radial bend (arc)
 - bezier: the bezier parameter, between 0 and 0.45 (almost a radial bend)
-
+- sbends (optional): sbends (Boolean)
 Note: bezier parameters need to be simulated and optimized, and will depend on 
     wavelength, polarization, width, etc.  TM and rib waveguides don't benefit from bezier curves
     most useful for TE 
 by Lukas Chrostowski
 '''
 
 
-def layout_waveguide2(TECHNOLOGY, layout, cell, layers, widths, offsets, pts, radius, adiab, bezier):
+def layout_waveguide2(TECHNOLOGY, layout, cell, layers, widths, offsets, pts, radius, adiab, bezier, sbends = True):
     from SiEPIC.utils import arc_xy, arc_bezier, angle_vector, angle_b_vectors, inner_angle_b_vectors, translate_from_normal
     from SiEPIC.extend import to_itype
+    from SiEPIC.utils.geometry import bezier_parallel
     from pya import Path, Polygon, Trans
+
     dbu = layout.dbu
 
     if 'Errors' in TECHNOLOGY:
@@ -365,14 +370,39 @@ def layout_waveguide2(TECHNOLOGY, layout, cell, layers, widths, offsets, pts, ra
         layer = layout.layer(TECHNOLOGY[layers[lr]])
         width = to_itype(widths[lr], dbu)
         offset = to_itype(offsets[lr], dbu)
-        for i in range(1, len(pts)-1):
+
+        it = iter(range(1, len(pts)-1))
+        for i in it:
             turn = ((angle_b_vectors(pts[i]-pts[i-1], pts[i+1]-pts[i])+90) % 360-90)/90
             dis1 = pts[i].distance(pts[i-1])
             dis2 = pts[i].distance(pts[i+1])
             angle = angle_vector(pts[i]-pts[i-1])/90
             pt_radius = to_itype(radius, dbu)
             error_seg1 = False
             error_seg2 = False
+
+            #determine if waveguide does an S-Shape
+            if (sbends) and i < len(pts)-2:
+                angle2 = angle_vector(pts[i+2]-pts[i+1])/90
+                if angle == angle2 and dis2<2*pt_radius:  # An SBend may be inserted
+                    dis3 = pts[i+2].distance(pts[i+1])
+                    h = pts[i+1].y- pts[i].y if not (angle%2) else pts[i+1].x- pts[i].x
+                    theta = m.acos(float(pt_radius-abs(h/2))/pt_radius)*180/pi
+                    curved_l = int(2*pt_radius*sin(theta/180.0*pi))                  
+                    if (i > len(pts)-3 or i<3) and (dis1 < curved_l/2 or dis3 < curved_l/2): pass# Check if there is partial clearance for the bend when there is an end near
+                    elif (dis1 - pt_radius) < curved_l/2 or (dis3 - pt_radius) < curved_l/2: pass # Check if there is full clearance for the bend
+                    else:
+
+                      if not (angle%2):
+                        t = pya.Trans(angle, (angle == 2), pts[i].x+(angle-1)*int(curved_l/2), pts[i].y)  
+                      else:
+                        t = pya.Trans(angle, (angle == 1), pts[i].x, pts[i].y-(angle)*int(curved_l/2))
+                      bend_pts = pya.DPath(bezier_parallel(pya.DPoint(0, 0), pya.DPoint(curved_l*dbu, h*dbu), 0),0).to_itype(dbu).transformed(t)
+                      wg_pts += bend_pts.each_point()
+                      turn = 0
+                      i = next(it) #skip the step that was replaced by the SBend
+                      continue
+
             # determine the radius, based on how much space is available
             if len(pts) == 3:
                 # simple corner, limit radius by the two edges
@@ -402,7 +432,6 @@ def layout_waveguide2(TECHNOLOGY, layout, cell, layers, widths, offsets, pts, ra
                     if dis2/2 < pt_radius:
                         error_seg2 = True
                     pt_radius = min(dis1/2, dis2/2, pt_radius)
-
             if error_seg1 or error_seg2:
                 if not error_layer:
                     # we have an error, but no Error layer