WAVES AND VIBRATIONS IN INHOMOGENEOUS STRUCTURES ...

4.2 Photonic crystal building blocks 37
Figure 4.4 Compound structure illustrating the optimized building blocks for photonic
crystal waveguides optimized in papers [12]–[14]. From left to right are seen: a 120-degree
bend with 5 optimized holes near the outer bendregion, a Y-splitter and a 60-degree bend.
a) b)
14
Bend loss (dB)
c)
12
10
8
6
4
2
fig. a)
fig. b)
0
1250 1300 1350 1400 1450 1500
Wavelength (nm)
Figure 4.5 a) Fabricated un-optimized structure, b) Topology optimized (double) 90degree
photonic crystal waveguide bend, c) Measured bend loss for the two structures.
From paper [15].