Broadband waveguide intersection with low crosstalk in two-dimensional photonic crystal circuits by using topology optimization

Abstract

Topology optimization has been used to design intersections in two-dimensional photonic crystal slab waveguides. We have experimentally confirmed that the optimized intersection displays high-transmittance with low-crosstalk for the straightforward beam-propagation line.

Subwavelength grating: A new type of microphotonic waveguide and implementations to fiber-chip coupling, waveguide crossing and refractive index engineering

“…3b), the loss is decreased by a factor of >30. This is among the lowest loss and minimal polarization dependence yet reported for crossings in high index contrast waveguides [5]- [7]. Unlike the latter, our waveguide crossing is a binary structure and it is fabricated using a single etch step.…”

Evolution of nanophotonics from semiconductor photonic crystal device to metal/semiconductor plasmonic device

“…The TO design has so far been applied to intersection [11], bend [12], wavelength-selective Y -junction [13] and DC waveguides. The TO method is effective for designing the wavelength sensitive Y-junction also, as shown in Fig.…”

Topology optimization of waveguide bends with wide, flat bandwidth in air-bridge-type photonic crystal slabs

“…This method has proven effective in drastically improving the bandwidth and transmittance of various components in 2D PC waveguides, such as bends, 16,17 branches, 18 and intersections. 19 However, the TO design of bends reported in Ref. 17 was performed for the target frequency of the leaky mode and is thus not suitable for large-scale PC slabs in which the propagation loss of straight waveguides is considerable.…”

“…19 It has a photonic band gap for the TE mode ͑in-plane electronic field͒ in the normalized frequency range 0.238c / a to 0.319c / a, where c is the speed of light in vacuum. The waveguide is formed by eliminating one line of air holes, as shown in the inset of Fig.…”