Colorless directional coupler with dispersion engineered sub-wavelength structure.
Directional couplers are extensively used devices in integrated optics, but suffer from limited operational wavelength range. Here we use, for the first time, the dispersive properties of sub-wavelength gratings to achieve a fivefold enhancement in the operation bandwidth of a silicon-on-insulator directional coupler. This approach does not compromise the size or the phase response of the device. The sub-wavelength grating based directional coupler we propose covers a 100 nm bandwidth with an imbalance of ≤ 0.6 dB between its outputs, as supported by full 3D FDTD simulations.
Departamento Ingeniería de Comunicaciones, ETSI Telecomunicación, Universidad de Málaga, 29010 Málaga, Spain. robert.halir@ic.uma.es
R
R
Halir
A
A
Maese-Novo
A
A
Ortega-Moñux
I
I
Molina-Fernández
J G
JG
Wangüemert-Pérez
P
P
Cheben
D-X
DX
Xu
J H
JH
Schmid
S
S
Janz