InP-based compact photonic crystal directional coupler with large operation range

Abstract

We present the design, fabrication and measurement of photonic crystal directional couplers in the InP/InGaAsP/InP material system. A comprehensive analysis of the dependence of the coupling length and usable wavelength range on the diameter of the holes next to the waveguides is given. The possibility to trade-off coupling length against usable wavelength range is shown. Designs with coupling lengths as low as 52 lattice constants and with an operation range covering 16% of the bandgap width are fabricated and measured. Good agreement between optimized and measured devices is achieved.