Bend-Free Optical Power Transfer Using Photonic Crystal Waveguide Arrays

We report the study of 2-D photonic-crystal waveguide arrays (PCWA) composed of $N$ identical waveguides coupled evanescently with each other. The coupling properties of the waveguide modes are investigated using coupled-mode theory and finite-difference time domain method. One straightforward application of such an analysis is to route input power from a central waveguide to side waveguides. As a result, appropriate designs of PCWAs may permit the realization of efficient, compact and novel devices. For instance, we show that power dividers, switchers, and Mach–Zehnder interferometers can be feasible using $N =3$ channels. On the other hand, $N =5$ waveguides can divide the input power by 1/4 at a distance of approximately 37.2 $ \mu{\hbox {m}} $. Waveguide bends and Y-type junctions are used heavily for power transfer but they are prone to scattering losses; hence, lowering the transmission efficiency. They can be eliminated by means of PCWAs in the design of optical power distribution through photonic circuits.