Abstract Using a photonic crystal array, an all-optical
half-subtractor has been designed that consists of four
resonant rings and some waveguides which connect two
input ports to output ports. The silicon rods with a period
of 0.631 μm are arranged in the form of a square.
Concerning the four working states of the device,
different radii of nonlinear rods inside the resonators
have been chosen. This issue makes the different
switching thresholds for the rings and results in the
correct dropping operation for optical waves. Unlike the
previous works, each bit is defined to one port, and the
input ports have equal power. The maximum rise time
and the contrast ratio of the presented circuit are 3.5 ps
and 8.45 dB, respectively. The fast response and small
size are the main advantages of the presented subtractor.
The obtained results demonstrates that the designed
device has an acceptable performance which is proper for
optical applications. تفاصيل المقالة