ANALYSIS OF AN INTERSECTIONAL OPTICAL SWITCH BY THE FINITE-DIFFERENCE BEAM-PROPAGATION METHOD

Three-dimensional (3-D) analysis of an intersectional optical switch is performed using the finite difference beam propagation method (FD-BPM), and design guidelines are obtained from this analysis. The operating characteristics of the switch are evaluated by extinction ratio and power attenuation in two output ports. The optimal structure parameters, such as normalized frequency (V), waveguide relative refractive index difference (Delta omega), and intersecting angle (theta), are obtained for 1.55 mu m wavelength operation. Wideband operation in the 1.3 to 1.6 mu m wavelength range is discussed taking into account the wavelength dispersion of materials. It is found that to achieve an extinction ratio that is better than 20 dB, a refractive index variation of 0.5 percent is enough for single-wavelength operation; however, a refractive index variation larger than 0.7 percent is required at the longer-wavelength side for wideband operation. Finally, the results of 2-D and 3-D analyses are compared and good agreement is obtained with an error of about 1 dB.