Broadband polarization-insensitive optical switch on silicon-on-insulator platform

A novel configuration for realizing a polarization-insensitive optical switch on silicon-on-insulator of 340nm-thick top-silicon layer is demonstrated, using submicron sized waveguides. The device is based on the Mach-Zehnder interferometer structure. By carefully designing the 3dB couplers and the delay-line waveguides in the device, it is possible to achieve a similar switching behavior for all polarizations. Theoretical analyses indicate that extinction ratios of better than -25dB and insertion losses of better than -0.6dB can be obtained simultaneously for transverse-electric and transverse magnetic polarized modes in the whole C-band. Experimental results also confirm the polarization-insensitive property of the proposed optical switch. Extinction ratios of about -15dB are measured for both polarizations.