Experimental Demonstration of Microring QPSK Modulators

Advanced optical modulation formats are a key technology to increase the capacity of optical communication networks. Mach­Zehnder modulators are typically used to generate various modulation formats. Here, we report the first experimental demonstration of quadrature phase-shift keying (QPSK) modulation using compact microring modulators. Generation of 20 Gb/s QPSK signals is demonstrated with 30 µmradius silicon ring modulators with drive voltages of ~6 V. These compact QPSK modulators may be used as building blocks to realize higher-level modulation formats in miniature optical transponders for high-capacity optical data links. ©2011 Optical Society of America OCIS codes: (250.5300) Photonic integrated circuits; (250.7360) Waveguide modulators; (060.5060) Phase modulation.