We model a laterally coupled Franz-Keldysh add-drop ring modulator designed to overcome the C-band indirect absorption of silicon-germanium. Although our concept is based on loss-sensitive interferometry, it utilizes the same highly absorptive germanium-rich compositions geared toward complementary metal-oxide semiconductor (CMOS) photodetectors and electroabsorption modulators. The proposed device can be integrated with passive waveguide networks in which the carrier plasma modulation mechanism is ineffective. In addition, unlike previous silicon-germanium modulator schemes, complex butt-coupling between the passive transport and the active silicon-germanium waveguides is not required. Instead, the optical mode remains guided within the transport waveguide, minimizing transition losses.
© 2012 Optical Society of America
Original Manuscript: February 7, 2012
Revised Manuscript: March 5, 2012
Manuscript Accepted: March 6, 2012
Published: April 27, 2012
Peng Huei Lim, Jingnan Cai, Yasuhiko Ishikawa, and Kazumi Wada, "Laterally coupled silicon-germanium modulator for passive waveguide systems," Opt. Lett. 37, 1496-1498 (2012)