Title :
Scaling the modulation bandwidth and phase efficiency of a silicon optical modulator
Author :
Liu, Ansheng ; Samara-Rubio, Dean ; Liao, Ling ; Paniccia, Mario
Author_Institution :
Photonics Technol. Lab., Intel Corp., Santa Clara, CA, USA
Abstract :
We present an optimized design and detailed simulation of an all-silicon optical modulator based on a silicon waveguide phase shifter containing a metal-oxide-semiconductor (MOS) capacitor. Based on a fully vectorial Maxwell mode solver, we analyze the modal characteristics of the silicon waveguide. We show that shrinking the waveguide size and reducing gate oxide thickness significantly enhances the phase modulation efficiency because of the optical field enhancement in the voltage induced charge layers of the MOS capacitor, which, in turn, induce refractive index modulation in silicon due to free carrier dispersion effects. We also analyze the device speed by transient semiconductor device modeling. As both optical absorption and modulation bandwidth increase with increasing doping concentration, we show that, with a nonuniform doping profile in the waveguide, balance between the device operation speed and optical loss can be realized. Our simulation suggests that a TE-polarized optical phase modulator with a bandwidth of 10 GHz and an on-chip optical loss less than 2 dB is achievable in silicon.
Keywords :
MOS capacitors; doping profiles; integrated optics; light polarisation; optical design techniques; optical dispersion; optical losses; optical modulation; optical phase shifters; optical waveguides; phase modulation; refractive index; semiconductor device models; silicon; silicon-on-insulator; 10 GHz; Si; TE-polarized modulator; device operation speed; doping concentration; free carrier dispersion effects; fully vectorial Maxwell mode solver; metal-oxide-semiconductor capacitor; modulation bandwidth; modulation bandwidth scaling; nonuniform doping profile; on-chip optical loss; optical absorption; optical field enhancement; optical loss; optical phase modulator; optimized design; phase efficiency; phase modulation efficiency; phase shifter; planar lightwave circuits; reducing gate oxide thickness; refractive index modulation; silicon optical modulator; silicon waveguide; transient semiconductor device modeling; voltage induced charge layers; Bandwidth; Doping profiles; MOS capacitors; Optical devices; Optical modulation; Optical refraction; Optical variables control; Optical waveguides; Phase modulation; Silicon; Metal-oxide-semiconductor (MOS) capacitor; optical modulator; phase shifter; planar lightwave circuits; silicon photonics; silicon-on-insulator (SOI); waveguide;
Journal_Title :
Selected Topics in Quantum Electronics, IEEE Journal of
DOI :
10.1109/JSTQE.2005.845618