Optimization of efficiency-loss figure of merit in carrier-depletion silicon Mach-Zehnder optical modulator

• Published in: Optics express Vol. 21; no. 17; pp. 19518 - 19529
• Main Authors: Goykhman, Ilya, Desiatov, Boris, Ben-Ezra, Shalva, Shappir, Joseph, Levy, Uriel
• Format: Journal Article
• Language: English
• Published: United States 26.08.2013
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/oe.21.019518

In this paper we study the optimization of interleaved Mach-Zehnder silicon carrier depletion electro-optic modulator. Following the simulation results we demonstrate a phase shifter with the lowest figure of merit (modulation efficiency multiplied by the loss per unit length) 6.7 V-dB. This result was achieved by reducing the junction width to 200 nm along the phase-shifter and optimizing the doping levels of the PN junction for operation in nearly fully depleted mode. The demonstrated low FOM is the result of both low V(π)L of ~0.78 Vcm (at reverse bias of 1V), and low free carrier loss (~6.6 dB/cm for zero bias). Our simulation results indicate that additional improvement in performance may be achieved by further reducing the junction width followed by increasing the doping levels.