Ubiquitous Computing and Communication Journal
HIGH SPEED OPTICAL MODULATORS IN COMMUNICATIONS
M. Rakib Uddin1, M. Shah Alam2 and Yong Hyub Won1
1 School of Engineering, Information and Communications University (ICU)
Daejeon, South Korea.
2Department of Electrical and Electronic Engineering
Bangladesh University of Engineering and Technology (BUET)
In this paper, the microwave properties of coplanar waveguide (CPW) for Mach-
Zehnder electrooptic modulators in presence of asymmetry, has been presented by
using efficient and versatile finite element method (FEM). Two dimensional and
three dimensional electric field distributions, microwave effective
characteristic impedance, and microwave propagation losses of the modulator are
investigated in this work. We observed that the above properties are affected
significantly by the asymmetry of the CPW. We also observed that impedance
matching and phase velocity matching were changed significantly when the
modulator has asymmetry in its structure.
Keywords: Modulators, asymmetry, effective index, characteristic impedance.
Over the past decade, as the demand for
telecommunications services and bandwidth has
boomed, the need for and advantages of Mach-
transmission systems has been firmly established. In
higher speed digital communication applications,
fiber dispersion has limited system performance.
Mach-Zehnder external modulators provide both the
required bandwidth and the equally important means
for minimizing the effects of dispersion. Unlike
direct modulation of laser diode, Mach-Zehnder
external modulators can be designed for zero-chirp
or adjustable chirp operation. Zero-chirp or negative
chirp modulators help to minimize the system
degradation associated with fiber dispersion.
The frequency response of the broad-band Mach-
Zehnder Modulators with traveling wave electrode is