ABSTRACT
CONTENTS 5.1 Introduction ........................................................................................................................ 174 5.2 Configurations of MEMS VOAs ....................................................................................... 177
5.2.1 Direction-Coupling-Type MEMS VOA ................................................................ 177 5.2.2 Interference-Type MEMS VOA ............................................................................. 178 5.2.3 Diffraction-Type MEMS VOA ............................................................................... 179 5.2.4 Refraction-Type MEMS VOA................................................................................. 182 5.2.5 Reflection Type of MEMS VOAs ........................................................................... 183
5.3 Specifications of Different MEMS VOA Configurations .............................................. 186 5.4 Optical Attenuation Model of Single-Shutter VOA ....................................................... 190
5.4.1 General Model ......................................................................................................... 191 5.4.2 Far-Field Attenuation Model ................................................................................. 193 5.4.3 Near-Field Attenuation Model .............................................................................. 196
5.5 Optical Model and Tuning Schemes of Dual-Shutter VOA ......................................... 199 5.5.1 Attenuation Model .................................................................................................. 199 5.5.2 Analysis of Linear Tuning Schemes ..................................................................... 201 5.5.3 Analysis of Tuning Resolution ..............................................................................203
5.6 Analyses of Temperature, Wavelength, and Polarization Dependencies ..................206 5.6.1 Temperature-Dependent Losses ...........................................................................206 5.6.2 Wavelength-Dependent Losses .............................................................................208 5.6.3 Polarization-Dependent Losses ............................................................................209
5.7 Experimental Studies of MEMS VOAs ............................................................................ 211 5.7.1 Surface-Micromachined Single-Shutter VOAs ................................................... 211
