
273III-Nitride Semiconductors: New Infrared Intersubband Technologies
8.4 ELECTRO-OPTICAL MODULATORS
Electro-optical amplitude and phase modulators allow tuning the amplitude, phase,
and/or polarization state of an optical beam as a function of the control voltage.
State-of-the-art technologies in this eld include modulators based on the quantum-
conned Stark effect of interband transitions in InGaAsP QWs [158] and on the
electro-optical effect in materials like LiNbO
3
within a Mach-Zehnder conguration
[159]. These devices present several drawbacks, such as low saturation power and
positive chirp in the former case and the need for high d