band. IS-modulator technology is being investigated to further improve modula-
tion efficiency and/or reduce the length of high-speed light-intensity modulators,
and the experimental work has been focused on the quality of the heterostructure
interfaces as this will determine the limits of the possible reduction in required
drive voltage. Calculations based on the present status of the development of
epitaxial growth indicate that the voltage swing for 10-dB optical extinction
ratio may be expected to be below 1 V
p-p
for a bitrate of 100 Gb/s. IS is treated
in more detail in Section 7.7 of this chapter.
7.7 NOVEL TYPES OF MODULATORS
7.7.1 Intersubband Electroabsorption Modulators
The QCSE-based interband EAM described in Sections 7.5 and 7.6 constit ...