Specialty Optical Fibers Handbook

waveguide, the phase-matching condition is changed, resulting in the modulation

of the electric field in the fiber. Applied voltage V alters the refractive index n as

Dn ¼ (1=2)pn

3

lr(V=d), where r is the EO coefficient and d is the electrode’s gap.

The overplayed EO waveguides were reportedly using polymer [103–105],

lithium niobate crystal [106], liquid crystal [107, 108], and a GaAs/AlAs multiple

quantum-well waveguides [103, 109]. Figure 16.16 shows a wavelength and

switching response of this type of modulator [104]. A polished fiber half-coupler

was made from a standard single-mode 1.3-mm optical fiber and a 1.5-mm thick

corona poled EO polymer ...