Applications relating to telecommunications

In the case of the MZ interferometer (Fig. 3.11a), application of an electric field to one arm results in a phase retardation relative to the signal traversing 

As a consequence of the voltage-controlled destructive interference, the applied electrical signal is transduced onto the optical beam as an amplitude modulation. The birefringent modulator depicted in Eig. 3.11b functions as an electri-cal-to-optical signal transducer. Here, both TM and TE optical modes traverse 

Very successful efforts in employing polymeric materials as modulators have been made with the guest/host systems shovm in Table 3.7. The guest compounds are characterized by the cyanofuran moiety. A thermally rather stable host matrix, denoted as APC, is a copolymer poly[bisphenol A carbonate-co-4,4 -(3,3,5-trimethylcyclohexylidene)diphenol]. The systems shown in Table 3.7 are employed in commercially available modulators the relevant industrial companies are cited in Dalton s review article [5]. These polymeric systems are 

Pockels coefficients measured at the technologically important wavelengths 1.3 and 1.55 pm are higher than in the case of lithium niobate. Moreover, the difference in the dielectric constants is important s=2S (LiNb03) and =2.5-4 (EO polymer). The lower value corresponds to a decreased device power consumption and an enhanced speed of operation. 

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