Polymerization module

Fig. 35. Pacific Wave Industries 40-GHz polymeric modulator. PWI also offers a version that is designed for 100-GHz operation...

The application potential of the effects dealt with in this chapter covers a broad field extending from specific electro-optical devices to the all-optical computer. For many applications, polymeric materials have proven appropriate and equivalent to inorganic materials. This section is focused on two aspects, the electro-optical (EO) or Pockels effect and two-photon absorption, which have been exploited extensively. Technical developments relating to polymeric modulators operating on the basis of the Pockels effect have reached the stage of commercialization [5]. 

Tumolillo, T. A., Jr., and Ashley, P. R., Fabrication techniques of photopolymer clad waveguides for nonlinear polymeric modulators, SPIE Proc. Photopolym. Device Phys. Chem. Appl. II, 1559 (1991), 65,... 

In summary, polymeric EO and semiconductor VLSI circuitry can be integrated without degradation of the performance of either circuitry, and operation of polymeric modulators can be easily accomplished up to the frequency limitation of MMIC circuitry. 

The three most common basic configurations of polymeric modulators are the Mach-Zehnder interferometer, the birefringent modulator, and the directional cou-... 

FIGURE 30 Schematic of horizontal and vertical integration of polymeric modulators with VLSI semiconductor electronics. 

TACAN Corporation (Carlsbad, CA) has investigated the use of both Mach-Zehnder and birefringent polymeric modulators for CATV applications. A carrier-to-noise ratio of 53 dB and 80-channel television transmission have been demonstrated using packaged polymer modulators [110]. A similar demonstration has been made by researchers at IBM. TACAN researchers have also investigated long-term half-wave... 

Other demonstrated prototype devices include optical gyroscopes (144), broadband acoustic spectrum analyzers (145), 1x2 Y-fed directional couplers (146) and polarization-insensitive electrooptic modulators (147,148). For long-haul telecommimication applications, it is difficult to maintain polarization control thus, a need exists for polarization-insensitive modulators. Indeed, polarization insensitivity was one of the advantages claimed for gallium arsenide elec-troabsorptive modulators. By using different poling schemes, overall polarization insensitivity has been achieved for polymeric modulators (147,148). 

Processing issues The integration of polymeric modulators with silica fibers and VLSI electronic circuitry. 

We have carried out extensive investigations of the sources of poling induced optical loss and of losses associated with the fabrication of buried channel waveguide structures and the intergration of polymeric modulator waveguides with silica optical fibers. 

Recently, optical loss due to optical mode size mismatch between polymer EO waveguide modes and silica frber modes have been dramaticaUy reduced exploiting reactive ion etched tapered transitions (5). This achievement together with the demonstration of integration of polymeric electro-optic circuitry with VLSI semiconductor electronics (6) and very large polymeric modulator bandwidths (7) represent dramatic advances in the utilization of lymeric electro-optic materials. 

---