Low-voltage electro-optic polymer modulators

Electro-optic (EO) polymer modulators have demonstrated high speed external modulation of optical signals. Additionally, EO polymers have closely matched refractive indices at optical and microwave wavelengths, which enables high bandwidth operation. An EO polymer includes a polymer matrix and an organic "push-pull" chromophore that can be modified to give poled polymers with high EO activity. This high EO activity and optical-microwave velocity match offer the promise of accomplishing broadband, high speed optical modulation with low drive voltage. Such optical signal modulation is critical for applications in phased array radar and RF photonics. However, practical fabrication of optical modulators that realize the potential of EO polymers requires clad materials with optimized properties such as conductivity, dielectric constant, optical loss, and refractive index. In addition, other practical issues such as electrode design, optical fiber coupling, and hermetic packaging are critical in final device performance. We report on high-speed electrode parameters as well as electro-optic performance versus frequency of modulators fabricated on 6" silicon wafers. The r₃₃ values measured on single layer thin films are compared with those resulting from V_π measurements on devices. We compare the effect of EO polymer morphology on device fabrication and optical loss for different EO polymers.