In 6G and beyond 6G network systems, the radio-over-fiber (RoF) technology that transmits signal waveforms of terahertz waves using optical fibers is attracting much attention. In the receivers of the radio sections of the mobile fronthaul and the remote antennas in the RoF systems, there is a need to develop low-cost, high-performance devices that convert wireless signals to optical signals. Organic electro-optic (EO) polymers can have large EO coefficients compared with nonlinear optical crystals such as lithium niobate (LiNbO3) and realize ultra-high-speed optical modulation of several hundred GHz or more. It is expected to realize devices that directly convert terahertz signals into optical signals by using the EO polymers. We will show research activities on new Information and Communication Technology (ICT) devices enabled by organic electro-optic polymers.