No abstract

Electro-optic side-chain polymers have been synthesized by the post-functionalization of methacrylate isocyanate polymers with novel phenyl vinylene thiophene vinylene bridge (FTC) nonlinear optical chromophores. For this application, FTC-based chromophores were modified in their electronic donor structure, exhibiting much larger molecular hyperpolarizabilities compared with the benchmark FTC. Of these new chromophores, absorption spectra, hyper-Rayleigh scattering experiment, and thermal analysis were carried out to confirm availability as effective nonlinear optical units for electro-optic side-chain polymers. The electro-optic coefficients (r 33 ) of obtained polymers were investigated in the process of in situ poling by monitoring the temperature, current flow, poling field, and electro-optic signal. Compared with the non-substituted analogue, benxyloxy modified FTC chromophore significantly achieved higher nonlinear optical property, exhibiting molecular hyperpolarizability at 1.9 lm of 4600 Â 10 À30 esu and an r 33 value of 150 pm/V at the wavelength of 1.31 lm. Synthesized electro-optic polymers showed high glass transition temperature (T g ), so that the temporal stability examination exhibited >78% of the electro-optic intensity remaining at 85 C over 500 h. INTRODUCTIONDuring the past several decades, there has been growing interest in organic and polymeric electro-optic (EO) materials due to their potential applications in telecommunication, digital signal processing, THz generators, and photonic nano-micro devices. 1-5 This trend of increasing interest continues in the development of a significantly high EO coefficient (r 33 ); higher than 100 pm/V at telecommunication wavelengths. Such high EO performance has allowed for Mach-Zehnder modulators with low driving voltage of <1 V, which makes this class of devices very attractive for high-bandwidth operation. These devices have shown optical modulations up to 100 GHz in commercial devices and up to 1.6 THz experimentally. 6-9 Such performance has demonstrated EO activity 10 times that of the inorganic counterparts (LiNbO 3 : r 33 $ 32 pm/V).

No abstract

Ultra-thin silicon and electro-optic (EO) polymer hybrid waveguide modulators have been designed and fabricated. The waveguide consists of a silicon core with a thickness of 30 nm and a width of 2 μm. The cladding is an EO polymer. Optical mode calculation reveals that 55% of the optical field around the silicon extends into the EO polymer in the TE mode. A Mach-Zehnder interferometer (MZI) modulator was prepared using common coplanar electrodes. The measured half-wave voltage of the MZI with 7 μm spacing and 1.3 cm long electrodes is 4.6 V at 1550 nm. The evaluated EO coefficient is 70 pm/V, which is comparable to that of the bulk EO polymer film. Using ultra-thin silicon is beneficial in order to reduce the side-wall scattering loss, yielding a propagation loss of 4.0 dB/cm. We also investigated a mode converter which couples light from the hybrid EO waveguide into a strip silicon waveguide. The calculation indicates that the coupling loss between these two devices is small enough to exploit the potential fusion of a hybrid EO polymer modulator together with a silicon micro-photonics device.

No abstract