Mesoporous sol-gel silica cladding for hybrid TiO2/electro-optic polymer waveguide modulators.

Yasufumi Enami,Alex K.-Y Jen,Yasuhisa Kayaba,Jingdong Luo

doi:10.1364/oe.22.016418

Abstract

We report the efficient poling of an electro-optic (EO) polymer in a hybrid TiO(2)/electro-optic polymer multilayer waveguide modulator on mesoporous sol-gel silica cladding. The mesoporous sol-gel silica has nanometer-sized pores and a low refractive index of 1.24, which improves mode confinement in the 400-nm-thick EO polymer film in the modulators and prevents optical absorption from the lower Au electrode, thereby resulting in a lower half-wave voltage of the modulators. The half-wave voltage (Vπ) of the hybrid modulator fabricated on the mesoporous sol-gel silica cladding is 6.0 V for an electrode length (Le) of 5 mm at a wavelength of 1550 nm (VπLe product of 3.0 V·cm) using a low-index guest-host EO polymer (in-device EO coefficient of 75 pm/V).

Highlights

The electro-optic (EO) polymer has considerable advantages because of its wide bandwidth and low driving voltage, which result from its low dielectric dispersion and high EO coefficient
We report the efficient poling of an electro-optic (EO) polymer in a hybrid TiO2/electro-optic polymer multilayer waveguide modulator on mesoporous sol-gel silica cladding
The half-wave voltage (Vπ) of the hybrid modulator fabricated on the mesoporous sol-gel silica cladding is 6.0 V for an electrode length (Le) of 5 mm at a wavelength of 1550 nm (VπLe product of 3.0 V·cm) using a low-index guest-host EO polymer

Summary

Introduction

The electro-optic (EO) polymer has considerable advantages because of its wide bandwidth and low driving voltage, which result from its low dielectric dispersion and high EO coefficient. Si modulators have been extensively studied for on-chip optical interconnections in CMOS circuits Their performance still requires additional improvement of the half-wave voltage, bandwidth and optical insertion loss, many reports of Si modulators have recently shown a VπL of 2-3 V·cm with a 3 dB bandwidth of 100 GHz. Mesoporous sol-gel (MPSG) silica has been used for various applications, such as low-k materials [11], using the standard template method. The low-index cladding in the bottom cladding increased the mode confinement in the hybrid TiO2/EO polymer multilayer waveguide modulators, which was shown from the Vπ measurements and lower optical insertion loss in TiO2/EO polymer multilayer slot waveguide modulators

Design and fabrication of modulators on mesoporous sol-gel silica

Vπ measurement for the EO modulator

Conclusion