A compact and low-driving-voltage silicon electro-absorption modulator utilizing a Schottky diode operating up to 13.2 GHz in C-band

Abstract

This paper demonstrates the workings of 1 Vpp low-driving-voltage silicon electroabsorption modulator (EAM) utilizing a Schottky diode. Optical modulation using a schottky diode was achieved by intensity change of the guiding light due to the free-carrier absorption in the semiconductor to change its absorption coefficient, not conventional interference effects. The proposed EAM consists of a lateral metal-semiconductor junctions that helps to maximize the free carrier injection and extraction by a Schottky contact on the rib waveguide. In order to achieve high speed operations, travelling-wave type electrodes were designed. The fabricated EAM demonstrates a broad operational wavelength range of 50 nm for C-band with a uniform extinction ratio (ER) of 3.9 dB, even for a compact 25 μm modulation length with 1 Vpp driving voltage. Also, the travelling-wave type electrodes enabled the modulator operating up to 26 GHz with 13.2 GHz of 3-dB electrooptic bandwidth, experimentally.