Abstract

The main function of an optical buffer is to introduce a controllable delay to an optical signal in telecommunication networks. The possibility of continuously tunable optical buffering in coupled silicon waveguides by mechanical reconfiguration of the system has recently been proposed [1]. Here we present design and fabrication of such an optical buffer using III-V semiconductors. The buffer consists of two Indium Phosphide free-standing waveguides with optimal dimensions of 200 nm×300 nm separated by an air gap that can be varied in the range of ~50–500 nm. The device is designed to operate at a wavelength of 1550 nm. Due to the subwavelength size the waveguides support only the fundamental symmetric mode that is confined in both waveguides while the antisymmetric mode is below cut-off. Changing the size of the air gap varies the mode confinement within the waveguides and hence the effective refractive index of the structure, thus generating tunable optical delay to a propagating signal.

© 2015 IEEE