Concepts for optical waveguide switches in silicon

Abstract

By time domain measurements on a carrier injection switch using Ge-indiffused waveguides in silicon the plasma dispersion and the thermo-optical effect were separated and quantified. Optimized thermo-optical switches in silicon-on-insulator with low switching powers are also presented. Intro duct ionSilicon is a highly developed and inexpensive material and it offers a large potential for low cost optical devices. Due to the micromechanical properties for instance silicon can be used for optical motherboards as well as for automatic fiber-chip coupling by etched V-grooves.The goal of our research is the development of optical components in silicon which are compatible to the standard Si-technology in order to take advantage of existing production lines. Since the electric-field effects (Kerr-effect, "electro-refraction" and "electro-absorption") in silicon are too small for efficient devices [1], only the plasma dispersion effect [2] 21 3 \=1.3m: -=-1.41•1O cm (1) and the thermo-optical effect (-= +2 . iO' K [3]) are promising candidates for the realization of optical waveguide switches in silicon (n: refractive index, N: carrier concentration, T: temperature, ,\: wavelength). In this work we will discuss a carrier injection switch based on a singlemoded Ge-indiffused waveguide. Similar to [2,4] the carrier injection switch shows the coexistence of the plasma dispersion and the thermo-optical effect, since the necessary injection current causes electrical losses and therefore heat. By analyzing the switch characteristics in time domain both 332 ISPIE Vol. 2449 O-8194-1800-5/95/$6.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/24/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx