Abstract

The limitations of current semiconductor or lithium niobate based technologies in terms of efficiency, integrability, and cost can be surpassed by calling on the remarkable properties of functionalized polymers.^1,2 The major asset of this new family of materials is the unlimited flexibility of potentially available structures resulting from a predictive molecular engineering approach. Furthermore, adequately defined processing technologies are compatible with hybrid polymer/ semiconductor integration. In that perspective, the fabrication of unimodal polymer based low loss buried strip waveguides have been achieved by classical photolithographic and dry etching techniques (Reactive Ion Etching).^3,4 Passive functions such as optical combiners or splitters have thus been obtained with a polystyrene core waveguide exhibiting propagation losses of the order of 1dB/ cm. Such a polymer based waveguide has been monolithically integrated with a Buried Ridge Structure (BRS) laser.⁵ (Figure 1a) The light output power as measured at the cleaved laser facet and compared to that emitted at the waveguide end, displays only 4 dB attenuation (Figure 1b). The laser cavity and the waveguide are respectively 250 µm and 600 µm long. The laser threshold current is 15 mA and the optical power output from the laser and the waveguide facets were respectively 11 mW and 5 mW at 100 mA. Significant improvements are expected from polymeric materials with even lower loss figures and optimization of the processing steps. The integrated device shows high thermal stability, with no significant decrease in the waveguide power output after heating at 250°C for 1h.

© 1995 IEEE