PROCEEDINGS ARTICLE | August 9, 2007
Proc. SPIE. 6731, International Conference on Lasers, Applications, and Technologies 2007: Advanced Lasers and Systems
KEYWORDS: Optical lithography, Channel waveguides, Waveguides, Etching, Silicon, Gases, Aluminum, Erbium, Reactive ion etching, Chlorine
Reactively co-sputtered amorphous Al2O3 waveguide layers with low propagation losses have been deposited. In order to define channel waveguides in such Al2O3 films, the etching behaviour of Al2O3 has been investigated using an inductively coupled reactive ion etch system. The etch rate of Al2O3 and possible mask materials was studied by applying various common process gases and combinations of these gases, including CF4/O2, BCl3, BCl3/HBr and Cl2.
Based on a comparison of the etch rates and patterning feasibility of the different mask materials, a BCl3/HBr plasma and
and standard resist mask were used to fabricate channel waveguide structures. The etched structures exhibit straight
sidewalls with minimal roughness and etch depths of up to 530 nm, sufficient for defining waveguides with strong
optical confinement and low bending losses. Low additional propagation losses were measured in single-mode Al2O3 ridge waveguides defined using the developed etch process. In initial investigations, Al2O3:Er layers fabricated using the same deposition method applied for the undoped layers show typical emission cross-sections, low green upconversion luminescence and lifetimes up to 7 ms.
