Optical switch mfr. comprising waveguide and heating element

摘要

The lower layer (13) is a phosphosilicate glass of thickness between 18 and 22 micrometres and the waveguides (15) is a germanophosphate glass of thickness between 6 and 8 micrometres. The concentration in these layers is then increased by heat treatment. A mask is formed on the waveguide and it is chemically attacked by a tetrafluoromethane and trifluoromethane mixture. The upper layer is a 10 to 18 micrometre layer of borophosphosilicate glass, including the waveguides and the heating element (21) has a thickness between 0.1 and 0.2 micrometres with a width of 12 to 16 micrometres in titanium and tantalum. These are overlaid by a second upper layer (23) of borophosphosilicate of 15 to 20 micrometres thickness.