Porous silicon micromachining to position optical fibres in silicon integrated optical circuits

Low-loss optical fibre connections require deep grooves etched in silicon s ubstrate for accurate fibre positioning. As shown in this paper these groov es can be obtained by using localised formation of porous silicon on patter ned substrates. Cr-Au masking layer with a duration in HF solution longer t han 30 min is used to fabricate grooves with a depth higher than 75 mu m. N +-type silicon provides grooves with a pseudo-V shape which is compatible w ith accurate fibre alignment. By using this technology, arrays of optical f ibres are positioned with an accuracy higher than 1 mu m.