INTEGRATED OPTICAL BEAM SPREAD TRANSFORMER

摘要

Beam spread transformers are required for chip-fibre couplings and must be polarisation-independent, show low losses and be economically produced. In a beam spread transformer (1) with an integrated structure having several buffer layers (5) mutually separated by conductive layers (6), an uncladded rib waveguide (7, 8) with a tapering area (9) is arranged on the top buffer layer (5). A section (11) over which the rib (8) extends is located between the interface (2) with the fibre and the tapering area (9). The waveguide layer (7) is completely removed from this section and the exposed buffer layer (5) is reduced to a width w2 which exceeds the width w1 of the continuous rib (8) in a symmetrical manner. The thus obtained additional rib (12) makes it possible for the coupling to be polarisation-independent and to be optimised with the increased heights (d1, d2, d3) thanks to the buffer layers (5).