A ribbed structure (60a), co-operating with an unribbed surface of a coupling element 64, is employed to introduce microbending in an optical fibre (51) intermediate its two ends with a periodicity which couples the fundamental bound mode of the fibre into a cladding mode from which optical power is...http://www.google.fr/patents/US4898442?utm_source=gb-gplus-shareBrevet US4898442 - Non-intrusive fibre optic tap
