| 摘要 |
A waveguide structure according to the invention comprises a core layer ( 10 ), having a refractive index n<SUB>core</SUB>, and an array of rods ( 11 ) in the core layer having a refractive index n<SUB>rods</SUB>. The refractive indices satisfy the inequality: n<SUB>rods</SUB>>n<SUB>core</SUB>. In a planar waveguide structure buffer ( 12 ) and cladding ( 13 ) layers are included, having a refractive index n<SUB>buffer </SUB>and n<SUB>cladding </SUB>respectively. The refractive indices then satisfy the inequality: n<SUB>rods</SUB>>n<SUB>core</SUB>>n<SUB>cladding </SUB>and n<SUB>buffer</SUB>. This condition provides greater vertical confinement of the E-field of an optical signal passing through the waveguide. Furthermore, it allows waveguides to be formed of a glassy material having a similar refractive index and core dimensions to that of a fiber. A high refractive index contrast within the photonic crystal region is used while totally eliminating the need for mode conversion to launch light in and out of the waveguide.
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