IMPROVED PHOTONIC CRYSTAL DEVICE

摘要

There is disclosed an improved photonic crystal device (40), e.g. an optical coupler or coupling device, providing a photonic crystal waveguide means (44). Known taper coupling devices suffer from a number of problems such as excessive length and coupling losses. The invention seeks to provide an ultra-short taper, e.g. having a length of 5pm to l0pm or less. Accordingly the invention provides a photonic crystal device (40), providing a taper or optical transmission region (42) bounded by first and second photonic crystal (PhC) regions (43a,43b), first and second interfaces (46a, 46b) between the first and second photonic crystal regions (43a,43b) and the taper (42), respectively, being substantially continuous. By "substantially continuous" is meant that each interface (46a,46b) does not include any discontinuities, e.g. steps in a lattice of the regions (43a,43b).