A PHOTONIC SIGNAL TRANSMITTING DEVICE

摘要

A photonic signal transmitting device which comprises a first waveguide having a first core composed of a first material having a refractive index n1 and a second waveguide having a second core composed of a second material having an average refractive index n2>n1. The second core projects into the first core and is formed such that the effective refractive index of the device increases with progression into the second core from the first core. The effective refractive index of the device may be increased by forming the second core with a region which is tapered to provide an increasing cross-sectional area with progression into the second core. The effective refractive index of the device may additionally be increased by forming the second core such that its composition changes to increase the refractive index with progression into the second core.