A tapered light wave guide reduced in propagation loss, improved in coupling efficiency and free from the problem of optical damage. An input section, a widthwise tapered coupling section having a depth d2, and a wave guide having a depth d1 are formed on an LiNbO.sub.3 substrate. A depthwise tapered...http://www.google.de/patents/US5142596?utm_source=gb-gplus-sharePatent US5142596 - Tapered light wave guide and wavelength converting element using the same
