Chirped grating lenses on Nb_2O_5 transition waveguides

Efficient tapered Nb2O5 transition waveguide obtained by reactive sputtering has been demonstrated experimentally. It provides effective interconnection between two sections of Ti-indiffused waveguide with 0.8-dB total insertion loss. Chirped grating lenses have also been fabricated on Nb2O5 waveguides that have yielded 85% throughput efficiency. For signal processing applications in Ti-indiffused waveguides, the combination of grating lenses and the Nb2O5 transition waveguide will allow us to obtain lens functions that have both high efficiency and large angular field of view (∼4°).