Er-coupled Si nanocluster waveguide

Rib-loaded waveguides containing Er3+-coupled Si nanoclusters (Si-nc) have been produced to observe optical gain at 1535 mn. The presence of Si-nc strongly improves the efficiency of Er3+ excitation but may introduce optical loss mechanisms, such as Mic scattering and confined carrier absorption. Losses strongly affect the possibility of obtaining positive optical gain. Si-ne-related losses have been minimized to I dB/cm by lowering the annealing time of the Er3+-doped silicon-rich oxide deposited by reactive magnetron cosputtering. Photoluminescence (PL) and lifetime measurements show that all Er3+ ions are optically active while those that can be excited at high pump rates via Si-nc are only a small percentage. Er3+ absorption cross section is found comparable to that of Er3+ in Sio(2). However, dependence on the effective refractive index has been found. In pump-probe measurements, it is shown how the detrimental role of confined carrier absorption can be attenuated by reducing the annealing time. A maximum signal enhancement of about 1.34 at 1535 nm was measured.