Towards An Er-Doped Si Nanocrystal Sensitized Waveguide Laser — The Thin Line Between Gain And Loss

Abstract

Current Er-doped planar waveguide amplifiers and lasers make use of a pump laser emitting at 0.98 μm that excites Er3+ ions into their second excited state (4I11/2). From this level, the ions quickly relax non-radiatively to the long-lived first excited state (4I13/2) providing the population inversion necessary for gain (see Figure l(a)). For an Er doped waveguide laser, this means an accurately tuned semiconductor pump laser needs to be integrated with an optical waveguide. This is an expensive approach, since it requires an expensive pump laser and involves a difficult alignment procedure to obtain optimum coupling between pump laser and waveguide. If the pump laser could somehow be eliminated from this scheme, the fabrication of low-cost Si based Er doped optical amplifiers and lasers operating at 1.5 μm would become a real possibility. This is exactly what co-doping with Si nanocrystals promises to do.