Rare earth-doped confined structures for amplifiers and lasers

Here, we present an overview of the specific spectroscopic properties of fluoride planar waveguides which emphasize the difference between rare earth-doped waveguide and bulk and demonstrate their potentiality to be used as lasers and amplifiers. We illustrate this with recent results obtained at strategic wavelengths for telecommunications. Furthermore, we are dealing with even more confined structures such as optical microcavities that are resonators in which at least one of the dimensions is of the order of the optical wavelength. These structures enable to control the spontaneous emission properties of rare-earth doped materials placed inside them. (C) 2000 Elsevier Science S.A. All rights reserved.