Integrated-optical amplifier made of solid-state active materials

A new integrated-optical amplifier, based on the use of a passive waveguide on a substrate made of an active material, is proposed. The amplification involves an evanescent (in a transverse direction) wave propagating in the substrate. An experimental investigation is reported of a planar amplifier with a substrate made of an LiF crystal containing F₂^– colour centres and a fused quartz film, 1.9 μm thick. The results indicate that the gain can be up to 10 dB for 1.15 μm signal radiation when the crystal is pulse-pumped with 1.064 μm radiation.