Abstract

Planar waveguide amplifiers are one of the key components of integrated optic devices. The integration of amplifiers together with other optical components such as splitters, couplers, and wavelength division multiplexers, enables many optical functions to work together on a single chip without optical losses. Erbium is used as an optically active element in waveguide amplifiers because of its intra-4f transition around 1.54 μm, a standard telecommunications wavelength. Advantages of erbium-doped amplifiers are the linear gain response, temperature and polarization insensitivity, and low noise.¹ In order to achieve high gain values on the centimeter length scale of an optoelectronic integrated circuit, Er concentrations in the at.% range are needed. At such high Er doping levels, concentration quenching effects, such as cooperative upconversion, can affect the gain performance of the amplifier. By using relatively low Er concentrations in long waveguides (up to 50 cm), optical gain has been obtained in silica-based planar devices.^2,3,4,5 However, because of the large optical mode dimensions of these devices, high pump powers (≈ 100 mW) are necessary to reach net gain. In addition, due to their large waveguide bending radius (≈ cm) these amplifiers take up a large area on a planar substrat.

© 1996 Optical Society of America