Abstract

Direct writing by femtosecond laser pulses is an innovative technology for fabrication of optical waveguides in glasses [1]. It is a simple and low cost technique, that avoids photolithographic processes and allows 3D fabrication capabilities. In the last few years, the quality of femtosecond laser written waveguides has shown a substantial improvement. In particular, high quality active waveguides have been produced culminating in the demonstration of cw waveguide lasers on a commercial Er:Yb:phosphate glass (Kigre Inc., mod. QX) [2], Recently, a great effort has been devoted to passive mode-locking of waveguide lasers, because of their inherent simplicity and compactness. Such lasers will provide low-noise and inexpensive light sources for applications in optical communications, optically sampled analog-to-digital converters, and spectral line-by-line pulse shaping for arbitrary optical waveform synthesis. On the other hand, single-frequency lasers at 1.5 μm are essential tools for a variety of applications in spectroscopy, optical communications, and optical sensing with requirements that may become extremely demanding in terms of power, compactness, insensitivity to environmental disturbance, and high temporal coherence.

© 2007 IEEE