ABSTRACT
This chapter discusses recent advances in femtosecond all-optical devices with a particular emphasis on ultrafast pulse generators and all-optical switches as basic devices for ultrafast systems. It describes the advantages of ultrafast all-optical devices and explains basic signal processing functions required for network systems. The chapter reviews recent progresses in typical all-optical devices by using prototype devices developed at Femtosecond Technology Research Association in Japan. They include ultrafast devices for mode-locked pulse generation, pulse compression and dispersion compensation, and several different types of all-optical switches using various device principles and ultrafast materials. The semiconductor monolithic laser structures are advantageous to generate pulses with transform-limited waveforms and a very high repetition rate owing to the very wide optical gain bandwidth and extremely short photon round trip time, which are characteristic of microcavity semiconductor laser structures. A semiconductor mode-locked laser basically consists of a gain medium and a saturable absorber placed within a waveguide cavity.
