Recently, the technologies of optical fibers have been advanced and the special fibers, such as highly nonlinear fibers and photonic crystal fibers have been demonstrated. As the light sources, passively mode-locked ultrashort pulse fiber lasers have been commercialized and attracted a lot of attentions in several fields.
The group of author has been working on the development and applications of high performance ultrashort pulse fiber
lasers. In this paper, the recent progress of widely wavelength tunable ultrashort pulse and ultra wideband super
continuum generation by use of ultrashort pulse fiber laser are described.
In 1999, the widely wavelength tunable ultrashort soliton pulse generation has been demonstrated in the wavelength
region of 1.55 - 2.0 um. In this light source, it was difficult to generate the ideal ultrashort pulses in the wavelength
region around 1.55 um. Recently, we have demonstrated 1.0 - 1.7 um widely wavelength tunable ultrashort pulse
generation system by use of Yb doped fiber laser and photonic crystal fibers. Using this source, we can cover the whole
wavelength band used in optical communications.
In 2001, 1.0 - 2.0 um ultra wideband super continuum generation has been reported using ultrashort pulse fiber laser
and highly nonlinear fibers. In terms of the applications, the large noise and the fine structures become serious
problems. We have also analyzed the characteristics of super continuum generation and clarified the origin of noise and
fine structures. Recently, we have successfully generated the ultra wideband, low noise, ultraflat, and highly coherent
super continuum without any fine structures for the first time. Another novel super continuum generations are also