We have developed a single mode fiber-light source at 1.8um band, which composes of thulium (Tm)-doped silica fiber
and optical devices used in telecommunication fields. This laser can be operated as a laser and broadband light source
selectively. The laser wavelength is tuned from 1765nm to 1812nm by adjusting an angle of a built-in band pass filter
(BPF). A maximum output power is 115mW at 1812nm, in the case that pump power is 363mW. The broadband light
source has a maximum power of 10mW, the peak wavelength of 1840nm and the full width at half maximum of 50nm.
By using these light sources, we have succeeded in obtaining images of test target by observing reflected light through