Towards High-Power Ultrafast Short-Wavelength-Band Tm-Doped Fiber Laser

Tm-doped silica fiber features a broad fluorescence spectrum of ∼500 nm ranging from $1.6\ \mu\mathrm{m}$ to $2.2\ \mu\mathrm{m}$ [1]. Most research to date has been focused on the long-wavelength band, which is around $2\ \mu\mathrm{m}$ , while the short-wavelength-band is far less investigated. However, this wavelength band is of great importance for applications such as extending conventional communication bands, transparent plastic welding, laser surgery and bioimaging. The main reason for the lack of investigation on the short-wavelength-band is its significantly lower gain. This originates from the low emission cross-section of Tm-doped silica fiber, as well as the reabsorption effect due to its quasi-three energy level structure. Only in recent years, through suppression of high gain at a longer wavelength, more and more research efforts are focused on the short-wavelength-band operation of Tm-doped fiber laser and amplifier.