Diode-Pumped Tm3+-Doped Sesquioxide Ultrashort Pulse Seed Oscillators for Ho-Amplifiers

To date, demonstrated ultrashort pulse seed sources for Ho
³⁺
-doped amplifiers, such as Ho:YAG and Ho:YLF, leave a lot to be desired in terms of complexity, cost, and efficiency. Sources like those used in [1] involve nonlinear energy transfer schemes, requiring numerous stages before a pulse covering a suitable spectral range (Ho:YAG, 2090 nm; Ho:YLF, 2050/2060 nm) is generated. The more direct approach of using a Ho:fiber laser, as reported in [2], benefits from a less complex setup. However, the requirement of multiple pump stages inevitably reduces the systems overall efficiency in addition to increasing the cost. A clear route for reducing the overall cost and complexity of such ultrashort pulse seed sources would be to employ a gain medium that could utilise direct diode pumping as well as being able to target the gain spectra of existing Ho
³⁺
-doped amplifiers. Here we report on our recent developments of diode-pumped ultrashort pulse Tm
³⁺
-doped Lu
₂
O
₃
and LuScO
₃
lasers broadly tunable in the 2000-2100 nm spectral range.