High-energy, frequency-doubled thulium-doped fiber chirped-pulse amplification system at 950 nm

Compact, high-energy ultrafast sources at less exploited fiber gain wavelengths can enable various applications. Here, a high pulse-energy (138 nJ) femtosecond (390 fs) laser source with a center wavelength around 950 nm is demonstrated by frequency-doubling of ultrafast pulses from a thulium-doped fiber chirped-pulse amplification system. The thulium-doped fiber system generates an average output power of 6.5 W around a wavelength of 1.9 µm whose pulses (703 nJ) can be compressed to a pulse duration of 490 fs. This ultrafast 950 nm source offers an attractive system for applications, including two-photon microscopy, and marks the highest-energy fiber system at this wavelength to date.