All-fiber construction of a femtosecond erbium-doped laser and study of frequency doubling

Femtosecond pulses with wavelengths of 700 nm to 800 nm have a wide range of applications in the fields of biological two-photon imaging, terahertz imaging, coherent Raman spectroscopic microimaging, and material micromachining. In recent years, the primary technical method for obtaining 780 nm pulse output has been frequency doubling by erbium-doped lasers. Based on this, an all-polarization-maintaining erbium-doped fiber laser was constructed in this experiment. The effects of different kinds of dispersion-compensated PM2000D and G.652C on the frequency-doubling process were investigated by using the fiber chirped pulse amplification (FCPA) technique as well as a periodically polarized lithium niobate (PPLN) crystal. In the experiments, a pulse output with a wavelength of 1564 nm and a pulse width of 87 fs was obtained with a power of 2.23 W using PM2000D, and a pulse output with a wavelength of 782 nm and a pulse width of 83 fs with a power of 601.8 mW was realized by frequency doubling with a periodically poled lithium niobate (PPLN) crystal. Utilizing the G.652C standard, a pulse output with a wavelength of 1568 nm and a pulse width of 95 fs was achieved with a power of 2.23 W. Additionally, a pulse output with a wavelength of 788 nm and a pulse width of 85 fs was attained with a power of 540.6 mW. The experimental results offer a point of reference for the frequency doubling study of a femtosecond erbium-doped fiber laser.