Stretched-pulse operation of a thulium-doped fiber laser.

We report on stretched-pulse operation of a thulium-doped fiber laser. The laser generated pulses at a center wavelength of 1974 nm with an energy of 4 nJ that could externally be compressed to a duration of 173 fs.

Wavelength resolved intracavity measurement of the cross sections of a Tm-doped fiber.

The wavelength dependent measurement of the relaxation oscillation frequency in a laser oscillator allows the study of the three- and four-level nature of the active material. Accordingly we present a tunable thulium doped fiber laser that covers the transition from three- to four-level operation at 2025 nm, characterized by the vanishing occupation of the terminal laser level. The laser is tunable from 1864 nm to 2075 nm with a linewidth below 0.3 nm. A maximum output power of 3.8 W at 1930 nm was achieved with a slope efficiency of 33.6% and an absorbed pump power of 17.5 W. Absorption and emission cross sections were derived over the tuning range by an intracavity measurement method.

Ultrafast thulium-doped fiber-oscillator with pulse energy of 4.3 nJ.

A femtosecond fiber laser based on thulium-doped double-clad silica fiber with an internal dispersion compensation is presented that generates pulses at a center wavelength of 1976 nm with an energy of 4.3 nJ and a duration of 1.2 ps. The dechirped pulse duration is 294 fs. The pulse energy is more than 2 orders of magnitude above the pulse energy demonstrated previously. Mode locking is achieved using additive pulse mode locking, and dispersion compensation is facilitated by a grating stretcher arrangement.

Single-Frequency ytterbium-doped fiber laser with 26 nm tuning range.

A core-pumped ytterbium-doped fiber laser is presented, tunable over 26 nm from 1017 nm to 1043 nm. A diffraction grating pair in Littman-Littrow configuration in the unidirectional ring-cavity provides the wavelength adjustment. The laser resonator with a free spectral range of 260 MHz supported stable single frequency operation with a maximum linear polarized output power of 31 mW.

Stable sub-85 fs passively mode-locked Erbiumfiber oscillator with tunable repetition rate.

We present a sub-85 fs self-starting stretched-pulse passively mode-locked Erbium-fiber oscillator in a sigma setup with tunable repetition rate. The sigma cavity included a movable mirror enabling a tunable pulse repetition rate variation of +/- 1 % from 55.3 MHz to 56.4 MHz with continuous, uninterrupted mode-locked operation and an output power around 14 mW. Based on the wide tuning range of the repetition rate the presented fiber oscillator is a suitable candidate for applications in femtosecond spectroscopy or precision metrology around 1.56 microm.