Ultrashort pulse fiber amplifier using rare-earth doped gain fibers

A 1.51 to 1.65 micron wavelength ultrashort pulse fiber amplifier with pulse width from 200 ps to 200 fs, comprising an Erbium doped multicomponent glass gain fiber for laser amplification from 1.51 to 1.65 micron wavelength, comprising:

• a core;
• and
• a cladding;
• wherein:
• said core comprises at least 2 weight percent glass network modifier selected from BaO, CaO, MgO, ZnO, PbO, K2O, Na2O, Li2O, Y2O3, or combinations thereof;
• and
• erbium oxide at a level from about 0.5 to about 20 weight percent;
• wherein:
• a step index difference between the core and the cladding is configured to guide a mode of the core;
• a numerical aperture of the gain fiber is between 0.01 and 0.04;
• a core diameter is from about 30 microns to about 90 microns;
• a length of the gain fiber is shorter than 60 cm;
• said fiber amplifier comprising no pulse-stretching devices and no pulse-compressing devices.