Environmentally stable passively modelocked fiber laser pulse source

A fiber laser having a linear optical resonator, comprising:

• a fiber gain medium having optical transitions operable to absorb optical carriers at a pump wavelength of a specified wavelength range and to emit optical carriers at a laser wavelength that is different from said pump wavelength;
• first and second reflective elements disposed relative to said fiber gain medium to form a linear optical resonator that encloses said fiber gain medium and supports a plurality of longitudinal modes;
• a saturable absorber disposed in said optical resonator and configured to exhibit an intensity-dependent absorption, said saturable absorber operable to effect a mode-locking mechanism that locks said longitudinal modes in phase to produce optical pulses at said laser wavelength;
• a pump light source, operable to produce a pump beam at said pump wavelength which optically excites said fiber gain medium;
• an optical coupler, disposed relative to said fiber gain medium to couple said pump beam into said fiber gain medium;
• and
• a tuning element located in said optical resonator and configured to change either the optical length of said optical resonator or said laser wavelength.