Generation and amplification of ultrashort pulses in erbium-doped optical fibers

Erbium-doped optical fiber is used in order to create and amplify picosecond to sub-picosecond pulses at the technologically significant wavelength of 1.55 {dollar}mu{dollar}m in the third communications window.; The waveguide properties of optical fiber are exploited in order to utilize near-instantaneous nonlinear effects such as cross- and self-phase modulation for the creation of frequency and amplitude modulation necessary for pulse generation. A method for actively mode locking an erbium/ytterbium fiber with a pulsed Nd:YAG pump laser using cross-phase modulation is demonstrated. The output of the fiber laser is a train of 2-4 ps pulses synchronized to the pump pulse train. In a separate set of experiments, nonlinear polarization evolution is used in order to passively mode lock an erbium fiber laser via amplitude modulation. The effect of group velocity delay is studied and the results are used in order to create pulses of as short as 100 fs. The cavity design is further optimized by employing polarization maintaining fiber to help improve the environmental stability of the laser.; Finally, we demonstrate the use of chirped pulse amplification to amplify the pulses generated by an erbium-doped fiber source in an erbium-doped fiber amplifier in order to avoid nonlinear effects. We obtain clean, 440 fs pulses with a gain of 18 dB in a single stage of amplification at a repetition rate of 33 MHz.