Abstract

We report on a high peak power pulsed fiber laser emitting in the L band limited by stimulated Brillouin scattering (SBS). On-going developments target at building fiber lasers for CO2 sensing from space such as ASCENDS emitting at 1572nm [1]. Unfortunately the relevant CO2 lines compatible with Erbium amplification are located in the L amplification band, where the cross sections are small. Consequently, those fiber sources have low non-linear threshold and low efficiency. The European Space Agency is funding a project dedicated to the design of a high power pulsed fiber laser for CO2 DIAL monitoring with emission lines located closed to 1579nm. The system requires 150 ns pulse duration at 4kHz pulse repetition frequency (PRF). The high precision on the CO2 concentration measurement requires narrow linewidth and the laser is primarily limited by Stimulated Brillouin Scattering (SBS). SBS threshold can be improved by: reducing fiber length, reducing effective Brillouin gain or increasing effective area. Due to the small cross-sections of Erbium in L band, large doping concentration or large fiber length are required. Large mode area phosphate Erbium-Ytterbium codoped fibers have been used to generate 84μJ for 1μs pulses with 1% efficiency [1] which corresponds to ~84W peak power.

© 2013 IEEE