Noise characterization of femtosecond fiber Raman soliton lasers

The broadband amplitude noise and phase noise (timing jitter) measured in femtosecond fiber Raman soliton lasers is discussed. For a single-pass compressor using 300 m of either standard single-mode fiber or polarization preserving fiber, white amplitude noise >or=50 dB above shot noise at 2 mA photocurrent was measured, for frequencies higher than approximately 100 kHz. This is approximately=30 dB larger than the amplitude noise observed from fiber grating pulse compressors. The timing jitter increases with pump power, and at 1.6 W pump power, 5.2 ps r.m.s. timing jitter was measured, given approximately=2 ps jitter from the Nd:YAG pump. Longer fibers in the single-pass compressor do not affect the amplitude noise, but increase the timing jitter even further. A synchronously pumped ring cavity reduced the timing jitter substantially, but did not significantly improve the amplitude noise.>