Open AccessGain dynamics of clad-pumped Yb-fiber amplifier and intensity noise control
Author(s) -
Jian Zhao,
Germain Guiraud,
Florian Floissat,
Benoît Gouhier,
Sergio Rota-Rodrigo,
Nicholas Traynor,
Giorgio Santarelli
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.000357
Subject(s) - relative intensity noise , optics , amplifier , materials science , fiber laser , optical amplifier , physics , optical fiber , laser , optoelectronics , semiconductor laser theory , cmos
Gain dynamics study provides an attractive method to understand the intensity noise behavior in fiber amplifiers. Here, the gain dynamics of a medium power (5 W) clad-pumped Yb-fiber amplifier is experimentally evaluated by measuring the frequency domain transfer functions for the input seed and pump lasers from 10 Hz to 1 MHz. We study gain dynamic behavior of the fiber amplifier in the presence of significant residual pump power (compared to the seed power), showing that the seed transfer function is strongly saturated at low Fourier frequencies while the pump power modulation transfer function is nearly unaffected. The characterization of relative intensity noise (RIN) of the fiber amplifier is well explained by the gain dynamics analysis. Finally, a 600 kHz bandwidth feedback loop using an acoustic-optical modulator (AOM) controlling the seed intensity is successfully demonstrated to suppress the broadband laser intensity noise. A maximum noise reduction of about 30 dB is achieved leading to a RIN of -152 dBc/Hz (~1 kHz-10 MHz) at 2.5 W output power.