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SBS reduction in nanosecond fiber amplifiers by frequency chirping
Optics Express
|July 14, 2016
Summary
We reduced stimulated Brillouin scattering (SBS) in a nanosecond Yb-fiber amplifier by applying a frequency chirp to seed pulses. This method increased the SBS threshold nearly ninefold, enabling higher power amplification.
Area of Science:
- Fiber laser technology
- Nonlinear optics
- High-power laser systems
Background:
- Stimulated Brillouin scattering (SBS) is a major limitation in high-power fiber amplifiers.
- Managing SBS is crucial for achieving higher energy and power outputs from nanosecond Yb-fiber amplifiers.
Purpose of the Study:
- To demonstrate a novel technique for SBS reduction in nanosecond Yb-fiber amplifiers.
- To investigate the impact of frequency chirp on SBS threshold and gain.
- To show the feasibility of spectral recovery after amplification.
Main Methods:
- Imposing a 1.19 GHz/ns frequency chirp on seed pulses using a phase modulator.
- Measuring SBS threshold and transient SBS gain for various chirp rates.
- Comparing experimental data with theoretical calculations.
- Applying an opposite chirp to recover the initial spectrum.
Main Results:
- A nearly 9-fold increase in the SBS threshold was achieved for 8.4 ns pulses.
- Detailed SBS threshold data and transient SBS gain measurements were obtained.
- Experimental results were found to be in good agreement with theoretical predictions.
Conclusions:
- Frequency chirping is an effective method for suppressing SBS in nanosecond Yb-fiber amplifiers.
- The demonstrated technique allows for significant enhancement of the SBS threshold.
- The spectral characteristics of the amplified pulses can be restored using a compensating chirp.
