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Interference filters and their impact on FM-to-AM conversion: a method for investigation and characterization
Applied Optics
|November 11, 2020
Summary
High-power nanosecond laser pulses can be distorted by frequency modulation to amplitude modulation (FM-to-AM) conversion. This study introduces a spectral measurement method to detect and quantify interference filters causing these distortions, estimating their impact on laser performance.
Area of Science:
- Optics and Photonics
- Laser Physics
- Nonlinear Optics
Background:
- High-power nanosecond laser pulses often undergo spectral broadening using temporal phase modulations.
- Stimulated Brillouin scattering and focal spot smoothing are key challenges addressed by spectral broadening.
- Frequency modulation to amplitude modulation (FM-to-AM) conversion can negatively impact laser performance by inducing power modulations.
Purpose of the Study:
- To investigate interference filters as contributors to FM-to-AM conversion in high-power laser systems.
- To develop an indirect method for detecting and quantifying FM-to-AM conversion caused by interference filters.
- To estimate the magnitude of power modulations resulting from interference filter-induced FM-to-AM conversion.
Main Methods:
- Utilizing spectral measurements as an indirect diagnostic tool.
- Analyzing spectral data to identify and quantify parameters of interference filters.
- Developing a methodology to correlate spectral characteristics with FM-to-AM conversion effects.
Main Results:
- Demonstrated an indirect spectral measurement technique to identify FM-to-AM conversion contributors.
- Successfully quantified the defining parameters of interference filters.
- Established a method to estimate the range of power modulations induced by these filters.
Conclusions:
- Interference filters are significant contributors to detrimental FM-to-AM conversion in high-power laser systems.
- Spectral measurements provide a viable indirect approach for diagnosing and quantifying FM-to-AM conversion.
- The developed method allows for the estimation of power modulations, aiding in laser performance optimization.
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