Experimental method of transfer function linewidth determination for laser amplifiers using FM-to-AM conversion

Area of Science:

• Optics and Photonics
• Laser Physics
• Spectroscopy

Background:

• Characterizing laser amplifier performance is crucial for many optical applications.
• Accurate determination of transfer function linewidth is essential for predicting laser behavior.
• Existing methods may not fully capture the dynamic characteristics of laser amplifiers.

Purpose of the Study:

• To propose and validate an experimental method for determining the transfer function linewidth of a laser amplifier.
• To investigate the relationship between amplifier transfer function and output spectrum.
• To assess the suitability of Q-switched laser output spectra as representative of amplifier characteristics.

Main Methods:

• Development of an experimental technique based on transfer function scanning.
• Utilizing frequency modulation to amplitude modulation (FM-to-AM) temporal modulation measurements.
• Performing measurements as a function of wavelength to map the transfer function.

Main Results:

• Successfully implemented an experimental method for transfer function linewidth determination.
• Demonstrated that the output spectrum of a laser amplifier in Q-switch mode is not representative of its transfer function.
• Provided wavelength-dependent measurements of the amplifier's temporal modulation characteristics.

Conclusions:

• The proposed FM-to-AM scan method provides a more accurate measure of laser amplifier transfer function linewidth.
• Q-switched output spectra are insufficient for representing the true transfer function of the amplifier.
• This work offers a new tool for precise laser amplifier characterization.