Single-mode generation in the random fiber laser with an embedded microcavity.

Area of Science:

• Photonics
• Laser Physics
• Optical Engineering

Background:

• Fiber lasers are crucial for various applications, but achieving narrow spectral linewidths and single-line generation can be challenging.
• External microresonators offer potential for spectral control in laser systems.

Purpose of the Study:

• To demonstrate narrow-band generation with a stable single spectral line using a fiber laser with an embedded external microresonator.
• To investigate the spectral characteristics and stability of this laser system.

Main Methods:

• Utilized a random fiber laser architecture.
• Integrated an external microresonator into the laser cavity.
• Operated the laser near its lasing threshold.
• Analyzed the generated spectrum using a high-resolution optical spectrum analyzer.

Main Results:

• Achieved narrow-band generation with a stable single spectral line at approximately 1.55 µm.
• Observed a spectral width of less than 10 MHz.
• Demonstrated wavelength stability for thousands of seconds.
• Noted sensitivity to acoustic noise and vibrations.
• Observed multimode generation with increased power, governed by the microresonator's free spectral range.

Conclusions:

• The proposed fiber laser with an embedded microresonator effectively produces narrow-band, single-line generation.
• The system's stability is high but susceptible to environmental factors.
• The microresonator dictates mode spacing in multimode operation, offering a method for spectral shaping.