Stabilization of an active harmonically mode-locked fiber laser using two-photon absorption

Area of Science:

• Optics and Photonics
• Laser Physics
• Semiconductor Devices

Background:

• Harmonically mode-locked fiber ring lasers are crucial for generating high-repetition-rate optical pulses.
• Amplitude fluctuations and pulse dropouts degrade laser performance and limit applications.
• Existing methods for stabilizing such lasers often face limitations in efficiency or complexity.

Purpose of the Study:

• To investigate the efficacy of two-photon absorption in semiconductor mirror structures for stabilizing fiber ring lasers.
• To demonstrate the reduction of amplitude fluctuations and elimination of pulse dropouts.
• To assess the impact on picosecond pulse generation at high repetition rates.

Main Methods:

• Fabrication and integration of a semiconductor mirror structure exhibiting two-photon absorption into a fiber ring laser cavity.
• Characterization of laser output stability, including amplitude noise measurements.
• Analysis of pulse train integrity to detect and quantify pulse dropouts.

Main Results:

• Significant reduction in amplitude fluctuations was observed with the semiconductor mirror.
• Complete elimination of pulse dropouts was achieved in the harmonically mode-locked fiber ring laser.
• The laser reliably produced picosecond pulses at a 2 GHz repetition rate with enhanced stability.

Conclusions:

• Two-photon absorption in semiconductor mirrors offers an effective method for stabilizing fiber ring lasers.
• This approach significantly improves pulse quality by eliminating dropouts, crucial for high-speed optical systems.
• The demonstrated technology holds promise for advanced laser applications requiring high stability and repetition rates.