Design of a multiple self-mixing interferometer for a fiber ring laser

Area of Science:

• Optics and Photonics
• Fiber Optic Sensing
• Interferometry

Background:

• Fiber ring lasers (FRLs) are utilized in various sensing applications.
• Self-mixing interferometry offers a compact sensing approach.
• Existing FRL interferometers face limitations in measurement accuracy.

Purpose of the Study:

• To design a novel multiple self-mixing interferometer for a fiber ring laser.
• To improve the accuracy of fiber optic measurement systems, especially Doppler velocimeters.
• To develop a robust method for extracting Doppler frequency from complex self-mixing signals.

Main Methods:

• A circular feedback cavity was introduced into an injection-seeded erbium-doped FRL.
• A system model based on Dragic's proposed FRL was established.
• A double-peak frequency identification algorithm was developed to analyze the self-mixing signal spectrum.

Main Results:

• The designed interferometer produced multiplied fringes of varying depths due to collimator lens reflection.
• Two distinct Doppler frequencies were observed in the self-mixing signal spectrum.
• The proposed algorithm successfully extracted the Doppler frequency from the unique signal.

Conclusions:

• The novel multiple self-mixing interferometer design enhances fiber ring laser sensing capabilities.
• The developed double-peak frequency identification algorithm improves Doppler frequency extraction accuracy.
• This technique shows significant potential for advancing fiber optic Doppler velocimetry and other measurement systems.