Optical steering of a large ring laser.

Area of Science:

• Laser Physics
• Optical Engineering

Background:

• Increasing resonator length in lasers reduces linewidth but can lead to multi-mode operation in large gas lasers.
• Multi-mode operation or mode hopping causes instability, unsuitable for precision applications like ring laser gyroscopes.

Purpose of the Study:

• To propose and demonstrate a method for achieving stable, single-mode operation in ring lasers.
• To enable precise control over laser mode selection for metrological and sensing applications.

Main Methods:

• Optical steering of a ring laser to a specific mode index.
• Utilizing injection locking with an external laser source.
• Investigating the effect of intra-cavity backscattering on mode behavior.

Main Results:

• Stable operation on a selected mode index was successfully established through external injection locking.
• The injected mode reliably followed the steering signal from the external laser.
• Intra-cavity backscattering was shown to influence the counter-propagating mode, causing it to also follow the external steering.

Conclusions:

• The proposed injection locking method effectively achieves stable, single-mode operation in ring lasers.
• This technique offers precise control over laser mode selection, enhancing suitability for sensitive applications.
• The phenomenon of intra-cavity backscattering can extend mode control to counter-propagating beams.