Statistical parity-time-symmetric lasing in an optical fibre network

Area of Science:

• Optics and Photonics
• Quantum Physics
• Materials Science

Background:

• Parity-time (PT)-symmetry in optics balances real and imaginary refractive indices.
• This symmetry enables phenomena like unidirectional invisibility and loss-induced lasing.
• Previous PT-symmetry experiments were limited to small, on-chip devices due to fragility concerns.

Purpose of the Study:

• To investigate the robustness of PT-symmetry in macroscopic optical systems.
• To explore PT-symmetry's lasing dynamics in long, fiber-based coupled cavities.
• To observe symmetry breaking in a macroscopic PT-symmetric system.

Main Methods:

• Utilizing kilometer-long optical fiber-based coupled cavities.
• Implementing balanced gain and loss within the cavities.
• Analyzing lasing dynamics, threshold, and power under statistical fluctuations.

Main Results:

• PT-symmetry features demonstrated robustness against statistical fluctuations in a macroscopic cavity.
• Lasing threshold and power behavior aligned with PT-stable system predictions.
• Statistical symmetry breaking was observed as cavity loss was varied.

Conclusions:

• PT-symmetry is not inherently fragile and can be realized in large-scale optical systems.
• Macroscopic PT-symmetric systems exhibit predictable lasing dynamics despite environmental fluctuations.
• This work opens possibilities for robust PT-symmetric devices at larger scales.