PT symmetry breaking and nonlinear optical isolation in coupled microcavities

Area of Science:

• Nonlinear optics
• Quantum physics
• Photonics

Background:

• Nonlinear optical isolators are crucial for controlling light propagation.
• Coupled microcavities offer a promising platform for novel photonic devices.
• Understanding the interplay of gain, loss, and nonlinearity is key for device performance.

Purpose of the Study:

• To theoretically investigate the nonlinear dynamics of coupled microcavity optical isolators.
• To explore the relationship between asymptotic stability and PT-symmetry breaking.
• To identify mechanisms for actively controlling optical isolation.

Main Methods:

• Theoretical analysis of nonlinear coupled-mode equations.
• Investigation of systems with gain and loss.
• Examination of parameter regimes including detuning and input intensity.

Main Results:

• A direct correspondence was found between the nonlinear stability boundary and the PT-breaking transition.
• The onset of optical isolation was rigorously derived and linked to the PT-broken phase.
• Unequal external couplings led to an abrupt jump in isolation ratio at the transition point.

Conclusions:

• The study reveals a fundamental connection between PT-symmetry and nonlinear optical isolation.
• Actively controlled nonlinear optical isolators can be realized by tuning inter-resonator separation.
• This work offers a pathway for developing novel photonic devices with switchable isolation properties.