The Asymmetric Active Coupler: Stable Nonlinear Supermodes and Directed Transport.

Area of Science:

• Photonics and Optical Engineering
• Nonlinear Optics
• Waveguide Physics

Background:

• Active optical couplers are crucial for controlling light propagation.
• Understanding nonlinear effects in coupled waveguides is essential for advanced photonic devices.
• Asymmetric systems introduce unique dynamics not present in symmetric counterparts.

Purpose of the Study:

• To investigate the existence and properties of nonlinear supermodes in asymmetric active couplers (AACs).
• To explore the conditions under which these modes arise, beyond parity-time symmetry.
• To demonstrate the potential for directed power transport in such systems.

Main Methods:

• Theoretical analysis of coupled dissimilar waveguides with incorporated gain and loss.
• Investigation of nonlinear phenomena under generic conditions.
• Mathematical formulation to identify finite-power, constant-intensity nonlinear supermodes.

Main Results:

• Existence of finite-power, constant-intensity nonlinear supermodes (NS) in AACs.
• These modes arise from a balance of gain, loss, nonlinearity, coupling, and waveguide dissimilarity.
• Demonstration of non-reciprocal dynamics enabling directed power transport.

Conclusions:

• Asymmetric active couplers can support novel nonlinear supermodes.
• The observed non-reciprocal dynamics offer a pathway for unidirectional light control.
• Findings pave the way for new functionalities in optical signal processing and transport.