Spin-dependent directional emission from a quantum dot ensemble embedded in an asymmetric waveguide.

Area of Science:

• Photonics
• Quantum Optics
• Materials Science

Background:

• Quantum dots (QDs) offer unique light-emitting properties.
• Spin-orbit interaction of light is crucial for controlling light direction.
• Photonic waveguides are essential components in optical circuits.

Purpose of the Study:

• To investigate spin-dependent directional emission from quantum dots in a photonic wire.
• To explore the use of a stair-like waveguide cross-section for enhanced light control.
• To demonstrate the integration of quantum dots with microdisk resonators for unidirectional light coupling.

Main Methods:

• Numerical simulations were performed to verify emission directionality.
• A photonic wire waveguide with a two-step stair-like cross-section was designed.
• Quantum dots were embedded in the upper step of the waveguide.
• A microdisk resonator with a stair-like edge was analyzed for mode coupling.

Main Results:

• More than 70% of the radiation from the quantum dot ensemble was directed to a specific waveguide direction.
• The circular polarization of emission from spin-polarized QDs controlled radiation direction.
• The microdisk resonator selectively coupled QD emission into a unidirectional whispering gallery mode.

Conclusions:

• Spin-orbit interaction enables spin-controlled directional light emission in photonic structures.
• The designed photonic wire and microdisk resonator show potential for efficient spin-based light manipulation.
• This work provides a foundation for developing novel spin-dependent optoelectronic devices.