Resonant cavities based on Parity-Time-symmetric diffractive gratings.

Area of Science:

• Photonics and Optics
• Quantum Physics
• Materials Science

Background:

• Traditional Distributed Feedback (DFB) and Distributed Bragg Reflector (DBR) structures rely on refractive index modulation.
• Achieving unidirectional functionality in optical gratings is a significant challenge.
• Parity-Time (PT) symmetry offers a new paradigm for designing optical devices.

Purpose of the Study:

• To explore a new class of DFB and DBR structures utilizing Parity-Time (PT) symmetry.
• To design and analyze novel unidirectional Bragg gratings with both phase and amplitude modulation.
• To investigate the unique lasing properties of concatenated unidirectional gratings.

Main Methods:

• Theoretical analysis using a transfer matrix approach.
• Design of unidirectional Bragg gratings with periodic phase and amplitude variations.
• Concatenation of two unidirectional Bragg gratings to form new DFB/DBR structures.

Main Results:

• Demonstration of unidirectional Bragg gratings that are transparent from one side and reflective from the other.
• Proposed novel DFB and DBR structures exhibiting unique transmission and reflection characteristics.
• Identification of a key characteristic: inherent single lasing mode support.

Conclusions:

• The proposed PT-symmetric DFB and DBR structures offer unprecedented unidirectional optical control.
• These structures pave the way for advanced photonic devices with tailored functionalities.
• The inherent single lasing mode property is crucial for applications requiring mode selectivity.