Defect mode emission of a dye doped cholesteric polymer network

Area of Science:

• Materials Science
• Photonics
• Polymer Chemistry

Background:

• Cholesteric polymer networks exhibit photonic band gaps, influencing light propagation.
• Photonic defect modes can be engineered to control light emission and lasing properties.
• Dye doping introduces active gain medium within photonic structures.

Purpose of the Study:

• To investigate the creation and optical properties of a photonic defect mode in a dye-doped cholesteric polymer network.
• To analyze the impact of a helix phase jump on fluorescence and laser emission.
• To determine the lasing threshold and polarization characteristics of the defect mode.

Main Methods:

• Fabrication of a stacked cholesteric polymer film with a controlled helix phase jump at the interface.
• Characterization of optical properties using fluorescence spectroscopy.
• Investigation of laser emission under pulsed excitation.

Main Results:

• Observation of an additional resonant mode within the photonic stop band of the cholesteric polymer.
• Achieved laser emission from the defect mode with a remarkably low lasing threshold.
• The defect mode emission displayed circular polarization opposite to the cholesteric helix.

Conclusions:

• A photonic defect mode can be effectively introduced in dye-doped cholesteric polymer networks by controlling helix orientation.
• This defect mode enables efficient light amplification and low-threshold laser action.
• The unique polarization properties of the defect mode emission offer potential for novel optical applications.