Strongly confined, low-threshold laser modes in organic semiconductor microgoblets.

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• High-quality factor (high-Q) microcavities are crucial for low-threshold lasers.
• Polymeric goblet-type microcavities offer unique optical confinement properties.
• Organic semiconductors are promising gain materials for microcavity lasers.

Purpose of the Study:

• To investigate lasing performance in high-Q polymeric goblet-type microcavities.
• To analyze the effect of organic semiconductor gain layer thickness on optical mode confinement and lasing characteristics.
• To establish a numerical method for predicting optimal gain layer thickness.

Main Methods:

• Finite element simulations were used to analyze optical modes in the microcavities.
• A numerical method was developed to determine the cutoff thickness for whispering gallery mode confinement.
• Fabrication and characterization of microcavity devices with varying gain layer thicknesses.

Main Results:

• Whispering gallery modes become strongly confined in the gain layer above a critical thickness.
• Fabricated devices demonstrated reduced lasing thresholds with increasing gain layer thickness.
• A red-shift in laser emission was observed concurrently with the reduced lasing threshold.

Conclusions:

• Gain layer thickness is a critical parameter for optimizing lasing in polymeric microcavity lasers.
• Enhanced optical mode filling factor in thicker gain layers leads to lower lasing thresholds.
• The findings provide insights for designing efficient organic semiconductor microcavity lasers.