Ultralow-threshold six-photon-excited upconversion lasing in a plasmonic microcavity

Area of Science:

• Photonics
• Nonlinear Optics
• Quantum Electrodynamics

Background:

• Nonlinear multiphoton absorption (MPA) upconversion lasers are vital for fluorescence imaging and biological photonics.
• Enhancing nonlinear light-matter interactions is key to improving upconversion laser performance.

Purpose of the Study:

• To realize ultralow-threshold six-photon-excited upconversion lasing.
• To investigate the role of cavity quantum electrodynamics in plasmonic microcavities for enhanced nonlinear optics.

Main Methods:

• Utilizing a plasmonic microcavity to enhance cavity quantum electrodynamics effects.
• Employing a hybrid whisper-gallery mode (WGM) structure with a microwire (MW).
• Measuring the Purcell factor (Fp) and comparing upconversion lasing thresholds.

Main Results:

• Achieved ultralow-threshold six-photon upconversion lasing.
• Enhanced the Purcell factor (Fp) five-fold in the plasmonic WGM compared to a bare MW.
• Reduced the lasing threshold by one order of magnitude due to plasmonic enhancement.
• Observed distinct temperature and polarization characteristics for upconversion lasing.

Conclusions:

• Plasmonic microcavities significantly enhance nonlinear light-matter interactions for upconversion lasing.
• Cavity quantum electrodynamics effects in plasmonic WGMs enable ultralow-threshold lasing.
• This approach offers a pathway for extreme nonlinear optics with improved processability and high Purcell factors.