Probing and Control of Guided Exciton-Polaritons in a 2D Semiconductor-Integrated Slab Waveguide

Area of Science:

• Condensed Matter Physics
• Materials Science
• Optoelectronics

Background:

• Guided 2D exciton-polaritons are crucial for on-chip optical devices due to their long propagation distances and nonlinear interactions.
• These quasiparticles, formed by coupling excitons and waveguide modes, are typically difficult to access directly from free space.

Purpose of the Study:

• To demonstrate a novel method for probing and manipulating guided polaritons in a 2D semiconductor system.
• To investigate the transition from weak to strong coupling and its effect on polariton linewidth.

Main Methods:

• Utilized evanescent coupling via a high-index solid immersion lens to interact with guided polaritons in a Ta2O5 slab with a WS2 monolayer.
• Precisely tuned the nanoscale lens-sample gap to extract system parameters.
• Observed the motional narrowing effect as coupling strength increased.

Main Results:

• Successfully probed and manipulated guided 2D exciton-polaritons using the developed evanescent coupling technique.
• Demonstrated the transition from weak to strong coupling, observing the lifting of inhomogeneous broadening.
• Showcased the ability to extract intrinsic system parameters by tuning the lens-sample gap.

Conclusions:

• The developed method provides a powerful tool for characterizing and controlling guided polaritons.
• This work facilitates the advancement of integrated optics utilizing room-temperature 2D exciton-polaritons.
• The findings pave the way for novel on-chip optical devices based on 2D semiconductors.