Intersubband Polariton-Polariton Scattering in a Dispersive Microcavity

Area of Science:

• Quantum Optics
• Condensed Matter Physics
• Mid-Infrared Spectroscopy

Background:

• Intersubband polaritons in semiconductor quantum wells are crucial for novel optical phenomena.
• Dispersive cavities and GaAs/AlGaAs quantum wells provide a platform for studying polariton dynamics.
• Understanding ultrafast scattering is key to controlling quantum states.

Purpose of the Study:

• To investigate the ultrafast scattering dynamics of intersubband polaritons.
• To explore polariton behavior within the band structure using specific excitation conditions.
• To identify the microscopic mechanisms governing polariton interactions.

Main Methods:

• Utilizing a noncollinear pump-probe geometry with phase-stable mid-infrared pulses.
• Directly studying dynamics within the band structure of GaAs/AlGaAs quantum wells.
• Employing a quantum mechanical model to analyze scattering processes.

Main Results:

• Selective excitation of lower polaritons at ~25 THz and finite in-plane momentum (k‖).
• Observed narrowband maximum in probe reflectivity at k‖=0.
• Identified stimulated coherent polariton-polariton scattering as the underlying process.

Conclusions:

• The study elucidates the mechanism of stimulated coherent polariton-polariton scattering.
• These findings represent a significant step towards quantum control in polaritonic systems.
• The results are vital for developing custom-tailored polaritonic systems for bosonic lasing in the mid and far infrared.