Two-photon injection of polaritons in semiconductor microstructures.

Area of Science:

• Quantum optics
• Condensed matter physics
• Semiconductor science

Background:

• Excitons are crucial for light-matter interactions in semiconductors.
• Quantum wells and microcavities confine excitons, enabling unique optical properties.
• Two-photon pumping offers a non-linear excitation method for studying excitonic states.

Purpose of the Study:

• To demonstrate two-photon pumping of dark excitons for exciton-polariton generation.
• To investigate photon lasing from dark excitons in semiconductor microcavities.
• To explore the conversion of dark excitons into exciton-polaritons via stimulated emission.

Main Methods:

• Experimental setup involving quantum wells within semiconductor microcavities.
• Two-photon excitation of "dark" excitons.
• Observation of threshold behavior indicative of lasing in a semiconductor micropillar.

Main Results:

• Successful demonstration of two-photon pumping of dark excitons leading to exciton-polariton injection.
• Observation of clear threshold behavior in a semiconductor micropillar, characteristic of vertical cavity surface-emitting laser (VCSEL) transitions.
• Evidence of stimulated emission of terahertz photons facilitating dark exciton to exciton-polariton conversion.

Conclusions:

• Two-photon pumping of dark excitons is a viable method for generating exciton-polaritons.
• The observed lasing behavior confirms the efficient conversion of dark excitons into exciton-polaritons.
• This work opens new avenues for terahertz photon generation and quantum information processing using semiconductor systems.