An electrically pumped phonon-polariton laser.

Area of Science:

• Condensed Matter Physics
• Quantum Optics
• Materials Science

Background:

• Phonon polaritons are hybrid light-phonon quasiparticles crucial for infrared optics.
• Achieving coherent emission from these states is challenging but offers unique applications.
• Quantum cascade structures provide a versatile platform for optoelectronic devices.

Purpose of the Study:

• To demonstrate coherent emission of phonon polaritons using an electrically pumped device.
• To investigate the properties of these hybrid quasiparticles near optical phonon frequencies.
• To confirm the polaritonic nature of the emission through spectroscopic analysis.

Main Methods:

• Utilized a GaInAs/AlInAs quantum cascade structure for intersubband gain.
• Engineered the device to target the polariton mode at a wavelength of 26.3 μm.
• Employed Raman spectroscopy to analyze the emitted light and its spectral components.

Main Results:

• Achieved self-oscillation of phonon polaritons close to the longitudinal optical phonon energy of AlAs.
• Determined a significant phonon fraction (65%) within the polariton state.
• Observed distinct Stokes and anti-Stokes components in Raman spectra, confirming the polariton's energy shift (48 meV).

Conclusions:

• The developed device successfully generates coherent phonon polariton emission.
• The results validate the strong coupling between photons and optical phonons in the system.
• This work paves the way for novel optoelectronic devices operating in the mid-infrared spectrum.