An electrically pumped phonon-polariton laser

Abstract

We report a device that provides coherent emission of phonon polaritons, a mixed state between photons and optical phonons in an ionic crystal. An electrically pumped GaInAs/AlInAs quantum cascade structure provides intersubband gain into the polariton mode at λ = 26.3 μm, allowing self-oscillations close to the longitudinal optical phonon energy of AlAs. Because of the large computed phonon fraction of the polariton of 65%, the emission appears directly on a Raman spectrum measurement, exhibiting a Stokes and anti-Stokes component with the expected shift of 48 meV.

Observation of Intersubband Absorption in ZnO Coupled Quantum Wells

“…While being extensively studied, an underexplored yet extremely interesting property of ZnO is its large optical phonon energy (approximately 72 meV) compared with those of GaAs and (In, Ga)As commonly used for the intersubband optoelectronic devices. Even though the p doping of ZnO remains a huge challenge, it does not hinder ZnO from being a candidate for unipolar devices based on intersubband transitions (ISBTs), such as quantum cascade detectors (QCDs) [11,12], phononpolariton lasers [13], and quantum cascade lasers (QCLs) [14], especially in the THz range at high temperature [15]. In fact, for ISBTs below the optical phonon energy of ZnO [e.g., in the terahertz (THz) range], the population inversion of THz QCLs is significantly enhanced at high temperature due to the suppressed optical phonon emission rate, thus significantly enhancing the high temperature operation of THz QCLs [16,17].…”

Microcavity phonon polaritons from the weak to the ultrastrong phonon–photon coupling regime

“…The strong and ultrastrong coupling between light and phonons offers intriguing possibilities for various fundamental studies and applications, including polaritonic control of THz waves in polar crystals 21 , which in combination with microresonators 22,23 , can be used for the development of phonon polariton lasers 24,25 . At surfaces or on thin layers of polar crystals, strong phonon-photon coupling can also lead to surface phonon polaritons and hyperbolic volume phonon polaritons 26,27 that allow for nanoscale concentration of infrared and terahertz fields, which could lead to novel communication and sensing technologies 28,29 , particularly in form of nanoresonators 26,30,31 or by coupling the polaritons with plasmonic antennas and metasurfaces [32][33][34][35][36] .…”

Investigation of Phonon Polaritons in an hBN GaN Heterostructure

“…And while hBN has attracted some research due to its similarities to other popular research materials; graphene, black phosphorous, transition metal dichalcogenides; it has yet to be applied in a superlattice for light source and detection. While there are industrial applications for such a THz active region, future projects could lead to emission of electromagnetic radiation and phonons, a fascinating new category, of which there is only one [4]. For a more complex solid, we look at a two-atom primitive cell.…”

“…Coupling of the particles decreases the density of states close to the anti-crossing point, reducing the threshold. [4].…”

“…Polaritons are an IR alternative to plasmons; these quasiparticles are formed from light coupling to an elementary material excitation, such as phonons, plasmons, magnons, or excitons. These quasiparticles are lighter than electrons and of bosonic nature, making them ideal candidates for realizing Bose-Einstein condensation at higher temperatures [1], [2], extending THz laser source options [3], and emitting optical phonons [4].…”