Intersubband polaritons at λ ∼ 2 <italic>μ</italic>m in the InAs/AlSb system.

We demonstrate intersubband polaritons at very short wavelengths, down to λ ∼ 2 <italic>μ</italic>m, using a mature semiconductor material system InAs/AlSb and a metal-insulator-metal resonator architecture. The demonstration is given for intersubband transitions centered at 350 meV (λ = 3.54 <italic>μ</italic>m) and 525 meV (λ = 2.36 <italic>μ</italic>m). The polaritonic dispersions are measured at room-temperature and minimum splittings (Rabi splitting) of ≈50 meV are observed. We also quantitatively show that non-parabolicity effects limit the Rabi energy that can be obtained and must be crucially taken into account to correctly model these devices. Intersubband polaritons operating in the short-wave infrared region could enable the use of extremely effective pump laser sources in the quest for an intersubband polariton laser. [ABSTRACT FROM AUTHOR]