Electron intersubband transitions to 0.8 eV (1.55 μm) in InGaAs/AlAs single quantum wells

We report a polarization-resolved infrared absorption study of the quantum-well-width dependence of the electron intersubband transitions in strained InGaAs/AlAs single quantum wells (SQWs) 3, 4, and 5 monolayers (ML) in width. An intersubband transition energy as high as 0.8 eV (i.e., a wavelength as short as 1.55 μm) is observed with transverse magnetic field polarization for a 3-ML-thick InGaAs SQW. This is the highest quantum-well intersubband transition energy ever reported in any materials system.