Near-field imaging of the evanescent electric field on the surface of a quantum cascade laser

This paper demonstrates quantum cascade (QC) lasers employing waveguides based on air-confinement can be implemented on structures where the active region is located immediately at the device top surface, while previous devices featuring this architecture made use of thick top, doped semiconductor claddings to provide uniform current injection. The second part of the paper presents the imaging of the evanescent electric field at the device top surface performed with a mid-IR apertureless scanning near-field optical microscope (SNOM).