Fig. 1: Electrically pumped quantum cascade laser (QCL) based on a photonic Majorana zero mode (MZM).
From: Photonic Majorana quantum cascade laser with polarization-winding emission
a An air-hole structure is patterned into the top Au/QCL layers. The top and bottom Au layers work as electric conductors for pulsed pump current injection, as well as tight mode confinement in the vertical direction due to the small Ohmic losses at terahertz frequencies. The region outside the cavity is insulated by a SiO2 layer so that it is unpumped. b SEM image of a fabricated sample, which has lattice constant \(a=30\) μm, winding number \(w=+ 1\), vortex core radius \(\xi=2a\), and an overall device radius of six periods. The side view of the SEM shows that the QCL is undercut relative to the top Au contact.
