THZ QUANTUM CASCADE LASER WITH MICRO-DISC RESONATOR AND VERTICAL EMISSION BY A SECOND-ORDER GRATING

A circular semiconductor laser, comprising a laser resonator (1) having a planar active region (3), a first (2) and a second (6) wave-guide layer that define the active region (3). The resonator (1) has a shape that is defined by a circular perimeter, along which the first layer (2) radiation guide has a plurality of radial cuts (4) forming a lattice. The number of said cuts 4 is a prime number, or an odd number that is a multiple of a prime number, said prime number greater than or equal to five. This way, it is avoided that resonance modes evolve outside of the zone with the cuts, or in any case with a component that is different from zero of the wave vector in a radial direction, and a pure whispering gallery operating mode is obtained, with maximum of the emitted radiation that evolves in a vertical direction, i.e. orthogonal to the plane of the laser resonator, and without that the laser emitted radiation evolves in a radial direction.