Abstract:

We report the demonstration of surface-plasmon microcylinder quantum cascade lasers with circular and deformed resonators. An improved self-alignment fabrication technique was developed that allows the use of wet etching, necessary to achieve smooth and clean surfaces, in combination with the deposition of the surface-plasmon-carrying metal layer up to the very edge of the resonator, where the optical mode is mostly located. The diameter of the microcylinders ranges from 75 to 180 /spl mu/m while their deformation coefficient /spl epsiv/ ranges from /spl epsiv/=0 to /spl epsiv/=0.32. Circular microcylinder lasers show a reduction of /spl sim/50% of the threshold current density with respect to devices with standard ridge-waveguide resonators. On the other hand, highly deformed microcylinder lasers exhibit a complex mode structure, suggesting the onset of chaotic behavior.