Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 23: Symposium Quantenkaskadenlaser
HL 23.1: Vortrag
Dienstag, 25. März 2003, 15:15–15:45, POT/81
Terahertz Quantum Cascade Lasers — •Rüdeger Köhler1, Alessandro Tredicucci1, Fabio Beltram1, Harvey Beere2, Edmund Linfield2, Giles Davies2, and David Ritchie2 — 1NEST-INFM and Scuole Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy — 2Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
Lasing action at THz frequencies has recently been demonstrated in quantum cascade (QC) structures. In these devices, a novel type of waveguide, loosely based on the surface plasmon concept, provides a high overlap (∼ 50%) of the optical mode with a series of chirped superlattices that host the interminiband laser transition.
Advanced processing and fabrication has led to significant performance improvements, and lasers emitting 4.4 THz radiation can now be operated up to 70 K with low temperature threshold current densities of less than 200 A/cm2. Continuous-wave emission has been accomplished with output powers of several mW per facet up to about 50 K. The latter result allowed us to perform an in-depth analysis of the gain-transport properties of the structure, which can yield important information for optimising the design.
Research now focuses also on reaching lower operation frequencies towards 1 THz. Preliminary results at 3.5 THz are very encouraging, showing record low threshold current densities (about 100 A/cm2) and very low optical losses.