title: Low-threshold quantum-cascade lasers at 3.5 THz (lambda = 85 microm).
abstract: Chirped-superlattice quantum-cascade lasers are reported that emit at lambda approximately 85 microm (3.6 THz), which is to the authors' knowledge the longest wavelength demonstrated so far with this technology. Collected peak output powers of 1.5 mW per facet were measured at liquid-helium temperature, and a maximum operating temperature of 45 K was reached. Record low-threshold-current densities of 95 and 115 A cm(-2) were observed in pulsed and continuous-wave operation, respectively. For the latter, output powers of a few hundred microwatts are estimated at low temperatures.
authors.affiliation: National Enterprise for nanoScience and nanoTechnology-Istituto Nazionale per la Fisica della Materia, Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy. r.koehler@sns.it
authors.forename: Rüdeger
authors.initials: R
authors.lastname: Köhler
authors.forename: Alessandro
authors.initials: A
authors.lastname: Tredicucci
authors.forename: Fabio
authors.initials: F
authors.lastname: Beltram
authors.forename: Harvey E
authors.initials: HE
authors.lastname: Beere
authors.forename: Edmund H
authors.initials: EH
authors.lastname: Linfield
authors.forename: A Giles
authors.initials: AG
authors.lastname: Davies
authors.forename: David A
authors.initials: DA
authors.lastname: Ritchie