Tuning a terahertz wire laser

The authors demonstrate a novel tuning mechanism based on the unique feature of an unusual device termed "wire laser", which is defined as a laser whose dimension in the transverse direction
w
is much smaller than ¿. As such, a large fraction of the mode propagates outside the solid core. Placing a movable object close to the wire laser allows direct manipulation of the evanescent laser field, and consequently the lasing frequency. Based on this mechanism, continuous frequency tuning has been unambiguously demonstrated with single-mode operation free from mode hopping.