Development of tunable THz wire lasers

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The proposed research seeks to develop broadly tunable terahertz quantum-cascade lasers (THz QCLs) based on a novel tuning mechanism that was recently (in 2009) demonstrated by the proposing principal investigator's group. This tuning mechanism is qualitatively different from all the other methods implemented in tunable lasers, in which either the dielectric constant or the longitudinal component of the wavevector is changed to tune the frequency of an already fabricated laser device. The novel tuning mechanism takes advantage of the relatively long wavelength at THz frequencies and is achieved in the extreme limit of wire lasers, whose cross section is much smaller than the wavelength. Intellectual merit: The concept of wire lasers is new, and it was developed only recently by analyzing unexpected beam patterns of these lasers. There are many unique properties associated with this unusual device. One of them is that the laser frequency can be tuned by changing the transverse mode profile. Broader impacts: The principal investigator has been invited to give invited/plenary/keynote talks at many prestigious conferences. The work from the PI's group has also been reported in media for broad communities such as Technology Review, Laser Focus, and NPR Market Place. Through collaborations, the THz lasers developed in the PI's group have helped to enhance infrastructures at other institutions in THz-related activities by adding a crucial enabling component. The principal investigator will incorporate elements in the research project into a graduate course in solid-state physics and a undergraduate core course Signals and Systems.