The periodic scattering of the surface plasmon modes employed in the waveguide of terahertz quantum cascade lasers is shown to be an efficient method to control the properties of the laser emission. The scatterers are realized as thin slits in the metal and top contact layer carrying the surface plasmon. This technique provides larger coupling strengths than previously reported and can be used in various device implementations. Here the method is applied to realize a distributed feedback resonator without back-facet reflection, to achieve vertical emission of the radiation with second-order gratings, and to increase the facet reflectivity by fabricating passive distributed Bragg reflectors.

Articles you may be interested inSubband electronic temperatures and electron-lattice energy relaxation in terahertz quantum cascade lasers with different conduction band offsets

We report on ZnO nanoparticles‐polystyrene (PS) nanocomposites (NC) engineered to modify PS matrix permeability and refractive index (n), and to fabricate 1D all‐polymer photonic crystals (PC) for sensing applications. The new NC can be easily processed from solutions to prepare high quality thin films by spin coating. ZnO nanoparticles (n = 1.98) have been synthetized by solvothermal route and grafted with a silane to reduce phase segregation in the PS matrix (n = 1.58). Such procedure led to an increase of the matrix refractive index of about 1%. By casting alternated layers of the NC and cellulose acetate (CA, n = 1.46), we fabricated free‐standing and flexible distributed Bragg reflectors (DBRs) of excellent optical quality. Preliminary results on the use of such DBRs as solvent vapor sensors are reported. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

THz-sensing is an emerging technology that would be advantageous for a variety of applications in industry, biology, biochemistry and security, if small and convenient to use sources and detectors would be readily available. However, most of them are bulky, complicate to operate, and need cryogenic cooling. Here we present a new detection scheme that is versatile enough to detect electro-magnetic radiation within the whole spectrum, can be easily applied to the THz-range, and operates at room temperature. The mechanism is based on the resonant excitation of a quartz tuning fork.