We study the use of polymeric components to achieve efficient outcoupling of radiation from double-metal-waveguide THz quantum cascade lasers. We employ cyclicolefincopolymer to realize optical fibers with diameters between 60mm and 1000mm, and characterize their absorption coefficient at 2.9THz. We show that assembling a fiber on the facet of a singleplasmon quantum cascade laser improves its far field radiation pattern, making it narrower. We also provide a design of a broadband directional coupler that can be used to couple radiation from a doublemetal quantum cascade laser waveguide into the tapered end of a metal coated optical fiber.
A portable, stand-alone, real-time THz imaging system for high resolution is presented. The total weight of the apparatus
is less than 15 kg and its physical dimension is of approximately (65 cm)3. A quantum cascade laser emitting at 3.4 THz
based on a third-order distributed feedback cavity is used as radiation source for transmission and reflection imaging
modes. We report real-time THz imaging with a bolometric camera operating at 15 Hz producing movies with a
resolution of 120 x 160 pixels. With the help of a Stirling motor cryocooler the laser operates in continuous-wave at 40 K
with more than 1 mW output power and less than 300 mW of power consumption. We were able to image small objects
employing refractive elements that we manufactured in high density polyethylene achieving a resolution of twice the
We present a development of a broad gain heterogeneous quantum cascade laser for terahertz frequencies. By
placing appropriate different active-regions based on a four-quantum-well design into a double-metal
waveguide we obtained laser emitting gapless over a bandwidth of 1 THz, between 3.2 to 2.2 THz. This means
that this single-device source covers an emission range of nearly 40 % around the center frequency. In pulsed
mode operation, our devices show threshold current density as low as 285 A/cm2 and they operate up to 125 K.
We also report on continuous wave measurements.