Investigations of optically pumped submillimeter wave laser modes

Principles and Performance of an Electron Spin Echo Spectrometer Using Far Infrared Lasers as Excitation Sources

“…Since the best reported values for these kind of diodes are 2000 K, a factor of 30 can still be gained in sensitivity (24).…”

“…The field distribution in a metallic waveguide is given by the TE mn and the TM mn modes, which are the solutions of the Maxwell equations for special boundary conditions. The attenuation ␣( 0 ) for the TE mn mode in a circular waveguide with diameter 2a is given by (24,29,30) …”

“…Here, we can profit from the enormous progress which has been made in the field of radio astronomy, where very sensitive heterodyne detectors have been developed for spectroscopic applications (24). These detectors, using a Schottky diode as mixer, offer both a high sensitivity and a very good time resolution.…”

Transformation of the multimode terahertz quantum cascade laser beam into a Gaussian, using a hollow dielectric waveguide

“…The impetus for using hollow core dielectric waveguides to shape the TQCL beam comes from their wide application in optically pumped submillimeter-wave molecular lasers where, in contrast to metal waveguides, they provide excellent transverse mode control [21]. Single transverse mode, Gaussian profile output is readily obtained with large volume dielectric waveguides, where ratios of core tube diameter, d, to wavelength, , exceed 100͞1.…”

“…where N ϭ ͱ 1 ͞ 0 is the complex index of refraction of the tube material [21]. The attenuation constant for a given mode varies as 2 ͞a 3 , so a waveguide with a larger radius has lower loss.…”