Using Guide Wavelengths to Assess Far-Infrared Laser Emissions

DeShano, Brad; Olivier, Kerry; Cain, B.; Zink, L. R.; Jackson, Michael

doi:10.1007/s10762-014-0104-x

Cited by 2 publications

(1 citation statement)

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“…Multiple modes of a far-infrared laser wavelength (i.e., TEM 00 , TEM 01 , etc.) can be generated within the laser cavity and thus it is important to identify the appropriate adjacent cavity modes being used to measure the wavelength 13,29,41 . To assist in eliminating higher order modes, irises are included within each laser cavity.…”

Section: Discussionmentioning

confidence: 99%

Characterizing Far-infrared Laser Emissions and the Measurement of Their Frequencies

Jackson

Zink

2015

JoVE

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The generation and subsequent measurement of far-infrared radiation has found numerous applications in high-resolution spectroscopy, radio astronomy, and Terahertz imaging. For about 45 years, the generation of coherent, far-infrared radiation has been accomplished using the optically pumped molecular laser. Once far-infrared laser radiation is detected, the frequencies of these laser emissions are measured using a three-laser heterodyne technique. With this technique, the unknown frequency from the optically pumped molecular laser is mixed with the difference frequency between two stabilized, infrared reference frequencies. These reference frequencies are generated by independent carbon dioxide lasers, each stabilized using the fluorescence signal from an external, low pressure reference cell. The resulting beat between the known and unknown laser frequencies is monitored by a metal-insulator-metal point contact diode detector whose output is observed on a spectrum analyzer. The beat frequency between these laser emissions is subsequently measured and combined with the known reference frequencies to extrapolate the unknown far-infrared laser frequency. The resulting one-sigma fractional uncertainty for laser frequencies measured with this technique is ± 5 parts in 10 7. Accurately determining the frequency of far-infrared laser emissions is critical as they are often used as a reference for other measurements, as in the high-resolution spectroscopic investigations of free radicals using laser magnetic resonance. As part of this investigation, difluoromethane, CH 2 F 2 , was used as the far-infrared laser medium. In all, eight far-infrared laser frequencies were measured for the first time with frequencies ranging from 0.359 to 1.273 THz. Three of these laser emissions were discovered during this investigation and are reported with their optimal operating pressure, polarization with respect to the CO 2 pump laser, and strength. Video LinkThe video component of this article can be found at

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Section: Discussionmentioning

confidence: 99%