HETERODYNE GENERATION OF LONG WAVELENGTH INFRARED ENERGY.
Abstract
A study of heterodyne generation of very-far-infrared radiation (10-400/cm) from two visible or near-infrared laser beams has been performed. Two possible nonlinear mechanisms that can provide mixing were studied both theoretically and experimentally, with emphasis on the latter. In one, the electric field of the incident radiation modulates the susceptibility or index-of-refraction: in the other, the absorption coefficient. The latter was calculated to be the more promising mechanism, with possible generation of 10 to the -8th power W of radiation at 20/cm; the former would, at best, produce 10 to the -12th power W of radiation. The two laser beams were derived from a single GaAs injection laser which is sufficiently tuneable so that the difference frequency could be tuned to the required 50-100/cm. The mixing material was semi-insulating GaAs in a large dc electric field for the nonlinear absorption, semi-insulating GaAs or GaP, LiNbO3, for nonlinear susceptibility. The far-infrared radiation was collected and detected with cooled bolometers optimized to a sensitivity of a few times 10 to the -13th power W. No clearcut difference-frequency radiation was detected by either technique. In some cases radiation up to 5 x 10 to the -12th power W was clearly present, but it did not have all the required characteristics, although it could not be ascribed to any other source either. In any case, it was concluded that it is not feasible at this time to obtain a practical amount of far-infrared radiation by heterodyne techniques. Rather, a considerable improvement in the output of tuneable lasers must be awaited. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1966
- Accession Number
- AD0480107
Entities
People
- Dietrich Meyerhofer
Organizations
- Sarnoff Corporation