Development of ferromagnetic spinels for optical isolation at 10. 6. mu. m. Progress report, May 1, 1977--July 31, 1977
An analysis of factors which influence the optical transparency of hot-pressed CdCr/sub 2/S/sub 4/ at 10.6 ..mu..m was made. It was found that multiphonon absorption, an intrinsic process, is the factor which limits the ultimate achievable absorption coefficient, ..cap alpha.., at 10.6 ..mu..m. Several extrinsic processes have also been found to affect the transmission of hot-pressed CdCr/sub 2/S/sub 4/. In sufficient concentration, oxygen appearing as SO/sub 4//sup 2 -/ or similar sulfate complexes contribute to ..cap alpha.. through an absorption band centered at 9.3 ..mu..m. Cr/sub 2/O/sub 3/, appearing as a second phase with a different index of refraction, causes scattering in concentrations as low as .01 mole percent. Despite the identification of these processes, possible uncertainties in the value of reflectivity, and surface losses, prevent the establishment of a definite lower limit on the absorption coefficient. It was firmly established that ..cap alpha.. at 10.6 ..mu..m is decreased significantly upon cooling to 77/sup 0/K. Thus, an ..cap alpha.. of .5 cm/sup -1/, which would give a transmission of 85 percent in an optical isolator, still appears to be possible. CdCr/sub 2/Se/sub 4/ is suggested as an alternative material since the potential of a lower intrinsic ..cap alpha.. is a direct consequence of its lower phonon frequencies. It is proposed that CdCr/sub 2/Se/sub 4/ be emphasized in future work rather than CoCr/sub 2/S/sub 4/.
- Research Organization:
- Rochester Univ., N.Y. (USA)
- OSTI ID:
- 5242869
- Report Number(s):
- COO-4056-4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ABSORPTION
ABSORPTION SPECTROSCOPY
CADMIUM COMPOUNDS
CADMIUM SULFIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM SULFIDES
ELECTROMAGNETIC RADIATION
INFRARED RADIATION
INORGANIC PHOSPHORS
OPACITY
OPTICAL PROPERTIES
PHOSPHORS
PHYSICAL PROPERTIES
RADIATIONS
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360603* -- Materials-- Properties
ABSORPTION
ABSORPTION SPECTROSCOPY
CADMIUM COMPOUNDS
CADMIUM SULFIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM SULFIDES
ELECTROMAGNETIC RADIATION
INFRARED RADIATION
INORGANIC PHOSPHORS
OPACITY
OPTICAL PROPERTIES
PHOSPHORS
PHYSICAL PROPERTIES
RADIATIONS
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS