An investigation is undertaken into methods of fast modulation and detection of submillimetre radiation. Detection at room temperature was achieved with travelling wave antennae coupled to a crystal rectifier. Metal-oxide-metal and metal-oxide-semiconductor rectifying junctions were studied. Generation of submillimetre radiation was performed by means of a hydrogen cyanide laser, operating primarily at a wavelength of 337 mum. The investigation was motivated by a need for an increase in output power from the laser which requires a fast switch operative at submillimetre wavelengths. Evaluation of a Q-switching technique, utilizing the near coincidences between absorption features in various vapours and the 337 mum emission line of the HCN laser was made. Further investigations were carried out on the transient properties of the plasma that forms the active medium of a pulsed excited HCN laser. Shift of the resonance condition by means of an ancillary discharge is undertaken as a Q-switching technique. Magneto-optical modulation as an alternative switching technique was also studied. To this end, the temperature-dependence of the magneto optical constants of seven different rare-earth iron garnets were studied at a wavelength of 337 mum. The properties investigated include the Faraday rotation, absorption coefficient and the room temperature refractive index. The theory of the magneto-optical effects at microwave and optical frequencies is reviewed and extended into the sub-millimetre region. Effects of magnetic anisotropy are discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:479578 |
| Date | January 1979 |
| Creators | Booton, Martin Wynford |
| Publisher | Royal Holloway, University of London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://repository.royalholloway.ac.uk/items/05fb3d3f-748f-453f-bb75-867b402dd99e/1/ |
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