DIRECT OBSERVATION OF MICROWAVE-FREQUENCY BEATS DUE TO PHOTOMIXING OF RUBY-OPTICAL-MASER MODES
Abstract
Observations were made of microwave signals produced by photomixing of near-neighbor axialmode components in the output spectrum of a ruby optical maser (laser). The observations were made by focusing the laser out ut onto the oxide cathode of an operating 2500-4000 Mc travelingwave tube. Mixing (heterodyning) between the simultaneous, discrete optical frequencies in the laser output occurs in the TWT cathode, producing microwave amplitude modulation of the beam current. This amplitude modulation is amplified in the helix section, producing easily observable microwave signals in the TWT output. Within the TWT bandwidth, discrete signals were observed at 1800 plus or minus 20, 2410 plus or minus 3, 3000 plus or minus 20, and 3600 plus or minus 20 Mc, representing the 'photo-beats' between third- through sixth-nearest neighbors in the laser-mode spectrum. This method of observation is a powerful tool for study of optical masers, and also has significant implications for communications employing microwavemodulated light. It verifies a number of suggestions for constructing microwave phototubes outlined by the authors at a recent conference. (Phys. Rev. 99:1691, 1955) (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 25, 1961
- Accession Number
- AD0264455
Entities
People
- A.e. Siegman
- B.j. Mcmurtry
Organizations
- Stanford University