SOLID-STATE TECHNIQUES FOR MODULATION AND DEMODULATION OF OPTICAL WAVES.
Abstract
MODULATION: A fairly detailed investigation of certain cubic electro-optic materials is presently underway. Studies on cuprous chloride and hexamethylene-tetramine have been initiated thus faj. These materials have Pockel's coefficients with magnitudes comparable to KDP and further may be operated with the applied electric field oriented transverse to the light path. DEMODULATION: A large signal gain effect at avalanche breakdown voltage was observed in both planar and mesa silicon photodiodes. A signal-to-noise ratio improvement of as high as 13 db was measured at microwave frequencies in L-band region. This effect is believed to be similar to the multiplier phototube gain effect in that a signal amplification in the avalanche region results by collision induced electron multiplication. Near the avalanche breakdown voltage increases in signal strength were observed to be as high as 28 db. The general signal enhancement effect at avalanche breakdown was observed for modulation frequencies ranging all the way from the audio to the microwave range. The highest microwave modulated frequency seen with silicon photodiodes has been with the use of the avalanche effect. This was at a frequency at somewhat in excess of 2 kilomegacycles. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1964
- Accession Number
- AD0600419
Entities
Organizations
- Texas Instruments