Electrooptical Modulator. Volume 1.

The objective of this program was to evaluate and compare various available electrooptical modulator materials appropriate for 0.53 micrometers and 1.06 micrometers modulation. The evaluation data provide a more rational basis for selection of an optimum modulator material for the design of a modulator for near term use with a high-bit-rate, mode-locked NdYAG laser. The effects imposed upon the subnanosecond optical bit stream were experimentally analyzed by the operation of the electrooptical modulator material. The effects of particular importance included variations to the beam divergence, spatial reorientations, temporal distortions of the subnanosecond pulse shape, and resulting far field effects. Materials compared included Ammonium Dihydrogen Phosphate ADP, Potassium Dihydrogen Phosphate KDP, Potassium Dideuterium Phosphate KD, Lithium Niobate LiNbO3, Lithium Tantalate LiTaO3, Barium Sodium Niobate Ba2NaNb5O15, and Strontium Barium Niobate Srx3a1-xNb2U6. Optimum materials were first tested in bulk configurations, and the most promising were then more fully tested in the physical configuration of a modulator. As a result of this investigation, it was concluded that lithium tantalate is the best modulator material choice for use with a mode-locked NdYAG laser at both the fundamental 1.06 micrometers wavelength and the frequency-doubled 0.53 micrometers wavelength in high-data-rate communication applications.