Accession Number : ADA294009

Title :   Efficient Pockel's Modulators in Optical Fibres.

Descriptive Note : Final rept. 15 Sep 92-14 Mar 95,

Corporate Author : SOUTHAMPTON UNIV (UNITED KINGDOM)

Personal Author(s) : Kazansky, P. G. ; Russell, P. S.

PDF Url : ADA294009

Report Date : 31 MAR 1995

Pagination or Media Count : 47

Abstract : The main aim of this project was to study the feasibility of using thermal poling of glasses as a means of realizing efficient electro-optic modulators in optical fibres. We found that substantial spreading out of the second-order nonlinearity beyond the boundaries of the positive electrode occurs, and also showed that implantation of electrons erases the second-order nonlinearity in thermally poled glass. This erasure technique holds much promise as a versatile new means of realising complex patterns for advanced electro-optic modulators. We proposed a mechanism for the thermal poling process based on a frozen-in space charge field; this model explains both our own and other recorded experimental results. Ge doping of silica glass observed to enhance both thermal poling (in combination with OH doping) and electron beam poling effects. Effective values of second-order nonlinearity as high as 0.2 pm/V were obtained in Ge-doped silica fibres. This value is approx. 200 times higher than ever previously reported in these optical fibres. The use of thermal poling in vacuum to improve in reproducibility and quality of the induced second-order susceptibility was proposed and experimentally demonstrated. Strong electro-acousto-optic transduction in thermally poled fibre was observed. Phase shift at resonance as high as 1 radian was obtained at applied fields of 0.3 V/microns. A value of electrooptic coefficient of 0.05 pm/V was experimentally measured. This value is about 25 times higher then previously reported in silica fibres and may be increased by optimisation of poling conditions. (MM)

Descriptors :   *FIBER OPTICS, *ELECTROOPTICS, *LIGHT MODULATORS, *SILICA GLASS, OPTICAL INTERFEROMETERS, ELECTRODES, RESONANCE, DOPING, GERMANIUM, ACOUSTOOPTICS, PHASE SHIFT, POCKELS CELLS, OPTICAL GLASS.

Subject Categories : Electrooptical and Optoelectronic Devices
      Ceramics, Refractories and Glass
      Fiber Optics and Integrated Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE