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FBG can improve the spectral efficiency of mmwave fiber-radio systems employing wavelength interleaving and optical single-sideband modulation. Our results demonstrate the effectiveness of the FBG in dropping the required carrier wavelength and sideband. In addition excellent isolation between the added and dropped channels was demonstrated when the FBG was employed in asystem incorporatingbathaddanddropconfigurations. We are now investigating the aptimilation of the grating in order to improve the rolloff of the transmission notches and minimize transmission amplitude ripples. References1. G. Smith, D. Novak and C. Lim,"A millimeter-wave full duplex fiber radio star-tree architecture incorporating WDM and SCM," IEEE Photon. Tech. Lett. vol. 10, pp. 1 6 5 6 1652 (1998). 2. H. Schmuck, "Comparison of optical miL limeter-wave system concepts with regard to chromaticdispersion:'Electron.

The optimisation of a 1300nm buried heterostructure (BH) InGaAsP/InP DFB laser for uncooled directly modulated 10Gbit/s operation is described. The development process as well as the key process parameters are discussed and results are presented on an optimised structure. Bandwidths in excess of 10GHz were measured at 90C chip base temperature. Clean open eye diagrams were recorded over the full temperature range, resulting in error free transmission over 40km. To our knowledge the results represent the current state of the art for uncooled BH DFB lasers operating at 1300nm.

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Quartz crystal filters used in modern carrier systems present new problems in manufacturing technique. In the assembly and testing of the filters and in the production of component crystals, coils and condensers, special factory facilities are required for accurate measurement of frequency and control of atmospheric conditions. The manufacture of quartz crystal plates in particular combines several fields of applied science, including crystallography, precision grinding, vacuum technique and high frequency electrical measurement. Inductance coils and fixed and variable condensers for use in crystal filters must consistently meet advanced requirements, especially in regard to stability. The assembly of these components into filters resembles the manufacture of radio receivers, differing mainly because of smaller quantity requirements. Testing equipment must permit rapid shop adjustment and test of the completed filters with laboratory precision.