Hybrid and monolithic integrated optic/millimeter-wave converters for 60 GHz radio-over-fiber systems
Hybrid as well as monolithic integrated /spl lambda/=1.55 /spl mu/m optic/millimeter-wave converters were developed and investigated experimentally based on detailed microwave simulations. Both converters working near 60 GHz showed responsitivities of about 1 A/W in good agreement with the simulations.
Maximum directivity beam-former at 60 GHz with optical feeder
We present an optically controlled 60 GHz array antenna which may be used as a smart antenna in an envisaged broadband mobile communication system. The desired field patterns of the antenna were synthesized using the maximum directivity beam-forming algorithm which enables an optimum radio link to a selected mobile terminal to be created while the signals of other terminals are suppressed by the nulls of the antenna's field distribution. The 60 GHz signals were generated by optically heterodyning the signals of two laser diodes. The field distribution of the antenna was formed by a silica based photonic beam-forming network. The experimentally obtained data confirmed the calculated field patterns.
Waveguide-integrated InP-InGaAs-InAlGaAs MSM photodetector with very-high vertical-coupling efficiency
We report on a novel implementation of long-wavelength vertically-coupled waveguide-integrated metal-semiconductor-metal (MSM) InGaAs photodetectors which results in a significantly improved guide-to-absorber coupling efficiency. By employing an In/sub 0.53/Al/sub 0.31/Ga/sub 0.16/As buried strip waveguide embedded in InP, a coupling length of only 20 /spl mu/m is sufficient to obtain an internal quantum efficiency greater than 95%. Moreover, the photoresponse is found to be virtually independent of the polarization state of light coupled into the input waveguide. The device parameters agree with the results of eigenmode calculations.