A 105-GHz bandwidth optical-to-electrical conversion stimulus probe head employing a unitraveling-carrier photodiode

An optical-to-electrical conversion stimulus probe head that employs a unitraveling-carrier photodiode (UTC-PD) and a quartz coplanar-waveguide (CPW) transmission line has been developed. The fabricated probe head offers the minimum full-width at half-maximum of 2.85 ps corresponding to a -3-dB bandwidth of 105 GHz for optimum incident power and bias conditions. A monotonically gradual attenuation to -20 dB over the frequencies of up to 350 GHz was obtained with the small group delay dispersion of <10.1 ps. The responsivity was 0.13 A/W. The saturation output voltage at 1-dB compression was 800 mV/sub p-p/. This probe head can be utilized for both pulse-pattern excitation at up to 100 Gb/s and impulse excitation for 350-GHz-bandwidth network measurements.