The expressions for the reset noise in capacitive-transimpedance-amplifier (CTIA) readout circuits are theoretically derived and confirmed experimentally. The contributions to the reset noise from the thermal current and amplifier noise are considered. The thermal reset noise is found to depend only on the feedback capacitance among the circuit parameters.

The characteristics of 155 Mbps optical propagation through atmosphere at the wavelengths of 0.78 and 1.55 m over a 72 m range were measured. Two propagation characteristics were compared to examine the wavelength dependence on the rain rate and the aperture size of a receiver. An enhanced intensity exceeding the signal level measured in the absence of rain was observed at both wavelengths during 7.2 mm/h rain. The resultant bit error rate is shown to be dominated mainly by the rain-induced scintillation rather than the attenuation.

We measured the optical propagation characteristics during rainfall over a 72-m propagation distance at the wavelengths of 0.78, 1.55, and 2.0 µm. In addition to the common attenuations, we observed sudden drops (dips) in the received optical power, which affect communication errors. The temporal interval of most dips is approximately 1 ms.