Simple and economic optical high-speed photo-detector ac response determination method in the 850 nm spectral range

摘要

Limitations to a novel opto-electronic method of determining the ac response of fast photo-detectors (frequency range > GHz) in the 850 nm spectral region, based on a broadband, spectrally resolved separation of optical relative intensity and shot noise, are investigated. In common with a number of related techniques developed over the years, the method relies on the whiteness of quantum shot noise, which has the fundamental property of presenting a constant power level across all frequencies, to reveal the ac detector response over a potential large spectral range. The present work is, however, believed to be the first to exploit in this context a classic method of separating shot noise from other noise spectra for detector response determination, even in situations where non-white noise light sources are used. The method demands a minimum of extra equipment and could be appropriate for field measurements in optical communication and optical sensor systems. On the other hand, the new method has larger measurement uncertainties (several dB) than other methods of determining photo-detector ac response.