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Noise suppression of a differential detector under high levels of illumination, relevant to terahertz electro-optic sampling

In electro-optic detection of terahertz transients, the photodiodes of a differential detector are often illuminated with optical powers on the order of several milliwatts. We present measurements that show that the response of the photodiodes at these power levels is distorted, giving rise to frequ...

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Bibliographic Details
Published in:Review of scientific instruments 2005-07, Vol.76 (7), p.073104-073104-5
Main Authors: van der Valk, N. C. J., Schouten, R. N., Planken, P. C. M.
Format: Article
Language:English
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Summary:In electro-optic detection of terahertz transients, the photodiodes of a differential detector are often illuminated with optical powers on the order of several milliwatts. We present measurements that show that the response of the photodiodes at these power levels is distorted, giving rise to frequency-dependent amplitude and phase changes in the electrical signal from these diodes. We find that these distortions significantly reduce the ability of the detector to suppress laser amplitude noise. Surprisingly, this occurs at power levels at which the dc output of each photodiode shows no sign of saturation. Based on our measurements, we provide experimenters with recommendations to improve the amplitude noise suppression of a differential detector under high levels of illumination.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.1947667