Electro-optical modulators in particle detectors

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Abstract
Results of an investigation to minimize the local electronics in particle detectors using electro‐optical intensity modulators are reported. The electrical charge signals from a particle detector are first applied to a low noise electronic charge‐sensitive preamplifier and the resulting signal charges are converted into optical signals using an integrated Ti:LiNbO3 Mach–Zehnder interferometric optical modulator. By driving the optical modulator with a low noise diode‐pumped Nd:YAG laser at a wavelength of 1.3 μm and detecting the output signals using a fast pulse shaping technique, the charge output of a particle detector can be measured at high rates with high accuracy up to 3 decades of dynamic range. The performance characteristics of such a detector signal transfer scheme, using first a single channel optical modulator and then a 16‐channel integrated optical modulator array, is reported. Using the charge output from a multiwire proportional chamber, this electrical charge to optical signal transfer scheme is compared to the conventional particle detection technique. Effects of radiation dose on the optical modulator are also presented. Finally, the implication of using such an optical technique is discussed.