Laser altimetry and deep space communications are two typical applications requiring very low noise optical receivers in order to achieve detection of weak and short optical pulse. Avalanche photodiode is the detector of choice for its high quantum efficiency, compact size, reduced electronics complexity and its ability to operate in a radiation-hard environment. Optimal operating condition in terms of APD gain and temperature is the key to maximize the signal to noise ratio.This paper describes the model and the measured performance of a hybrid optical receiver using a TE cooled Silicon Avalanche Photodiode. Receiver performance in terms of responsivity and NEP will be presented as a function of temperature, signal power and APD Gain. A brief discussion of radiation impact on noise is also presented. A NEP of only 5fW/sqrt(Hz) has been obtained with a bandwidth of 200MHz in linear mode at a wavelength of 1060nm.
Silicon photomultipliers with high photon detection efficiency in the 350 to 800 nm range and low dark count rate are currently being developed in a variety of geometry, microcell size and area in order to address the needs of the analytical, life science, medical imaging community as well as for various scientific and technological applications. This SiPM development platform is based on previous knowledge of low dark count avalanche photodiode operated in Geiger-mode found in the Excelitas single photon counting module. Low dark counts and low temperature sensitivity are especially important when tiling up SiPMs to form larger area detectors such as block detectors typically used in positron emission tomography. The latest developments include; 1. Optical trenches to suppress crosstalk which allowed to increase the operating voltage range from 5 to 10 V above breakdown, 2. Tailored parasitic capacitance to obtain single photon timing resolution close to 200 ps FWHM and 3. Improved PDE at shorter wavelengths by optimizing the entrance window. A corrected energy resolution of 12.0 % was typically obtained at 511 keV which, alongside the good timing resolution, makes this SiPM a perfect candidate for time-of-flight PET and other application requiring a timing resolution better than 200 ps.
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