White Papers

Technical Insights for Optical System Design

Browse GPD Optoelectronics’ library of technical white papers covering photodiode fundamentals, detector design, and real-world applications in optical sensing. Each paper offers practical insight for engineers working across aerospace, defense, telecommunications, and scientific instrumentation.

Link to: Fundamentals of Light Detection
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Fundamentals of Light Detection

This practical guide for engineers covers semiconductor physics, PN junction behavior, and major detector types, including PIN, APD, and Schottky designs, with material comparisons across silicon, germanium, and InGaAs. It also explains specialized geometries such as quadrant cells, tetralateral position-sensing detectors, and sandwich detectors for two-color detection.

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Free Space Optical Communications in Terrestrial & Satellite Systems with an InGaAs Quadrant Photodiode

This white paper traces free space optical communication from ancient line-of-sight signaling to modern terrestrial, satellite systems. It covers pointing, acquisition, tracking mechanics, quadrant photodiode sensors used for beam alignment, key performance metrics: sensitivity, surface uniformity, crosstalk, temporal response. It closes on emerging CubeSat constellations enabling precise bidirectional laser communication across Low Earth Orbit, Medium Earth Orbit, Geostationary Orbit.

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An Introduction to InGaAs Over InGaAs Ratio Pyrometry

This white paper covers ratio pyrometry using stacked InGaAs photodiode detectors. It explains how standard pyrometry suffers from atmospheric interference and emissivity uncertainty, then shows how a two-color sensor solves this by measuring the ratio between top and bottom detector currents. It profiles the 2C2-N17N17-T39 detector and demonstrates blackbody calibration results across the 500 to 1200°C range.