Measurement of harmonic distortion in microwave photodetectors

The use of an offset phase-lock heterodyne system with a large dynamic range (>110 dB) for measuring photodetector (PD) harmonic distortion out to microwave frequencies is discussed. Up to 40 harmonics and second-harmonic levels only 17.8 dB below the fundamental were observed in high-speed PDs with only 1.7 mW incident. Measurements of harmonic power versus incident optical power are reported, along with associated PD bandwidth reduction.<
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