Mixing characteristics of InGaAs metal–semiconductor–metal photodetectors with Schottky enhancement layers

We report on the optoelectronic (OE) mixing characteristics of a Schottky-enhanced InGaAs-based metal–semiconductor–metal photodetector (MSM–PD). The measured frequency bandwidth of such a mixer is less than that of a corresponding photodetector. The mixing efficiency depends on the light modulation, local oscillator, and mixed signal frequencies and decreases nonlinearly with decrease in optical power. This is not observed in GaAs-based and non-Schottky-enhanced InGaAs MSM–PDs. We present a circuit model of the OE mixer to explain the experimental results.