This paper presents a low-power and low-complexity data receiver circuit suitable for solar-cell-based optical receivers. The receiver circuit is based on a data slicer that has been modified to work while directly tied to a solar cell as the photo-transducer element. The receiver circuit uses a first-order RC high-pass filter to remove the solar cell’s DC voltage induced by ambient light and a comparator along with a voltage-averaging circuit to extract digital waveforms. A circuit analysis and experimental results are presented. The power consumption of the presented implementation of the receiver circuit is 6.28 μW and during tests, it achieved error-free transmission at a speed of 133 bps at a distance of 30 cm. This receiver circuit could be used as a wake-up receiver for solar-powered wireless devices or to transmit low-bandwidth command messages in visible-light optical communication applications.

A circuit for solar cell photo-luminescence modulation is presented. The circuit comprises a MOSFET, an opamp and a resistor forming a feedback loop that sets the current through the solar cell proportional to a modulating input voltage. The proposed modulator circuit achieves higher linearity than other photo-luminescence modulators making it suitable for direct amplitude modulation. A proof-of-concept prototype to demonstrate an optical link with a GaAs solar cell resulting in a bit error rate of 2.74×10-3using 6-ary pulse amplitude at a speed of 64.62 kbps.

This paper presents a photosynthetically active radiation (PAR) sensor based on an 18-band spectral sensor chipset with integrated optical filters. PAR sensors are an important tool for farmers and the proposed solution offers a path to low- cost PAR sensors. A technique for correcting the optical spectral leakage in the spectral sensor chipset is proposed and is applied to measurements collected indoors and outdoors. Tests results show that the proposed sensor and leakage-correction technique outperform lab-grade commercially-available PAR sensors.