Document Type : Research Paper
Abstract
Power management is a major problem for remotely deployed autonomous sensor devices especially in hard-to-reach areas such as in underwater applications. Motivated by the higher data rates and energy efficiency in optical communication systems, in addition to the low cost of the optical communication/ energy harvesting circuit components when compared to their RF counterparts, an efficient solution has been proposed in this work by transmitting a combination of power and information signal simultaneously through optical means and optimally separating the signals at the receiver. This proposed energy harvesting technique obviates the need for intermittent sensor device retrieval for battery charging or replacement. In this paper, we demonstrate this technique by transmitting a 3.5 kHz pulse position modulated signal using a laser diode at the transmitter circuit. At the receiver circuit, a solar panel is used for optical signal reception. The received signal is processed to separate the information signal from the power signal using an LC low pass filter. The results show that the amount of energy harvested is dependent on the combination of the amount of irradiant ambient light and the received signal itself on the solar panel, having the DC component of the harvested energy reaching 1.44 V. Additionally, at varying distances from the transmitter, the strength of the received signal itself was observed to be 0.27 V at 10 cm and reduced to around 0.20 V for distances between 60 cm to 150 cm. These results indicate that the strength of the actual transmitted signal reduces at longer distances from the receiver and confirm the feasibility of the proposed system.
