Power and Data Transmission throughOptical Wireless Link with emphasis on Application for a Drone

Abstract: In the era of power-hungry mobile devices many astonishing advancements have been made but these advancements consume a lot of power and the lifetime of any such device is until the batterylasts. This limits the capability of these devices, one of the examples of such devices is "Drones". Drones provide various benefits but these benefits only last for 10-20 minutes depending on the operations it provides, if battery capacity is increased, which in turn increases the weight on drone, to prolong the life, weight aspects are to be compromised and most of the battery power is wasted to lift the battery itself. To overcome battery life problem, optical wireless power and data transfer link is investigated. To achieve this task a simplified transmitter model with blue LED as optical source and a reflector cone to focus optical power at a single point is designed. To convert optical power to current, photo diode with 300 mA/W responsivity at 450 nm wavelength is chosen based on the drone’s requirement. Upon testing, Photo diodes reach saturation current of 20 mA, when optical power >1 W is irradiated over photo diode. This saturation current is not sufficient to drive a load such as drone. To overcome this, other means to convert optical power to electricity is investigated. Peltier device can be used to absorb optical power by coating a side of Peltier with black color. A simplified Peltier model is used and when it is tested, the temperature difference of 20 degrees is observed which in turn generated 100 mV and 100 mA for <5 seconds at 1 ohm load. It is concluded that the wireless power transfer with the commercially available photo diodes is not feasible. To generate enough power to drive drone using Peltier device, temperature differential must be high and to maintain it complex mechanism is needed. To transfer power and data over a same link, existing modulation techniques used for data transfer are investigated to find effect of transferring power and data simultaneously.Effect of Modulation techniques for power and data transfer over a wireless optical link is investigatedand concluded that the effect is not drastic.