Sensors & Transducers, Vol. 185, Issue 2, February 2015, pp. 78-83 78 Sensors & Transducers © 2015 by IFSA Publishing, S. L. http://www.sensorsportal.com UV-VIS-NIR Communication with a-SiC:H Tandem Device * Vitor Silva, Paula Louro, Manuel A. Vieira, Isabel Rodrigues, Manuela Vieira Electronics Telecommunication and Computer Department ISEL – Instituto Superior de Engenharia de Lisboa, Lisboa, Portugal CTS-UNINOVA, UNL - Universidade Nova de Lisboa, Caparica, Portugal * E-mail: vsilva@deetc.isel.ipl.pt Received: 14 November 2014 /Accepted: 15 January 2015 /Published: 28 February 2015 Abstract: Ultra-violet steady state illumination increases the spectral sensitivity of a pi’npin photodiode. Increased sensitivity in the range of 400-850 nm is experimentally demonstrated. The pi’npin photodiode can be illuminated on both back and front sides. Under front ultra-violet irradiation the gain is high for wavelengths in the 500-850 nm range and strongly quenches the 400-500 nm range. Under back ultra-violet irradiation the gain is high in the 400-500 nm range and strongly quenches for wavelengths in the 500-850 nm range. Using back or front illumination and the relative gain of each wavelength in the 400-850 nm range it is possible to select different wavelength channels. Results show that using different communication channels in the ultra-violet, visible and near infrared ranges the sensor exhibits a multiplexed output of all channels. By selectively illuminating the device with ultra-violet on the back or front sides of the device it enables the demultiplexing retrieval of all channels. Copyright © 2015 IFSA Publishing, S. L. Keywords: Ultra-Violet, UV, Visible, Near Infrared, NIR, Visible Light Communication, SiC technology. 1. Introduction Light-emitting Diode (LED) is a very effective lighting technology due to its high brightness, long life, energy efficiency, durability, affordable cost, optical spectrum and its color range for creative use. Their use as communication devices with a photo- diode as receptor, has been used for many years in hand held devices, to control televisions and other media equipment, and with higher rates, between computational devices [1]. This communication path has been used in the near infra-red (NIR) range, but due to the increasing LED lighting in homes and offices, the idea to use them for visible light communications (VLC) is present in many working groups. The Institute of Electrical and Electronics Engineers (IEEE) task group 7 has come up with the IEEE 802.15.7 VLC PHY/MAC standard proposal for the physical (PHY) and medium access control (MAC) for VLC communications [2]. The Internet use and its most popular protocols also have been studied for their performance over VLC [3]. Economic issues that will eventually guide the VLC outcome are also on the run [4]. The sensor presented in this paper, is based on amorphous silicon carbon technology (a-SiC:H) [5], it consists of a pi’npin structure. The front pi’n is thinner and has carbon a-SiC:H in the intrinsic layer while the back pin is based on a-Si:H. Two electrical optically transparent contacts interface the sensor at the front and back. Due to the asymmetric lengths of each pin structure and to their difference in materials, the sensor has http://www.sensorsportal.com/HTML/DIGEST/P_2605.htm