NLC: Natural Light Communication using Switchable Glass

Switchable glass, which can electronically change its state between opaque and transparent, is finding applications in modern buildings as a replacement for traditional curtains or blinds to enable dynamic privacy control in physical spaces. In this work, we propose to exploit the electronic configurability of switchable glass to modulate natural light, which can be demodulated by a nearby receiver with the light-sensing capability to realise data communication over natural light. We call this natural light communication (NLC). A key advantage of NLC is that no energy is used to generate light, as it simply modulates the existing light in nature. The slow response rate of the switchable glass, however, limits the achievable data rates for NLC. We propose and optimise an ON-OFF modulation/demodulation technique for such slow-response switchable glass and implement it using off-the-shelf Polymer Dispersed Liquid Crystal (PDLC) glass. We demonstrate that the proposed NLC can achieve 33.33 bits per second communication with a bit error rate below 1% under a wide range of ambient luminance.