Research and design of LED indoor positioning system

According to indoor positioning requirements, the light intensity sensing circuit is designed with LED as the light source. The function relationship between light intensity and distance is obtained by fitting the experimental data. The distance from the light source to the node to be located is calculated. The coordinate position of the node to be measured on the two-dimensional plane is obtained through the trilateral measurement and positioning algorithm. The experimental results of this system show that the absolute position error is less than 10cm, which can meet the needs of a large number of indoor positioning applications.

Lasing Enhanced Surface Plasmon Resonance Sensing

The resonance phenomena of surface plasmons has enabled development of a novel class of noncontact, real-time and label-free optical sensors, which have emerged as a prominent tool in biochemical sensing and detection. However, various forms of surface plasmon resonances occur with natively strong non-radiative Drude damping that weakens the resonance and limits the sensing performance fundamentally. Here we experimentally demonstrate the first lasing-enhanced surface plasmon resonance (LESPR) refractive index sensor. The figure of merit (FOM) of intensity sensing is ~84,000, which is about 400 times higher than state-of-the-art surface plasmon resonance (SPR) sensor. We found that the high FOM originates from three unique features of LESPR sensors: high-quality factor, nearly zero background emission and the Gaussian-shaped lasing spectra. The LESPR sensors may form the basis for a novel class of plasmonic sensors with unprecedented performance for a broad range of applications.