Tomas Stratil

Broadband over Visible Light: High power wideband bias-T solution

Broadband over Visible Light (BVL) is a new trend in research that combines technological principles of VLC during duplex communication between the source of optical radiation and the receiver on the side of the user and utilization of a chipset of the technology Broadband over Power Line (BPL), including provision of connectivity on power conductors. The use of the technology Bias-T proves to be a highly efficient concept of the VLC modulator. The article deals with the design of a high power broadband Bias-T allowing the use of the BVL technology at large SMD LED matrices or matrices containing power LED. The designed Bias-T was created and its functionality verified using a network analyzer and the software-defined radio.

Position of light sources for VLC

White LED diodes are increasingly used. Thanks their features they are also used for illumination and gradually replace the classical light bulbs and fluorescent tubes. The one of advantages of white LED diodes is their availability for the Visible Light Communication. This article deals with study of suitable placing of light sources for indoor. The aim is a uniform light distribution and thereby a uniform distribution of VLC data signals. There were created light sources with LED diodes in software LightTools. These light sources were placed on the ceiling of room. The simulation found the positions of light sources in which the light distribution was the most uniform.

Phosphor decay measurement and its influence on communication properties

The communication properties of the white Light Emitting Diodes (LED) above all depend on a phosphor decay. This article describes the measurement of rise and fall times of white light created by the blue LED and the YAG:Ce phosphors. Measured rise and fall times are compared to rise and fall time of the blue LED. We tested four kinds of phosphors which are able to create a white light. The phosphors were mixed in Poly-Di-Methyl-Siloxane (PDMS) polymer in the same concentration 1∶35.

Analysis of creating an innovative micro-lens made of polydimethylsiloxane polymer on the end of the optical fibers

The article describes a method for fabrication of polymer optical micro-lenses using polydimethylsiloxane (PDMS) at the end of optical fibers. PDMS is an optically clear substance having a refractive index very similar to the optical fibers. Therefore it is an interesting material for optical purposes. PDMS is characterized by resistance to electromagnetic interference (EMI), enabling the use in electromagnetically noisy environments. These lenses could be used for example for the security applications. For the manufacture of the micro-lenses is used Sylgard silicone elastomer 184. When applied to the end of conventional optical fiber is cured by treatment at 100 °C ± 5 °C. Authors performed a series of experimental measurements. The optical characteristics of the treated fibers compared with conventional fibers without micro-lenses. The fibers provided with optical lenses made of PDMS may be used for security applications, in the visible light communication (VLC) or as a microprobe.

Design and testing of high power wideband Bias-T for broadband over visible light using software-defined radio

Visible Light Communication (VLC) represents a progressively developing communications technology. This technology uses optical radiation in the visible range in order to illuminate a given area also for the communication purposes (download). One of the conditions of using the technology is the construction of a VLC modulator. The use of the technology Bias-T proves to be a highly efficient concept of the VLC modulator. Broadband over Visible Light (BVL) is a new trend in research that combines technological principles of VLC during duplex communication between the source of optical radiation and the receiver on the side of the user and utilization of a chipset of the technology Broadband over Power Line, including provision of connectivity on power conductors. The article deals with the design of a high power broadband Bias-T allowing the use of the BVL technology at large SMD LED matrices or matrices containing power LED. The designed Bias-T was created and its functionality verified using a network analyzer and the software-defined radio.