LED-based white light

Is blue optical filter necessary in high speed phosphor-based white light LED visible light communications?

Optical blue filter is usually regarded as a critical optical component for high speed phosphor-based white light emitting diode (LED) visible-light-communication (VLC). However, the optical blue filter plays different roles in VLC when using modulations of on-off keying (OOK) or discrete multi-tone (DMT). We show that in the DMT VLC system, the blue optical filter may be unnecessary, and even ...

Improvement of light quality by DBR structure in white LED.

This study demonstrates the application of DBR structure into the remote phosphor structure to improve the angular correlated color temperature (CCT) deviation in white light-emitting diodes (WLEDs). In the experiment, the LED device with DBR structure yielded a higher luminous efficiency than a conventional structure. The CCT deviation can be improved from 1758K to 280K in a range of -70 to 70...

Phosphor-Based White Light Emitting Diode (LED) for Vertical Scanning Interferometry (VSI)

Output blue light evaluation for phosphor based smart white LED wafer level packages.

This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The max...

Real-time white-light phosphor-LED visible light communication (VLC) with compact size.

In this demonstration, we first demonstrate a real-time phosphor-LED visible light communication (VLC) system with 37 Mbit/s total throughput under a 1.5 m free space transmission length. The transmitter and receiver modules are compact size. Utilizing our proposed pre-equalization technology, the ~1 MHz bandwidth of phosphor LED could be extended to ~12 MHz without using blue filter. Thus, the...