[Laser] Chinese professor builds optical communications system with retail parts

[bernieS]

http://www.networkworld.com/news/2013/110513-chinese-professor-builds-li-fi-system-275605.html

Chinese professor builds Li-Fi system with retail parts

By Michael Kan, IDG News Service
November 05, 2013 07:07 AM ET

IDG News Service - The equipment is big and expensive, with the 
research costs at almost $500,000. But by just using retail 
components, Chinese professor Chi Nan has built her own Li-Fi 
wireless system that can use LED lights to send and receive Internet data.

"I bought the lights from Taobao," she said, referring to the Chinese 
e-commerce site.

The professor from Fudan University showed off the technology on 
Tuesday at the China International Industry Fair in Shanghai. Unlike 
traditional Wi-Fi routers that use radio signals, Chi's system relies 
on light to send and receive data wirelessly.

Others scientists, 
<http://news.techworld.com/networking/3423930/strathclyde-university-develops-led-li-fi-internet-connections/>especially 
in the U.K., have also been researching the technology, and dubbed it 
"Li-Fi". But rather than develop specialized hardware, Chi bought 
off-the-shelf retail parts to create her system.

Chi, an expert on optical fibers, said on the side lines of the trade 
show that she was simply interested in the promise of Li-Fi. "I just 
wanted to play around," she said. Funding also came from the local 
Shanghai government, which has made research in the area a goal.

While Li-Fi is still in its early stages, the technology could 
provide an alternative to using radio waves for wireless Internet 
access. Currently, household Wi-Fi routers and mobile 
telecommunication towers depend on radio signals to send data 
wirelessly. But the amount of radio spectrum is limited.

Li-Fi, however, could be deployed in everyday LED bulbs, with 
light-based Internet connections covering the interior of entire 
homes or buildings. The data connection speeds can also reach several 
gigabits per second. Chi's own system runs at 150 Mbps by using a 
small number of LED bulbs each at one watt.

"With a more powerful LED light, we can reach 3.5 Gbps speeds," she 
added. Both the router and receiver are fitted with LED bulbs so that 
they can send data, and also installed with a chip that can process 
the signals.

But Li-Fi isn't without its drawbacks. Because it is dependent on 
light, the technology can't penetrate walls or work in complete 
darkness. In Chi's case, the Li-Fi receiver must be within three 
meters of the router, and placed under the LED bulbs so that the 
sensor can read it.

In addition, her system is not exactly portable. The first model is 
quite large, with the Li-Fi receiver itself is about the size of a 
video game console. A second model was made to compact the parts, and 
that Li-Fi receiver resembles closer to a mini desktop PC. On 
Tuesday, the receivers were shown connected to two nearby laptops via 
ethernet cable.

"There are still many problems that need to be resolved," Chi said, 
pointing to the need to improve the Li-Fi coverage, and miniaturize 
the needed components.

Over time, however, the Li-Fi receiver could conceivably take the 
form of a USB dongle that attaches to a notebook. Chi estimates it 
will take another five years before the technology can enter the 
market as consumer products. So far, her team has spent about 18 
months on the project.