20 research outputs found
A compact ultranarrow high-power laser system for experiments with 578nm Ytterbium clock transition
In this paper we present the realization of a compact, high-power laser
system able to excite the Ytterbium clock transition at 578 nm. Starting from
an external-cavity laser based on a quantum dot chip at 1156 nm with an
intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of
visible light at 578 nm via frequency doubling. The laser is locked with a 500
kHz bandwidth to a ultra-low-expansion glass cavity stabilized at its zero
coefficient of thermal expansion temperature through an original thermal
insulation and correction system. This laser allowed the observation of the
clock transition in fermionic Yb with a < 50 Hz linewidth over 5
minutes, limited only by a residual frequency drift of some 0.1 Hz/s
IEEE 802.15.7-Compliant Ultra-low Latency Relaying VLC System for Safety-Critical ITS
The integration of Visible-Light Communications technology (VLC) in
Intelligent Transportation Systems (ITS) is a very promising platform for a
cost-effective implementation of revolutionary ITS and cooperative ITS
protocols. In this paper, we propose an infrastructure-to-vehicle-to-vehicle
(I2V2V) VLC system for ITS, implementing it through a regular LED traffic light
serving as a transmitter and a digital Active Decodeand- Relay (ADR) stage for
decoding and relaying the received information towards further incoming units.
The proposed VLC system targets the challenging and important case of ultra-low
latency ADR transmission of short packets, as this is needed for emerging
applications of automatic braking, car platooning and other critical automatic
and/or assisted driving applications. The experimental validation of the ADR
VLC chain, as well as a thorough statistical analysis of errors distribution in
the transmission, has been performed for short to medium distances, up to 50
meters. The performances of the designed system are evaluated by measuring the
packet error rate (PER) and latency in the whole ADR transmission chain. Our
analysis shows that our system attains ultra-low, sub-ms latencies at 99.9%
confidence level for PER as high as 5 x 10^-3, yet granting a latency below 10
ms even for distances of 50 m. The demonstrated system prototype is compatible
with IEEE 802.15.7 standard
Experimental measurements of a joint 5G-VLC communication for future vehicular networks
One of the main revolutionary features of 5G networks is the ultra-low
latency that will enable new services such as those for the future smart
vehicles. The 5G technology will be able to support extreme-low latency. Thanks
to new technologies and the wide flexible architecture that integrates new
spectra and access technologies. In particular, Visible Light Communication
(VLC) is envisaged as a very promising technology for vehicular communications,
since the information can flow by using the lights (as traffic-lights and car
lights). This paper describes one of the first experiments on the joint use of
5G and VLC networks to provide real-time information to cars. The applications
span from road safety to emergency alarm
Efficient frequency doubling at 399 nm
We describe a reliable, high-power, and narrow-linewidth laser source at 399 nm, which is useful for cooling and trapping of ytterbium atoms. A continuous-wave titanium-sapphire laser at 798 nm is frequency doubled using a lithium triborate crystal in an enhancement cavity. Up to 1.0 W of light at 399 nm has been obtained from 1.3 W of infrared light, with an efficiency of 80%