Speaker
Description
Summary
The detector systems currently being produced and installed in the LHC experiments
all rely heavily on the optical transmission of both readout and control data. Data
rates for transmission between the counting rooms and the detectors currently reach
up to 1.6Gb/s for radiation-tolerant data links. The upgrading of the LHC luminosity
at Super LHC (SLHC) will lead to an increase of the particle interaction rate and
thus to an increase in the amount of data to be transmitted by the detector readout
systems. It is thus pertinent to assess the possibilities of increasing the data
transmission speeds available on individual optical data channels. With the target
of reading-out an upgraded Tracker of the CMS detector at SLHC, we have begun
evaluation of commercial data transmission components operating at the emerging
10Gb/s data transmission protocols such as 10Gigabit Ethernet (10GbE).
Standardization within the telecom and datacom industry has led to a Multi-Source
Agreement (MSA) for a small formfactor transceiver of type XFP. The XFP MSA Group
has created a specification for a module, cage hardware, and IC interfaces for a 10
Gb/s hot-pluggable module converting serial electrical signals to serial optical
signals.
The specification aims to be protocol-agnostic, operating over a range of bit-rates
(9.95 – 11.1 Gb/s). This range would allow the matching of rates derived from a
40MHz or 80MHz bunch-crossing frequency at SLHC.
The measurement protocols, including eye-diagram measurements, required to assess
the performance of such highspeed data links will be outlined. These will be
decomposed into measurements pertaining primarily to the system, the transmitter
and the receiver parts. Data will be shown for COTS XFP samples. Finally, the
requirements for operation will be outlined and compared to the typical environment
found in currently implemented optical data transmission systems in HEP.
