Feasibility of Using Bandwidth Efficient Modulation to Upgrade the CMS Tracker Readout Optical Links

TL;DR

This paper evaluates the feasibility of upgrading the CMS Tracker optical links with bandwidth-efficient digital modulation to handle increased data rates for the Super LHC, considering hardware, environment, and R&D challenges.

Contribution

It provides a comprehensive assessment of implementing QAM-based optical link upgrades for high-energy physics data readout at CERN.

Findings

Achievable data rate with QAM is ~3-4 Gbit/s.

Hardware implementation complexity is manageable.

Technological feasibility and R&D efforts are outlined.

Abstract

Plans to upgrade the LHC after approximately 10 years of operation are currently being considered at CERN. A tenfold increase in luminosity delivered to the experiments is envisaged in the so-called Super LHC (SLHC). This will undoubtedly give rise to significantly larger data volumes from the detectors, requiring faster data readout. The possibility of upgrading the CMS Tracker analog readout optical links using a bandwidth efficient digital modulation scheme for deployment in the SLHC has been extensively explored at CERN. Previous theoretical and experimental studies determined the achievable data rate using a system based on Quadrature Amplitude Modulation (QAM) to be ~3-4Gbit/s (assuming no error correction is used and for an error rate of ~10-9). In this note we attempt to quantify the feasibility of such an upgrade in terms of hardware implementation complexity, applicability to the high energy physics (HEP) environment, technological feasibility and R&D effort required.