Prototyping of a 25 Gbps optical transmitter for applications in high-energy physics experiments

TL;DR

This paper presents the development and testing of a miniature optical transmitter, MTx+, capable of 25 Gbps data transmission using VCSELs and a high-speed laser driver, suitable for high-energy physics experiments.

Contribution

It introduces a novel 25 Gbps optical transmitter prototype with radiation-tolerant components and demonstrates successful high-speed data transmission in a compact design.

Findings

Achieved 25 Gbps data rate with eye-diagram mask margin of 22%

Successfully upgraded the prototype with radiation-tolerant components

Demonstrated reliable operation in high-energy physics environments

Abstract

Development of optical links with 850 nm multi-mode vertical-cavity surface-emitting lasers (VCSELs) has advanced to 25 Gbps in speed. For applications in high-energy experiments, the transceivers are required to be tolerant in radiation and particle fields. We report on prototyping of a miniature transmitter named MTx+, which is developed for high speed transmission with the dual-channel laser driver LOCld65 and 850 nm VCSELs packaged in TOSA format. The LOCld65 is fabricated in the TSMC 65 nm process and is packaged in the QFN-40 for assembly. The MTx+ modules and test kits were first made with PCB and components qualified for 10 Gbps applications, and were tested for achieving 14 Gbps. The data transfer rate of the MTx+ module is investigated further for the speed of up to 25 Gbps. The LOCld65 is examined with post-layout simulation and the module design upgraded with components including the TOSA qualified for 25 Gbps applications. The PCB material is replaced by the Panasonic MEGTRON6. The revised MTx+ is tested at 25 Gbps and the eye-diagram shows a mask margin of 22 %.