  After Run III the ATLAS detector will undergo a series of upgrades to cope
with the harsher radiation environment and increased number of proton
interactions in the High Luminosity- LHC. One of the key projects in this suite
of upgrades is the ATLAS Inner Tracker (ITk). The pixel detector of the ITk
must be read out accurately and with extremely high rate. The Optosystem
performs electro-optical conversion of signals from the pixel modules. This
paper presents recent results related to the performance of the data
transmission chain with a focus on the Optoboards and to the design, testing
and production of the Optopanels.
