The international collaboration designing and constructing the Deep
Underground Neutrino Experiment (DUNE) at the Long-Baseline Neutrino Facility
(LBNF) has developed a two-phase strategy for the implementation of this
leading-edge, large-scale science project. The 2023 report of the US Particle
Physics Project Prioritization Panel (P5) reaffirmed this vision and strongly
endorsed DUNE Phase I and Phase II, as did the previous European Strategy for
Particle Physics. The construction of DUNE Phase I is well underway. DUNE Phase
II consists of a third and fourth far detector module, an upgraded near
detector complex, and an enhanced > 2 MW beam. The fourth FD module is
conceived as a 'Module of Opportunity', aimed at supporting the core DUNE
science program while also expanding the physics opportunities with more
advanced technologies. The DUNE collaboration is submitting four main
contributions to the 2026 Update of the European Strategy for Particle Physics
process. This submission to the 'Detector instrumentation' stream focuses on
technologies and R&D for the DUNE Phase II detectors. Additional inputs related
to the DUNE science program, DUNE software and computing, and European
contributions to Fermilab accelerator upgrades and facilities for the DUNE
experiment, are also being submitted to other streams.