Photonic down‐converters or Electrical to Optical Convertor Module is a flexible alternative to conventional RF mixing schemes thanks to their broad‐bandwidth capabilities, flexibility regarding input and output frequency range, EMI free operation, spurious‐free nature and reduced SWaP in particular for optical WDM architectures. In OPTIMA, a photonic downconverter based on the use of external modulators will be developed and demonstrated up to TRL6. Its performance will be optimized in order to ensure that current standard performance required for operation in analogue transparent satellite links is measured in the OPTIMA demonstrator. The downconverter will be comprised of a Mach‐Zehnder modulator acting as mixer and the corresponding Ka band RF stages (amplifiers, filters …). The photonic down-converting unit will be based on the scheme already developed by DAS but achieving a higher integration with 50% reduction in weight and size. The design of the assembly will be aimed at achieving a high potential of integration exploring the potential for parallel device arrangements aiming at high number of optical carriers and LO signals.