The coverage of large areas of photo detection is one of the crucial
elements of experiments studying high energy cosmic rays, neutrinos of
different sources as well as the possible nucleon decay. Since 2003,
we have been currently working on large photomultiplier (PMT)
developments with the Photonis Company. The main results will be
presented. A particular attention will be put on the correlation of
parameters such as the quantum efficiency versus noise or the
resolution (SER) versus after pulse rate. One of the most challenging
R&D is associated with the future experiments which plan to use water
tanks of one order of magnitude larger than the Hyper Kamiokande
one. The amount of large PMTs needed would reach impressive numbers
(more than 100,000 pieces per tank) and lead to consider new
approaches. The French "PMm2" programme proposed by three laboratories
(LAL and IPN at Orsay, LAPP at Annecy) in collaboration with Photonis
has been granted for 3 years (2007-2009). It aims to replace very
large PMTs (20") by smaller ones (12") associated in sets of 16 pieces
locally coupled to their electronics based on a multichannel ASIC
which provide digitized information (charge and time) of each PMT
associated with time stamps. The status of the project and its main
advantages will be discussed.