What do you want to do with each waveband? You can reject the IR with a reflective glass shield over the lens. But that will lose the IR. If you want to collect it and heat something up, then you might consider putting an IR reflector near the target and using the focussed IR there.
Actually we are trying to use IR part for laser pumping and Visiable part for lightning in building (Such as multistory buildings) by guiding it using fiber bundle. For as of now we are looking for extincting the visible part which is causing heat in our designed solar pumped Laser system.
A silicon window would absorb the visible and pass the IR, but it will get very hot. I think you will want to purchase a custom dichroic that separates Vis/IR using multi-layer deposition of dielectrics on a transparent substrate. This is called a 'cold mirror'. You can get them from Edmunds, or Thorlabs, or any optical supplier.
depending on the spectrum you want to have you can also use cut off filters. Here you can get an impression: http://www.itos.de/en/schott-optical-filters/long-pass/rg9/ I am sure that the Itos people will be able to help you further.