There are a number of devices capable of analysing Infra Red communications.
The most simple are an Oscilloscope with a phototransistor - and a little circuitry, right up to complex protocol analysers, which can analyse the timing, the baud rate - and shift in the data to registers.

All Infra Red devices are digital serial devices, which simplifies things somewhat.

If you want some makeshift detection just to see if it is working, a CCD based camera, like a webcam will be able to detect it, it will show as bright white or red flashes from its origin.