no oscilloscope. Would one be of use?
It's like saying I have legs but no shoes would they be useful.
The matched pairs refer to the wavelength of the emitter / detector these must be the same for best sensitivity.
You need the IR to be modulated to prevent interference. A friend of mine made on of these in the 60s and the wipers went every time he drove under a lamp at night.
However, most modulated IR receivers are designed for remote control and as such need modulated IR that is pulsed. You don't want these, look for those receivers designed for beam breaking like the TSOP4038.