xpyttl wrote:
Other than being black, that thing looks suspiciously like an LED, so I
would go for an IR LED.

You could apply power it to as you would an LED (using a
current-limiting resistor), and take a look at it in a digital camera's
display. Digital cameras are somewhat sensitive to IR, even though they
usually have a built-in IR cut filter. Try it with an IR remote control
to see what I mean.

Dan, KB1RT