Ordinary digital cameras can pick up infrared, although the newer ones don't work as well because the manufacturers put in more powerful filters to block out IR. Many hobbyists use ordinary digital cameras to do infrared photography. The cheapest sort of filter to block out visible light is a piece of exposed color film (see link below). More expensive filters are available from places like Edmund Optics.
On newer cameras many people find ways to replace the built-in IR-blocking filter with a piece of clear glass. There are even companies that do this (for a price).
Visible light is usually defined as having a wavelength of 400nm to 700nm. Anything above 7000nm is infrared. The theoretical upper limit on a digital camera is about 1000nm, but the practical limit is about 825nm to 850nm.
Meanwhile, the human eye can see infrared up to about 950nm, but only if it is extremely bright. For example, many people own infrared laser pointers, the most popular wavelengths being 780nm, 808nm, and 980nm. The last one is invisible, but the first two can be seen at night in a dark room, although these laser pointers are usually 10 to 100 times as powerful as the ordinary cheap visible-light kind. You can also see the light from a 940nm flashlight, but just barely.
What you have discovered is an effect widely used by professional photographers: visible light supplemented by infrared, producing a glow that looks almost magical.