Does Ruby Emit Red When Illuminated with Green Light?

[Topher925]

If you have a phosphor such as ruby (Cr:Al₂O3) and you excite it with a light source near its main pump band (~556nm) then you should see emit light with a difference in color from the source light, correct? For example if I shined a green light onto this piece a ruby, it should appear red should it not? Or, does the light source need to be removed in order to see the shifted emitted light? I know this is probably a stupid question but I really need a sanity check right now.

 

[Andy Resnick]

Within a laser cavity, the pump light is always on; the endmirrors take care of spectrally filtering the laser light. Look at how diode-pumped Nd:YAGS are set up, for example.