I searched for some information regarding LED's and found out that they can only go one way because of the two metals inside of the LED have 2+/- electrons making it easy to go one way but difficult to go the other way. This got me thinking about valves. When valves are open you can also squeeze to the other side! So I was wondering if it is possible to excite an LED(through a laser beam or something similar) to allow current to flow to the opposite "allowed" direction.
Setup:
**+** = **+**
**|<|**= LED
**-** = **-**
--- = wire
LOAD=LOAD
I'm so clever. I know.
Laser beam shooting photons at LED
**+** --- **|<|** --- LOAD --- **-**
I tried googling this kind of information but it appears that no one has really thought about it. Or I'm a bad googler.
Best Answer
Yes, an LED will conduct in reverse if excited by an optical signal (of the right wavelength). This is basically just using an LED as a photodiode. Any reference on photodiodes will explain the underlying physics.
In fact, pretty much any diode will have this behavior. However, silicon diodes are typically packaged in opaque encapsulents to avoid the photoelectric effect producing significant reverse conduction. Also, photodiodes designed as photodiodes will be optimized to maximize the effect, while LEDs will not be.