It occurred to me that it ought to be possible to make a vacuum tube which, instead of a heater, uses an intense light source, such as a laser, to kick electrons off of the cathode through the photoelectric effect instead of them being excited using a heated filament. I am aware that two terminal evacuated tubes have been made, using the photoelectric effect to sense light and its wavelength too (as in Einstein's experiment). However, this device would have one or more grids, a plate (anode), and a cathode just like a typical amplifying vacuum tube, the only difference being a light source in place of a heater. Would this:
A. Be possible?
B. Be practical? (at least to the extent to which a vacuum tube is practical at all)
C. Has it been done?
I cannot find anything about this using Google, some lab equipment is taking precedence over the results I am looking for, if they exist.
Here is a functional diagram:
Here are the first drawings I made of the device. The scans aren't so great, but it shows my original concept and a proposed Class B amplifier, as an example of an application which almost certainly would never work. Connections points A and B are an incoming audio signal. C is a connection to voltage supply. D is power for the lasers. I suspect that the laser diodes ought not be connected in parallel as is shown, but I didn't think of that while drawing this. Perhaps it is okay.