# Optical Logic Gates using Polarisers

I am trying to build an optical logic circuit using the horizontal or vertical orientations of light as the two binary states and laser as the source. Before I ask you my question I wanted to first share how I designed the NOT Gate.

NOT Gate To explain the working let's assume I send in a horizontally oriented beam of light. This beam splits into two beams. Because it is horizontally oriented, the first split beam won't enter the V Polarizer and gets blocked. The second split beam enters the H Polarizer and consequently gets vertically oriented at the end and the lower ldr detects the light, notifying us that it is now in V state.

My Problem Now, I am not able to figure out another combination of polarizers for AND and OR Gate. Can anyone help me in giving me a lead?

• You don't even say what the logical 0 and 1 are. How should one answer the question? – Norbert Schuch Aug 14 at 17:28
• I have mentioned that in the second and third line. Read properly. – Bhavesh Aug 15 at 18:14
• I see. (Note that "second and third line" depends on the screen!). But then, why don't you just use a lambda/2 plate for the not gate? Your setup seems unnecessarily complicated! – Norbert Schuch Aug 15 at 18:38
• I don't have access to wave plates, only linear polarizers – Bhavesh Aug 16 at 14:28

Also, you can improve your NOT gate by switching your design with a single half-waveplate oriented at 45$$^\circ$$. This new design would be 100% efficient.