Optical logic gates and method for generating logic signals using DNA-based nanostructure

An optical logic gate, comprising:

• a DNA-based nanostructure comprising DNA and metal nanoparticles coupled to the DNA, and configured to rotate a polarization plane of an incident light, wherein a rotation angle (θ) of the polarization plane is greater than 0 degrees and less than 90 degrees, and wherein the rotation angle (θ) of the polarization plane by the DNA-based nanostructure is influenced by:
• a kind, length, sequence, or rotating direction of a helix of the DNA of the DNA-based nanostructure,
• a kind, length, or distance between metal nanoparticles coupled to the DNA of the DNA-based nanostructure, or
• a combination thereof;
• a polarizer disposed incident to light passing through the DNA-based nanostructure, and configured to extract a component of light in a direction of a predetermined reference axis, from light having a polarization plane rotated by the DNA-based nanostructure;
• and
• a detection unit disposed incident to light passing through the polarizer, and configured to generate a logic signal based on a result obtained by comparing the intensity of the component of light in the direction of the reference axis extracted by the polarizer with a predetermined threshold value,
• wherein the rotation angle (θ) of the polarization plane of light by the DNA-based nanostructure is expressed by the following equation:
• θ=k×CdA,
• wherein C represents a concentration in a liquid sample, or an area density in a solid sample, of the DNA-based nanostructure,
• wherein d represents a distance for the light to pass through the DNA-based nanostructure,
• wherein A represents a sectional area of light passing through the DNA-based nanostructure, and
• wherein k is a polarization effect constant according to a property of the DNA-based nanostructure.