Patent ID: 7684662

Claim:
An AD converter, comprising: a light source unit configured to provide an optical signal; at least one waveguide unit comprising a photonic crystal, the at least one waveguide unit being configured to receive the optical signal from the light source, and to output an output optical signal; a modulation unit configured to apply a RF signal to the at least one waveguide unit, thereby modulating the output optical signal output from the at least one waveguide unit; and a digital conversion unit configured to convert the modulated output optical signal to a digital signal, wherein the at least one waveguide unit comprises: a first waveguide; a second waveguide that is symmetrical to the first waveguide in its shape, the second waveguide being configured to share the optical signal with the first waveguide; and at least one filter arranged between the first and the second waveguides so as to direct at least a portion of the optical signal input to the first waveguide that has a specific toward the second waveguide.