US 12,469,550 B2
Photonic content-addressable memory and applications thereof
Ghazi Sarwat Syed, Zurich (CH); and Abu Sebastian, Adliswil (CH)
Assigned to International Business Machines Corporation, Armonk, NY (US)
Filed by International Business Machines Corporation, Armonk, NY (US)
Filed on Oct. 6, 2022, as Appl. No. 17/938,373.
Prior Publication US 2024/0119999 A1, Apr. 11, 2024
Int. Cl. G11C 15/04 (2006.01); G11C 11/42 (2006.01); G11C 11/56 (2006.01)
CPC G11C 11/42 (2013.01) [G11C 11/5628 (2013.01); G11C 15/04 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A photonic content-addressable memory comprising:
a photonic cross-bar array comprising a plurality of row and column waveguides;
a plurality of photonic filter devices, each located at a respective cross-point of the row waveguides and the column waveguides for selectively coupling light from the row waveguides to the column waveguides at the cross-point, wherein each of the photonic filter devices is selectively programmable in first and second states representing respective stored bit values, and each of the photonic filter devices is operable, in said first state, to filter out light in any of a first plurality of optical states from light coupled to the column waveguides and, in said second state, to filter out light in any of a second, different plurality of optical states from light coupled to the column waveguides, wherein each of the photonic filter devices comprises a directional coupler for coupling light from the row waveguides to the column waveguides, and a programmable filter for operation in the first and second states, wherein the programmable filter comprises a frequency filter for filtering out light having any of a first plurality of wavelengths in the first state and any of a second plurality of wavelengths in the second state;
an encoder for encoding a plurality of input bit-strings into optical signals such that the stored bit values in different of the input bit-strings are encoded using the optical signals in different pairs of the first and second plurality of optical states, each of the different pairs comprising one state from each of said first and second plurality of optical states, and to simultaneously supply the optical signals corresponding to each bit-position in the input bit-strings to a respective one of the row waveguides of the photonic cross-bar array; and
a detector for detecting light in any of said first and second plurality of optical states in the column waveguides, thereby identifying any mismatch between each of the input bit-strings and the stored bit values in the photonic filter devices coupling light to the column waveguides.