US 11,868,026 B2
Optical AD converter and optical receiver
Tomoyuki Akiyama, Yokohama (JP); Takeshi Hoshida, Kawasaki (JP); Jun Matsui, Kawasaki (JP); and Shinsuke Tanaka, Hiratsuka (JP)
Assigned to FUJITSU LIMITED, Kawasaki (JP)
Filed by Fujitsu Limited, Kawasaki (JP)
Filed on Aug. 17, 2022, as Appl. No. 17/889,951.
Claims priority of application No. 2021-177000 (JP), filed on Oct. 28, 2021.
Prior Publication US 2023/0136573 A1, May 4, 2023
Int. Cl. G02F 7/00 (2006.01); G02F 1/313 (2006.01)
CPC G02F 7/00 (2013.01) [G02F 1/3137 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An optical analog-to-digital (AD) converter comprising:
wherein the optical AD converter converts an analog signal of information included in inputted signal light into a digital signal, and is formed of N stages corresponding to a number N of bits of the digital signal,
optical waveguides configured to respectively guide the signal light, base light obtained by branching local light, and reference light obtained by branching the local light;
a light receiver configured to detect and compare light levels of the signal light and the reference light, and output a binary comparison result; and
an optical modulator configured to variably control a light level of the base light, based on the binary comparison result, in each stage of the N stages,
wherein an output variably controlled of the optical modulator is multiplexed with the reference light of a next stage.