An optical buffer and a method for storing an optical signal using the optical buffer, where the optical buffer includes a first waveguide, a first optical delay waveguide loop and a controller. The first waveguide includes a first arm and a second arm, where a first end of the first arm is an input end of the optical buffer, and a second end of the second arm is an output end of the optical buffer. A second end of the first arm connects to a first end of the second arm. The first optical delay waveguide loop connects to the first arm at a first end using a first optical switch, and a second part of the first optical delay waveguide loop connects to the second arm at a second end using a second optical switch. The controller connects to the first optical switch and the second optical switch respectively.