An optical switch, comprising: a first optical waveguide, a first optical add path, a second optical add path and a micro-ring resonator. The micro-ring resonator is operable to add a first optical signal at a preselected wavelength received from the first optical add path to the first optical waveguide to travel in a first direction through the first optical waveguide. The micro-ring resonator is further operable to add a second optical signal at the preselected wavelength received from the second optical add path to the first optical waveguide to travel in a second direction through the first optical waveguide opposite to the first direction. There is also provided an optical drop switch, an optical switching apparatus, an optical communications network node and an optical communications network.