In one aspect, an optical device comprises a monolithic optical module which includes a first total internal reflection (TIR) surface, a second TIR surface adjacent the first TIR surface, and a first optical port aligned with the first internal optical beam dividing interface. An interface between the first TIR surface and the second TIR surface forms a first internal optical beam dividing interface. An exterior surface of the first TIR surface and an exterior surface of the second TIR surface form a generally V-shaped notch on the monolithic optical module. A first optical beam entering the monolithic optical module through the first optical port and incident on the first internal optical beam dividing interface is partially reflected by the first TIR surface to travel in a first direction as a second optical beam and partially reflected by the second TIR surface to travel in a second direction as a third optical beam. The second direction is generally opposite to the first direction.