Fiber, lens and sensor arrays and their precision alignment for optical devices with free space light propagation is disclosed Fabrication methods of arrays and their assembly are also proposed. In one implementation, a device includes a fiber alignment module holding fibers in parallel to form a fiber array. The fiber alignment module includes first and second alignment plates, and a spacer plate engaged between the first and the second alignment plates. Each alignment plate includes an array of through holes to respectively hold the fibers. A lens array can be engaged to the fiber alignment module to align lenses to their corresponding fibers. Passive alignment features may be formed at interfacing surfaces of different layers to assist the alignment. Applications of these integrated fiber, lens and sensor arrays to optical cross connect switches and reconfigurable add drop multiplexers are also disclosed.