A fiber optic speed sensor is used for sensing the rotational speed of an N bladed fan in a turbo-machine application including a polarization-preserving optical circuit positioned adjacent the locus described by the remote ends of the blades. It has been developed, bench tested and rig tested in a real turbine airflow environment. It employs an innovative design using a pressure tube and fiber optic micro bend transducer in order to capture turbine blade pass wake frequency. A signal processor into turbine rotational speed can convert the blade pass frequency. The FOSS offers unique potential to meet future requirements for performance (0 to 25KHz) and environmental tolerance.

Fiber optic switches are routing an optical signal without electro-optical and opto-electrical conversions. It can interface with two types of cables, single mode and multimode.  Single mode is an optical fiber that will allow only one mode to propagate. The fiber has a very small core diameter of approximately 8 µm. It permits signal transmission at extremely high bandwidth and allows very long transmission distances. Some fiber optic switches can be used for both single mode and multimode cables.