Fiber optical interferometer for spectral analysis

The realization of an optical spectrum analyzer for 1200-1700 nm that is based on a fiber-optical Michelson interferometer is described. The advantage of this method over traditional interferometers with bulk optics is the compact and stable setup, which needs no further adjustment. In addition, the use of standard single-mode fiber and coupler yields a less expensive measurement device. The sweep time of this interferometer is 1.2 s and is limited by the used hardware. At the moment a system bandwidth of 0.4 nm can be reached. It can be increased by simple steps, e.g, by a push-pull lengthening of the reference fiber.<>