CHARACTERIZATION STUDY OF A FIBER BASED SPECTROMETER AS AN EFFECTIVE NEXT GENERATION SPECTROMETER SYSTEM

A standard Multimode optical fiber can be used as a general purpose spectrometer after calibration the wavelength dependent speckle patterns produced by interference between the guided modes of the fiber. A theoretical analysis of the effects of the fiber geometry on the spectrometer performance, and then presents a reconstruction algorithm using a transmission matrix. Both fiber geometry and length have an effect on the spectral resolution and bandwidth, as well as the additional limitation on the bandwidth imposed by speckle patterns contrast reduction when measuring dense spectra is investigated. In a multimode fiber spectrometer, the interference between the guided modes creates a wavelength-dependent speckle patterns, providing the required spectral-to-spatial mapping. The advantage of using an optical fiber is that a long propagation length is easily achieved with minimal loss, giving high spectral resolution. Furthermore, the fiber-based spectrometer requires only a multimode fiber and a monochrome CCD camera to record the speckle patterns. Compared to traditional spectrometers, optical fibers are lower cost, lighter weight, and can be coiled into a small volume and providing spectral resolution that is competitive with state-of-the-art grating based spectrometers