Research On The Miniature Multi-dispersion Grating Spectrometer With High-resolution

Spectrometers are important measuring instruments,and have been widely used in many fields of industrial production and scientific research.With the development of industrial technology and the improvement of scientific research level,many application fields put forward new performance requirements for spectrometers,especially for high resolution and miniaturization.In this study,research on miniature high-resolution grating spectrometer based on multi-dispersion principle is performed especially for the significant demand of channels and devices testing in dense wavelength-division multiplexing(DWDM)optical communication system.The main research contents are as follows:The developing history of spectrometers is summarized.Meanwhile,the advantages and disadvantages of different spectrometers are compared and analyzed.To meet the project requirements,spectrometer based on grating dispersion principle is selected as the basic optical structure.The spectrometers with high-resolution and miniaturization characteristics appeared in recent years are analyzed and summarized,and the principle of multi-dispersion is selected as the breakthrough point of the research.The basic principles,core devices and typical optical structures of grating spectrometers are introduced,and the main factors affecting the performance of the spectrometers are analyzed as well.Double cascade spectrometer,which has high resolution,is studied,and the problem that the current design theory of double cascade spectrometer is inconsistent with actual is pointed out.The strict theoretical model of the optical structure of double cascade spectrometer is rebuilt,and the simulation results under ideal conditions are given.Based on double cascade spectrometer,three novel optical structures of multi-dispersion grating spectrometer are proposed.For the three proposed approaches based on multi-dispersions principle,the resolution characteristics,the calibration functions and other important parameters are rigorously analyzed from the basic grating equation considering the geometrical light path of the system.Based on the theoretical analysis results,three multiple-dispersion spectrometers are designed and stimulated over a broad spectrum from 1250 nm to1650nm according to the actual demand of optical communication measurement.Theoretical analysis and simulation results show that the multi-dispersion scheme has the characteristic of high-resolution and constant,which lays a foundation for the development of real instruments.To solve the problem that diffraction efficiency of gratings under sub-wavelength working consition has polarization sensitivity,the working principle of depolarizers and its feasible conditions in this research are discussed at first.Then,the methods of rotation polarization state based on an achromatic quarter-wave plate and polarization separation reception are proposed.The theoretical analysis and designed of the two schemes are also conducted in details.Finally,by comparing the advantages and disadvantages of these three methods and considering the feasiblility in current technology level,the polarization separation reception metod is chosen for experimental prototype development.The prototype of double-dispersion spectrometer is built using the modular idea and its performances are also tested according to the actual demand.Then,based on the prototype of double-dispersion spectrometer,triple-dispersion spectrometer and quadruple-dispersion spectrometer systems are built and tested.The experimental results further prove the feasibility of using multi-dispersion method in the development of miniature high-resolution spectrometers.