Design Of Front-end Coupling Optical System For The Integrated Chip Spectrometer

In recent years,the development of integrated chip spectrometers has solved a series of the problems caused by the large size of traditional spectrometers,and beam coupling has determined the working efficiency of spectrometers.Integrated chip spectrometer beam coupling causes a series of problems,such as chip wear,size mismatch,and low coupling efficiency.Especially when the integrated chip spectrometer has a linearly discrete waveguide structure at the receiving end,direct beam coupling will lead the energy waste of waveguide gap.Furthermore the edge position waveguide receives no energy,which will reduce energy utilization and coupling efficiency.In this paper,a non-contact front-end coupling optical system is designed to match a new integrated chip spectrometer.The Gaussian beam is shaped into an anti-Gaussian beam,so that the edge position waveguide can receive enough energy.The beam expanding system is used to match the beam aperture.The microlens array is used to discretely couple the beam to the corresponding waveguide to improve the coupling efficiency.And the cylindrical lens is used to compress the light,matching linear distributed waveguides.Finally,the fiber beam is discretely imaged on the integrated chip spectrometer in the 380nm-780 nm,enabling the edge waveguide to receive sufficient energy response.The system structure is simple and requires no adjustment,which provides a new idea and new method for the research of the integrated chip spectrometer coupling method.In addition,based on the coupling optical system of integrated chip spectrometer,this paper also designs a matched coupling monitoring system.By using the shared optical path,the alignment of the light spot and the waveguide array is monitored while the beam is coupled.Therefore,the integrated chip spectrometer achieves better coupling effect.Finally,the paper calculates and analyzes the coupling efficiency of the designed coupling optical system.Analysis shows that the coupling effect is much better,and the coupling efficiency is improved to 2.57 times,compared with the traditional coupling method.Therefore,the system designed in this paper effectively solves the low coupling efficiency of the discrete linear waveguide integrated chip spectrometer,which has important guiding significance in practical engineering applications.