Data Acquisition & Processing System For Measuring Holographic Spectra Of Optical Waveguide Devices

Optical waveguide devices are widely used in communication,sensing and biomedical fields,and play an irreplaceable role.The holographic response spectrum of optical waveguide device contains the amplitude and phase response spectrum,which carries the structure and function characteristics of the device,and can be used for the analysis,design and reconstruction of optical waveguide device.A low coherence holographic response spectrum measurement method based on double Michelson interferometer and Fourier transform is studied in this laboratory,which can simultaneously measure the amplitude and phase response spectra of optical waveguides.The data acquisition and processing subsystem is the most important part of the optical waveguide holographic response spectrum measurement system based on this method.Optical waveguide holographic response spectrum measurement system requires multi-channel,high precision,high resolution,large amount of data,high-speed/real-time data acquisition and processing.Therefore,according to the characteristics and requirements of optical waveguide holographic response spectrum measurement,this paper analyzes and designs a dual-channel high-speed data acquisition and processing system for optical waveguide holographic response spectrum measurement.The main contents of this paper include:Firstly,the basic principle of interference spectroscopy is introduced,and the working principle of optical waveguide holographic response spectrum measurement system is described,and the requirements for data acquisition and processing in the measurement system are analyzed.Then,according to the requirements of the measurement system,the overall design scheme of the data acquisition and processing system with FPGA(Field Programmable Gate Array)as the main control chip is formulated.Two high-speed AD(Analog-to-Digital)chips are used to realize the independent dual-channel signal input.FPGA controls the AD chip for data acquisition,and then performs fast Fourier transform processing on the data inside the FPGA and caches the data in DDR(Double Data Rate)memory.Then the FPGA controls the USB(Universal Serial Bus)chip to transmit the data to the host computer program developed by Lab VIEW(Laboratory Virtual instrument Engineering Workbench)software for display and storage to the computer.Finally,the designed data acquisition and processing system is tested and analyzed,and the experimental results prove that the system design is reasonable and feasible.This subject provides technical support and lays an important foundation for further optimizing of holographic response spectrum measurement methods of optical waveguide devices.