Research On Excellently Performed Method For Measuring Response Spectra Of Optical Waveguides

Optical waveguide devices are widely used in sensing,optoelectronic integration,communication,medical diagnosis and other fields.The response spectra of an optical waveguide device include amplitude spectra and phase spectra,which can be used to analyze,design and reconstruct the optical waveguide device.The amplitude spectrum can be measured by the existing spectral analyzers.However the phase is very sensitive to the structure change and noise interference of optical waveguide devices,so it is relatively difficult to measure the phase spectrum.At present,the phase spectra are mainly measured by using RF modulation method,coherent interference method,pulse scanning method and other methods,possessing many disadvantages such as time comsuption,complex operation,high cost,and inaccuracy.In order to solve the above problems,a measurement method of low-coherence waveguide holographic spectra by our research group has been proposed.However,this method has many shortcomings,such as large measurement error,low wavelength resolution,and lack of universality of the measured object.Therefore,based on the theory of low coherence interference,the research of the high precision and multi-type optical waveguide response spectra measurement method,namely the research of the high performance optical waveguide response spectrum measurement method,is carried out.The main contents of this paper include:Firstly,the basic principle of Fourier transform spectroscopy is described,and the shortcomings of low coherent waveguide holographic spectra acquisition methods are analyzed.A high performance waveguide response spectra measurement method is proposed and its principle is described,and the methods to improve the response spectrum performance are introduced.Then,the experimental system composed of optical path system,motion control system,photoelectric receiving and data acquisition system is analyzed and established.The motion control system driven by Lab VIEW is used to match the optical path between the reference arm in the optical path system and the optical path connected with the reference arm of the optical waveguide device to generate interference optical signal.The interference signal is obtained after passing through the photoelectric balance detector to filter the DC component.When the motion control system works in a steady motion state,the electrical signals are sampled at high sampling rate at equal intervals,and then the response spectra of the optical waveguide device is calculated by Fourier transform of the sampled electrical signals.Finally,the feasibility of the high performance optical waveguide response spectra measurement method and its superiority over the previous low coherent dry optical waveguide holographic spectra measurement method are verified.The theoretical response spectrum of optical fiber Fabry-Perot cavity is simulated by multi-beam interference principle.The response spectrum of Fabry-Perot cavity is measured by the established high performance optical waveguide response spectra measurement system.The experimental results are in agreement with the theoretical results,which proves the feasibility of the proposed method.Compared with the measured results of the previous method,the measured results reduce the measurement error and improve the wavelength resolution,which proves the superiority of the proposed method.In addition,the superiority of this method is embodied in the previous method can't measure the chirp of fiber Bragg grating and fiber Bragg grating response spectra of experimental measurements,and by using transfer matrix method to simulation the response spectra of the two gratings theory,and the measured results are consistent with theoretical results,also proves the feasibility of this method.At the same time,the errors of the present method in the measurement are analyzed,which provides a reference and experimental basis for the further improvement and application of the optical waveguide response spectra measurement method.