Research On Two-dimensional Spectrum Detection Based On The Imperfect Virtually Imaged Phased Array

The virtually-imaged phased array(VIPA)is an element of large angular dispersion and high resolution.When coupled with diffraction grating,it can achieve 2D imaging,easily to deal with spectrum and have been widely used for optical filter,spectrometer,image processing,and other fields.Therefore,many researchers dedicated to improve its dispersion law and application in the past few decades.In previous studies,the VIPA has been treated as an ideal glass plate with two parallel surface and its imperfect state has not been analysis.Actually,parallelism and finish will affect the VIPA multiple reflection and interference of the optical path,affecting spectral resolution and the output power.And when the back surface reflectivity is 95%of the VIPA,light reflects back and forth between the two sides,so the substrate surface type,parallelism and finish required is extremely high,leading to the production difficulties,low yield,high cost and loss of 13dB.Therefore,it's a necessary to study the imperfect VIPA and to improve its defects.The basic principle and effects of plate defects on imperfect virtually imaged phased array are investigated in this paper.A 2-D disperser is established by a virtually imaged phased array and a diffraction grating.The simulation model is established by ZEMAX.In addition,an element named finite reflection virtue imaging array(FRVIA)by us is proposed and a modified jammed-array wideband sawtooth filter based on the FRVIA is proposed.The main contents are as follows:(1)The dispersion law and 2-D spectral imaging of the VIPA are studied theoretically.The key performance parameters and optical field distribution are analyzed by numerical simulation.In addition,similarities and differences among dispersion laws are compared,which lay theoretically foundations for the following research.(2)A ZEMAX simulation model is established based on the two-dimensional spectral imaging principle of the VIPA.The parallelism and surface roughness of the glass plate are changed to analyze the effects of plate defects.Plate parallelism will affect the spot size of the beam output,the wavelength of the maximum power and 3 dB bandwidth,while the surface roughness will lead to scattering and loss.The simulation results are validated by experiment.(3)Elaborated the VIPA faults,this paper proposes an element named finite reflection virtue imaging array(FRVIA).It can reduce the wastage of the output face by reducing the back face of the reflectivity.The light field distribution of the FRVIA is deduced,and the effect of parallelism and roughness of FRVIA is analyzed based on the ZEMAX software.When applied to JAWS filter,it can reduce loss of 6 dB,Without using a large area of the photoelectric detector,the detector has high response speed,low noise and low cost.