Spectral modification by line singularity in Fresnel diffraction from 1D phase step

In this work, we show when a coherent beam of light diffracts from a 1D phase step of specified height, phase singularity appears in the diffracted field. By changing the height of the step, singularities for different frequencies or wavelengths are formed which modify the spectrum of the incident beam differently. We have calculated the modifying factor and simulated the modified spectral profiles for different singularities at points in the neighborhoods of the singularities for two different sources used in the experimental studies. In the latter studies, using a monochromator, we have specified the spectral profiles at points in the neighborhoods of the singularities. The simulation and experimental results are in very good agreement. Further development of the work and its potential applications are also discussed.