Influence of analyzed signals fiber-optic transmission system on spread function of the diffraction grating spectral device

Abstract

Fiber-optic transmission system of analyzed signal is considered to allow signals transmission from optical sources with either impossible or undesirable contact. Diffraction grating spectral device is chosen as investigation system. It should be noted that diffraction grating operates with transmitted light but not reflected. Influence of optical fiber consists in the distortion of wave front incident on the spectral device. Front distortion leads to a broadening of the device spread function in all diffraction orders, and as a consequence, to a deterioration in the device resolution. In this case, the complex spread function is a reaction of the device to the homogeneous plane monochromatic wave which clearly links the input-output of spectral device. Fiber-optic system influence is determined by introducing a fictitious transparency located directly in front of the diffraction grating. Research of the effect the fiber-optic system has on the spread function of the diffraction grating spectral device is made in two ways. On one hand, mathematical model is proposed to describe the influence of a single-mode optical fiber to a spread function of the diffraction grating spectral device. We performed computer simulations of the analyzed signal transmission from the end of the optical fiber to the photodetector based on the proposed model. The calculations are performed for a single-mode optical fiber with a core diameter of 8 microns. On the other hand, experimental laboratory set up of the diffraction grating spectral device with a fiber optic transmission system is created. Theoretical calculations are compared with the experimental results.