Single- And Double-Mode Light Generation in DFB Fiber Laser: Wavelength-Scale Electromagnetic Modelling by the Method of Single Expression

Distributed feedback (DFB) semiconductor and fiber lasers are widely used in different area of science, technology, medicine, etc. Single- and double-mode operation of fiber lasers is very advantageous for telecommunication, spectroscopy, sensors applications, microwave generation, etc. However, there is a lack of a wavelength-scale electromagnetic analysis of such fiber lasers at the single- and double-mode radiation. In the current work the results of correct wavelength-scale electromagnetic analysis of radiation of DFB fiber lasers operating in single- and double-mode are presented. For wavelength-scale analysis the non-traditional method of single expression is used. In accordance with the known information, single- and double-mode radiation from DFB fiber laser is observed at single π-phase-shift in the middle of permittivity sinusoidal modulation of an amplifying fiber and equally spaced two π-phase-shifts, correspondingly. Numerically obtained wavelength-scale distributions of electric field component and power flow density within the DFB amplifying fiber will be useful in designing single- and double-mode radiating DFB fiber lasers.