Broadband measurements of chromatic dispersion of higher-order fiber modes selectively excited using a spatial light modulator

We report a white-light interferometric method for broad-band measurements of chromatic dispersion of higher-order-modes (HOMs) selectively excited in an optical fiber using a spatial light modulator (SLM). To excite a specific mode we appropriately modulated a phase distribution across a supercontinuum input beam with the SLM used in reflective configuration. For this purpose, the SLM surface was divided into azimuthally and radially distributed sectors which introduce the phase shifts equal alternately to 0 or π radians, similarly as in the targeted mode. The voltage applied to respective sectors of the SLM was corrected versus wavelength to ensure broad-band dispersion measurements for the required mode. For a given voltage setting, the dispersion measurements were possible without any correction over 250 nm in the visible and over even greater range in the infrared. We demonstrate feasibility of the proposed approach in the measurements of chromatic dispersion for all modes supported by Corning SMF-28e, i.e., LP01, LP11, LP21, LP02, and LP31. The measurements were conducted in the spectral range from 450 nm up to the cut-off wavelengths of respective higher order modes and up to 1600 nm for the fundamental mode.