  EXPLANATION OF CATALOG TERMS ~OPTICAL DATA ANALYSIS RELATED~

EF（Encircled Flux）/EAF（Encircled Angular Flux） Both EF/EAF are used as an index for defining the excitation state of the multimode fiber. EF applies to GI fiber and EAF applies to SI fiber. ●EF (Encircled Flux) EF (Encircled Flux) is the ratio of the total near-field optical power to the total output optical power. It is expressed as a function of the radial distance r measured from the optical center of the optical fiber core and is defined by the following formula. ●EAF (Encircled Angular Flux) EAF (Encircled Angular Flux) is the ratio of the total far-field optical power to the total output optical power. It is expressed as a function of the angle θ′ between the optical center axis of the far field image and the emitted light, and is defined by the following formula. It is one of the definitions of beam diameter. When the circular area with radius r is set from the center of gravity position of the NFP beam profile, it represents the diameter (=2r) of the circle when 86.5% of the total power is included in the circular area. It can be obtained by calculating the value of r when the EF value is 86.5% from the EF measurement result. When the beam profile shape is Gaussian distribution, it has the same value as 1/e2 width. It is one of the definitions of beam diameter. It is calculated by finding the second moment (dispersion) from the luminance distribution of the NFP beam profile. The values of D4σ in the X direction and the Y direction are represented by the following formula. ●D4σ x ●D4σ y 