IEC 63267-2-1:20 24定义了一组用于50/125 μ m的增强型宏弯曲、渐变折射率多模光纤连接的指定条件，所述多模光纤连接被维持以满足随机配对的抛光物理接触(PC)光纤对中的衰减和回波损耗性能的要求。 基于横向光纤芯偏移、数值孔径(NA)失配和光纤芯直径(CD)变化，在850nm的操作波长下，使用符合IEC 61300-1的环绕通量(EF)发射条件来确定性能等级。 考虑到现有技术，光纤芯角偏移被认为是不重要的，并且被排除为衰减估计的因素。IEC 63267-1中定义了衰减和回波损耗性能等级。

IEC 63267-2-1:2024 defines a set of specified conditions for an enhanced macro bend of 50/125 μm, graded index multimode fibre optic connection that is maintained in order to satisfy the requirements of attenuation and return loss performance in a randomly mated pair of polished physically contacting (PC) fibres.
An encircled flux (EF) compliant launch condition in accordance with IEC 61300-1, at an operational wavelength of 850 nm, is used for determination of performance grades, based on lateral fibre core offset, numerical aperture (NA) mismatch, and fibre core diameter (CD) variation.
Fibre core angular offset is considered insignificant given the state-of-the-art and is excluded as a factor for attenuation estimation. Attenuation and return loss performance grades are defined in IEC 63267-1.