BS EN 61755-3-31:2015

What is BS EN 61755-3-31- Connector optical interfaces about? 

BS EN 61755-3-31 is a safety standard on the connection parameters of non-dispersion shifted single-mode physically contacting fibres. 

BS EN 61755-3-31 defines certain dimensional limits of an angled PC rectangular polyphenylene sulphide (PPS) ferrule optical interface to meet specific requirements for fibre-to-fibre interconnection. Ferrules made from the material specified in BS EN 61755-3-31 are suitable for use in categories C, U, E, and O as defined in IEC 61753-1. 

Note: Ferrule interface dimensions and features are contained in the IEC 61754 series, which deals with fibre optic connector interfaces. 

Who is BS EN 61755-3-31- Connector optical interfaces for?  

BS EN 61755-3-31 on the connection parameters of non-dispersion shifted single-mode physically contacting fibres is relevant to: 

• Manufacturers of fibre optic interconnecting devices and passive components 
• Manufacturers of connector optical interfaces  
• Manufacturers of ferrules 
• Manufacturers of optical fibre  
• Fibre optic technicians 
• Fibre optic workers 
• Testing authorities 

Why should you use BS EN 61755-3-31- Connector optical interfaces? 

The performance of a single-mode angled PC rectangular ferrule optical interface is determined by the accuracy with which the optical datum targets of two mating ferrules are aligned with each other. 

There are three conditions affecting the alignment of the optical datum targets, which are:  

• Lateral offset 
• Angular offset 
• Longitudinal offset 

Parameters influencing the lateral and angular offset of the optical fibre axes include the following: 

• Fibre hole deviation from a designated location 
• Fibre cladding diameter relative to fibre hole clearance 
• Fibre hole angular misalignment 
• Fibre core concentricity relative to the cladding diameter 
• Alignment pin diameter relative to the guide hole clearance 

Parameters influencing the longitudinal offset of the optical fibre axes include the following: 

• Fibre protrusion 
• Fibre array minus coplanarity 
• Adjacent fibre height differential 
• End face angle in the x-axis 
• End face angle in the y-axis 
• End face radius in the x-axis 
• End face radius in the y-axis 
• Fibre tip spherical radii 
• Axial force on the ferrule end face 
• Ferrule and fibre material constants 
• Frictional force of alignment pins in ferrule guide holes 

BS EN 61755-3-31 defines the dimensional limits of angled PC rectangular ferrules with a single row of up to 12 fibres. The fibre centres are spaced with a nominal alignment pitch of 0,25 mm. 

Interface variants, which identify nominal ferrule cross-sections and applicable fibre counts are addressed in BS EN 61755-3-31. BS EN 61755-3-31 also defines optical interface dimensions related to a lateral and angular offset and the alignment pin geometry. The end face geometry parameters that influence longitudinal offset are outlined in BS EN 61755-3-31. 

Overall, BS EN 61755-3-31 is useful as it provides guidance on the rectangular ferrule connector core alignment specifications that are defined at the single-channel level. BS EN 61755-3-31 provides optical fibre-to-fibre interconnection, mating ferrules.