Parallel optical interconnection using self-adjusting microlenses on injection molded ferrules made by LIGA technique

Prototypes of compact lensed fiber connectors have been fabricated by LIGA technique that provide multimode connections for parallel optical interfaces. Contactless embossed microlens arrays were introduced as collimating and focusing elements in order to achieve a simplified connector assembly. As an alternative ball lenses were inserted in a second type of expanded-beam connector ferrule. Fibers, microlens arrays or respectively single microlenses, and two metal guiding pins an passively adjusted in high precision alignment structures. The ferrules are injection molded and the modular mold insert has been fabricated by means of microtechnology: LIGA technique and electro-discharge machining. Insertion loss values of 4.5 dB have been measured for assembled mated couples of females with contactless embossed microlens arrays and 2.3 dB for ferrules with ball lenses, both at @1310 nm including reflection losses of typical 1 dB. Even though commonly used butt-coupling connectors show lower insertion loss values, the introduced compact expanded-beam connectors could offer an attractive solution for applications in harsh or dirty environments or for micro-optical components e.g. compact 90 degrees optical interfaces for backplane connectors or switches by deflecting the expanded optical beam by a miners or prisms.