Compact wavelength multiplexer using optical-fiber pieces

The optical-wavelength-division multiplexer reported here is composed of three multimode fiber pieces with dielectric multilayers evaporated on the ends of the fibers, which have been polished obliquely or squarely. The working faces of these fibers are bonded together in a crossed V groove to duplex two wavelengths (λ = 0.82 and 1.2 µm). The far ends of the joined fiber pieces are left intact for splicing with fiber cables or are terminated with connector ferrules for connection. The multiplexer is small (1 cm square) and lightweight (1.5-3 g). It also shows low insertion loss (1 dB) and cross-talk level (below -40 dB). We have estimated that the cost of this type of component can be reduced to I order of magnitude lower than that of conventional lens and mirror types.