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We report the fabrication of a completely packaged (including electronic drivers) strictly nonblocking transparent optical 8 x 8 matrix switch for routing applications at wavelength 1.55pm. The matrix is realized in a hybrid way from eight identical submodules each containing a single InPDnGaAsP chip with two 1 x 8 switches in parallel. The average values for fiber-matrix-fiber insertion loss and cross talk suppression are 20 and 28 dB, respectively. The usable wavelength range is 1450-1600 nm. The results indicate that large InPEnGaAsP switching matrices may be realized. I[. INTRODUCTIONRANSPARENT optical matrix switches are essential T components to ensure a flexible and secure operation of complex filler based communication systems. The key requirements folr these switching devices are low insertion loss, high cross talk suppression, wide usable wavelength range, good output homogen'eity, low polarization dependence, low power consumption, imechanical and thermal stability, and short switching times.In recent yeius, some promising solid state switches have been presented in a variety of material systems, like lithium niobate [1] and [2], silica on silicon [3], polymer [4], and 111-V semiconductors [5]-[71.Especially in 111-V semiconductors, however, the dimensions of the presented matrices were usually limited to some small numbers (typically, M x N with both M and N smaller or equal than 4l.) by two major reasons.On the one hand, the still existing imperfections in the fabrication processes in conjunction with the requirement of achieving an acceptabsle yield were found to be compatible only with rather small monolithically realized matrices. On the other hand, the approach of assembling larger switching matrices in a hybrid way from smaller monolithic subunits, which are interconnected by some sort of fiber network was ruled out by an only poorly developed multifiber-chip coupling technology.Meanwhile, however, considerable progress has been made both in the fabrication technology of semiconductor switching devices allowing larger monolithic subunits and also in multifiber packaging technology [SI and [9] paving the way to a hybrid assembly of large matrices.In this paper, we point out how the achievements in these two fields can profitably be combined to fabricate large 111-V