Abstract: A fiber block for connecting optical fibers to an optical device comprises a lithographically defined front face and a plurality of recesses for optical fibers extending linearly from the front face in a plane which is substantially perpendicular to the front face, at an angle within that plane which is non-perpendicular to the front face. It is preferred that the block is essentially rectangular with recesses for the optical fiber formed in it in a non-perpendicular arrangement. The block is preferably formed as two mating parts each with aligned recesses on their mating faces, thereby to permit an optical fiber to be held in a pair of recesses one on each part. The recesses can end with a locally narrower portion which acts as an end stop for the fiber thereby to permit it to be located accurately. The recesses are preferably V-grooves and the block is preferably of silicon.