OPTICAL SIGNAL PROCESSOR

摘要

In a conventional optical signal processor, optical coupling loss occurring in a spatial optical system including a single lens is not reduced sufficiently. A lens of good performance is hard to manufacture and expensive. Furthermore, adjustment processing is complicated during manufacture of the optical signal processor and manufacturing cost is high. Crosstalk must be reduced by ensuring reflective attenuation in the optical system. While paying attention to reduction of TAS, an inventive lens arrangement is found using the refractivity (D1, D2, D3, D4) of each lens face as a parameter. In two groups of two lenses, focal distances of two lenses are close to each other (D1f+D2f~D3f+D4f~0.5), and wavelength dependent optical coupling loss is reduced sharply when a second condenser lens is a plano-convex lens (D3f~0.5) directing the convex side toward the first condenser lens.