Patent ID: 8340522

Claim:
A filter assembly for combining a wavelength multiplexed optical signal by multiplexing optical signals of different wavelength emitted from respective optical devices, and/or for dividing a wavelength multiplexed optical signal into optical signals of different wavelength and causing the optical signals of different wavelength to enter respective optical devices, wherein the filter assembly comprises: a light transmitting member within which each optical signal propagates; a lower reflective layer provided on a lower face of the light transmitting member and being in contact with the lower face, the lower reflective layer being formed over an entire surface of the lower face; upper reflective layers respectively being provided on and in contact with an upper face of the light transmitting member, the upper reflective layers being formed by masking regions corresponding to filter mounting portions provided at a predetermined pitch; and a plurality of glass blocks of a parallelepiped shape each of which having an optical filter, each of the plurality of the optical filters being formed on each of the entire face of each of the plurality of the glass blocks, each of a plurality of optical filters on the glass block facing the upper face of the light transmitting member and being disposed on and in a contact with the upper face of the light transmitting member by bonding with adhesive so as to cover the respective filter mounting portions, and wherein: each optical signal passes through only one of the plurality of optical filters and is reflected by the other of the plurality of optical filters; between adjacent ones of the plurality of optical filters, the each optical signal experiences multiple reflections by the lower reflective layer and the upper reflective layer; and the wavelength multiplexed optical signal propagates along the same optical path within the tight transmitting member, wherein the filter assembly further comprising: a plurality of glass blocks each of which having one of said upper reflective layers on lower face thereof facing the upper face of the light transmitting member; and a protective optical glass provided on tops of the plurality of glass blocks having the optical filter and the plurality of glass blocks having the upper reflective layer.