US Patent 7258494 Optical module for multi-wavelength

An optical module includes a module body on which at least one photo diode is mounted, a filter holder inserted into the module body, and a thin film filter mounted on the filter holder in order to guide optical signals towards photo diodes in such a manner that optical signals with corresponding wavelengths are received in the photo diodes. The filter holder, on which the thin film filters are mounted, is fabricated separately from the module body and houses active elements, such as the laser diode and photo diodes. The filter holder is inserted into the module body thereafter, so the optical module is easily fabricated at a low cost and in a simple manner.