New Photodiode Eliminates Need For Separate Filter April 2000 Issue Published Date: April 01, 2000
Using a new technique that deposits a multilayer optical filter directly onto a photodiode, the Filtrode family of detection devices permit the broad spectral band of silicon photodiodes to be fine tuned into specific zones of operation, thereby allowing them to operate in the presence of severe background light conditions (e.g., sunlight). Previously, in many photo-detection applications a separate wavelength-selective filter had to be used with the photodiode in order to discriminate the signal of interest from background light. Filtrode devices change all that by integrating an optical coating directly onto the diode surface and by encapsulating the photodiode into a clear material that allows light to be transmitted through the final package. The resulting device is said to combine specific wavelengths of operation with high quantum efficiency, sharp cut-on/cut-off shapes of about 5%. In addition, the filter-on-diode Filtrodes can be designed as a single- or double-sided light entry photodiode.
