INFRA-RED PHOTODETECTOR The BPW41D is a large area, silicon p.i.n. photodiode having a low junction capacitance and consequently capable of fast response times. Tha active chip is packaged in a plastic moulding which contains a near infrared transmissive filter such that the device is sensitive to infrared radiation only, and has a high rejection of wavelengths below 800 nm. The BPW41D is therefore eminently suitable for use in I.R. remote control links.