The SPIE Digital Library offers a comprehensive range of content on receivers, encompassing various aspects of their design, function, and application across multiple fields, particularly in optics and photonics. Optical receivers are a crucial component in optical communication systems, playing a vital role in detecting and processing optical signals. These systems convert electrical signals, which carry data, into pulses of light and then back into electrical signals at the destination. The optical transmitter and the optical receiver. Optical Detectors-PIN diode and APD diodes –Photo detector noise, SNR, –Comparison of Photo detectors – Fundamental Receiver Operation – Design of Analog Systems- Design of Digital Systems.