Abstract: A linear phase demodulator/down-converter comprises an optical amplitude modulator for modulating the amplitude of an optical input signal, a photo-detector, a loop filter and an optical phase modulator provided with a light source. The optical phase modulator/down-converter provides optical down conversion, optical up conversion, or a combination thereof. The photo-detector can be a balanced photo-detector. Linear phase demodulation and/or down conversion is performed completely in the optical domain.

Abstract: Disclosed is a Photonic Phase Locked Loop (PPLL) detector/discriminator, which makes possible a system for optically transmitting electromagnetic signals through a transmission medium (such as optical fiber, optical waveguide, underwater, in biological tissue, or in free space) with high sensitivity and extremely high dynamic range exceeding what is possible with present optical intensity modulated (AM) systems. Information is encoded on an optical carrier through the use of phase modulation (PM) or frequency modulation (FM). This information is subsequently demodulated into an accessible form through the use of the PPLL.