Abstract: A method for down-converting an RF signal is described that optically phase modulates an RF signal onto an optical carrier then applies an RF local oscillator (LO) phase modulation which down-converts the RF signal to an intermediate frequency after appropriate optical signal processing and optical-to-electrical photo-detection. The LO phase modulator is constructed such that a common hot electrode is shared among more than one optical mode, where an optical mode can be separate waveguides or optical wavelengths. The relative phase of the LO frequency applied to each optical mode can be different between the different optical modes. The resulting down-converted photo-detected signals of different LO-phase can be processed to reduce noise. A single LO phase modulator can down-convert multiple RF signals carried by multiple optical wavelengths, and a harmonic generation stage with multi-phase-matching peaks can be used to linearize each RF signal.

Abstract: Techniques to bolster the security of an AlphaEta cryptosystem using spectral phase encoding. In one aspect, a spatial light modulator (SLM) is used to change the spectral code (spectral phase) of each optical bit in response to the output of an extended key generator based on a cryptographic algorithm. In other aspects, additional time and polarization modulations are used to maintain high security levels as well as good performance levels. Such methods are combined with traditional key generation methods such as key-distribution centers or one-way mathematical algorithms to bolster the security of traditional key generation as well.