Delay domain multiplexing, differing from coherence multiplexing of digital data signals, may use orthogonal encoding to reduce cross-channel interference compared to traditional techniques. A plurality of photonic encoders may receive laser pulses from a laser pulse source, converting the pulses into n sets of orthogonal codes, such as Walsh codes, depending on the number of channels to be multiplexed. A passive apparatus may use orthogonal codes, creating them fast enough to function in an optical or photonic environment. The orthogonal codes may subsequently be modulated with n digital data signals before being multiplexed and demultiplexed in a delay domain or coherence multiplexing apparatus. At a receiver, the encoded signals are decoded and the original digital data signals are extracted therefrom.
A particular signal from a legacy photonic source may have a distribution of wavelengths in a particular signal that is excessively broad for modem, narrowband equipment. In order to provide a drop-in apparatus for integrating modem narrowband signal carrying and handling devices with legacy equipment as either sender or receiver, various implementations of a data stabilizer are provided. Data stabilizers may rely on information transfer mechanisms, signal directors, wavelength shifters, cross-gain modulation, cross-phase modulation, and four-wave mixers. Moreover, data stabilizers may be implemented directly as multiplexers, or integrated into systems using conventional multiplexers.
A polarization insensitive photonic information router that can use polarization sensitive switches is disclosed. A photonic input signal is polarization separated into two paths having mutually orthogonal fixed polarizations and complementary amplitude fluctuations in accordance with polarization fluctuations of the input signal. Duplicate-acting switches, one for each fixed polarization, produce switched, polarized signal pairs. These are connected so as to recombine energy from both polarization contributions in each of the switched outputs. Recombining can standardize output polarizations, or reproduce the input polarization fluctuations. Polarization stabilization can also be used before switching. Decoding packet data to operate the switch produces a polarization insensitive packet switching router.
Multi-domain, phase-compensated, differential-coherence detection of photonic signals for interferometric processes and devices may be manufactured holographically and developed in situ or with an automatic registration between holograms and photonic sources in a single frame. Photonic or electronic post processing may include outputs from a cycling or rotation between differently phased complementary outputs of constructive and destructive interference. A hyper-selective, direct-conversion, expanded-bandpass filter may rely on an expanded bandpass for ease of filtering, with no dead zones for zero beat frequency cases. A hyper-heterodyning, expanded bandpass system may also provide improved filtering and signal-to-noise ratios. An ultra-high-resolution, broadband spectrum analyzer may operate in multiple domains, including complex "fingerprints" of phase, frequency, and other parameters. The associated technologies of the invention may be used to produce extreme precision in multi-domain locking of sophisticated waveforms varying in several domains.
A method and apparatus for hyper-dense communications provides a photonic signal, such as an optical or radio frequency signal produced with substantially reduced sidebands. Signals may be filtered photonically, such as by a photonic transistor or photonic drop filter, to remove such frequency components. The resulting bandwidth of the photonic output signal is narrower in the photonic domain than the bandwidth of the information it carries in the original domain of the information. This hyper-dense signal is then transmitted and received. Such signals retain their reduced spectral distributions while in the photonic domain. Upon reception and conversion into electronic form, the full spectrum of the original information may be restored, including the sidebands, by passing the transmitted signal through a non-linear device.