Systems and methods for forming a coherent optical phased array laser source from a spatially combined array of output beams is accomplished without any external measurement devices or wavefront sensors. A master oscillator laser is split into a plurality of optical beam transport and amplifier channels to produce a plurality of optical output beams that are spatially combined in an array format. The spatial phase state of the plurality of output beams is measured at the output of a spatial combiner without use of an external measurement device or sensor. The phase of the plurality of optical output beams is controlled to compensate both for aberrations induced by the optical beam transport and amplifier paths to produce a coherent and spatially phased laser beam at the output of the laser source or to produce a phased laser beam with prescribed phase state on each output beam.

A frequency separator includes a plurality of filters to separate light having a plurality of optical pulses, each of the optical pulses having one of a plurality of frequencies, into a plurality of light components, each of the light components being to have one of a plurality of frequency bands corresponding to the plurality of frequencies, in which among the plurality of filters, a center frequency of a first frequency band of a first filter and a center frequency of a second frequency band, adjacent to the first frequency band, of a second filter are separated beyond a bandwidth of each of the first and second frequency bands.

An optical transmission system includes: a transmission unit configured to co-propagate a signal light in which data is modulated and an idler light having complex amplitude that is phase conjugate with the signal light via an optical transmission medium; at least one optical amplifier configured to perform a phase sensitive amplification operation through an action among the signal light, the idler light, and an excitation light in a nonlinear medium; and a reception unit configured to receive the signal light that has been amplified by the optical amplifier, coherently detect the signal light and the idler light individually, and conduct a diversity synthesis to demodulate the data.

An apparatus and method for wavelength conversion of a signal, for example, a dual-polarization signal, is disclosed. The apparatus implements a single-loop counter-propagating wavelength conversion scheme which provides both up-conversion and down-conversion of the signal within the same loop. Nonlinear wavelength conversion devices in the loop provide both up-conversion and down-conversion of the polarization components of the signal within the loop depending on whether the polarization component travels through the nonlinear conversion device in a clockwise or a counter-clockwise direction. The wavelength-converted signal is available to be extracted from the wavelength-conversion loop. An all-optical wavelength-division multiplexing transponder based on the wavelength-conversion scheme is also disclosed.

The present invention relates to an imaging system, including: a coherent light source delivering an object beam and a reference beam; a device of modulation of the object beam with a modulation signal; an image sensor arranged to receive an interference pattern resulting from a combination of the object beam and of the reference beam; and a demodulation device, the system being configured to, during a measurement phase: apply to the modulation signal a first pseudo-random sequence of jumps of a parameter selected among the phase, the frequency, and the amplitude; and simultaneously apply to the modulated portion of the object beam a second pseudo-random sequence of jumps of said parameter, wherein the first and second sequences of jumps of said parameter are non-correlated.

The present invention relates to an imaging system, including: a coherent light source delivering an object beam and a reference beam; a device of modulation of the object beam with a modulation signal; an image sensor arranged to receive an interference pattern resulting from a combination of the object beam and of the reference beam; and a demodulation device, the system being configured to, during a measurement phase: apply to the modulation signal a first pseudo-random sequence of jumps of a parameter selected among the phase, the frequency, and the amplitude; and simultaneously apply to the modulated portion of the object beam a second pseudo-random sequence of jumps of said parameter, wherein the first and second sequences of jumps of said parameter are non-correlated.

The present invention provides an optical phase synchronization method characterized by involving applying a small phase modulation signal (dither signal) to local oscillator light, acquiring an error signal that is dependent on a phase shift, and controlling the phase shift. The present invention further provides an optical phase synchronization method characterized by involving inducing a specific phase pattern in dummy pulses in an optical resonator using injection light, applying phase modulation to the local oscillator light, and thereby acquiring a part of the measurement result of the dummy pulses as the error signal. The present invention is further characterized by arranging calculation pulses and phase synchronization dummy pulses in a distributed manner (for example, alternately) and increasing a pulse width using a narrow band electrical filter.

The present invention provides an optical phase synchronization method characterized by involving applying a small phase modulation signal (dither signal) to local oscillator light, acquiring an error signal that is dependent on a phase shift, and controlling the phase shift. The present invention further provides an optical phase synchronization method characterized by involving inducing a specific phase pattern in dummy pulses in an optical resonator using injection light, applying phase modulation to the local oscillator light, and thereby acquiring a part of the measurement result of the dummy pulses as the error signal. The present invention is further characterized by arranging calculation pulses and phase synchronization dummy pulses in a distributed manner (for example, alternately) and increasing a pulse width using a narrow band electrical filter.

A wavelength converter that converts signal light and pump light into a light containing a new wavelength component using a nonlinear optical fiber, has a PBS for splitting incident light into a first polarized wave and a second polarized wave, a first polarization controller provided between the PBS and a first end of the nonlinear optical fiber, and a second polarization controller provided between the PBS and a second end of the nonlinear optical fiber, wherein in an optical loop connecting the PBS, the first polarization controller, the nonlinear optical fiber and the second polarization controller, the first polarized wave and a first component of the pump light travel through the nonlinear optical fiber in a first direction, and the second polarized wave and a second component of the pump light travel through the nonlinear optical fiber in a second direction opposite to the first direction.

A method for demultiplexing and demodulating (in particular, “locally” demultiplexing and demodulating) amplitude-modulated signals grouped by means of orbital angular momentum multiplexing is described. The method involves demultiplexing and demodulating information a(t), b(t) modulated on each of a first modulated beam Fm1 and at least one second modulated beam Fm2, based on phase difference values ΔP.sub.ab and ΔR detected by beam detectors located downstream of an interferometric structure 40 to which two portions of the electromagnetic beam carrying the modulated channels are provided as inputs, multiplexed in the orbital angular momentum variable. There is also described a corresponding system 100 for demultiplexing and demodulating amplitude-modulated signals capable of implementing the aforesaid method.