Abstract: An optical signal repeater where an upstream modulator is configured to generate an optical upstream output signal by modulating an optical carrier signal, and to transmit the optical upstream output signal to an upstream fibre-optic output port. A downstream modulator is also configured to generate an optical downstream output signal by modulating an optical carrier signal and to transmit the optical downstream output signal to a downstream fibre-optic output port. By ensuring that the wavelengths of the optical carrier signals are equal or substantially equal, the wavelength drift in the upstream direction can be kept equal to the drift in the downstream direction. These repeaters can be used for time and frequency synchronization in long-distance fibre-optic networks.

Abstract: A generator device for generating an arbitrary optical pulse pattern includes: a light source to provide primary laser pulses, a distributor to provide a plurality of primary optical pulses by distributing light of the primary laser pulses (LB00k) into a plurality of branches, a combiner to form an output signal by combining modulated optical signals from the branches, and a controller unit to provide control signals for controlling optical modulators of the branches, wherein a first branch comprises a first optical modulator to form a first modulated optical signal from primary optical pulses of the first branch, wherein a second branch comprises a second optical modulator to form a second modulated optical signal from primary optical pulses of the second branch, and wherein a propagation delay of the second branch is different from a propagation delay of the first branch.

Abstract: A system for providing stealthy vision, includes a source element providing electromagnetic radiation at a predetermined wavelength to illuminate a target; and a camera imaging the target to be illuminated; wherein the source element provides electromagnetic radiation including shortwave infrared light; and wherein the predetermined wavelength includes a wavelength in the near infrared spectrum wherein the absorption features of an atom or a molecule present in the medium where the electromagnetic radiation propagates form a continuum, that is a wavelength region wherein two or more narrow absorption lines are close enough to each other that they effectively form a single absorption area with a width greater than that of a single absorption line so that the range of the electromagnetic radiation in the medium is limited for all wavelengths within the continuum; wherein the region corresponds to a wavelength range centered at about 1382.8 nm, 1388.1 nm or 1392.4 nm.

Abstract: A generator device for generating an arbitrary optical pulse pattern includes: a light source to provide primary laser pulses, a distributor to provide a plurality of primary optical pulses by distributing light of the primary laser pulses (LB00k) into a plurality of branches, a combiner to form an output signal by combining modulated optical signals from the branches, and a controller unit to provide control signals for controlling optical modulators of the branches, wherein a first branch comprises a first optical modulator to form a first modulated optical signal from primary optical pulses of the first branch, wherein a second branch comprises a second optical modulator to form a second modulated optical signal from primary optical pulses of the second branch, and wherein a propagation delay of the second branch is different from a propagation delay of the first branch.

Abstract: A system for providing stealthy vision, includes a source element providing electromagnetic radiation at a predetermined wavelength to illuminate a target; and a camera imaging the target to be illuminated; wherein the source element provides electromagnetic radiation including shortwave infrared light; and wherein the predetermined wavelength includes a wavelength in the near infrared spectrum wherein the absorption features of an atom or a molecule present in the medium where the electromagnetic radiation propagates form a continuum, that is a wavelength region wherein two or more narrow absorption lines are close enough to each other that they effectively form a single absorption area with a width greater than that of a single absorption line so that the range of the electromagnetic radiation in the medium is limited for all wavelengths within the continuum; wherein the region corresponds to a wavelength range centered at about 1382.8 nm, 1388.1 nm or 1392.4 nm.

Abstract: In an aspect, an apparatus for distribution of frequency reference to a receiving end over a transmission medium comprises a first mixer adapted to mix a frequency reference signal having a reference frequency with a local oscillator signal having a local oscillator frequency to provide a forward frequency reference signal, a communication section adapted to transmit the forward frequency reference signal and receive a first backward frequency reference signal, a second mixer adapted to mix the first backward frequency reference signal with the local oscillator signal to provide a second backward frequency reference signal and a phase comparator and control circuit adapted to adjust the local oscillator frequency based on a phase shift of the second backward frequency reference signal so as to compensate for a phase shift of the forward frequency reference signal.

Abstract: A limited range source of electromagnetic radiation and a radiation method, includes a tunable source of electromagnetic radiation; and a control element configured to tune the wavelength of the source of electromagnetic radiation to a desired wavelength corresponding to an absorption line of an atom or a molecule or other species present in the medium through which the electromagnetic radiation is to propagate; wherein the control element is configured to receive data relating to the desired wavelength.

Abstract: A limited range source of electromagnetic radiation and a radiation method, includes a tunable source of electromagnetic radiation; and a control element configured to tune the wavelength of the source of electromagnetic radiation to a desired wavelength corresponding to an absorption line of an atom or a molecule or other species present in the medium through which the electromagnetic radiation is to propagate; wherein the control element is configured to receive data relating to the desired wavelength.

Abstract: In an aspect, an apparatus for distribution of frequency reference to a receiving end over a transmission medium comprises a first mixer adapted to mix a frequency reference signal having a reference frequency with a local oscillator signal having a local oscillator frequency to provide a forward frequency reference signal, a communication section adapted to transmit the forward frequency reference signal and receive a first backward frequency reference signal, a second mixer adapted to mix the first backward frequency reference signal with the local oscillator signal to provide a second backward frequency reference signal and a phase comparator and control circuit adapted to adjust the local oscillator frequency based on a phase shift of the second backward frequency reference signal so as to compensate for a phase shift of the forward frequency reference signal.