Abstract: A receiver and method for using the same to process optical signals is disclosed. The receiver includes an optical coupler and a polarization dependent beam splitter. The optical coupler combines an input signal and a local oscillator signal into a first combined signal. The optical coupler includes a polarization filter that operates on the local oscillator to provide a linearly polarized signal having a predetermined LO polarization direction.

Abstract: In one embodiment, a method determines the spectral content of an optical signal. Specifically, the optical signal and an optical local oscillator (LO) signal are provided to inputs of an optical hybrid (e.g., an N×N optical coupler where N is greater than two). The phase-diverse components from the optical hybrid are photodetected allowing for mixing of the optical signal and the optical local oscillator. Bandpass filtering is performed to eliminate or reduce relative intensity noise (RIN). The filtered signals are mixed with an electrical LO signal. A quadrature representation of a phase-diverse heterodyne signal is generated from signals from the mixing. The negative image and the positive image from the quadrature representation are separated. The spectral content of the optical signal is determined from the images.

Abstract: An optical heterodyne detection system includes an attenuator for attenuating an input signal before the input signal is combined with a local oscillator signal. An optimal attenuation level for the input signal, which improves the signal to noise ratio of the heterodyne beat signal, is determined by obtaining a base measurement of an output signal in response to the local oscillator signal and in the absence of the input signal, obtaining sample measurements of the output signal in response to the input signal as a function of different attenuation levels, and determining the optimal attenuation level as a function of the base measurement and the sample measurements. A minimum attenuation level for the input signal, which protects receiver photodetectors from being saturated or damaged, is determined by setting an initial attenuation level and gradually reducing the attenuation level until the voltage limit of the photodetectors is reached.

Abstract: A compact, broadband laser source is realized by using a rare earth dopant to define a laser gain spectrum and by using holographic imprinting techniques to form a wavelength selection element for selecting a particular wavelength from within the gain spectrum. Artificial broadening of the gain spectrum can be achieved by establishing varied (e.g., randomized) domains of space charge within a rare earth-doped laser gain medium. Compactness can be enhanced by fabricating the laser gain medium and wavelength selection elements within a single member, such as a photorefractive crystal substrate. Flexibility in the selection of a wavelength can be obtained by holographically imprinting multiple sets of wavelength selection elements.

Abstract: An integrated-optical device comprising a photorefractive, quadratically electro-optic substrate having at least one optical waveguide channel and at least two electrodes. The photorefractive nature of the substrate and the quadratically electro-optic properties of the substrate enable optical waveguides of variable transmission to be formed in the substrate by applying a differential voltage to the substrate as it is exposed to relatively high intensity light. During operation, when a differential voltage is applied, the refractive index of the exposed regions of the substrate is altered and the exposed regions constitute one or more optical waveguides that are light-guiding with a transmission efficiency based on the magnitude of the voltage differential.

Abstract: An optical heterodyne detection system includes an attenuator for attenuating an input signal before the input signal is combined with a local oscillator signal. An optimal attenuation level for the input signal, which improves the signal to noise ratio of the heterodyne beat signal, is determined by obtaining a base measurement of an output signal in response to the local oscillator signal and in the absence of the input signal, obtaining sample measurements of the output signal in response to the input signal as a function of different attenuation levels, and determining the optimal attenuation level as a function of the base measurement and the sample measurements. A minimum attenuation level for the input signal, which protects receiver photodetectors from being saturated or damaged, is determined by setting an initial attenuation level and gradually reducing the attenuation level until the voltage limit of the photodetectors is reached.

Abstract: A method for determining at least one optical property of an optical device comprises providing an optical input signal that includes first and second signal components that are modulated at first and second frequencies, respectively, and that have first and second polarization states, respectively. The optical input signal is passed to an optical device. An optical output signal from the optical device is separated into first and second output signals that have third and fourth polarization states, respectively. The first and second output signals are each compared with reference signals at the first and second frequencies to provide four phase shift and amplitude measurements that can be used to determine the at least one optical property of the optical device as a function of wavelength.

Abstract: An artificial neural network is utilized as a filter in an optical heterodyne balanced receiver system. Such an artificial neural network can be adapted or trained to correct for non-ideal behavior and imperfections in the optical heterodyne system.

Abstract: A method for determining at least one optical property of an optical device comprises providing an optical input signal that includes first and second signal components that are modulated at first and second frequencies, respectively, and that have first and second polarization states, respectively. The optical input signal is passed to an optical device. An optical output signal from the optical device is separated into first and second output signals that have third and fourth polarization states, respectively. The first and second output signals are each compared with reference signals at the first and second frequencies to provide four phase shift and amplitude measurements that can be used to determine the at least one optical property of the optical device as a function of wavelength.

Abstract: Neutral particles, such as atoms and molecules, transported along a path having at least one curved region are selectively conveyed or filtered according to each particle's velocity by generating an inhomogeneous magnetic field across a cross-section of the path. The neutral particles may be transported through a physical tube or simply through the region defined by the magnetic field. The path may have more than one curved region and may additionally have one or more straight regions. The magnetic field may be generated for example by homogeneously or inhomogeneously magnetized permanent magnets or by current carrying elements. The magnetic elements may additionally be used in conjunction with at least one piece of a high permeability magnetic material for focussing or containing the magnetic field.

Abstract: A compact, broadband laser source is realized by using a rare earth dopant to define a laser gain spectrum and by using holographic imprinting techniques to form a wavelength selection element for selecting a particular wavelength from within the gain spectrum. Artificial broadening of the gain spectrum can be achieved by establishing varied (e.g., randomized) domains of space charge within a rare earth-doped laser gain medium. Compactness can be enhanced by fabricating the laser gain medium and wavelength selection elements within a single member, such as a photo-refractive crystal substrate. Flexibility in the selection of a wavelength can be obtained by holographically imprinting multiple sets of wavelength selection elements.