Abstract: A test structure supports simultaneous characterization of a two port optical component. The test structure includes an input port for receiving an input signal from an optical source, two test ports for connecting the test structure to a component under test, separate optical paths for supplying reflected and transmitted optical response signals from the component under test to separate receivers, and optical components for combining a first portion of the input signal with the reflected optical response signal before the first portion of the input signal and the reflected optical response signal are detected by a first receiver and for combining a second portion of the input signal with the optical response signal before the second signal and the optical response signal are detected by a second receiver. The optical component of the test structure may be connected by optical fibers or integrated into a single substrate.

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 tunable optical cavity constructed from a fixed mirror and a movable mirror. The fixed mirror is attached to a substrate having a first electrically conducting surface. A support member having the moveable mirror supported thereon and having a second electrically conducting surface, is suspended above the substrate. A circuit applies an electrical potential between the first and second electrically conducting surfaces thereby adjusting the distance between the fixed and movable mirrors. The fixed mirror and the moveable mirror are positioned such that the mirrors form the opposite ends of the optical cavity. The distance between the fixed mirror and the moveable mirror is a function of the applied electrical potential. The support member has physical dimensions that are chosen such that the amplitude of thermally induced vibrations in the support member are less than 0.01 percent of the wavelength of the resonating light.

Abstract: Methods and systems allow an in situ determination of the magnitude of PMD in an optical network and provide an estimate of the PMD impairment in the transmitted signal even when PMD is time dependent.

Abstract: Method and system are disclosed for de-embedding optical component characteristics from optical device measurements In particular, the invention uses frequency domain averaging of the RBS on both sides of an optical component to determine one or more of its optical characteristics. Where the RBS has a slope (e.g., as in the case of a lossy fiber), a frequency domain least square fit can be used to determine the optical component characteristics. In addition, the invention uses a reference DUT to correct for variations in the frequency response of the photoreceiver A reference interferometer is used in the invention to correct for sweep non-linearity of the TLS. The optical component characteristics are then de-embedded from optical device measurements to provide a more precise analysis of the optical device.

Abstract: Heterodyne based optical spectrum analysis (OSA) involves mixing an input signal with a swept local oscillator signal to generate a heterodyne beat signal and then stretching the heterodyne beat signal before the signal is sampled. A system for optical spectrum analysis includes a local oscillator source, an optical coupler, a heterodyne receiver, and a processor. A circuit for stretching the heterodyne beat signal is included in the heterodyne receiver and may include a diode in series with a capacitor and a resistor or a diode in series with a capacitor and a switch. Stretching the heterodyne beat signal involves extending the duration of the signal so that the signal can be detected with fewer samples per unit of time than an unstretched signal. Another embodiment of an OSA includes a first data acquisition unit for obtaining low resolution data and a second data acquisition unit for obtaining high resolution data.

Abstract: An external cavity laser having a set atmosphere is disclosed. In an embodiment, the laser system includes a gain medium to emit light in response to an applied current, a wavelength selective reflector configured to resonate the light that is emitted from the gain medium, and a chamber containing a set atmosphere, the chamber being optically connected to the gain medium and the wavelength selective reflector such that the light that is emitted from the gain medium passes through the chamber.

Abstract: By making combined interferometric and polarimetric measurements on a device under test, the relative phase uncertainty in device characterizations performed with a polarimeter or polarization analyzer alone is removed. This allows determination of the group delay to within a constant offset and the chromatic dispersion of the device under test.

Abstract: An optical heterodyne detection system in accordance with an embodiment of the invention includes two optical receivers for separately measuring the power of an input signal and a local oscillator signal before the signals are combined. The measurements of the input signal and the local oscillator signal are then utilized to enhance the heterodyne signal to noise ratio by removing the intensity noise contributed by the input signal and the local oscillator signal. By measuring portions of the input signal power and the local oscillator signal power and then subtracting out the scaled quantities from the photocurrent measurement during signal processing, the signal to noise of the heterodyne signal is improved beyond that which is accomplished by known balanced receivers.

Abstract: In the measurements of optical characteristics, such as measurements of group delay using an interferometric system, vibration noise can be at least partially offset by providing corrections on the basis of detecting light patterns that are indicative of the vibration noise. In each embodiment, light beams propagating through first and second paths are combined to form an interference signal, which is analyzed to provide the basis for the adjustments.

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.

Abstract: An extended wavelength range light source for an optical instrument includes wavelength-tunable optical sources that generate optical signals, each of the optical sources having a distinct wavelength-tunable range which differs from the wavelength-tunable ranges of the other optical sources. A switch connected to each of the optical sources is configured to select any one of the optical sources.

Abstract: An optical interface device for use in coherent testing of a device for its response to a stimulus signal. The interface includes a reference signal generator for generating a reference signal and a stimulus signal from the light signal input to the interface. A first optical switch routes the stimulus signal to one of the device test ports. A second optical switch routes a light signal from the device under test to the test signal output port. A plurality of optical routers are utilized for connecting the device test ports to the first and second switches. The output of the optical routers also provides a signal related to the intensity of the light signal leaving the device test port for use in correcting the data for variations in intensity in the stimulus light signal. A polarization synthesizer for setting the polarization state of the stimulus signal may also be included.

Abstract: A light source for generating and coupling light from a first wavelength into an optical fiber. The light source includes an output laser having a first optical cavity that includes a bottom mirror located outside of the optical fiber, and a top mirror that includes a reflector located within the optical fiber. An active region between the top and bottom mirrors generates light of the first wavelength, preferably through optical pumping at a second wavelength. The reflector is preferably a Bragg reflector and may include a mechanism for altering the wavelength of the light reflected thereby as well as the distance between the top and bottom mirrors. The pumping light is preferably generated by a pumping laser that includes a second electrically pumped optical cavity having a top mirror that is electrically connected to the bottom mirror of the first optical cavity.

Abstract: A test structure supports simultaneous characterization of a two port optical component. The test structure includes an input port for receiving an input signal from an optical source, two test ports for connecting the test structure to a component under test, separate optical paths for supplying reflected and transmitted optical response signals from the component under test to separate receivers, and optical components for combining a first portion of the input signal with the reflected optical response signal before the first portion of the input signal and the reflected optical response signal are detected by a first receiver and for combining a second portion of the input signal with the optical response signal before the second signal and the optical response signal are detected by a second receiver. The optical component of the test structure may be connected by optical fibers or integrated into a single substrate.

Abstract: A method and an apparatus for determination of properties, e.g. of elements of the Jones matrix of an optical device under test, comprising the steps of: producing an incoming light beam, splitting the light beam into a first light beam and a second light beam, coupling the first light beam, preferably having two parts delayed with respect to each other, with a given initial polarization into the optical device under test, letting the second light beam travel a different path than the first light beam, superimposing the first light beam and the second light beam to produce interference between the first light beam and the second light beam in a resulting superimposed light beam, splitting the superimposed light beam into a third light beam polarization dependent and a fourth light beam, detecting the power of the third and the fourth light beam as a function of frequency when tuning the frequency of the incoming light beam over a given frequency range, deriving optical properties, e.g.

Abstract: Heterodyne-based optical spectrum analysis involves measuring the sweep rate of a swept local oscillator signal and then generating an output signal that accounts for non-uniformities in the sweep rate of the swept local oscillator signal. In an embodiment, an input signal is combined with a swept local oscillator signal in an optical coupler and the sweep rate of the swept local oscillator signal is measured in a relative frequency measurement system. The combined optical signal is output from the optical coupler to a receiver and a heterodyne beat signal is generated. The heterodyne beat signal and measured local oscillator frequency sweep rate information are utilized by a signal processor to generate an output signal that is indicative of an optical parameter of the input signal and that accounts for non-uniformities in the sweep rate of the local oscillator signal.

Abstract: A tunable optical filter utilizes multiple electroholographic (EH) gratings with different center wavelengths to filter an optical signal over a wide wavelength range. The EH gratings are connected such that an input optical signal passes through at least one of the EH gratings. The EH gratings are activated and tuned by electrode pairs that are controlled through a voltage controller. The tunable optical filter is coarse tuned by activating the EH gratings having a wavelength range that includes the center wavelength that is to be filtered and fine tuned by adjusting the voltage that is applied across the activated EH gratings.