Abstract: An optical spectrum analyzer apparatus for analyzing the spectral content of a light signal. The optical spectrum analyzer apparatus includes an optical tapped delay line (OTDL) unit as a light dispersing unit to provide an analyzer apparatus having increased resolution.

Abstract: An optical position-tracking system comprises an optical device for generating an incident light beam and a reference light beam from a light beam. Moreover, the optical position-tracking system further comprises a light beam steering device for sweeping the incident light beam through an angular range to cause a reflection of the incident light beam by a target, whereas the reflection of the incident light beam is directed to interfere with the reference light beam to form an interference light beam. Additionally, the optical position-tracking system enables determination of a position of the target using an interferometric technique utilizing an angular value of the incident light beam and the interference light beam, whereas the angular value depends on the reflection.

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: An optical heterodyne detection system includes a tunable optical pre-selector that is adjusted to track the frequency of a swept local oscillator signal. The tunable optical pre-selector is adjusted in response to a measure of the frequency of the swept local oscillator signal and in response to a measure of a portion of the swept local oscillator signal after the portion of the swept local oscillator signal has optically interacted with the optical pre-selector. In an embodiment, at least some portion of the swept local oscillator signal is modulated before it interacts with the optical pre-selector. In an embodiment, the portion of the swept local oscillator signal that interacts with the pre-selector is detected and used in a feedback control circuit to generate a control signal which causes the error between the center frequency of the pre-selector and the frequency of the swept local oscillator signal to be small.

Abstract: A system for characterizing optical properties of a device under test (DUT) uses an expanded local oscillator signal to perform multiple parallel interferometric measurements. In one system, the expanded local oscillator signal is optically connected to a lens array. The lens array focuses the expanded swept local oscillator signal into multiple beams. The multiple beams are then used in multiple parallel interferometric measurements. The multiple beams may be used as the reference beams or applied to the DUT and used as the test beams depending on the application. The test beams and reference beams are combined to perform the interferometric measurements. In another system, a portion of the expanded local oscillator signal is applied directly to a DUT as the test beam while another portion of the expanded local oscillator signal is used for the reference beam.

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: 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 external cavity laser system includes an in-line optical filter and a reflection suppressor that efficiently suppresses back-reflected light while allowing light to resonate within the laser cavity. The reflection suppressor may include a polarizer that polarizes light within the cavity and polarization rotators that rotate the polarization state of the polarized light such that back-reflected light is suppressed by the polarizer. Because back-reflected light is suppressed, use of an in-line filter becomes viable in an external cavity laser system.

Abstract: Characterizing active and passive properties of an optical device involves applying a local oscillator signal to a device under test (DUT) and providing a portion of the local oscillator signal (referred to as the reference local oscillator signal) directly to the an optical analyzer. Providing the reference local oscillator signal to the optical analyzer enables interferometric measurements associated with the DUT to be obtained along with direct measurements, where the interferometric measurements result from combining the portion of the local oscillator signal that is applied to the DUT with the reference local oscillator signal. The interferometric measurements are used to characterize passive properties of the DUT while the direct measurements are used to characterize active properties of the DUT.

Abstract: Monitoring an optical signal utilizing optical heterodyne detection involves attenuating an input signal before the input signal is combined with a local oscillator signal. The input signal is attenuated in order improve the signal to noise ratio of the heterodyne signal that is generated when the input signal and the local oscillator signal are combined. The signal to noise ratio of the heterodyne signal improves with attenuation of the input signal, specifically in the case where the intensity noise from the input signal is the dominant noise source, because the heterodyne signal and the intensity noise of the input signal scale differently with attenuation of the input signal.

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: A heterodyne optical network analyzer and method for device characterization reduces the effect of relative intensity noise (RIN) in interferometric optical measurements by subtracting the measured intensities of first and second interference signals derived from an optical interferometer. The first and second interference signals are produced by combining a first lightwave transmitted to an optical device being characterized with a second lightwave, which is a delayed version of the first lightwave. The first and second lightwaves are derived by splitting an input lightwave having a continuously swept optical frequency generated by a light source, such as a continuously tunable laser.

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: 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: An optical spectrum analyzer apparatus for analyzing the spectral content of a light signal. The optical spectrum analyzer apparatus includes an optical tapped delay line (OTDL) unit as a light dispersing unit to provide an analyzer apparatus having increased resolution.

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 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.

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: An optical switch, preferably an add/drop switch, includes a minimal number of two-state switching arrangements, thereby facilitating a reduction of switch complexity. Light pulses entering the switch via a given input port may be directed to either a corresponding output port or a corresponding drop port by the operation of the switching arrangements. Light pulses entering the switch via a given add port may be directed to a corresponding output port or may be disbursed by the operation of the switching arrangements. The switching arrangements are toggled between reflective and transmissive states. In the preferred embodiment, the two-state switching arrangements are controlled by the manipulation of index matching fluid within trenches. Additionally, in the preferred embodiment, the switching arrangements are configured such that a given light pulse interacts with only one trench, thereby minimizing the overall signal loss and loss non-uniformities within the switch.

Abstract: A system for measuring optical characteristics of a multiport optical device uses optical heterodyne detection and known port-specific transmission delays to simultaneously monitor multiple ports of the multiport optical device with a single receiver. An embodiment of a system includes a splitter configured to split a swept optical signal into a reference signal and a test signal and a test system input, connectable to the multiport optical device, for transmitting the test signal to the multiport optical device. The test system also includes an optical combiner and a receiver. The optical combiner is connectable to the multiport optical device to receive a first portion of the test signal having a first port-specific transmission delay and to receive a second portion of the test signal having a second port-specific transmission delay.