Abstract: An apparatus for providing a test signal from a device under test (DUT) to a measurement instrument is disclosed. The apparatus includes a probe head configured to receive an electrical signal from the DUT. The probe head includes an electro-optic modulator. The apparatus also includes a control box, which includes an optical source. The optical source is configured to provide an input optical signal to the electro-optic modulator, which is configured to provide an output optical signal based on the electrical signal from the DUT. The control box also includes an optical bias control circuit. Only a bias control signal is provided to the electro-optic modulator.

Abstract: A system is provided for emulating return optical pulses from at least one emulated target in response to a time of flight (TOF) lidar signal. The system includes an optical blocker configured to partially reflect or guide emitted optical pulses emitted by a TOF lidar sensor; a detector configured to detect the partially reflected or guided optical pulses, and to output corresponding electrical pulses; an electrical delay circuit configured to delay the electrical pulses to indicate distance to the at least one emulated target relative to the TOF lidar sensor; at least one laser configured to reemit return optical pulses in response to the delayed electrical pulses; a collimator configured to collimate the return optical pulses; and a diffuser configured to diffuse the collimated return optical pulses over a predetermined range of azimuthal angles toward the TOF lidar sensor.

Abstract: Systems and components for testing a light detection and ranging (LIDAR) device under test (DUT) are described. In one example, an ellipsoid is adapted to receive the LIDAR DUT at a first focal point, where light transmitted from the LIDAR DUT is incident on the second focal point. In another example a plurality of optical waveguides arranged in at least a portion of a circle, and the plurality of optical waveguides are adapted to receive light from the LIDAR DUT. In another example, a LIDAR distance simulator is adapted to receive an optical input, and includes optical switches that are selectively connected to one of a plurality of optical delay devices to an input of the one of a plurality of optical input channels. Illustrative delay elements may be realized through optical delay elements or a combination of optical and electrical delay elements.

Abstract: An apparatus for providing a test signal from a device under test (DUT) to a measurement instrument is disclosed. The apparatus includes a probe head configured to receive an electrical signal from the DUT. The probe head includes an electro-optic modulator. The apparatus also includes a control box, which includes an optical source. The optical source is configured to provide an input optical signal to the electro-optic modulator, which is configured to provide an output optical signal based on the electrical signal from the DUT. The control box also includes an optical bias control circuit. Only a bias control signal is provided to the electro-optic modulator.

Abstract: A system includes a test signal generator generating a test signal having a carrier and at least two sidebands, and provides the test signal to a device under test (DUT). A plurality of couplers sense an incident signal, a reflected signal, and a transmitted signal for the DUT at corresponding test ports of the test system when the test signal is supplied to the DUT. A signal processing apparatus: detects S-parameters for the DUT from the carrier present in each of the incident signal, reflected signal, and transmitted signal for the device under test; measures a dispersion for the DUT at each of the test ports from the two sidebands present in the incident signal, reflected signal, and transmitted signal for the device under test using the two frequencies; and combines the detected S-parameters and the measured dispersions to output enhanced measurements of the S-parameters and the dispersions.

Abstract: Optical synthesis of frequency-tracking signals employs square-law based frequency conversion of pairs of optical signals having a predetermined, relative frequency shift to provide output signals. An optically synthesized tracking signal source includes a square-law photodetector configured to provide a first output signal having a frequency equal to a frequency difference between a first optical signal pair. Another square-law photodetector is configured to provide a second output signal having a frequency equal to a frequency difference between a second optical signal pair that is a frequency-shifted version of the first pair. The signal source further includes an optical wavemeter configured to determine one or both of the first pair frequency difference and the second pair frequency difference. The first and second output signals are tracking signals having a frequency offset determined by a relative frequency shift between the first and second pairs of optical signals.

Abstract: Tracking frequency conversion employs optical modulation of an optical signal to convert a radio frequency (RF) signal into an intermediate frequency (IF) output signal. A tracking frequency converter includes an optical modulator configured to receive the RF signal and to modulate the optical signal according to the received RF signal. The tracking frequency converter further includes a first square-law photodetector configured to receive the modulated optical signal and another optical signal to convert the received RF signal into the IF output signal. One or both of the modulated optical signal and the other optical signal is a tunable optical signal.

Abstract: Optical synthesis of frequency-tracking signals employs square-law based frequency conversion of pairs of optical signals having a predetermined, relative frequency shift to provide output signals. An optically synthesized tracking signal source includes a square-law photodetector configured to provide a first output signal having a frequency equal to a frequency difference between a first optical signal pair. Another square-law photodetector is configured to provide a second output signal having a frequency equal to a frequency difference between a second optical signal pair that is a frequency-shifted version of the first pair. The signal source further includes an optical wavemeter configured to determine one or both of the first pair frequency difference and the second pair frequency difference. The first and second output signals are tracking signals having a frequency offset determined by a relative frequency shift between the first and second pairs of optical signals.

Abstract: Tracking frequency conversion employs optical modulation of an optical signal to convert a radio frequency (RF) signal into an intermediate frequency (IF) output signal. A tracking frequency converter includes an optical modulator configured to receive the RF signal and to modulate the optical signal according to the received RF signal. The tracking frequency converter further includes a first square-law photodetector configured to receive the modulated optical signal and another optical signal to convert the received RF signal into the IF output signal. One or both of the modulated optical signal and the other optical signal is a tunable optical signal.

Abstract: A system includes a test signal generator generating a test signal having a carrier and at least two sidebands, and provides the test signal to a device under test (DUT). A plurality of couplers sense an incident signal, a reflected signal, and a transmitted signal for the DUT at corresponding test ports of the test system when the test signal is supplied to the DUT. A signal processing apparatus: detects S-parameters for the DUT from the carrier present in each of the incident signal, reflected signal, and transmitted signal for the device under test; measures a dispersion for the DUT at each of the test ports from the two sidebands present in the incident signal, reflected signal, and transmitted signal for the device under test using the two frequencies; and combines the detected S-parameters and the measured dispersions to output enhanced measurements of the S-parameters and the dispersions.

Abstract: An optical spectrum analyzer and a method of spectrally analyzing an optical signal. The optical spectrum analyzer includes a wave shaper such as an optical modulator that shapes an optical signal, a dispersive element such as a dispersive fiber in which the shaped optical signal is dispersed, a detector that provides an output signal indicative of the dispersed shaped optical signal, and a signal processor that analyzes the output signal, for example by calculating a transform such as an inverse Fourier transform or a Fourier transform of the output signal, to provide a frequency spectrum of the optical signal.

Abstract: An optical receiver and a method of demodulating an optical signal. The method includes combining a received optical signal with a local oscillator signal to construct a complex signal indicative of an optical field of the modulated optical signal and processing the complex signal recursively under control of a Kalman filter that enforces a constraint. The receiver includes an optical hybrid that combines a received optical signal with a local oscillator signal, a detector that recovers components of a complex signal, a processor that receives these components, and instructions that cause the processor to process the components of the complex signal recursively under control of a Kalman filter that enforces a constraint to recover data.

Abstract: First and second transmitted optical waves having orthogonal polarization states are combined in a polarization multiplexed optical wave. At an optical receiver, an electrical field of the polarization multiplexed optical wave is measured. A plurality of polarization states of the polarization multiplexed optical wave is determined from the measured electrical field. From the plurality of polarization states, a transform that aligns the orthogonal polarization states of the first and second transmitted optical waves with respect to principal axes of the optical receiver is estimated. The first and second transmitted optical waves are recovered by applying the transform to one of i) the polarization multiplexed optical wave and ii) the measured electrical field of the polarization multiplexed optical wave.

Abstract: An optical receiver and a method of demodulating an optical signal. The method includes combining a received optical signal with a local oscillator signal to construct a complex signal indicative of an optical field of the modulated optical signal and processing the complex signal recursively under control of a Kalman filter that enforces a constraint. The receiver includes an optical hybrid that combines a received optical signal with a local oscillator signal, a detector that recovers components of a complex signal, a processor that receives these components, and instructions that cause the processor to process the components of the complex signal recursively under control of a Kalman filter that enforces a constraint to recover data.

Abstract: First and second transmitted optical waves having orthogonal polarization states are combined in a polarization multiplexed optical wave. At an optical receiver, an electrical field of the polarization multiplexed optical wave is measured. A plurality of polarization states of the polarization multiplexed optical wave is determined from the measured electrical field. From the plurality of polarization states, a transform that aligns the orthogonal polarization states of the first and second transmitted optical waves with respect to principal axes of the optical receiver is estimated. The first and second transmitted optical waves are recovered by applying the transform to one of i) the polarization multiplexed optical wave and ii) the measured electrical field of the polarization multiplexed optical wave.

Abstract: An optical spectrum analyzer and a method of spectrally analyzing an optical signal. The optical spectrum analyzer includes a wave shaper such as an optical modulator that shapes an optical signal, a dispersive element such as a dispersive fiber in which the shaped optical signal is dispersed, a detector that provides an output signal indicative of the dispersed shaped optical signal, and a signal processor that analyzes the output signal, for example by calculating a transform such as an inverse Fourier transform or a Fourier transform of the output signal, to provide a frequency spectrum of the optical signal.

Abstract: A polarization dependent loss measuring device and the method of using the same are disclosed. The device includes a light source, a sensor, and a controller. The light source generates a polarization modulated light signal, and is adapted to apply the polarization modulated light signal to a device under test. The sensor generates an electrical output signal representing an intensity of an output light signal leaving the device under test as a function of time. The controller measures an amplitude and phase of the electrical output signal at a first frequency and generates an output indicative of a polarization dependent loss in the device under test.

Abstract: In one embodiment, a polarimeter includes a modulated polarizer, a detector and a processing system. The modulated polarizer is modulated at a modulation frequency and is configured to transmit a portion of an optical signal based on its modulation. The detector is configured to generate a time-varying output signal related to a time-varying power of the transmitted portion of the optical signal. The processing system is configured to i) detect at least three frequency components of the time-varying output signal, and ii) determine the polarization state of the optical signal based on the at least three frequency components.

Abstract: A system and method for superheterodyne detection in accordance with the invention. The system comprises a first conversion unit for performing a first heterodyne operation on an optical input signal to generate an electrical IF signal. A second conversion unit is electrically or optically coupled to the first conversion unit. The second conversion unit performs a second heterodyne operation to generate an electrical output signal suitable for signal processing.

Abstract: A method for characterizing a device under test includes propagating multiple optical signals through the device under test and combining the multiple optical signals with a reference optical signal. The multiple optical signals are mixed with the reference optical signal and a relative perturbation between the multiple optical signals from the mixing of the multiple optical signals with the reference optical signal is determined. In another embodiment a modulated optical signal is provided from a local oscillator and the modulated optical signal is combined with the input optical signal. The modulated optical signal is mixed with the input signal to provide a mixed signal and at least one polarization-resolved parameter of the input optical signal is extracted from the mixed signal.