Agilent Technologies, Inc.

Keysight Technologies, Inc.

Ap Sensing Gmbh

Bernd Nebendahl

Emmerich Mueller

Wolf Steffens

Ulrich Kallmann

Marcel Zeiler

Ralf Haeussler

Jochen Schwarz

Thomas Jensen

Bogdan Szafraniec

Ruediger Maestle

Peter Thoma

Hansjoerg Haisch

Andreas Schmidt

Michael Schubert

Matthias Jaeger

Rudiger Maestle

J&ouml;rg Schmidt

Jochen Buhl

An apparatus for determining a wavelength and a power of an input signal is described. The apparatus comprises a memory which stores instructions, which when executed by the processor, cause the processor to: recover a first phase for a first Mach-Zehnder Interferometer MZI; recover a second phase for a second MZI; subtract the first phase from the second phase to provide a phase difference; determine an unwrapped phase difference as a function of wavelength; determine a coarse wavelength; and determine a first wavelength for the first FSR and a second wavelength from the second FSR; and average the first and second wavelengths to determine the wavelength of the input signal.

Optical wavemeter

An optical device having a wavelength measurement section and an SMRS measurement section is disclosed. The wavelength measurement section includes a MZI, which includes first optical waveguides having a first optical path length difference. The wavelength measurement section also includes a second MZI, which includes second optical waveguides having a second optical path length difference. The second optical path length difference is greater than the first optical path length difference. The SMRS includes a filter adapted to suppress a primary laser mode of the second output optical signal and to pass a remaining portion of the second output signal to determine an SMRS based on an optical power of the main laser mode from the wavelength and power measurement stage, and an optical power of the remaining portion of the second output optical signal.

A photonic integrated circuit (PIC) for determining a wavelength of an input signal is disclosed. The PIC comprises: a substrate; a first Mach-Zehnder Interferometer (MZI) disposed over the substrate, comprising first optical waveguides having a first optical path length difference, and configured to receive a first output optical signal from a light source. The PIC also comprises a second Mach-Zehnder Interferometer (MZI) disposed over the substrate, comprising second optical waveguides having a second optical path length difference, which is greater than the first optical path length difference, and configured to receive a second output optical signal from the light source.

An apparatus includes an optical splitter configured to receive an optical signal and to split the input optical signal to provide a first and a second optical signal. The apparatus further includes an interferometer comprising a first arm and a second arm, with the first arm being configured to receive the first optical signal, and the second arm being configured to receive the second optical signal. Notably a portion of the first arm is exposed to a reference gas that attenuates light of a characteristic wavelength. The apparatus further includes an optical coupler configured to receive an output optical signal from the first arm, and an output optical signal from the second arm and to provide a third optical signal; and a photodetector configured to receive the third optical signal, and to provide a photocurrent. The photocurrent increases when the difference between the characteristic wavelength and the wavelength of the optical signals increases. The apparatus also comprises a feedback control circuit configured to change the properties of the laser to be locked until an error signal indicative of the difference between the characteristic wavelength and the wavelength of the laser is substantially zero.

Laser wavelength center lock using photonic integrated circuit

A tunable filter device includes a wavelength dependent splitter; a tuning element that tunes a characteristic wavelength of the wavelength dependent splitter to a wavelength of an optical signal; and a first optical coupler that splits the optical signal into an input optical signal input to the wavelength dependent splitter and a reference optical signal, where a first output outputs a band stop filtered portion and a second output outputs a band pass filtered portion of the input optical signal. The device further includes a second optical coupler that combines the reference optical signal with the band stopped filtered portion to provide a coupled optical signal; a photodiode that provides at a photocurrent indicating a difference between the wavelength of the optical signal and the characteristic wavelength; and a control loop that provides a control signal for automatically tuning the characteristic wavelength based at least in part on the photocurrent.

Continuously tunable optical filter

A system for continuously phase tuning an optical signal includes one optical switch coupled to a phase modulator having a first waveguide with a first phase shifter and a second waveguide with a second phase shifter. The optical switch alternately switches between the first and second phase shifters to phase shift the optical signal, respectively. The continuously phase tuning system further includes a loop mirror that alternately receives the phase shifted optical signal from the first and second waveguides in accordance with the switching, via corresponding first and second mirror inputs, respectively, and reflects the phase shifted optical signal back to the same first or second mirror input at which the phase shifted optical signal was received. First and second phase values of the first and second phase shifters are determined such that overall phase change continues to accumulate substantially linearly.

Continuous phase tuning system with loop mirror

A method of processing an optical input signal comprises transmitting the optical input signal through first and second signal paths, mixing the optical input signal with first and second local oscillator (LO) signals in the respective first and second signal paths to produce first and second electrical signals corresponding to different portions of a frequency spectrum of the optical input signal, and combining the first and second electrical signals to produce a coherent time-domain output signal.

Optical bandwidth interleaving

An apparatus calibrates an optical downconverter configured to receive an optical input signal at a signal input and an optical reference signal at a reference input, and to provide at multiple output nodes characterizing signals for characterizing the optical input signal. The downconverter includes receivers having corresponding optical inputs and respectively providing the characterizing signals at the output nodes, and multiple optical signal paths connected between one of the signal and reference inputs and one of the optical inputs. The apparatus includes a signal analyzing unit coupled to the output nodes and configured to receive and analyze the characterizing signals, a first switch for selectively enabling the optical input signal, and a second switch for selectively enabling the reference signal. The signal analyzing unit is configured to derive correction values based on determined signals at the output nodes derived from selectively enabling at least one of the optical input signal and the reference signal, and to correct the characterizing signals with the derived correction values.

Calibrating an optical downconverter

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.

Methods and apparatus for recovering first and second transmitted optical waves from a polarization multiplexed optical wave

Detecting different spectral components of a response signal received from a device under test -DUT- in response to a stimulus signal, with a first splitter receiving the response signal and wavelength depending splitting from response signal a first partial signal and a second partial signal, a second splitter receiving the second partial signal and wavelength depending splitting there from a third partial signal, an optical detector, for receiving the first partial signal and the third partial signal and determining a corresponding optical power, and an optical shutter arranged to be moved to either let through to or block from the optical detector one of: the first partial signal and the third partial signal.

Detecting different spectral components of an optical signal by means of an optical shutter

A laser apparatus for providing a stabilized multi mode laser beam includes an external cavity for providing an optical path for generating a laser beam which is stimulated by a gain medium, where the external cavity has first spectral characteristics, and a mode-selecting filter positioned within the optical path and having second spectral characteristics. The first characteristics and the second characteristics are adjusted to each other, so that the laser beam has at least two selected modes.

External cavity laser with multiple stabilized modes

A wavelength tunable laser unit has a laser mode selection, and is adapted to provide a laser signal in accordance with one or more laser control parameters. For operating the laser unit, the laser signal is swept in a wavelength range, a laser operation signal indicative of the laser unit's operation during the sweep is received, and the laser operation signal is analyzed for detecting an indication of a mode hop occurred in the generated laser signals during the sweep. At least one correction value is determined based on the detected mode hop indication, and at least one of the one or more laser control parameters, applicable for a next wavelength sweep, is modified based on the determined at least one correction value.

Wavelength tunable laser source with parameter correction

An apparatus and to a method of monitoring an interferometer, comprising the steps of: coupling a first optical signal into the interferometer and into a wavelength reference element, detecting a first resulting interference signal being a result of interference of parts of the first optical signal in the interferometer, detecting a resulting reference signal of the wavelength reference element, the resulting reference signal being a result of interaction of the first optical signal with the wavelength reference element, and comparing the first resulting interference signal with the resulting reference signal to detect a drift of the interferometer, if any.

Method and apparatus for monitoring an interferometer

Determining a physical property of a device under test&#x2014;DUT&#x2014;includes receiving an optical scatter signal returning from the DUT in response to a probe signal launched into the DUT, wavelength dependent separating a first response signal and a second response signal from the scatter signal, determining a first power information of the first response signal and a second power information of the second response signal, time-adjusting the first power response and the second power response to each other in order to compensate a group velocity difference between the first response signal and the second response signal within the DUT, and determining the physical property on the base of the time-adjusted power responses.

Optical reflectometry analysis with a time-adjustment of partial responses

The present invention relates to a determination of a physical state of an optical device by measuring a response signal. At least two subsequent measurements are executed. Therefore, a first optical signal is transmitted to the optical device, wherein a first optical property of said first signal is varied according to a first function of the time. A second optical property of a first response signal returning from the optical device is measured over the time and a first result function of the second optical property of the first response signal over the first optical property of first optical signal is established. Further, a second optical signal is transmitted to the optical device, wherein the first optical property of said signal is varied according to a second function of the time that is different from the first function of time. The second optical property of the corresponding second response signal is measured and a second result function of the second optical property of the response signal over the first optical property of the transmitted optical signal is established. The physical state of the optical device is determined on the base of a combination of the first and second result functions.

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Ditzingen, Germany

Bernd Nebendahl