Abstract:
Embodiments include a method and apparatus used for automatic bias stabilization of a DP IQM based on MZM for transmitting DP-QPSK optical data and/or DP-16QAM optical data. The apparatus simultaneously dithers DC-bias voltages of in-phase child, quadrature-phase child, and parent MZMs with three different dither patterns in time-domain which are mutually orthogonal to each other in the frequency-domain for X and Y polarization IQ modulators. Tap monitor photodiodes detect an interference term between these three dither patterns for each polarization. The interference term is sampled using an ADC in the time domain. The time-synchronous detection method may solve a set of three simultaneous linear partial differential equations with three unknowns to compute controlled DC-bias voltages to set on the respective MZM with a solution set which may iteratively converge to a unique solution, thereby biasing the child MZM in dual-polarization IQM to transmission minimum and parent MZM in quadrature transmission.
Abstract:
A stabilisation system for stabilising an output of a controllable light or laser source comprises a randomizer for randomizing light from the controllable light or laser source to generate a speckle pattern; a detector for detecting the speckle pattern to determine one or more properties of the light and/or changes in one or more properties of the light; and a controller for controlling the controllable light or laser source based on the determined one or more properties of the light and/or changes in one or more properties of the light.
Abstract:
An ellipsometry system and a detection unit thereof are capable of achieving miniaturization and price reduction associated therewith. The ellipsometry system includes the detection unit that: has an optical polarization element; separates an interference polarization beam obtained by causing the object-reflected polarization beam and reference reflected polarization beam to interfere with each other into a plurality of interference polarization beams on a wavelength basis; and detects the respective separated polarization components in each wavelength. The optical polarization element: has a birefringence characteristic including a first refractive index and a second refractive index; receives the separated interference polarization beams of the respective wavelengths in a wavelength order and in a parallel manner; separates the separated interference polarization beam of each wavelength, on a polarization component basis, while transmitting the same, and outputs the respective separated polarization components in each wavelength in the same direction but along different optical axes.
Abstract:
Die Erfindung betrifft eine Vorrichtung zur Messung der relativen Position zweier relativ zueinander entlang einer Achse oder um eine Drehachse (D) bewegbarer Objekte mit einem Sender (12), der unpolarisiertes Licht aussendet, mit einem Polarisator (20), und mit wenigstens einem Empfänger (16), der die durch den Polarisator (20) durchtretende Lichtintensität misst, um ein positionsabhängiges Signal zu erzeugen, wobei vor dem Empfänger (16) ein Polarisationsfilter angeordnet ist und wobei sich der Empfänger (16) und der Polarisator (20) in Abhängigkeit von der relativen Position der beiden Objekte relativ zueinander bewegen, wobei der Polarisator (20) wenigstens zwei verschiedene Polarisationsrichtungen aufweist und wobei der Polarisator (20) auf einer Fläche angeordnet ist, welche gekrümmt ausgebildet ist.
Abstract:
A method for designing the spatial partition of a filter module (125) used in an aperture-multiplexed imaging system. The filter module is spatially partitioned into filter cells, and the spatial partition is designed by considering data captured at the sensor in light of an application-specific performance metric.
Abstract:
A procedure for self-calibration of an optical polarimeter has been developed that eliminates the need for "known" input signals to be used. The self-calibration data is then taken by moving a polarization controller between several random and unknown states of polarization (SOPs) and recording the detector output values (D 0 , ..., D 3 ) for each state of polarization. These values are then used to create an "approximate" calibration matrix. In one exemplary embodiment, the SOP of the incoming signal is adjusted three times (by adjusting a separate polarization controller element, for example), creating a set of four detector output values for each of the four polarizations states of the incoming signal - an initial calibration matrix. The first row of this initial calibration matrix is then adjusted to fit the power measurements using a least squares fit. In the third and final step, the remaining elements of the calibration matrix are adjusted to a given constraint (for example, DOP=100% for all SOPs).