Measurement Of Polarization State Research Articles

Real-time measurement of pump beam polarization through the transmitted light intensity in a polarized alkali metal vapor cell

A laser beam with left-/right-handed circular polarization is generally used to create the oriented atomic spins for precision measurements in a spin-exchange relaxation-free (SERF) co-magnetometer. The fluctuation of laser polarization interferes with the spin polarization of alkali metal atoms, leading to the system performance degradation. Here, we report a method for real-time polarization state measurement by using the transmitted light intensity of the pump beam passing through the vapor cell. Based on the principle of circular dichroism, the optical absorption model of polarized alkali metal atoms is established. The simulation results of the transmittance of the pump laser with different polarization states through the alkali metal vapor cell are given and verified by experiments. The experimental results show that the circularly polarized beam has the weakest absorption, while the linearly polarized laser beam is absorbed the strongest. The achieved measurement accuracy stands at an impressive 98.83 %. This work provides a simple and easy-to-use way to measure the polarization state of the laser beam used in the vapor cell devices, particularly the microfabricated prototypes with limited space.

High-precision measurements of terahertz polarization states with a fiber coupled time-domain THz spectrometer

We present a new method for high precision measurements of polarization rotation in the frequency range from 0.2 to 2.2 THz using a fiber coupled time-domain THz spectrometer. A free standing wire-grid polarizer splits THz light into orthogonal components that are then measured by two separate detectors simultaneously. We theoretically model the uncertainties introduced by optical component non-idealities and predict that we may expect to achieve accuracies of 0.8% when anti-symmetrizing the response with respect to an applied field. Anti-symmetrization improves accuracy by more than four orders of magnitude. We demonstrate this method on a 2D electron gas in magnetic field and show that we achieve a precision of 20 μrad (1.1 mdeg) for small polarization rotation angles. A detailed description of the technique and data analysis procedure is provided, demonstrating its capability to precisely measure polarization states in the 0.2 to 2.2 THz range.

Robust Classical and Quantum Polarimetry with a Single Nanostructured Metagrating.

We formulate a new conceptual approach for one-shot complete polarization state measurement with nanostructured metasurfaces applicable to classical light and multiphoton quantum states by drawing on the principles of generalized quantum measurements based on positive operator-valued measures. Accurate polarization reconstruction from a combination of photon counts or correlations from several diffraction orders is robust with respect to even strong fabrication inaccuracies, requiring only a single classical calibration of the metasurface transmission. Furthermore, this approach operates with a single metagrating without interleaving, allowing for a reduction in metasurface size while preserving high transmission efficiency and output beam quality. We theoretically obtained original metasurface designs, fabricated the metasurface from amorphous silicon nanostructures deposited on glass, and experimentally confirmed accurate polarization reconstruction of laser beams. We also anticipate robust operation under changes in environmental conditions, opening new possibilities for space-based imaging and satellite optics.

Polarization Orientation Method Based on Remote Sensing Image in Cloudy Weather

Autonomous navigation technology is a core technology for intelligent operation, allowing the vehicles to perform tasks without relying on external information, which effectively improves the concealability and reliability. In this paper, based on the previous research on the bionic compound eye, a multi-channel camera array with different polarization degrees was used to construct the atmospheric polarization state measurement platform. A polarization trough threshold segmentation algorithm was applied to study the distribution characteristics and characterization methods of polarization states in atmospheric remote sensing images. In the extracted polarization feature map, the tilting suggestion box was obtained based on the multi-direction window extraction network (similarity-based region proposal networks, SRPN) and the rotation of the suggestion box (Rotation Region of interests, RRoIs). Fast Region Convolutional Neural Networks (RCNN) was used to screen the suggestion boxes, and the Non-maximum suppression (NMS) method was used to select the angle, corresponding to the label of the suggestion box with the highest score, as the solar meridian azimuth in the vehicle coordinate system. The azimuth angle of the solar meridian in the atmospheric coordinate system can be calculated by the astronomical formula. Finally, the final heading angle can be obtained according to the conversion relationship between the coordinate systems. By fitting the measured data based on the least Square method, the slope K value is −1.062, RMSE (Root Mean Square Error) is 6.984, and the determination coefficient R-Square is 0.9968. Experimental results prove the effectiveness of the proposed algorithm, and this study can construct an autonomous navigation algorithm with high concealment and precision, providing a new research idea for the research of autonomous navigation technology.

On‐Chip Plasmonic Vortex Interferometers (Laser Photonics Rev. 16(10)/2022)

Optical Interferometers In article number 2200242, Yuan-Hao Lang, Quan Xu, and colleagues have developed a new form of optical interferometers by customizing the plasmonic vortex generation from two spin channels. In several square wavelengths, plasmonic vortex interferometer constructs interference field with subwavelength fine structure, demonstrating the measurement of polarization state, spin, and orbital angular momentum of the incident light beam.

A Torsion Relative Angle Measurement Method Based on Fiber-Loop Ring-Down with Intra-Cavity Amplification

Background: The fiber-loop ring-down spectroscopy technique has the benefits of optical fiber sensors and also has many unique advantages. Combined with various sensor structures, the FLRD system can achieve different physical, chemical, and biological sensors. Objective: To find a way to solve the problems of light fluctuation and low sensitivity, high sensitivity, and reliability torsion relative angle measurement system is necessary. Methods: The torsion relative angle measurement is achieved by using the fiber loop ring-down intra- cavity amplification. The sensitivity, correlation coefficient, and repeatability are analyzed with the experiment. Results: The sensitivity and correlation coefficient of the proposed system are 4.05 μs/° and 0.9996, respectively. The repeated experiments show that the standard deviation is 9.592×10-4. Conclusion: The proposed measurement method provides a way to solve the problems of light fluctuation and low sensitivity and has promising applications in the optically active solutions, fiber radial stress birefringence and polarization state measurement of fiber lasers.

Single-shot measurement of polarization state at low light field using Mueller-mapping star test polarimetry

Polarization measurement is often completed in the scenes with low signal-to-noise ratio (SNR) in some fields, such as biomedical sensing and remote sensing, resulting in the requirement for the polarimeter to conduct the real-time measurement of the polarization state at low light field. However, accurate measurement of the polarization state at low light field is challenging due to background-noise interference. Herein, we develop a Mueller-mapping star test polarimetry (MMSTP) method by quantitatively linking the Mueller matrix of a space-variant birefringence device and the polarization-dependent intensity distribution. Combined with a normalized least-squares method that accounts for the spatial distribution characteristics of photons at low light field, in addition to a low-pass fast-Fourier-transform filter, the proposed method can calculate polarization states from a single irradiance image at low light field with higher accuracy. Experimental results show that the proposed method can significantly improve the measurement accuracy of polarization states compared with the classical division-of-time Stokes polarimeters at low light field.

Direct high-resolution resonant Raman scattering measurements of dynamic nuclear spin polarization states of an InAs quantum dot

We report on the direct measurement of the electron spin splitting and the accompanying nuclear Overhauser (OH) field, and thus the underlying nuclear spin polarization (NSP) and fluctuation bandwidth, in a single InAs quantum dot under resonant excitation conditions with unprecedented spectral resolution. The electron spin splitting is measured directly via resonant spin-flip single photon Raman scattering detected by superconducting nanowires to generate excitation-emission energy maps. The observed two-dimensional maps reveal an OH field that has a non-linear dependence on excitation frequency. This study provides new insight into earlier reports of so-called avoidance and tracking, showing two distinct NSP responses directly by the addition of a emission energy axis. The data show that the polarization processes depend on which electron spin state is optically driven, with surprising differences in the polarization fluctuations for each case: in one case, a stabilized field characterized by a single-peaked distribution shifts monotonically with the laser excitation frequency resulting in a nearly constant optical interaction strength across a wide detuning range, while in the other case the previously reported avoidance behavior is actually the result of a nonlinear dependence on the laser excitation frequency near zero detuning leading to switching between two distinct mesoscopic nuclear spin states. The magnitude of the field, which is as large as 400 mT, is measured with sub-100 nuclear spin sensitivity. Stable/unstable points of the OH field distribution are observed, resulting from the non-linear feedback loop in the electron-trion-nuclear system. Nuclear spin polarization state switching occurs between fields differing by 160 mT at least as fast as 25 ms. Control experiments indicate that the strain-induced quadrupolar interaction may explain the measured OH fields.

Privacy amplification of entanglement parametric-down conversion based quantum key distribution via quantum logistic map for photon bases choice

This paper proposes a new quantum key distribution (QKD) protocol, namely the pseudo-random bases entangled-photons based QKD (PRB-EPQKD) protocol. The latest mainly focuses on the privacy amplification analysis of spontaneous parametric down conversion (SPDC) entangled photon source based QKD using quantum logistic map (QLM) as pseudo-random number generator (PRNG) for photon polarization state measurement bases choice. For this reason, the SPDC wave function is derived and the probability distribution is deduced. The comparison shows that, this probability follows Poisson distribution, implying that the photons pairs produced are independent. Based on this, the quantum bit error rate (QBER) is evaluated and consequently the secure key rate. Simulations show that this protocol is particularly efficient as regard to the maximum tolerable communication distance and the secure key size as well. The fact that, an eavesdropper must crack the chaotic and the QKD systems simultaneously in order to extract any useful information concerning the encryption key makes the key generation protocol more private as compared to existing ones.

Measurement of full polarization states with hybrid holography based on geometric phase.

We propose a method for measuring the full polarization states of a light field by using hybrid polarization-angular multiplexing digital holography based on geometric phase. Through acquiring the geometric phase distribution of the whole light field by only recording a composite hologram, and according to quantitative relationship between the geometric phase and polarization state, the Stokes parameters of a light field can be calculated. Compared with other methods, this method can be used to obtain the complex amplitude information of the light field simultaneously without requiring other complex devices or elements to be adjusted, thus enabling dynamic polarization state measurement. The measurement results of the light fields generated by standard polarized optical elements, vortex half-wave retarder, and liquid crystal depolarizer verified this method's feasibility and validity.

Polarization-resolved Stokes-Mueller imaging: a review of technology and applications.

Polarization microscopy, a powerful optical tool to study anisotropic properties of biomolecules, provides better microstructural information of a sample as compared with conventional optical microscopic techniques. The measurement and analysis of polarization states of light can be performed using both Jones matrix as well as Stokes algebra. Further, the details of optical properties of specimen are characterized by Mueller matrix. However, the application of Jones calculus is limited to perfectly polarized light, but Stokes-Mueller polarimetry is emerging as a promising tool for tissue imaging due to its application irrespective of polarization state of the light. In this review article, we explain the development of Stokes-Mueller formalism in context of linear optics. Furthermore, application of Mueller matrix decomposition (MMD) method to derive sample properties is demonstrated in several bio-medical studies.

Polarization state generation and measurement with a single metasurface.

The constituent elements of metasurfaces may be designed with explicit polarization dependence, making metasurfaces a fascinating platform for new polarization optics. In this work we show that a metasurface grating can be designed to produce arbitrarily specified polarization states on a set of defined diffraction orders given that the polarization of the incident beam is known. We also demonstrate that, when used in a reverse configuration, the same grating may be used as a parallel snapshot polarimeter, requiring a minimum of bulk polarization optics. We demonstrate its use in measuring partially polarized light, and show that it performs favorably in comparison to a commercial polarimeter. This work is of consequence in any application requiring lightweight, compact, and low-cost polarization optics, polarimetry, or polarization imaging.

Metrology of Single Photons for Quantum Information Technologies

A new approach is proposed for the metrology of optical measurements – the quantum metrology of photons. The specific nature of measurements of quantum polarization states of single and polarization-entangled photons is examined. The fundamental objectives of the modern metrology of photons are formulated.

Tau Lepton Reconstruction in ATLAS

Tau leptons play a key role in many measurements and searches within and beyond the Standard Model of particle physics performed at the LHC. We present here the performance of the reconstruction, identification and energy measurement algorithms for hadronic tau lepton decays currently used by the ATLAS collaboration. We also introduce a new reconstruction method which uses the individual charged and neutral hadrons in tau decays to improve the 4-momentum resolution, while also providing increased sensitivity to tau polarization and Higgs CP state measurements.

Single-Shot Measurement of Temporally-Dependent Polarization State of Femtosecond Pulses by Angle-Multiplexed Spectral-Spatial Interferometry.

We demonstrate that temporally-dependent polarization states of ultrashort laser pulses can be reconstructed in a single shot by use of an angle-multiplexed spatial-spectral interferometry. This is achieved by introducing two orthogonally polarized reference pulses and interfering them with an arbitrarily polarized ultrafast pulse under measurement. A unique calibration procedure is developed for this technique which facilitates the subsequent polarization state measurements. The accuracy of several reconstructed polarization states is verified by comparison with that obtained from an analytic model that predicts the polarization state on the basis of its method of production. Laser pulses with mJ-level energies were characterized via this technique, including a time-dependent polarization state that can be used for polarization-gating of high-harmonic generation for production of attosecond pulses.

Real-time polarization state measurement based on a birefringent crystal wedge

We present a method of single-shot polarization state measurement based on a birefringent crystal wedge. The phase delay and amplitude angle of detected light are encoded into two groups of fringes through the interference in a crystal wedge and further decoded by fringe position locations. This method has the merit of real-time measurement, a compact set-up and simple calibration. The principle, set-up, calibration and error analysis are presented in details. In the end, a single-shot measurement set-up with 80 kHz temporal resolution is demonstrated to investigate the molecule dynamic behaviour in a TN liquid crystal under a rectangular voltage.

Ultracompact metasurface in-line polarimeter

In-line polarimeters perform nondestructive polarization measurements of optical signals, and play a critical role in monitoring and controlling the polarization environment in, for example, optical networks. While current in-line polarimeters are constructed with multiple optical components, either fabricated into an optical fiber or using free-space optics, we present here a novel architecture conducive to monolithic on-chip integration. This enables the scalable fabrication of high-performance polarization sensors with exceptional stability, compactness, and speed. The method relies on the detection of the highly polarization-dependent scattered field of a subwavelength antenna array known as a metasurface, and is shown here to provide polarization state measurements matching those of a state-of-the-art commercial polarimeter.

Polarization-sensitive interleaved optical coherence tomography

We introduce a new strategy for single-mode fiber based polarization-sensitive (PS-) optical coherence tomography (OCT) using orthogonally polarized optical frequency combs (OFC) in the sample arm. The two OFCs are tuned to be interleaved in the spectral domain, permitting simultaneous measurement of both polarization states from the same spatial region C close to the location of zero pathlength delay. The two polarization states of the beam in the sample arm are demultiplexed by interpolation after performing wavelength stabilization via a two-mirror calibration method. The system uses Jones matrix methods to measure quantitatively the round-trip phase retardation B-scans in the sample. A glass plate and quarter-wave plate were measured to validate the accuracy of the birefringence measurement. Further, we demonstrated the potential of this system for biomedical applications by measurement of chicken breast muscle.

Angle-multiplexed spatial-spectral interferometry for simultaneous measurement of spectral phase and polarization state

A novel method to simultaneously extract the polarization state and relative spectral phase of an ultrashort laser pulse from an angle-multiplexed spatial-spectral interferometric measurement is proposed and experimentally demonstrated. Spectral interference is produced between an arbitrary polarized signal pulse and two orthogonal linearly polarized reference pulses. The accuracy of this technique has been verified by reconstructing the known relative spectral phase arising from material dispersion and the known elliptical polarization state. Measurement of the relative spectral phase and the spatially variable polarization state of a radially polarized pulse is also demonstrated. An additional independent measurement of the spectral phase of reference pulses provides absolute spectral and temporal characteristics of the signal pulse.

Improved measurement of polarization state in terahertz polarization spectroscopy

A calibration scheme is presented for improved polarization state measurement of terahertz pulses. In this scheme the polarization response of a two-contact terahertz photoconductive detector is accurately measured, and is used to correct for the impact of the nonidealities of the detector. Experimental results show excellent subdegree angular accuracy and at least 60% error reduction with this scheme.