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We present a method of laser frequency stabilization based on the linear dichroism signal in a transverse magnetic field. This method is similar to the DAVLL (Dichroic Atomic Vapor Laser Lock) method. It differs from DAVLL and from its existing modifications primarily by the fact that it uses signals of linearly polarized light caused by alignment, rather than circular refraction caused by orientation, and therefore allows us to obtain error signals at the magnetic field modulation frequency (or its second harmonic) by extremely simple means. The method allows the laser frequency to be stabilized in the vicinity of the low-frequency transition in the D1 line of Cs; it does not require strong magnetic fields or careful shielding of cells containing cesium atoms. Although the absorption line in a gas-filled cell is typically gigahertz wide, the achievable resolution, limited by the signal-to-noise ratio of photon shot noise, can reach units or tens of kilohertz in a one hertz bandwidth. [ABSTRACT FROM AUTHOR]

This review article aims to address common research questions in passive polarized vision for robotics. What kind of polarization sensing can we embed into robots? Can we find our geolocation and true north heading by detecting light scattering from the sky as animals do? How should polarization images be related to the physical properties of reflecting surfaces in the context of scene understanding? This review article is divided into three main sections to address these questions, as well as to assist roboticists in identifying future directions in passive polarized vision for robotics. After an introduction, three key interconnected areas will be covered in the following sections: embedded polarization imaging; polarized vision for robotics navigation; and polarized vision for scene understanding. We will then discuss how polarized vision, a type of vision commonly used in the animal kingdom, should be implemented in robotics; this type of vision has not yet been exploited in robotics service. Passive polarized vision could be a supplemental perceptive modality of localization techniques to complement and reinforce more conventional ones. [ABSTRACT FROM AUTHOR]

This study investigated the influence of different linearly polarized spectrum lights on locusts polartactic response characteristics linearly polarized vector sensitivity mode and polartactic response) by using linearly polarized spectrum vector light module and experimental device. The objective was to clarify the vector sensitivity characteristics and functional effect of linearly polarized light spectrum intensity on locusts polartactic response, determine the influence specificity of linearly polarized spectrum illumination properties on locusts polarization-related behavior. When spectrum and illumination were constant, locusts polartactic response, presenting the response feature of sine and cosine function change specificity, was related to spectrum attribute. The visual acuity effect stimulated by violet spectrum was the best, whereas the optical distance modulation effect induced by orange spectrum was the strongest. When illumination was enhanced, locusts vector sensitivity mode shifted to present the specific sensitivity prompted by light intensity at long distance and inhibited by light intensity at short distance. Moreover, the regulating function of violet spectrum was the strongest, and the regulatory mutation effect of orange spectrum was the least significant. Simultaneously, locusts polartactic sensitivity to 300° vector at 100 lx, whereas to 240° vector at 1000 lx of linearly polarized violet light was the strongest. Locusts polartactic aggregation and visual tendency sensitivity to 90° vector at 100 lx, whereas to 270° vector at 1000 lx of linearly polarized violet light was the strongest. The heterogeneous regulation function of different linearly polarized spectrum couplings with light intensity led to significant variations in locusts vector sensitivity mode. This was derived from the antagonistic and specific tuning characteristics of locusts polartactic vision, reflecting the integrated output effect of locusts vector dependence regulated by linearly polarized spectrum intensity attribute. The findings were significant for the construction of pest polarization induction light sources and the investigation of the sensitive physiology pathway of locusts polarization vision. [ABSTRACT FROM AUTHOR]

Periodic nanostructures, including gratings, which have been widely used in the fields of photonics and plasmonics, are generally fabricated through electron beam lithography, photolithography, or laser-induced periodic surface structure (LIPSS) formation. Although photomasks or photoresists are not necessary for the preparation of LIPSSs, a laser is required as a coherent light source. Here, we propose a photoelectrochemical bottom-up approach to obtain semitransparent periodic nanostructures using an incoherent continuous light source. Lead oxide nanoband arrays are formed simply by irradiating linearly polarized light to a potential-controlled indium-tin oxide electrode in the presence of Pb2+ ions. The polarized light causes anisotropic growth of lead oxide parallel to the polarization direction, and interference between incident light and light scattered from the nanostructures gives rise to the periodicity. The pitch of the subwavelength scale can be controlled by the irradiation light wavelength. [ABSTRACT FROM AUTHOR]

We present a method of laser frequency stabilization based on the linear dichroism signal in a transverse magnetic field. This method is similar to the DAVLL (Dichroic Atomic Vapor Laser Lock) method. It differs from DAVLL and from its existing modifications primarily by the fact that it uses signals of linearly polarized light caused by alignment, rather than circular refraction caused by orientation, and therefore allows us to obtain error signals at the magnetic field modulation frequency (or its second harmonic) by extremely simple means. The method allows the laser frequency to be stabilized in the vicinity of the low-frequency transition in the D1 line of Cs; it does not require strong magnetic fields or careful shielding of cells containing cesium atoms. Although the absorption line in a gas-filled cell is typically gigahertz wide, the achievable resolution, limited by the signal-to-noise ratio of photon shot noise, can reach units or tens of kilohertz in a one hertz bandwidth.

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This review article aims to address common research questions in passive polarized vision for robotics. What kind of polarization sensing can we embed into robots? Can we find our geolocation and true north heading by detecting light scattering from the sky as animals do? How should polarization images be related to the physical properties of reflecting surfaces in the context of scene understanding? This review article is divided into three main sections to address these questions, as well as to assist roboticists in identifying future directions in passive polarized vision for robotics. After an introduction, three key interconnected areas will be covered in the following sections: embedded polarization imaging; polarized vision for robotics navigation; and polarized vision for scene understanding. We will then discuss how polarized vision, a type of vision commonly used in the animal kingdom, should be implemented in robotics; this type of vision has not yet been exploited in robotics service. Passive polarized vision could be a supplemental perceptive modality of localization techniques to complement and reinforce more conventional ones.

Locust and grasshopper plagues pose a serious threat to crop production in many areas worldwide. However, there is a lack of effective, quick-acting methods to control such outbreaks. Methods exploiting the phototactic response of these insects are receiving increasing attention. The current study investigated the effect of linearly polarized and unpolarized light on locust phototactic and polarotactic responses, in particular the function of their dorsal rim area (DRA) and non-DRA visual fields. The results showed that the polarotactic function weight of DRA vision was stimulated by linearly polarized ultraviolet (UV) and violet light, the phototactic function weight was induced by blue, green, and orange light, and under linearly polarized light, the functional effect of DRA vision was strongest in response to linearly polarized violet light. Moreover, the locust visual response effect was related to spectral light attributes, with the linear polarization effect intensifying in response to the short-range vision sensitivity of non-DRA visual fields, whereas DRA vision regulated the short-range sensitivity of compound eye vision. When illumination increased, the synergistic enhancement effects of linearly polarized ultraviolet and violet light were significant, whereas the visual sensitivity was restricted significantly by linearly polarized blue, green, or orange light. Thus, non-DRA vision determined, while DRA vision enhanced, the phototactic response sensitivity, whereas, in linearly polarized UV or violet light, non-DRA vision determined, while DRA vision enhanced, the visual trend and polarotaxic aggregation sensitivity, with opposite effects in linearly polarized blue, green, or orange light. When illumination increased, there was a driving effect caused by linearly polarized violet light on non-DRA vision, whereas at short-wave lengths, the control effect induced by linearly polarized orange light was optimal; however, the photo-induced effect of linearly polarized violet light and the visual distance control effect of linearly polarized orange light were optimal. These results provide theoretical support for the photo-induced mechanism of the locust visual response effect and for the development of linearly polarized light sources for the environmentally friendly prevention and control of locust populations. [ABSTRACT FROM AUTHOR]

Manipulating and detecting polarization states of light plays an important role in developing technology in various fields, such as remote sensing, medical phototherapy, and quantum information. However, polarization control in mid-infrared (mid-IR) wavelengths, especially longer than 10 µm, is obstructed by the limitation of material properties. Searching for materials and designing structures that respond to polarized light in this spectral range is still challenging. In this work, triangular core–shell AlGaAs/GaAs nanowires are numerically studied using the finite difference method. The effects of the core shift and rotating angle on the absorption coefficients are concentrated. Highly anisotropic absorption of polarized light in the mid-IR range is found when the core shifts upward and downward. Our results show that this anisotropic property is influenced by the symmetries of electron quantum states confined in the system. Broadband absorption wavelengths from 9.7 to 17.5 µm are unexpectedly found in the structure with appropriate system size. Our finding indicates that triangular core–shell nanowires are a potential platform for next-generation photonic devices capable of manipulating polarized light in a wide range of mid-IR wavelengths.

Copyright of Laser Technology is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new approach to fabricate ordered complex surface patterns is established upon linearly polarized light (LPL) irradiation with a continuous wave laser. Distinct from typical laser‐induced periodic surface structures, the ordered patterns are formed through unique topographical transitions of submicrometer pillar arrays of an azo molecular glass, when irradiated with LPL at 532 nm. As revealed by microscopic investigation and optical simulation, the structure formation results from the deformation of the original pillars along the electric vibration direction of LPL and growth of new structures in the regions between the pillars owing to the nonuniformly distributed light intensity. Spontaneously shaped structures are also induced by increasing LPL irradiation time. The ordered surface patterns are then formed by coalescence of the gradually erased pillars with these newly formed structures. The morphologies and orientation of the patterns are precisely controlled by adjusting the conditions, i.e., the polarization direction of LPL relative to the hexagonal lattice of the pillar arrays and the irradiation time. These observations lead to the deep understanding of unique light–matter interaction effects on the material in pillar array architecture. This new method can be used to create various complex surface patterns in submicrometer scale for many applications. [ABSTRACT FROM AUTHOR]

The absorption of linearly polarized light by 133Cs atoms is desired to be well known in many applications of atomic physics. For implementing this requirement, a simplified analytical form for the absorption of linearly polarized light by 133Cs atoms with optically resolved hyperfine structure is derived. Based on the obtained analytical form, optical absorption cross-sections of 133Cs atoms are simulated. An experiment is designed to further study the absorption of linearly polarized light by 133Cs atoms. Theory and experiment show that the influence of linearly polarized light on the distribution of 133Cs atoms will in turn affect the optical absorption. In order to demonstrate this kind of influence, an example for the measurement of the 133Cs vapor density is shown theoretically and experimentally, and a method of polynomial fit is proposed to reduce this influence.

The transfer matrix method adopted to solve the linearly polarized light propagation problem in order to study the occurrence of absorption transitions for Aluminum zigzag thin films. For different incident light, azimuthal angles, arms number and lengths, the optical results showed that the intensity of absorption peak of s-polarization remains constant as the incident light angle increases, while the intensity of absorption peaks for p-polarization increases. According to the variations of spectra for different azimuthal angles, the results of p-polarization are opposite to s polarization. Also, changing the number of arms from two to three, three to four and four to five, shift the peaks of absorption spectrum towards longer (red shift), shorter (blue shift) and longer wavelengths (red shift), respectively. This behavior can be observed for zigzag nano-structure with different arm lengths.

One of the essential calibration procedures for the motional Stark effect (MSE) diagnostic system includes obtaining the mapping responses of the angle evaluated from the demodulation of the photoelastic-modulated raw signals in the MSE polarimeter to the incident polarized light either parallel or perpendicular to the Lorentz electric field originated from a flux surface of a tokamak plasma. This in-vessel mapping calibration procedure that is practically very time-consuming and tedious has been improved by a newly developed MSE in-vessel calibration system with the capability of remote and automatic operations for the Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. The key design has employed the concept that the polarization state is preserved along an observation line of sight once the polarizer surface, or the wave front of the polarized light, is perpendicular to the line of sight. Comparisons with previous manual calibration procedures confirm this concept is applicable practically. The new remote and automatic calibration activities performed with this new system yield unprecedented angular coverage and resolution in the mapping curves between the incident polarization angles and measured angles. The performance of the new calibration mechanism, free from various time constraints related to scheduling tokamak maintenance period, is virtually limited only by the precision of the motorized rotational stage that mounts the polarized light source on it, which is less than a hundredth of a degree. • Utilization of polarization preservation along a line of sight for system compactness. • Unprecedented angular resolutions in the MSE in-vessel mapping calibration. • Flexibility in integrating MSE in-vessel calibration with tokamak maintenance period. [ABSTRACT FROM AUTHOR]

Directly linearly polarized light emission from organic light‐emitting diodes (OLEDs), as an important functional expansion, is an intriguing and attractive research topic due to its increasing importance in various applications. Until now, however, the limited efficiency and inadequate polarization ratio constitute two major hurdles for real application. In this work, high‐efficiency linearly polarized white OLEDs with an ultrahigh polarization ratio are achieved by using integrated dielectric/metal nanograting and nanorelief speckle image holography metasurfaces. In the devices, the integrated grating behave as a polarizer to select the transverse magnetic wave (TM) component and simultaneously reflect the transverse electric wave (TE) counterpart over the whole emission spectrum, while the metasurfaces gather the otherwise waste TE‐polarized light reflected by the grating and transform it into reusable TM‐polarized light. This synergistic energy‐light recycling system leads to dramatically boosted device efficiency and polarization ratio, i.e., a power efficiency 21.4 lm W−1 (@ 1000 cd m−2), and an extinction ratio of 17.8 dB (@ V = 5 V) for the polarized white OLEDs. The presented paradigm for simultaneous polarization controlling and efficiency boosting in white OLEDs is expected to advance the OLED techniques in device reconfigurability for future multifunctional applications. [ABSTRACT FROM AUTHOR]

• The fully relativistic method for treating the PI process is developed. • Good agreement with theory and experiments. • Multipole effects on the cross section and alignment after PI are assessed. On the basis of the fully relativistic Dirac-Fock treatment of single ionization by a linearly polarized photon with regard to the E 1, M 1, E 2, M 2, and E 3 multipoles of the radiative field as well as their interference, we have assessed the influence of multipole effects on the cross sections and alignment parameters A 20 and A 22 of the residual ions, taking the 3 p 3/2 and 3 d 3/2 vacancies of selected Zn and Zn-like Kr6+, Cd18+, and Xe24+ ions as examples. Starting from the most general method of density matrix theory, we carried out specific analytic expressions in terms of the reduced matrix elements of multipole fields, corresponding to different ion-core states. It is shown that the multipole contributions to the photoionization cross sections can be considerable, the character of which becomes more evident as the incident energy and/or atomic number increases. These dramatic influences also lead to a remarkable increase in the alignment parameter A 20 of the residual ions, yet virtually independent of the nuclear charge for A 22. The present results in Coulomb gauge and Babushkin gauge excellently agreed with each other, suggesting that there is a high degree of convergence achieved in this study. Comparison of our results with experimental data and other theoretical predictions, when available, is made. [ABSTRACT FROM AUTHOR]

• The optically organized and bound 2D clusters (trimer, tetramer and pentamer) of multiple Au nanoparticles (NPs) induced by a linearly polarized (LP) Gaussian beam is studied theoretically. • Via the surface integration of Maxwell's stress tensor, the optical forces and torques upon every Au NPs are analyzed. • The numerical results illustrate that 2D stable-equilibrium clusters with wavelength-scale gaps can be produced at an off-focal plane of a LP Gaussian beam, besides 1D linear array patterns. • These nanoparticles are driven to transversely spin by the optical torque even though irradiated by a LP light. • There is a range of the off-focal plane for inducing these ordered patterns. The mechanism of optically organized and bound 2D clusters of multiple Au nanoparticles (NPs) is studied theoretically. Via the surface integration of Maxwell's stress tensor, the optical forces and torques upon every Au NPs are analyzed. The numerical results illustrate that 2D stable-equilibrium clusters (trimer, tetramer and pentamer) with wavelength-scale gaps can be produced at an off-focal plane of a linearly polarized (LP) Gaussian beam, besides 1D linear array patterns. For example, a trimer with an isosceles triangular pattern can be induced. These stably ordered cluster patterns are due to the plasmon-enhanced long-range interaction of light with these coupled Au NPs. Moreover, there is a range of the off-focal plane for inducing these ordered patterns. Our results are in agreement with the previous experiments [Yan et al. Nat. Commun. 2014; 5: 3751]. In addition, we found that these NPs are driven to transversely spin by the corresponding optical torque even though irradiated by a LP light. The study on optomechanics of the light-driven self-assembly of plasmonic colloids can be applied to 2D array patterning, which is worth further exploiting. [ABSTRACT FROM AUTHOR]

Traditional models for beam broadening include both a diffractive term, owing to the source aperture, and a beam 'wandering' term that stems from refractive index variations in the atmosphere. Here we derive a novel beam broadening term that depends on the properties of atmospheric turbulence. The derivation rests on a transport formulation of the propagation problem whereby the magnitude of the electric field is viewed as the density of a fluid, moving in a flow that is driven by the refractive index perturbations. Properties of the transport solutions are obtained using Lagrangian coordinates and are demonstrated to be entirely consistent with existing theory on the subject. The new factor predicts appreciable (25% in our example) increases in beam broadening for applications requiring propagation over very long optical paths and heavy turbulence. [ABSTRACT FROM AUTHOR]

The methods to enhance contrast ratios (CRs) in scattering-type transflective liquid crystal displays (ST-TRLCDs) based on polymer-network liquid crystal (PNLC) cells are investigated. Two configurations of ST-TRLCDs are studied and are compared with the common ST-TRLCDs. According to the comparisons, CRs are effectively enhanced by assembling a linear polarizer at the suitable position to achieve better dark states in the transmissive and reflective modes of the reported ST-TRLCDs with the optimized configuration, and its main trade-off is the loss of brightness in the reflective modes. The PNLC cell, which works as an electrically switchable polarizer herein, can be a PN-90° twisted nematic LC (PN-90° TNLC) cell or a homogeneous PNLC (H-PNLC) cell. The optoelectric properties of PN-90° TNLC and those of H-PNLC cells are compared in detail, and the results determine that the ST-TRLCD with the optimized configuration using an H-PNLC cell can achieve the highest CR. Moreover, no quarter-wave plate is used in the ST-TRLCD with the optimized configuration, so a parallax problem caused by QWPs can be solved. Other methods for enhancing the CRs of the ST-TRLCDs are also discussed.

[Display omitted] • Highly anisotropic absorption coefficients are found when the core of a triangular core–shell nanowire shifts upward and downward. • Optical transitions are predictable by considering the symmetries of electron quantum states. • Broadband absorption of polarized mid-infrared light is unexpectedly found. Manipulating and detecting polarization states of light plays an important role in developing technology in various fields, such as remote sensing, medical phototherapy, and quantum information. However, polarization control in mid-infrared (mid-IR) wavelengths, especially longer than 10 µm, is obstructed by the limitation of material properties. Searching for materials and designing structures that respond to polarized light in this spectral range is still challenging. In this work, triangular core–shell AlGaAs/GaAs nanowires are numerically studied using the finite difference method. The effects of the core shift and rotating angle on the absorption coefficients are concentrated. Highly anisotropic absorption of polarized light in the mid-IR range is found when the core shifts upward and downward. Our results show that this anisotropic property is influenced by the symmetries of electron quantum states confined in the system. Broadband absorption wavelengths from 9.7 to 17.5 µm are unexpectedly found in the structure with appropriate system size. Our finding indicates that triangular core–shell nanowires are a potential platform for next-generation photonic devices capable of manipulating polarized light in a wide range of mid-IR wavelengths. [ABSTRACT FROM AUTHOR]

Blood oxygen saturation (SpO2) measurement is a routinely performed clinical procedure involved in the diagnosis of several critical diseases. However, the most commonly used SpO2 measuring device, known as oximeter, becomes unreliable in the absence of proper body contact. A non-contact, non-invasive, real-time device is desirable for accurate measurement and continuous monitoring of SpO2. This paper presents a polarized imaging-based integrated solution for SpO2 measurement. The polarization filters are used to separate light components reflecting from deep and superficial layers of skin. The ratio of intensities of the two components is found to have a linear relationship with SpO2 levels. In contrast to the existing SpO2 measurement techniques, the proposed method uses a single light source. The experiments are performed with 15 human subjects (11 male and 4 female) using different wavelengths of light. A statistically significant relationship is observed between SpO2 and the intensity ratios for red light (correlation coefficient \textrm r = 0.6426 with p = 0.001965 and mean error = 0.0626). The experiments are repeated using white light, and a similar relationship is observed ( \textrm r = 0.5603 with p = 0.00947 and mean error = −0.9289). Furthermore, the Bland–Altman analysis shows that the results of the proposed method are consistent with the reference data. This suggests that a real-time integrated polarized imaging-based SpO2 measurement device can be developed based on the proposed method. [ABSTRACT FROM PUBLISHER]

This study theoretically investigates plasmon-mediated optical binding forces, which are exerted on metal homo or heterodimers, induced by the normal illumination of a linearly polarized plane wave or Gaussian beam. Using the multiple multipole method, we analyzed the optical force in terms of Maxwell׳s stress tensor for various interparticle distance at some specific wavelengths. Numerical results show that for a given wavelength there are several stable equilibrium distances between two nanoparticles (NPs) of a homodimer, which are slightly shorter than some integer multiples of the wavelength in medium, such that metal dimer acts as bonded together. At these specific interparticle distances, the optical force between dimer is null and serves a restoring force, which is repulsive and attractive, respectively, as the two NPs are moving closer to and away from each other. The spring constant of the restoring force at the first stable equilibrium is always the largest, indicating that the first stable equilibrium distance is the most stable one. Moreover, the central line (orientation) of a dimer tends to be perpendicular to the polarization of light. For the cases of heterodimers, the phenomenon of stable equilibrium interparticle distance still exists, except there is an extra net photophoretic force drifting the heterodimer as one. Moreover, gradient force provided by a Gaussian beam may reduce the stability of these equilibriums, so larger NPs are preferred to stabilize a dimer under illumination of Gaussian beam. The finding may pave the way for using optical manipulation on the gold or silver colloidal self-assembly. [ABSTRACT FROM AUTHOR]

In this study, we used photo electron emission microscopy (PEEM) to investigate the growth of α -sexithiophene ( α -6T) on Ag(111) surfaces. The experiments were carried out with linearly polarized ultraviolet-light (Hg lamp with hν =4.9 eV) in order to probe the alignment of the molecules on the surface. In particular, we acquired images before, during, and after growth while changing the polarization in a stepwise manner. For the stationary states of the clean and the α -6T covered surfaces, we monitored the local electron yield and the intensity of the ultraviolet C-light (100–280 nm) reflected from the whole sample using PEEM and a photodiode, respectively. Due to the high ionization potential ( IP > 5 eV ) , there is no direct photoelectron emission from the organic crystallites. However, the photoelectron emission of the metal/organic interface is influenced by anisotropic absorption of the incident light beam, since the adsorbed molecules act as dichroic filters with distinct orientations. [ABSTRACT FROM AUTHOR]

Blood molecules are optically active molecules. They have the ability to alter the polarization properties of light. This paper investigates the effect of blood pulsation variation on the polarization properties of linearly polarized light. This paper presents a new noninvasive noncontact blood pulsation measurement technique. Linearly polarized light has been allowed to transmit through the fingertips of a person and degree of linear polarization for transmitted part of the light has been calculated using polarized images. Experimental results show a strong correlation between the blood pulsation rate and the measured degree of linear polarization. The standard correlation coefficient value for the experiment with laser light source and two polarizers in the light path is 0.9484. Similarly for dc light source the correlation coefficient values are 0.9410 and 0.92 with two polarizers and one polarizer, respectively. Statistical analysis of the collected data has been done to measure the accuracy of the method. It shows that an accurate, low cost, and simple polarization-based blood pulsation measurement device can be developed by following the experiment performed with laser light source which could offer significant benefits to primary healthcare. [ABSTRACT FROM PUBLISHER]

• An analytical form of the absorption of linearly polarized light is derived. • The influence of linearly polarized light on atomic distribution is revealed. • A method to reduce this influence is proposed for practical applications. The absorption of linearly polarized light by 133Cs atoms is desired to be well known in many applications of atomic physics. For implementing this requirement, a simplified analytical form for the absorption of linearly polarized light by 133Cs atoms with optically resolved hyperfine structure is derived. Based on the obtained analytical form, optical absorption cross-sections of 133Cs atoms are simulated. An experiment is designed to further study the absorption of linearly polarized light by 133Cs atoms. Theory and experiment show that the influence of linearly polarized light on the distribution of 133Cs atoms will in turn affect the optical absorption. In order to demonstrate this kind of influence, an example for the measurement of the 133Cs vapor density is shown theoretically and experimentally, and a method of polynomial fit is proposed to reduce this influence. [ABSTRACT FROM AUTHOR]

We report a study on the enhancement of linearly p-polarized output power in long pulse (2-20 ms) multimode operation of single rod Nd:YAG laser. Laser resonator was designed using a simple optical scheme with a tilted 90° quartz rotator and a re-entering feedback mirror placed at appropriate location. A p-polarized average output power of 215 W has been achieved with a slope efficiency of 4.5%, which is on higher side for a typical long pulse single rod Nd:YAG laser system. It has been verified experimentally that the depolarization losses can be reduced significantly from a value of ~34% to ~9%. Further, this scheme has resulted in a significant enhancement (more than 80%) of p-polarized output power as compared to placing a polarizer in the resonator. This long pulse p-polarized laser will be useful in various material processing applications and nonlinear frequency conversions. [ABSTRACT FROM AUTHOR]

In the inter-satellite optical communications, background light is an important factor that worsens the acquisition performance and tracking precision of the system. In general, optical filters are applied in eliminating background light. But the bandwidth of the optical filter is a bottleneck for improving the performance of the optical system further. We propose a new method for decreasing background light, in which linearly polarized light is employed as the beacon light. The theoretical model of acquisition probability is derived. Contrastive analysis is performed, among the system with the pure optical filter, the system using the linearly polarized light and the system with the circularly polarized light. Numerical simulations and experimental verification lead to the conclusion that acquisition probability of the system with linearly polarized light is greater than that of the other systems, and this approach is effective. This work can benefit the design of inter-satellite optical communication system. [ABSTRACT FROM AUTHOR]

Abstract: The CALIPSO satellite mission consistently measures volume (including molecule and particulate) light depolarization ratio of ∼2% for smoke, compared to ∼1% for marine aerosols and ∼15% for dust. The observed ∼2% smoke depolarization ratio comes primarily from the nonspherical habits of particles in the smoke at certain particle sizes. In this study, the depolarization of linearly polarized light by small sphere aggregates and irregular Gaussian-shaped particles is studied, to reveal the physics between the depolarization of linearly polarized light and smoke aerosol shape and size. It is found that the depolarization ratio curves of Gaussian-deformed spheres are very similar to sphere aggregates in terms of scattering-angle dependence and particle size parameters when particle size parameter is smaller than 1.0π. This demonstrates that small randomly oriented nonspherical particles have some common depolarization properties as functions of scattering angle and size parameter. This may be very useful information for characterization and active remote sensing of smoke particles using polarized light. We also show that the depolarization ratio from the CALIPSO measurements could be used to derive smoke aerosol particle size. From the calculation results for light depolarization ratio by Gaussian-shaped smoke particles and the CALIPSO-measured light depolarization ratio of ∼2% for smoke, the mean particle size of South-African smoke is estimated to be about half of the 532nm wavelength of the CALIPSO lidar. [Copyright &y& Elsevier]