bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstration of a compact polarisation based two-dimensional multimode optical fibre space switch as optical fibre sensor multiplexer
Authors: Berghmans Francis , Decréton Marc , Thienpont Hugo , Nasilowski Tomasz , Zdrodowski Krzysztof , Radomski Kornel , Bekiesza Artur , Carnicer Yolanda , Küfner Stefan , Küfner Maria , Veretennicoff Irina
Published: February 2023

We constructed two polarisation based space division switches, using nematic liquid crystal variable retarders (LCVR) or ferro-electric liquid crystal polarisation rotators (FLC). Our systems have the potential of establishing a bandwidth transparent relation between 1 input and 9 output multimode optical fibres. [1] To shift a polarised light beam from the input to one of the nine possible outputs, we use a combination of commercially available large aperture LCVRs or FLCs and birefringent calcite [CaCO3] crystals (BC). This yields easily controllable modules for unidirectional beam displacement. Since each LCVR or FLC only needs two control voltage amplitudes, one for zero phase retardance and one for π phase retardance the complete system can be controlled with only four bits. The input light is provided through a GRIN collimating lens terminated singlemode optical fibre, whereas the light exiting the last BC is coupled in 1 out of 9 possible output fibres located in a two-dimensional PMMA (PolyMethyl MethAcrylate) fibre array holder fabricated with deep proton lithography. This technique allows to position the fibres with a ± 2 pm accuracy. The compact system construction is depicted in figure 1. The maximum frequency at which the LCVRs can be driven and hence, at which switching between two fibres is possible, is on the order of 30 Hz. Using a Nippon Sheet Glass Planar Microlens (DI-PML®) array to couple light exiting the last BC in the optical fibres located in the PMMA array holder, we obtain the losses and cross-talk ratios given in table 1.
Temperature dependence on the visibility limits in fibre-optic Michelson interferometric sensors with birrefringence compensation
Authors: Arce-Diego J.L. , Echevarria-Cuenca J. , Cobo A. , López-Higuera J.M.
Published: February 2023

In interferometric fibre optic sensor constructed using conventional low-bi fibres, random fluctuations in the state of the polarization (SOP) of the interfering beams give rise to variations in the output fringe visibility, and consequently fading of the interferometric signal. Kersey et al.1 have reported the first demonstration of a polarisationinsensitive fibre-optic Michelson interferometer (FOMI) based on a birefringence compensation technique using a Faraday rotator mirror (FRM) in the final end of each arm of the interferometer.
Erbium-Doped Fibre as a Sensitive Element of the Cryogenic Temperature Sensor
Authors: Dianov E.M. , Kurkov A.S. , Medvedkov O.I. , Vasiliev S.A. , Baykin D. , Bender S. , Koretsky A.
Published: February 2023

Fibre-optic temperature sensors for the cryogenic temperature range can be efficiently used for the control over low temperature superconductor devices. Temperature monitoring of such devices is necessary to avoid its failure. We propose a new type of fibre-optic cryogenic temperature sensor. Its operation principle consists in measuring changes in optical losses of erbium-doped fibres, which occur owing to narrowing of the absorption spectrum of Er3+ ions with decreasing temperature.
Ultrashort-Pulse Lasers: Their Coming of Age
Authors: Sibbett Wilson
Published: February 2023

Although ultrashort-pulse lasers have been around since the first demonstration of the modelocking technique in the mid-1960s, the practicality of the more versatile versions of such lasers has tended to be the main limitation to their applicability. The availability in research years of solid-state broad-bandwidth vibronic gain media has also enlarged greatly the scientific and technological potential of modelocked lasers that are compatible with the femtosecond time domain. This latter situation not only opens up exciting possibilities for the development of sources of optical pulses towards the single-cycle, but the addition of appropriate amplification schemes also means that access can now be gained into a fascinating new world relating to the interaction of ultrahigh-intensity light pulses with matter.
Photonic Band Gaps
Authors: Shepherd T J
Published: February 2023

Photonic band gaps are ranges of frequency within which electromagnetic propagation is completely forbidden. They are present in certain materials which possess a periodicity of permittivity at the wavelength scale. Materials with these extreme properties are not known to occur naturally, and. at the optical wavelength scale, require fabrication methods at the current limits of technological feasibility. Such a photonic crystal provides a lossless barrier to propagation, and can suppress the emission of a photon by a decaying atom if the frequency of the emitted photon lies within the gap. A preferred propagation route, or mode, can be specified by designed defects within the photonic crystal; thus it is expected that I photonic crystals can provide a means whereby spontaneous emission is controlled in active media, and that all the spontaneously emitted light enters a single mode, resulting in an ideal zero-threshold laser. More generally, the photonic density of states is altered in these materials, and spontaneous emission can be enhanced or suppressed, as required. Other applications include novel all-angle reflectors, narrow-band filters, resonators, waveguides, and delay lines. When the fabrication problems for optical photonic crystals have been conquered, wavelength-scale periodic media will form an essential functions in a large range of optoelectronic systems.
Time-resolved interferometric technique and measurements of the nonlinear refractive index of laser materials
Authors: Milam D. , Weber M.
Published: February 2023

Intensity-dependent changes in the refractive index of optical materials associated with the propagation of intense laser beams cause self-focusing and beam breakup and a resultant loss of focusable energy. For long amplifier chains, such as used in Nd-glass fusion lasers, beam degradation originates in many transmissive elements. These include the lasing medium, lenses, windows, polarizer substrates, Faraday rotators, and nonlinear crystals. The beam degradation is proportional to n2/n(n − 1) for lenses, to n2/n for laser rods, windows, and rotators oriented normal to the beam, and to n2/n2 for laser disks at Brewster’s angle, where n and n2 are, respectively, the linear and nonlinear refractive indices. In all cases low n2 values are desirable. Accurate data on n2 is required for optimum staging of components in high-power laser systems.
Optical design aspects of the 10.6-µm laser data relay link transmitter/receiver
Authors: King William B. , Kinnard Roger W.
Published: February 2023

The Laser Data Relay Link (LDRL) program is directed toward applying optical communications to NASA’s wideband data transmission requirements through the 1980s. The first experimental deployment of LDRL-10.6 (using 10.6-µm wavelength) in space will be between a shuttle transmitting terminal and an elliptical orbit satellite or a ground receiving terminal. The subject of this paper is concerned with the optical design aspects of the laser transmitter and beacon receiver system for LDRL-10.6 space shuttle experiment.
Range-gated active TV system tradeoffs
Authors: Rosell Frederick A.
Published: February 2023

Range-gated TV cameras used in conjunction with pulsed scene irradiators offer distinct advantages over their passive counterparts for night-time viewing of terrestrial scenes at long range. Besides being independent of natural scene lighting, active TV cameras can be considered for use with very small fields of view without need of the large objective lenses required by passive systems. Since any camera f-number increases with viewfield decrease may be offset by increase in scene irradiation if source and sensor viewfields are matched.
Design of illumination systems for two-beam laser fusion experiments
Authors: Glass Alexander J. , Goodwin Edmund J. , Trenholme John B.
Published: February 2023

In any laser fusion scheme dependent on adiabatic implosion of the fusion target, it is of the utmost importance to illuminate the target uniformly over its entire surface area. A convenient method of providing illumination over the entire spherical surface from two beams was proposed by Thomas.1 In this method, a catadioptric system is employed, involving a fast (NA 0.7) lens and a pair of ellipsoidal mirrors of eccentricity ⅓. Subsequent refinements of this scheme have been developed at the Lawrence Livermore Laboratory.2
Data highway using optical fiber cable
Authors: Ueno Yoshito , Oogi Nagamitsu
Published: February 2023

Data highway systems using optical fiber cable are effective means by which multiplexed data signals can be sent between various terminals over a common cable. These systems have many advantages: independence from electromagnetic interference and electrical isolation from the ground; they are flexible in that new terminals can be added without extensive amounts of cable.
Delay distortion characteristics of optical fiber splices
Authors: Cherin Allen H.
Published: February 2023

Proper design of an optical communication system using optical fibers as the transmission medium requires a knowledge of the transmission characteristics of both the optical fibers and the splices used to join lengths of fibers together.
Computer simulation of isoplanatic effects on image phase conjugate laser adaptive control systems
Authors: Ehn Dennis , Wetzstein Hanns
Published: February 2023

Because of the distributed nature of the atmospheric turbulence in the imaging and propagation path of a laser beam correction system, it is expected that aberrations introduced by a lack of isoplanatism will limit the effectiveness of the image phase conjugate technique applied to compensate the effects of turbulence. This lack of isoplanatism arises because radiation from different parts of the extended imaged target experience different phase aberrations on their path to the common shared receiver/transmitter aperture. The results of the computer simulation presented show that these limits due to isoplanatism allow a very high degree of correction even with severe atmospheric turbulence. A very considerable increase in far-field irradiance is achieved by this adaptive correction technique, and the limit of achievable results is compared with the diffraction limit using a point source reference in the presence of the atmosphere. This diffraction limit is set by the performance of the wavefront measurement and control system. The simulation procedure used is as follows: The atmosphere is modeled by a discrete number of phase screens which are shown to give the same isoplanatic effects as a fully distributed atmosphere. Through these screens, radiation from several points over an extended region of the imaged object are propagated to the transmitter aperture. The incoherent addition of these and the resultant measurement by a wavefront sensor are simulated. The conjugate phase of the measurement is then applied to an outgoing spherical laser wave, and this wavefront is then propagated through the phase screens to its nominal focus. Both Strehl ratios and encircled energy are calculated as measures of the effectiveness of the technique. The same simulation procedure may be applied to evaluating the technique in the presence of thermal blooming, as well as atmospheric turbulence.
Glint tracking using adaptive optical techniques
Authors: Wisner G. R. , Angelbeck A. W. , Woody B. A. , Greiner A. F. , Freeman R. H. , Reynolds H. C.
Published: February 2023

Adaptive optical techniques have been employed to track target glint returns using two-axis steering and focus correction. Measurements were made on laboratory apparatus, operating at 10.6 µm. The apparatus consists of a low power CO2 laser, a 300-Hz bandwidth wavefront manipulator, focusing optics to form a far-field beam pattern, a moving glint (a small polished sphere), and an on-axis receiver that views target return. Adaptive control is implemented by tagging each correction mode with a high-frequency low-amplitude dither which is a small fraction of the available mode range. Classical hill-climbing servos are used to maximize glint return by nulling the dither component of each correction at a zero slope point corresponding to maximum target power.
Adaptive optics: closed loop estimation and predictive control considerations
Authors: Ogrodnik Robert F. , Asher Robert
Published: February 2023

Adaptive optical techniques involve the closed loop processes of wavefront error sensing and corrective control based on some performance criteria dictated by the intended application. Error sensing and corrective control procedures employed both in analytical and experimental adaptive optical studies to date involve generally direct techniques and fixed performance criteria. That is, current procedures employ wavefront compensatation control that is directly related to sensed errors (as in the case of interferometric phase measurement type systems) or directly derivable from sensed signal modulations (as in the case of amplitude modulated multidither type systems). Further, the controlling performance criteria are generally fixed. These approaches exclude considerations of the dynamic nature of the wavefront distortion processes which the system is attempting to compensate. Also, corrective trends successfully executed by the control process are neither identified nor employed during the continuously cycled corrective loop. This study will assess the merits of adding to the conventional adaptive optical convergence algorithm the sophistication of estimation and adaptive performance criteria. These features will be configured to sense and in real time predict the behavior and dynamic processes involved in wavefront distortion for the purposes of improved compensation performance, convergence responses, and stable criteria optimization. Details will be given regarding the behavior of convergence and error sensing algorithms that are based on estimation and predictive filtering theory. Figures of merit will be defined and examined to performance compare these adaptive algorithm approaches with conventional approaches. The degree of increased sophistication, modeling, and hardware implementation for these approaches will also be discussed and compared with conventional approaches.
Telecopier 200 facsimile device
Authors: Mrdjen Peter , Mason Peter , Howarth David E.
Published: February 2023

Xerox has been in the facsimile market since the early Sixties. The earliest Telecopier device was able to send a document over telephone lines with a resolution of about 100 lines/in. The transmission speed for a 8½ × 11-in. document was 6 min. Further development led to the appearance of the Telecopier 400 model which was able to transmit a document in 4 min or 6 min. This compact device transmitted at higher speed (4 min) with some loss of resolution. These devices use a conventional light source for scanning the document. The printing was done on photoresistive paper.
Computer controlled ground electrooptical systems for deep space operations
Authors: Schelonka Edward P.
Published: February 2023

Digitally controlled ground electrooptical systems have been designed such that all possible total system uncertainties are accounted for prior to track. The definition of total system here encompasses the satellite, earth, and station as a whole measured to common references. Considerations include utilizing stabilized oscillators to generate compensated Universal Time (UTC) thus reducing system time uncertainties to less than 2 μsec, reducing pointing uncertainties to less than 1 sec of arc with 21-bit encoders and knowledge of station geodetic location to within a small number of feet. Sensor biases and errors both static and dynamic are removed or modeled prior to track. Initially this is accomplished through a precise static (moving at sidereal rates) calibration of the mount to the celestial sphere. Data on several hundred stars are resident in the computer, and where specific stars are selected the system will continually point open loop to that reference as angular deviations are measured. With sufficient observations of a sampled distribution of known stars, the modeling constants are computed and the entire process repeated until angular deviations are zero. Slew measurements are made to determine dynamic constants. The system is then used to track known satellites and over-all system performance observed to insure that modeling is correct. A generalized block diagram is shown in Fig. 1.
Autonomous rendezvous and docking in synchronous orbit with a 10.6-μm ladar
Authors: Adelman Stephen , Weindling Frederik , Lowrey Dane O.
Published: February 2023

Recent studies conducted under NASA auspices have established that a pulsed CO2 ladar will offer a cost-effective and reliable solution to a family of space rendezvous and docking requirements. In addition, a system has been configured that is capable of performance unattainable by any other means.
Optical heterodyne radar (ladar) for precision missile tracking and guidance
Authors: Pratt Patrick D.
Published: February 2023

This paper presents the analysis and preliminary configurations of a 10.6-μm ladar using heterodyne detection. Low altitude supersonic antiship missiles pose a serious threat to U.S. Naval forces. Radars cannot accurately track them at short ranges due to multiple reflections from the ocean surface. Passive ir sensors exhibit contrast washout under certain conditions at low elevation angles. The ladar sensor provides a means of tracking ASMs at short ranges for precision fire control and for air-to-air missile guidance for head-on aircraft attack.
High-accuracy satellite laser ranging system
Authors: Byrns D. A. , Morford S. C.
Published: February 2023

The accuracy of satellite laser ranging systems has been improved from several meters to the present limit of 5-10 cm. Geodetic research in earthquake prediction, continental drift, polar motion, and gravitational-field modeling now requires range accuracies approaching 2 cm. The present hardware limitation has been the lack of a stable, short-pulse (<0.5-nsec), high-power (>1-GW) laser and matching receiver electronics. Such a system has been developed by GTE Sylvania for the Institut für Angewandte Geodäsie, FRG, and it is expected to become operational in mid 1976. This system is capable of ranging to all present and proposed geodetic satellites including GEOS, STARLETTE, and LAGEOS. Lunar ranging is also possible with modifications to system timing, software control, and data processing.
Picosecond-pulse fieldable frequency-doubled Nd:YAG laser system for ultraprecision ranging
Authors: Erickson Edward G. , Reynolds Richard S.
Published: February 2023

A unique picosecond-pulse Nd:YAG laser system has been developed for NASA for use in precision satellite ranging applications. It is the first frequency-doubled, picosecond-pulse Nd:YAG laser designed and packaged for stable operation in a field environment. This system emits an adjustable 100-1000-psec duration pulse containing 0.33 J at 532 nm or 0.50 J at 1064 nm. The pulse repetition rate is variable from 1.0 pps to 5.0 pps, and the pulse-to-pulse amplitude stability is ±5%. The output beam diameter is 3.6 cm, and the 85% full width divergence is 75 μrad. These performance characteristics are maintained for altitudes between sea level and 15,000 ft, temperatures between 40°F and 125°F, and a relative humidity up to 50%. The laser system also maintains performance in the vibration environment of a mobile electronic van. The basic design concept of this system is the regenerative amplification of a single mode-locked pulse from a cw pumped mode-locked Nd:YAG laser.
Image recording and display by embossable surface-relief structures
Authors: Engelbrecht R. S. , Gale M. T. , Knop K.
Published: February 2023

High-density information recording and replication using surface-relief structures is a well established process in phonograph record and video disk production. In this talk, we describe a promising new development—the recording of two-dimensional black/white and color images by surface-relief phase gratings. These can be replicated rapidly and inexpensively by hot embossing into clear thermoplastic sheets and are well suited for information dissemination in a compact format, e.g., microfiche. Unlike holographically encoded surface-relief images,1,2 they can be displayed with 100% efficiency in conventional optical projectors designed for photographic transparencies. Unlike photographic materials, however, they absorb no light and hence are free from overheating and color fading problems.
Liquid crystal artwork generator
Authors: Heinz Robert A. , Klaiber Robert J. , Oehrle Robert C.
Published: February 2023

This paper describes a highly responsive on-line approach to the production of complex photomasks. The pattern is generated on a refreshable display element (master) from which larger copies are projection printed. By using a refreshable master, the pattern information can be stored on computer tape, and all handling and storage of glass masters are eliminated.
Microfilm by laser transfer printing
Authors: Jacobs J. T. , Schreiber D. , Crooks W. , Weiche W. J.
Published: February 2023

Laser transfer printing of high resolution microfilm has been achieved. Volatile dyes were transferred from a Mylar substrate into a plastic receiver substrate. The carrier and receiver were held in contact by a simple vacuum chuck. The 70-mW He-Ne laser beam was focused onto the carrier, where it was absorbed, heating the dye and causing it to vaporize. The vapor condensed on and diffused into the plastic receiver substrate.
Uncertainties in particle size distributions measured with ratio-type single particle counters
Authors: Hirleman E. D. , Wittig S. L. K.
Published: February 2023

Analysis of the light scattered by individual particles passing through a focused laser beam has recently become a common technique for characterizing air pollution aerosols. Early optical particulate analyzers utilized the light scattered in a single field of view to classify particles by size, but were hampered by relatively low resolution. This was due to effects of the index of refraction on the functional dependence of the scattered intensity on particle diameters1 and to variations in incident light intensity within the sensitive volume, which is Gaussian for laser beams.
Damage resistance of holographic and ruled gratings used as laser wavelength-tuning elements
Authors: Gill Dennis H. , Newnam Brian E.
Published: February 2023

Gratings are frequently used in dye-laser cavities as wavelength-tuning elements. These gratings usually have the lowest damage threshold of any component in the system and thus determine or limit the maximum energy output available from the laser. It is therefore important to understand the damage characteristics of gratings and how they can be improved.
Development of waveguide CO2 lasers for a space communications transceiver
Authors: Johnston T. F. , Kolb W. P. , Ramsay I. A. , Romero C.
Published: February 2023

Sealed-off waveguide CO2 lasers1,2 for use as a local oscillator (LOL) and transmitter (TXL) in a space communications transceiver have been designed, fabricated, and tested. The waveguide laser design approach results in very small, lightweight, rugged devices and also achieves the wide frequency tuning3 required in the LOL because of the Doppler shift of the received signal.
Stress distribution measurement in oscillating quartz crystals with a laser probe
Authors: Yasuda Ichiji , Yamagata Sekiji
Published: February 2023

A quantitative dynamic stress measuring method in oscillating quartz crystals by means of optical beam modulation is reported. The principle of the measurement is as follows: The oscillating quartz crystal is placed between crossed polarizers. The modulated light intensity is expressed by ΔI/I = Δδ-sinδ/2 sin2(δ/2), where I is the de component and ΔI is the accomponent of the modulated light intensity, respectively.
Diagnostics of high-energy laser cavities using holographic techniques
Authors: Trolinger J. , Simpson G.
Published: February 2023

A holography system has been developed for diagnostics of high-energy laser cavities, flow visualization, and the study of combustion processes. The basic elements of the system include a pulsed ruby laser, the output of which is split at beam splitter. Both beams are then spatially filtered and collimated, one serving as an object beam while the other acts as a reference wave. The resulting hologram can be used to produce almost all common forms of flow visualization.
TIR acoustooptic surface wave modulator
Authors: Kramer C. J. , Araghi M. N. , Das P.
Published: February 2023

Until now, the majority of the acoustooptic modulators employed the interaction of light with bulk ultrasonic waves in solids and liquids. As a demonstration and test of the utility of surface acoustic waves (SAW) for light modulation applications, the high diffraction efficiency achieved with a novel side-entry laser probing technique1,2 was utilized to fabricate a number of elastooptic devices. These included a modulator utilized in a TV communication system and a convolver for a signal processing system.3
Plastic focusing fiber for imaging applications
Authors: Iga K. , Yamamoto N. , Matsuura Y.
Published: February 2023

Thus far, glass has been investigated as a focusing fiber material, but there remain the problems of flexibility and cost if a large diameter is necessary as in the case of imaging.1 On the other hand, plastic materials may be of equivalent quality2 but are more economical, flexible, and have the possibility of low chromatic aberration.3
Nitrogen laser using discrete ceramic capacitors in a Blumlein-type circuit
Authors: Sam C. L. , Kyros T. , Seymour R. J.
Published: February 2023

The incorporation of discrete ceramic capacitors into a Blumlein-type circuit in a N2 laser was first introduced by Nagata and Kimura.1 This design has the advantage of allowing for a large energy storage capacity in a fast current discharge circuit. We have developed an improved version of such a nitrogen laser system. Figure 1 shows a double-decker type laser head where two rows of capacitors, one above the other, are utilized on each side of the laser channel. Both the single-deck and the double-decker type laser heads have been built. An EG&G grounded-grid thyratron is used as the switch. By tightly coupling the thyratron to one electrode and locating it an equal distance from both ends of the electrodes, a uniform glow discharge is obtained. Since the excitation in this case is not the traveling-wave type, the pulsewidth is 7.5 nsec as compared with the 2-4 nsec obtained from the usual Blumlein design.2 Our laser configuration allows us to set up a cavity with a total reflector at one end and a partially reflecting mirror at the other end. An increase in output power and a decrease in beam divergence are observed in this situation as compared with the case when no output coupler is used. This is in contrast to the case of traveling-wave excitation when most of the energy is derived from one end of the laser.2 A plot of efficiency (output energy/input energy per pulse) vs the applied voltage for output mirrors with different reflectivities is shown in Fig. 2 for a single-deck laser. This laser has a gap of 1.5 cm between the electrodes and a total capacitance of 25 nF. When a 4% output coupler is used, this laser has a peak power of 175 kW at 15 kV and 130-Torr N2 pressure when operating at 20 pulses/sec. The half-angle divergence is 0.7 × 3.5 mrad. These data can be extended to the double-decker laser, which has comparable efficiencies but twice the energy storage capacity. Peak power of 500 kW has been obtained from a double-decker laser with 3-cm gap spacing. The combined features of high power, long pulsewideth, and low divergence make this type of N2 laser a highly efficient pump for dye lasers. It is also stable, compact, durable, and simple to build. Work is under way to increase the pulse repetition rate. Further technical details will be presented, and limits on the performance and reliability of this type of N2 laser will be discussed.
Efficient high-power CH3F 496-μm laser systems
Authors: Plant T. K. , DeTemple T. A.
Published: February 2023

Many different configurations, both cw and pulsed, have been reported for a 496-μm CH3F laser optically pumped with a CO2 laser; however, none as yet has both the high efficiency and good beam quality required for plasma diagnostics applications.1-4 Simple superradiant geometries using multimode TEA CO2 lasers have produced peak powers > 1 MW, but in pulses with subnanosecond structure.2 Complicated cavity geometries have yielded smooth pulses but only at lower powers, and both methods have a photon conversion efficiency (number of 496-μm quanta/number of CO2 quanta absorbed) of only ~5%.
Low-power low-cost blue lasers
Authors: Hawkins J. D. , Shull W. A. , Reynolds T. B. , Dowley M. W.
Published: February 2023

The He-Cd laser has been in commercial development for about 5 years. Compared with the established He–Ne laser, cadmium laser technology is comparatively young. There are numerous similarities between the two laser types, but there are also substantial differences.
Remote air pollution monitoring system using a tunable 1.4–4.0-μm infrared source
Authors: Baumgartner R. , Warshaw S. , Wolfe D. , Byer R. L.
Published: February 2023

We are completing the construction and testing of a remote air pollution detection system that utilizes a 1.4–4-μm tunable LiNbO3 parametric oscillator source. The Nd.YAG pumped parametric oscillator operates under computer control at greater than 20% energy conversion efficiency. Bandwidths using grating, etalon line narrowing elements are less than 0.1 cm−1.
DFVLR airborne lidar system
Authors: Werner C. , Michl W.
Published: February 2023

The DFVLR-Lidar-System VI is made for airborne use to measure aerosol mass concentration over greater areas than it is possible from ground stations. It consists of a Nd-glass laser as a transmitter and a parabolic mirror as a receiver. Technical data are given in Table I.
Generation of subnanosecond CO2 laser pulses by electrooptical modulation
Authors: McLellan E. J. , Figueira J. F.
Published: February 2023

For certain applications of CO2 lasers to inertial confinement fusion experiments, the availability of subnanosecond laser pulses is of importance. In this paper we describe a method of reliably generating 325-psec CO2 laser pulses using an extension of earlier work by Smith and Davis.1 This system is currently being installed in the LASL single beam prototype laser.
Laser scanning system for roller bearing quality assurance
Authors: Cheng Charles K.
Published: February 2023

This paper describes the design and engineering of an automatic inspection system for detecting minute flaws during the manufacture of precision roller bearings used in aircraft. The various types of flaws to be detected are scratches, pits, voids in seams, rust, and other surface flaws whose sizes are usually in the order of 25 μm. Visual inspection is impractical and subject to human errors.
Simultaneous measurement of humidity and temperature based on fiber-tip microcantilever cascaded with fiber Bragg grating
Authors: Liu Dan , Cai Zhihao , Li Bozhe , Zou Mengqiang , Zhang Lichao , Hua Yunzhi , Mai Junhao , Zhao Cong , Liao Changrui , He Jun , Weng Xiaoyu , Liu Liwei , Qu Junle , Wang Yiping
Published: February 2023

We demonstrated a hybrid sensor of fiber Bragg grating (FBG) and Fabry-Perot interferometer (FPI) based on fiber-tip microcantilever for simultaneous measurement of temperature and humidity. The FPI was developed using femtosecond (fs) laser-induced two-photon polymerization to print the polymer microcantilever at the end of a single-mode fiber, achieving a humidity sensitivity of 0.348 nm/%RH (40% to 90%, when temperature = 25 °C ± 0.1 °C), and a temperature sensitivity of -0.356 nm/°C (25 to 70 °C, when RH% = 40% ± 1%). The FBG was line-by-line inscribed in the fiber core by fs laser micromachining, with a temperature sensitivity of 0.012 nm/ °C (25 to 70 °C, when RH% = 40% ± 1%). As the shift of FBG-peak on the reflection spectra is only sensitive to temperature rather than humidity, the ambient temperature can be directly measured by the FBG. The output of FBG can also be utilized as temperature compensation for FPI-based humidity measurement. Thus, the measured result of relative humidity can be decoupled from the total shift of FPI-dip, achieving the simultaneous measurement of humidity and temperature. Gaining the advantages of high sensitivity, compact size, easy packaging, and dual parameter measurement, this all-fiber sensing probe is anticipated to be applied as the key component for various applications involving the simultaneous measurement of temperature and humidity.
Generation of high-dimensional caustic beams via phase holograms using angular spectral representation
Authors: Sun Zhuo , Hu Juntao , Wang Yishu , Ye Wenni , Qian Yixian , Li Xinzhong
Published: February 2023

Using angular spectral representation, we demonstrate a generalized approach for generating high-dimensional elliptic umbilic and hyperbolic umbilic caustics by phase holograms. The wavefronts of such umbilic beams are investigated via the diffraction catastrophe theory determined by the potential function, which depends on the state and control parameters. We find that the hyperbolic umbilic beams degenerate into classical Airy beams when the two control parameters are simultaneously equal to zero, and elliptic umbilic beams possess an intriguing autofocusing property. Numerical results demonstrate that such beams exhibit clear umbilics in 3D caustic, which link the two separated parts. The dynamical evolutions verify that they both possess prominent self-healing properties. Moreover, we demonstrate that hyperbolic umbilic beams follow along a curve trajectory during propagation. As the numerical calculation of diffraction integral is relatively complex, we have developed an effective approach for successfully generating such beams by using phase hologram represented by angular spectrum. Our experimental results are in good agreement with the simulations. Such beams with intriguing properties are likely to be applied in emerging fields such as particle manipulation and optical micromachining.
Theory of quantized photonic spin Hall effect in strained graphene under a sub-Tesla external magnetic field
Authors: Shu Yetao , Song Yifei , Wen Zhaoxin , Zhang Yong , Liu Shuoqing , Liu Jing , Luo Zhaoming
Published: February 2023

The quantized photonic spin Hall effect (PSHE) in the strained graphene-substrate system is predicted under a sub-Tesla external magnetic field, which is two orders of magnitude smaller than required to produce the quantized effect in the conventional graphene-substrate system. It is found that in-plane and transverse spin-dependent splittings in the PSHE, exhibit different quantized behaviors and are closely related to the reflection coefficients. Unlike the quantized PSHE in the conventional graphene-substrate system formed by the splitting of real Landau levels, the quantized PSHE in the strained graphene-substrate system is attributed to the splitting of pseudo-Landau levels caused by the pseudo-magnetic field and the lifting of valley degeneracy of the n ≠ 0 pseudo-Landau levels induced by the sub-Tesla external magnetic field. At the same time, the pseudo-Brewster angles of the system are also quantized with the change of Fermi energy. The sub-Tesla external magnetic field and the PSHE appear as quantized peak values near these angles. The giant quantized PSHE is expected to be used for direct optical measurements of the quantized conductivities and pseudo-Landau levels in the monolayer strained graphene.
Probabilistic shaping-based delta sigma modulation
Authors: Zhao Li , Xu Sicong , Wang Mingxu , Sang Bohan , Long Jianyu , Zhang Long , Zhou Wen , Wang Kaihui , Yu Jianjun
Published: February 2023

This Letter proposes a probabilistic shaping delta-sigma modulation technique. By performing delta-sigma modulation on the probability shaping signal at the transmitting end, under the same transmit power and the same net bit rate, the delta-sigma modulation signal based on probability shaping can obtain better anti-noise capability than the delta-sigma modulation signal only. Under the same information entropy conditions, the bit error rate performance of the PS-based 131072QAM signal modulated by delta-sigma modulation is better than that of the ordinary 65536QAM signal using the delta-sigma modulation scheme, and lower than that of soft decision–forward error correction (4 × 10−2).
Selectively gas-filled anti-resonant hollow-core fibers for broadband high-purity LP11 mode guidance
Authors: Jia Anqing , Hong Yifeng , Liu Qi , Sun Yizhi , Gao Shoufei , Sheng Yulin , Wang Yingying , Ding Wei
Published: February 2023

An anti-resonant hollow-core fiber capable of propagating the LP11 mode with high purity and over a wide wavelength range is proposed and demonstrated. The suppression of the fundamental mode relies on the resonant coupling with specific gas selectively filled into the cladding tubes. After a length of 2.7 m, the fabricated fiber shows a mode extinction ratio of over 40 dB at 1550 nm and above 30 dB in a wavelength range of 150 nm. The loss of the LP11 mode is measured to be 2.46 dB/m at 1550 nm. We discuss the potential application of such fibers in high-fidelity high-dimensional quantum state transmission.
Twisted Partially Coherent Full Poincaré Beams
Authors: Zhu Shijun , Huang Yan , Yuan Shicheng , kong zhuoran , Tian Cong , Cai Yangjian , Li Zhen-hua
Published: February 2023

Full Poincaré (FP) beams that present all possible states of fully polarized light across their transverse section have received great attention in recent years. However, compared with huge successful design in coherent case, attempts in partial coherent case seem to encounter considerable challenges. It is generally believed that the difficulty of polarization change upon propagation induced by correlation seems inevitable. With the help of a new degree of freedom–twist phase, the correlation-induced polarization change is successfully eliminated. A new class of propagation-invariant twisted partially coherent FP beams are derived under specific parameter conditions to ensure complete polarization. Similar to coherent FP beams, all the polarization states of the beams are retained and covers the entire surface of the Poincaré sphere, and the propagation corresponds to a rigid rotation of the sphere. Besides, the twist phase can also be used to modulate the rigid rotation speed of the Poincaré sphere and the far-field beam spot size. The result paves the way for the design of FP beams and fully polarized vector beams in partially coherent domain and opens up new opportunities for applications such as scattering, polarization measurement, and optical sensing.
Semi-immersive photonic hook and optical trapping along an air-liquid interface
Authors: Yue Liyang , Yan Bing , Wang Zengbo , Minin Oleg , Minin Igor
Published: February 2023

In this paper, we demonstrate a novel semi-immersive photonic hook, which is a bent light focus by a dielectric micro-cylinder partially immersed at the edge of a thin liquid film. It only propagates along the air-liquid interface (ALI) and possesses a formation mechanism without material processing for micro-particle and modulation of light irradiation. The existence of ALI at the shadow end of the micro-cylinder and contrasts of refractive indexes over there cause this phenomenon at the specific depths of liquid films. Compared to the previously discovered photonic hooks, its unique setup can generate an optical force field in the ALI region to realise optical trapping for applications in microfluidics, micro/nano-engineering, and biomedical research. The morphology of this photonic hook and its optical trapping forces to micro-object varying locations were analysed to study the formation and feasibility of optical trapping along ALI in this approach.
I do not want to set my own price! Indirect effects of emotions and moderation effects of skepticism explain reduced use intentions towards participative pricing models
Authors: Wittstock-Lang Regina , Bekk Magdalena , Spörrle Matthias
Published: February 2023

Participative pricing models (i.e., auction, reverse auction, pay-what-you-want) have grown in importance compared to classical, non-participative pricing models (i.e., fixed price, discount). This study examined (1) relative use intentions regarding different (non-) participative pricing models, (2) the emotional responses triggered by the pricing models and influencing consumers’ use intentions, and (3) the moderating role of individual skepticism in this context. A between-subjects experiment (N = 505) with five groups, manipulating participative (auction, reverse auction, and pay-what-you-want) and non-participative (fixed price and discount) pricing models, detected reduced use intentions towards participative compared to non-participative pricing models. Even though participative pricing models induced higher levels of positive as well as negative emotions, the effects via positive emotions (promoting use intentions) were weaker than the effects via negative emotions (mitigating use intentions). Skepticism towards participative pricing models enhanced negative emotions and decreased positive emotions. Practical applications should rely on enhancing positive emotions while simultaneously reducing negative emotions, as they exert independent effects. Skepticism of potential users should be mitigated in the early stages of the customer relationship, e.g., via trustworthiness triggers.
Cultured rat aortic vascular smooth muscle cells do not express a functional TRPV1
Authors: Blažević Tina , Ciotu Cosmin I. , Gold-Binder Markus , Heiss Elke H. , Fischer Michael J. M. , Dirsch Verena M.
Published: February 2023

We showed previously that capsaicin, an active compound of chili peppers, can inhibit platelet-derived growth factor-induced proliferation in primary rat vascular smooth muscle cells (VSMCs). The inhibition of BrdU incorporation by capsaicin in these cells was revoked by BCTC, which might be explained by a role of TRPV1 in VSMCs proliferation. To further pursue the hypothesis of a TRPV1-dependent effect of capsaicin, we investigated TRPV1 expression and function. Commercially available antibodies against two different TRPV1 epitopes (N-terminus and C-terminus) were rendered invalid in detecting TRPV1, as shown: i) in western blot experiments using control lysates of TRPV1-expressing (PC-12 and hTRPV1 transfected HEK293T) and TRPV1-downregulated (CRISPR/Cas gene edited A10) cells, and ii) by substantial differences in staining patterns between the applied antibodies using fluorescence confocal microscopy. The TRPV1 agonists capsaicin, resiniferatoxin, piperine and evodiamine did not increase intracellular calcium levels in primary VSMCs and in A10 cells. Using RT qPCR, we could detect a rather low TRPV1 expression in VSMCs at the mRNA level (Cp value around 30), after validating the primer pair in NGF-stimulated PC-12 cells. We conclude that rat vascular smooth muscle cells do not possess canonical TRPV1 channel activity, which could explain the observed antiproliferative effect of capsaicin.
Clinic-based SAMBA-II vs centralized laboratory viral load assays among HIV-1 infected children, adolescents and young adults in rural Zimbabwe: A randomized controlled trial
Authors: Kouamou Vinie , Machekano Rhoderick , Mapangisana Tichaona , Maposhere Caroline , Mutetwa Reggie , Manasa Justen , Shamu Tinei , McCarty Kathy , Munyati Shungu , Mutsvangwa Junior , Bogoshi Mampedi , Israelski Dennis , Katzenstein David
Published: February 2023

Background

In Zimbabwe, children, adolescents and young adults living with HIV (CALWH) who are on public health antiretroviral therapy (ART) have inadequate viral load (VL) suppression. We assessed whether a clinic-based VL monitoring could decrease 12-month virologic failure rates among these CALWH.

Methods

The study was registered on ClinicalTrials.gov: NCT03986099. CALWH in care at Chidamoyo Christian Hospital (CCH) and 8 rural outreach sites (ROS) on long-term community-based ART were randomized (1:1) to 6 monthly VL monitoring by COBAS®Ampliprep®/Taqman48® HIV-1 at the provincial referral laboratory (PRL) as per standard of care (SOC) or by the clinic-based SAMBA II assay, Diagnostics for the Real World, at CCH. VL suppression, turn-around-time (TAT) for VL results, drug switching and drug resistance in second-line failure were assessed at 12 months.

Results

Of 390 CALWH enrolled 347 (89%) completed 12 months follow-up. Median (IQR) age and ART duration were 14.1 (9.7–18.2) and 6.4 (3.7–7.9) years, respectively. Over half (57%) of the participants were female. At enrolment, 78 (20%) had VL ≥1,000 copies/ml and VL suppression of 80% was unchanged after 12 months, with no significant difference between the SOC (81%) and the clinic-based (80%) arms (p = 0.528). Median (IQR) months to confirmatory VL result at CCH vs PRL was 4.0 (2.1–4.4) vs 4.5 (3.5–6.3) respectively; p = 0.027 at 12 months. Drug switching was documented among 26/347 (7%) participants with no difference between the median (IQR) time to switch in SOC vs clinic-based arms (5.1 (3.9–10.0) months vs 4.4 (2.5–8.4) respectively; p = 0.569). Out of 24 confirmed second-line failures, only 4/19 (21%) had protease inhibitor resistance.

Conclusion

In rural Zimbabwe, the clinic-based SAMBA II assay was able to provide confirmatory VL results faster than the SOC VL assay at the PRL. However, this rapid TAT did not allow for a more efficient drug switch among these CALWH.
Visualizing increased uptake of [18F]FDG and [18F]FTHA in kidneys from obese high-fat diet fed C57BL/6J mice using PET/CT ex vivo
Authors: Nyrén Rakel , Scherman Henrik , Axelsson Jan , Chang Chuchun L. , Olivecrona Gunilla , Ericsson Madelene
Published: February 2023

It is known that high-fat diet (HFD) and/or diabetes may influence substrate preferences and energy demands in the heart preceding diabetic cardiomyopathy. They may also induce structural glomerular changes causing diabetic nephropathy. PET/CT has been utilized to examine uptake of energy substrates, and to study metabolic changes or shifts before onset of metabolic disorders. However, conventional PET/CT scanning of organs with relatively low uptake, such as the kidney, in small animals in vivo may render technical difficulties. To address this issue, we developed a PET/CT ex vivo protocol with radiolabeled glucose and fatty acid analouges, [18F]FDG and [18F]FTHA,to study substrate uptake in mouse kidneys. We also aimed to detect a possible energy substrate shift before onset of diabetic nephropathy. The ex vivo protocol reduced interfering background as well as interindividual variances. We found increased uptake of [18F]FDG and [18F]FTHA in kidneys after HFD, compared to kidneys from young mice on standard chow. Levels of kidney triglycerides also increased on HFD. Lipoprotein lipase (LPL) activity, the enzyme responsible for release of fatty acids from circulating lipoproteins, is normally increased in postprandial mice kidneys. After long-term HFD, we found that LPL activity was suppressed, and could therefore not explain the increased levels of stored triglycerides. Suppressed LPL activity was associated with increased expression of angiopoietin-like protein4, an inhibitor of LPL. HFD did not alter the transcriptional control of some common glucose and fatty acid transporters that may mediate uptake of [18F]FDG and [18F]FTHA. Performing PET/CT ex vivo reduced interfering background and interindividual variances. Obesity and insulin resistance induced by HFD increased the uptake of [18F]FDG and [18F]FTHA and triglyceride accumulation in mouse kidneys. Increased levels of [18F]FDG and [18F]FTHA in obese insulin resistant mice could be used clinically as an indicator of poor metabolic control, and a complementary test for incipient diabetic nephropathy.