bluuebunny/crossref_metadata_2025 huggingface dataset:
Thinking About Tomorrow
Authors: Leevers Hilary
Published: February 2023

EngineeringUK CEO Dr Hilary Leeversmarks the 10th annual Tomorrow’s Engineers Week with a plea for the whole community to show the next generation the breadth of careers available in engineering and technology
In a Class of their Own
Authors: Buck David
Published: February 2023

What is the difference between Class I and Class II power supplies?
Flexing Their Wings
Authors: Eden Paul E
Published: February 2023

Customers appreciate the Global 6000's smooth ride, but it wasn't until Bombardier conducted a series of innovative tests that there was quantifiable data to support their claims
One Giant Leap for Mankind
Authors: Coppinger Rob
Published: February 2023

The space launch system is the largest rocket ever built, and it';s currently being tested using infrastructure on the same sclae as its massive structure before it sends astronauts to the moon
Evaluation of Digital Rural Development from the Perspective of Rural Revitalization – Take Zhejiang Province as an Example
Authors: Zhang Songyan , Wu Simin
Published: February 2023

The construction of the digital village is a combination of the concept of digital economy and the strategy of rural revitalization, which requires a correct understanding and scientific evaluation. Taking Zhejiang Province as the research object, based on the actual situation and the connotation of digital villages, a digital village indicator system was constructed from the two dimensions of digital village development capacity and development effectiveness, and the relative entropy TOPSIS method was used to analyze the digital villages in Zhejiang Province from 2016 to 2019. Compare and evaluate the development level. The results show that the development of digital villages in Zhejiang Province has achieved remarkable results, and the development level of digital villages has been improved year by year. Among them, the index scores of industry digitalization, governance digitalization, service digitalization, digital life, agricultural production, farmers’ prosperity, and rural prosperity have achieved stable or rapid growth. The close value of TOPSIS is increasing year by year. Finally, it puts forward countermeasures and suggestions to promote the development of digital villages across the country.
How the Covid-19 Pandemic Affects Sustainable Development: The Impact on the Social, Economic and Energy Parameters of Sustainable Development
Authors: Martynets Viktoriya , Opanasiuk Yuliia , Matvieieva Yuliia
Published: February 2023

The Covid-19 pandemic has been a challenge for all countries of the world. Although the most negative impact was on public health, the pandemic also caused damage to the economic, social and energy sectors.

The research puts forward a hypothesis about the differentiation of countries due to the impact of the Covid-19 pandemic on the economic, social and energy parameters of sustainable development. A negative impact on indicators such as GDP, the number of unemployed, electricity generation was identified.

The following methods were used in the article to analyze the impact of the Covid-19 pandemic on the economic, social and energy parameters of sustainable development: systems analysis, deductive approach, regression and correlation analysis and extrapolation.

Theoretical and empirical research show that the economies of countries were not ready for the negative transformation processes caused by the quarantine restrictions. The after-effects of the pandemic will manifest themselves for the long period without concerted action of governments, businesses and the international community. It will negatively affect the social and economic development of countries and undermine the progress towards achieving the sustainable development goals until 2030.

This article will be useful for researchers, political elite and international organizations while developing the anti-crisis programs and programs for the social and economic development of the countries.
The effects of micronutrient-enriched media on the efficacy of Bacillus subtilis as biological control agent against Meloidogyne incognita
Authors: Adiwena Muh. , Murtilaksono Aditya , Egra Saat , Hoesain Mohammad , Asyiah Iis Nur , Pradana Ankardiansyah Pandu , Izatika Zidna Nurul
Published: February 2023

The root-knot nematodes Meloidogyne incognita poses a serious threat to horticultural food and plantation crops. One of the effective and efficient measures to overcome this nematode is using bacteria as a biological control agent. This study aimed to test the effectiveness of Bacillus subtilis bacteria grown on media with additional micronutrients as a biological control agent for M. incognita. The test was carried out by growing bacteria in 100 mL of nutrient broth (NB) added with FeCl2, MnCl2, and CuCl2. Each type of micronutrient was administered at concentrations of 35 ppm, 40 ppm, 45 ppm, 50 ppm, and 55 ppm. As a control, NB media was used without the addition of micronutrients. The test results showed that the best performances on bacterial growth were 55 ppm MnCl2, 45 ppm MnCl2, 40 ppm MnCl2, 40 ppm CuCl2, 50 ppm MnCl2, and 35 ppm MnCl2. These six treatments were then used in an antagonism test. A total of 150 J2 M. incognita in 4 mL of suspension was put into a petri dish with a diameter of 5 cm. After that, 1 mL of each bacterial suspension was put into a petri dish following the treatment. The mortality rate of M. incognita in each treatment was 77.5% in 55 ppm MnCl2, 74.5% in 45 ppm MnCl2, 77.25% in 40 ppm MnCl2, 73.25% in 40 ppm CuCl2, 78.75% in 50 ppm MnCl2, 79% in 35 ppm MnCl2, and 53.25% in control. The same six treatments were also used to measure the chemotaxis index of M. incognita on tomato roots. Tomato seeds of the Tantyna variety were soaked for 60 minutes in a bacterial suspension grown on micronutrient-enriched media. After seven days, the tomato seed roots were removed and placed in 5 mL 20% Pluronic F-127 Gel which had been infested with 100 J2 M. incognita. After 6 hours, the number of nematodes approaching the roots was observed. The chemotaxis index in the treatments ranged from 16% to 24%, while that in the control was 33%. This study corroborates that the addition of micronutrients MnCl2 and CuCl2 to the growth medium of B. subtilis can increase antagonistic activity against M. incognita and suppress its chemotaxis response in tomato roots soaked in the bacterial suspension.
Karyotyping of green, yellow and red matoa (Pometia pinnata J.R.Forst. & G.Forst.) from Central Java, Indonesia
Authors: YUNIASTUTI ENDANG , MASAILLA ANANDA PUTRI DEWANTARI , NANDARIYAH NANDARIYAH , RAHMAH NAILU
Published: February 2023

Abstract. Yuniastuti E, Masailla APD, Nandariyah, Rahmah N. 2023. Karyotyping of green, yellow and red matoa (Pometia pinnata J.R.Forst. & G.Forst.) from Central Java, Indonesia. Biodiversitas 24: 40-46. Matoa (Pometia pinnata J.R.Forst. & G.Forst.) belongs to Sapindaceae family and is widely distributed naturally in Indonesia. However, research on matoa plants,especially for the genetic aspect is poorly reported. Genetic information, through chromosome analysis can be helpful in plant breeding programs. This study aimed to analyze karyotype of chromosomes green, yellow and red matoa collected from Central Java, Indonesia. Chromosome analysis in this study used the squash preparation method. This research was the first karyotyping of matoa using 3 types based on exocarp colors, namely green, yellow and red skin matoa. Each type of matoa was repeated 4 times. The results showed that three types of matoa skin colors have the same number of chromosomes, namely 2n=2x=22 with each chromosome size of green, yellow, and red matoa are 1.070±0.251 ?m, 1.025±0.281 ?m, 006±0.252 ?m, respectively and all of matoa have a metacentric chromosome’s form. The karyotype formula for each type of matoa is 2n=2x=22=11m.
Short Communication: Analysis of rhizome color and phytochemical content of 10 accessions of Curcuma zanthorrhiza Roxb. in Jambi, Indonesia
Authors: MINARNI MINARNI , ASYHAR RAYANDRA , JULIANA DARA , YUDHA YOSHUA SHANDY , NURCHOLIS WARAS
Published: February 2023

Abstract. Minarni M, Asyhar R, Juliana D, Yudha YS, Nurcholis W. 2023. Short Communication: Analysis of rhizome color and phytochemical content of 10 accessions of Curcuma zanthorrhiza Roxb. in Jambi, Indonesia. Biodiversitas 24: 149-155. Plants are a source of secondary metabolites that have various biological functions and are beneficial for humans, particularly in the health sector. One such beneficial herbal plant, temulawak (Curcuma zanthorrhiza Roxb.), a member of the genus Curcuma L. in the Zingiberaceae family, is widely known as Javanese turmeric. C. zanthorrhiza is a potential source of drugs in the field of pharmacology. One part of temulawak that has an important role is the rhizome, commonly used in the formulation of traditional herbal medicines. There are many pharmacologically active components contained in the C. zanthorrhiza rhizome. Thus, this plant, found in many parts of Indonesia, such as Jambi and Sumatra, is worthy of detailed pharmacological investigation. The study reported in this paper aimed to determine the potential content of secondary metabolites of alkaloids, flavonoids, saponins, tannins/phenolics, and triterpenoids/steroids in 10 accessions of temulawak rhizomes in Jambi. The phytochemical content analysis in temulawak was carried out by qualitative phytochemical screening using dye reagents. Multivariate cluster analysis was carried out to determine the relationships between the 10 accessions based on similarities in the color and phytochemical content of their rhizomes. Generally, the screening results showed that the rhizomes of the 10 C. zanthorrhiza accessions contained the same intensities of alkaloids (dragendof, mayer and wagner), flavonoids, tannins/phenolics (+++) and steroid compounds (++). On the other hand, saponin and triterpenoid were not detected in the tests of rhizomes of the 10 accessions (-). The clustering analysis of the results divided the 10 local temulawak accessions into three clusters. Cluster-1 consisted of two accessions (JM and JBB), cluster-2 consisted of three accessions (JT, JPB, and JBS), and cluster-3 consisted of five accessions (JSS, JJ, JB, JBE, and JG).
Impact of physicochemical parameters of water on the biodiversity of the invertebrate fauna from Echatt Lake, Northeast Algeria
Authors: MOUNIRA HOUMANI , FATIHA BENDALI-SAOUDI , NOUREDDINE SOLTANI
Published: February 2023

Abstract. Mounira H, Fatiha BS, Noureddine S. 2023. Impact of physicochemical parameters of water on the biodiversity of the invertebrate fauna from Echatt Lake (Northeast Algeria). Biodiversitas 24: 258-268. Algeria is a case study of biodiversity ignorance. To date, there are neither complete inventories for any taxa nor atlas across the country! Yet, Algeria is of great importance for global biodiversity. The coastal area of Algeria is part of the global biodiversity hotspot which is the Mediterranean perimeter and has several regional red spots of biodiversity. Biodiversity provides raw material resources necessary for living beings' survival and maintaining atmospheric quality, climate regulation, water quality, and soil fertility. In addition, macrobenthic fauna is an important provider of aquatic ecosystems. The present study aimed to determine the biodiversity of the invertebrate community from Echatt Lake (Northeast Algeria) located in a protected area classified by Ramsar in 1983, and to evaluate the impact of anthropogenic activities using water physicochemical parameters on their structure and function. Samples were collected monthly over one year (January 2019-December 2019) at four selected stations, and 2,861 specimens were collected. The identified species (16 species) belong to 9 families: Naucoridae, Hydrophilidae, Notonectidae, Pleidae, Corexidae, Eylaidae, Pionidae, Daphniidae, and Copepoda. Seven physicochemical parameters (temperature, hydrogen potential, electrical conductivity, hydrometric title, alkalimetric title, complete alkalimetric titer, and turbidity) of the water were also determined in each station to evaluate their influence on the abundance and distribution of the invertebrate fauna. The pH and the apparent turbidity influence the invertebrate fauna, while the richness was relatively low at stations 2 and 4, located near anthropogenic sources of pollution. The data obtained permitted us to evaluate the possible impact of anthropogenic activities on the biodiversity of invertebrates.
The local knowledge and potential of suweg (Amorphophallus paeoniifolius) in the Citanduy and Cimanuk watersheds of West Java, Indonesia
Authors: MUTAQIN ASEP ZAINAL , ISKANDAR JOHAN , IRAWAN BUDI , SURYANA SURYANA , KURNIADIE DENNY , NURZAMAN MOHAMAD , SHANIDA SYA SYA
Published: February 2023

Abstract. Mutaqin AZ, Iskandar J, Irawan B, Suryana, Kurnadie D, Nurzaman M, Shanida SS. 2023. The local knowledge and potential of suweg (Amorphophallus paeoniifolius) in the Citanduy and Cimanuk watersheds of West Java, Indonesia. Biodiversitas 24: 370-378. The Indonesian archipelago is rich in natural resources and ethnic diversity. Each ethnic group interacts with the surrounding environment in ways that often differ. Interaction with the environment creates local knowledge that is complex in terms of language, practical understanding, beliefs, and social interaction. One useful natural resource that grows in many areas of Indonesia, especially in watershed ecosystems, is Suweg (the elephant foot yam) which has the scientific name Amorphophallus paeoniifolius (Dennst.) Nicolson. Local communities, such as in the Citanduy and Cimanuk watersheds of West Java, use suweg for various purposes in their lives. The study reported here aimed to document the local knowledge and development potential for suweg in the Citanduy and Cimanuk watersheds, West Java, Indonesia. The research used mixed observation methods, predominantly qualitative. The data collection technique was purposive, based on interviews (structured, semi-structured, and in-depth interviews) with several informants or community groups who were considered competent to know suweg. Data were analyzed through emic and ethical approaches. Data analysis was conducted by cross-checking, summarizing, and synthesizing. The results of the research showed that suweg grows in a range of environmental conditions on managed agroecosystem lands. The corms of suweg are peeled, cooked and eaten in a variety of side dishes. The leaves of suweg have been used as food for fish in pond-system aquaculture. The results of this study suggest that suweg has the potential for expanded development, based on sociological and ecological evidence.
Characterization of microplastic in trawl fish caught in Padang City (Indonesia) coastal area
Authors: Edwin Tivany , Primasari Budhi , Purnama R Annisa
Published: February 2023

Abstract. Edwin T, Primasari B, Purnama RA. 2023. Characterization of microplastic in trawl fish caught in Padang City (Indonesia) coastal area. Biodiversitas 24: 516-522. Marine organisms can ingest microplastics that are distributed in the oceans. It can harm marine organisms because carcinogenic materials easily attach to microplastics. Trawl fish is a commercial fish with a high demand from people in Padang City, West Sumatera, Indonesia. This study aimed to analyze the abundance of microplastics in the gastrointestinal tract of fish. Also, analyze the microplastic characteristics in trawl fish caught on Pasir Jambak Coast and Purus Coast in Padang City. The species studied were Sulphur goatfish (Upeneus sulphureus), Indian mackerel (Rastrelliger kanagurta), and White sardinella (Sardinella albella). Microplastics were identified using microscopy and FTIR spectroscopy. Microplastic abundance in Sulphur goatfish, Indian mackerel, and White sardinella was 3.89±1.36 per fish, 4.22±1.28 particles per fish, and 2.50±0.46 particles per fish, respectively. The size of the most commonly found microplastics ranged from 1-5 mm and was categorized as the Large Microplastic (LMP) type. Fourier Transform Infra-Red (FTIR) spectroscopy analysis showed that the origin of the type of microplastic polymer found was Polyethylene Terephthalate (PET). Statistically, it shows that the difference in the location and time of sampling does not provide a significant difference in the concentration of microplastics in fish and seawater. The results of this study indicated that microplastics were found in the waters and all fish samples on the coast of Padang City studied. Microplastics in the trawl fish can be used to manage plastic waste in the city to prevent a worse impact due to plastic pollution in the future.
Ecolichenology of Eastern Ghats diversity against climatic fluctuations in Kolli Hills, India
Authors: SUBBAIYAN RUBAVATHI , GANESAN AYYAPPADASAN , DHANUSKODI SARANYA
Published: February 2023

Abstract. Subbaiyan R, Ganesan A, Dhanuskodi S. 2023. Ecolichenology of Eastern Ghats diversity against climatic fluctuations in Kolli Hills, India. Biodiversitas 24: 625-635. Lichens are major components of earthbound and marine environments. A lichen is a symbiotic form of algae and fungi adapted to survive in different altitudes and environmental conditions. The lichen morphology is divided into three, based on their habitat: crustose, foliose, and fruticose lichens. Eastern Ghats (EG) contribute significantly to both the endemicity and species richness of the Indian region. However, EG forests are relatively unexplored and have received less conservation consideration than the Western Ghats. Unexplored Eastern Ghats were studied to analyze the ecolichenology against climatic fluctuations. The objective of this paper is to build a stock of epiphytic lichens within the Kolli slopes. Kolli Hills are one of the ancient richest floral and faunal biodiversity hotspots of Eastern Ghats. It is assessed from the year 2018 to that 2021 with different climatic seasonal variations. The least diversity was found with the Arthonioid > Usneoid > Scaly > Ramalinoid types. Highly denser than the Parmelioid foliose and Usneoid, the Ramlinoid species was rich in numbers with healthy thallus. The population was stopped, or the least amount of thallus growth was noticed from the high rainfall season and gradual reduction in the summer. The Ramalinoid and Parmelioid lichens were found to be easy identifiers. The richness was reduced dependently and independently with nature. The health of lichens was encountered with only morphological appurtenance. Based on the lichen group, the maximum distribution was observed in Usneoid and Ramalinoid categories. The last distribution was found with Leprose and Scaly lichens. The forest wealth was described with the denser lichen patches and the shrinkages of Parmelioid lichens, especially the Dirinaria and Parmoterma, acting as a wealth analysis tool of the forest ecosystems.
Measurement of the fractional topological charge of an optical vortex beam through interference fringe dislocation: publisher’s note
Authors: Shikder Allarakha , Nishchal Naveen K.
Published: February 2023

This publisher’s note serves to correct Appl. Opt.
62, D58 (2023).APOPAI0003-693510.1364/AO.476455
Third-Order Aberration Theory in GRIN Lenses
Authors: Minami Setsuo
Published: February 2023

In regard to the aberration theory, we have two possible approaches; Buchdahl's quasi-invariant method1), and Herzberger's point eikonal method2). Both methods utilize the derivations of the fifth order and higher order aberration theories for homogeneous optical systems.

P.J. Sands applied extensively the quasi-invariant method to inhomogeneous lenses, and established the practical third order aberration theory4).
Ray Tracing In Inhomogenous Media1
Authors: Rimmer Matthew P.
Published: February 2023

Gradient index materials, in which the index of refraction varies as a function of position, are being used commercially in high volume.2,3 Thus, the ability to easily evaluate systems using such materials is becoming more important. Since the ray paths are typically curved trajectories, ray tracing is more complicated than for homogeneous materials.
Raytracing through decentered and tilted graded-index optical systems.
Authors: Sharma Anurag , Jeyaprakash M. , Ghatak A.K.
Published: February 2023

We had earlier reported a method1 for tracing finite rays through graded index media and had shown that for a given accuracy our method is faster than existing methods. In this paper we extend this method to trace rays through decentered and tilted graded-index optical systems. In existing literature on this subject, the shift of the centre and the till of a component have generally been taken in the same plane2. Using our method, we consider general cases of tilt and decentering and discuss the effect of these defects on various total aberrations. In particular, we discuss the effect of decentering and tilts of surfaces and gradient on the imaging properties of photographic singlet designs reported by Marchand3.
Asymptotic Series Solution of the Parabolic Wave Equation in Gradient-Index Media
Authors: Taylor Leonard S.
Published: February 2023

Exact solutions of the wave equation in gradient-index media are available for only a few special mathematical models of the index of refraction variation. We note that in cases of small fractional variation of index of refraction we may reduce the wave equation to the parabolic wave equation.
2-D Branching Components Array with Distributed-Index Planar Microlens
Authors: Oikawa M. , Iga K. , Misawa S.
Published: February 2023

Optical fiber communication and electro-optic systems require wide variety of mass-producible lightwave components. However, the fact that conventional micro-optics or even guided-wave planar components need high precision optical alignment prevents us from easy production. In order to avoid this difficulty we proposed stacked planar optics1, where 2-D planar microlens array and optical components are integrated to form 2-D integrated lightwave components. In this paper we present perfomances of improved microlens array and its application to 2-D arrayed branching components.
Measurement of Numerical Aperture of Planar Microlens by Far Field Pattern Method
Authors: Misawa S. , Oikawa M. , Iga K.
Published: February 2023

The measurement of the Numerical Aperture (N.A.) of a distributed index (DI) planar microlens1) is important for its evaluation of focusing power. There have been some methods of measuring the N.A. of conventional lenses, e.g., the ratio of aperture diameter and focal length is easily determined and sometimes, the Apertmeter2) has been utilized. The planar microlens, on the other hand, has some situations different from conventional spherical lens; i.e., the size of its diameter is smaller than 1 mm and the focal length is 1.5 mm~2 mm. Moreover, the physical edge of DI microlens does not necessarily indicate the effective lens size, if the index distribution near the periphery does not suitably contribute to focusing. We must, therefore, introduce some new method for measuring N.A. of planar microlens.
An Imaging Device Using a Micro Roof Mirror Lens Array and Its Imaging Properties
Authors: Kawazu Motoaki , Inokuchi Toshiyuki
Published: February 2023

The gradient index rod lens array (1) and the strip lens (2) have been developed as unit magnification imaging devices. These devices are used widely in copiers and like systems.
Theory and Applications of the Beam Propagation Method
Authors: Thylén Lars
Published: February 2023

The beam propagation method 1,2 has been extensively employed in recent years to model various guided wave structures. This method involves an operator solution of the Hemholtz equation (or of this equation in the Fresnel approximation) which has the advantageous property that it gives a unified treatment of guided and radiation modes in complex waveguide structures, where the index is also allowed to vary in the propagation direction . Hence, an incident exciting field can be traced through the structure, and important waveguide and device properties can be calculated. These include propagation constants and modal fields3,4, loss ( e g due to bends) 5, crosstalk in switches6, switching voltage in electrooptic devices7, coupling efficiences as well as gain and attenuation in media, with gain or loss8. This makes the method ideally suited for simulation of integrated optics devices9,10. However, the method is only applicable in cases with limited transverse spatial frequency bandwidth of index profiles and field (paraxiality requirements) as well as limited index steps 11,12.
Bidirectional-BPM analysis of a 90° integrated waveguide mirror in InGaAsP/InP
Authors: Kaczmarski P. , Baets R. , Lagasse P. E.
Published: February 2023

The size of waveguide bends is one of the crucial factors influencing the overall length of integrated optical components for fibre-optic communication systems. Recently, there has been a growing interest in large-angle abrupt bends, which are realised by etching a totally reflecting mirror through a 90° waveguide corner [3] [4] [5] (Fig.1.a). This technique is promising for the realisation of single bends or large lateral waveguide off-sets (Fig.1.b). So far, 90° waveguide mirrors were implemented both on GaAs/GaAIAs [3] [4] and InGaAsP/InP [5] and the measured insertion loss of the devices reported is of the order of a few dB. Various contributions to the mirror loss are simulated in this paper by the bidirectional BPM, which is a recently developed iterative extension of the one directional BPM taking into account discrete reflections [2]. In particular, the sensitivity to mirror displacement, waveguide width and vertical inclination of the mirror facet are investigated for both TM and TE polarisation. Analytical plane-wave solutions support the reliability of the results.
Analysis of Rib Waveguides and Couplers with the Propagating Beam Method
Authors: Feit M.D. , Fleck J.A.
Published: February 2023

The growing importance of semiconductor rib waveguides and couplers has created a need for accurate numerical techniques to simulate performance. We present here results for representative rib waveguides and directional couplers that demonstrate the feasibility of accurately modeling such devices with three-dimensional PBM1 calculations.
Electrostatic Field of Electrooptic Modulators Computed with the Point Matching Method
Authors: Marcuse D.
Published: February 2023

Many integrated-optics devices are equipped with electrical contacts that serve the purpose of applying an electric field to an optical waveguide that exists at some distance beneath the surface of the dielectric material. Proper design of such structures requires that the electric field generated by the contacts be known. If the dielectric material is homogeneous, solution of the electrostatic field problem is often possible by means of a conformal mapping. However, if the dielectric structure consists of stratified layers, conformal mapping is not useful for simplifying the problem and other means must be found for computing the electrostatic potential ψ underneath the contacts.
Computer Modeling of Interferometric Microwave Traveling Wave Modulators and Switches in LiNbO3
Authors: Chung Haeyang , Chang William S. C. , Adler Eric L.
Published: February 2023

A number of single-mode electrooptical LiNbO3 channel waveguide modulators and switches are all operating on the principle of mode interference. These devices include the Mach-Zehnder, the crossing channel and the widened X (or zero gap directional coupler) devices. For operation at high microwave frequencies, they are traveling wave devices [1,2]. The electrodes of these devices are in the form of coplanar waveguide (CPW), symmetric coplanar strip (SCPS) and asymmetric coplanar strip (ACPS) microwave transmission lines. Although the basic principles of operation of these devices are well known, their design optimization is complex because many parameters are involved [3]. We shall describe here a numerical modeling procedure that could be used systematically to optimize the drive power requirement for a given bandwidth. Specifically, we shall show: (1) The bandwidth of interferometric traveling wave devices depends only on the electrode length L, the microwave velocity (represented by the microwave effective index

n

eff

m

)

and the frequency dependence of microwave attenuation. (2) Numerical calculation of the microwave attenuation and

n

eff

m

as a function of the electrode width W, gap of separation G and thickness T has been obtained. Thus the bandwidth requirement can be satisfied by appropriate choice of L, G, W and T. (3) In the first order, the optical waveguide that can be fabricated with the tightest optical mode confinement has the lowest drive power requirement. (4) The microwave drive power (not including the effect of impedance mismatch to the generator) can then be minimized by using the waveguide parameters for tight mode confinement and by varying W, T and G within the allowed range of values that satisfy the bandwidth requirement.
Ultrafast Diffraction from Rydberg Wave Packets Using High Harmonics
Authors: Schafer Kenneth J. , Krause Jeffrey L.
Published: February 2023

Rydberg wave packets have been the object of intense experimental and theoretical study over the past decade due to their many interesting semiclassical and quantum characteristics. Long-lived wave packets have been created in both hydrogen and alkali metal atoms, and localization in both the radial and angular dimension has been demonstrated [1]. It is also possible to apply the methods of quantum control to calculate optimally shaped laser pulses which create Rydberg wave packets that have a desired distribution in phase space at a specified “target” time [2]. This can take the form of, for instance, a “Schrödinger cat” state in which an electron is localized in several distinct regions of space simultaneously.
Intense Laser Interactions: Hot Electrons and High Harmonic Ionization
Authors: Van Woerkom L.D. , Evans S. , Hansch P. , Walker M.A.
Published: February 2023

We report on photoionization measurements made using intense 800 nm ultrashort pulse laser light and its high harmonics. First, we present photoelectron kinetic energy spectra showing prominent features at high kinetic energies that cannot be explained by the simpleman/rescattering theory, traditional Rydberg state resonances or other current theoretical treatments. Second, we report the first indications of multiphoton and multiple ionization using high harmonic radiation. We have measured what is believed to be two-photon ionization of both neutral and singly ionized Krypton. Ion charge state distributions for harmonic orders ranging from the 3rd to the 17th are presented for the noble gases.
Observation of nonlinear laser-electron and laser-photon scattering
Authors: Bamber C. , Boege S. , Koffas T. , Kotseroglou T. , Melissinos A.C. , Meverhofer D.D. , Reis D. , Bula C. , McDonald K.T. , Prebys E. , Burke D.L. , Field R.C. , Horton-Smith G. , Spencer J.C. , Walz D. , Berridge S. , Bugg W. , Shmakov K. , Weidemann A.
Published: February 2023

Nonlinear laser-electron and laser-photon scattering has been observed during the interaction of an intense laser with 46.6 GeV electrons in the Final Focus Test Beam at SLAC. Nonlinear laser-electron and laser-photon scattering is characterized by two dimensionless parameters.1-3
Photoelectron Spetrometry of XUV Multiphoton processes in Helium
Authors: Bouhal A. , Breger P. , Agostini P. , Constantinescu R. , Muller H. G. , DiMauro L. F. , Hamoniaux G. , Mysyrowicz A. , Antonetti A.
Published: February 2023

High-order harmonic generation by means of high-energy, femtosecond laser pulse has proved to be a convenient way to generating coherent radiation in the extreme-ultraviolet (XUV) spectral regions. Recent experiments [1,2] show that harmonic duration is much shorter than the pump one while divergence measurements show that the harmonic beam should be focussable to a fairly small spotsize and reach intensities high enough for nonlinear interactions. In this contribution we report the first electron energy spectrum(*) resulting from non-resonant multiphoton transitions induced in the XUV domain using harmonics produced in xenon by the 120 fs, 10 mJ Ti:sapphire laser at the Palaiseau facility. An annular beam geometry[3] is used to separate the fundamental from the harmonics which are focussed in a magnetic bottle electron spectrometer filled with 10-2 torr of helium by a (W-Re)-coated spherical mirror (R=70mm). The intensity of the pump laser is adjusted to .9 mJ for a cutoff at harmonics 15. Consequently, no one-photon ionization of helium is observed. Photoelectrons are detected only when the XUV radiation reflected by the mirror is focussed in the sensitivity zone of the magnetic bottle (Fig.1). This behavior is the signature of a strong intensity dependence of the ionization process and rules out one-photon processes.
Measurements of Ultrafast Dynamics in GaAs Crystals using Time-resolved X-Ray Diffraction
Authors: Rose-Petruck C. , Guo T. , Raksi F. , Squier J. , Walker B. , Weber P. M. , Wilson K. R. , Barty C. P. J.
Published: February 2023

We present initial results of picosecond time resolved diffraction from GaAs(111) crystals using plasma generated, ultrafast x-ray pulses. Laser excitation of the GaAs transfers electron population from the valence into the conduction band. Such an excitation typically produces a hot electron gas in the conduction band that thermalizes with the lattice via phonon emission with a time constant of about 2 ps.[1, 2] However, upon transfer of a few percent of all valence electrons, the cohesive energy binding the atoms in the crystal lattice changes, which can lead to a rapid modification of the crystal structure.[3-8] This process, which does not require the thermalization of electrons and phonons, can proceed on femtosecond timescales. Both effects, which substantially disturb the equilibrium crystal structure, are in principle detectable by ultrafast x-ray diffraction, as are other effects such as melting and shock wave propagation.
Wavelength Dependence of keV X-ray Generation from Xe Clusters Pumped by TW Laser Pulses
Authors: Kondo K. , Jordan C. , Borisov A. B. , Suzuki H. , McPerson A. , Boyer K. , Rhodes C. K.
Published: February 2023

A direct comparative measurement of the dependence on the wavelength of irradiation of the kilovolt x-ray yields [Xe(M) ~ 9 -15 Å and Xe(L) ~ 2.5 - 3.2 Å] multiphoton-induced from Xe clusters by excitation with intense (I > 1018 W/cm2) femtosecond pulses at 248 nm and 800 nm has been made. The spectroscopic findings demonstrate that the x-ray production is strongly reduced with excitation at the longer wavelength (800 nm). The peak strengths of the Xe(M) and Xe(L) emissions are diminished approximately by factors of 50 - 102 and ~ 3 × 103, respectively, and significant spectral modifications are also observed. This sharp reduction in the amplitude of excitation rules out a thermal model for the production of kilovolt x-rays [Xe(M) and Xe(L)] from multiphoton excited Xe clusters. These results are consistent with a dynamical mechanism of enhanced coupling which could involve ordered many-electron motions in which a dephasing of the electrons can appreciably influence both the amplitude of excitation and the threshold intensity for inner-shell vacancy production.
Scaling of Nd:Glass pumped Ti: Sapphire Chirped Pulse Amplification (CPA) systems to 100 TW and beyond
Authors: White W. E. , Price D. F. , Bonlie J. , Patterson F. G. , Stewart R. E.
Published: February 2023

We have been working on the development of high energy, ultrashort pulse laser systems based on Chirped Pulse Amplification (CPA) in Ti:Sapphire pumped by Nd:YAG and Nd:Glass. These systems begin with the now standard "front end" consisting of a mode-locked Ti:Sapphire oscillator followed by a pulse stretcher, and a regenerative amplifier pumped by a commercially available frequency doubled Nd:YAG. The resulting mJ level pulses are then amplified to several hundred mJ in Ti:Sapphire amplifiers that are also pumped by commercially available Nd:YAG lasers. At this point the pulses can be compressed to the multi-TW level. Systems of this type have become fairly common and even commercially available. However, the pump energy needed to further amplify to energies of several Joules, or even >10 J is beyond what is currently available as a standard commercial product.
Multi-pulse Interferometric Frequency Resolved Optical Gating: Real-time Phase-sensitive Imaging of Ultrafast Dynamics
Authors: Siders C. W. , Taylor A. J. , Downer M. C.
Published: February 2023

Recent advances in ultrafast laser technology and measurement techniques have pushed optical communication rates beyond a Terabit per second [1] and moved high-speed opto-electronics into the Terahertz domain [2]. Similar advances in high-field laser-matter interactions promise compact table-top sources of tunable short-pulse VUV- and X-radiation with brightness comparable to large electron storage ring facilities [3]. Also of great interest to the high energy and particle accelerator communities, large-amplitude relativistic Langmuir waves excited by super-strong ultrafast laser pulses in plasmas may lead to both “compact” (kilometer) TeV scale accelerator facilities and small laboratory/medical facility table-top electron accelerators with GeV beam energies [4]. Continued advancement in our understanding of the underlying fundamental physics in these fields depends critically on the successful development, refinement, and application of sensitive optical diagnostics with femtosecond temporal resolution. As the dominant interaction between a probe laser pulse E(t) and these materials is a shift in optical phase, E(t) → E(t)eiϕ(
t
), where ϕ(t) = (n(t)wz/c) and n(t) is the refractive index, optical diagnostics designed to directly measure the phase change ϕ(t) have shown the most promise. The inter-related techniques of spectral blueshifting [5], longitudinal (i.e. frequency domain) interferometry (LI) [6], and frequency resolved optical gating (FROG) [7] have been successfully used by many researchers to extract from spectral power density measurements sensitive details of ultrafast time-domain phase shifts. The first two of these techniques, being linear optical effects, have been shown to be powerful tools for measuring DC and slowly varying time-domain phase shifts with extremely high sensitivity (one part in 3000 of a fringe) over a temporal span of many pulse-widths about the peak of the pulse. On the other hand, the optically nonlinear FROG, which accurately recovers detailed variations in temporal phase about the intense portions of the pulse but is largely insensitive to DC and slowly varying terms, acts as a complementary diagnostic for highly structured phase shifts, such as those in ionization fronts. We have developed a new marriage of standard FROG with multi-pulse longitudinal interferometry, termed Multi-pulse Interferometric FROG, or MI-FROG, which promises to become a powerful real-time diagnostic of ultrafast dynamics: a femtosecond phase-sensitive oscilloscope if you will.
Radiological applications of hard X-ray emission from a laser-produced plasma
Authors: Grätz M. , Tillman C. , Nykänen A. , Kiernan L. , Wahlström C.-G. , Svanberg S. , Herrlin K.
Published: February 2023

The use of laser-produced plasmas as soft x-ray sources has been investigated for a long time. Laser pulse durations were normally of the order of nanoseconds, and high peak powers were consequently only available at very large laser facilities. This situation changed with the development of terawatt laser systems based on the chirped-pulse amplification technique. With these laser systems, peak powers in the terawatt range became available in ultra-short pulses, leading to focused intensities well above 1017 W·cm−2.
Hard X-ray Emission from Femtosecond Laser Interaction in Overdense Plasmas
Authors: Andreev A.A. , Novikov V.N. , Platonov K. Yu. , Gauthier J.-C.
Published: February 2023

The recent development of ultra-short pulse lasers has made possible the investigation of laser matter interaction at ultra-high intensities. For sub-picosecond pulses, a hot and overdense plasma is produced very rapidly during the rise of the pulse and further laser interaction occurs with this plasma. One of the results of the interaction is the generation of fast electrons and of intense hard x-ray emission. The x-ray pulse duration is determined by the mean free path of the fast electrons in the target material. It can be very short (< 1 ps) and its intensity sufficient to be registered by the usual methods. With high laser pulse repetition rates, it has been demonstrated [1] that one can obtain an instantaneous signature of fast-x-ray dense-matter interaction processes. The high energy of the x-ray photons (up to ≈ 1MeV) makes it possible to study small size objects and even to excite nuclear levels. Numerous papers [2-7] have been devoted to the study of femtosecond laser pulse interaction with plasmas. In this paper, we calculate the electron energy distribution function in the presence of the laser field, the absorption coefficient, and the parameters of the fast electron flux in the plasma. Our absorption results are in agreement with previously published [3-5] papers. A new feature of our calculations is the determination of the energy and spectrum characteristics of the hard x-ray pulse produced by the interaction of an intense laser with a solid-state target.
Continuum lowering in 100-fs laser produced plasmas
Authors: Nantel M. , Buma T. , Workman J. , Maksimchuk A. , Umstadter D.
Published: February 2023

We present what we believe to be the first measurements of continuum lowering in high-density plasmas produced by 100-fs laser pulses. Continuum lowering arises in dense plasmas when the excited states of an ion are perturbed by the close proximity of the neighboring ions, and can be a useful density diagnostic. It is a fundamental atomic physics concept in high-density plasmas important to work in X-ray lasers, ICF plasma diagnostics, astrophysics and plasma simulations. In our experiments, a 10-Hz, 100 mJ 100-fs laser system is used to create the plasmas studied, essentially providing a delta-function heat pump which terminates before significant hydrodynamic motion occurs. Continuum lowering was observed both in the high-density, high-temperature expanding plasma plume and in the solid, low-temperature shocked material of the target. In the expanding plasma, we used XUV emission spectroscopy to observe the suppression of high-lying excited levels of He-like and H-like boron. In the compressed plasma behind the shock wave, we used XUV absorption spectroscopy to measure the shifts in inner-shell absorption edges in boron (K-edge) and in aluminium (L-edge).
Low energy pumped X-ray lasers with saturated transient gain
Authors: Nickles P.V. , Kalachnikov M.P. , Schnürer M. , Sandner W. , Shlyaptsev V.N. , Danson C. , Neely D. , Wolfrum E. , Key M. , Behjat A. , Demir A. , Tallents G. , Pert G.J. , Warwick J. , Lewis C.
Published: February 2023

Collisionally excited X-ray lasing in [Ne]-like Ti with a gain value of 19 cm-1 at a drastic reduced pump level of only a few Joules was demonstrated recently [1]. This achievement is based on a novel two step excitation scheme, which was proposed some years ago [2]. The scheme comprises at first a long (ns) heating pulse to establish a [Ne]-like ionic stage of desired target atoms in a plasma and second a short (ps) excitation pulse to produce efficiently a transient population inversion in the [Ne]-like ions. Due to the short pulse produced fast heating of the preformed plasma, a transient inversion [2] occurs, which is related to the different population rates of the levels via collision and not determined by the slower relaxation rates of the excited levels relevant in the quasi-steady state (QSS) regime. The transient inversion yields favourably much higher gain values (several tens of cm-1) as well shorter X-pulse output as obtained in the QSS regime (several cm-1) with long pulse pumping.
Enhanced harmonic generation using pulse shaping
Authors: Rundquist Andy , Zeek Erik , Wang Haiwen , Chang Zenghu , Murnane Margaret , Kapteyn Henry , Christov Ivan
Published: February 2023

Harmonic generation from ultrafast, ultra-intense lasers has proven to be an excellent source of coherent radiation in the soft x-ray regime.[1,2] Our recent work[3,4] has shown that very short driving pulses can generate broad bandwidth harmonic peaks, which are tunable, and with a cut-off at wavelengths substantially shorter than harmonics produced with longer duration pulses. In this work, we show how shaping the amplitude and phase of our laser pulses, to ensure faster risetimes and and optimal shapes, can enhance the efficiency of harmonic generation, as well as extend the plateau to even shorter wavelengths. We employ novel shaping techniques, using birefringent filters, and spectral shaping elements, to produce these effects.
Spectral-Spatial Measurements of Fundamental and Third Harmonic Light Scattered from Ionizing Gas in the Focus of a 25fs Laser Pulse
Authors: Peatross J. , Backus S. , Zhou J. , Murnane M. M. , Kapteyn H. C.
Published: February 2023

We recently reported1 a ~0.1% efficiency for converting 800nm, 25fs laser pulses into the third harmonic at 267nm by simply focusing 1mJ pulses in air or in other gases such as argon. Most importantly, the UV pulses were measured to be very short in duration (~16fs). For our laser conditions, we found third harmonic conversion to be most efficient when focusing with a relatively loose geometry (f/30-f/40). During the interaction, a plasma is produced in the focus, and the laser beam undergoes blueshifting and spatial distortions as ionization of the gas takes place.2-4 The goal of the present work is to gain insight into this complex interaction (i.e. propagation and distortion of the fundamental as well as the generation and propagation of third harmonic light) via a study of the spectral and spatial properties of the emerging light.
Ultra-Intense Lasers for Fast Ignition in Inertial Confinement Fusion at ILE, Osaka
Authors: Yamanaka T. , Kato Y. , Kitagawa Y. , Kodama R. , Takabe H. , Fujita H. , Kanabe T. , Nakatsuka M. , Mima K.
Published: February 2023

Progress in high power short pulse laser using a chirped-pulse amplification technique[1] is opening the possibility of an additional heating concept "fast ignition" [2] in Inertial Confinement Fusion (ICF). In the concept, the compressed fuel with a high fuel density created by a conventional laser implosion is heated by an ultra-intense short pulse laser (a few ps) before a core is disassembled (< a few ten ps). The concept will give us reduction of the required laser energy and the implosion uniformity for ignition in ICF.
X-laser induced nuclear decay: Resonance internal conversion
Authors: Zon B.A. , Chernov V.E.
Published: February 2023

The behaviour of nuclei in intense electromagnetic field is a subject of great theoretical interest. Considerable changes in these processes (e. g. in internal conversion, IC) could be achieved by resonanse interaction between nuclei and their electronic shells, when the correspondent nuclear and electronic levels are sufficiently close and the defect of resonance is compensated by laser radiation. As an example of such processes, the resonance internal conversion (LIDIC) in metastable nuclei [1, 2, 3] can be considered. Experimental study of the laser field interaction with metastable nuclei can provide an information about important nuclear characteristics, such as energies and multipolarities of nuclear transitions, anomalous internal conversion coefficients etc., which are not well identified for some nuclei. Moreover, of certain interest can be an acceleration of nuclear decay due to the LIDIC-process, and even (at sufficiently high intensities of the laser field) a coherent X-ray radiation due to electron transition into the deep vacancy created by LIDIC-process or (at still higher intensities) a coherent 7-radiation due to the nuclear transitions.