In-band Emission Research Articles

Modeling the hundreds-of-nanoseconds-long irradiation of tin droplets with a 2 µm-wavelength laser for future EUV lithography

Abstract The properties of an extreme ultraviolet (EUV) source driven by hundreds-of-nanoseconds-long laser pulses of λ laser = 2 µm wavelength are investigated through radiation-hydrodynamic simulations. We show that single-pulse irradiation of 30 µm-diameter tin droplets can generate in-band energies ∼ 30 mJ directed in the 2π sr solid angle subtended by the collector mirror, yielding energies ∼100 mJ produced from 45 µm-diameter droplets. Time-integrated in-band EUV emission profiles, generated by taking Abel transforms of the local net in-band emissivity, reveal EUV source sizes in the axial (laser) direction × radial direction of ∼600 (1000) × 100 (150) µm2 for 30 (45) µm-diameter droplets. We find that approximately 74% of the total in-band emission is produced during the first half of the total propulsion distance irrespective of droplet size or laser intensity. Furthermore, we propose a one-dimensional analytical propulsion model to qualitatively explain the simulated droplet trajectory and to predict the time taken for the droplet to vaporize. These findings offer motivation for the development of high-power EUV sources based on single-pulse, hundreds-of-nanoseconds-long irradiation of tin droplets.

A Review of the 3GPP-Compatible Model of 5G in-Band Emissions in Uplink Resource Allocation in Hybrid Network

In-band emission represents a critical metric for assessing the reliability of a mobile communication network and ensuring quality of service (QoS) for end users. In the 5G network deployment, due to the limited availability of frequency spectrum, mobile users and internet-of-things (IoT) devices will transmit on the same frequency bands, necessitating more stringent in-band interference management to facilitate interference-free communication. In order to ensure that high-power user equipment (UEs) accessing the shared 5G uplink channel are able to communicate without disruption and without interfering with low-power devices, it is imperative to undertake in-band emissions analysis and control. This paper explores the issue of in-band emission interference, which pertains to the interference that arises in unallocated sub-bands within a specific bandwidth. Specifically, this investigation delves into the modeling approach and regulated in-band emissions within a non-standalone (NSA) 5G network. To verify compliance with 3GPP requirements for in-band emissions regulations, an over-the-air (OTA) testing system is employed to examine in-band emissions in the physical uplink shared channel (PUSCH). The study employs various resource block distributions, offsets, and modulation techniques within the specified NR channel bandwidth. All simulations are based on 3GPP specifications.

Influence of CO2-laser pulse parameters on 13.5 nm extreme ultraviolet emission features from irradiated liquid tin target

A laser-produced plasma excited by CO2 laser pulses with various durations and energies on liquid tin droplets with diameters of 150 μm and 180 μm is considered. A two-dimensional radiative-magnetohydrodynamic code is used for numerical simulations of multicharged ion plasma radiation and dynamics. The code permits to understand the plasma dynamics self-consistent with radiation transport in non-local equilibrium multicharged ion plasma. Results of simulations for various laser pulse durations and 75 ÷ 600 mJ pulse energies with both Gaussian and experimentally taken temporal profiles are discussed. It is found that if the mass of the target is big enough to provide the plasma flux required (the considered case) a kind of dynamic quasi-stationary plasma flux is formed. In this dynamic quasi-stationary plasma flux, an interlayer of relatively cold tin vapor with mass density of 1 ÷ 2 g cm−3 is formed between the liquid tin droplet and low density plasma of the critical layer. Expanding of the tin vapor from the droplet provides the plasma flux to the critical layer. In critical layer the plasma is heated up and expands faster. In the simulation results with spherical liquid tin target, the conversion efficiency into 2π is of 4% for 30 ns full width half maximum (FWHM) and just slightly lower—of 3.67% for 240 ns FWHM for equal laser intensities of 14 GW cm−2. This slight decay of the in-band extreme ultraviolet (EUV) yield with laser pulse duration is conditioned by an increasing of radiation re-absorption by expanding plasma from the target, as more cold plasma is produced with longer pulse. The calculated angular distributions of in-band EUV emission permit to optimize a collector configuration.

Distance Based Power Control for D2D Communication in LTE-Advanced Networks

Device to device communication systems places a very important role in handling both voice and data services efficiently in LTE-A networks. Power control techniques that we adopt for efficient D2D communication becomes a challenging issue. D2D and cellular signals under the same network may result in In-band Emission Interference (IEI). This degrades discovery range which result in loss of energy efficiency, throughput and hence increases the power requirement in both uplink and downlink transmissions. In this paper, a power control algorithm is introduced which greatly helps in saving power in LTE-Advanced networks for D2D communication. Power calculation mechanisms for D2D users and cellular users are shown separately. Based on mode selection, transmit and receive power requirements are evaluated to obtain the preset Quality of Service (QoS) parameters. The simulation results presented in the proposed method demonstrates the effectiveness of power consumption in LTE-Advanced networks for device to device communication.

Navigator Notes

Navigator Notes

An overview of the effects of out‐of‐band interference on GNSS receivers

<h3>Abstract</h3> This paper addresses the wide range of mechanisms through which out-of-band interference can disrupt the functioning of GNSS receivers. These mechanisms include saturation and desensitization of front-end low noise amplifiers, mixers and other circuitry; reciprocal mixing effects that arise from the fact that receivers cannot generate a perfect tone to down-convert the desired signals; intermodulation products; aliasing of out-of-band emissions that remain after filtering into the receiver’s passband; and the reception of in-band (to GNSS) emissions that are always present due to imperfections in the signal generation and filtering of the interfering system. These mechanisms are described in detail and mitigation approaches for each are discussed.

Calculation of the extreme-ultraviolet radiation conversion efficiency for a laser-produced tin plasma source

This article presents the calculation results on the conversion efficiency (CE) of 1.064 μm laser-produced plasmas (LPPs) extreme-ultraviolet (EUV) tin (Sn) light sources with the Gaussian and a triangular-flat-topped like laser pulse temporal shapes. The computational model includes a collisional-radiative model and 1D hydrodynamics code that predicts reported experimental and theoretical results on the CE of 1.064 μm and 10.6 μm LPP EUV sources with the planar and mass-limited spherical Sn targets. The calculations for the case of a spherical target reveal that an optimum triangular-flat-topped like laser pulse generates a higher CE compared to the Gaussian pulse, especially, for the longer laser pulse duration than ≈ 30 ns. The study demonstrated that a rising intensity rate of the laser pulse has a vital role to optimize the CE as well as to prolong the in-band (13.5 ± 0.135 nm) spectral emission of a small Sn spherical target. The model predicts a ≈ 30 ns rising time duration for a linearly increasing intensity of triangular-flat-topped 1.064 μm laser pulse is necessary to obtain a maximum CE with a typical ≈ 40 μm diameter liquid Sn droplet.

A comprehensive experimental characterisation of a novel porous media combustion-based thermophotovoltaic system with controlled emission

The high temperatures of combustion systems make them suitable for coupling with thermophotovoltaic systems. In practice, it is quite challenging to reduce heat losses and the spectral mismatch between the emission of the combustion source and the spectral response of photovoltaic (PV) cells. In an effort to pull these disparate energy-focussed research fields together, this paper explores the use of a low-cost erbia (Er2O3) coating on a novel porous media combustion-based thermophotovoltaic (PMC-TPV) reactor for continuous combined heat and power generation. In this work, three different configurations were analysed, including a non-coated porous foam, a coated porous foam, and a coated quartz container. As such, this study provides the first in-depth analysis and characterisation of all salient components of a PMC-TPV system. It includes a detailed characterisation of a 24-cell gallium antimonide (GaSb) array, which was attached to a heat sink and used to harvest the radiant emission from a hot (>1200 °C), yttria-stabilised zirconia/alumina composite (YZA) ceramic foam. Since the ceramic foam does not have an ideal emissivity curve for these cells, the ability of the erbia coating to control the spectral emission was measured. The results show that by applying the erbia coating to the outer surface of the YZA foam (e.g. using a simple 2-step process of dip coating followed by curing/calcination), it is possible to increase performance, achieving a maximum in-band emission fraction of 25.4% at a firing rate of 1300 kW/m2 (i.e. around 10% of increase than that for non-coated configuration), which provides a temperature of 1285 °C. Additionally, a maximum power output of 1 W was achieved by using erbia coating on YZA foam. For the third configuration, the use of the erbia coating on the quartz tube (instead of the YZA foam) leads to an increase in the maximum core temperature of the reactor up to 1443 °C; however, this also leads to a decrease in electrical performance due to a lower in-band fraction. These findings show that applying an erbia coating on an industrial radiant emitter could enable a combined heat and power processes to gain around 30% increase of electrical output. Finally, since the PV fill factor was lower than expected, and electroluminescence measurements indicated cell damage, these findings also reveal the importance of continuously monitoring PV parameters in PMC-TPV systems.

Relay Positions Considering Interference from Other Sub-Channels in OFDMA-Based D2D Group-Casting Systems.

Device-to-device (D2D) communication is a technique for direct communication between devices without going through a base station or other infrastructure. D2D communication technology has the advantages of improving spectrum efficiency and reducing transmission delay and transmission power. In D2D communication systems, orthogonal frequency-division multiple access (OFDMA) is widely used to maintain similarities with cellular communication systems and to secure transmission distance. OFDMA allows flexible and efficient use of frequency resources by allocating sub-channels independent to each user. In this paper, we consider a D2D overlay system that uses different sub-channels for cellular and D2D communications. In theory, the signals on different sub-channels of an OFDMA system are orthogonal and not interfered with each other. However, in a D2D communication system, which operates in a distributed manner, there is non-negligible interference from other sub-channels because of in-band emissions. In this paper, we address the performance degradation resulting from the interference from other sub-channels for OFDMA-based D2D group-casting systems. We consider three different scenarios of D2D relay, and we find the relay position that minimizes the outage probability. The simulation and analytical results show that the optimal location of a relay can be considerably different according to the source location and the target scenario.

In-Band Emission Interference in D2D-Enabled Cellular Networks: Modeling, Analysis, and Mitigation

Next-generation network is considered as a device-to-device (D2D)-enabled system. The overlay in-band scheme can be used by the cellular user equipments and D2D user equipments (DUEs) to send data. The cellular and D2D links experience the in-band emission interference (IEI) from the DUEs that use the adjacent frequencies. This paper models the IEI impact by using stochastic geometry and analytically investigates this impact on cellular and D2D links. The IEI inter-cell and IEI intra-cell are separately assessed, and the expected D2D resource block (DRB) reuse factor is evaluated. Furthermore, the distance-density-based strategy is proposed to mitigate the IEI by controlling the number and location of served DUEs for each DRB. Also, the optimal power allocation algorithm is proposed by calculating the optimal DUEs transmission power profile that mitigates IEI and maximizes DUEs sum rate. The performance is improved significantly for the proposed methods. The application scenario is identified for each mitigation method.

Resource Selection Scheme for the Transmission of Scheduling Assignment in Device-to-Device Communications

Device-to-device (D2D) communications facilitate a number of services that are based on the exchanged information and data that are within the proximity of mobile devices. To enable robust and effective D2D communications, the D2D control signal should primarily be successfully received, even when it has been subject to collision and interference that are caused by a large number of neighboring devices. Since the broadcast type of communication is generally considered for D2D services, the Tx-side operation should be designed for higher reception performances. By using channel-quality metrics such as the signal-to-interference-plus-noise ratio as the basis for revealing the relationship between the resource selection and the decoding probability, a novel resource-selection scheme to manage the interference and the in-band emission in terms of the transmission of scheduling assignment (SA) messages was developed in this paper. Through system-level simulations, and in contrast with the conventional SA-selection method, the proposed scheme increases the decoding performance.

LTE D2D 디스커버리에서 무작위 자원 선택 방법에 대한 성능 분석

LTE D2D는 근접한 단말끼리의 직접적인 정보 교환을 통해 셀룰러 시스템의 데이터 트래픽 부하를 해결하는 핵심 기술이다. 특히 D2D 디스커버리는 LTE D2D를 위한 첫 단계로서 단말이 각자의 상태 정보를 주변 단말에게 브로드캐스트 하여 자신을 알리는 과정이다. 디스커버리 메시지 전송의 안정성을 평가하기 위해 시뮬레이션 기반의 성능 평가가 수행되었지만, 한정적인 상황에서 이루어진 경우가 많아 본 논문에서는 일반적인 환경에서 이를 평가할 수 있는 수학적 분석을 제안한다. 제안하는 분석은 확률 기하 이론을 바탕으로 수행되며, 자원 충돌과 인밴드 방사에 의한 간섭의 효과를 모두 고려한다. 우리는 디스커버리 메시지의 수신 성공 확률을 송수신 단말 간의 거리의 함수로 유도하고, 시뮬레이션 결과를 통해 제안하는 분석의 정확도를 확인한다. Long Term Evolution device-to-device (LTE D2D) is a key technology to mitigate data traffic load in a cellular system. It facilitates direct data exchange between neighboring users, which is preceded by D2D discovery. Each device advertises its presence to neighboring devices by broadcasting its discovery message. In this paper, we develop a mathematical analysis to assess the probability that discovery messages are successfully transmitted at the D2D discovery stage. We make use of stochastic geometry for modeling spatial statistics of nodes in a two dimensional space. It reflects signal to noise plus interference ratio (SINR) degradation due to resource collision and in-band emission, which leads to the discovery message reception probability being modeled as a function of the distance between the transmitter and the receiver. Numerical results verify that the newly developed analysis accurately estimates discovery message reception probabilities of nodes at the D2D discovery stage.

Carrier Sensing for OFDMA-Based D2D Group-Casting Systems

Device-to-device (D2D) communications refer to direct communications between two or more devices without transferring data through the base station or other infrastructure. For synchronous D2D communication systems in most recent researches and development, orthogonal frequency-division multiple access (OFDMA) or single-carrier frequency-division multiple access (SC-FDMA) is considered to increase the communication coverage and to maintain the similarity with the cellular communication systems. One important design consideration for OFDMA-based (or SC-FDMA-based) D2D communication systems, particularly in an ad-hoc network mode, is the in-band emission effect, which corresponds to the mutual interference between different signals over other subchannels in the same time slot. To avoid interference from other transmitters or to other receivers, a transmitter may perform carrier sensing, which allows for transmission only when the measured interference is below the given threshold. Since the characteristics of the performance degradation due to other-channel interference (OCI) can be quite different from those by cochannel interference (CCI), the interference measurement must be carefully considered for carrier sensing in OFDMA-based D2D communication systems. This paper discusses physical carrier sensing for interference management in D2D group-casting or broadcasting systems and proposes a mechanism that efficiently avoids the interference from other subchannels. More specifically, outage probability is derived by taking both OCI and CCI into account and is then employed as a reference for the carrier sensing level in the course of selecting the resource blocks (RBs) for D2D communication. We demonstrate that our proposed carrier sensing scheme can significantly increase the areal capacity subject to the given target outage performance.

Characterization of a hybrid target multi-keV x-ray source by a multi-parameter statistical analysis of titanium K-shell emission

We have studied the titanium K-shell emission spectra from multi-keV x-ray source experiments with hybrid targets on the OMEGA laser facility. Using the collisional-radiative TRANSPEC code, dedicated to K-shell spectroscopy, we reproduced the main features of the detailed spectra measured with the time-resolved MSPEC spectrometer. We have developed a general method to infer the Ne, Te and Ti characteristics of the target plasma from the spectral analysis (ratio of integrated Lyman-α to Helium-α in-band emission and the peak amplitude of individual line ratios) of the multi-keV x-ray emission. These thermodynamic conditions are compared to those calculated independently by the radiation-hydrodynamics transport code FCI2.

Effects of the dynamics of droplet-based laser-produced plasma on angular extreme ultraviolet emission profile

The emission distribution of extreme ultraviolet (EUV) radiation from droplet targets is dependent on the dynamics of the laser-produced plasma. The EUV emission is measured on a 2% bandwidth centered at 13.5 nm (in-band). The targets of the laser are small (sub-50 μm) tin droplets, and the in-band emission distribution is measured for different laser irradiances and droplet sizes at various angular positions. Larger droplets lead to a faster decay of EUV emission at larger angles with respect to the laser axis. A decrease in laser irradiance has the opposite effect. The measurements are used together with an analytical model to estimate plume dynamics. Additionally, the model is used to estimate EUV emission distribution for a desired droplet diameter and laser irradiance.

Three-dimensional extreme ultraviolet emission from a droplet-based laser-produced plasma

The emission of extreme ultraviolet radiation in a 2% bandwidth centered at 13.5 nm (in-band) is measured in one hemisphere. The targets of the laser are tin droplets. In-band emission is measured at angles from the laser axis larger than 120°. Analytical models representing the physical processes are developed and calibrated with the experimental data. In the models two assumptions are investigated, isentropic and isothermal 2D-axisymmetric expansion. The parameters of the models are the density distribution of the plasma and the location where the EUV emission is centered. The parameters are inferred by the calibration of the models with the experimental data. The predictions of the models are validated with experiments where slab targets were used.

Modular EUV Source for the Next Generation Lithography

The present work, performed in the frame of the EXULITE project, was dedicated to the design and characterization of a laser-plasma-produced extreme ultraviolet (EUV) source prototype at 13.5 nm for the next generation lithography. It was conducted in cooperation with two laboratories from CEA, ALCATEL and THALES. One of our approach originalities was the laser scheme modularity. Six Nd:YAG laser beams were focused at the same time on a xenon filament jet to generate the EUV emitting plasma. Multiplexing has important industrial advantages and led to interesting source performances in terms of in-band power, stability and angular emission properties with the filament jet target. A maximum conversion efficiency (CE) value of 0.44% in 2π sr and 2% band-width was measured, which corresponds to a maximum in band EUV mean power of 7.7 W at a repetition rate of 6 kHz. The EUV emission was found to be stable and isotropic in these conditions.

A 54–862-MHz CMOS Transceiver for TV-Band White-Space Device Applications

A 54-862-MHz single-chip CMOS transceiver with a single LC voltage-controlled oscillator (VCO) fractional- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> synthesizer is developed for TV-band white-space communications and cognitive radio applications. The transceiver is based on a single-conversion zero-IF architecture with integrated harmonic filtering capability. A combined harmonic rejection mixer and coarse RF tracking filter significantly lessens the in-band harmonic emission problem in the transmitter, as well as the harmonic mixing problem in the receiver. A fractional- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> phase-locked loop (PLL) with only a single LC VCO and a wideband multimodulus local oscillator (LO) generator seamlessly covers the entire band. A wideband semi-dynamic divide-by-1.5 circuit is adopted in the LO generator to reduce the VCO tuning range requirement by 25 %. A pseudoexponential capacitor bank structure in the LC VCO substantially reduces the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VCO</sub> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">step</sub> variations across the total band, which is beneficial for maintaining the PLL loop stability and dynamics over the wide band. The transceiver is implemented in 0.18-μ m CMOS, and operates with a single 1.8-V supply. The transmitter delivers a nominal output power of -3 dBm, and exhibits OP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1 dB</sub> of >; +6.4 dBm, OIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> of >; +15.9 dBm, and error vector magnitude (EVM) of <; -34.7 dB for 64-QAM signal. The image and carrier leakage calibration circuits suppress the leakage components below -41 dBc across the entire band. The receiver achieves about 100-dB gain dynamic range, 3.5-6.9-dB noise figure, <; -29-dB EVM, and -43.4/-59.7-dBc third/fifth harmonic mixing suppression. The synthesizer and LO generator achieves the integrated phase noise <; 0.8 rms degree over the entire band.

Investigation of the dynamics of the Z-pinch imploding plasma for a laser-assisted discharge-produced Sn plasma EUV source

Dynamics of the imploding plasma and its relations to the 13.5 nm EUV emissions have been experimentally investigated for a laser-assisted Sn based discharge-produced plasma EUV source. The behaviours and two-dimensional electron density distributions of the EUV-emitting plasma were obtained using the time-resolved shadowgraph and Nomarski interferometric techniques. Observation of the plasma piston in the prepinch phase justified the validity of the zero-dimensional thin-shell model, from which the ion charge state of the prepinch plasma in the cathode region was estimated. The sausage (m = 0) instability that usually enhances the EUV emission was observed, with the radial electron density distribution that displays a concave shape at the crest of the plasma and a bell shape at the neck; the maximum of the electron density is located at one peak of the concave distribution at the crest instead of the neck. Intense EUV emission was produced by the Z-pinch plasma with the electron density (2.0–3.0) × 1018 cm−3. Moreover, the shock waves generated in the anode region can also produce in-band EUV emission with the intensity of 30% of that from the Z-pinch plasma.

Rare-earth plasma extreme ultraviolet sources at 6.5–6.7 nm

We have demonstrated a laser-produced plasma extreme ultraviolet source operating in the 6.5–6.7 nm region based on rare-earth targets of Gd and Tb coupled with a Mo/B4C multilayer mirror. Multiply charged ions produce strong resonance emission lines, which combine to yield an intense unresolved transition array. The spectra of these resonant lines around 6.7 nm (in-band: 6.7 nm ±1%) suggest that the in-band emission increases with increased plasma volume by suppressing the plasma hydrodynamic expansion loss at an electron temperature of about 50 eV, resulting in maximized emission.