Laser Power Consumption Research Articles

Influence of process parameters on the power consumption of high-speed laser directed energy deposition

Additive manufacturing offers many technological advantages, especially for individual parts and lightweight design. The novel process of HighSpeed Laser Directed Energy Deposition (HS DED-LB) has much faster feed rates and hence higher deposition rates than other metal-based processes including conventional Directed Energy Deposition, and thus offers great potential for the industry due to the resulting short process times. Contrary to the operational characteristics, the ecological performance of HS DED-LB regarding the selected process parameters is sparsely investigated. Within this scope of sustainability, especially approaches to model and reduce the energy demand are required. Within an HSL DED-LB machine, the laser, the powder feeder, the extractor, the trajectory system, and the subsystem with the cooling unit require energy depending on their respective selected process parameters. To investigate which process parameter influences the energy demand of the respective unit and to what extent, full factorial experiments were conducted for each unit of a HS DED-LB machine. Additionally, it was investigated how the energy demand depends on the set process parameters. The results indicate that, except for the laser spot diameter, all process parameters (laser power, trajectory speed, scan path, stirrer speed, conveyor disc speed, extraction volume per hour) have a significant influence on the energy demand.

Influence of preheating temperature and printing speed on interlaminar shear performance of laser‐assisted additive manufacturing for CCF/PEEK composites

AbstractContinuous carbon fiber reinforced poly‐ether–ether–ketone (CCF/PEEK) shows great potential in engineering applications attributed to superior mechanical properties together with excellent thermal and chemical resistance. In this study, a laser‐assisted additive manufacturing device was established to accurately collect and control the preheating temperature based on a coaxial infrared temperature measurement system. The influence on laser power consumption, interlaminar shear performance, and failure mechanism was investigated in condition of different preheating temperatures and printing speeds. Results indicated that the laser‐preheated specimens showed much higher ILSS with maximum values and increasing percentage reached 33.48 MPa and 157.0% compared to unpretreated specimens. With the increase of preheating temperature and printing speed, more laser power was consumed, while the ILSS and increasing percentage increased firstly and then decreased. The strengthening effect on the interlayer bonding was ascribed to promoting the penetration of PEEK molecular chain ends between adjacent layers, increasing the fluidity and enhancing the bonding effect between adjacent filament together with improving the impregnation behavior of the inner fibers. The proposed interlaminar strengthening method based on laser‐assisted preheating provides potential application prospects in aerospace and automotive industries.

Characteristics and experimental analysis on force and heat transfer in laser pulse-assisted metal transfer process

In the laser pulse-assisted metal transfer process, the recoil force generated at the laser incident point replaced the electromagnetic force. A stable one droplet per pulse (ODPP) short-circuiting or spray transfer process obtained at a relatively low current. The morphology of the solid-liquid interface changes after the laser incident, and there is a relatively complicated force-heat interaction phenomenon/process. Firstly, the evaporation mass of the droplet surface after laser irradiation was measured, and the evaporation power consumption of the laser to the droplet was calculated. According to the melting increment of the welding wire, the melting power consumption of the pulse laser on the welding wire was calculated. The dynamic change process of metal plume was observed by a high-speed camera. According to the experimental calculation, the initial velocity of droplet falling off the welding wire was measured, and the horizontal and vertical impact force of the pulsed laser on the droplet was obtained. The total evaporation recoil force was 7.81 × 10−2 N. Secondly, the temperature changes of characteristic points around the molten pool under different laser process parameters were measured. With the increase of laser pulse frequency/laser power, although the heat input of the base metal gradually increased, the measured temperature rise of the characteristic points was less than the temperature of the laser-arc hybrid process. The deposition rate of dual-pulse laser-assisted GMA welding at 75 Hz is about 1.4 times that of traditional MIG welding.

ARXON: A Framework for Approximate Communication Over Photonic Networks-on-Chip

The approximate computing paradigm advocates for relaxing accuracy goals in applications to improve energy-efficiency and performance. Recently, this paradigm has been explored to improve the energy-efficiency of silicon photonic networks-on-chip (PNoCs). Silicon photonic interconnects suffer from high power dissipation because of laser sources, which generate carrier wavelengths, and tuning power required for regulating photonic devices under different uncertainties. In this article, we propose a framework called AppRoXimation framework for On-chip photonic Networks (ARXON) to reduce such power dissipation overhead by enabling intelligent and aggressive approximation during communication over silicon photonic links in PNoCs. Our framework reduces laser and tuning-power overhead while intelligently approximating communication, such that application output quality is not distorted beyond an acceptable limit. Simulation results show that our framework can achieve up to 56.4% lower laser power consumption and up to 23.8% better energy-efficiency than the best-known prior work on approximate communication with silicon photonic interconnects and for the same application output quality.

On the routing and scalability of MZI-based optical Beneš interconnects

Silicon Photonic interconnects are a promising technology for scaling computing systems into the exa-scale domain. However, there exist significant challenges in terms of optical losses and complexity. In this work, we evaluate the applicability of a thermally/electrically tuned Beneš network based on Mach–Zehnder Interferometers for on-chip and inter-chip interconnects as regards its scalability. We examine how insertion loss, laser power and switching energy consumption scale with the number of endpoints. In addition, we propose a set of hardware-inspired routing strategies that leverage the inherent asymmetry present in the switching components. We evaluate a range of network sizes, from 16 up to 256 endpoints, using 8 realistic and synthetic workloads and found very promising results. Our routing strategies offer a reduction in path-dependent insertion loss of up to 35% in the best case, as well as a laser power reduction of 31% for 32 endpoints. In addition, bit-switching energy is reduced by between 8% and 15% using the most efficient routing strategy, depending on the communication workload. We also show that workload execution time can be reduced with the best strategies by 5%–25% in some workloads, while the worst-case increases are at most 3%. Using our routing strategies, we show that under the examined technology parameters, a 32-endpoint interconnect can be considered for the NoC domain in terms of insertion loss and laser power, even when using conservative parameters for the modulator.

Ultralow power consumption of a quantum cascade laser operating in continuous-wave mode at room temperature.

We report an ultralow power consumption of a quantum cascade laser (QCL) emitting at λ ∼ 4.6 µm operating in continuous-wave mode at room temperature. The ultralow power consumption is achieved by using a high gain active region and shortening the device size. For the device with a 0.5-mm-long cavity and 3.2-µm-wide ridge, the threshold power consumption is as low as 0.26 W with an optical output power of 12.6 mW at 10 °C in continuous-wave mode, which represents the world's most advanced level. Furthermore, the threshold power consumption varies linearly with the operating temperature, where the linear change rate of 2.3 mW/K from 10 to 40 °C is low. As a result, the devices also show low threshold power consumption values of 0.33 W even at 40 °C in continuous-wave mode with an optical output power of 6.1 mW. In addition, the lasers can maintain a single-mode operation due to the short cavity length even if no distributed feedback grating is applied.

Experimental study on power consumption of laser and induction assisted machining with inconel 718

Abstract Thermally-assisted machining (TAM) is a developed machining method to improve the machinability of difficult-to-cut materials. TAM is preheating the material in front of the cutting tool and machining the preheating area. However, this machining method is carried out by adding a preheating device to a general machine tool. Therefore, this has the effect of increasing total power consumption compared with conventional machining (CM) methods. Power consumption analysis is vital in view of the efficiency of the machining methods and conditions. However, research on the power consumption of thermally-assisted machining is still lacking. This paper focuses on the machining efficiency according to power consumption in difficult-to-cut material machining of conventional machining, laser-assisted machining (LAM), and induction-assisted machining (IAM) with Inconel 718. Thermal analysis was performed to determine the effective depth of cut. In the case of IAM, a thermal-electromagnetic coupled analysis was performed to determine the dwell time for preheating and effective depth of cut. The power consumption, cutting force, and surface roughness was analyzed according to various machining conditions. Experimental results verified the efficiency of LAM and IAM in comparison with CM.

GPUOPT

On-chip photonics is a disruptive technology, and such NoCs are superior to traditional electrical NoCs in terms of latency, power, and bandwidth. Hence, researchers have proposed a wide variety of optical networks for multicore processors. The high bandwidth and low latency features of photonic NoCs have led to the overall improvement in the system performance. However, there are very few proposals that discuss the usage of optical interconnects in Graphics Processor Units (GPUs). GPUs can also substantially gain from such novel technologies, because they need to provide significant computational throughput without further stressing their power budgets. The main shortcoming of optical networks is their high static power usage, because the lasers are turned on all the time by default, even when there is no traffic inside the chip, and thus sophisticated laser modulation schemes are required. Such modulation schemes base their decisions on an accurate prediction of network traffic in the future. In this article, we propose an energy-efficient and scalable optical interconnect for modern GPUs called GPUOPT that smartly creates an overlay network by dividing the symmetric multiprocessors (SMs) into clusters. It furthermore has separate sub-networks for coherence and non-coherence traffic. To further increase the throughput, we connect the off-chip memory with optical links as well. Subsequently, we show that traditional laser modulation schemes (for reducing static power consumption) that were designed for multicore processors are not that effective for GPUs. Hence, there was a need to create a bespoke scheme for predicting the laser power usage in GPUs. Using this set of techniques, we were able to improve the performance of a modern GPU by 45% as compared to a state-of-the-art electrical NoC. Moreover, as compared to competing optical NoCs for GPUs, our scheme reduces the laser power consumption by 67%, resulting in a net 65% reduction in ED 2 for a suite of Rodinia benchmarks.

High-performance frequency stabilization of ultraviolet diode lasers by using dichroic atomic vapor spectroscopy and transfer cavity**Project supported by the National Natural Science Foundation of China (Grant Nos. 11704408 and 91836106), the Beijing Natural Science Foundation, China (Grant No. Z180013), and the Joint Fund of the Ministry of Education, China (Grant No. 6141A020333xx).

We develop a high-performance ultraviolet (UV) frequency stabilization technique implemented directly on UV diode lasers by combining the dichroic atomic vapor laser lock and the resonant transfer cavity lock. As an example, we demonstrate a stable locking with measured frequency standard deviations of approximately 200 kHz and 300 kHz for 399 nm and 370 nm diode lasers in 20 min. We achieve a long-term frequency drift of no more than 1 MHz for the target 370 nm laser within an hour, which is further verified with fluorescence count rates of a single trapped 171Yb+ ion. We also find strong linear correlations between lock points and environmental factors such as temperature and atmospheric pressure. Our approach provides a simple and stable solution at a relatively low cost, and features flexible control, high feedback bandwidth and minimal power consumption of the target UV laser.

Energy Efficiency Analysis of Comb Source Carrier-Injection Ring-Based Silicon Photonic Link

Current electronic interconnections in high performance computing (HPC) systems are reaching their limit in supporting high data traffic demands. Dense wavelength-division multiplexed (DWDM) links have gained interest as they can potentially alleviate these interconnect bandwidth demands while also lowering the cost and energy consumption compared to traditional electronic links. In this article we present an analysis of a ring-based DWDM silicon photonic (SiP) link architecture with a comb laser source and p-i-n photodetectors. Specifically, we consider microring resonators (MRRs) with narrow bus waveguides and carrier-injection ring modulators. We propose a new method to select the optimal comb source setting to minimize the laser power consumption at a particular data rate. Additionally, we leverage power penalty models supported by measurements to estimate the effective received optical power at the receiver input of each of the DWDM channels which yields a bit error rate (BER) of $\text{10}^{-{\text{12}}}$ or lower. We show that the analyzed comb source has the lowest power consumption per channel for 24 consecutive lines. For these comb settings, the maximum channel data rate of non-return to zero on-off keying (NRZ-OOK) signals is 22 Gbps, and the minimum energy consumption is 3.28 $\frac{\text{pJ}}{\text{bit}}$ .

Optical Versus Electrical: Performance Evaluation of Network On-Chip Topologies for UWASN Manycore Processors

Optical network on chip (ONoC) has evolved as an innovative technology for on-chip interconnects that can fulfill the upcoming requirements of manycore processors used in UWASN. The objective of this paper is two-fold, first we assessed the performance of electrical and optical NoC mesh and torus topologies with 64 and 144 nodes. We explored the impact of different packet and network sizes on average latency and throughput of NoCs. Furthermore, we investigated the effect of application mapping on crosstalk noise, laser power consumption and SNR for optical mesh/torus architectures under real time benchmark applications. The experimental outcomes revealed that ONoC has advantages of improved average latency and improved throughput for large packet size. Second, we proposed a hybrid optical–electrical NoC topology based on multi write single read serpentine optical bus architecture aiming to minimize the communication latency and energy consumption. We present an optimized routing algorithm for the proposed topology that exploits the advantage of processing parallelism level to reduce latency in hybrid network. The proposed topology proved to be 48% and 53% efficient in latency, 12% and 17% higher in throughput and provides 54% and 23% reduction in energy consumption under uniform random and hotspot traffic patterns respectively as compared to other NoC architectures.

A Group-Based Laser Power Supply Scheme for Photonic Network on Chip

It is expected that the future multicore systems will significantly benefit from photonic interconnect technology because of its large bandwidth. However, the static power consumed by laser sources accounts for a large proportion of the overall power budget; thus, it has a negative impact on the performance of future photonic network on chip. In this paper, GLaP, a group-based static laser power supply approach is proposed. The communication backbone is investigated based on single-write-multiread crossbar. Generic laser power delivery and allocation architectures are proposed to match the bandwidths with the requirements of different nodes. The laser sources are shared across the network which enables significant reduction in laser power consumption. The evaluation results show that the laser power can be significantly saved compared with traditional laser supply schemes.

Towards Maximum Energy Efficiency in Nanophotonic Interconnects with Thermal-Aware On-Chip Laser Tuning

Nanophotonic is an emerging technology considered as one of the key solutions for future generation on-chip interconnects. However, silicon photonic devices are highly sensitive to temperature variation. Under a given chip activity, this leads to a lower laser efficiency and a drift of wavelengths of optical devices (on-chip lasers and microring resonators (MRs)), which results in a higher Bit Error Ratio (BER). In this paper, we propose to jointly tune the on-chip lasers and and MRs in order to align the wavelengths of the emitted signals with the resonant wavelengths of the MRs. Our method allows significant improvements of the power consumption with regard to the related methods, while meeting the BER requirement. Compared to methods for which laser tuning is not possible, results show that a combined tuning of laser and MRs leads to 53 percent energy reduction when the uniform chip activity decreases from 20 to 5 percent. BER-energy tradeoffs have been explored and allow strategies to be defined to minimize either the energy, or the BER. As a key result, we have shown that, under specific chip activities, increasing the laser power consumption allows both energy and BER to be improved. This trend has been observed for a MWSR channel interconnecting 12 interfaces.

Reducing Power Consumption of Lasers in Photonic NoCs through Application-Specific Mapping

To face the complex communication problems that arise as the number of on-chip components grows up, photonic networks-on-chip (NoCs) have been recently proposed to replace electronic interconnects. However, photonic NoCs lack efficient laser sources, possibly resulting in an inefficient or inoperable architecture. In this article, we introduce a methodology for the design space exploration of optical NoC mapping solutions, which automatically assigns IPs/cores to the network tiles such that the laser power consumption is minimized. The experimental evaluation shows average reductions of 34.7% and 27.3% in the power consumption compared to, respectively, application-oblivious and randomly mapped photonic NoCs, allowing improved energy efficiency.

An atom interferometer inside a hollow-core photonic crystal fiber.

Coherent interactions between electromagnetic and matter waves lie at the heart of quantum science and technology. However, the diffraction nature of light has limited the scalability of many atom-light-based quantum systems. We use the optical fields in a hollow-core photonic crystal fiber to spatially split, reflect, and recombine a coherent superposition state of free-falling 85Rb atoms to realize an inertia-sensitive atom interferometer. The interferometer operates over a diffraction-free distance, and the contrasts and phase shifts at different distances agree within one standard error. The integration of phase coherent photonic and quantum systems here shows great promise to advance the capability of atom interferometers in the field of precision measurement and quantum sensing with miniature design of apparatus and high efficiency of laser power consumption.

PROTON+

Optical Networks-on-Chip (ONoCs) are a promising technology to overcome the bottleneck of low bandwidth of electronic Networks-on-Chip. Recent research discusses power and performance benefits of ONoCs based on their system-level design, while layout effects are typically overlooked. As a consequence, laser power requirements are inaccurately computed from the logic scheme but do not consider the layout. In this article, we propose PROTON+, a fast tool for placement and routing of 3D ONoCs minimizing the total laser power. Using our tool, the required laser power of the system can be decreased by up to 94% compared to a state-of-the-art manually designed layout. In addition, with the help of our tool, we study the physical design space of ONoC topologies. For this purpose, topology synthesis methods (e.g., global connectivity and network partitioning) as well as different objective function weights are analyzed in order to minimize the maximum insertion loss and ultimately the system’s laser power consumption. For the first time, we study optimal positions of memory controllers. A comparison of our algorithm to a state-of-the-art placer for electronic circuits shows the need for a different set of tools custom-tailored for the particular requirements of optical interconnects.

Runtime Management of Laser Power in Silicon-Photonic Multibus NoC Architecture

Silicon-photonic links have been proposed to replace electrical links for global on-chip communication in future many-core processors. Silicon-photonic links have the advantage of lower data-dependent power and higher bandwidth density, but the high laser power can more than offset these advantages. We propose a solution to manage laser power of silicon-photonic network-on-chip (NoC) in many-core system. We present a silicon-photonic multibus NoC architecture between private L1 caches and distributed L2 cache banks which uses weighted time-division multiplexing to distribute the laser power across multiple buses based on the runtime variations in the bandwidth requirements within and across applications to maximize energy efficiency. The multibus NoC architecture also harnesses the opportunities to switch OFF laser sources at runtime, during low-bandwidth requirements, to reduce laser power consumption. Using detailed system-level simulations, we evaluate the multibus NoC architecture and runtime laser power management technique on a 64-core system running NAS parallel benchmark suite. The silicon-photonic multibus NoC architecture provides more than two times better performance than silicon-photonic Clos and butterfly NoC architectures, while consuming the same laser power. Using runtime laser power management technique, the average laser power is reduced by more than 49% with minimal impact on the system performance.

Adaptive crosshatch approach for the laminated object manufacturing (LOM) process

The waste material removal process of laminated object manufacturing (LOM), so-called 'decubing', is a labour-intensive and time-consuming work resulting from the commonly used uniform crosshatch setting. An adaptive crosshatch approach to improve working efficiency and alleviate the effort involved in the decubing process is developed. The working region is divided into two portions, the inner region and the outer region, by the proposed rectangle and original contour offset approaches. The fine crosshatch pattern is designated to the inner region based on the shape of the cross-section contour, and the rules to select crosshatches for different shapes are given. The outer region has a coarse crosshatch pattern, and it is an integer multiple of that of the inner region. The brick-layered effect in the overlap zone of the waste material is eliminated by the projection method. Experiments show that with the adaptive crosshatch approach there are four major advantages: saving laser power consumption, protecting the part from damage, improving machining efficiency and easier decubing.