The Experts below are selected from a list of 287322 Experts worldwide ranked by ideXlab platform
Jaeweon Jeong - One of the best experts on this subject based on the ideXlab platform.
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Energy Performance Comparison between Liquid-Desiccant-Assisted Air Conditioning System and Dedicated Outdoor Air System in Different Climatic Regions
MDPI AG, 2019Co-Authors: Su Liu, Jaeweon JeongAbstract:The main purpose of this research is to analyze and compare the Energy performance of two different novel air conditioning systems; one is a dedicated outdoor air system (DOAS) with a parallel system and the other is a heat-pump-integrated liquid-desiccant and evaporative-cooling-assisted 100% outdoor air system (HPLD-IDECOAS). It was assumed that office buildings served by each system were located in six cities representing four different climatic regions in China. The hourly thermal loads of the office buildings meeting the local building design codes of each selected city were predicted by the TRNSYS 18 software package. The hourly thermal load data were imported into the commercial engineering equation solver (EES) program to estimate the Operating Energy consumption of each system via detailed Energy simulations performed using valid system simulation models. The results show that the HPLD-IDECOAS has higher Energy-saving potential than the DOAS with a parallel system in climate regions with high humidity, whereas, in dry regions, the difference in Energy consumption between the two systems was not significant
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Energy Performance of Liquid Desiccant and Evaporative Cooling-Assisted 100% Outdoor Air Systems under Various Climatic Conditions
MDPI AG, 2018Co-Authors: Jaeweon JeongAbstract:The main purpose of this study is to evaluate the applicability of a liquid desiccant and evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) in six typical cities in China. The six cities are located in different climatic zones in China and are selected because they are comparable owing to the outdoor air conditions. Many studies have shown that the annual Operating Energy consumption of LD-IDECOAS is nearly half compared with the conventional variable air volume (VAV) system. Because the climate characteristics of the six selected cities were different, the appropriate mode of operation of the LD-IDECAOS was applied to each studied city, and Energy simulations were performed. Based on the design conditions of each region, the required cooling and heating loads were calculated for office buildings using transient system simulations (TRNSYS) 17, and the performance of the LD-IDECOAS and its Energy consumption were simulated with a commercial engineering equation solver (EES) program. Depending on the climate characteristics of each city, adequate modifications were evaluated with simulations in terms of Energy consumption. The proposed system was compared with the VAV system and the evaporative cooling assisted 100% outdoor air-conditioning system (IDECOAS) for detailed simulation results in the effort to evaluate the Energy-saving potential. Finally, the results show that the proposed system saves considerable Energy over conventional VAV systems and, in summer, the applications save even more Energy than IDECOAS. However, there is a slight difference between the different geographical regions in terms of the annual Operating Energy consumption. In summary, the proposed system can yield significant Energy-saving benefits in hot and humid regions whereas, in dry regions, the proposed system is more applicable in the summer. Consequently, LD-IDECOAS can be adopted for different climatic zones as a heating, ventilating, and air-conditioning (HVAC) system by introducing 100% outdoor air
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primary Energy savings in desiccant and evaporative cooling assisted 100 outdoor air system combined with a fuel cell
Applied Energy, 2016Co-Authors: Min-hwi Kim, Joonyoung Park, Hae Won Dong, Jaeweon JeongAbstract:Abstract The main purpose of this study involved investigating the primary Energy saving potential of a liquid desiccant and evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) integrated with a proton exchange membrane fuel cell (PEMFC). During the cooling season, the heat produced by the PEMFC was used to regenerate a weak desiccant solution, and the electricity generated was used to operate the LD-IDECOAS. A pilot LD-IDECOAS powered by a PEMFC was installed and operated in an office space to experimentally verify the annual Operating Energy savings of the proposed system. The findings indicated that the heat reclaimed from the PEMFC saved 42% of the desiccant solution regenerating Energy when compared to that in the case of a conventional gas-fired water heater. The results also suggested that the LD-IDECOAS combined with a PEMFC consumed 21% less primary Energy when compared with that of a system powered by grid electricity and a conventional gas-fired water heater.
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Operating Energy savings in a liquid desiccant and dew point evaporative cooling assisted 100 outdoor air system
Energy and Buildings, 2016Co-Authors: Jaeweon JeongAbstract:Abstract The main purpose of this study is to develop a liquid desiccant and dew point evaporative cooling-assisted 100% outdoor air system (LDEOS), and to evaluate its Energy saving potentials. In recent years, non-vapor-compression air conditioning systems are becoming available without compromising Energy efficiency, thermal comfort, and ventilation requirements. A quasi-dynamic simulation model of LDEOS including a dew point evaporative cooler model was developed to compare the Energy performance of LDEOS against a typical variable air volume (VAV) system. A sequence of operation for LDEOS was also proposed. Simulation results showed that LDEOS could save 12% of primary Energy compared to a conventional VAV, while 100% of outdoor air was conditioned and delivered to the space without using vapor compression technology.
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retrofit of a liquid desiccant and evaporative cooling assisted 100 outdoor air system for enhancing Energy saving potential
Applied Thermal Engineering, 2016Co-Authors: Min-hwi Kim, Dongseop Yoon, Huijeong Kim, Jaeweon JeongAbstract:Abstract The objective of this research is to retrofit a liquid desiccant (LD) and indirect/direct evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) to enhance its Operating Energy saving potential. Two retrofit cases of existing LD-IDECOAS have been considered. The first case involves replacing the indirect and direct evaporative coolers with an M-cycle or a dew-point indirect evaporative cooler (i.e., Case 1), and the other one involves adding an enthalpy exchanger before the LD unit of the system in case 1 (i.e., Case 2). By conducting detailed Energy simulations for each retrofit case, the improvements in Operating Energy saving and the coefficient of performance (COP) over the existing LD-IDECOAS were quantitatively evaluated. The results showed that case 1 might provide enhancement in cooling capacity and thermal COP; however, the heating Energy consumption for regenerating the desiccant solution increased with the higher process airflow rate when compared to the existing LD-IDECOAS. It was also found that the cooling capacity, thermal COP, and primary COP could be improved by adding a membrane enthalpy exchanger, as done in case 2, without any significant increase in the heating Energy consumption for regenerating the desiccant solution.
Min-hwi Kim - One of the best experts on this subject based on the ideXlab platform.
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operational Energy saving potential of thermal effluent source heat pump system for greenhouse heating in jeju
International Journal of Air-conditioning and Refrigeration, 2017Co-Authors: Min-hwi Kim, Dongwon Lee, Rin Yun, Jaehyeok HeoAbstract:Massive thermal effluent Energy from power plant is mostly released to the sea, and only a little is used for fishing culture and agriculture in South Korea. The thermal effluent from the power plant can be an efficient heat source of the heat pump system to provide heating Energy for the greenhouse, but Energy loss and pump power by long distance pipeline installation from a power plant to the greenhouse should be considered. In this paper, an operational Energy saving potential of a thermal effluent source heat pump system for the greenhouse heating was investigated. For the estimation of thermal load, three cases of greenhouse were categorized, and the thermal performance and Operating Energy consumption during the heating season were compared with those of a conventional ground source heat pump (GSHP) system. The model for heat pump system was newly derived to estimate the Energy performance of the proposed system, and then detailed simulations for each system under three cases of greenhouse were conducted. The results showed that the operational Energy of the proposed system can be saved by 17–20% than that of the conventional GSHP system.
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primary Energy savings in desiccant and evaporative cooling assisted 100 outdoor air system combined with a fuel cell
Applied Energy, 2016Co-Authors: Min-hwi Kim, Joonyoung Park, Hae Won Dong, Jaeweon JeongAbstract:Abstract The main purpose of this study involved investigating the primary Energy saving potential of a liquid desiccant and evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) integrated with a proton exchange membrane fuel cell (PEMFC). During the cooling season, the heat produced by the PEMFC was used to regenerate a weak desiccant solution, and the electricity generated was used to operate the LD-IDECOAS. A pilot LD-IDECOAS powered by a PEMFC was installed and operated in an office space to experimentally verify the annual Operating Energy savings of the proposed system. The findings indicated that the heat reclaimed from the PEMFC saved 42% of the desiccant solution regenerating Energy when compared to that in the case of a conventional gas-fired water heater. The results also suggested that the LD-IDECOAS combined with a PEMFC consumed 21% less primary Energy when compared with that of a system powered by grid electricity and a conventional gas-fired water heater.
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retrofit of a liquid desiccant and evaporative cooling assisted 100 outdoor air system for enhancing Energy saving potential
Applied Thermal Engineering, 2016Co-Authors: Min-hwi Kim, Dongseop Yoon, Huijeong Kim, Jaeweon JeongAbstract:Abstract The objective of this research is to retrofit a liquid desiccant (LD) and indirect/direct evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) to enhance its Operating Energy saving potential. Two retrofit cases of existing LD-IDECOAS have been considered. The first case involves replacing the indirect and direct evaporative coolers with an M-cycle or a dew-point indirect evaporative cooler (i.e., Case 1), and the other one involves adding an enthalpy exchanger before the LD unit of the system in case 1 (i.e., Case 2). By conducting detailed Energy simulations for each retrofit case, the improvements in Operating Energy saving and the coefficient of performance (COP) over the existing LD-IDECOAS were quantitatively evaluated. The results showed that case 1 might provide enhancement in cooling capacity and thermal COP; however, the heating Energy consumption for regenerating the desiccant solution increased with the higher process airflow rate when compared to the existing LD-IDECOAS. It was also found that the cooling capacity, thermal COP, and primary COP could be improved by adding a membrane enthalpy exchanger, as done in case 2, without any significant increase in the heating Energy consumption for regenerating the desiccant solution.
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Energy conservation benefit of water side free cooling in a liquid desiccant and evaporative cooling assisted 100 outdoor air system
Energy and Buildings, 2015Co-Authors: Min-hwi Kim, Joonyoung Park, Sang-woo Ham, Jaeweon JeongAbstract:Abstract The main purpose of this research was to experimentally investigate a liquid desiccant and evaporative cooling-assisted 100% outdoor air system. The proposed system was integrated with water-side free cooling in the desiccant solution and process air cooling to enhance its Energy performance. The experimental results show that the required cooling water temperature for the desiccant solution is higher than the conventional cooling water supply temperature; that is, approximately 22–27 °C. Consequently, water-side free cooling was applied to produce the cooling water for the desiccant solution. The operation of the proposed system with the water-side economizer showed a 40–70% effectiveness of the indirect evaporative cooler, while that of the direct evaporative cooler was greater than 95%, and the supply air temperature ranged between 17 and 20 °C. The Energy coefficient of performance (COP) of water-side free cooling applied to cool the desiccant solution was 8–17, whereas that of the conventional air-cooled chiller was 1–3. Economic consideration indicated that the Operating Energy savings might offset the penalty in the initial cost of the proposed system.
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practical thermal performance correlations for a wet coil indirect evaporative cooler
Energy and Buildings, 2015Co-Authors: Min-hwi Kim, Duksoo Jeong, Jaeweon JeongAbstract:Abstract The objective of this research was to develop practical models for predicting the thermal performance of a wet-coil indirect evaporative cooler (IEC). Through statistical analysis of cooling and heat exchange effectiveness data generated by a simple ɛ − NTU (number of transfer units) method, simplified models returning the thermal performance of a wet-coil IEC were developed. Linear regression equations were derived as a function of the major design parameters and interactions that strongly affected the wet-coil IEC's performance. A pilot wet-coil IEC unit was built to validate the proposed models. Effectiveness data were obtained under a controlled range of Operating conditions in an environmental chamber. Then, the Energy-saving potential achievable by integrating a wet-coil IEC into a conventional variable air volume (VAV) system for pre-conditioning the outdoor air intake was quantitatively evaluated. The experimental results showed that more than 75% cooling effectiveness and 59% heat reclaim effectiveness could be achieved under wet and dry Operating conditions, respectively. The experimental data acquired using the pilot unit agreed well with the thermal effectiveness predicted by the proposed models. Consequently, the VAV system integrated with the wet-coil IEC showed more than 45% reduced annual Operating Energy consumption compared with the conventional VAV system.
Manish K. Dixit - One of the best experts on this subject based on the ideXlab platform.
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evaluating the impact of Operating Energy reduction measures on embodied Energy
Energy and Buildings, 2020Co-Authors: Varusha Venkatraj, Manish K. Dixit, Wei Yan, Sarel LavyAbstract:Abstract Annually, 48% of the global Energy is used by buildings in their construction, operation, and maintenance, causing significant damage to the environment due to the resulting greenhouse gas emissions. During their life cycles, buildings use Energy in the form of embodied Energy (EE) and Operating Energy (OE). In a conventional building, EE accounts for 10–20% of a building’s life cycle Energy (LCE), while OE accounts for 80–90%. As a result, the building sector has taken several measures to reduce OE in buildings. These OE reducing measures fail to account for the subsequent increase in EE and might cause an increase in the building’s overall LCE. A systematic review of the literature shows limited research that comprehensively evaluates the impact of design measures aimed at OE reduction on EE for different construction assemblies. In this study, we quantify and compare trade-offs on EE demand, caused by OE reduction measures for eight different building wall assemblies across four climatic zones within the United States. The EE and OE demands of the ASHRAE 90.1–2016 benchmark model and its variations were computed using Tally™ and Autodesk® Green Building Studio® (GBS), respectively. The results helped us determine the EE factor (EE spent per unit of OE savings) for different OE reduction measures. Although the calculated EE factors vary across different climatic zones and construction assemblies, these factors show significant EE costs for different OE reduction measures. This knowledge could help inform the design of evolutionary and deep/machine learning-based algorithms to assess and optimize building Energy use.
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life cycle recurrent embodied Energy calculation of buildings a review
Journal of Cleaner Production, 2019Co-Authors: Manish K. DixitAbstract:Abstract Buildings use approximately 48% of global Energy each year in their construction and operation as embodied and Operating Energy. The embodied Energy is used directly through onsite and offsite construction and related processes, and indirectly through the use of materials and equipment. The embodied Energy used in a building's construction is called initial embodied Energy (IEE), whereas the Energy embodied in the recurring processes of maintenance, repair, and replacement is termed recurrent embodied Energy (REE). To effectively optimize a building's life cycle embodied Energy, both the REE and IEE must be evaluated collectively. However, a building's REE depends on multiple parameters, which can cause significant variations of REE results across studies. A thorough investigation of parameters specific to REE calculation is currently lacking. The REE parameters may introduce significant uncertainties in the life cycle embodied Energy calculations. In this paper, we perform a systematic review of literature to identify key parameters affecting REE calculations. We also propose a framework to identify and quantify the uncertainties resulting from these parameters. The findings of this study will help streamline the process of life cycle embodied Energy calculation.
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life cycle embodied Energy analysis of residential buildings a review of literature to investigate embodied Energy parameters
Renewable & Sustainable Energy Reviews, 2017Co-Authors: Manish K. DixitAbstract:Approximately half of the annual global Energy supply is consumed in constructing, Operating, and maintaining buildings. Because most of this Energy comes from fossil fuels, it also contributes greatly to annual carbon emissions. When constructing a building, embodied Energy is consumed through construction materials, building products, and construction processes along with any transportation, administration, and management involved. Operating Energy is used in space conditioning, heating, lighting, and powering building appliances. In order to effectively reduce the carbon footprint of buildings, a comprehensive reduction in both embodied and Operating Energy is needed. Studies so far have focused on reducing either embodied or Operating Energy in isolation without realizing the trade-off that exists between them. Also, building Energy research has concentrated more on Operating Energy than embodied Energy, and as a result, the Operating Energy of buildings is gradually decreasing. Due to a variety of issues, however, few efforts have been undertaken to comprehensively minimize embodied Energy.
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embodied Energy analysis of building materials an improved io based hybrid method using sectoral disaggregation
Energy, 2017Co-Authors: Manish K. DixitAbstract:Buildings consume approximately half of the annual Energy supply of the United States in their construction and operation. To effectively decrease this extensive Energy footprint, both embodied and Operating Energy must be quantified and optimized. Although validated standard methods are available to compute Operating Energy, quantifying embodied Energy is still complicated and inconsistent. Among the available embodied Energy calculation methods, an input-output-based hybrid (IOH) method has the potential to offer a more complete calculation. However, its calculation lacks specificity and reliability, which can be improved using suggestions provided by literature. Studies across the globe have proposed techniques such as sectoral disaggregation to enhance not only the specificity and reliability, but also the completeness, of an IOH method.
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identification of parameters for embodied Energy measurement a literature review
Energy and Buildings, 2010Co-Authors: Manish K. Dixit, Jose L Fernandezsolis, Sarel Lavy, C. CulpAbstract:The building construction industry consumes a large amount of resources and Energy and, owing to current global population growth trends, this situation is projected to deteriorate in the near future. Buildings consume approximately 40 percent of total global Energy: during the construction phase in the form of embodied Energy and during the operation phase as Operating Energy. Embodied Energy is expended in the processes of building material production (mining and manufacture), on-site delivery, construction and assembly on-site, renovation and final demolition. Recent studies have considered the significance of embodied Energy inherent in building materials, with a specific focus on this fraction of sequestered Energy. Current interpretations of embodied Energy are quite unclear and vary greatly, and embodied Energy databases suffer from problems of variation and incomparability. Furthermore, there is no reliable template, standard or protocol regarding embodied Energy computations that could address these problems in embodied Energy inventories. This paper focuses on the analysis of existing literature in order to identify differing parameters so that development of a consistent and comparable database can be facilitated.
Joonyoung Park - One of the best experts on this subject based on the ideXlab platform.
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primary Energy savings in desiccant and evaporative cooling assisted 100 outdoor air system combined with a fuel cell
Applied Energy, 2016Co-Authors: Min-hwi Kim, Joonyoung Park, Hae Won Dong, Jaeweon JeongAbstract:Abstract The main purpose of this study involved investigating the primary Energy saving potential of a liquid desiccant and evaporative cooling-assisted 100% outdoor air system (LD-IDECOAS) integrated with a proton exchange membrane fuel cell (PEMFC). During the cooling season, the heat produced by the PEMFC was used to regenerate a weak desiccant solution, and the electricity generated was used to operate the LD-IDECOAS. A pilot LD-IDECOAS powered by a PEMFC was installed and operated in an office space to experimentally verify the annual Operating Energy savings of the proposed system. The findings indicated that the heat reclaimed from the PEMFC saved 42% of the desiccant solution regenerating Energy when compared to that in the case of a conventional gas-fired water heater. The results also suggested that the LD-IDECOAS combined with a PEMFC consumed 21% less primary Energy when compared with that of a system powered by grid electricity and a conventional gas-fired water heater.
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Energy conservation benefit of water side free cooling in a liquid desiccant and evaporative cooling assisted 100 outdoor air system
Energy and Buildings, 2015Co-Authors: Min-hwi Kim, Joonyoung Park, Sang-woo Ham, Jaeweon JeongAbstract:Abstract The main purpose of this research was to experimentally investigate a liquid desiccant and evaporative cooling-assisted 100% outdoor air system. The proposed system was integrated with water-side free cooling in the desiccant solution and process air cooling to enhance its Energy performance. The experimental results show that the required cooling water temperature for the desiccant solution is higher than the conventional cooling water supply temperature; that is, approximately 22–27 °C. Consequently, water-side free cooling was applied to produce the cooling water for the desiccant solution. The operation of the proposed system with the water-side economizer showed a 40–70% effectiveness of the indirect evaporative cooler, while that of the direct evaporative cooler was greater than 95%, and the supply air temperature ranged between 17 and 20 °C. The Energy coefficient of performance (COP) of water-side free cooling applied to cool the desiccant solution was 8–17, whereas that of the conventional air-cooled chiller was 1–3. Economic consideration indicated that the Operating Energy savings might offset the penalty in the initial cost of the proposed system.
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application of desiccant systems for improving the performance of an evaporative cooling assisted 100 outdoor air system in hot and humid climates
Journal of Building Performance Simulation, 2015Co-Authors: Min-hwi Kim, Junseok Park, Joonyoung Park, Jaeweon JeongAbstract:The purpose of this study was to enhance the Energy-saving potential of an indirect and direct evaporative cooling-assisted 100% outdoor air system (IDECOAS) by integrating it with either a solid or liquid desiccant system. The desiccant system can be installed either at the scavenger air side of the indirect evaporative cooler (IEC) to enhance its effectiveness or at the primary air side of the IEC to reduce the latent load of outdoor air. The Operating Energy consumption affected by the location and type of the desiccant unit integrated with IDECOAS was simulated under three different hot and humid climates using TRNSYS 17 integrated with commercial equation solver programme. And then, the most Energy-conservative configuration was selected for each climate zone as the proposed system. The simulation results showed that configurations with the desiccant dehumidification unit located upstream of the IDECOAS consume 76–85% less cooling coil Energy than those with the desiccant unit located downstream of t...
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annual Operating Energy savings of liquid desiccant and evaporative cooling assisted 100 outdoor air system
Energy and Buildings, 2014Co-Authors: Joonyoung Park, Minki Sung, Anseop Choi, Jaeweon JeongAbstract:a b s t r a c t The purpose of this research is to investigate the annual Operating Energy performance of a desiccant and evaporative-cooling-assisted 100% outdoor air system. The seasonal mode of operation of the proposed system is also suggested and used for estimating the Energy saving potentials. The TRNSYS 16 program integrated with a commercial equation solver is used for the Energy simulation of the proposed system, and then two existing air handling alternatives: a conventional variable air volume (VAV) system and an existing evaporative-cooling-assisted system are compared with the proposed system. The proposed system shows Operating Energy savings of 82% over the conventional VAV system dur- ing the summer, and 54% and 37% in the winter and the intermediate season operations, respectively. Ultimately, the proposed system provides 68% annual Operating Energy saving over the conventional VAV system, and 23% savings compared to the established evaporative-cooling-assisted system. It is also found that the extreme Energy benefit can be obtained by enhancing the evaporative cooling effects using the liquid desiccant (LD) unit. The Operating Energy saving of the LD unit can be achieved by applying the water-side free cooling and the solar thermal system. © 2014 Elsevier B.V. All rights reserved.
Takaaki Kakitsuka - One of the best experts on this subject based on the ideXlab platform.
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low Operating Energy directly modulated lasers for short distance optical interconnects
Advances in Optics and Photonics, 2018Co-Authors: Shinji Matsuo, Takaaki KakitsukaAbstract:We review recent developments in directly modulated lasers (DMLs) with low Operating Energy for datacom and computercom applications. Key issues are their Operating Energy and the cost for employing them in these applications. To decrease the Operating Energy, it is important to reduce the active volume of the laser while maintaining the cavity Q-factor or photon lifetime in the cavity. Therefore, how to achieve high-reflectivity mirrors has been the main challenge in reducing the Operating Energy. In terms of the required output power from the lasers, the required input power into the photodetector and the transmission distance determine the lower limit of laser active volume. Therefore, the Operating Energy and output power are in a trade-off relationship. In designing the lasers, the cavity volume, quantum well number, and optical confinement factor are critical parameters. For reducing the cost, it is important to fabricate a large-scale photonic integrated circuit (PIC) comprising DMLs, an optical multiplexer, and monitor photodetectors because the lower assembly cost reduces the overall cost. In this context, silicon (Si) photonics technology plays a key role in fabricating large-scale PICs with low cost, and heterogeneous integration of DMLs and Si photonics devices has attracted much attention. We will describe fabrication technologies for heterogeneous integration and experimental results for DMLs on a Si substrate.
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heterogeneously integrated membrane lasers on si substrate for low Operating Energy optical links
IEEE Journal of Selected Topics in Quantum Electronics, 2018Co-Authors: Takuro Fujii, Nikolaospanteleimon Diamantopoulos, Hidetaka Nishi, Ryo Nakao, Koji Takeda, Koichi Hasebe, Takaaki Kakitsuka, Erina Kanno, Shinji MatsuoAbstract:High demand exists for low Operating Energy optical links that use wavelength division multiplexing technologies in datacenter networks. Thus, we fabricate a directly modulated membrane distributed-reflector laser with low Operating Energy on a thermally oxidized silicon (Si) substrate. Because we use epitaxial growth to bury an active region on a directly bonded InP-based membrane, it needs to be kept within a critical thickness, which is related to the growth temperature and the thermal expansion coefficients of materials. In previous studies, we used 250-nm-thick structures, causing relatively large series resistance that limited device performance on such aspects as Energy cost and output power. In this study, we increase the III–V membrane thickness to 350 nm, which is close to the calculated critical thicknesses. We achieve the same high crystal quality of multiquantum-wells found in our previous studies. The fabricated laser shows a differential resistance of 72 Ω and thermal resistance of 982 K/W. Thanks to a reduction in bias voltage, the laser can be directly modulated at 25.8 Gbit/s with an Energy cost of 97 fJ/bit. In addition, due to a reduction in heat generation, direct modulation with a 50-Gbit/s non return to zero signal is demonstrated by increasing bias current up to 10 mA.
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si nanowire waveguide coupled current driven photonic crystal lasers
European Quantum Electronics Conference, 2017Co-Authors: Koji Takeda, Hidetaka Nishi, Takuro Fujii, Akihiko Shinya, Tai Tsuchizawa, Eiichi Kuramochi, Masaya Notomi, Koichi Hasebe, Takaaki Kakitsuka, Shinji MatsuoAbstract:Short distance optical communication is required to reduce power consumption of ICT systems and continuously improve performance of datacentres and HPCs [1]. Reduced Energy consumption and increased bandwidth density [2-3] are required to develop optical interconnects between chips and on chips. Therefore, lasers and detectors with ultra-low Operating Energy have to be connected by Si nanowire waveguides. In this context, we have developed photonic-crystal (PhC) lasers to reduce Energy consumption [4]. The unique feature of our PhC lasers is that we use wavelength-scale small buried heterostructures (BH) embedded in line-defect PhC to form cavities. We call our lasers lambda-scale embedded active-region photonic-crystal (LEAP) lasers. In this paper, we report the first continuous-wave (CW) operation of LEAP lasers coupled to Si waveguides.
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ultralow Operating Energy electrically driven photonic crystal lasers
IEEE Journal of Selected Topics in Quantum Electronics, 2013Co-Authors: Shinji Matsuo, Koji Takeda, Akihiko Shinya, Masaya Notomi, Koichi Hasebe, T Sato, Kengo Nozaki, Hideaki Taniyama, Takaaki KakitsukaAbstract:The introduction of the photonic crystal (PhC) wavelength-scale cavity as a laser cavity enables us to obtain both ultralow threshold current and Operating Energy. These parameters are essential when using the transmitters in chip-to-chip and on-chip interconnections. To improve the device performance, we employ an ultracompact embedded active region that we call a lambda-scale embedded active-region PhC laser or LEAP laser. We have developed an electrically driven LEAP laser, which operates under room-temperature continuous-wave conditions. To fabricate the electrically driven LEAP laser, we used Zn thermal diffusion and Si ion implantation, respectively, for p-type and n-type doping in an undoped InP layer. However, with previous fabricated devices there was a large leakage current through the substrate and the threshold current was 0.39 mA, which is larger than the expected threshold obtained by optical pumping. To reduce the leakage current, we propose using an InAlAs sacrificial laser instead of an InGaAs layer. The leakage current path through the substrate is effectively suppressed, and as a result, the threshold current is reduced to 7.8 μA, which is the lowest threshold current reported for any laser. Furthermore, the LEAP laser operates at up to 95 °C by using an InGaAlAs-based multiple quantum well structure. We also describe the dynamic characteristics of the laser. The LEAP laser exhibits a maximum 3-dB bandwidth of 16.2 GHz and the modulation current efficiency factor is 53.8 GHz/mA0.5 or 1.7 GHz/μA0.5, which is four times that of a vertical cavity surface-emitting laser. The device is directly modulated by a 12.5-Gb/s nonreturn-to-zero signal with a bias voltage of 1.6 V and a bias current of 109 μA, resulting in an Energy cost of 14.0 fJ/b. This is the smallest Operating Energy for any laser. These results indicate that the LEAP laser is highly suitable for use as a transmitter in computercom applications.
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all optical on chip bit memory based on ultra high q ingaasp photonic crystal
Optics Express, 2008Co-Authors: Akihiko Shinya, Eiichi Kuramochi, Takaaki Kakitsuka, Shinji Matsuo, Takasumi Tanabe, Tomonari Sato, Masaya NotomiAbstract:We demonstrate all-optical bit memory operation with photonic crystal (PhC) nanocavities based on an InGaAsP substrate with a band gap at a wavelength of about 1.3 µm. The optical bistability is based on a refractive index modulation caused by carrier-plasma dispersion. The Operating Energy required for switching is only 30 fJ, and the minimum optical bias power for bistability is 40 µW, which is about one hundred times less than that required for laser based bistable memories.