Wavelength tunable and directly modulated distributed Bragg reflector （DBR） lasers with butt-joint technology are designed, fabricated and characterized. The DBR laser consists of a gain section and a DBR section. T...Wavelength tunable and directly modulated distributed Bragg reflector （DBR） lasers with butt-joint technology are designed, fabricated and characterized. The DBR laser consists of a gain section and a DBR section. To increase the electrical isolation between the gain section and the DBR section, parts of a p-doped material in the isolation region are etched off selectively. Over 2kΩ isolation resistance is realized ultimately without the need of ion implantation, which simplifies the fabrication process. The laser exhibits high speed modulation with a large tunable range. The 3dB direct modulation bandwidth of the device is over 8GHz in a 12nm tunable range. This widely tunable DBR laser with the simple structure is promising as a colorless light source for the next-generation time and wavelength division multiplexed passive optical network （TWDM-PON） systems.展开更多
Compared with a conventional single section two-phase closed thermosyphon （TPCT） wellbore, a two-section TPCT wellbore has better heat transfer performance, which may improve the temperature distribution of fluid in...Compared with a conventional single section two-phase closed thermosyphon （TPCT） wellbore, a two-section TPCT wellbore has better heat transfer performance, which may improve the temperature distribution of fluid in wellbores, increase the temperature of fluid in wellheads and even more effectively reduce the failure rate of conventional TPCT wellbores. Heat transfer performance of two-section TPCT wellbores is affected by working medium, combination mode and oil flow rate. Different working media are introduced into the upper and lower TPCTs, which may achieve a better match between the working medium and the temperature field in the wellbores. Interdependence exists between the combination mode and the flow rate of the oil, which affects the heat transfer performance of a two-section TPCT wellbore. The experimental results show that a two-section TPCT wellbore, with equal upper and lower TPCTs respectively filled with Freon and methanol, has the best heat transfer performance when the oil flow rate is 200 L/h.展开更多
RSOA被认为是实现无源光网络PON中ONU无色化的一种重要的光学器件,但常见的RSOA的调制带宽往往只有1.5GHz左右,严重制约了PON系统的上行链路信号带宽。文章提出了两种有效提高RSOA调制带宽方案:使用光带通滤波器或者SOA与RSOA级联的均...RSOA被认为是实现无源光网络PON中ONU无色化的一种重要的光学器件,但常见的RSOA的调制带宽往往只有1.5GHz左右,严重制约了PON系统的上行链路信号带宽。文章提出了两种有效提高RSOA调制带宽方案:使用光带通滤波器或者SOA与RSOA级联的均衡原理,提高上行信号调制带宽和系统功率预算。通过深入的数学模型分析和大量的相关实验,验证了这两种方案的正确性和可行性,同时实验结果表明使用光带通滤波器或者SOA可以使RSOA调制带宽分别展宽0.15 GHz和0.3GHz,并将功率预算分别提高12 d B和17d B。展开更多
In this paper, we overview the principle of Orthogonal Frequency Division Multiplexing Passive Optical Network （OFDM-PON） systems, with a particular focus on upstream architectures capable of achieving 10Gbit/s colo...In this paper, we overview the principle of Orthogonal Frequency Division Multiplexing Passive Optical Network （OFDM-PON） systems, with a particular focus on upstream architectures capable of achieving 10Gbit/s colorless upstream transmission using Reflective Semiconductor Optical Amplifier （RSOA）. We propose an architecture of RSOA based OFDM-PON which can achieve 10Gbit/s upstream transmission over a single wavelength. A novel Dynamic Subcarrier Assignment （DSA） algorithm is also proposed to support my architecture, namely Service based Polling in Pipeline （SPP） dynamic subcarrier algorithm. A simulation was conducted to study the performance of SPP algorithm. Compared with the traditional dynamic bandwidth allocation algorithms, service based polling meets the quality of in pipeline algorithm service requirements excellently, and adapts orthogonal frequency division multiplexing passive optical network better with higher bandwidth efficiency and lower algorithm complexity.展开更多
基金Supported by the National Key Project under Grant No 2016YFB0402301the National High Technology Research and Development Program of China under Grant No 2013AA014502the National Natural Science Foundation of China under Grant Nos 61635010,61320106013,61474112,61321063 and 61274071
文摘Wavelength tunable and directly modulated distributed Bragg reflector （DBR） lasers with butt-joint technology are designed, fabricated and characterized. The DBR laser consists of a gain section and a DBR section. To increase the electrical isolation between the gain section and the DBR section, parts of a p-doped material in the isolation region are etched off selectively. Over 2kΩ isolation resistance is realized ultimately without the need of ion implantation, which simplifies the fabrication process. The laser exhibits high speed modulation with a large tunable range. The 3dB direct modulation bandwidth of the device is over 8GHz in a 12nm tunable range. This widely tunable DBR laser with the simple structure is promising as a colorless light source for the next-generation time and wavelength division multiplexed passive optical network （TWDM-PON） systems.
基金the financial support from the National Natural Science Foundation of China (No. 50674096)PetroChina Scientific & Technological Risk Innovation Project (No. 060511-2-1)
文摘Compared with a conventional single section two-phase closed thermosyphon （TPCT） wellbore, a two-section TPCT wellbore has better heat transfer performance, which may improve the temperature distribution of fluid in wellbores, increase the temperature of fluid in wellheads and even more effectively reduce the failure rate of conventional TPCT wellbores. Heat transfer performance of two-section TPCT wellbores is affected by working medium, combination mode and oil flow rate. Different working media are introduced into the upper and lower TPCTs, which may achieve a better match between the working medium and the temperature field in the wellbores. Interdependence exists between the combination mode and the flow rate of the oil, which affects the heat transfer performance of a two-section TPCT wellbore. The experimental results show that a two-section TPCT wellbore, with equal upper and lower TPCTs respectively filled with Freon and methanol, has the best heat transfer performance when the oil flow rate is 200 L/h.
文摘RSOA被认为是实现无源光网络PON中ONU无色化的一种重要的光学器件,但常见的RSOA的调制带宽往往只有1.5GHz左右,严重制约了PON系统的上行链路信号带宽。文章提出了两种有效提高RSOA调制带宽方案:使用光带通滤波器或者SOA与RSOA级联的均衡原理,提高上行信号调制带宽和系统功率预算。通过深入的数学模型分析和大量的相关实验,验证了这两种方案的正确性和可行性,同时实验结果表明使用光带通滤波器或者SOA可以使RSOA调制带宽分别展宽0.15 GHz和0.3GHz,并将功率预算分别提高12 d B和17d B。
基金supported by NSFC Project No.61372119863 Program No.2011AA01A104Doctoral Scientific Fund Project of the Ministry of Education of China(No.20120005110010)
文摘In this paper, we overview the principle of Orthogonal Frequency Division Multiplexing Passive Optical Network （OFDM-PON） systems, with a particular focus on upstream architectures capable of achieving 10Gbit/s colorless upstream transmission using Reflective Semiconductor Optical Amplifier （RSOA）. We propose an architecture of RSOA based OFDM-PON which can achieve 10Gbit/s upstream transmission over a single wavelength. A novel Dynamic Subcarrier Assignment （DSA） algorithm is also proposed to support my architecture, namely Service based Polling in Pipeline （SPP） dynamic subcarrier algorithm. A simulation was conducted to study the performance of SPP algorithm. Compared with the traditional dynamic bandwidth allocation algorithms, service based polling meets the quality of in pipeline algorithm service requirements excellently, and adapts orthogonal frequency division multiplexing passive optical network better with higher bandwidth efficiency and lower algorithm complexity.
