共查询到20条相似文献,搜索用时 15 毫秒
1.
We transfer an optical frequency over 251 km of optical fiber with a residual instability of 6x10(-19) at 100 s. This instability and the associated timing jitter are limited fundamentally by the noise on the optical fiber and the link length. We give a simple expression for calculating the achievable instability and jitter over a fiber link. Transfer of optical stability over this long distance requires a highly coherent optical source, provided here by a cw fiber laser locked to a high finesse optical cavity. A sufficient optical carrier signal is delivered to the remote fiber end by incorporating two-way, in-line erbium-doped fiber amplifiers to balance the 62 dB link loss. 相似文献
2.
Wook Jae Yoo Jeong Ki Seo Sang Hun Shin Ki-Tek Han Dayeong Jeon Kyoung Won Jang Hyeok In Sim Bongsoo Lee Jang-Yeon Park 《Optical Review》2013,20(2):173-177
In this study, a fiber-optic dosimeter (FOD) was developed to measure entrance surface dose (ESD) in diagnostic radiology. We measured the scintillating lights in order to obtain ESDs, which changed with the various exposure parameters of a digital radiography (DR) system, such as tube potential, current-time product, focus-surface distance (FSD), and field size, using the fabricated FOD system. From the experimental results, the output light signals of the FOD were similar to the ESDs of the conventional semiconductor dosimeter. In conclusion, we characterized the measured ESDs as functions of exposure parameters by using two different types of dosimeters and demonstrated that the proposed FOD using a plastic scintillating fiber and a plastic optical fiber (POF) makes it possible to measure ESDs in the energy range of diagnostic radiology. From the results of this study, it is anticipated that the FOD will be a useful dosimeter in low-energy photon applications including diagnostic radiology. 相似文献
3.
Optical pulse compression using high-order dispersion compensation is proposed and theoretically analyzed. Firstly, the required
dispersion profile for the high-order dispersion compensation is derived, according to the linear chirp and the nonlinear
chirp of a phase-modulated continuous-wave (CW) laser source. With the use of the high-order dispersion compensation, such
as the combination compensation of the second order dispersion (SOD) and the fourth order dispersion (FOD), an efficient pulse
compression having a less time-bandwidth product and a greater peak power is realized. A sampled fiber Bragg grating (FBG)
with both the SOD and the FOD is then designed using the equivalent chirp and the reconstruction algorithm. Finally, in the
numerical simulation an optical pulse with a time-bandwidth product of 0.79 is generated via high-order dispersion compensation
that is performed by using the sampled FBG. 相似文献
4.
Lax pair and vector semi-rational nonautonomous rogue waves for a coupled time-dependent coefficient fourth-order nonlinear Schrodinger system in an inhomogeneous optical fiber 下载免费PDF全文
Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves. 相似文献
5.
Lax pair and vector semi-rational nonautonomous rogue waves for a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system in an inhomogeneous optical fiber 下载免费PDF全文
《中国物理 B》2020,(3)
Optical fibers are seen in the optical sensing and optical fiber communication. Simultaneous propagation of optical pulses in an inhomogeneous optical fiber is described by a coupled time-dependent coefficient fourth-order nonlinear Schr?dinger system, which is discussed in this paper. For such a system, we work out the Lax pair, Darboux transformation, and corresponding vector semi-rational nonautonomous rogue wave solutions. When the group velocity dispersion(GVD) and fourth-order dispersion(FOD) coefficients are the constants, we exhibit the first-and second-order vector semirational rogue waves which are composed of the four-petalled rogue waves and eye-shaped breathers. Both the width of the rogue wave along the time axis and temporal separation between the adjacent peaks of the breather decrease with the GVD coefficient or FOD coefficient. With the GVD and FOD coefficients as the linear, cosine, and exponential functions, we respectively present the first-and second-order periodic vector semi-rational rogue waves, first-and second-order asymmetry vector semi-rational rogue waves, and interactions between the eye-shaped breathers and the composite rogue waves. 相似文献
6.
7.
We proposed and demonstrated a bidirectional SCM-WDM PON using a reflective filter and cyclic AWG where up/downlink data could be provided using a single optical source. In the proposed scheme, the signal for downstream was modulated by a single CW laser diode and remodulated in the optical network unit as an upstream, the proposed WDM-PON scheme can offer the SCM signal for broadcasting service. In this paper, 1 Gb/s signals both for up- and downstream were demonstrated in 10 km bidirectional optical fiber link. 相似文献
8.
Huei Pei Kuo Paul Rosenberg Robert Walmsley Sagi Mathai Lennie Kiyama Joseph Straznicky Moray Mclaren Michael Tan Shih-Yuan Wang 《Applied Physics A: Materials Science & Processing》2009,95(4):955-965
We describe two free-space optical links for multichannel optical interconnects. The targeted aggregate data rate is 240 Gb/s.
In one implementation we use a unique implementation of telecentric optics and achieved an optical link that is simple, robust,
and modular. We describe a simple, inexpensive telecentric lens that can accommodate all optical channels within a 1-mm-diameter
sweet zone. We also describe the performance of an optical link with a 4×4 array of VCSELs and matching detectors. The integrity
of the optical link is not significantly degraded with a>±2 mm translational misalignment between the VCSEL and detector arrays. With the telecentric optical link, we need only two
low-bandwidth, single-axis active servomechanisms to compensate for static tilt and possibly low-frequency thermally-driven
shift between the transmitter and receiver arrays. In the other implementaion we use two matching arrays of 1×12 optical fibers.
Data are coupled optically through an air gap of 2 mm by means of a pair of collimating microlens arrays that are aligned
to one another via precision mechanical subassemblies. We describe a simple, inexpensive, and robust mechanical coupling for
the optical link achieved by using miniature high-flux magnets. 相似文献
9.
The purpose of this study is to investigate the potential use of a beryllium oxide (BeO) ceramic as a radioluminescence (RL) and optically stimulated luminescence (OSL) probe material for fibre-coupled luminescence dosimetry. A portable dosimetry system, named RL/OSL BeO FOD was developed, consisting of a 1 mm diameter, 1 mm long BeO ceramic cylinder coupled to a silica/silica optical fibre. The reader measures the RL signal and also uses a 450 nm laser diode to stimulate the BeO ceramic. A second background optical fibre is used to remove the stem effect. The RL/OSL BeO FOD was characterised in a solid water phantom, using a 6 MV x-ray beam. The RL was found to be reproducible and have a linear response to doses ranging from 30 cGy–15 Gy and dose rates from 100 cGy/min – 600 cGy/min. The OSL response was linear to doses of 10 Gy, becoming supralinear at higher doses. Measured percentage depth curves using the RL/OSL BeO FOD agreed with those measured using an IC15 ion chamber to within 5%, beyond the build up region. It was also found that the RL from BeO ceramic is unaffected by the delivered dose to the probe and hence, it remains constant for a given dose-rate. The insensitivity of the RL to accumulated dose makes BeO ceramic potentially capable of accurate dose-rate measurements without any corrections for the accumulated dose. This study demonstrates the feasibility of BeO ceramic as a versatile fibre-coupled luminescence dosimeter probe. 相似文献
10.
Jianxin Ma 《Fiber and Integrated Optics》2014,33(3):163-172
AbstractA full-duplex link implementing alternative wired and wireless access for wavelength-division multiplexing passive optical network is proposed with the uniformed three-tone converged optical signal, which provides a wired or wireless downlink access signal alternatively and an uplink optical carrier. The uplink optical carrier reversed by the converged optical signal makes the hybrid optical node unit free from the optical source. The simulation results show that the full-duplex link with a 10-Gb/s 16-quadrature amplitude modulation (16-QAM) downstream and 5 Gb/s binary upstream can provide both wired access with a bit-error rate below 10?9 and radio-over-fiber-based wireless access with a bit-error rate below 10?7 over 40 km of fiber without an optical source and optical amplifier in the hybrid optical node unit. 相似文献
11.
基于-OTDR和POTDR结合的分布式光纤微扰传感系统 总被引:1,自引:0,他引:1
提出了一种-OTDR和POTDR相结合的分布式光纤微扰传感系统.该系统将窄线宽DFB激光器作为传感光源同时应用到-OTDR和POTDR中,在不增加成本的前提下使两种系统合为一体,可同时检测传输光脉冲的相位和偏振态的变化,并使它们并行运行以提高传感系统对微扰远程定位检测的准确度,从而大幅减小误判率和漏报率.同时采用小波分析的方法来降低传感信号的噪音以进行后续的处理.实验结果表明,传感系统在14 km处获得具有较高信噪比的扰动信号,同时系统的空间分辨率也达到了50 m. 相似文献
12.
By the use of an auxiliary equation, we find bright and dark optical soliton and other soliton solutions for the higher-order nonlinear Schr(o)dinger equation (NLSE) with fourth-order dispersion (FOD), cubic-quintic terms, self-steepening, and nonlinear dispersive terms. Moreover, we give the formation condition of the bright and dark solitons for this higher-order NLSE. 相似文献
13.
A chip-scale optical link system is presented with a transmitter/receiver and optical wire link. The interchip link system consists of a metal optical bench, a printed circuit board module, a driver/receiver integrated circuit, a vertical cavity surface-emitting laser/photodiode array, and an optical wire link composed of plastic optical fibers (POFs). We have developed a downsized POF and an optical wiring method that allows on-site installation with a simple annealing as optical wiring technologies for achieving high-density optical interchip interconnection within such devices. Successful data transfer measurements are presented. 相似文献
14.
Francesco Matera Luca Rea Matteo Venezia Lorenzo Capanna Giuseppe Del Prete 《Fiber and Integrated Optics》2007,26(2):123-134
In this article we describe an experimental investigation of IP network restoration based on wavelength recovery. We propose a procedure for metro and wide area gigabit Ethernet networks that allows us to route the wavelength in case of link failure to another existing link by exploiting wavelength division multiplexing in the fiber. Such a procedure is obtained by means of an optical switch that is managed by a loss-of-light signal that is generated by a router in case of link failure. Such a method has been tested in an IP network consisting of three core routers with optical gigabit Ethernet interfaces connected by means of 50-km-long single-mode fibers between Rome and Pomezia. Compared with other conventional restoration techniques, such as OSPF and MPLS, our method -in very fast (20 ms) and is compatible with real-time TV services and low-cost chips. 相似文献
15.
Controlling the carrier-envelope phase of ultrashort light pulses with optical parametric amplifiers
The phase link between signal, idler, and pump waves in a parametric interaction allows generation of an idler pulse with a phase independent of that of the input pulse. We suggest the use of a white-light seeded optical parametric amplifier as a self-stabilized source of few-cycle pulses, in which the phase of the electric field is exactly reproduced in each laser shot. 相似文献
16.
In an optical fiber link with polarization-dependent loss (PDL), we demonstrate that although the complex polarization mode dispersion vector cannot be fully obtained by the reflectometric measurement, the spectrally resolved differential group delay (DGD) and differential attenuation slope (DAS) can be explicitly determined by such measurements performed simultaneously in the optical frequency domain and the fiber length domain. In principle, this technique can be used to realize the spectrally resolved and spatially resolved measurement of DGD and DAS in an optical fiber link having PDL based on distributed Rayleigh backscattering. We report the experimental result based on the far-end Fresnel reflection to confirm the validity of the proposed method. 相似文献
17.
分数阶微分技术在机载高光谱数据估算土壤含水量中的应用 总被引:2,自引:0,他引:2
无人机高光谱遥感为精准农业和农业信息化监测提供崭新视角。高光谱传感器具有厘米级空间分辨率和精细的光谱分辨率,可获取高质量的高光谱数据。然而,高光谱数据通常伴随噪声和数据冗余,高光谱信息利用效率低,常规预处理难以满足精准估算的需求。因此,为解决上述现实问题,针对机载高光谱影像的数据挖掘必不可少。利用分数阶微分(FOD)技术逐像元处理机载高光谱数据(步长为0.1)。通过对比FOD技术与整数阶技术对高光谱数据的改善能力,从光谱层面探寻最佳FOD阶数。在梯度提升回归树(GBRT)算法下构建土壤含水量(SMC)估算模型,最终在最佳模型下评估SMC的空间分布。结果表明:FOD技术提高光谱与SMC的相关系数(rmax=0.768),与原始光谱、一阶微分和二阶微分处理后的光谱同SMC相关系数相比,分别提升0.168,0.157和0.158。FOD技术提升模型估算精度的主因是突出有效光谱信息的作用,特别是与水分胁迫密切敏感的叶绿素、植物结构和水分响应波段(430,460,640,660和970nm)。即使FOD技术取得理想的结果,不同阶数的效果仍有差异。高阶FOD对影像增加了一定噪... 相似文献
18.
Jianxin Ma Ruijiao Zhang Junjie Zhang Xiangjun Xin 《Fiber and Integrated Optics》2013,32(5-6):217-229
AbstractA novel full duplex fiber wireless link providing alternative wired and 60-GHz wireless access is proposed based on a polarization orthogonal dual-tone optical millimeter-wave signal. In a hybrid optical network unit, the downlink optical signal can be decomposed as a single-sideband optical millimeter-wave signal (baseband optical signal) for wireless (wired) access by a polarization controller and polarization beam splitter. The uplink optical carrier abstracted from the downlink optical signal makes the hybrid optical network unit free from the optical source. The simulation results show that both downlinks and uplinks for either wired or wireless access can maintain quite good performance over 60 km of fiber. 相似文献
19.
20.
G. Ning S. Aditya P. Shum L. Cheng H. Dong 《Applied physics. B, Lasers and optics》2008,90(1):137-140
We propose novel photonic microwave multi-tap filters using a section of Hi-Bi fiber in a round-trip configuration, together
with their application in a 20 km single mode fiber (SMF) radio-over-fiber (RoF) link. We demonstrate for the first time that
the effect of chromatic dispersion in these multi-tap filters can be reduced in an RoF link when a linearly chirped fiber
Bragg grating (FBG) is adopted. This result can be used to combat radio frequency power fading in an RoF link. The configurations
are free from optical coherent interference and phase noise. Measured results show 3-tap filters with notch rejections greater
than 35 dB and suppression of the level of secondary sidelobes by adjusting a polarization controller.
PACS 42.81.-I; 42.81.Gs; 07.50.Qx 相似文献