共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
This paper proposes an all-optical label processing scheme that uses the multiple optical orthogonal codes sequences (MOOCS)-based optical label for optical packet switching (OPS) (MOOCS-OPS) networks. In this scheme, each MOOCS is a permutation or combination of the multiple optical orthogonal codes (MOOC) selected from the multiple-groups optical orthogonal codes (MGOOC). Following a comparison of different optical label processing (OLP) schemes, the principles of MOOCS-OPS network are given and analyzed. Firstly, theoretical analyses are used to prove that MOOCS is able to greatly enlarge the number of available optical labels when compared to the previous single optical orthogonal code (SOOC) for OPS (SOOC-OPS) network. Then, the key units of the MOOCS-based optical label packets, including optical packet generation, optical label erasing, optical label extraction and optical label rewriting etc., are given and studied. These results are used to verify that the proposed MOOCS-OPS scheme is feasible. 相似文献
4.
在光学没计中,一般认为在同一光波面上,光束具有相同的振幅和偏振状态。事实上,光束经过许多光学元件后,偏振状态会发生变化,特别是入射角和光程的不同,会导致出射光波面上偏振分布不再均匀,形成偏振象差。本文主要就轴上物点发出的光束经过界面反射后的偏振象差方面进行了分析。 相似文献
5.
目前用于光学设计的计算机辅助设计有许多种,但它们在像差特性参数的形式和表示方法上不尽相同,特别是国内外软件的这种差别更为明显,例如:ZEMAX将球差表示为“Longitudinal aberration”(纵向像差),其表示形式也与国内软件不同。另外,有些像差参数需要转换。采用美国焦点软件公司开发的光学设计软件ZEMAX和国内北京理工大学编写的DOS版CAOD对同一双胶合透镜进行光路计算,同时对其轴上球差、彗差、场曲和畸变等主要几何像差在2个软件之间的差别进行比较,以建立国内软件与国外软件在进行光学镜头设计时的光学像差特性参数的转换关系,并为光学设计者提供设计一种镜头或光学系统时使用不同的软件进行数据核查和复算的方法。 相似文献
6.
In this study, a competent numerical strategy to compute the dispersion of optical waveguides is presented and propagation of electromagnetic waves in a coaxial optical waveguide with DB boundary conditions is instigated. For this intend, cylindrical coordinates are here being used to derive the DB boundary conditions and to obtain field components for the modes. The propagation constant for the waveguide to be studied is determined by solving the Bessel and the modified Bessel functions. The cutoff frequencies for various lower order modes have been calculated and their dispersion characteristics are plotted correspondingly. The behavior of the coaxial optical waveguide under DB boundary conditions is shown to be significantly different from that of coaxial optical waveguide and conventional optical waveguide under traditional or tangential boundary conditions. Finally, the effect of waveguide dimensions on the mode cutoff frequencies and fabrication issues are also addressed. 相似文献
7.
This recent study shed demonstration on how the structural parameters changes due exposure to UV radiation and different wavelengths. So this article throws light on the changes of the optical properties and some structural properties due exposure to UV radiation and different wavelengths on irregular rayon acetate fibers. Pluta polarizing interference microscope is used to study the changes for refractive indices and birefringence with different exposure times at three different intensities on irregular rayon acetate fibers. As the principal optical parameters determined, these give an indication of the isotropic refractive index, stress optical coefficient, stress due to UV radiation, optical configuration parameter, segment anisotropy, the number of molecules per unit volume and polarizability of a monomer unit can be obtained. Also by using different wavelengths are given the spectral dispersions, Cauchy's dispersion constants, the resonant wavelength, the oscillation energy, the dispersion energy, the dielectric constant and the dielectric susceptibility for rayon acetate fibers with different wavelengths at room temperatures. Illustrations are given using graphs and microinterferograms. 相似文献
8.
Systematical study of the trapping forces of optical tweezers formed by different types of optical ring beams 总被引:2,自引:0,他引:2 下载免费PDF全文
The technique of optical tweezers has been improved a lot since its
invention, which extends the application fields of optical tweezers. Besides
the conventionally used Gaussian beams, different types of ring beams have also been
used to form optical tweezers for different purposes. The two typical
kinds of ring beams used in optical tweezers are the hollow Gaussian beam and
Laguerre--Gaussian (LG) beam. Both theoretical computation and experiments
have shown that the axial trapping force is improved for the ring beams
compared with the Gaussian beam, and hence the trapping stability is
improved, although the transverse trapping forces of ring beams are smaller
than that of Gaussian beam. However, no systematic study on the trapping
forces of ring beam has ever been discussed. In this article, we will investigate
the axial and transverse trapping forces of different types of ring beams
with different parameters systematically, by numerical computation in which
the ray optics model is adopted. The spherical aberration caused by the
refractive index mismatch between oil and water is also considered in the
article. The trapping forces for different objectives that obey the sine
condition and tangent condition are also compared with each other.
The result of systematical calculation will be useful for the applications
of optical tweezers formed by different types of ring beams. 相似文献
9.
Nonlinear photonic crystals made from polystyrene materials that have Kerr nonlinearity can exhibit ultrafast optical switching when the samples are pumped by ultrashort optical pulses with high intensity due to the change of the refractive index of polystyrene and subsequent shift of the band gap edge or defect state resonant frequency. Polystyrene has a large Kerr nonlinear susceptibility and almost instantaneous response to pump light, making it suitable for the realization of ultrafast optical switching with a response time as short as a few femtoseconds. In this paper, we review our experimental progress on the continual improvement of all-optical switching speed in two-dimensional and three-dimensional polystyrene nonlinear photonic crystals in the past years. Several relevant issues are discussed and analyzed, including different mechanisms for all-optical switching, preparation of nonlinear photonic crystal samples by means of microfabrication and self-assembly techniques, characterization of optical switching performance by means of femtosecond pump-probe technique, and different ways to lower the pump power of optical switching to facilitate practical applications in optical information processing. Finally, a brief summary and a perspective of future work are provided. 相似文献
10.
本文通过分析一定功率的脉冲光射入光纤中的布里渊散射规律,介绍了分布式光纤测量测量轴向应力的基本原理。制作实验装置,测量单独的应变模型,分析散射回来的波形图,初步了解应力在光纤布里渊散射波谱上的图像特征。将应力作用于光纤的不同位置,对比它们与无应力作用诗所得到的散射波形之间的图像差异,研究其对光脉冲在光纤传输过程中的影响规律。结果表明,应力的作用大小,作用位置的不同都会对脉冲光的传播造成影响,主要在于影响布里渊散射的斯托克斯光和反斯托克斯光。本次研究所得可以为分布式光纤测量提供参考,为分布式光纤在测量微型形变的应用中有一定的促进作用。本次研究的创新点在于使用滑轮的方法,解决同等应力在分布光纤的不同位置作用效果。 相似文献
11.
Ye Liu Fei Qin Fei Zhou Qing-bo Meng Dao-zhong Zhang Zhi-yuan Li 《Frontiers of Physics in China》2010,5(3):220-244
Nonlinear photonic crystals made from polystyrene materials that have Kerr nonlinearity can exhibit ultrafast optical switching
when the samples are pumped by ultrashort optical pulses with high intensity due to the change of the refractive index of
polystyrene and subsequent shift of the band gap edge or defect state resonant frequency. Polystyrene has a large Kerr nonlinear
susceptibility and almost instantaneous response to pump light, making it suitable for the realization of ultrafast optical
switching with a response time as short as a few femtoseconds. In this paper, we review our experimental progress on the continual
improvement of all-optical switching speed in two-dimensional and three-dimensional polystyrene nonlinear photonic crystals
in the past years. Several relevant issues are discussed and analyzed, including different mechanisms for all-optical switching,
preparation of nonlinear photonic crystal samples by means of microfabrication and self-assembly techniques, characterization
of optical switching performance by means of femtosecond pump-probe technique, and different ways to lower the pump power
of optical switching to facilitate practical applications in optical information processing. Finally, a brief summary and
a perspective of future work are provided. 相似文献
12.
The outstanding phase‐noise performance of optical frequency combs has led to a revolution in optical synthesis and metrology, covering a myriad of applications, from molecular spectroscopy to laser ranging and optical communications. However, the ideal characteristics of an optical frequency comb are application dependent. In this review, the different techniques for the generation and processing of high‐repetition‐rate (>10 GHz) optical frequency combs with technologies compatible with optical communication equipment are covered. Particular emphasis is put on the benefits and prospects of this technology in the general field of radio‐frequency photonics, including applications in high‐performance microwave photonic filtering, ultra‐broadband coherent communications, and radio‐frequency arbitrary waveform generation. 相似文献
13.
Monte Carlo model of optical coherence tomography is developed for simulation of photon transport in half infinite homogenous media. The procedure is accelerated by scaling the baseline data from standard Monte Carlo calculation in turbid media with arbitrary optical parameters. Gaussian beam is modeled by hyperboloid of one sheet for actual condition to obtain distribution of photons on sample surface. Depth dependence coherent signal and photons distribution are calculated in this way, which is important to reconstruction of optical parameters by inverse Monte Carlo. Numerical results have verified this method in turbid medium of different optical parameters with acceptable relative errors. 相似文献
14.
It is difficult to exactly control the film thickness of optical disk multilayer in the actual coating process. The thickness error becomes a main factor affecting the optical characters of the film system. The thickness error′s sensitivity factor of dielectric optical multilayer is derived from the optical matrix in this paper. The effect of the thickness error on the reflectivity or reflectivity contrast of the optical disk multilayer is analyzed with a numerical calculation. The sensitivities to thickness error for different layers or in different film-thickness ranges are compared and discussed. A sketchy method defining allowable thickness error is given. Some experimental results verify the applicability of our theoretical analysis. 相似文献
15.
Jianbai Li Anqing Zhao Senquan Wei Baolin Yu Xuegang Cheng Xiong Wan Xiaolin Zhang 《Optical Review》1994,1(2):254-255
Some formulae on correlative match of both optical aperture and wave aberration to determine image quality are derived in this paper. The optimizing match zone on optical aperture and wave aberration were found both theoretically and experimentally. The results are importantly different from traditional criteria for image quality. 相似文献
16.
WANG Yang GU Donghong GAN Fuxi 《Chinese Journal of Lasers》2001,10(3):206-210
1 Introduction Recentlyopticaldisksabletostorealargequantityofinformationhavebeenusedascompactdisk (CD ) ,digitalversatiledisk(DVD) ,andtheirrecordableorrewritabletypes(suchasCD R ,CD RW ,DVD R ,andDVD RAM ) [1 ] .Anopticaldiskisakindofmultilayersystemdepositedona… 相似文献
17.
18.
According to the present passive optical network (PON) standard, the fiber transmission lengths are from 500 m to 20 km between the optical line terminal (OLT) and different optical network units (ONUs). It will result in difference power losses (ΔPloss) from 4 to 5 dB. Hence, we propose to adjust adaptively the output optical power of the upstream laser diode (LD) depending on the different fiber lengths. With the different fiber transmission lengths, we can properly adjust the bias current and modulation index of upstream LD for energy-saving. We characterize and analyze experimentally the relationship of output optical power and modulation amplitude Vamp under different fiber transmissions in PON access. Moreover, due to the adaptive power control of upstream signal, the optical upstream equalization also can be retrieved with power variation of 1.1 dB in this experiment. 相似文献
19.
20.
理论模拟了激光束通过磁流体样品后产生的远场光斑图样,提出了一种阈值可调光学限幅器的实现方案.计算了不同光阑孔径半径和不同光阑样品距离情况下,系统的出射光功率与入射光功率的关系.得出了系统的光学限幅阈值随光阑孔径半径的增大以及光阑样品距离的减小而向高功率方向转移的结论,且限幅阈值与光阑孔径半径之间呈线性关系.定义了描述磁流体样品特征的参量f,发现了系统的光学限幅阈值随f的绝对值增加而减小.本文的结论能为实际的磁流体基可调谐光学限幅器的设计与制作提供有益的参考. 相似文献