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1.
光纤傅里叶变换光谱分析装置 总被引:10,自引:1,他引:9
报道了一种新的光谱测量方法-基于单模光纤Mach-Zehnder干涉仪(FMZI)结构的傅里叶变换光谱分析法。在传统傅里叶变换光谱仪( FTS ) 中,用光纤代替传统光路;用光纤耦合器取代传统分束器;用压电光程调制器取代传统移动镜;从而构建了光纤傅里叶变换光谱仪(FFTS)。利用该FFTS测量了LD在阈值以下的发射光谱并与光栅光谱仪测量结果进行了比较,结果表明测量结果是相互吻合的。初步的实验中由于光程调制有限,光谱分辨率为~7 cm-1,改造光程调制器可进一步提高光谱分辨率,证明了FFTS用于分析光谱的可行性。 相似文献
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High-speed free-space optical communication systems have recently used fiber-optical components. The coupling efficiency with which the received laser beam can be coupled into a single-mode fiber is noticeably limited by atmospheric turbulence due to the degradation of its spatial coherence. Fortunately, adaptive optics (AO) can alleviate this limitation by partially correcting the turbulence-distorted wavefront. The coupling efficiency improvement provided by Zernike modal AO correction is numerically evaluated. It is found that the first 3-20 corrected polynomials can considerably improve the fiber-coupling efficiency. The improvement brought by AO is compared with that brought by a coherent fiber array. Finally, a hybrid technique that integrates AO and a coherent fiber array is proposed. Results show that the hybrid technique outperforms each of the two above-mentioned techniques. 相似文献
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Tolerance on tilt error for coherent combining of fiber lasers 总被引:1,自引:0,他引:1
Limited by the precision of optical machining and assembling, the optical axes of lasers in an array cannot be strictly parallel to each other, which will result in the beam quality degradation of the combined beam. The tolerance on tilt error for coherent combining of fiber lasers is studied in detail. The complex amplitude distribution in the far field for the Gaussian beam with tilt angle is obtained by a novel coordinate transform method. Effect of tilt error on coherent combining is modelled analytically. Beam propagation factor is used to evaluate the effect of coherent combining. Numerical results show that for ring-distributed fiber laser array with central wavelength A and geometry size D, if the root-mean-square (RMS) value of the tilt error is smaller than 0.72A/D, the energy encircled in the diffraction-limited bucket can be ensured to be more than 50% of the value when there is no tilt error. The results are helpful to the designing and manufacturing of fiber array for coherent combining. 相似文献
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By virtue of the new technique of performing integration over Dirac’s ket–bra operators, we explore quantum optical version of classical optical transformations such as optical Fresnel transform, Hankel transform, fractional Fourier transform, Wigner transform, wavelet transform and Fresnel–Hadmard combinatorial transform etc. In this way one may gain benefit for developing classical optics theory from the research in quantum optics, or vice-versa. We cannot only find some new quantum mechanical unitary operators which correspond to the known optical transformations, deriving a new theorem for calculating quantum tomogram of density operators, but also can reveal some new classical optical transformations. For examples, we find the generalized Fresnel operator (GFO) to correspond to the generalized Fresnel transform (GFT) in classical optics. We derive GFO’s normal product form and its canonical coherent state representation and find that GFO is the loyal representation of symplectic group multiplication rule. We show that GFT is just the transformation matrix element of GFO in the coordinate representation such that two successive GFTs is still a GFT. The ABCD rule of the Gaussian beam propagation is directly demonstrated in the context of quantum optics. Especially, the introduction of quantum mechanical entangled state representations opens up a new area in finding new classical optical transformations. The complex wavelet transform and the condition of mother wavelet are studied in the context of quantum optics too. Throughout our discussions, the coherent state, the entangled state representation of the two-mode squeezing operators and the technique of integration within an ordered product (IWOP) of operators are fully used. All these have confirmed Dirac’s assertion: “...for a quantum dynamic system that has a classical analogue, unitary transformation in the quantum theory is the analogue of contact transformation in the classical theory”. 相似文献
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光纤相控阵在激光合束、激光雷达等领域具有应用前景.光纤阵列配置方式不同于微波相控阵,光纤天线间距大于波长时存在周期旁瓣问题,影响主瓣能量分布.本文从物理模型出发,建立了基于同心圆环形点阵集合的光学相控阵天线布阵理论模型,提出了利用解析延拓的傅里叶变换方法实现干涉场强度的快速合成理论,讨论了在离散采样时数值仿真需关注的采样带宽和采样数目问题,解决了快速实现多光束干涉场数值仿真的问题.对比研究了两种优化光学相控阵天线配置的优化算法:遗传算法和粒子群算法,分别实现了不同种群数量遗传算法和粒子群算法迭代优化,分析了二者在优化过程中的收敛速度和优化效果,得到了峰值旁瓣比PSR=0.270的配置阵列.所提出的方法有望用于实际的光学相控阵天线配置中,指导天线主瓣能量最大化的优化设计;研究模型对不可微分目标函数优化问题的研究有一定参考价值. 相似文献
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We propose a new method for phase retrieval and coherent diffraction imaging by a specially designed pinhole sampling array (PSA) based on a liquid crystal spatial light modulation. We demonstrate that the phase and the amplitude of the wave front passing through a pinhole sampling array plate can be directly extracted from the inverse Fourier transform of the far-field diffraction intensity pattern. Scanning the whole surface of the wave front by such a series of the PSA plates, we can assemble the extracted complex amplitude to a two-dimensional discrete distribution of the sampled wave front covering the entire PSA plate plane in the scanning consequence. We called it linear scanning pinhole sampling array (LSPSA). Thus the wave front can be reconstructed which avoids any iterative algorithms. Furthermore, it provides a feasible approach for lensless coherent diffraction imaging in real-time. 相似文献
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The very close positioning tolerances of the Fourier transform lens (FTL) in a coherent optical correlator with respect to the filter, can be a handicap for its use in an industrial environment. Replacing the single FTL by a lens array, this distance can be reduced by an order of magnitude, leading to constructions which are less sensitive to mechanical vibration. To each array-lens, a corresponding object field is related. This permits a splitting up of information, which facilitates the interpretation of variations between the objects under test. The optical properties of the correlation system and their influence on the autocorrelation function and cross talk are discussed. 相似文献
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LIU Yange LIU Wei ZHANG Yimo ZHOU Ge 《Chinese Journal of Lasers》2000,9(3):206-212
1 Introduction Withtherapiddevelopmentoftheopticalfibercommunicationtechnologiesinrecentdecades,opticalfibershavebeenwidelyandsuccessfullyusedintelephonecommunication,datatransfer,closedcircuittelevision,industrialcontrolandsupervision,andsensor,etc.[1].O… 相似文献
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A hybrid opto-electronic correlator for detecting defects in optical fibers is proposed. After the light from a He-Ne laser being expanded and filtered it is not collimated but directly passes a Fourier transform lens and illuminates a reference fiber and a test fiber at the same input plane. The Fourier transform spectrum of the two fibers is therefore obtained at the rear focal plane of the lens, where it is sampled via a CCD array connected with a computer through a frame grabber. The computer performs filter, inverse Fourier transform and setting threshold operation on classification. The system is an equivalent of joint transform correlator with a Fourier lens of long focal length. The experiment results for optical fibers having incoordinate defects are presented. The results indicate that the system can be used for fiber defect detection, and has the advantages of high identification, compact configuration, easy adjustment and flexible manipulation. 相似文献
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Y Yan Y Yue H Huang JY Yang MR Chitgarha N Ahmed M Tur SJ Dolinar AE Willner 《Optics letters》2012,37(17):3645-3647
We propose an approach to efficiently generate and multiplex optical orbital angular momentum (OAM) modes in a fiber with a ring refractive index profile by using multiple coherent inputs from a Gaussian mode. By controlling the phase relationship of the multiple inputs, one can selectively generate OAM modes of different states l. By controlling both the amplitude and phase of the multiple inputs, multiple OAM modes can be generated simultaneously without additional loss coming from multiplexing. We show, by simulation, the generation of OAM modes (OAM state |l|<3) with mode purity greater than 99%. The power loss of generating and multiplexing seven modes is about 35%. A transmitter for an OAM-based mode-division multiplexing system is proposed based on the discrete Fourier transform between the data carried by the multiple inputs and the data carried by the OAM modes. The experimental implementation of the proposed approach could be achieved by integrating ring fiber, multicore fiber, and photonic integrated circuit technology. 相似文献
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Random fractional Fourier transform 总被引:4,自引:0,他引:4
We propose a novel random fractional Fourier transform by randomizing the transform kernel function of the conventional fractional Fourier transform. The random fractional Fourier transform inherits the excellent mathematical properties from the fractional Fourier transform and can be easily implemented in optics. As a primary application the random fractional Fourier transform can be directly used in optical image encryption and decryption. The double phase encoding image encryption schemes can thus be modeled with cascaded random fractional Fourier transformers. 相似文献
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Biophotonics and nonlinear fiber optics have traditionally been two independent fields. Since the discovery of fiber‐based supercontinuum generation in 1999, biophotonics applications employing incoherent light have experienced a large impact from nonlinear fiber optics, primarily because of the access to a wide range of wavelengths and a uniform spatial profile afforded by fiber supercontinuum. However, biophotonics applications employing coherent light have not benefited from the most well‐known techniques of supercontinuum generation for reasons such as poor coherence (or high noise), insufficient controllability, and inadequate portability. Fortunately, a few key techniques involving nonlinear fiber optics and femtosecond laser development have emerged to overcome these critical limitations. Despite their relative independence, these techniques are the focus of this review, because they can be integrated into a low‐cost portable biophotonics source platform. This platform can be shared across many different areas of research in biophotonics, enabling new applications such as point‐of‐care coherent optical biomedical imaging. 相似文献
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Omega network plays an important role in all optical communication and optical interconnection networks. In this paper, a novel technology, which binary optics element (micro-blazed grating array) can realize perfect shuffle transform including inverse perfect shuffle and left perfect shuffle, is proposed. Moreover, by a cascade of inverse perfect shuffle and left perfect shuffle, a multistage rearrangeable nonblocking omega network can be constructed. Simultaneously, the bipartition graph algorithm (BGA) is adopted to ascertain the state of node switch in each node stage (straight or crossover connection). At last, a module of the rearrangeable nonblocking omega network which is integrated with polarizing beam-splitter, half-wave plate, micro-blazed grating array, is presented. It can accomplish the functions of 8-channel signal beams’ sorting and switching without routing conflict and blocking, and has advantages of being compact in structure, easy to integrate, efficient in performance etc. Finally, both the theoretical analysis and the experimental result show that this module proposed here may be helpful in free-space optical interconnection network and optical information processing. 相似文献
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F. Bayrakçeken 《Applied physics. B, Lasers and optics》2011,105(3):573-574
Ultraviolet light induced high resolution optical absorption spectra and resonance coherent fluorescence of spectroscopically
pure fused silica have been studied, due to their potential applications in optoelectronics and laser flash spectroscopy for
laboratory use, for optical fibers and for power optics for lasers. Ultraviolet discrete absorption spectra and resonance
coherent fluorescence were recorded photographically between 200 and 260 nm. Resonance discrete and coherent fluorescence
(i.e. lasing effect) were observed in the 250–255 nm band at room temperature by high photon flux excitation spectroscopy. 相似文献
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基于傅里叶光学二次滤波技术,本文提出了一种新的光学图像相减方法,即全息滤波光学图像相减法,该方法需用图像的逆转和匹配两种滤波器和一个8f光学系统,实验表明,作为一种新的图像相减方法,避免了以往实时法对光程的精细控制,因而降低了对辅助设备和环境的要求. 相似文献
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ZHAO Liping WU Minxian MAO Wenwei JIN Guofan YAN Yingbai 《Chinese Journal of Lasers》1998,7(5):413-418
1IntroductionWiththedevelopmentoftheintegratedopticsandfabricationtechnologyofsemiconductor,opticalFouriertransform(OFT)isbec... 相似文献