Structured light fields arc a kind of special light fields that have tailored lightwave spatial structure. The generalized structured light fields arc these kinds of fields including spatially variant amplitude, phase...
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Structured light fields arc a kind of special light fields that have tailored lightwave spatial structure. The generalized structured light fields arc these kinds of fields including spatially variant amplitude, phase and polarization distribution as well as space array. Structured light fields have seen wide applications in optical manipulation, microscopy, imaging, metrology, sensing, nonlinear optics, astronomy, quantum science and optical communications owing to their distinct advantages. Structured light communication techniques include multiplexing communications and coding/decoding communications. In this review article, the recent progress of structured light coding/decoding communications is retrospected. Various generation methods of structured light fields and structured light coding/decoding communications with different spatial modes (orbital angular momentum mode, non -diffraction Bessel mode, linearly polarized mode, vector mode, space array), different coding methods (direct mode coding, high-speed mapping), and different scenarios (photonic chip, free space, fiber) arc comprehensively reviewed. Future trend and perspective arc also discussed. Structured light coding/decoding communications exploit the space domain dimensional resources of light fields, which provide a potential solution to address the new capacity crunch of optical communications and enable sustainable expansion of optical communications.
We experimentally demonstrate visible-light coding/decoding utilizing hexadecimal vector beam array for parallel communication link. The hexadecimal base mode is investigated and 128-my is also available. We present v...
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ISBN:
(纸本)9781538632734
We experimentally demonstrate visible-light coding/decoding utilizing hexadecimal vector beam array for parallel communication link. The hexadecimal base mode is investigated and 128-my is also available. We present vector beam array carrying 4x6/6x8/12x16 hexadecimal numbers and error-free data stream transmission performance is also demonstrated.
We propose a simple approach to manipulating the constellation of a multilevel modulation signal in the optical domain. By exploiting degenerate four-wave mixing (FWM) in highly nonlinear fibers and adopting 16-ary qu...
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We propose a simple approach to manipulating the constellation of a multilevel modulation signal in the optical domain. By exploiting degenerate four-wave mixing (FWM) in highly nonlinear fibers and adopting 16-ary quadrature amplitude modulation (16-QAM) signal, we demonstrate 10-Gbaud/s optical variable symbol-wise hexadecimal coding/decoding assisted by a continuous-wave (CW) pump or a phase-modulated pump. The former takes the coding through the phase conjugation of degenerate FWM, and the latter offers enhanced coding via the combined contributions from the phase modulation of the pump and the phase-conjugated FWM. The penalty of optical signal-to-noise ratio for coding/decoding is measured to be <1.1 dB with a CW pump and <1.2 dB with a (0, pi/4) phase-modulated pump at a bit-error rate of 2e-3 (enhanced forward error correction threshold). The dependence of coding/decoding performance on the phase modulation depth of the pump and the signal/pump misalignment is also investigated. Moreover, considering that a hexadecimal number denotes four binary numbers, we develop the symbol-wise hexadecimal coding/decoding to general binary coding/decoding, i.e., 10-Gbaud/s symbol-wise hexadecimal coding/decoding is accompanied by 40-Gbit/s binary coding/decoding.
This paper presents a new approach for the protection of travel documents. We propose a digital watermarking technique which requires for the verification process a low scanning resolution of at least 72 DPI. The appr...
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ISBN:
(纸本)0819452130
This paper presents a new approach for the protection of travel documents. We propose a digital watermarking technique which requires for the verification process a low scanning resolution of at least 72 DPI. The approach is based on the wavelet decomposition and supports three key aspects: Message encoding is accomplished by iterative error correction codes satisfying a nearly optimal channel capacity. This encoding is based on specific modulation that requires for the implementation a significant lower complexity as the often applied M-array modulation. The watermark embedding is applied in the wavelet domain based on stochastic driven perceptional criteria for a good quality and invisibility. The watermarking process is considered as a communication process with side information. The approach utilizes two different watermarks, one for the channel state information estimation and one for the informative watermark which carries as a payload the hidden information.
In this paper, the performance of suboptimal convolutional decoding over fading channels is explored. The suboptimal decoding algorithm used is the bidirectional algorithm. By estimating a "decoder weight spectru...
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In this paper, the performance of suboptimal convolutional decoding over fading channels is explored. The suboptimal decoding algorithm used is the bidirectional algorithm. By estimating a "decoder weight spectrum" for the decoder, an "equivalent free distance" may be observed. Furthermore, by using this "decoder weight spectrum," useful estimations of the error probabilities are obtained and compared to computer-simulation results in the case of very slow and very fast fading. The resultant curves are shown to be very tightly related. Computer-simulation results are also shown for various signal-to-noise ratios, normalized Doppler spreads, and frame length on three typical fading channels: the Rayleigh fading channel with exponential and Bessel autocorrelation functions and the Rician fading channel with exponential autocorrelation function, We show that considerable gains (up to 4 dB) can be obtained with respect to a similar-complexity Viterbi decoder at a frame error probability P-e = 10(-3) and a slightly smaller gain (up to 1.8 dB) at a bit error probability P-b = 10(-5).
Structured (or model-based or analysis-synthesis) video refers to the representation of moving scenes in terms of component parts which are assembled according to scripting information to produce images for viewing. T...
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Structured (or model-based or analysis-synthesis) video refers to the representation of moving scenes in terms of component parts which are assembled according to scripting information to produce images for viewing. This sort of representation has advantages for both compression and interactivity. We describe a software implementation on a data-flow computer system which renders and composites two- and three-dimensional moving objects for display of compressed real and synthetic scenes.< >
PLLs (phase locked loops) are expected to be desirable components for clock extraction in high speed digital communication systems, typically in optical systems, because of the low cost, compactness, suitability to in...
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PLLs (phase locked loops) are expected to be desirable components for clock extraction in high speed digital communication systems, typically in optical systems, because of the low cost, compactness, suitability to integration, and ease of treatment. The PLL for clock extraction requires a fast pull-in and small output jitter characteristics. In this paper, we describe a total PLL system, in which a further improvement of the pull-in time is realized and a pseudo lock (i.e. harmonic lock), which has been a serious problem in the past, can be avoided automatically. We have constructed the PLL system using a monolithic PU-IC for the PLL core part and 1.2 micron design rule PLAs for most of the remaining part of the system, and measured total performances of the system.
The area and power consumption of oversampled data converters are governed largely by the associated digital decimation and interpolation filters. This paper presents an area- and power-efficient programmable digital ...
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The area and power consumption of oversampled data converters are governed largely by the associated digital decimation and interpolation filters. This paper presents an area- and power-efficient programmable digital filter for decimation and interpolation in digital-audio applications. Several architectural and implementation features reduce the complexity of the filter and allow its implementation in a die area of only 3670 mils/sup 2/ (2.37 mm/sup 2/). The filter is first described in the context of decimation for an oversampled A/D converter employing a second-order sigma-delta modulator. Extensions of the filter to accommodate other modulators, as well as to perform interpolation for oversampled D/A conversion, are then discussed.
A JPEG compliant Huffman decoder circuit has been developed. The circuit executes at 27 MHz in order to maintain image data transfer at CCIR 601 video rates. The circuit detects and decodes variable length Huffman cod...
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A JPEG compliant Huffman decoder circuit has been developed. The circuit executes at 27 MHz in order to maintain image data transfer at CCIR 601 video rates. The circuit detects and decodes variable length Huffman codes in a single clock cycle by searching among all Huffman codes in the current table. The circuit utilizes a CAM with mask bits to perform this rapid search. The architecture also utilizes a double barrel shifter to window the next portion of the input bit stream to be examined, which makes the critical path as short as possible. According to the simulation results, the delay of execution in a cycle is 18.1 ns. The total memory size is 15K bits.
A novel algorithm and subroutine is presented for encoding and decoding calendar dates. For encoding a numeric calendar date in the form day, month, year is converted into an integer variable in the range between 215-...
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A novel algorithm and subroutine is presented for encoding and decoding calendar dates. For encoding a numeric calendar date in the form day, month, year is converted into an integer variable in the range between 215-1 and -215. With decoding this integer variable is converted into numeric day, month and year. The algorithm performs very quickly and takes only 7 lines of FORTRAN code for encoding and decoding respectively.
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