| 1. |
- Almlöf, Jonas, et al.
(författare)
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A short and efficient error correcting code for polarization coded photonic qubits in a dissipative channel
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:1, s. 550-554
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Tidskriftsartikel (refereegranskat)abstract
- We propose a short and efficient non-degenerate quantum error correcting code that is adapted for qubits encoded on two orthogonal, single-photon states (e.g., horizontally and vertically polarized) subject to a dissipative channel. The proposed code draws its strength from the fact that it is adapted to the physical characteristics of the information-carrying basis states under the action of the channel. The code combines different energy manifolds and consists of only 3 spatio-temporal modes and on average 2 photons per code word.
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| 2. |
- Amer, Eynas, et al.
(författare)
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Stimulated laser induced fluorescence holography for imaging fluorescent species
- 2013
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 311, s. 124-128
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Tidskriftsartikel (refereegranskat)abstract
- In this paper pulsed digital holographic detection is coupled to the stimulated laser induced fluorescence (LIF) effect for imaging fluorescent species. A frequency tripled Q-switched Nd-YAG laser (wavelength 355 nm, pulse duration 12 ns) has been used to pump Coumarin 153 dye solved in ethanol. Simultaneously a frequency doubled pulse (532 nm) from the same laser is used to probe the solvent resulting in a gain through stimulated emission. The resulting gain of the probe beam is recorded using digital holography by blending it with a reference beam on the detector. Intensity maps were calculated from the recorded digital holograms and used to calculate the gain of the probe beam due to stimulated fluorescence emission which is coupled to the concentration of the dye. The results show that the amplification of the probe beam (532 nm) due to stimulated LIF emission is seen in the intensity maps. The gain is about 40% at a dye concentration of 0.32 g/L and decreases to be about 20% at a dye concentration of 0.04 g/L for a probe beam energy density of 0.1 mJ/cm2. Spectroscopic measurements have been carried out to confirm the holographic results. The results show that stimulated LIF holography is a promising technique for quantitative imaging of fluorescent species.
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| 3. |
- Banerjee, S., et al.
(författare)
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Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:9, s. 2278-2291
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Tidskriftsartikel (refereegranskat)abstract
- Optical chaos is a topic of current research characterized by high-dimensional nonlinearity which is attributed to the delay-induced dynamics, high bandwidth and easy modular implementation of optical feedback. In light of these facts, which add enough confusion and diffusion properties for secure communications, we explore the synchronization phenomena in spatiotemporal semiconductor laser systems. The novel system is used in a two-phase colored image encryption process. The high-dimensional chaotic attractor generated by the system produces a completely randomized chaotic time series, which is ideal in the secure encoding of messages. The scheme thus illustrated is a two-phase encryption method, which provides sufficiently high confusion and diffusion properties of chaotic cryptosystem employed with unique data sets of processed chaotic sequences. In this novel method of cryptography, the chaotic phase masks are represented as images using the chaotic sequences as the elements of the image. The scheme drastically permutes the positions of the picture elements. The next additional layer of security further alters the statistical information of the original image to a great extent along the three-color planes. The intermediate results during encryption demonstrate the infeasibility for an unauthorized user to decipher the cipher image. Exhaustive statistical tests conducted validate that the scheme is robust against noise and resistant to common attacks due to the double shield of encryption and the infinite dimensionality of the relevant system of partial differential equations.
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| 4. |
- Bhaduri, Basanta, et al.
(författare)
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Two wavelength simultaneous DSPI and DSP for 3D displacement field measurements
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:10-11, s. 2437-2440
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Tidskriftsartikel (refereegranskat)abstract
- A novel optical system is proposed that implements digital speckle pattern interferometry (DSPI) and digital speckle photography (DSP) simultaneously using two wavelength illumination of an object for simultaneous measurement of all three components of the displacement vector field. A collimated red light illuminates both the object and a reference surface in a DSPI configuration which is sensitive to out-of-plane displacement field while a blue light illuminates the object in a DSP configuration which is sensitive to in-plane displacement fields. A color 3-CCD camera records the red and blue lights individually through its red and blue channels, respectively. Two reference images and one image in the deformed state of the object are required for quantitative measurement. Experimental results are presented to validate the system.
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| 5. |
- Björk, Gunnar, et al.
(författare)
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Quantum degrees of polarization
- 2010
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:22, s. 4440-4447
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Tidskriftsartikel (refereegranskat)abstract
- We discuss different proposals for the degree of polarization of quantum fields. The simplest approach, namely making a direct analogy with the classical description via the Stokes operators, is known to produce unsatisfactory results. Still, we argue that these operators and their properties should be basic for any measure of polarization. We compare alternative quantum degrees and put forth that they order various states differently. This is to be expected, since, despite being rooted in the Stokes operators, each of these measures only captures certain characteristics. Therefore, it is likely that several quantum degrees of polarization will coexist, each one having its specific domain of usefulness.
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| 6. |
- Chamaillard, K., et al.
(författare)
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Coherency matrix description for statistical linear regression of Stokes parameters in rough small-particle scattering
- 2010
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:22, s. 4519-4524
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Tidskriftsartikel (refereegranskat)abstract
- A statistical analysis of the Stokes parameters in light scattering by randomly rough small particles shows a linear regression law between the squares of the first two components I-s and Q(s) of the Stokes vector. While the coefficients of this linear regression contain physical characteristics of the particles, they cannot be directly interpreted in terms of the degree of polarization of the scattered field. We propose an interpretation of this relationship between the Stokes parameters on the basis of the general coherence-density matrix formalism. The link between the statistical regression results and the polarization properties of the stochastic scattered components of the field is established through the coherency matrix elements.
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| 7. |
- Drummond, Miguel V., et al.
(författare)
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All-optical generation of 40 Gb/s single sideband signals using a fiber Bragg grating
- 2010
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:12, s. 2492-2495
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we demonstrate a reliable all-optical technique for performing optical double sideband (ODSB) to single sideband (OSSB) format conversion of a 40 Gb/s non-return-to-zero signal. It is based on the optimization of a detuned optical filter, which was implemented on a fiber Bragg grating (FBG) with a complex apodization profile. An OSSB signal with negligible distortion was obtained, as the FBG presented a nearly ideal frequency response. Higher tolerance to chromatic dispersion enabled by the OSSB signal in comparison to the ODSB signal was demonstrated on both simulation and experimental results. (C) 2010 Elsevier B.V. All rights reserved.
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| 8. |
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| 9. |
- Islam, A. B. M. Hamidul, et al.
(författare)
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Very low input voltage cascaded travelling wave electroabsorption modulator (CTWEAM) for more than 100 Gbps
- 2013
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 297, s. 43-47
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the large signal modeling and simulation of two segmented travelling wave electroabsorption modulators (TWEAM) as a cascaded TWEAM (CTWEAM) structure. It will be demonstrated that a mushroom shaped mesa structure with low series resistance (0.69 Omega-mm) will have 3 dB bandwidth more than sufficient for 100 Gbps operation. For a CTWEAM device with 990 lam active segment length, 1.1 V bias voltage and only 0.4 V peak-to-peak (Vp-p) modulating voltage has a bandwidth of 110 GHz, extinction ratio >4 dB and flat frequency response. This device would be an attractive candidate for short distance optical fiber communication as well as long distance telecommunication at 0.4 Vp-p and 1 Vp-p input RF signal, respectively.
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| 10. |
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| 11. |
- Lee, Hwang Woon, et al.
(författare)
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Evaluation of the third-order optical nonlinearity of Au:SiO2 nanocomposites in the off-resonant spectral region
- 2013
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 286, s. 347-352
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Tidskriftsartikel (refereegranskat)abstract
- The third-order nonlinear optical susceptibility (chi((3))) of Au:SiO2 nanocomposite films with different Au particle sizes was measured to be on the order of 10(-10) esu to 10(-9) esu in the off-resonant spectral region, and the particle size-dependent behavior of chi((3)) was observed. The results were found to deviate substantially from those of the conventional Maxwell-Garnet theory. By adapting the modified invariant imbedding method, which takes into account the effect of interparticle interactions on the nonlinear response, we successfully explain the enhanced third-order nonlinear susceptibility of metal-dielectric nanocomposites at off-resonant wavelengths.
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| 12. |
- Lindberg, J., et al.
(författare)
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Coherence and polarization properties of a three-dimensional, primary, quasi-homogeneous, and isotropic source and its far field
- 2010
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:22, s. 4452-4456
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Tidskriftsartikel (refereegranskat)abstract
- We study the spatial coherence properties of a three-dimensional, primary, quasi-homogeneous, and isotropic source and the far field that it generates. We assess the spectrum, degree of polarization, electromagnetic degree of coherence, and effective degree of coherence of the source and of the far field. We also demonstrate the formalism for a spherical Gaussian Schell-model current source. The polarization properties of light are fully accounted for in the analysis, and it is found that certain results pertaining to scalar coherence theory are reproduced also within the electromagnetic treatment.
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| 13. |
- Shen, Jian Qi
(författare)
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Dispersion-sensitive surface plasmon wave assisted by incoherent gain
- 2014
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 329, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- A three-level system with pumped electric-dipole allowed transition for incoherent-gain negative permittivity is suggested in order to realize dispersion-sensitive surface plasmon wave. The present surface wave modes occurring at an interface between an incoherent-gain negative-permittivity "plasmonic" medium (e.g., a semiconductor-quantum-dot material) and an ordinary dielectric can be amplified due to population transfer in the three-level system of the negative-permittivity medium. The issues of complex phase constant and the attenuation coefficients in the adjacent media are considered for addressing the problem of loss compensation of surface plasmon wave. The effect of incoherent-gain amplification exhibited by the dispersion-sensitive surface plasmon wave can be utilized for designing new quantum optical and photonic devices, e.g., photonic transistors and logic gates.
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| 14. |
- Song, Yi, et al.
(författare)
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Reducing crosstalk between nanowire-based hybrid plasmonic waveguides
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:1, s. 480-484
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid plasmonic waveguides based on a surface oxidized dielectric nanowire placed on a metal surface can facilitate simultaneously deep subwavelength mode confinement and large propagation length. Directional coupling based on such waveguides are theoretically investigated. Much lower crosstalk is noticed for such hybrid plasmonic waveguides compared to conventional waveguides based on bare dielectric nanowires. Some modifications, such as vertically placing the metal surfaces or using a metallic block between the nanowires, are studied which can further reduce the crosstalk between two waveguides. The proposed low crosstalk structures based on hybrid plasmonic waveguides can provide a simple platform for plasmonic integration which can at the same time easily interface with traditional photonic circuits. (C) 2010 Elsevier B.V. All rights reserved.
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| 15. |
- Tjärnhage, Torbjörn, et al.
(författare)
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Development of a laser-induced breakdown spectroscopy instrument for detection and classification of single particle aerosols in real-time
- 2013
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Ingår i: Optics Communications. - Amsterdam : Elsevier. - 0030-4018 .- 1873-0310. ; 296, s. 106-108
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Tidskriftsartikel (refereegranskat)abstract
- Detection of aerosolized biological warfare agents by means of LIBS commonly operate with pulsed lasers running at constant repetition rate, resulting in very low hit rates. In this paper, we present a prototype where the LIBS laser is only fired if a particle is expected in the focal zone. A significantly improved hit rate for detection and classification of μm sized single particles in real-time is achieved. Hit rates of 40% and 70% for NaCl particles of sizes 3 and 7.0μm, respectively, can be reached in triggered configuration, as compared to 1% and 2% when the laser is un-triggered.
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| 16. |
- Udalcovs, Aleksejs, et al.
(författare)
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Power efficiency of WDM networks using various modulation formats with spectral efficiency limited by linear crosstalk
- 2014
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 318, s. 31-36
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Tidskriftsartikel (refereegranskat)abstract
- Small channel spacing in WDM systems offers very good spectral efficiency, but may reduce the transparent optical reach because of interchannel crosstalk. In turn, an increase in the network power consumption can be expected, due to the need for signal regeneration. This paper explores the trade-off between spectral efficiency, transparent optical reach, and power consumption. The results confirm that using the most energy efficient transponder (i.e., in terms of W/bps) does not always guarantee the lowest overall network power consumption. This is especially true over long point-to-point distances (i.e., multiple transmission fiber spans) where, in order to ensure stringent quality of transmission levels together with high spectral efficiency, the optical signal needs to be regenerated many times.
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| 17. |
- Wang, Jing, et al.
(författare)
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High-Q photonic crystal surface-mode cavities on crystalline SOI structures
- 2010
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:11, s. 2461-2464
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Tidskriftsartikel (refereegranskat)abstract
- High-Q side-coupled surface-mode cavities in two-dimensional (2D) photonic crystals on crystalline silicon-on-insulator (SOI) structures are demonstrated. One of the surface-mode cavities has the measured system Q factor and intrinsic Q factor of 6200 and 13,400, respectively. The experimental results show that the value of system Q factor is ten times and the intrinsic Q factor six times higher than those of similar structures on amorphous SOI structures, respectively, due to the intrinsic material loss is much lower for crystalline silicon. The Q factors of cavities can be further improved by spin-on-glass overlayers, for increasing the structural symmetry. After the spin-on-glass process, the system Q factor and the intrinsic Q factor become nearly twice higher. Meanwhile, the drop wavelengths are largely red-shifted. (C) 2010 Elsevier B.V. All rights reserved.
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| 18. |
- Wang, Ke, et al.
(författare)
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100 Gb/s RZ-OOK transmission through 212 km deployed SSMF using monolithically integrated ETDM receiver module
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:3, s. 782-786
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Tidskriftsartikel (refereegranskat)abstract
- 100 Gb/s on-off keying (OOK) transmission over 212 km installed standard single-mode fibers using an Indium Phosphide (InP)-based electrical clock-data-recovery (CDR) and demultiplexer module was demonstrated 5 5 x 10(-11) bit error rate (BER) performance was achieved and 11 dB optical signal-to-noise ratio (OSNR) penalty was required at 10(-9) BER after transmission
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| 19. |
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| 20. |
- Xu, Tianhua, et al.
(författare)
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Carrier phase estimation methods in coherent transmission systems influenced by equalization enhanced phase noise
- 2013
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 293, s. 54-60
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Tidskriftsartikel (refereegranskat)abstract
- We present a comparative study on three carrier phase estimation algorithms, including a one-tap normalized least mean square (NLMS) method, a block-average method, and a Viterbi-Viterbi method in the n-level phase shift keying coherent transmission systems considering the equalization enhanced phase noise (EEPN). In these carrier phase estimation methods, the theoretical bit-error-rate floors based on traditional leading-order Taylor expansion are compared to the practical simulation results, and the tolerable total effective linewidths (involving the transmitter, the local oscillator lasers and the EEPN) for a fixed bit-error-rate floor are evaluated with different block sizes, when the fiber nonlinearities are neglected. The complexity of the three carrier phase estimation methods is also discussed. We find that the carrier phase estimation methods in practical systems should be analyzed based on the simulation results rather than the traditional theoretical predictions, when large EEPN is involved. The one-tap NLMS method can always show an acceptable behavior, while the step size is complicated to optimize. The block-average method is efficient to implement, but it behaves unsatisfactorily when using a large block size. The Viterbi-Viterbi method can show a small improvement compared to the block-average method, while it requires more computational complexity.
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| 21. |
- Xu, Tianhua, 1984-, et al.
(författare)
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Normalized LMS digital filter for chromatic dispersion equalization in 112-Gbit/s PDM-QPSK coherent optical transmission system
- 2010
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:6, s. 963-967
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Tidskriftsartikel (refereegranskat)abstract
- High bit rates optical communication systems pose the challenge of their tolerance to linear and nonlinear fiber impairments. Coherent optical receivers using digital signal processing techniques can mitigate the fiber impairments in the optical transmission system, including the chromatic dispersion equalization with digital filters. In this paper, an adaptive finite impulse response filter employing normalized least mean square algorithm is developed for compensating the chromatic dispersion in a 112-Gbit/s polarization division multiplexed quadrature phase shift keying coherent communication system, which is established in the VPI Simulation platform. The principle of the adaptive normalized least mean square algorithm for signal equalization is analyzed theoretically, and at the meanwhile, the taps number and the tap weights in the adaptive finite impulse response filter for compensating a certain fiber chromatic dispersion are also investigated by numerical simulation. The chromatic dispersion compensation performance of the adaptive filter is analyzed by evaluating the behavior of the bit-error-rate versus the optical signal-to-noise ratio, and the compensation results are also compared with other present digital filters.
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| 22. |
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| 23. |
- Zhu, Kun, et al.
(författare)
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All-optical coherence-free microwave filter with switchable passbands based on phase and intensity hybrid modulation
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:1, s. 140-143
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Tidskriftsartikel (refereegranskat)abstract
- A simple all-optical coherence-free microwave notch filter is proposed and experimentally demonstrated. The filter with switchable passbands is based on a single-wavelength optical source and phase-intensity hybrid modulation scheme. The DC bias voltage applied to the Mach-Zehnder intensity modulator can be adjusted to switch signs of the tap coefficients, which affect the baseband response. Both lowpass and bandpass filtering responses are observed in the experiment and agree well with the simulated results.
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| 24. |
- Hansson, Tobias, 1983, et al.
(författare)
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Self-similar collapse and blow up of laser beams in nonlinear Kerr media-Revisited
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 284:13, s. 3422-3427
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Tidskriftsartikel (refereegranskat)abstract
- Some features of the blow up and collapse phenomena characteristic of the focusing nonlinear Schrodinger equation are discussed. Particular attention is given to recently found solutions describing self-similar collapse in the form of ring-shaped structures. The characteristic parameters of such collapsing rings are found and particular single-humped initial conditions giving rise to ring formation are also discussed. The possibility of self-similarly collapsing beams with parabolic intensity profiles is investigated and used to infer the blow up distance of initially Gaussian beams. The result is shown to be in good agreement with previous empirical results for the blow up distance. (C) 2011 Elsevier B.V. All rights reserved.
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| 25. |
- Mahmmoud Sayed, Abd El-sadek, et al.
(författare)
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Influence of different stabilizers on the optical and nonlinear optical properties of CdTe nanoparticles
- 2011
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Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018. ; 284:12, s. 2900-2904
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Tidskriftsartikel (refereegranskat)abstract
- CdTe semiconductor nanocrystals were synthesized with three different stabilizers: Mercaptoacetic Acid (MM), Mercaptopropionic Acid (MPA) and 2-Mercaptoethanol (ME) at pH approximate to 11.2 by wet chemical route using potassium tellurite and cadmium chloride as starting materials. The effect of capping agent on the preparation of these samples was evaluated using UV-Visible absorption and photoluminescence analysis. With the same reaction time but with different stabilizers, nanocrystals of different diameters were obtained. The average full width at half maximum of the photoluminescence spectra was about 69 nm which indicates that the monodispersity was quite good. The particle size was calculated by Debye-Scherrer equation from XRD data. Further characterization studies such as FT-IR and optical nonlinearity studies on the samples were carried out and the results are discussed. (C) 2011 Elsevier B.V. All rights reserved.
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