| 11. |
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| 12. |
- Smilgevicius, V., et al.
(författare)
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Noncollinear optical parametric oscillator with periodically poled KTP
- 2000
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Ingår i: Optics Communications. - 0030-4018 .- 1873-0310. ; 173:06-jan, s. 365-369
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate efficient noncollinear low-threshold optical parametric oscillation in periodically poled KTP crystal pumped by the second harmonic of the Q-switched Nd:YAG laser. The noncollinear geometry provides an angular frequency tuning at fixed temperature.
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| 13. |
- Usachev, P., et al.
(författare)
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Experimental verification of differences between classical and quantum polarization properties
- 2001
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Ingår i: Optics Communications. - 0030-4018 .- 1873-0310. ; 193:06-jan, s. 161-173
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Tidskriftsartikel (refereegranskat)abstract
- We have carried out polarization measurements on a two-photon quantum state generated by spontaneous parametric down conversion. Our measurements show that the state is unpolarized in the classical theory, but they also show that the state is not invariant under geometric rotation. Therefore, it is not unpolarized in the quantum theory. This is another example of a rather simple experiment that clearly shows the effects of quantum interference. It also confirms the theoretical investigation by Klyshko [Phys. Lett. A 163 (1992) 349]. The experiment is explained theoretically and a systematic treatment of polarization in quantum theory is outlined.
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| 14. |
- Visser, T. D., et al.
(författare)
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Phase-space inequality for partially coherent optical beams
- 2001
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Ingår i: Optics Communications. - 0030-4018 .- 1873-0310. ; 187:03-jan, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- A phase-space inequality is derived for beams of arbitrary state of spatial coherence. It applies to the product of a factor which expresses the effective coherence area of the source that generates the beam and the effective angular spread of the beam; and, by analogy with coherent beams, it may be regarded as a measure of the beam quality. It is found that the factor attains a minimum for the entire class of Gaussian Schell-model beams (which include the Hermite Gaussian laser mode).
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| 15. |
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| 16. |
- Abeywickrama, Sandu, et al.
(författare)
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Protecting core networks with dual-homing: A study on enhanced network availability, resource efficiency, and energy-savings
- 2016
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Ingår i: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 381, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- Core network survivability affects the reliability performance of telecommunication networks and remains one of the most important network design considerations. This paper critically examines the benefits arising from utilizing dual-homing in the optical access networks to provide resource-efficient protection against link and node failures in the optical core segment. Four novel, heuristic-based RWA algorithms that provide dedicated path protection in networks with dual-homing are proposed and studied. These algorithms protect against different failure scenarios (i.e. single link or node failures) and are implemented with different optimization objectives (i.e., minimization of wavelength usage and path length). Results obtained through simulations and comparison with baseline architectures indicate that exploiting dual-homed architecture in the access segment can bring significant improvements in terms of core network resource usage, connection availability, and power consumption.
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| 17. |
- Aghamiri, Seyed Mohammadreza, et al.
(författare)
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Effect of gamma irradiation on the light polarization variation of PMMA polymer
- 2008
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Ingår i: Optics Communications. - : Elseevier. - 0030-4018 .- 1873-0310. ; 281:3, s. 356-359
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Tidskriftsartikel (refereegranskat)abstract
- Analyzing the effect of ionized gamma irradiation on the optical parameters of materials is a solution for finding newer techniques in the field of detector and dosimeter systems. A PMMA (polymethylmethacrylate) polymer was radiated from a 60Co source with a power of 1800 C and a constant dose rate of 1.44 kGy/h in three steps of 5, 25 and 61.2 kGy. The ionized gamma irradiation affected the refractive index of polymer and therefore it changes the polarization of the incident light. The difference in the polarization phase shift of the polymer depended on the dose it had been irradiated with.
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| 18. |
- 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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| 19. |
- 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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| 20. |
- 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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