| 1. |
- Anders, Berntson, et al.
(author)
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Self-phase modulation in dispersion compensated optical fibre transmission systems
- 1996
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 130:1-3, s. 153-162
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Journal article (peer-reviewed)abstract
- An analysis is made of the influence of self-phase modulation on optical fibre communication systems where the chromatic dispersion is compensated for by a dispersion compensation fibre. In particular we derive a simple and useful expression for the optimal fibre length in the presence of nonlinearities.
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| 2. |
- Beck, M., et al.
(author)
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A pulse-train laser driven XUV source for picosecond pump-probe experiments in the water window
- 2001
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In: Optics Communications. - 0030-4018 .- 1873-0310. ; 190:06-jan, s. 317-326
-
Journal article (peer-reviewed)abstract
- We describe the development of a table top soft X-ray source based on a laser produced plasma. The plasma is produced by a Nd:YLF pulse-train laser which delivers pulse trains of up to 400 pulses each of about 25 ps duration, Number and energy of the micropulses are fully computer controlled adjustable for an optimum interaction with a rotating solid target. Spectral, spatial and temporal characteristics of the X-ray emission from Mylar and copper targets have been studied. A calibrated back-illuminated CCD camera together with a slit grating spectrograph were utilized for the measurement of the absolute soft X-ray photon fluxes. The temporal measurements were performed using a streak camera while the plasma size was measured with a zone plate. An application of the system in a X-ray absorption experiment is shown, The advantages of the system in view of possible optical pump and soft X-ray probe experiments will be discussed.
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| 3. |
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| 4. |
- Friberg, Ari T., et al.
(author)
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Focal shifts of converging diffracted waves of any state of spatial coherence
- 2001
-
In: Optics Communications. - 0030-4018 .- 1873-0310. ; 196:06-jan, s. 1-7
-
Journal article (peer-reviewed)abstract
- We analyze the focusing of wave fields of any state of coherence by systems with low Fresnel numbers. We study the optical intensity on the axis in the focal region. The dependence of the focal shift and of the maximum on-axis intensity on the state of coherence is examined for some model fields.
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| 5. |
- Karlsson, G., et al.
(author)
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Q-switching of an Er-Yb : glass microchip laser using an acousto-optical modulator
- 2003
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 217:06-jan, s. 317-324
-
Journal article (peer-reviewed)abstract
- We present a compact Q-switched Er-Yb:glass microchip laser operating at the wavelength of 1.535 mum using an acousto-optical modulator. A Q-switched peak power of 325 W with a pulse-duration of 38 ns and a pulse-to-pulse jitter of less then 10 ns was achieved. Well-controlled pulses were obtained for repetition rates up to 10 kHz while the maximum pulse energy was 12 muJ. The experimental results are compared with theoretical analysis, which shows how to optimize the laser as well as fundamental limitations.
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| 6. |
- Mohan, N.K., et al.
(author)
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Electronic shearography applied to static and vibrating objects
- 1994
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 108:4-6, s. 197-202
-
Journal article (peer-reviewed)abstract
- An optical shearography configuration is presented which can be used for the measurement of slope change for static and vibrating objects in real time. Displacement and vibration amplitude fields are extracted from the shear data, which is an useful property in noise environments. In a Michelson interferometer set-up the two arms are provided with a phase-shift mirror and a bias modulation mirror to carry out the numerical evaluation of the measured deformation. Experimental results for an edge- clamped aluminium plate are presented
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| 7. |
- Norman, P., et al.
(author)
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Two-photon absorption in five-membered heteroaromatic oligomers
- 1999
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In: Optics Communications. - 0030-4018 .- 1873-0310. ; 168:1, s. 297-303
-
Journal article (peer-reviewed)abstract
- Structure-to-property relations for the two-photon absorption intensities of oligothiophenes, oligopyrroles, and oligofurans have been studied using ab initio response theory. Power law dependences of the two-photon absorption intensities with respect to the length of the oligomers have been revealed, and localization lengths at which the intensities are completely dominated by one single state are found.
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| 8. |
- Ostlund, P., et al.
(author)
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Radiometry and far-zone polarization for partially coherent electromagnetic planar sources
- 2001
-
In: Optics Communications. - 0030-4018 .- 1873-0310. ; 197:03-jan, s. 1-8
-
Journal article (peer-reviewed)abstract
- Making use of the rigorous vectorial far-field theory the generalized radiance of a stationary electromagnetic planar source is derived and expressions for the radiant intensity and the radiant emittance are introduced in terms of the spatial coherence properties of the source. A method for calculating the degree of polarization of the field in the far zone of an electromagnetic planar source is put forward and two examples demonstrating the technique are worked out.
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| 9. |
- Paakkonen, P., et al.
(author)
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Partially coherent Gaussian pulses
- 2002
-
In: Optics Communications. - 0030-4018 .- 1873-0310. ; 204:06-jan, s. 53-58
-
Journal article (peer-reviewed)abstract
- The concept of a plane-wave pulse with a Gaussian spectrum and a Gaussian distribution of correlations between different frequency components is introduced. The temporal coherence properties of such a pulse are related to the spectral coherence properties and equivalence relations between pulses with different spectral and temporal correlation parameters are established.
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| 10. |
- Petermann, Ingemar, et al.
(author)
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Limitations of the interferometric side diffraction technique for fibre Bragg grating characterization
- 2002
-
In: Optics Communications. - 0030-4018 .- 1873-0310. ; 201:4-6, s. 301-308
-
Journal article (peer-reviewed)abstract
- We make a quantitative investigation of the interferometric side diffraction technique for characterization of fibre Bragg gratings. As opposed to more commonly used non-interferometric alternatives, this method also allows for determination of the grating's distributed phase. It is shown that for weak gratings the detected power and phase are directly proportional to the amplitude and phase of the refractive index modulation in the fibre. While the phase measurement is only limited by the amount of noise present, the relation between modulation amplitude and detected power becomes non-linear when using small probe beam wavelengths and gratings with a modulation depth Deltan approximate to 10(-3) and above. This behavior is inherent to the side diffraction and thus care has to be taken when performing apodization measurements on very strong gratings. The sensitivity to noise is briefly discussed and using a crude estimate for the noise level. the theory indicates that this method is suitable down to a grating modulation depth of at least Deltan approximate to 10(-5).
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| 11. |
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| 12. |
- Smilgevicius, V., et al.
(author)
-
Noncollinear optical parametric oscillator with periodically poled KTP
- 2000
-
In: Optics Communications. - 0030-4018 .- 1873-0310. ; 173:06-jan, s. 365-369
-
Journal article (peer-reviewed)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.
(author)
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Experimental verification of differences between classical and quantum polarization properties
- 2001
-
In: Optics Communications. - 0030-4018 .- 1873-0310. ; 193:06-jan, s. 161-173
-
Journal article (peer-reviewed)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.
(author)
-
Phase-space inequality for partially coherent optical beams
- 2001
-
In: Optics Communications. - 0030-4018 .- 1873-0310. ; 187:03-jan, s. 1-6
-
Journal article (peer-reviewed)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.
(author)
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Protecting core networks with dual-homing: A study on enhanced network availability, resource efficiency, and energy-savings
- 2016
-
In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 381, s. 327-335
-
Journal article (peer-reviewed)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.
(author)
-
Effect of gamma irradiation on the light polarization variation of PMMA polymer
- 2008
-
In: Optics Communications. - : Elseevier. - 0030-4018 .- 1873-0310. ; 281:3, s. 356-359
-
Journal article (peer-reviewed)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.
(author)
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A short and efficient error correcting code for polarization coded photonic qubits in a dissipative channel
- 2011
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:1, s. 550-554
-
Journal article (peer-reviewed)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.
(author)
-
Stimulated laser induced fluorescence holography for imaging fluorescent species
- 2013
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 311, s. 124-128
-
Journal article (peer-reviewed)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.
(author)
-
Synchronization of spatiotemporal semiconductor lasers and its application in color image encryption
- 2011
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:9, s. 2278-2291
-
Journal article (peer-reviewed)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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| 21. |
- Bhaduri, Basanta, et al.
(author)
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Two wavelength simultaneous DSPI and DSP for 3D displacement field measurements
- 2011
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 284:10-11, s. 2437-2440
-
Journal article (peer-reviewed)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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| 22. |
- Bjurshagen, Stefan, et al.
(author)
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Quasi-three-level Nd:YAG laser under diode pumping directly into the emitting level
- 2006
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 261:1, s. 109-113
-
Journal article (peer-reviewed)abstract
- We present theoretical and experimental investigations on ground-state direct pumping at 869 nm into the emitting level F-4(3/2) of end-pumped quasi-three-level Nd:YAG lasers operating at 946 nm. We have demonstrated, what we believe is for the first time, a Nd:YAG laser at 946 nm directly pumped by diodes and obtained 1.6 W of output power.
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| 23. |
- Björk, Gunnar, et al.
(author)
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Quantum degrees of polarization
- 2010
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:22, s. 4440-4447
-
Journal article (peer-reviewed)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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| 24. |
- Bogdanski, Jan, et al.
(author)
-
Multiuser quantum key distribution over telecom fiber networks
- 2009
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 282:2, s. 258-262
-
Journal article (peer-reviewed)abstract
- We report five-user quantum key distribution (QKD) over switched fiber networks in both star and tree configurations, using the BB84-protocol [1] with phase encoding. Both setups implement polarization insensitive phase modulators, necessary for birefringent single mode fiber (SMF) networks. In both configurations we have achieved transmission distances between 25 km and 50 km with quantum bit error rates between 1.24% and 5.56% for the mean photon number l ¼ 0:1. The measurements have showed feasibility of multiuser QKD over switched fiber networks, using standard fiber telecom components.
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| 25. |
- Bogdanski, Jan, et al.
(author)
-
Sagnac quantum key distribution over telecom fiber networks
- 2009
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 282:6, s. 1231-1236
-
Journal article (peer-reviewed)abstract
- We present a new concept for compensation of single mode fiber (SMF) birefringence effects in a Sagnac quantum key distribution (QKD) setup, based on a polarization control system and a polarization insensitive phase modulator. Our experimental data show stable (in regards to birefringence drift) QKD over 1550 nm SMF telecom networks in Sagnac configuration, using the BB84-protocol [C.H. Bennett, G. Brassard, in: Proceedings of the IEEE International Conference on Computers, Systems, and Signal Processing, Institute of Electrical and Electronic Engineers, New York, 1984, p. 175] with phase encoding. The achieved total Sagnac transmission loop distances were between 100 km and 150 km with quantum bit error rates (QBER) between 5.84% and 9.79% for the mean-photon-number l = 0.1. The distances were much longer and rates much higher than in any other published Sagnac QKD experiments. We also show an example of our one-decoy state protocol implementations (for the 45 km distance between Alice and Bob, corresponding to the 130 km total Sagnac loop length), providing an unconditional QKD security. The measurement results have showed feasibility of QKD over telecom fiber networks in Sagnac configuration, using standard fiber telecom components.
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| 26. |
- Cai, Yangjian, et al.
(author)
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Analytical formula for a decentered elliptical Gaussian beam propagating in a turbulent atmosphere
- 2007
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 271:2, s. 509-516
-
Journal article (peer-reviewed)abstract
- Analytical formulas for the average intensity and decentered parameter of a decentered elliptical Gaussian beam (DEGB) propagating in a turbulent atmosphere are derived in a tensor form. The propagation properties of a DEGB in a turbulent atmosphere are investigated in detail, and found to be different from that in free space. Furthermore, as an application example, we investigate the propagation of a decentered elliptical flat-topped beam (DEFB) by expressing its electric field as a finite sum of DEGBs in a turbulent atmosphere. The properties of a DEGB or a DEFB in a turbulent atmosphere are closely related with the beam's parameters and the structure constant of the turbulent atmosphere.
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| 27. |
- Cai, Yangjian, et al.
(author)
-
Propagation of a hollow Gaussian beam through a paraxial misaligned optical system
- 2006
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 265:2, s. 607-615
-
Journal article (peer-reviewed)abstract
- Based on the generalized diffraction integral formula for treating the propagation of a laser beam through a paraxial misaligned optical system in the cylindrical coordinate system, we obtain an analytical formula for a hollow Gaussian beam passing through a paraxial misaligned optical system. Furthermore, we also obtain the approximate analytical formula for a hollow Gaussian beam passing through a paraxial circularly apertured misaligned optical system by expanding the hard aperture function into a finite sum of complex Gaussian functions. As a numerical example, the propagation properties a hollow Gaussian beam through a misaligned thin lens are studied numerically.
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| 28. |
- Cao, Shun, et al.
(author)
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High-temperature ultra-broad UV–MIR high-efficiency absorber based on double ring-shaped titanium nitride resonators
- 2021
-
In: Optics Communications. - : Elsevier B.V.. - 0030-4018 .- 1873-0310. ; 485
-
Journal article (peer-reviewed)abstract
- An ultrabroad absorber based on double-ring-shaped titanium nitride (TiN) nanoresonators, which can work in high temperatures, is proposed and numerically studied. The absorber with some optimal parameters exhibits an averaged absorption of 94.6% in the range of 200–4000 nm (from ultraviolet to mid-infrared) and a band from 200–3518 nm having an absorption > 90%. We have demonstrated in detail the physical mechanisms of the ultra-broad absorption, including the dielectric lossy property of TiN material itself in shorter wavelengths and plasmonic resonances caused by the metallic property of TiN nano-resonators in longer wavelengths. In addition, the absorber shows polarization independent and wide-angle acceptance. Another absorber with double TiN nano-rings of different heights has flatter and higher absorption efficiency (more than 95% absorption) at 200–2860 nm waveband. These properties make the proposed absorbers based on TiN has great potentials in many applications, such as light trapping, photovoltaics, thermal emitters.
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| 29. |
- Chamaillard, K., et al.
(author)
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Coherency matrix description for statistical linear regression of Stokes parameters in rough small-particle scattering
- 2010
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:22, s. 4519-4524
-
Journal article (peer-reviewed)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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| 30. |
- Chen, R., et al.
(author)
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A low cost surface plasmon resonance biosensor using a laser line generator
- 2015
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 349, s. 83-88
-
Journal article (peer-reviewed)abstract
- Due to the instrument designed by using a common surface plasmon resonance biosensor is extremely expensive, we established a portable and cost-effective surface plasmon resonance biosensing system. It is mainly composed of laser line generator, P-polarizer, customized prism, microfluidic cell, and line Charge Coupled Device (CCD) array. Microprocessor PIC24FJ128GA006 with embedded A/D converter, communication interface circuit and photoelectric signal amplifier circuit are used to obtain the weak signals from the biosensing system. Moreover, the line CCD module is checked and optimized on the number of pixels, pixels dimension, output amplifier and the timing diagram. The micro-flow cell is made of stainless steel with a high thermal conductivity, and the microprocessor based Proportional-Integral-Derivative (PID) temperature-controlled algorithm was designed to keep the constant temperature (25 °C) of the sample solutions. Correspondingly, the data algorithms designed especially to this biosensing system including amplitude-limiting filtering algorithm, data normalization and curve plotting were programmed efficiently. To validate the performance of the biosensor, ethanol solution samples at the concentrations of 5%, 7.5%, 10%, 12.5% and 15% in volumetric fractions were used, respectively. The fitting equation ΔRU=-752987.265+570237.348×RI with the R-Square of 0.97344 was established by delta response units (ΔRUs) to refractive indexes (RI). The maximum relative standard deviation (RSD) of 4.8% was obtained.
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| 31. |
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| 32. |
- Dai, Daoxin, et al.
(author)
-
Reduction of multimode effects in an SOI-based etched diffraction grating demultiplexer
- 2005
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 247:4-6, s. 281-290
-
Journal article (peer-reviewed)abstract
- Multimode effects in the free propagation region (FPR) of a silicon-on-insulator (SOI)-based etched diffraction grating (EDG) demultiplexer are analyzed. In a conventional design, the power coupled to the higher order modes is considerable, which introduces a significant excess loss and crosstalk. It is shown that the multimode effects in an SOI EDG demultiplexer are much more detrimental than in an arrayed waveguide grating demultiplexer. Several methods for reducing the multimode effects are discussed. In particular, a laterally tapered structure between the FPR and the input/output waveguides is proposed as a simple and effective method for reducing the power coupled to the higher order modes and consequently reducing the multimode effects. The taper width is optimized to minimize the crosstalk.
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| 33. |
- Dai, Daoxin, et al.
(author)
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Three-dimensional hybrid modeling based on a beam propagation method and a diffraction formula for an AWG demultiplexer
- 2007
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 270:2, s. 195-202
-
Journal article (peer-reviewed)abstract
- An efficient and accurate three-dimensional (3D) hybrid modeling, which combines a 3D beam propagation method (BPM) and the two-dimensional (2D) Kirchhoff-Huygens diffraction formula, is developed to simulate the field propagation in an arrayed waveguide grating (AWG) dernultiplexer. The 2D Kirchhoff-Huygens diffraction formula is used for the simulation of the light propagation in the free propagation regions (FPRs). A 3D BPM in a polar coordinate system is used to simulate the light propagation in the transition region between the input FPR and the arrayed waveguides so that the coupling coefficients for the arrayed waveguides are calculated conveniently and accurately. For the simulation in the transition region between the arrayed waveguides and the output FPR, only the central arrayed waveguide and several adjacent ones are needed in the computational window of a standard BPM and thus the computation efficiency is improved. Finally, a flat-top AWG is designed and fabricated to verify the reliability of the present simulation method. The calculated and measured spectral responses are in a good agreement.
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| 34. |
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| 35. |
- Dai, D. X., et al.
(author)
-
Novel ultrasmall Si-nanowire-based arrayed-waveguide grating interleaver with spirals
- 2008
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 281:13, s. 3471-3475
-
Journal article (peer-reviewed)abstract
- A novel layout is presented to achieve an ultrasmall arrayed-waveguide grating (AWG) interleaver based on Si-nanowire waveguides. Spiral waveguides are inserted in the middle of arrayed-waveguide to obtain a large lightpath (required for the ultra-high diffraction order) in a small occupied area. A designed ultrasmall AWG interleaver with a free spectral range of 0.8 nm has a total size of only about 73 mu m x 372 mu m (0.027 mm(2)).
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| 36. |
- Dainese, Matteo, et al.
(author)
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Directional coupler wavelength selective filter based on dispersive Bragg Reflection Waveguide
- 2006
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 260:2, s. 514-521
-
Journal article (peer-reviewed)abstract
- A new type of wavelength selective filter, based on high differential dispersion between two coupled waveguides, is presented. The Bragg Reflection Waveguide displays high effective refractive index dispersion, due to the interaction of the guided mode with the two confining Bragg reflectors. When coupled with a weakly guided buried channel silica waveguide, a very narrow bandwidth filter (< 1 nm) can be easily produced, in a shorter length, with respect to directional couplers made with standard step index channel waveguides. The complete design methodology, fabrication and characterization are presented.
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| 37. |
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| 38. |
- Denker, Boris, et al.
(author)
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Yb3+,Er3+:YAG at high temperatures : energy transfer and spectroscopic properties
- 2007
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 271:1, s. 142-147
-
Journal article (peer-reviewed)abstract
- Energy transfer and spectroscopic properties at high temperatures have been investigated in Er,Yb:YAG crystals. It is shown that at elevated temperatures around 600-800 degrees C these characteristics become similar to those in the efficient 1.5 mu m laser medium - Er,Yb-doped phosphate glasses. (c) 2006 Elsevier B.V. All rights reserved.
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| 39. |
- Dong, Hui, et al.
(author)
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Measurement of Mueller matrix for an optical fiber system with birefringence and polarization-dependent loss or gain
- 2007
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 274:1, s. 116-113
-
Journal article (peer-reviewed)abstract
- In an optical fiber system with both birefringence and polarization-dependent loss or gain (PDL/G), a set of input polarization states and their corresponding outputs are deduced to fulfill some general relationships in Stokes space, by considering the fact that the Mueller matrix of such an optical fiber system meets Lorentz transformation. Then, it can be proven that the minimum number of input polarization states is three for an explicit determination of such a Mueller matrix and no independent input parameter is redundant. Based on the theoretical findings, a general and simple approach is proposed to measure the Mueller matrix. The requirements regarding the choices of three inputs are presented for achieving optimum measurement stability and accuracy. Experimental results on an optical fiber system, formed by two 10-km long single-mode fibers with an optical isolator in between, show excellent agreement with the theory.
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| 40. |
- Drummond, Miguel V., et al.
(author)
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All-optical generation of 40 Gb/s single sideband signals using a fiber Bragg grating
- 2010
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 283:12, s. 2492-2495
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Journal article (peer-reviewed)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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| 41. |
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| 42. |
- Fu, H. Y., et al.
(author)
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A tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium
- 2008
-
In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 281:22, s. 5550-5554
-
Journal article (peer-reviewed)abstract
- A novel tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium is proposed, theoretically discussed and experimentally demonstrated. A single-wavelength LD and a modulator (either a Mach-Zehnder modulator or a phase modulator which can avoid the do bias drift problem) are used to obtain a multi-wavelength optical source. By adjusting the modulation frequency and the bias voltage on the modulators, the wavelength spacing and the relative amplitude of the optical tones change, thus making the filter tunable and reconfigurable. The experimental results show that the proposed filters have good tunability and reconfigurability and the mainlobe-to-sidelobe ratio of around 25 dB is achieved.
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| 43. |
- Gong, Y., et al.
(author)
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Crosstalk-aware multiple-AWG based optical interconnects for datacenter networks
- 2018
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 426, s. 151-157
-
Journal article (peer-reviewed)abstract
- This paper proposes a crosstalk-aware passive optical interconnect architecture based on multiple arrayed waveguide gratings (AWGs). With two-stage cascaded AWGs, it can realize the communications not only within but also among the clusters for large-scale datacenters. To overcome serious crosstalk in multiple-AWG based optical interconnects, crosstalk suppression schemes are proposed. Proof-of-concept experiments are carried out to verify the necessity and feasibility of the proposed crosstalk suppression schemes for multiple-AWG based optical interconnects.
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| 44. |
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| 45. |
- He, Zewei, et al.
(author)
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Fabrication of microneedles using two photon-polymerization with low numerical aperture
- 2024
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 553
-
Journal article (peer-reviewed)abstract
- Three-dimensional (3D) micro-nano fabrication through two-photon polymerization (TPP) is a prominent approach for fabricating complex 3D structures. However, the existing techniques face limitations, such as small fabrication area, dependence on high numerical aperture (e.g., oil immersion) objective lenses, which are more expensive. We developed a 780 nm fs laser system integrated with a 2D galvanometer system and Z axis to create a 3D micro-nano printing system. A method to print arbitrarily complex 3D structures while maintaining an extremely high lateral spatial resolution of sub-100nm is proposed by using a cheap low numerical aperture objective lens with the laser power and exposure time precisely controlled. The impact of the laser power and exposure time on the resolution of 3D micro-nano processing is investigated, and we identify the optimal processing environment for achieving the best resolution. The printed linewidth of 62 nm was achieved without the use of an oil immersed objective lens, and only one laser beam was used instead of stimulated emission depletion. Microneedle arrays for animal injection were fabricated using this strategy, which can improve the performance of animal organoid repair. Our results suggest that TPP micro-nano fabrication is an effective method for processing microneedle arrays for biomedical engineering, with the ability to improve the processing resolution with a cheap low numerical aperture objectives lens (e.g., NA = 0.4) through meticulous control of laser power and exposure time. This approach opens up possibilities for affordable and scalable fabrication in sub-100nm structures.
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| 46. |
- Hong, Yuanyuan, et al.
(author)
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Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation
- 2017
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 383, s. 478-484
-
Journal article (peer-reviewed)abstract
- In this paper, a novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed. An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches (WSSs) in an intermediate rack rather than by relaying through optical-electric-optical (O-E-O) conversions. Compared with the conventional O-E-O based approach, the proposed all-optical scheme is able to off-load the traffic at intermediate racks, leading to a reduction of the power consumption and cost. The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats, including both coherently detected and directly detected approaches, are investigated by Monte-Carlo simulations. To enhance the spectrum efficiency (SE), number-of-hop adaptive bandwidth allocation is introduced. Numerical results show that the SE can be improved by up to 33.3% at 40 Gbps, and by up to 25% at 100 Gbps. The impact of parameters, such as targeted bit error rate (BER) level and insertion loss of components, on the transmission performance of the proposed approach are also explored. The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.
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| 47. |
- Högström, Herman, et al.
(author)
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On the angular dependence of gaps in 1-D Si/SiO2 periodic structures
- 2007
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 271:1, s. 148-153
-
Journal article (peer-reviewed)abstract
- A multilayer of silicon and silicon dioxide was used to study the angular dependence of reflectance maxima originating from interference and bulk optical properties. Silicon dioxide has a lattice resonance in the infrared causing an interval of high reflectance for wavelengths around 9 μm. The multilayer was designed such that the interference maxima do not overlap/interact with the material related reflectance maximum. In this way the different angular behavior for the two types of reflectance maxima can be studied simultaneously. Experimental and calculated reflectance spectra for s- and p-polarized light for angles of incidence between 0° and 90° collected for every 5° are presented. The reflectance features caused by interference generally move to shorter wavelengths with increasing angle of incidence, and the materials related peak is widened for (s-polarized light) and excitation of the longitudinal modes was observed for p-polarized light.
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| 48. |
- Islam, A. B. M. Hamidul, et al.
(author)
-
Very low input voltage cascaded travelling wave electroabsorption modulator (CTWEAM) for more than 100 Gbps
- 2013
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 297, s. 43-47
-
Journal article (peer-reviewed)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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| 49. |
- Jalali-Roudsar, Amir Abbas, et al.
(author)
-
Faraday rotation in two-dimensional magneto-optic photonic crystal
- 2005
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In: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 253:1-3, s. 145-150
-
Journal article (peer-reviewed)abstract
- We study the enhancement of Faraday rotation in a two-dimensional square-lattice magneto-optic photonic crystal at optical wavelengths. We show that on incidence of a TM plane wave onto the magneto-optic photonic crystal, high TM-TE mode conversion takes place in the transmission bands of TM and TE fields. The photonic crystal structure increases the average wave path length, which in turn leads to a growth in the polarization rotation. We also show that associated with this phenomenon is a widening of the photonic crystal transmission band.
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| 50. |
- Jaroszewicz, Zbigniew, et al.
(author)
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Spheric long-focal-depth lens : a comment
- 2008
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In: Optics Communications. - : Elsevier. - 0030-4018 .- 1873-0310. ; 281:19, s. 4849-4850
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Journal article (peer-reviewed)
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