| 1. |
- Bakke, T., et al.
(författare)
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Polymeric optical spot-size transformer with vertical and lateral tapers
- 2002
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 20:7, s. 1188-1197
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Tidskriftsartikel (refereegranskat)abstract
- The design, fabrication, and characterization of a polymeric optical spot-size transformer with vertical and lateral tapers is reported. The vertical taper is formed by utilizing the planarization properties of a polymer, while the lateral taper is defined by photolithography. An optimization method for the taper shape is described based on fundamental results from coupled local mode theory. A total fiber to waveguide insertion loss of 0.6 dB has been measured with the integration of the transformer, an improvement of 2.1 dB. The spatial alignment tolerance for 1 dB excess loss was measured to ±2.7 µm, consistent with theory.
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| 2. |
- Carlsson, C., et al.
(författare)
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Analog modulation properties of oxide confined VCSELs at microwave frequencies
- 2002
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 20:9, s. 1740-1749
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Tidskriftsartikel (refereegranskat)abstract
- Motivated by the need for affordable, high-performance fiber-optic microwave links in fiber-fed microcellular networks and radar systems, we have performed a comprehensive experimental evaluation of the microwave modulation characteristics of high-speed oxide-confined vertical cavity surface emitting lasers (VCSELs) emitting at 840 inn. VCSELs with different oxide aperture diameters, including both single- and multimode lasers, have been used to track the dependence on modal behavior. The study includes both static and dynamic characteristics, with an emphasis on those of major importance for analog modulation. This includes the small-signal modulation response (S-11 and S-21), the relative intensity noise (RIN), and the intermodulation distortion. From this, we determine the spurious free dynamic range, the impedance characteristics, and the speed limitations.
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| 3. |
- Carlsson, Christina, 1975, et al.
(författare)
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RF transmission over multimode fibers using VCSELs-comparing standard and high bandwidth multimode fibers
- 2004
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 22:7, s. 1694-1700
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Tidskriftsartikel (refereegranskat)abstract
- Fiber-optic radio-frequency links have been assembled using oxide-confined vertical-cavity surface-emitting lasers (VCSELs) and multimode fibers. Links with single and multimode VCSELs and with standard and high-bandwidth fibers have been evaluated and compared in the frequency range of 0.1-10 GHz. The best results were obtained for links with a multimode VCSEL and a high-bandwidth fiber. For a 500-m-long link, a spurious free dynamic range of 104 dB. HZ(2/3) at 2 GHz and 100 dB (.) Hz(2/3) at 5, GHz were obtained while allowing for a VCSEL-fiber misalignment of +/-12 mum. Corresponding numbers for the intrinsic link gain and noise figure are -29 and -33 dB, and 39 and 42 dB at 2 and 5 GHz, respectively. Inferior performance Was observed for the standard fiber link due to a larger variation in modal group velocities. This paper also presents a detailed link analysis to identify performance limitations and to suggest modifications for improved performance.
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| 4. |
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| 5. |
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| 6. |
- Hedekvist, Per Olof E, 1967, et al.
(författare)
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Microwave Harmonic Frequency Generation utilizing the properities of an Optical Phase Modulator
- 2004
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 22:3, s. 882-886
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Tidskriftsartikel (refereegranskat)abstract
- New techniques to generate a harmonic microwave frequency modulated on an optical carrier are presented. All these techniques utilize the polarization-dependent properties of a LiNbO3-phase modulator and manage to achieve 40-GHz modulation using only 10-GHz electronics. The signal quality of the generated frequency is mainly determined by the 10-GHz signal generator, and the suppression of undesired lower order harmonic frequencies exceeds 30 dB.
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| 7. |
- Hellström, E., et al.
(författare)
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Third-order dispersion compensation using a phase modulator
- 2003
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 20:5, s. 1188-1197
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Tidskriftsartikel (refereegranskat)abstract
- Compensation of third-order dispersion in a fiber-optic transmission system using a phase modulator is studied both theoretically and experimentally. A sinusoidal signal is used as modulation function, where the amplitude and phase delay are optimized. The 2-ps input pulses (160-Gb/s compatible) were transmitted through a 626-km fiber link, where the characteristic oscillating tail was measured with a 1.6-ps resolution optical sampling system. When applying the phase modulation, the oscillating tail was significantly suppressed. The pulses were also used in a 160-Gb/s transmission experiment, where the eye diagrams were measured with the sampling system. Numerical simulations and practical experiments showed excellent agreement.
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| 8. |
- Jamid, H. A., et al.
(författare)
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A new higher order finite-difference approximation scheme for the method of lines
- 2001
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 19:3, s. 398-404
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Tidskriftsartikel (refereegranskat)abstract
- A new 5-point and a 7-point nonuniform mesh finite-difference scheme is introduced to approximate the second-derivative operator. The scheme is applied using the method of lines. The necessary interface conditions for the TE and TM fields at an index discontinuity are appropriately included in the derivation. This scheme can model lossy dielectrics as well as metallic layers in a unified way. Numerical results are given for the fundamental TE and TM modes of a high-contrast waveguide and for a metal/dielectric single interface TM surface-plasmon mode showing excellent convergence behavior to the analytical results.
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| 9. |
- Jamid, H. A., et al.
(författare)
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Analysis of deep waveguide gratings : an efficient cascading and doubling algorithm in the method of lines framework
- 2002
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 20:7, s. 1204-1209
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a computationally fast, numerically stable, and memory-efficient cascading and doubling algorithm is proposed within the method of lines framework to model long planar waveguide gratings having thousands of periods in the propagation direction. This algorithm can model 2(n) grating periods in n calculational steps and needs N-2 matrices for N sample points in the problem space. It can model periodic, quasi-periodic, symmetric, and asymmetric, gratings efficiently. Different deep waveguide gratings are modeled using this scheme and results for the fundamental TE mode spectral reflectivity are compared with published results showing excellent agreement.
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| 10. |
- Karlsson, Magnus, 1967, et al.
(författare)
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Long-term measurement of PMD and polarization drift in installed fibers
- 2000
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 18:7, s. 941-951
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Tidskriftsartikel (refereegranskat)abstract
- We report the most detailed long-term measurement of polarization mode dispersion (PMD) made to date. We measured two separate fibers under the same time period, which makes it possible to compare the drift properties of two similar fibers in the same environment. The measured Jones matrices suffers from both random and systematic errors, a generic problem which we discuss in detail and solve. The results confirmed the well-known statistical properties of the PMD-vector. Furthermore, the drift averaged over wavelength is very well (96%) correlated between the two fibers. We finally quantified the temporal drift by computing the autocorrelation function of the PMD-vector analytically, both with respect to wavelength and to drift time. The analytical theory shows good agreement with the measurements.
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