Showing papers by "Samir Ghalmi published in 2003"
TL;DR: In this paper, the authors compare various techniques to measure multipath interference (MPI) in devices exhibiting distributed coherent crosstalk, and show that slow temporal intensity variations of a continuous-wave distributed-feedback laser yields the best measure of MPI in few-mode fiber devices.
Abstract: We compare various techniques to measure multipath interference (MPI) in devices exhibiting distributed coherent crosstalk. A notable example of devices in this class is the higher order mode dispersion compensator. These devices are susceptible to deterministic noise as well as intermittent fading, and the measurement technique employed must capture both these manifestations of MPI. We show that, ultimately, slow temporal intensity variations of a continuous-wave distributed-feedback laser yields the best measure of MPI in few-mode fiber devices.
85 citations
TL;DR: In this article, a tunable dispersion compensator that utilizes higher order mode fibers and switchable fiber gratings is presented, which is free from tradeoffs between tuning range and bandwidth.
Abstract: We demonstrate a novel tunable dispersion compensator that utilizes higher order mode fibers and switchable fiber gratings. The device is broad band and wavelength continuous, yielding a bit rate, bit format, and signal bandwidth as well as channel-spacing transparent adjustable dispersion compensator. The novel device design is free from tradeoffs between tuning range and bandwidth. The tuning range is 435 ps/nm, with a bandwidth of 30 nm. Its all-fiber configuration yields the lowest loss (average /spl sim/3.7 dB) tunable dispersion compensator reported to date. 40-Gb/s transmission tests reveal penalty-free operation.
39 citations
TL;DR: In this article, a technique for measuring the chromatic dispersion of the higher-order mode of an optical fiber was proposed, which is simple, accurate, and capable of measuring the dispersion length of fiber without the need for mode converters.
Abstract: We present a novel technique for measuring the chromatic dispersion of the higher order mode of an optical fiber. The measurement technique is simple, accurate, and capable of measuring the dispersion of kilometer lengths of fiber without the need for mode converters. The dispersion of the LP/sub 02/ mode is measured for several different fibers, and accuracies of better than 1%, compared with a measurement with the modulation phase shift method, are achieved.
23 citations
TL;DR: In this paper, a resonant grating coupler with the broadest bandwidth (565 nm) reported to date, using microbend gratings in dispersion-optimized few-mode fibers, is presented.
Abstract: We demonstrate resonant grating couplers with the broadest bandwidth (565 nm) reported to date, using microbend gratings in dispersion-optimized few-mode fibers. Control of modal dispersion enables the demonstration of spectrally flat (< 0.25-dB ripple) coupling. This enables a compact (1 cm), broad-band (110 nm) variable optical attenuator, which is highly cost-effective, since device assembly simply involves pressing an as-drawn fiber between two corrugated blocks.
17 citations
23 Mar 2003
TL;DR: This work compares various techniques to measure MPI in devices exhibiting distributed coherent crosstalk, finding that slow temporal intensity variations of a CW DFB laser captures most of the relevant information.
Abstract: We compare various techniques to measure MPI in devices exhibiting distributed coherent crosstalk. Such devices are susceptible to deterministic noise as well as intermittent fading, and the measurement technique employed must capture both these manifestations of MPI. We evaluate several measurement techniques used to characterise MPI in few mode fibers. The coherent, distributed nature of MPI in few-mode fibers leads to fast fluctuations, manifesting in deterministic noise, as well as slow variations, reminiscent of fading in mobile communications systems. Slow temporal intensity variations of a CW DFB laser captures most of the relevant information.
8 citations
Proceedings Article•
01 Jun 2003
Abstract: Resonant couplers, such as long-period fiber-gratings (LPG) induce coupling between two copropagating modes in a fiber by phase-matching the relevant modes. While this process enables arbitrarily strong coupling and can even be the spectra are highly wavelength dependent, since phase is a wavelength dependent quantity. In this paper, we report the demonstration of microbend-induced LPGs in a specially designed few-mode fiber, with record 3 d B bandwidths of 565 nm. The coupling is spectrally flat over a bandwidth of 110 nm. This is enabled by a unique fiber design that allows simultaneously matching the phase, group delay, dispersion as well as the dispersion slope of two modes. This feature is utilised to demonstrate broadband, spectrally flat VOAs, with continuous tunability from 0-10 dB. The spectral characteristics of LPGs that couple the LPol and LPll modes can be described by a detuning parameter 8
4 citations
23 Mar 2003
TL;DR: This work presents a study of loss and MPI contributions from various components in adjustable dispersion compensators utilizing HOM fibers and demonstrates technology scalability to offer fine dispersion tuning granularity while maintaining low loss and low MPI characteristics.
Abstract: We present a study of loss and MPI contributions from various components in adjustable dispersion compensators utilizing HOM fibers. We demonstrate this technology scalability to offer fine dispersion tuning granularity while maintaining low loss and low MPI characteristics.
3 citations
23 Mar 2003
TL;DR: In this paper, a technique for measuring the chromatic dispersion of the higher order modes in kilometer lengths of fiber is presented, and accuracies better than 1% are achieved.
Abstract: We present a technique for measuring the chromatic dispersion of the higher order modes in kilometer lengths of fiber. The LP/sub 02/ dispersion is measured for several different fibers, and accuracies better than 1% are achieved.
2 citations