Showing papers by "Mohammed N. Islam published in 1994"
TL;DR: Researchers in optics and photonics dream of making bandwidth an inexpensive, virtually limitless commodity, so that they will be able to tailor applications to optimize their functionality without regard to bandwidth.
Abstract: Remember when we optimized our computer programs to minimize the memory usage, even at the expense of readability of the code? Now, with an abundance of memory, we no longer worry about the memory requirements. Remember when we minimized the gate count in a circuit by using techniques such as Karnaugh maps? Now, with VLSI and ULSI chips, gate count is no longer an issue. Yet in telecommunications many applications still need to be optimized to fit within bandwidth limitations. Researchers in optics and photonics dream of making bandwidth an inexpensive, virtually limitless commodity, so that we will be able to tailor applications to optimize their functionality without regard to bandwidth.
29 citations
TL;DR: In this article, the authors show that specially tailored erbium-doped fiber amplifiers (EDFA's) can be useful for short-pulse soliton lasers, switching, and propagation.
Abstract: We show that specially tailored erbium-doped fiber amplifiers (EDFA's) can be useful for short-pulse soliton lasers, switching, and propagation. EDFA properties include group-velocity dispersion, birefringence, doping level, and doping distribution; and changing each of these properties enables novel applications. Polarization-maintaining EDFA's can Re used in erbium-doped fiber lasers to avoid intensity-dependent or temperature-dependent state of polarization. We have demonstrated a passively mode-locked erbium-doped fiber laser that generates nearly transform-limited 320 fs pulses with 40 pJ energy using a polarization-maintaining EDFA near the zero dispersion wavelength and a bulk InGaAsP saturable absorber. Moderately birefringent EDFA's can be used to control the walkoff and interaction between orthogonally polarized solitons in all-optical switches. For example, through numerical simulations, we design an all-optical cascadable logic gate with a fanout of 2.7 and energy contrast of 5.5 based on interactions in a soliton period long EDFA. Furthermore, distributed EDFA's can be used for long-distance soliton propagation to shepherd the pulse using bandwidth-limited gain. For picosecond soliton pulses, we show that soliton self-frequency shift and Gordon-Hans effects limit propagation to below 100 km even for low-dispersion fibers. Bandwidth-limited amplification in EDFA may counteract frequency shift due to the soliton self-frequency shift, while frequency filters may suppress the Gordon-Hans effect. Also, because the gain spectral profile for the three-level EDFA changes with pump intensity, complications arise from pump attenuation, and the corresponding changes in the gain spectral profile along the length of the fiber. >
9 citations
TL;DR: In this article, the authors show that fiber logic gates based on soliton interactions can be shortened to less than a soliton period in length by incorporating erbium-doped fiber amplifiers (EDFA) into the switches.
Abstract: We show that fiber logic gates based on soliton interactions can be shortened to less than a soliton period in length by incorporating erbium-doped fiber amplifiers (EDFA’s) into the switches. For example, we describe an all-optical, cascadable logic gate with a fan-out of 2.7 and energy contrast of 5.5 in a soliton-period-long, moderately birefringent EDFA. We compare two configurations: a distributed amplifier, in which the solitons interact while being amplified, and a discrete amplifier, in which the pulses are amplified before interacting. Although asymmetric walk-off and rapid amplification during interaction may play a role in the distributed amplifier, the primary benefit of introducing EDFA’s appears to be the resulting high pulse intensities.
2 citations
06 Jul 1994