VCSEL-multimode optical fiber based links is the most successful optical technology in Data Centers. Laser-optimized multimode optical fibers, OM3 and OM4, have been the primary choice of physical media for 10 G serial, 4 x 10 G parallel, 10 x 10 G parallel, and 4 x 25 G parallel optical solutions in IEEE 802.3 standards. As the transition of high-end servers from 10 Gb/s to 40 Gb/s is driving the aggregation of speeds to 40 Gb/s now, and to 100 Gb/s and 400 Gb/s in near future, industry experts are coming together in IEEE 802.3bs 400 Gb/s study group and preliminary discussion of Terabit transmission for datacom applications has also been commenced. To meet the requirement of speed, capacity, density, power consumption and cost for next generation datacom applications, optical fiber design concepts beyond the standard OM3 and OM4 MMFs have a revived research and developmental interest, for example, wide band multimode optical fiber using multiple dopants for coarse wavelength division multiplexing; multicore multimode optical fiber using plural multimode cores in a single fiber strand to improve spatial density; and perhaps 50 Gb/s per lane and few mode fiber in spatial division multiplexing for ultimate capacity increase in far future. This talk reviews the multitude of fiber optic media being developed in the industry to address the upcoming challenges of datacom growth. We conclude that multimode transmission using low cost VCSEL technology will continue to be a viable solution for datacom applications.
With advancements in optical fiber technology, the incorporation of multiple sensing functionalities within a single fiber structure opens the possibility to deploy dielectric, fully distributed, long-length optical sensors in an extremely small cross section. To illustrate the concept, we designed and manufactured a multicore optical fiber with three graded-index (GI) multimode (MM) cores and one single mode (SM) core. The fiber was coated with both a silicone primary layer and an ETFE buffer for high temperature applications. The fiber properties such as geometry, crosstalk and attenuation are described. A method for coupling the signal from the individual cores into separate optical fibers is also presented.
Improvements to a ground-based 40W 1.55 micron uplink transmitter for the Lunar Laser Communications
Demonstration (LLCD) are described. The transmitter utilizes four 10 W spatial-diversity channels to broadcast 19.4 -
38.9 Mbit/s rates using a variable-duty cycle 4-ary pulse position modulation. At the lowest rate, with a 32-to-1 duty
cycle, this leads to 320 W peak power per transmitter channel. This paper discusses a simplification of the transmitter
that uses super-large-area single mode fiber and polarization control to mitigate high peak power nonlinear impairments.
Graded index HCS(GI-HCS) optical fibers are designed with unique features for computer networks in automation and
process control, such as Ethernet, in an industrial environment. We demonstrated for the first time 1Gb/s transmission
over 700m of a GI-HCS optical fiber with a 62.5 μm core and 200 μm clad. The transceiver used is an off-the-self
Gigabit Ethernet VCSEL transceivers for multimode optical fiber. The field- terminated crimp and cleave connectors
were found to have no detrimental effect.
Development of Er and ErYb doped fibers for high performance Er-doped fiber
amplifiers (EDFA) and high power fiber lasers is reviewed. Fiber design optimization for
applications including wide flat gain spectrum, and high power conversion efficiency are
discussed. Major parameters such as fiber gain spectrum consistent and uniformity for volume
production are presented. In addition, some of nonlinear effects in EDFA for modern optical
communication network will be discussed.
Recent laboratory experiments have demonstrated that distributed Raman amplification, advanced modulation formats, optimized dispersion maps, and forward error correction are key technologies for 10-Gb/s and 40-Gb/s DWDM terrestrial transmission over 2000 to 6000 km. The transmission fiber's Raman gain efficiency and dispersion properties are thus important parameters. Future high-bit-rate, high-capacity installed systems will require advanced transmission fibers to extend their reach to at least 2000 km, a distance also specified by a high-profile U.S. government optical networking project. This paper will address a number of the enabling fiber properties, including dispersion, dispersion slope, Raman gain efficiency, and polarization mode dispersion. In addition, several recent experiments will be reviewed, including demonstrations of high-spectral-efficiency terrestrial transmission at 10 Gb/s and 40 Gb/s over 4000 km and 3200 km, respectively, and 10-Gb/s transmission over 2400 km using 200-km spans.
As system architectures are pushed to the limit to provide ever-increasing capacities, 40-Gb/s DWDM appears to be the next technology that will be commercially deployed. This paper reviews some of the key enabling technologies for high capacity 40-Gb/s transmission, including distributed Raman amplification, new optical fibers, advanced modulation formats, and forward error correction. It will also explain system design trade-offs and discuss several recent large-scale system transmission experiments for multiple terabit ultra-long haul terrestrial networks.