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We report wavelength-division-multiplexed transmission of ninety 128-Gb/s polarization-multiplexed quadrature-phase-shift-keyed channels in a seamless 73 nm band over 60 × 100 km of ultra-large-area fiber. Co- and counter-pumped all-Raman amplification in the fiber spans, single-stage discrete Raman amplifiers, and broadband wavelength selective switch and channel equalizer were utilized to achieve optical signal-to-noise-ratio margin of more than 3 dB after 6000 km transmission of the 9 Tb/s capacity.

We discuss the advantages of spatial superchannels for future terabit networks based on space-division multiplexing (SDM), and demonstrate reception of spatial superchannels by a coherent receiver utilizing joint digital signal processing (DSP). In a spatial superchannel, the SDM modes at a given wavelength are routed together, allowing a simplified design of both transponders and optical routing equipment. For example, common-mode impairments can be exploited to streamline the receiver's DSP. Our laboratory measurements reveal that the phase fluctuations between the cores of a multicore fiber are strongly correlated, and therefore constitute such a common-mode impairment. We implement master-slave phase recovery of two simultaneous 112-Gbps subchannels in a seven-core fiber, demonstrating reduced processing complexity with no increase in the bit-error ratio. Furthermore, we investigate the feasibility of applying this technique to subchannels carried on separate single-mode fibers, a potential transition strategy to evolve today's fiber networks toward future networks using multicore fibers.

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.

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.

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.

We use a novel fiber-grating device to demonstrate the first polarization-insensitive all-fiber higher order mode dispersion compensator for broad-band dispersion compensation. Its low loss and high effective area have enabled transmission through 1000 km (10/spl times/100 km) of nonzero dispersion-shifted fiber (NZDSF) at 40 Gb/s.

This letter describes a novel structure and crosstalk characteristics of a graded-index multicore fiber with seven cores arranged in a hexagonal array. A total of 70 Gb/s (7 × 10 Gb/s) is transmitted over a single 100-m seven-core multimode fiber (MMF) using tapered multicore fiber connectors and 850-nm vertical-cavity surface-emitting lasers, demonstrating high-speed multicore MMF transmissions for parallel optical data links.