Neal S. Bergano

Transmission of 96×100G pre-filtered PDM-RZ-QPSK channels with 300% spectral efficiency over 10,608km and 400% spectral efficiency over 4,368km

We transmitted 96 × 100 G pre-filtered PDM-RZ-QPSK channels with 300% spectral efficiency over 10,608 km using 52 km spans of 150 μm2 fiber and simple single-stage EDFAs. We also achieved 400% spectral efficiency over 4,368 km using similar techniques.

16QAM transmission with 5.2 bits/s/Hz spectral efficiency over transoceanic distance

We transmit 160 x 100 G PDM RZ 16 QAM channels with 5.2 bits/s/Hz spectral efficiency over 6,860 km. There are more than 3 billion 16 QAM symbols, i.e., 12 billion bits, processed in total. Using coded modulation and iterative decoding between a MAP decoder and an LDPC based FEC all channels are decoded with no remaining errors.

112×112 Gb/s transmission over 9,360 km with channel spacing set to the baud rate (360% spectral efficiency)

We transmit 112×112 Gb/s pre-filtered PDM RZ-QPSK channels with 360% spectral efficiency over 9,360km with the channel spacing set to the baud rate. This results in a record spectral efficiency for transpacific distance.

High spectral efficiency long-haul transmission with pre-filtering and maximum a posteriori probability detection

We propose a high spectral efficiency transmission scheme employing tight pre-filtering and maximum-a-posteriori-probability (MAP) detection. We demonstrate that pre-filtering induced inter-symbol-interference can be effectively compensated with MAP detection after transoceanic transmission.

Spectral efficiency limits of pre-filtered modulation formats

We investigate the spectral efficiency (SE) limit of pre-filtered modulation in optical fiber communication systems. We show that pre-filtering induced symbol correlation generates a modulation with memory and, thus, a higher SE limit than that of the original memoryless modulation. The SE limits of a series of modulation formats with varying number L of correlated symbols producing 50% of the original bandwidth are evaluated, which approach the SE limit of a modulation format with 50% pre-filtering as L --> ∞. We show that the SE limit of a modulation format with L correlated symbols approximates a lower bound for the SE limit of the corresponding pre-filtered format.

Experimental comparison of the RZ-DPSK and NRZ-DPSK modulation formats

The RZ-DPSK and NRZ-DPSK modulation formats were experimentally compared using installed undersea fiber links. Our results show a 1-1.5 dB RZ benefit with optimized RZ modulation depth for both 25-GHz and 33-GHz spaced channels.

Improved Margin in Long-Haul 40 Gb/s Systems Using Bit-Synchronously Modulated RZ-DQPSK

We demonstrated a substantial improvement in FEC margin at 40 Gb/s using bit-synchronously modulated RZ-DQPSK. We transmitted 28×40 Gb/s CRZ-DQPSK channels over 6,550 km with ~2 dB of actual FEC margin, without any PMD compensation.

Transmission of 40 Gb/s WDM signals over 6,250 km of conventional NZ-DSF with >4 dB FEC margin

We successfully transmitted 18/spl times/40 Gb/s RZ-DPSK channels over 6,250 km of non-slope-matched-fibers with >4 dB FEC margin using dispersion-slope compensators at the receiver. We demonstrated that 40 Gb/s DPSK worked as well as 10 Gb/s RZ-OOK for the same spectral efficiency.

Coherent 40 Gb/s transmission with high spectral efficiency over transpacific distance

We experimentally study the reach of coherent 40 Gb/s PDM RZ QPSK transmission at several spectral efficiencies. Transpacific transmission distance at 3.2 bits/s/Hz and record SE-distance product at 2.4 bits/s/Hz are demonstrated.

Achieving high spectral efficiency in long-haul transmission with pre-filtering and multi-symbol detection

We investigate a high spectral efficiency transmission approach employing aggressive pre-filtering and multi-symbol detection. We show that pre-filtering induces symbol correlation thus enabling a higher spectral-efficiency limit than that of the original modulation format. We demonstrate 100G transoceanic transmission at 419% spectral efficiency using this approach.