Unrepeatered transmission of 64 × 43 Gb/s PDM-RZ-BPSK channels, spaced by 33 GHz is realized over a record distance of 468 km of low loss and large effective area fiber using a high power booster and a remote amplifier.

We present a 60 × 100 Gb/s unrepeatered transmission experiment at 2.5 b/s/Hz spectral efficiency over a record distance of 437 km of ultra-low loss fibre, with a high power booster and third-order Raman pumping. We also assess the penalty of 40 GHz compared to 50 GHz channel spacing.

We describe a 64 × 43 Gb/s unrepeatered transmission experiment over 440 km of ultra-low loss fiber with third-order Raman pumping. We then compare coherent transmission at 40 Gb/s and 100 Gb/s in unrepeatered conditions.

Low loss and high effective area (135μm2) fibre is combined with powerful third order Raman pumps and remote amplification to span a record 462km long unrepeatered link with four 100Gb/s PDM-QPSK channels and real-time digital processing.

We demonstrate the transmission of 4 channels at 43Gb/s over a record 525km unrepeatered distance using PMD-tolerant and spectrally efficient PDM-RZ-BPSK modulation combined with a coherent receiver, advanced third order Raman and remote amplification technologies and large effective area fibre.

We perform ultra-long unrepeatered transmission at 10 Gb/s, applying the most advanced technology: RZ-DPSK, third-order Raman pumping and ultra-low loss fiber. We transmit four channels over 574 km and one channel over 601 km.

We demonstrate the transmission of 26 channels at 100 Gb/s (corresponding to a total capacity of 2.6 Tb/s) over a 401-km-long unrepeatered link with a spectral efficiency of 2 b/s/Hz. This is obtained thanks to the association of polarization-division-multiplexed quadrature phase-shift keying signals detected in a coherent receiver and an optimized amplification scheme, consisting in high-power booster and third-order remote optically pumped amplifier.

The combination of PDM-QPSK with a coherent receiver and an optimized amplification scheme (high power booster and third order pumped ROPA) enables the transmission of 26 channels at 100Gb/s over a 401km long unrepeatered link.

The Alternate Polarisation-RZ-DPSK modulation format extends the 43 Gb/s unrepeatered transmission distance to 505 km, with E-PSCF fibre, third-order Raman pumping and a remotely-pumped amplifier.

E-PSCF, third-order Raman pumps, remotely-pumped amplifier, NRZ-DPSK transmitter and receiver are used to realize a record 485 km long unrepeatered transmission of 4 WDM channels at 43 Gb/s.

An error-free transmission experiment in bidirectional unrepeatered configuration over 436 km is reported. Particular attention has been paid to Rayleigh backscattering and distributed Raman amplification, enabling us to cover 77 dB span loss.

With a view to improve the power level and brightness of semiconductor pump lasers, we have resorted to a scalable implementation and achieved spectral beam combining through a low-quality-factor external cavity. For that purpose, a high-power single-mode laser array emitting up to 2.1 W at 3.2 A at 980 nm has been realized, which delivers 1.5 W in external cavity. A power of 0.66 W was finally coupled into the single-mode fiber, with a coupling efficiency of 44%. Pumping experiments of an erbium-doped fiber amplifier utilizing this laser have demonstrated efficiency and noise characteristics similar to what is usually obtained with conventional sources, with the noteworthy advantage of a lower gain excursion over the C-band.

A new pump source based on a semiconductor array coupled with an external cavity laser is shown. Its broad output spectrum allows to improve the EDFA gain flatness while reducing manufacturing cost.

We have developed an array of ten uncoupled, single-mode ridge-waveguide lasers for spectral beam combining at 980 rim, which are based on an aluminium-free active region. Single emitters deliver 0.4 W CW at 0.7 A with an M-2 beam quality factor of 1.6. The array has an output power of 2.1 W CW at 3.15 A. The maximum wall-plug efficiency is 48%. Spectral beam combining is achieved through a low-quality-factor external cavity. We extract more than 1.5 W from the cavity with a good beam quality. The ten peak wavelengths range between 968 and 982 rim. The source was validated by pumping an EDFA with similar results as a single wavelength source.

The first WDM unrepeatered demonstration using co-propagating distributed Raman and remotely-pumped amplification both based on third order cascaded pumping is reported. The 525 km distance achieved represents the longest unrepeatered distance ever reported at 10Gb/s.

A numerical model used for the design of cladding-pumped EDFAs has been implemented showing fair agreement with measured power conversion efficiencies. The model takes into account real multimode structure and enables design of ring-doping EDFA