L. Eskildsen

Interferometric noise in lightwave systems with optical preamplifiers

Penalties from multi-path interference in transmission systems employing optical preamplifiers have been investigated experimentally as well as theoretically. Calculations of the fraction of errors originating from the four possible combinations of received and interfering bit are carried out to identify the dominant cause of the power penalties. With perfect extinction ratio, the penalties from phase noise induced intensity noise (PIIN) are significant only at moderate levels of relative crosstalk (-30 dB to -18 dB), whereas the error floors (infinite penalty) are caused by beat noise originating from crosstalk and amplified spontaneous emission and a reduction in extinction ratio. Nonperfect extinction ratios increases the sensitivity to PIIN.

Unrepeatered WDM transmission experiment with 8 channels of 10 Gb/s over 352 km

Remotely pumped post- and preamplifiers are employed in an 80-Gb/s wavelength-division multiplexed repeaterless transmission system with a transmission distance of 352 km and a fiber loss of 65.3 dB. Low-loss silica-core fiber combined with dispersion compensation in the receiver is used to maximize the transmission distance. The eight channels which range in wavelength from 1552.30 nm to 1559.56 nm exhibit sensitivities between -31.4 dBm and -30.5 dBm for error rates of 10/sup -9/.

465-km repeaterless transmission using a 2.488 Gb/s directly modulated DFB laser

By employing a directly modulated DFB laser at 2.488 Gb/s in a repeaterless transmission system we have transmitted over distances up to 465 km. The system employs remote post- and pre-amplifiers as well as dispersion-compensating fiber. No spectral broadening, except the frequency chirp of the laser, is employed for suppression of stimulated Brillouin scattering.

SBS suppression using a temperature wavelength-modulated laser diode with low residual AM

We report on an efficient method for suppressing stimulated Brillouin scattering (SBS) with negligible residual amplitude modulation (AM) using the temperature tunable properties of a semiconductor laser diode. We demonstrate an effective threshold of 23.4 dBm by applying a 16 V/sub pp/, 5 kHz sinusoid to a thin-film resistor on top of the laser diode. The residual AM is measured to be only 1.2/spl middot/10/sup -4/.

405 km of repeaterless transmission at 5 Gb/s utilizing a post-amplifier and a remotely preamplified receiver with forward error correction

A repeaterless system enables transmission over 405 km of fiber at 5 Gb/s with 24.3 dBm of launch power and a remotely preamplified receiver sensitivity with FEC of -59 dBm for a total span budget of 83.3 dB.

Residual amplitude modulation suppression using deeply saturated erbium-doped fiber amplifiers

Residual amplitude modulation due to wavelength dithering has been reduced significantly. A power penalty of 3.5 dB is reduced to only 0.2 dB by employing a deeply saturated erbium-doped fiber amplifier with a 25-kHz response frequency as a booster amplifier.

465-km, 2.488 Gbit/s repeaterless transmission using a directly modulated DFB laser

Summary form only given. In this work, we experimentally demonstrate repeaterless transmission over distances as long as 465.6 km using a directly modulated distributed feedback (DFB) laser. Suppression of stimulated Brillouin scattering (SBS) is obtained by the frequency chirping of the laser diode itself when modulated without any additional manipulation of the transmitted signal spectrum.