A. D'Ottavi

Efficiency and noise performance of wavelength converters based on FWM in semiconductor optical amplifiers

All optical frequency converters are key devices for new-conception optical networks. A theoretical model is presented to evaluate performances of frequencies converters based on highly nondegenerate four-wave mixing (FWM) in semiconductor amplifiers. Conversion efficiency and noise performances are evaluated in generic saturation conditions and compared with experimental results.<<ETX>>

Four-wave mixing in semiconductor optical amplifiers: a practical tool for wavelength conversion

Four-wave mixing in semiconductor optical amplifiers is used to produce wavelength conversion. We report an extended study on the dependence of efficiency and noise on device length, pump power, operation wavelength and conversion interval. The use of longer active regions is a good way to obtain performance as good as requested by the most advanced telecommunication systems.

Low-noise and very high-efficiency four-wave mixing in 1.5-mm-long semiconductor optical amplifiers

Very high four-wave mixing (FWM) efficiency and signal-to-background ratio (SBR) are obtained in a 1.5-mm-long bulk semiconductor optical amplifier. The FWM efficiency is measured to be 5 dB at 1-THz pump-signal detuning, which is the highest value reported to date. With a pump power of -1.4 dBm, the SBR is in excess of 20 dB in a bandwidth of 12.5 GHz, for a pump-signal detuning range as large as 2 THz and the efficiency is under the same conditions larger than -1 dB for a pump-signal detuning range as large as 1 THz. These results make FWM an attractive method for practical wavelength conversion. Some low-detuning measurements show a maximum efficiency around 8 GHz.

Efficiency flattening and equalization of frequency up- and down-conversion using four-wave mixing in semiconductor optical amplifiers

We show that four-wave mixing in semiconductor optical amplifiers with the use of two orthogonally polarized pumps offers the possibility of frequency conversion with constant efficiency over several terahertz. The same two-pump configuration permits one to convert the signal to lower or higher frequencies with the same efficiency.

Wavelength conversion at 10 Gb/s by four-wave mixing over a 30-nm interval

We show that the use of a long semiconductor optical amplifier increases the error-free conversion interval of a four-wave mixing (FWM)-based wavelength converter. 30-nm wavelength down-conversion and 15-nm up-conversion have been obtained at 10 Gb/s. This result is a significant improvement over the previous best performance of a FWM-based wavelength converter and suggests that the full erbium-doped fiber amplifier bandwidth can be covered with FWM wavelength converters.

Mid-span spectral inversion without frequency shift for fiber dispersion compensation: a system demonstration

We report the first demonstration of compensation of optical-fiber dispersion using mid-span spectral inversion without frequency shift by a two-pump four-wave-mixing configuration. We achieve 120 km penalty-free transmission at 2.5 Gb/s over standard single-mode fiber using a directly modulated distributed-feedback laser.

Optical spectral inversion without frequency shift by four-wave mixing using two pumps with orthogonal polarization

We propose a method to obtain spectral inversion of a signal without shifting its frequency. We use four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) with two pumps of orthogonal polarization. A conjugate field is generated with a polarization orthogonal to that of the incoming signal and is selected at the amplifier output by a polarizer. Using a commercially available pig-tailed SOA of 1.5-mm length, we obtain after the polarizer 21.5 dB of intensity ratio between conjugate and amplified incoming signal.

Effects of ultrafast processes on frequency converters based on four-wave mixing in semiconductor optical amplifiers

We show the effect of the ultrafast optical nonlinear interactions on the efficiency of a frequency converter based on four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs). The ultrafast nonlinearities generate a dip of a few decibels in the down-conversion sideband of the conversion efficiency at detuning higher than 1 THz. The frequency detuning at which the minimum occurs depends on the device length and on the pump wavelength. The presence of the minimum of the efficiency affects the design of amplifiers specifically optimized for frequency conversion by FWM.

Frequency-conversion efficiency independent of signal-polarization and conversion-interval using four-wave mixing in semiconductor optical amplifiers

In this letter, we demonstrate that four-wave mixing in semiconductor optical amplifiers, with the use of two orthogonal-polarized pumps in a polarization-diversity scheme, allows frequency conversion with efficiency independent of both signal polarization and conversion interval.

Broad-band polarization-insensitive wavelength conversion at 10 Gb/s

In this letter, we use four-wave mixing in semiconductor optical amplifiers to obtain wavelength conversion of data stream at 10 Gb/s. The wavelength conversion is made independent of polarization and conversion shift by means of a polarization diversity scheme with the use of two pumps proposed in a previous work of ours. The penalty measured is of about 1.2 dB.