S. Scotti

Four-wave mixing in traveling-wave semiconductor amplifiers

The traveling-wave equations of four-wave mixing in semiconductor amplifiers are solved analytically including saturation of the amplifier. Excellent agreement is obtained with numerical solutions of the traveling-wave equations. The analytical model is used to analyze a highly nondegenerate four-wave mixing experiment in a bulk semiconductor amplifier. >

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.

VERY HIGH EFFICIENCY FOUR-WAVE MIXING IN A SINGLE SEMICONDUCTOR TRAVELING-WAVE AMPLIFIER

We report on high efficiency frequency‐conversion obtained by four‐wave mixing in a single traveling‐wave semiconductor optical amplifier. Efficiency in excess of 0 dB is demonstrated for frequency conversion up to 2 THz. Measurements of the signal to the amplified spontaneous emission background ratio are also presented.

4.3 terahertz four‐wave mixing spectroscopy of InGaAsP semiconductor amplfiers

A four‐wave mixing experiment in a bulk InGaAsP traveling‐wave semiconductor amplifier is reported. The maximum pump‐probe detuning is 4.3 THz. The equivalent time resolution of 37 fs is high enough to measure with good accuracy the time constant of spectral‐hole burning (100 fs in our case). The simultaneous presence of spectral‐hole burning and of an instantaneous, within our time resolution, saturation process is clearly displayed.

Investigation of carrier heating and spectral hole burning in semiconductor amplifiers by highly nondegenerate four‐wave mixing

A highly nondegenerate (up to 1 THz) four‐wave mixing experiment is performed in a bulk semiconductor amplifier. The simultaneous presence of carrier heating and spectral hole burning shows up in a four‐wave mixing experiment. A simple physical picture is given that explains the relative weight of the two saturation mechanisms in active semiconductor devices.

Four‐wave mixing efficiency in traveling wave semiconductor optical amplifiers at high saturation

We report an experimental investigation of the conversion efficiency of a frequency converter based on four‐wave mixing in semiconductor optical amplifiers. We find that the maximum of conversion efficiency has a nonlinear dependence on the unsaturated gain of the device. The observed features are explained by the presence of the Auger and bimolecular recombination.

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.

Noise in wavelength conversion using four-wave mixing in semiconductor optical amplifiers

We measure the pump power dependence of efficiency and signal-to-background ratio in wavelength conversion using four-wave mixing in semiconductor optical amplifiers, for different lengths of the device. We show that the efficiency for a 1-mm-long amplifier is about 40 dB larger and the signal-to-noise ratio is about 23 dB larger than for a 0.25 mm amplifier. We also show that, unlike the efficiency, for constant ratio between pump- and signal-power, the signal-to-background ratio monotonically increases with the pump power. We show theoretically that this behavior holds for any range of pump-power values.