G. Guekos

Cross-polarization modulation in semiconductor optical amplifiers

The polarization sensitivity of semiconductor optical amplifiers can be assessed in terms of gain or in terms of induced phase shift. Although the former aspect has received a lot of attention, the latter is rarely mentioned in the literature. Nevertheless, this birefringence leading to a rotation of the lightwave polarization at the output of the device may give rise to some interesting or unwanted effects. An optical control of the birefringence can be applied to wavelength conversion, signal regeneration, all-optical switching or gating. In this letter, the variation of the birefringence with input polarization and input power is measured.

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.

5-Gb/s XOR optical gate based on cross-polarization modulation in semiconductor optical amplifiers

We demonstrate a new design for a XOR optical gate operating in the GHz regime using the cross-polarization modulation effect in a semiconductor optical amplifier. Dynamic and optically controlled polarization rotation in the devices is used to control the output power of the device. Static extinction ratio of the order of 20 dB can be obtained. Bit rate doubling at rate of 1.2 and 2.5 Gb/s have been demonstrated.

All-optical AND gate implementation using cross-polarization modulation in a semiconductor optical amplifier

We demonstrate experimentally a new design for an all-optical AND gate operating in the gigahertz regime. The efficiency of this effect was estimated by measuring the conversion coefficients C/sub TE/TM/ and C/sub TM/TE/ indicating the TE to TM mode conversion and vice versa when the amplifier is perturbed with a wavelength tunable control beam. The all-optical gate here described differ from others developed before using semiconductor optical amplifiers in its ability to operate on nondegenerate input signals and to produce an output signal with an independent wavelength from the wavelengths of the input signals.

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.

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.

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.

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.