Four-wave mixing mediated by the capture of electrons and holes in semiconductor quantum-well laser amplifiers

An experimental technique based on frequency-resolved four-wave mixing is proposed for the investigation of phonon-assisted capture of electrons and holes in electrically pumped semiconductor quantum wells. We show how this technique can be used to directly measure the intrinsic capture lifetime, with no need for involved numerical fits. We also present experimental results from an application of the technique to a multiquantum-well semiconductor optical amplifier. The possible impact of phase matching on the results is discussed

Polarization-dependent optical nonlinearities of multiquantum-well laser amplifiers studied by four-wave mixing

We present a detailed study of the polarization properties of four-wave mixing in multiquantum-well (MQW) semiconductor optical amplifiers (SOA's). In particular, the polarization selection rules relevant to all processes contributing to the generation of the four-wave mixing signal are rigorously derived and discussed. We then show the importance of these results in applications where four-wave mixing is used as a spectroscopic tool to study the optical nonlinearities of semiconductor gain media. For illustration, we demonstrate two novel applications of polarization-resolved four-wave mixing. The first is a new technique for measuring the recombination lifetime in SOA's, based on mixing of a pump wave with polarized amplified spontaneous emission noise. In the second, we use the same polarization selection rules to measure the interwell transport lifetime in alternating-strain MQW amplifiers. Finally, we also discuss the possibility of studying the dynamics of the optically induced phase coherence between spin-degenerate states

Measurement of the stimulated carrier lifetime in semiconductor optical amplifiers by four-wave mixing of polarized ASE noise

We present a simple experiment aimed at measuring the stimulated carrier lifetime in semiconductor optical amplifiers (SOA's). The technique relies on polarization-resolved nearly degenerate four-wave mixing (FWM) of a laser source with an amplified spontaneous emission (ASE) noise source. The method can quickly characterize the bandwidth performance of active layers for application in a cross-gain or cross-phase wavelength converter

Cascaded wavelength conversions using four-wave mixing in semiconductor optical amplifiers

Wavelength conversion in wavelength-division multiplexed (WDM) communication systems would provide significant network performance improvement. Optoelectronic, cross-gain saturation, and cross phase saturation wavelength converters are candidate technologies that have been well characterized, however, they are not “transparent” to either bit-rate or modulation format. Complete transparency is offered only by ultrafast wave mixing techniques-in the present case four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs)

Polarization-independent wavelength conversion at 2.5 Gb/s by dual-pump four-wave mixing in a strained semiconductor optical amplifier

We give a general expression for the polarization dependence of the four-wave mixing (FWM) efficiency in the dual-pump configuration. This expression, along with some general properties of the FWM susceptibility tensor, is used to propose a simple scheme to generate a nearly (1.5-dB variation) polarization independent FWM converted signal. The viability of this scheme is verified in a wavelength conversion experiment at 2.5 Gb/s

Using tensor properties of four wave mixing in semiconductor optical amplifiers for polarization independent wavelength conversion or pump suppression

Summary form only given. Wavelength conversion by four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) has several advantages, including transparency to the modulation format and bit rate. An important feature of the intensity and polarization of the FWM wavelength-converted signal is their dependence on the polarizations of the input signal and pump waves. In this paper, we discuss the polarization properties of the FWM susceptibility χ_(ijkl) of strained multiple quantum well SOAs and their potential for application to polarization-independent wavelength conversion and pump suppression

Cross talk penalty in two-channel wavelength conversion by four-wave mixing in a strained semiconductor optical amplifier

A crucial function in wavelength-division multiplexed (WDM) all-optical networks is a wavelength converter. This function enhances wavelength routing options and improves network reconfigurability. Here we present a systematic study of the cross talk penalty as a function of the pump-to-signal power ratio for two 2.5-Gbit/s ASK channels separated by 1.5 nm

Measurement of the interwell carrier transport lifetime in multiquantum-well optical amplifiers by polarization-resolved four-wave mixing

Polarization-resolved four-wave mixing spectroscopy is used to study interwell carrier dynamics in an alternating-strain multiquantum-well optical amplifier. The experimental data are found to be in good agreement with a simple model based on quantum capture/escape and diffusion processes. The results suggest that the interwell transport in this structure is mainly limited by carrier escape, and give an estimate of 16 ps for the overall transport lifetime

Polarization Properties of Four-Wave Mixing in Strained Semiconductor Optical Amplifiers

Abstruct- We present a theoretical and experimental study of the polarization properties of the four-wave mixing susceptibility of highly-strained multiquantum-well optical amplifiers and show how the intensity and polarization of the four-wave mixing signal depend on the polarization of the input waves. We demonstrate the validity of our model by generating a wavelength-converted signal having a polarization orthogonal to that of the pump wave at the output of the amplifier. In addition, we discuss the possibility of making the conversion efficiency independent of the input signal polarization by proper selection of the pump polarization. OUR-WAVE MIXING (FWM) in semiconductor optical F amplifiers (SOA's) [ll-[4] is a promising candidate for the implementation of wavelength conversion [3], [5], [6] in future high-speed multichannel lightwave networks. In a typical FWM wavelength conversion device, beating of the input signal with a strong pump wave produces dynamic gain and index gratings through modulation of carrier density (CDM), and through intraband processes such as carrier heating (CH) and spectral hole burning (SHB). The wavelength converted signal is then generated by scattering of the pump wave from these gratings. In this Letter, we present a simple model explaining the polarization dependence of the FWM susceptibility in highlystrained multiquantum-well SOA's. An important prediction, which is also verified experimentally, is that the conversion efficiency of such devices remains finite even for orthogonallypolarized pump and input signals. We verify our model by showing how it is possible to control the polarization of the wavelength-converted signal. Finally, we discuss the feasibility of making the FWM conversion efficiency independent of the input signal polarization. Several density matrix calculations of the FWM susceptibility of SOA's (for the case of copolarized waves) are available in the literature [1], [4]. Here, we allow for arbitrary polarizations (which requires explicit inclusion in the equations o