Multiple signal representation simulation of photonic devices,systems, and networks

Photonic systems design requires simulation over a wide range of scales; from wavelength-sized resonances in lasers and filters, to interactions in global networks. To design these global systems, while considering the effects of the smallest component, requires sophisticated simulation technology. We have developed the Photonic Transmission Design Suite, which includes five different signal representations, so that the details of device performance can be efficiently considered within a large network simulation. Alternatively, a design can be studied using a coarse signal representation before switching to a detailed representation for further refinement. We give examples of the application of these representations, and show how the representation of a signal is adapted as it propagates through a system to optimize simulation efficiency     

Noise analysis of frequency converters utilizingsemiconductor-laser amplifiers

This paper deals with a general problem concerning semiconductor-laser amplifiers used for frequency conversion. The amplified spontaneous emission (ASE) of a saturated amplifier is investigated experimentally and theoretically. An analytical solution accounting for the spatial dependence of the inversion parameter as well as the spectral dependence of the ASE is derived. Hence, the results can be applied to arbitrary saturation conditions and frequency shifts. Our theory is applied to frequency converters based on four-wave mixing and is found to be in good agreement with both the numerical results and the experimental data. In order to quantify the performance of a frequency converter, a noise figure is defined and shown to be strongly dependent on the frequency detuning and the power of the input waves     

Gain dispersion and saturation effects in four-wave mixing insemiconductor laser amplifiers

This paper addresses four-wave mixing (FWM) in semiconductor laser amplifiers from the point of view of a propagation problem. The gain dispersion effect, i.e., the difference of the gain factors for the pump, probe and signal waves is shown to be significant in the case of large detunings >1 THz. It is given an analytical solution of the FWM problem including gain dispersion and saturation effects. Considering the saturation behaviour, it is shown that the linear gain factors for the different waves and the nonlinear susceptibilities associated with the different nonlinear effects must be characterized by different carrier densities at transparency. A comparison of our theory with a numerical model, with previous approaches and with experimental data is given     

Four-wave mixing in semiconductor optical amplifiers for frequencyconversion and fast optical switching

Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is an important tool for frequency conversion and fast optical switching in all-optical communication networks. We review the main applications of SOAs as nonlinear optical components. Concentrating on FWM, we define general parameters that are of relevance for signal processing applications. We show, how basic experiments and general simulation procedures can be used to determine optimum operating conditions for the intended applications. Besides a comprehensive investigation of FWM among continuous waves, we present new experimental results on FWM with picosecond optical pulses. A comparison of both reveals a different behavior and demonstrates that new optimization criteria and advanced theoretical models have to be applied for the case of short optical pulses. Moreover, we discuss the possibility to extract the dynamical SOA parameters from our experiments