Wavelength converters are a novel class of photonic integrated circuits that is crucial for multiwavelength fiber-optic communication networks . Such converters switch the flow of information from one wavelength to another. We present here the simulation and analysis of an optoelectronic InP-based tunable wavelength converter (Fig. 14.1) that monolithically combines a preamplified receiver with a postamplified sampled-grating distributed Bragg reflector (SG-DBR) laser diode . We employ the commercial software PICS3D , which was modified for the purpose of this investigation. Our self-consistent physical model takes into account many-body gain and absorption in the quantum wells, carrier drift and diffusion, and optical waveguiding. The time-consuming calculation of many-body spectra is performed externally , based on the theory outlined in Chap. 1 and in . Tabulated spectra of gain, spontaneous emission, and index change are then imported into PICS3D. Performance limitations by saturation effects are the main target of this investigation. The next section outlines the device structure. Section 14.3 describes physical device models and material parameters, including their experimental calibration. The following Sect. 14.4 investigates each component of the wavelength converter by three-dimensional (3D) steady-state simulation. Timedomain simulations of a similar SG-DBR laser can be found in Chap. 6.