This paper proposes a novel 4×4 free-space bi-directional fiber optical switch. The switch is independent of the optical polarization, which can lead to polarization-dependent loss. When the input light beam incident on the polarization beam splitters (PBS) coating satisfies Brewster Condition, it is decomposed into two orthogonal linear polarized lights: P-polarized light and S-polarized light. In the paper, the free-space optical switches elements include a polarization control unit and a routing unit, and the former will be discussed emphatically. The polarization control unit can be acted by Ferroelectric Liquid Crystal (FLC) or half-wave plate array. By comparing the two methods, half-wave plate array will be chosen in the experiment. The controlling circuit of driving half-wave plate array is designed and polarization-dependent loss (PDL) in 4×4 optical switch using half-wave plate array is analyzed. The experiment results indicate that the insertion loss is less than 4.4 dB, the interchannel crosstalk is about 32 dB and the switching time of the optical switch is about 2 ms.
In order to find the optimal design for a given specification of an optical communication link, an integrated simulation of electronic, optoelectronic, and optical components of a complete system is required. It is very important to be able to simulate at both system level and detailed model level. This kind of model is feasible due to the high potential of Verilog-AMS language. In this paper, we propose an effective top-down design methodology and employ it in the development of a complete VCSEL-based optical links simulation. The principle of top-down methodology is that the development would proceed from the system to device level. To design a hierarchical model for VCSEL based optical links, the design framework is organized in three levels of hierarchy. The models are developed, and implemented in Verilog-AMS. Therefore, the model parameters are fitted to measured data. A sample transient simulation demonstrates the functioning of our implementation. Suggestions for future directions in top-down methodology used for optoelectronic systems technology are also presented.