DARWIN NULLING INTERFEROMETER BREADBOARD III - SYMMETRY REQUIREMENTS AND MODAL FILTERING

摘要

In a nulling interferometer, the requirements on uniformity of phase, amplitude, and state of polarisation among the interferometer arms are stringent and hardly to be met in practice. The application of modal Iters makes deep nulling possible as such lters may reduce the mismatch of interfering elds. We review the principle of modal ltering and discuss the achievable lter bandwidth and the e ect of coupling phase. We give an overview over waveguides suitable for modal Itering, including also lossy multi-mode waveguides.