• Astrophotonics (AP)
  • Multi-Channel Spectroscopy (VKS)

Mode expansion theory and application
Mode expansion theory and application in step-index multimode fibres for astronomical spectroscopy
Hernandez, E.; Roth, M.M.; Petermann, Kl; Kelz, A.; Moralejo, B.; Madhav, K.
In astronomical spectroscopy, optical fibres are abundantly used for multiplexing and decoupling the spectrograph from the telescope to provide stability in a controlled environment. However, fibres are less than perfect optical components and introduce complex effects that diminish the overall throughput, efficiency, and stability of the instrument. We present a novel numerical field propagation model that emulates the effects of modal noise, scrambling, and focal ratio degradation with a rigorous treatment of wave optics. We demonstrate that the simulation of the near- and far-field output of a fiber, injected into a ray-tracing model of the spectrograph, allows to assess performance at the detector level.
Journal Article