  Photonic Integrated Circuits (PIC) are best known for their important role in
the telecommunication sector, e.g. high speed communication devices in data
centers. However, PIC also hold the promise for innovation in sectors like life
science, medicine, sensing, automotive etc. The past two decades have seen
efforts of utilizing PIC to enhance the performance of instrumentation for
astronomical telescopes, perhaps the most spectacular example being the
integrated optics beam combiner for the interferometer GRAVITY at the ESO Very
Large Telescope. This instrument has enabled observations of the supermassive
black hole in the center of the Milky Way at unprecedented angular resolution,
eventually leading to the Nobel Price for Physics in 2020. Several groups
worldwide are actively engaged in the emerging field of astrophotonics
research, amongst them the innoFSPEC Center in Potsdam, Germany. We present
results for a number of applications developed at innoFSPEC, notably PIC for
integrated photonic spectrographs on the basis of arrayed waveguide gratings
and the PAWS demonstrator (Potsdam Arrayed Waveguide Spectrograph), PIC-based
ring resonators in astronomical frequency combs for precision wavelength
calibration, discrete beam combiners (DBC) for large astronomical
interferometers, as well as aperiodic fiber Bragg gratings for complex
astronomical filters and their possible derivatives in PIC.
