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Microphotonics-based frequency combs for habitable exoplanet detection

Periodic Reporting for period 1 - STARCHIP (Microphotonics-based frequency combs for habitable exoplanet detection)

Reporting period: 2020-05-01 to 2021-10-31

Based on integrated photonic microresonator technology, a novel type of laser frequency comb for astronomical spectrograph calibration is developed, potentially contributing to the challenging search for habitable exoplanets. Generally, laser frequency combs provide a large set of well-defined, narrow laser lines that are equally spaced in optical frequency. Such frequency comb sources are well established and key to optical precision measurements. However, for astronomy, the individual comb lines need to be widely separated in optical frequency in order to be resolvable by the astronomical spectrograph. This is challenging to achieve with conventional laser systems.

Developing novel types of scientific instrumentation is key to making discoveries and advancing our knowledge about the world. This included in particular the fascinating question on whether (and/or where) there are other habitable planets similar to Earth. At the same time, the technology developed in this project, although geared towards a fundamental research application, can directly be transferred to other areas of application that are more ‘down to earth’; these include optical spectroscopy for environmental monitoring or for medical diagnostics.

While widely spaced frequency combs (‘astrocombs’) are challenging to achieve in conventional laser systems, this is naturally the case in photonic microresonator-based sources. The aim of STARCHIP is to establish a new class of photonic-chip microresonator-based comb sources of broadband spectra of resolvable lines, potentially from visible to mid-infrared wavelengths, that can overcome key challenges in astrocomb generation.
Novel microresonator geometries have been designed and fabricated and currently undergo initial laboratory test.
We expect to have demonstrated novel microresonator comb generators that can provide widely spaced frequency comb lines in spectral regions that are currently not accessible by this technology. With astronomical spectrograph calibration as a challenging application, we will further have explored the potential of these novel light sources for high-precision optical metrology. These results and the generated insights will also be transferrable to other potential applications ranging from optical spectroscopy to optical channel generation for broadband optical communication.
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