Towards 3D-photonic, multi-telescope beam combiners for mid-infrared astrointerferometry

Area of Science:

• Astronomy
• Optical Engineering
• Photonics

Background:

• High-precision optical astronomical interferometry has advanced significantly due to photonic technologies over the past two decades.
• Near-infrared interferometric instruments currently utilize integrated optics (IO) to combine up to four telescopes, delivering high-resolution, hyperspectral images.

Purpose of the Study:

• To develop multi-telescope integrated optics (IO) beam combiners for mid-infrared interferometry.
• To extend interferometric capabilities beyond near-infrared bands and combine more telescopes simultaneously.

Main Methods:

• Exploiting three-dimensional (3D) structuring capabilities of ultrafast laser inscription.
• Developing and characterizing 2- and 4-telescope beam combiner prototypes.
• Utilizing Gallium Lanthanum Sulfide substrates and femtosecond laser writing.
• Testing beam combiners at a wavelength of 3.39 µm.

Main Results:

• Characterized the capability of 2- and 4-telescope beam combiners to retrieve visibility amplitude and phase.
• Prototypes demonstrated feasibility of multi-telescope combination in the mid-infrared.
• Numerical simulations indicated areas for performance improvement.

Conclusions:

• Ultrafast laser inscription is a viable technique for fabricating mid-infrared interferometric beam combiners.
• Further development is needed to optimize performance for future astronomical applications.
• The study provides a roadmap for advancing multi-telescope mid-infrared interferometry.