The Large Interferometer for Exoplanets (LIFE) is a proposed space mission designed to suppress starlight and collect thermal-infrared spectra of Earth-like exoplanets. Its goal is to obtain spectra with sufficient signal-to-noise from around 30 terrestrial planets. Even if no biosignatures are detected, such data would place strong statistical limits on the abundance of life in the Universe.

A key challenge is splitting the infrared spectrum to maximize performance. Dividing into two wavelength bands improves sensitivity, but more divisions complicate the optics. Spatial filtering over the crucial 8–18.5 µm range is particularly difficult with conventional step-index waveguides. At these wavelengths, such waveguides suffer from (1) strong bend losses due to weak confinement, and (2) poor mode matching with telescope beams, leading to inefficient coupling.

Photonic crystal fibers (PCFs) offer a possible solution. They are fabricated by drawing a structured preform into fiber, but suitable mid-infrared materials are limited. Current state-of-the-art telluride fibers exhibit losses of 0.65 dB/cm at 16 µm and cannot yet reach 18.5 µm. Lithographically produced waveguides also show unacceptably high losses. Still, progress with selenide-based PCFs has demonstrated losses as low as 0.03 dB/cm between absorption bands, showing the promise of this approach.

Our project explores whether microstructured waveguides can be created directly in transparent mid-infrared crystals. Two methods are being investigated: (1) femtosecond laser micromachining, where small focused beams write smooth curved voids inside crystals like diamond or KBr, and (2) single-shot drilling using curved Bessel beams.

The project is a collaboration of the Research School of Physics and the Research School of Astronomy & Astrophysics

Suitable background includes:

• Knowledge or hands-on experience with lasers and optical setups (beam alignment, focusing, interferometry).
• Familiarity with laser safety procedures.
• Programming skills for modeling and data analysis (Python, MATLAB, COMSOL, Labview, G-code, or similar).
• Ability to analyse optical spectra and mode profiles.
• Interest in experimental photonics, astronomical instrumentation, or materials science.
• Teamwork and scientific communication skills (presenting results, writing short reports).