Broadband mid-IR fiber optics for heterodyne spectroscopy in solar system exploration missions

We demonstrate a new design hollow optical fiber suitable for use on IR heterodyne spectroscopy in mid-infrared wavelength region. The spectral feature of the laser emission line and the system noise temperature obtained by heterodyne detection with hollow optical fiber is confirmed by a laboratory measurement. The system noise temperature less than 3000 K obtained by the experimental setup with the CO2 laser-based heterodyne system led by a hollow optical fiber is only ~100 % above the quantum limit. The hollow optical fiber allows heterodyne detection with a sufficient efficiency. This permits simplified fabrication, provides even more weight reduction. Further investigation is required for use of hollow optical fiber on the target source.