Fabrication of Bragg gratings in sub-wavelength diameter As2Se3 chalcogenide wires

The inscription of Bragg gratings in chalcogenide (As2Se3) wires with sub-wavelength diameter is proposed and demonstrated. A modified transverse holographic method employing He Ne laser light at a wavelength of {\lambda}w = 633 nm allows the writing of Bragg grating reflectors in the 1550 nm band. The gratings reach an extinction ratio of 40 dB in transmission and a negative photo-induced index change of \delta n~0.01. The inscription of Bragg gratings in chalcogenide microwires will enable the fabrication of new devices with applications in nonlinear optics, and sensing in the near-to-mid-infrared region of wavelengths.