Abstract
A detailed investigation of the photo-inscription of waveguides in barium gallo-germanate (BGG, BaO, GeO2, Ga2O3) glass is presented. Upon irradiation of BGG glass samples of different contents of germanium dioxide with a femtosecond laser pulse train, positive refractive index changes are produced over a wide range of exposure conditions. Waveguides with a controllable diameter ranging from 4 to 35 µm and a maximum index change up to 10−2 were inscribed. A glass sample with custom molecular composition was purified to remove hydroxyl ions and reduce the strong absorption band near 3 µm. A careful tailoring of the writing conditions allowed for the inscription of low-loss waveguides supporting only two transverse modes at the wavelength of 2.78 µm. An upper bound for the propagation losses of 0.5 ± 0.1 dB/cm was determined, showing the great potential of the BGG glass family for the fabrication of core waveguides operating in the 2-4 µm spectral range. Our results actually open a pathway towards the integration of mid-IR photonic devices based on the BGG glass family.
Highlights
Over the last two decades, femtosecond laser direct inscription evolved into a compelling tool for the fabrication of tridimensional photonic devices embedded in optical materials
To assess the response of Barium GalloGermanate (BGG) glass to fs pulses over a wide range of exposure conditions, translation speed was varied over four orders of magnitude (0.05 to 50 mm·s−1) and pulse energy from the minimum measurable output power of the laser up to the maximum available
Effect of germanium oxide content on the photosensitivity BGG glass we studied the influence of the relative content of germanium oxide on BGG glass response to irradiation with femtosecond pulses
Summary
Over the last two decades, femtosecond laser direct inscription evolved into a compelling tool for the fabrication of tridimensional photonic devices embedded in optical materials. Among the other potential optical materials, heavy metal oxide (HMO) glasses represent attractive hosts for mid-IR photonic devices as they are mechanically resistant, chemically stable and exhibit an extended transmission in the infrared spectra up to 7-8 μm. A halogen component was introduced during the fabrication of a BGG sample with a custom composition (17.5 BaO, 65 GeO2, 17.5 Ga2O3) to eliminate bound hydroxyl in the glass matrix and suppress the strong absorption band between λ = 2.8 and 3.2 μm. Using this sample, we succeeded in inscribing low-loss core waveguides operating at a wavelength of λ = 2.785 μm. Our results clearly demonstrate the potential of BGG glasses as hosts for photo-induced integrated mid-IR photonic devices
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
