Mid-infrared optical properties of integrated Pr3+-doped chalcogenides ridge waveguides
Abstract
The mid-infrared (mid-IR) spectral region is of great interest to many areas of science and technology as it contains two important transparency windows (3–5 μm and 8–13 μm) of the Earth’s atmosphere and strong characteristic vibrational transitions displayed by a large number of molecules. Praseodymium ions (Pr3+) feature characteristic transitions in the mid-IR and transmission range of chalcogenides based materials spans a large part of the mid-IR. The combination of efficient waveguiding properties with mid-IR light emitters would therefore be a key enabler of the development of mid-IR sensors-on-a-chip for health, security and environmental applications.
RF magnetron sputtering is used to deposit a Pr3+-doped chalcogenides guiding layer based on the quaternary system composed of Ga, Ge, Sb and Se atoms on different cladding layers. The optical design of integrated ridge waveguides for single-mode propagation at mid-IR wavelengths is presented. Then, the fabrication process of these structures using photolithography and RIE/ICP dry etching is described.
Single-mode propagation of mid-IR laser light is observed in ridge structures by optical near field imaging. Furthermore, Pr3+ guided photoluminescence in the mid-IR around 2.5 µm and 4.5 µm is demonstrated at room temperature using co-propagating pumping around 1.55 µm and investigated as a function of films annealing.