Browsing by Subject "Chalcogenide glasses"

Now showing 1 - 3 of 3

Open Access
All-chalcogenide core-shell fibers for nonlinear applications
(2015-11) Türedi, Bekir
The extreme spectral broadening phenomenon called as Supercontinuum generation is considered as one of the most striking phenomenon in nonlinear optics. Due to their broad spectra and uniformly distributed power over the spectra supercontinuum sources have found wide range of applications in areas such as spectroscopy, frequency metrology, optical coherence tomography, microscopy and telecommunications. In this thesis, we propose a new method to fabricate multicore fibers made of chalcogenide glasses for the use of high power Supercontinuum generation. We designed and fabricated a new seven-core-structured fiber with chalcogenide core /chalcogenide cladding step-index fiber embedded in polymer matrix. After three successful iterative steps we fabricated seven-core chalcogenide glasses fiber which has diameter around 1.35 μm which is engineered to be approximately zero dispersion. The refractive indices of these two materials at 1550 nm are 2.73 and 2.61; as a result the NA is engineered to 0.8 at this wavelength. The step index structure of the fiber provides the very well-confinement of light to the core of the fibers. This enables the more interaction of light with the highly nonlinear part of the fiber and preserves light to be absorbed by the polymer jacket which has high absorbance at IR region. By using split step Fourier method we showed the potential of our fiber to generate supercontinuum covering from 1 μm to 3.5 μm.
Open Access
Generation of new frequencies in toroid microcavities
(IEEE, 2008) Akbulut, Duygu; Tülek, Abdullah; Bayındır, Mehmet
Microtoroid cavities with ultra high Q-factor have been fabricated using a combined process of photolithography and reflow technique for observing non-linear effects such as generation of new frequency components. For this purpose SiO2 material was used to form the toroidal cavity shape, and chalcogenide material of As2S3 maintaining very high nonlinear refractive index was thermally evaporated on top with varying thicknesses. Simulation results of the fabricated structure have exhibited new frequency components around the excitation window of 1520 nm produced by non-linear interactions.
Open Access
Tuning the resonances of high Q-factor whispering gallery mode resonators for optoelectronic applications
(2022-07) Hüseyinoğlu, Ersin
Optical resonators allow highly efficient light-matter interaction; therefore, they are promising tools for optoelectronics and photonics. Especially optical resonators with high Q-factors such as toroidal resonators can be instrumentalized to develop efficient light sources, modulators, converters, and sensitive detectors. They are already being used for photonics research; however, some significant obstacles hinder their mass utilization in the industry. One of those obstacles is the current limitations of the fabrication method used to produce toroidal resonators. Due to the method used to achieve surface tension-induced microresonators (STIM), their fabrication is time-consuming. A new approach was presented to mass-produce STIMs. Instead of a fixed position laser, a raster scan laser was used to reflow the microresonators with different geometry types to overcome the mass-fabrication limitations. As a result, high-Q-factor (10^6) toroidal resonators were fabricated. Reflowing of elliptical and racetrack resonators were also demonstrated. Another problem that hinders the utilization of toroidal resonators is their high susceptibility to any errors originating from the fabrication process. Any deviation from the designed parameters leads to resonators with different resonant modes. A method for post-production tuning resonant mode of chalcogenide coated resonator was demonstrated. By using a thin Ge2Sb2Te5 layer coated silica toroidal resonator, 0.01 nm and 0.02 nm permanent mode shifts were achieved from 5 nm thick coated and 10 nm thick coated resonators, respectively.