Browsing by Subject "Supercontinuum generation"

Now showing 1 - 4 of 4

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
Development of multicore and tapered chalcogenide fibers for supercontinuum generation
(2016-12) Saleh, Abba Usman
The dramatic spectral broadening of an electromagnetic radiation as it propagates through a nonlinear medium is called Supercontinuum generation. Supercontinuum generation is indeed regarded as one of the prominent phenomenon in nonlinear optics and photonics with burgeoning applications in various fields such as spectroscopy, early cancer diagnostics, gas sensing, food quality control, uorescence microscopy e.t.c. Supercontinuum generation in optical fibers is however associated with three fundamental challenges: minimization of input power threshold, maximization of output power as well as output spectrum of a supercontinuum. Two unique fabrication approaches namely "Direct tapering" and "Multicore fibers" were proposed to address the aforementioned challenges. Chalcogenide nanowires were fabricated via direct tapering of chalcogenide glasses, and spectral broadening with extremely low peak power of 2 W was demonstrated. Multicore array of chalcogenide step index fibers were also fabricated using a new method. The fabricated step index fiber has a diameter 1.35 m which was engineered to have a zero dispersion wavelength (ZDW) around 1100 nm with a pump of center wavelength at 1550 nm .Using split step Fourier method, it was shown that the fiber possesses a great potential for severe spectral broadening. Supercontinuum generation with the as drawn fiber, encountered challenges as well as proposed solutions were demonstrated and discussed.
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
High power supercontinuum generation in graded-index multimode fibers
(Institute of Electrical and Electronics Engineers Inc., 2019) Teğin, Uğur; Ortaç, Bülend
Over the years, supercontinuum generation in fibers are studied extensively. Photonic crystal fiber technology detailed these studies by allowing the change of dispersion parameter. Nowadays, multimode fibers attracted huge attention by enabling spatiotemporal nonlinearities and multimodal interactions. Recently, with graded-index multimode fibers, researchers reported new nonlinear dynamics such as cascaded Raman scattering [1], spatiotemporal instability [2,3], self-beam cleaning [4], multimode solitons [5].