Abstract:
Mid-infrared supercontinuum generation (MISG) represents a captivating frontier in photonics, where the quest for unprecedented spectral breadth meets the demands of cutting-edge applications. By harnessing the exquisite interplay of nonlinear optical processes within specially engineered optical fibers, MISG transforms ultrashort pulses into radiant torrents of light spanning the elusive mid-infrared spectrum. This phenomenon unveils opportunities across diverse disciplines, from advanced spectroscopy and high-resolution imaging to laser surgery, defense applications and environmental sensing. Its expansive spectral coverage, stretching beyond conventional limitations, unlocks new vistas for exploring molecular fingerprints, unveiling hidden structures, and probing elusive phenomena with unparalleled precision and depth. Its realization has predominantly relied on silica fibers, demanding exceedingly high peak powers and extensive fiber lengths. Besides, silica fibers have limitations in transmitting light beyond the near-infrared region due to material absorption. This study explores the design and analysis of chalcogenide (As2S3) and zinc germanium diphosphide (ZnGeP2) based microstructured optical fibers (MOFs) for MISG addressing the challenges regarding light transmission window, material absorption, high peak power and longer fiber length. Through rigorous computational analysis, the optimal fiber parameters are identified to achieve enhanced spectral broadening with particular emphasis on coherence and stability. Over five octave spanning MISG has been demonstrated numerically in the proposed fiber by solving nonlinear Schrodinger equation using split step Fourier method at 2200 nm pump wavelength.
Again, pure quartic solitons (PQS) stand at the forefront of modern photonics, poised to revolutionize industries and expand the frontiers of scientific inquiry including applications in ultrafast soliton laser driven cataract surgery and precise manufacturing of tiny medical devices. This thesis work explores the ZnGeP2 fiber as a platform for PQS formation for the first time. The fiber is such tuned that it represents zero second and third order dispersion at 2375 nm wavelength. PQS is then generated through the dynamic balance between fourth order dispersion and Kerr nonlinearity. Finally, PQS based MISG has been obtained in the same fiber with high coherence for various noise profile. Overall, this thesis provides a comprehensive framework for the design and analysis of MOFs tailored for MISG and PQS formation. The insights gleaned from this research not only deepen our understanding but also pave the way for the development of compact, efficient, and versatile photonic devices for a myriad of applications spanning spectroscopy, telecommunications, and laser technology