The thesis work 'DESIGN AND FABRICATION OF SUPERCONTINUUM SOURCE IN MEDIUM INFRARED WAVELENGTH RANGE FOR CHEMICAL / BIOLOGICAL MONITORING' describes the simulated and experimental results of the study conducted on two families of commercial fibers (NUFERN and IRFLEX) reused for the generation of the supercontinuous phenomenon at a wavelength of 2 um. The aim is to compare and evaluate which of them is the most promising for future applications in the field of chemical / biological monitoring. The fibers in question are active fibers: NUFERN UHNAs, characterized by a high numerical aperture, are composed of silica (SiO2) and a low concentration of germanium (Ge) in the core; the IRF-S from IRflex whose basic chemical composition is arsenic sulphide (As2S3). The lasers used as sources in the experimental set-ups are owned by the Laser Physics Group of the Norwegian University of Science and Technology (NTNU), where the research was conducted: a holmium picosecond laser and a mode-locked femtosecond laser in Chromium (Cr: ZnS)), operating respectively at the wavelength of 2090 nm and 2360 nm and with a repetition rate of 5.1 MHz and 143 MHz. The interest in focusing on these wavelengths is given by the lack of data collected in this range of work on commercial fibers. In addition, the simpler availability of these fibers, which can be purchased directly from direct producers, unlike those made ad hoc for specific studies, further fuels the need to investigate the subject. The focus of the project is the experimental session preceded by the modeling phase conducted with COMSOL Multiphysics, MATLAB and RP Fiber Power, useful for evaluating the optimal parameters to be used during the laboratory session, such as fiber length, pulse energy, types of focal lenses , etc. With both the laser sources and the families of fibers used it is possible to obtain promising results in the supercontinuous: by varying the pulse energy, in the case of the highest value tested, a good spectral broadening was appreciated both in the Germanate fibers (Δλ = 350 nm) and in chalcogenures (Δλ = 1000 nm). The comparison between the experimental and theoretical results made it possible to make a first improvement to the initial modeling codes, implemented in order to obtain results as close as possible to the measured values and to accurately estimate the future behavior of other commercial fibers in applications that exploit the phenomenon of supercontinuous.
Il lavoro di tesi ' DESIGN AND FABRICATION OF SUPERCONTINUUM SOURCE IN MEDIUM INFRARED WAVELENGTH RANGE FOR CHEMICAL/BIOLOGICAL MONITORING' descrive i risultati simulati e sperimentali dello studio condotto su due famiglie di fibre commerciali (NUFERN e IRFLEX) rimpiegate per la generazione del fenomeno del supercontinuo alla lunghezza d'onda di 2 um. L'obiettivo è quello di confrontare e valutare quale di esse sia la più promettente per applicazioni future nel campo del monitoraggio chimico/biologico. Le fibre in esame sono fibre attive: le UHNA della NUFERN, caratterizzate da un’elevata apertura numerica, sono composte da silice (SiO2) e da una bassa concentrazione di germanio (Ge) nel nucleo; le IRF-S della IRflex la cui composizione chimica di base è solfuro di arsenico (As2S3). I laser utilizzati come sorgenti nei set-up sperimentali sono di proprietà del Laser Physics Group dell'Università Norvegese di Scienza e Tecnologia (NTNU), dove sono state condotte le ricerche: un laser a picosecondi in Olmio ed un mode-locked laser a femtosecondo in Cromo (Cr:ZnS) ), operanti rispettivamente alla lunghezza d’onda di 2090 nm e 2360 nm e con un repetition rate di 5,1 MHz e 143 MHz. L’interesse nel concentrarsi su queste lunghezze d'onda è dato dalla mancanza di dati raccolti in questa gamma di lavoro su fibre commerciali. Inoltre, la più semplice reperibilità di queste fibre, direttamente acquistabili dai produttori diretti a differenza di quelle realizzate ad hoc per degli specifici studi, alimenta maggiormente la necessità di approfondire l’argomento. Fulcro del progetto è la sessione sperimentale preceduta dalla fase di modeling condotta con COMSOL Multiphysics, MATLAB e RP Fiber Power utile a valutare i parametri ottimali da impiegare durante la sessione di laboratorio, quali lunghezza delle fibre, energia dell’impulso, tipi di lenti focali, etc. Con entrambe le sorgenti laser e le famiglie di fibre impiegate è possibile ottenere promettenti risultati nel supercontinuo: variando l’energia dell’impulso, nel caso del valore più alto sperimentato, è stato apprezzato un buon allargamento spettrale sia nelle fibre germanate (Δλ = 350 nm) che nelle calcogenure (Δλ = 1000 nm). La comparazione tra i risultati sperimentali e quelli teorici ha permesso di apportare una prima miglioria ai codici di modeling iniziali, implementati al fine di ottenere risultati il più possibile vicini ai valori misurati e stimare con accuratezza il comportamento futuro di altre fibre commerciali in applicazioni che sfruttano il fenomeno del supercontinuo.
PROGETTAZIONE E FABBRICAZIONE DI UNA SORGENTE DI SUPERCONTINUO NEL RANGE DI LUNGHEZZE D'ONDA DEL MEDIO INFRAROSSO PER IL MONITORAGGIO CHIMICO / BIOLOGICO
CLEMENTE, CATERINA
2019/2020
Abstract
The thesis work 'DESIGN AND FABRICATION OF SUPERCONTINUUM SOURCE IN MEDIUM INFRARED WAVELENGTH RANGE FOR CHEMICAL / BIOLOGICAL MONITORING' describes the simulated and experimental results of the study conducted on two families of commercial fibers (NUFERN and IRFLEX) reused for the generation of the supercontinuous phenomenon at a wavelength of 2 um. The aim is to compare and evaluate which of them is the most promising for future applications in the field of chemical / biological monitoring. The fibers in question are active fibers: NUFERN UHNAs, characterized by a high numerical aperture, are composed of silica (SiO2) and a low concentration of germanium (Ge) in the core; the IRF-S from IRflex whose basic chemical composition is arsenic sulphide (As2S3). The lasers used as sources in the experimental set-ups are owned by the Laser Physics Group of the Norwegian University of Science and Technology (NTNU), where the research was conducted: a holmium picosecond laser and a mode-locked femtosecond laser in Chromium (Cr: ZnS)), operating respectively at the wavelength of 2090 nm and 2360 nm and with a repetition rate of 5.1 MHz and 143 MHz. The interest in focusing on these wavelengths is given by the lack of data collected in this range of work on commercial fibers. In addition, the simpler availability of these fibers, which can be purchased directly from direct producers, unlike those made ad hoc for specific studies, further fuels the need to investigate the subject. The focus of the project is the experimental session preceded by the modeling phase conducted with COMSOL Multiphysics, MATLAB and RP Fiber Power, useful for evaluating the optimal parameters to be used during the laboratory session, such as fiber length, pulse energy, types of focal lenses , etc. With both the laser sources and the families of fibers used it is possible to obtain promising results in the supercontinuous: by varying the pulse energy, in the case of the highest value tested, a good spectral broadening was appreciated both in the Germanate fibers (Δλ = 350 nm) and in chalcogenures (Δλ = 1000 nm). The comparison between the experimental and theoretical results made it possible to make a first improvement to the initial modeling codes, implemented in order to obtain results as close as possible to the measured values and to accurately estimate the future behavior of other commercial fibers in applications that exploit the phenomenon of supercontinuous.I documenti in UNITESI sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/20.500.14253/103496