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Title:Optical parametric amplification of optical imaging signals
Author(s):Sun, Yi
Director of Research:Boppart, Stephen A
Doctoral Committee Chair(s):Boppart, Stephen A
Doctoral Committee Member(s):Gao, Liang; Dragic, Peter; Popescu, Gabriel
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Optical imaging
Optical parametric amplification
Optical detection
Abstract:Optical imaging is an essential approach to study the characteristics of samples in different fields of study, particularly in biomedical research. Various imaging techniques like optical coherence tomography and nonlinear optical microscopy provide the structural and molecular contrasts of biomedical samples. The detection of these optical imaging signals require special techniques to preserve the signal integrity and block the background noise. In particular, the optical imaging signal coming from deep tissue or nonlinear optical processes is too weak for regular photodiode-based detectors to effectively collect. Various optical detection methods have been invented, such as interferometry in optical coherence tomography (OCT) and secondary electron emission in photomultiplier tubes (PMTs). However, interferometry has only been used in linear reflectance imaging signal detection, while the PMT is severely affected by the background light noise since the secondary electron emission indiscriminately amplifies all the photoelectrons. In this thesis work, I proposed and realized the use of the optical parametric amplification process to amplify the imaging signals. As a nonlinear optical process, the optical parametric amplification (OPA) process heavily relies on the light coherence, and this characteristic of OPA completely rules out the incoherent background room light. In addition, the theoretical detection limit of OPA reaches and even surpasses the quantum mechanical shot noise limit, and potentially performs better than PMTs. For the detection of the microscopic imaging signal under ambient room light, the OPA utilized in this study achieved a similar signal gain and detection limit compared to the results of PMTs under extremely dark conditions. This superior performance of OPA detection may potentially replace the predominantly used PMTs in microscopy imaging
Issue Date:2021-10-14
Rights Information:Copyright 2021 Yi Sun
Date Available in IDEALS:2022-04-29
Date Deposited:2021-12

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