Optical parametric amplification of optical imaging signals

Sun, Yi

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https://hdl.handle.net/2142/113955 Copy

Description

Title

Optical parametric amplification of optical imaging signals

Author(s)

Sun, Yi

Issue Date

2021-10-14

Director of Research (if dissertation) or Advisor (if thesis)

Boppart, Stephen A

Doctoral Committee Chair(s)

Boppart, Stephen A

Committee Member(s)

• Gao, Liang
• Dragic, Peter
• Popescu, Gabriel

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(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

Graduation Semester

2021-12

Type of Resource

Thesis

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http://hdl.handle.net/2142/113955

Copyright and License Information

Copyright 2021 Yi Sun

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