ECE-1466 Modern Optics Course Notes Part 10 Prof. Charles A. DiMarzio Northeastern University Spring 2002 May 02002 Chuck DiMarzio, Northeastern University

Chuck DiMarzio, Northeastern University Lecture Overview Two-Photon Mathematical Analysis Classical “Electron on a Spring” Non-Linear Response Quantum Second-Order Perturbation “Virtual State” Spatial and Temporal Issues May 02002 Chuck DiMarzio, Northeastern University

Classical Description (Electron as a Mass on a Spring) a x v v x May 02002 Chuck DiMarzio, Northeastern University

Chuck DiMarzio, Northeastern University Energy Level Diagrams Fluorescence 2-photon May 02002 Chuck DiMarzio, Northeastern University

Chuck DiMarzio, Northeastern University Mathematical Model Oversimplification, but useful for understanding Poisson Distribution Mean Number Probability of a Pair Time Interval Virtual State Lifetime May 02002 Chuck DiMarzio, Northeastern University

Chuck DiMarzio, Northeastern University Calculations Mean Number of Fluorescence Photons Mean Rate Defines d = 2-Photon cross-section in m4sec Typical Value For 1/10 Photon per 100fs (laser pulse interval) May 02002 Chuck DiMarzio, Northeastern University

Chuck DiMarzio, Northeastern University Power Requirement Photon Irradiance Irradance Diffraction-Limited Area (1 square micrometer) Average Power at 100MHz, 100 fs width May 02002 Chuck DiMarzio, Northeastern University

Spatial and Temporal Issues Focus the Light High Irradiance Depth-Slicing Resolution Sharpening Make the Pulse Short Low Duty Cycle Less Damage High Peak Power Stronger Signals E2 E E2A P=EA May 02002 Chuck DiMarzio, Northeastern University

Chuck DiMarzio, Northeastern University Course Summary Radiometry Diffraction F F’ Object Image Polarization Geometric Optics NL Optics Interference Applications May 02002 Chuck DiMarzio, Northeastern University