1 / 25

ECE-1466 Modern Optics Course Notes Part 9

ECE-1466 Modern Optics Course Notes Part 9. Prof. Charles A. DiMarzio Northeastern University Spring 2002. Lecture Overview. Basics of CW Lasers Gain Feedback Pulsed Lasers MOPA Gain-Switched Q-Switched Mode-Locked. Some Material Properties. Emission. Absorption. Absorption.

lmoss
Download Presentation

ECE-1466 Modern Optics Course Notes Part 9

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ECE-1466Modern OpticsCourse NotesPart 9 Prof. Charles A. DiMarzio Northeastern University Spring 2002 Chuck DiMarzio, Northeastern University

  2. Lecture Overview • Basics of CW Lasers • Gain • Feedback • Pulsed Lasers • MOPA • Gain-Switched • Q-Switched • Mode-Locked Chuck DiMarzio, Northeastern University

  3. Some Material Properties Emission Absorption Absorption Stimulated Spontaneous Energy Emission Chuck DiMarzio, Northeastern University

  4. Materials Solid Insulating Materials Semiconductors Liquid eg. Dyes Gas Pump Mechanisms Electrical Discharge Electrical Current Light Flashlamp Laser Chemical Thermal Other Laser Gain Chuck DiMarzio, Northeastern University

  5. Rate Equations for 2 Levels Photons Populations Energy 3 2 Actual Rate Equations Include Other Levels as Well 1 0 Chuck DiMarzio, Northeastern University

  6. Typical Laser Materials 4-Level 3-Level Energy Energy 3 3 Fast Fast 2 2 Pump Laser Pump Laser 1 1 Fast 0 Chuck DiMarzio, Northeastern University

  7. 4-Level Steady State, No Lasing 4-Level Energy 3 2 Pump 1 0 Chuck DiMarzio, Northeastern University

  8. Gain vs. Pump 4-Level g 3-Level g R03 R13 Chuck DiMarzio, Northeastern University

  9. Feedback Gain Round Trip f Chuck DiMarzio, Northeastern University

  10. Threshold Gain Gain Round Trip f Amplitude Equation Chuck DiMarzio, Northeastern University

  11. Laser Frequency Gain Round Trip f Phase Equation Cavity Modes f Chuck DiMarzio, Northeastern University

  12. Steady State Gain Round Trip f Amplitude Equation Cavity Modes f Chuck DiMarzio, Northeastern University

  13. Gain Saturation Mechanism Energy • Laser Light Depletes Upper-State Population • Lower Level Has a Fast Decay Time • Laser Does Not Pump Upper Level • Populations End Nearly Equal 3 2 1 0 Chuck DiMarzio, Northeastern University

  14. Gain Saturation Modes Inhomogeneously Broadened Line Homogeneously Broadened Line f f Chuck DiMarzio, Northeastern University

  15. Master Oscillator & Power Amp Power Amplifier 30 dB? for kilowatts output Faraday Isolator Rejects Reflected Light Master Oscillator (CW Laser) Typically a few Watts Modulator Typically E/O With Pulsed Input Chuck DiMarzio, Northeastern University

  16. Gain Switched Laser Pump t Gain Power Chuck DiMarzio, Northeastern University

  17. Q-Switched Laser Pump t Gain Cavity Q Power Chuck DiMarzio, Northeastern University

  18. Mode-Locked Laser Gain Medium Modulator at f=FSR Gain f Cavity Modes f Chuck DiMarzio, Northeastern University

  19. Mode Locking Example “Laser” Frequency 10 GHz. (for illustration only) FSR = Modulation Frequency = 100 MHz. 11 Modes Sum Laser Modes Irradiance Chuck DiMarzio, Northeastern University

  20. Second Harmonic a (Electron as a Mass on a Spring) a x v v x Chuck DiMarzio, Northeastern University

  21. Energy Level Diagrams Fluorescence 2-photon Chuck DiMarzio, Northeastern University

  22. Helium Neon Gas; Elect. Discharge 633 nm Wavelength milliwatts CW Argon Ion Gas; Elect. Discharge 514, 488, and others Watts CW Nd:YAG Glass; Flashlamp or Laser Pumped 1064 nm Watts Average Carbon Dioxide Gas; Elect. Discharge Around 10.6 mm Watts to kWatts, either CW or pulsed Some Lasers (1) Chuck DiMarzio, Northeastern University

  23. Diode Elect. Current Low Voltage Red to NIR mW and up Pulsed, Modulated to GHz, and CW Small non-circular beam output Dyes Usually Pumped by Another Laser Typically Visible Wavelengths Usually Quite Widely Tunable (eg. Grating) nJ or more Limited Lifetime (often requires flow) Some Lasers (2) Chuck DiMarzio, Northeastern University

  24. Green “Laser” Pointer Battery Laser Diode Nd:YAG Laser Frequency Doubler 1064 nm 532 nm 780 nm Chuck DiMarzio, Northeastern University

  25. Titanium Sapphire Laser Power Laser Diode Nd:YAG Laser Frequency Doubler 1064 nm 532 nm 780 nm Titanium Sapphire Very Broad Band and Can Be Mode- Locked Red to NIR Chuck DiMarzio, Northeastern University

More Related