1 / 19

Quantum Well Lasers

Quantum Well Lasers. Christopher P. Heagney Jason Yoo. What exactly is a LASER? Three types of electron/photon interactions Background information Basic Physics of Lasing. Active Region Quantum Effects Quantum Cascade Lasers Threshold Current Calculations. Objectives. “LASER”. L ight

brady-logan
Download Presentation

Quantum Well Lasers

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. Quantum Well Lasers Christopher P. Heagney Jason Yoo

  2. What exactly is a LASER? Three types of electron/photon interactions Background information Basic Physics of Lasing Active Region Quantum Effects Quantum Cascade Lasers Threshold Current Calculations Objectives

  3. “LASER” Light Amplification by the Stimulated Emission of Radiation

  4. Electron/Photon Interactions • Absorption • Spontaneous Emission • Stimulated Emission

  5. Laser Animation

  6. History 1958 - Arthur L. Schalow and Charles H. Townes invent the laser and publish a paper title “Infared and Optical Masers” 1961 - First continuous operation of an optically pumped solid state laser 1963 - Quantum well laser first suggested by H.Kroemer from the U.S. and Kazrinov and Alferov from the Soviet Union. 1975 - First quantum well laser operation made by J.P. Van der Ziel, R, Dingle, R.C Miller, W. Wiegmann, and W.A. Nordland, Jr. 1977 - R.D. Dupuis, P.D. Dapkus, N. Holonyak submitted paper demonstrating first quantum well injection laser 1994 - Quantum cascade lasers first developed

  7. Main requirements for Lasing • Initial Photons • Population Inversion • Threshold Current

  8. Semiconductor Laser

  9. Interband Lasing Concept

  10. Intersubband Lasing Concept

  11. Гgth≡ mode gain required for lasing αi≡ internal mode loss Гoe(Г gth-αi)L*Гbe(Гgth-αi)L = I gth = (Г-1)[αi + (2L)-1* ln (RoRb)-1] Threshold Gain Concept

  12. Quantum Cascade Laser

  13. Spikes shown are the energy levels that correspond to tunneling phenomena. Illustrates Transmission Probability as Electron Energy increases. Clearly visible are the valence and conduction bands as well as a vivid drop in transmission through the energy gap.

  14. Quantized Electron and Hole States in a quantum box. • kx and ky are in-plave wave vectors

  15. Problem Jth(QC) = [e/21][dz/(Npz)][(m+I)/(in-1)] + [e/(in-1)BG exp(-/(kT))  = 2 + 1 + (21)/’21 21 = (2/42r2)(A21/v)

  16. Problem e = electron charge 21 = stimulated emission cross section dz = first active well width Np = number of cascade stages z = transverse optical confinement factor m = mirror loss i = internal mode loss in = injection efficiency into upper laser level 1 = lifetime of C1 state ’21 = total relaxation time between C2 and C1 BG = doping sheet density in the Bragg mirror  = thermal activation energy r = mode-refractive index A21 = Einstein’s coefficient for spontaneous emission from level E2 to E1

  17. Problem Assumptions dz = 4.5 nm Np = 25 cascade stages z = 2.1 x 10-3 m = 5.6 cm-1 i = 10 cm-1 1 = 0.6 ps 2 = 1.43 ps ’21 = 1.8 ps BG = 1.2 x 1011 cm-2 r = 3.22 Electron Injection Efficency = .8 And the answer is….

  18. The Answer: 1

More Related