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Semiconductor Laser Physics

Semiconductor Laser Physics. Wide-gap semiconductor. Narrow-gap semiconductor. Wide-gap semiconductor. E g2. E g1. z. Double Heterojunction. z. E g2. E g1. E g2. Conduction band edge. Valence band edge. Type II. Type I. E c. E c. E g2. E g1. E g2. E g1. E v. E v. Type III.

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Semiconductor Laser Physics

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  1. Semiconductor Laser Physics

  2. Wide-gapsemiconductor Narrow-gap semiconductor Wide-gap semiconductor Eg2 Eg1 z Double Heterojunction z Eg2 Eg1 Eg2 Conduction band edge Valence band edge

  3. Type II Type I Ec Ec Eg2 Eg1 Eg2 Eg1 Ev Ev Type III Ec Eg1 Ev Ec Eg2 Ev

  4. Evolution of the threshold current of the semiconductor lasers

  5. Basov: Nobel prize 1964 (with Prokhorov and Townes) Basov, Vul, Popov, Krokhin: 1957 first semiconductor laser proposal and development 1961 first injection laser proposal (also Dumke 1962)

  6. The Nobel Prize in Physics 2000 Zhores I. Alferov Herbert Kroemer "for developing semiconductor heterostructures used in high-speed- and opto-electronics"

  7. III-V semiconductor grown on Ge

  8. 55 nm Lattice-matched InGaAs/AlInAs

  9. Molecular Beam Epitaxy A. Cho, Bell Labs Needs UHV 10-11 Torr , high-purity elemental materials, right temperature

  10. Growth rate 1 m/hr or 1 atomic layer in 1 sec

  11. Reflection High-Energy Electron Diffraction (RHEED)

  12. Metal-Organic Chemical Vapor Deposition (MOCVD)

  13. Growth rate 2-4 m/hr

  14. Materials for semiconductor lasers

  15. GaAs/AlxGa1-xAs; GaxIn1-xAsyP1-y/AlxIn1-xAs on InP; InAs1-xSb/AlGa1-xSb on GaSb

  16. Visible-UV range

  17. Laser Diode

  18. Laser waveguides • Vertical confinement • Lateral confinement • Gain-guided • Index guided: ridges, ribs • Buried heterostructure lasers

  19. Ridge laser

  20. H-field of the TM00 mode at 8.85 mum In QCLs you can cut the ridge through the active region: strong guiding

  21. H-field of the TM02 mode at 8.85 mum

  22. Modes: longitudinal and transverse

  23. Buried heterostructure laser

  24. 2743 B ridge

  25. 3032 C device 250K

  26. DFB lasers

  27. Vertical Cavity Surface-Emitting Laser

  28. Edge-emitting laser VCSEL • Large distance between • cavity modes: • – single-mode laser • Circular beam shape • Low threshold and • power consumption • 2D laser arrays • Wafer-scale testing • Ultrafast modulation

  29. For long wavelength laser based on InGaAsP/InP: index contrast is too low, need too many layers, the device is too resistive as a result Current spreading, many transverse modes -> need confinement for current and for the EM field

  30. Oxidized aperture VCSEL

  31. Oxide aperture Huffaker et al. APL 1994 Problems: different thermal expansion coefficient, strain, bad control, non-planar technology

  32. Phase-shifting mesa Lu et al., APL2004

  33. Oxide aperture and phase-shifting mesa Ahn et al. APL 2005

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