Quantum Well Lasers Christopher P. Heagney Jason Yoo.
-
Upload
horace-bond -
Category
Documents
-
view
223 -
download
3
Transcript of Quantum Well Lasers Christopher P. Heagney Jason Yoo.
![Page 1: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/1.jpg)
Quantum Well Lasers
Christopher P. Heagney
Jason Yoo
![Page 2: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/2.jpg)
Objectives
• 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
![Page 3: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/3.jpg)
• “LASER” • Light
• Amplification by the
• Stimulated
• Emission of
• Radiation
![Page 4: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/4.jpg)
Electron/Photon Interactions
• Absorption• Spontaneous
Emission• Stimulated Emission
![Page 5: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/5.jpg)
Laser Animation
![Page 6: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/6.jpg)
History1958 - 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
![Page 7: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/7.jpg)
Main requirements for Lasing
• Initial Photons
• Population Inversion
• Threshold Current
![Page 8: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/8.jpg)
Semiconductor Laser
![Page 9: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/9.jpg)
Interband Lasing Concept
![Page 10: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/10.jpg)
Intersubband Lasing Concept
![Page 11: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/11.jpg)
Threshold Gain Concept
Гgth ≡ mode gain required for lasing
αi ≡ internal mode loss
Гoe(Г gth-αi)L * Гbe(Г gth-αi)L = I
gth = (Г-1)[αi + (2L)-1 * ln (RoRb)-1]
![Page 12: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/12.jpg)
Quantum Cascade Laser
![Page 13: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/13.jpg)
![Page 14: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/14.jpg)
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.
![Page 15: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/15.jpg)
• Quantized Electron and Hole States
in a quantum box.
• kx and ky are in-plave wave vectors
![Page 16: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/16.jpg)
ProblemJth(QC) = [e/21][dz/(Npz)][(m+I)/(in-1)] +
[e/(in-1)BG exp(-/(kT))
= 2 + 1 + (21)/’21
21 = (2/42r2)(A21/v)
![Page 17: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/17.jpg)
Probleme = 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
![Page 18: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/18.jpg)
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
Problem
And the answer is….
![Page 19: Quantum Well Lasers Christopher P. Heagney Jason Yoo.](https://reader036.fdocuments.in/reader036/viewer/2022062313/56649d0c5503460f949e0bdc/html5/thumbnails/19.jpg)
The Answer:
1