1 Valovna dolžina (nm)

Band structure: direct vs. indirect Eg 2

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Dr. Mike Nofziger 2010 “LASERS” ….. Example: CD Diode Lasers output in the near- infrared ≈ 5 – 50mW output actual laser chip from a CD player

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16 VCSELs high performance and low cost advantages. 1. The structure can be integrated in two-dimensional array configuration. 2. Low threshold currents enable high-density arrays. 3. Surface-normal emission and nearly identical to the photo detector geometry -> easy alignment and packaging. 4. Circular and low divergence output beams eliminate the need for corrective optics.

17 5. Passive versus active fiber alignment, combined with high fiber-coupling efficiency. 6. Low-cost potential because the devices are completed and tested at the wafer level. 7. Lower temperature-sensitivity compared to edge-emitting laser diodes. 8. High transmission speed with low power consumption.

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Dr. Mike Nofziger 2010 “LASERS” ….. Example: High-Power Diodes - Stacks of linear arrays of diode lasers - 100’s to kilowatts of power - near infrared wavelengths - used for materials processing

Kvantna kaskada – zaporedje prehodov med kvantnimi jamami

24 Band diagramLayer sequence Emission spectrum at room temperature Light- and Volt-current characteristics

Laser na proste elektrone

The European x-ray free electron laser (European XFEL) an X-ray research laser facility currently under construction planned to be operational by the end of participating countries (Denmark, France, Germany, Greece, Hungary, Italy, Poland, Russia, Slovakia, Spain, Sweden and Switzerland) Electrons will be accelerated to an energy of up to 17.5 GeV by a 2.1 km long superconducting linear accelerator. Total length 3.4 km.superconductinglinear accelerator Wavelength 0.05 to 6 nm