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How to run a semiconductor diode laser in a stable way
Umeå University, Faculty of Science and Technology, Department of Physics.
2012 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Interferometry and holography are two well-known methods for measuring distances, positions, vibrations, index of refraction etc. In these methods a coherent light source is used to create interference between different parts of the light. Since the wavelength of the light is used as reference it is possible to achieve very good accuracy in the measurements. The need of small and cheap light sources for these applications is large and an interesting alternative would be to use ordinary semiconductor diode lasers. These are unfortunately not designed to give sufficiently good coherence. In this Master Thesis work investigations of how the coherence of semiconductor diode lasers is affected by changes in temperature, injection current and between different individuals are performed. A Michelson interferometer is used to create an interference pattern where the contrast then can be analyzed. The contrast is related to the coherence of the laser, i.e., good coherence will give high contrast. The results show that in order to drive the laser in a stable way it is better to hold the temperature constant and varying the injection current until the wanted output power is achieved instead of doing the opposite. The results also indicate that the best coherence is achieved for low temperatures (around 10

OC) and high injection currents (around 80 mA). During these conditions a contrast of 70 % -80 % is achieved. The result of this Master Thesis work gives a hint on how to run a semiconductor diode laser in a stable way.

Place, publisher, year, edition, pages
Keyword [en]
diode laser, contrast, coherence
National Category
Atom and Molecular Physics and Optics
URN: urn:nbn:se:umu:diva-56794OAI: diva2:537583
External cooperation
Adopticum - Center for industrial optics
Subject / course
Examensarbete i teknisk fysik
Educational program
Master of Science Programme in Engineering Physics
Physics, Chemistry, Mathematics
Available from: 2012-07-27 Created: 2012-06-27 Last updated: 2012-07-27Bibliographically approved

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Atom and Molecular Physics and Optics

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