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The oscillation wavelength shift of a semiconductor laser in a magnetic field has been known since the early 60's. However, this research has only been made at very low temperatures and in a very strong magnetic field. The observed wavelength shift was toward a short wavelength side, which was well accounted for in terms of the Landau level. The wavelength shift in a relatively weak magnetic field at room temperature by using recently developed Fabry-Perot type laser diodes has been reported recently. The observed wavelength shift was toward a long wavelength side in certain types of laser diodes in a certain magnetic field direction. The shift mechanism, however, has not been confirmed yet. Therefore, the wavelength shift and the output laser power change in a magnetic field are measured precisely in this work. The longer wavelength side shift and the output laser power decrease occur simultaneously in a certain magnetic field direction. Since these changes observed in this work correspond to the changes observed in increasing temperature, it is assumed that the magnetic field increases temperature around the active layer of the semiconductor laser.

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We have measured the oscillation characteristic shifts of laser diodes originated from a magnetic field. We observed wavelength shifts toward the longer wavelength side, i.e., a red shift, by using the beat note between test and reference lasers at room temperature in more than five different laser types, whereas the experiments in early 60's showed a blue shift at extremely low temperature and in a very strong magnetic field. We also observed output power shifts toward the lower power side. Both characteristic shifts showed the same tendencies at increased temperature. So, we considered the magnetic field increases the temperature of the laser diodes and then two characteristics will change. Our experiment, however, showed that the amounts of changes in temperature, estimated from each characteristic shift, do not coincide with each other. At the first stage ofour experiment, we removed the packaging parts oflaser diodes because they are made of ferromagnetic materials. However, we recently observed the wavelength shifts using the laser diodes with the packaging parts. We are now expecting the changes of the current flow around the active region in the magnetic field can explain this discrepancy by using the correlation analysis between these two shifts.

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