Investigation of Laser Diode Properties


Overall, our experiment was straight forward and quite successful. Our task at the onset was to reproduce the behavior of the diode laser as observed in literature specifications. We were able to observe mode hopping and from this data calculate a value for the laser cavity of 0.29 + -0.02 mm. Our data also showed the linear response of the wavelength to changes in temperature and current.

Our data for the changing power of the laser also matched the expected behavior. Lasing in all cases didn't begin until a current of around 40 mA was applied to the diode and from there, the power increased linearly as current increased.

The final portion of the experiment was successful in that we were able to observe the radiation emitted in the electron transition from the 5p1/2 to 5s state of rubidium. This transition occurred when 794.9 nm light was incident upon the rubidium.

Sources of Error

The sources of error in our experiment are confined mostly to the inability of making precise measurements with our instrumentation. For instance, the Wavemeter Jr. only gives 0.1 nm precision in making its measurements. Also, the conversion factor used in converting current to power from the photodiode is dependent upon temperature. The value we used of 0.55 A/w was extrapolated from a graph with only moderate precision. Nonetheless, our data shows quite well the relationships between the wavelength, power, current, and temperature of a diode laser.

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