The scattering patterns observed have applications to the testing of optical fibers as well as to the understanding of natural optical phenomena. The experiment illustrates diffraction effects and also the geometric optics of skew rays through a tilted fiber. Students characterize a 5W diode laser bar. The power versus current curve is measured in addition to the spatial and spectral characteristics of the laser bar. Aspheric optics are used to couple the diode laser light into a solid laser crystal.
Optimum coupling is studied.
The laser is aligned and its characteristics are analyzed for power, spatial profile and spectral quality. The temporal pulses are observed with a fast photodiode and an oscilloscope in the nanosecond regime and with a commercial picosecond autocorrelator. Mode locking is achieved passively with either intracavity second-harmonic generation or a semiconductor saturable absorber. Reflections from discontinuities, such as fiber alignment mismatches, are studied both in the time domain and, using spectral analysis, in the frequency domain. Integrated optical structures are studied and students investigate the behavior of different substrates and fiber materials with respect to system performance.