Abstract

An optical setup was devised for the Electrical engineering undergraduate course “Photonic devices” where students were introduced to a simple visible diode laser based method of measuring the refractive indices of liquid samples in a transparent quartz cuvette placed on a computer-controlled rotating stage. When setting the cuvette at a small angle with respect to the incident laser beam, the light transmission through the cuvette results in a small mm-scale deflection of the laser path. The evaluation of the sample’s refractive index hinges on measuring the beam displacement. Moreover, by positioning the cuvette at normal incidence and recording the optical power after passing through various liquid samples (e.g. distilled water, maple syrup) and comparing with a reference (empty cuvette), students learn to estimate the attenuation coefficients of the substances by taking into account the contribution of the multiple Fresnel reflections. Finally, the same optical setup is also used by students to perform the “knife-edge” technique for the characterization of the beam profile emitted by the visible diode laser used in the setup. The proposed setup was implemented in the fall 2018 where undergraduate students were able to practice optical alignment and implement the concepts of material refractive indices and attenuation, as well as revisit the Gaussian beam theory taught in-class.

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