| There is a true need today for a compact, inexpensive, reliable, and simple-to-use tunable laser for applications ranging from wavelength-division-multiplexed optical transmission to spectroscopy. The micromechanical tunable vertical cavity surface emitting laser (VCSEL) is a well suited candidate for these applications.; This thesis discusses the design, fabrication, performance, and analysis of a micromechanical wavelength tunable VCSEL with one mirror in the shape of a cantilever. Tuning is achieved electrostatically through the actuation of the cantilever by reverse-biasing a pn-junction. The wavelength-dependent properties of the tunable VCSEL are presented in examples and comparison studies. Across the tuning range, the modal gain confinement factor in the longitudinal direction can vary by at least a factor of three. In addition, the use of only one dielectric mirror in the tunable VCSEL structure is found to provide little advantage in enhancing the tuning range. Furthermore, this tuning range is limited by a one-third rule, which is explained in this thesis. Device fabrication details are given and summarized.; The first monolithic top-emitting tunable VCSEL demonstrates 20nm of continuous tuning with sub-milliamp threshold and peak powers in excess of 1mW across most of the tuning range. A record tuning range of 31.6nm is also achieved in another device. Active wavelength stability to within one nanometer is demonstrated over a change of 35°C. Due to the temperature-insensitivity of the refractive index of the air gap, the rate of wavelength change with temperature in a tunable VCSEL can be substantially smaller than that in a regular VCSEL.; Electromechanical and optical analyses on this tunable VCSEL are performed. Three electrostatic-tuning models and their results are shown. Inclusion of the fringing fields in the cantilever geometry is found to provide only a 4% correction to the results that neglect those field lines in the analysis. Optical modal analysis of the tunable VCSEL serves to address the cost for wavelength tunability. Moreover, diffraction and tilt losses inherent in our VCSELs are quantified. While diffraction loss dominates in a smaller VCSEL, tilt loss is the culprit in a larger device. Good agreement between our analyses and experimental data is achieved and presented. |
