Modeling and fabrication of rare-earth-doped integrated optical waveguide amplifiers

This thesis addresses modeling and fabrication issues related to erbium/ytterbium-doped glass waveguide amplifiers. Compact optical waveguides which amplify light in the 1.55 {dollar}mu{dollar}m wavelength window will play an important role in complementing other integrated optic devices such as modulators and switches. In designing waveguide amplifiers, two features are of utmost importance: (1) high signal gain over short distances. (2) compatibility for integration with other devices. The requirement for gain over a short distance necessitates the use of rare-earth dopant levels two orders of magnitude higher than currently employed in fiber amplifiers.; A numerical model to simulate the gain and noise characteristics of waveguide amplifiers doped heavily with rare-earth ions is described. Deleterious effects associated with high doping, such as ion-ion interaction, are included in the model. The model is validated by comparing simulation results with experimental and numerical results found in the literature. Based on modeling results, an attempt was made to fabricate compact ridge waveguides from thin films of sputter-deposited erbium-doped glass. In response to various spectroscopic and micromachining impediments encountered with this process, alternative waveguide configurations were explored. The design and fabrication of strip-loaded waveguides using two dielectric glass films in conjunction is discussed. In this configuration, micromachining impediments inherent to the active glass film can be circumvented. Experimental and simulation results for this device are shown to be in close agreement. Improvements are forecast by the model.; Optical waveguides were also formed directly on rare-earth-doped bulk glasses. In one approach, a passive polymer waveguide was dispensed on top of a bulk glass. The evanescent field of light propagating in the polymer layer was seen to penetrate the bulk substrate and interact with rare-earth ions. Experimental and simulation results associated with this novel approach are discussed. Finally, an Er/Yb-doped optical waveguide amplifier yielding 3.5 dB of net signal gain over 4.2 cm with 120 mW of pump power is demonstrated. This singlemode device was formed on a bulk glass using a field-assisted, silver-sodium ion-exchange process.