Fabrication and Characterization of Integrated Waveguide Laser Devices

University Of California-Davis, Davis CA

Investigators

Abstract

The overall objective of our proposal is to explore the fabrication and characterization of all-waveguide laser devices that integrate a lasing medium with optically written Bragg gratings and a nonlinear optical element in a single phosphate glass waveguide. The nonlinear element can either be a periodically poled (for frequency doubling) or uniformly poled segment (for an electro-optic modulator) of the waveguide device. The rapid growth of the telecommunications industry has led to intensive research and development of new fiber based components, such as Erbium doped fiber amplifiers (EDFAs), fiber Bragg gratings and fiber lasers. As a spin-off from telecom applications, fibers are now also rapidly finding their way into other industrial applications, such as medicine and sensor technology. For certain applications, waveguide structures may be preferred over fibers because of their compactness and the ability to integrate different optical components such as splitters, couplers and laser amplifiers or signal sources on a single substrate. Existing waveguide laser technology would be greatly enhanced if it could be integrated with a nonlinear optical, (2) , element in such a way that the laser and the nonlinear optical function were fabricated in the same waveguide. Such an integrated optics approach requires the use of Bragg gratings in the waveguide to define the laser cavity. Second-order optical nonlinearities, which do normally not occur in glasses, can be introduced through a thermal poling process. The research described here addresses the following two issues: 1. A study of the formation of refractive index changes and Bragg gratings through an optical writing process in phosphate glasses and waveguides. Here the goal is to effectively write Bragg gratings in phosphate glasses and waveguides using sensitization of the glass through doping or by writing the grating with ultra-short (100 fs) pulses from a high peak-power laser. 2. A study of the formation of a second-order nonlinearity through thermal poling in these glasses. Experiments will be carried out to determine whether a second-order nonlinearity can be induced in phosphate glasses and for which poling parameters and glass compositions it is optimized. This technology will lead to new integrated optical devices with applications in telecommunications - in particular WDM (wavelength division multiplexing)- and optical computing, as well as metrology, spectroscopy, and remote sensing. In addition, these studies will contribute to the understanding of photosensitivity and poling in glasses. Because of its multidisciplinary nature and great relevance for the high-tech industry, this research offers a unique opportunity for education and training of graduate students.