This Small Business Innovation Research (SBIR) Phase I project aims to develop a novel technique for manufacturing digital planar holograms, which will result in the enhancement of the brightness and power density of high-power laser diodes. Preliminary results of coupling lasers with holograms demonstrated a suppression of lateral modes, which enhances brightness and, additionally, narrows and stabilizes the laser spectrum. The successful introduction of this technology in the laser marketplace depends on the ability to fabricate planar holograms at a low cost and a simplification of their integration with laser diodes. The objective of this project is to develop and launch the commercialization of holographic lasers with higher a brightness and power. Phase I will consist of exploring a novel nano-manufacturing technology for low-cost fabrication of planar holograms by imprinting planar holograms into sol-gel films. The research will explore the issue of correlating the imprint process parameters with the sol-gel material properties to replicate computer-generated holograms with high performance. Phase II will demonstrate the monolithic integration of imprinted planar holograms into commercial laser diodes.
The broader impact/commercial potential of this project is that the brightness and power density of current, high-power laser diodes can be increased, while retaining their compact size and low cost. Semiconductor diode lasers have achieved high output power, allowing them to transition from special scientific items into true industrial tools. There is a huge interest worldwide in major industrial applications of semiconductor lasers such as direct materials processing and pump sources for industrial solid-state lasers and optical fiber lasers. Development of laser diodes with higher performance is being pursued by all major laser manufacturers and will have direct applications in multi-billion dollar markets, such as material processing and the semiconductor industry. The proposed nanofabrication process will allow the low-cost fabrication of digital planar holograms and will simplify their future monolithic integration with commercial laser diodes. Competing solutions are much more expensive and less compact.
The objective of this NSF Phase I SBIR project was to demonstrate a novel nanomanufacturing technology for the low-cost fabrication of planar holograms to be used as a novel method to increase the power density of commercial laser diodes. Digital planar holograms are revolutionary nanophotonic structures, which provide the ability to control light and create on-demand photonic devices. The focus of the project was to demonstrate that planar holograms can be fabricated using nanoimprinting of inorganic materials, and that their optical characteristics are suitable for their purpose of enhancing the lasing properties of high-power laser diodes. During the project, we developed a novel imprint process combining top-down (nanoimprint lithography) and bottom-up (sol-gel chemistry) approaches in order to replicate nanostructures into inorganic and crack-free thin films. A new type of metal-organic precursor was identified as the best choice for high-quality imprinting and good optical properties. Nanopatterned films with a high refractive index and relatively low propagation losses were reported, and promise a new way to fabricate nanophotonic chips. A few iterations of planar holograms were designed, simulated, and fabricated to have a better understanding of the light transformation by the holograms. A novel approach was proposed to achieve a synchronization of all the phases of the individual filaments to enhance the power density of commercial laser diodes. Results of Phase I have been discussed with a world-leading manufacturer of high-power laser diodes; they confirmed their high interest in the monolithic integration of Hlaser with their products; the goal for the Phase II project has been outlined.