Efficient Coupling with One GaP Lens of Tapered Semiconductor Laser Into Single-Mode Fiber

Tapered semiconductor lasers have demonstrated output powers up to 4 W in a near-diffraction-limited beam. The output beam has a very high aspect ratio and astigmatism, making it very difficult to couple into a single-mode fiber. We propose to develop a single anamorphic microlens to efficiently correct the beam aberrations and directly focus it into a single-mode fiber. The mass-transport technique will be used to fabricate the microlens in the high refractive index GaP material. The lens profile will be analytically calculated using optical path length considerations, and will be digitally encoded in the substrate using photolithography and etching processes prior to mass-transport. The microlens will be directly mounted with the tapered laser on a heat sink for a compact and rugged package, and its output as well the coupling efficiency into a single-mode fiber will be fully characterized. This technology uses integrated circuit techniques and is directly amenable to mass production. A compact, rugged package will be designed for the laser-lens-fiber assembly. A prototype will be made. Alignment tolerances will be calculated and experimentally measured. Design guidelines will be defined for a 1 W device.| Benefits: The development of a high power, single-mode fiber coupled device will open and expand the mass market of telecommunications and other industrial applications. The mass market will lead to a large reduction in price of high power semiconductor lasers. Other applications include space telecommunications, medical lasers and industrial welders.|