James Scott Sutherland

Extraordinary laser-induced swelling of oxide glasses

We describe a novel process of laser-assisted fabrication of surface structures on doped oxide glasses with heights reaching 10 - 13% of the glass thickness. This effect manifests itself as a swelling of the irradiated portion of the glass, which occurs in a wide range of glass compositions. The extent of such swelling depends on the glass base composition. Doping with Fe, Ti, Co, Ce, and other transition metals allows for adjusting the absorption of the glass and maximizing the feature size. In the case of bumps grown on borosilicate glasses, we observe reversible glass swelling and the bump height can increase or decrease depending on whether the consecutive laser pulse has higher or lower energy compared with the previous one. The hypothetical mechanism includes laser heating of glass, glass melting, and directional flow. We review several potential applications of such glass swelling.

Laser texturing of doped borosilicate glasses

We describe a novel process of laser-assisted fabrication of surface structures on doped oxide glasses with heights reaching 10 - 13% of the glass thickness. This effect manifests itself as a swelling of the irradiated portion of the glass, and occurs in a wide range of glass compositions. The extent of such swelling depends on the glass base composition. Doping with Fe, Ti, Co, Ce, and other transition metals allows for adjusting the absorption of the glass and maximizing the feature size. In the case of bumps grown on borosilicate glasses, we observe reversible glass swelling and the bump height can increase or decrease depending on whether the consecutive laser pulse has higher or lower energy compared with the previous one. To understand the hypothetical mechanism, which includes laser heating of glass, glass melting, and directional flow, we explored density, refractive index, fictive temperature, and phase separation dynamics.

Optimum selection of high performance mirror substrates for diamond finishing

Due to advances in manufacturing processes, the substrate options for high performance diamond machined mirrors are expanding. Fewer compromises have to be made to achieve the needed weight, stiffness and finish while maintaining reasonable costs. In addition to the traditional mirror materials like aluminum and beryllium, there are some less common materials that can now be included in the trade space that fill the cost and performance continuum between wrought aluminum and beryllium mirrors. Aluminum and beryllium, respectively, had been the low cost/fair performance and very high cost/very high performance bounds for substrate selection. These additional substrates provide multiple near net shape blank options and processes, mostly within these bounds, that can be considered in a mirror cost versus performance trade analysis. This paper will include a summary of some advances in manufacturing processes that provide more substrate options for diamond machined mirrors with some sample performance analysis and data. This is merged with the traditional substrate options to illustrate the now larger mirror substrate trade space. Some benchmark structural analysis is provided to back up a generic mirror design trade study.

Laser-formed bumps on glass for precision alignment of planar optical components

This paper describes hybrid assembly of a wavelength selective switch using laser-formed glass bumps. Recently, a process was developed for forming raised bumps on IR-absorbing glass substrates using a focused laser beam. Glass bumps with heights exceeding 90 μm have been formed with an accuracy of ~100 nm using multiple laser shots. Proper selection of materials permits the bump height to be raised or lowered via subsequent laser shots by adjusting laser power. Processes are described for precision alignment of planar AWG components to a pedestal-mounted planar SOA array by forming three glass laser bumps beneath the AWG components. While the iterative process of bump formation and component position assessment was performed manually, this work demonstrates that the process is predictable and well-suited for automation.