James L. Hohman

High-density interconnects for two-dimensional VCSEL arrays suitable for mass scale production

Polymer waveguides provide cost effective interconnect solutions for high-volume applications required by the rapid growth in VCSEL array sizes and product demand. Multimode polymer waveguides 34-channels wide have been stacked in arrays 12-layers high with center-to-center waveguide spacing of 125 +/- 2 microns between layers and 90 +/- 2 microns within a layer. No measurable crosstalk between channels has been observed even when separation between multimode waveguides was reduced to a 4-micron gap. Flexible polymers provide an out-of-plane bend radius of less than 5 mm that simplifies VCSEL packaging requirements and volume. Transitioning the waveguide pitch within and between the polymer layers from 125 to 250 microns enables interface of high-density VCSEL arrays to standard fiber ribbons. Passive fiber pigtailing to 62.5/125 fibers was achieved with < 0.5 dB loss. Pigtailing can be avoided entirely by direct connectorization of the polymer waveguide arrays with industry standard MT connectors. Optical CrossLinks Guidelink polymer waveguide devices are made form sheets several hundred feet long. Waveguides are formed using contact photolithography that requires no costly spin- coating, wet chemistry, embossing, modeling or etching techniques required by other planar waveguide fabrication processes. All required processes are suitable for automation with high-yield while at the same time drastically reducing the infrastructure required to produce devices. Currently, the equivalent of 100 six-inch wafers of planar waveguides can be produced in less than 2 days without automated machinery.

Excimer laser micromachining for passive fiber coupling to polymeric waveguide devices

The precise control and high-resolution ablation capability inherent in excimer laser machining make it ideally suited for creating slots for passive alignment of optical fibers to planar channel waveguides as well as for direct waveguide-to-waveguide coupling. This paper describes KrF excimer laser generation of passive alignment coupling slots and the results achieved using this technique with Polyguid polymeric integrated optic system single and multimode waveguide coupling.