Acrylate-based optical waveguides have been fabricated with optical loss of 0.5 dB/cm at 1300 nm by means of a new material system that ensures stable optical and mechanical properties over a wide temperature range. No increase in loss was measured after 500 h at temperatures up to 150 degrees C, and there was no significant increase in loss during short (<5 min) temperature excursions to 300 degrees C for bonding. Single-mode waveguides were fabricated with refractive indices for core and clad of 1.505 and 1.500, respectively, so that the mode field is very similar to that of single-mode silica fiber. Guides were fabricated on both planar and structured substrates of Si and GaAs as well as on substrates coated with metals and dielectrics. Fabrication involved spin coating and UV exposure to cross-link the polymer, but the substrate temperature did not exceed 180 degrees C. With this method guides could be fabricated on a range of substrates up to 125 cm in diameter, including those with multilayer metallization for multichip modules, providing optical interconnect capability. Microprism reflecting surfaces were fabricated in the waveguides to couple light out normal to the substrate. All the processing was compatible with normal semiconductor fabrication.

InP–InGaAs cleaved-cavity lasers are routinely used in long-wavelength optical transmission systems, packaged with a discrete pin photodiode back-facet monitor used to provide feedback to control the laser output power. This conventionally requires two separate wafer-fabrication processes, and individual testing, cleaving, and assembly at the chip level. The handling of cleaved bars, facet-coating, testing, and mounting is labour-intensive and expensive. Etching mirror facets during wafer processing makes it possible in a single fabrication process to fabricate lasers with an integrated back facet monitor, and do on-wafer testing without further alignment and assembly. This has now been achieved with the following technologiesf (i) laser epitaxial layers used for light detection as well as emission, (ii) reactive-ion-etched (RIE) (CH4–Ar)-etched mirror facets, and (iii) electrical interconnects by metal airbridges. Integrated laser and (or) monitors with RIE-processed facets have threshold currents as low as 30 mA, efficiencies of 0.14 mW mA−1, and monitor efficiencies of 0.1 mA mW−1. Excellent uniformity was observed across a 2 in (1 in = 2.54 cm) wafer. The lower threshold currents (27 mA) observed for cleaved facet lasers from the same wafer indicate that the processed facet quality can be further improved; the optimum RIE process results in etched facets with a facet angle about 5° off vertical. Packaged devices have been successfully operated at speeds up to 1 Gb s−1 for both laser and monitor. Preliminary reliability studies are described.

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006