Kurt De Mesel

Thin-film devices fabricated with benzocyclobutene adhesive wafer bonding

In this paper, we present and elaborate on die to wafer bonding technology with benzocyclobutene (BCB). This technology allows to fabricate a variety of reliable waferbonded components in a fairly simple way using only standard cleanroom equipment. We demonstrate the fabrication of passive devices such as microring resonators, as well as active components such as lasers and LEDs. We show good performance of these devices by presenting measurements of their characteristics. Furthermore, these devices were subjected to damp-heat testing, demonstrating the good quality of the BCB-bonding procedure. Finally, due to the low thermal conductivity of BCB, thermal management needs some attention. We present an analysis of the thermal problem and suggest a possible solution.

Compact spot-size converters with fiber-matched antiresonant reflecting optical waveguides

We propose a concept for InGaAsP-InP 1.55-microm lasers integrated with spot-size converters based on modal interference between the modes of the structure formed by an active waveguide and an underlying fiber-matched antiresonant reflecting optical waveguide. Simulation results show that the spot-size converters exhibit low transformation loss, and narrowed far-field emission patterns (10 degrees x 20 degrees) and reduce the coupling loss to standard single-mode fibers from 8 to 2.6 dB over lengths approximately 200 microm shorter than the adiabatic concept. A tolerant design to fabrication variations is also proposed, which could be realized by standard processing techniques.

Simple-to-fabricate and highly efficient spot-size converters using antiresonant reflecting optical waveguides

We report on a new concept for InGaAsP-InP 1.55 μm lasers with integrated spot-size converters based on antiresonant reflecting optical waveguides (ARROW). The mode expanders consist of a laterally tapered active region on top of a fiber-matched passive slab waveguide. The large slab mode is laterally confined by an antiresonant configuration of a couple of lateral waveguides defined in the same fabrication process as the active ridge. This feature makes the presented spot-size transformer as simple to fabricate as a standard waveguide, only requiring a planar growth step and a single conventional etch process. The fabricated tapers exhibit a low transformation loss and reduce the coupling loss to standard single-mode fibers from 8 to 4 dB. We also analyze by simulation two variants of the concept proposed in this work, including a taper structure for a buried waveguide, which are expected to show better performance. Simulation results show fiber-coupling efficiencies as low as 2.4 and 1.1 dB for both variants.