In this work, we present the fabrication technology of a monolithically integrated photonic platform combining key components for optical coherence tomography (OCT) imaging, thereby including a photonic interferometer, a collimating lens, and a 45◦ reflecting mirror that directs the light from the interferometer to the collimator. The proposed integration process simplifies the fabrication of an interferometric system and inherently overcomes the complexity of costly alignment procedures while complying with the necessarily stringent optical constraints. Fabricated waveguide characterization shows total optical losses as low as 3 dB, and less than 1 dB of additional loss due to the Si 45◦ mirror facet. The alignment standard deviation of all components is within 15 nm. The integrated lens profile achieves a divergence angle smaller than 0.7◦, which is close to that of a collimator. The proposed photonic platform provides the premise for low-cost and small-footprint single-chip OCT systems.@en

The high aspect ratio and the porous nature of spatially oriented forest-like carbon nanotube (CNT) structures represent a unique opportunity to engineer a novel class of nanoscale assemblies. By combining CNTs and conformal coatings, a 3D lightweight scaffold with tailored behavior can be achieved. The effect of nanoscale coatings, aluminum oxide (Al2O3) and nonstoichiometric amorphous silicon carbide (a-SiC), on the thermal transport efficiency of high aspect ratio vertically aligned CNTs, is reported herein. The thermal performance of the CNT-based nanostructure strongly depends on the achieved porosity, the coating material and its infiltration within the nanotube network. An unprecedented enhancement in terms of effective thermal conductivity in a-SiC coated CNTs has been obtained: 181% compared to the as-grown CNTs and Al2O3 coated CNTs. Furthermore, the integration of coated high aspect ratio CNTs in an epoxy molding compound demonstrates that, next to the required thermal conductivity, the mechanical compliance for thermal interface applications can also be achieved through coating infiltration into foam-like CNT forests.@en

In this paper, we present an electrothermal biaxial MEMS actuator system, which provides x-A nd y-direction scanning for a fully integrated 3-D optical coherence tomography (OCT) scanner. An angular scanning range of 8° (corresponding to a 7-mm linear scanning range in both directions) is achieved, with an average power consumption of 150 mW. The resonant frequency is 668 and 297 Hz for x-A nd y-directions, respectively. With a footprint of only 2.5×2.5mm², this system is part of a device which also integrates an optical waveguide and a collimated lens on the same chip, thus making the fully integrated, self-aligned, and miniaturized 3-D OCT scanners feasible.

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A highly miniaturized, single-chip, large scanning range MOEMS scanner is demonstrated. This intrinsically-aligned, monolithically integrated device uses small angular displacement to provide a linear scanning range of 2000 μm in the lateral and 1000 μm in the vertical direction, at a working distance of 2 cm, with an average operating power lower than 170 mW. Within a footprint of only 7×10 mm², the presented system fully integrates a photonic interferometer comprising a mirror, a silicon microlens and the MEMS actuator into a single chip, thus offering an unprecedentedly miniaturized scanning solution. The monolithic integration of all photonic components provides intrinsic alignment and excludes coupling losses often encountered in systems composed of discrete parts. No additional attenuation of the optical signal is observed during device operation. This small and high-performance device is suitable as complete system-on-chip for commercial, portable imaging applications.

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In this work, we present the results of integrated Ge detectors grown on a Si photonic platform for sensing applications. The detectors are fabricated on a passive photonic circuit for maximum coupling efficiency. Measurement results at 1300 nm wavelength show a responsivity of 0.2 A/W and very low dark current levels. For a voltage range between 0 and −10 V, the dark current is better than 0.1 nA which is crucial for highly sensitivity devices and applications, like Optical Coherence Tomography. @en

Two novel MEMS actuator systems (a torsional one and a deflecting one) for a new self-aligned integrated 3D optical coherent tomography (OCT) scanner are reported. These new systems, with a footprint of 2.5mm×2.5 mm each, provide a χ and y scanning range of 730 μm (tilting range of 8°) with an average power consumption of 150 mW. As the device integrates a silicon collimating micro lens, an optical waveguide and a MEMS actuator system on a single chip, it provides a considerable decrease in optical losses thanks to the intrinsic alignment obtained during fabrication, while significantly reducing the complexity and time that assembly and packaging of separate components demand, therefore making fully integrated, miniaturized 3D OCT scanners feasible.

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In this paper we present the characterization of the coefficient of thermal expansion (CTE) of in-situ doped polycrystalline SiC thin films, obtained by low pressure chemical vapor deposition (LPCVD). The material is characterized using V-beam actuators on which the temperature coefficient of resistance (TCR) and the in-plane displacement versus current are measured. A CTE value of 4.3 ± 0.4 ppm/K is obtained in the temperature region of 20°C to 300°C. This value is used in a finite element modeling (FEM) simulation of vertical SiC-SiO2 bimorph beams. For an actuator length of 700 μm, width of 100 μm and layer thickness of 2 μm, a displacement up to 200 μm can be obtained.@en

We present Si microlenses fabricated using dry ICP plasma etching of silicon and thermal photoresist reflow. The process is insensitive to thermal reflow time and it can be easily incorporated into fabrication flows for complex optical systems. Using this process, we were able to fabricate microlenses with diameter of 150 μm, radius of curvature of 682 μm and with a surface roughness of only 25 nm.@en