Niels Quack

Submicrometer Hall devices fabricated by focused electron-beam-induced deposition

Hall devices having an active area of about (500 nm)(2) are fabricated by focused electron-beam-induced deposition. The deposited material consists of cobalt nanoparticles in a carbonaceous matrix. The realized devices have, at room temperature, a current sensitivity of about 1 V/AT, a resistance of a few kilo-ohms, and can be biased with a maximum current of about 1 mA. The room-temperature magnetic field resolution is about 10 muT/Hz(1/2) at frequencies above 1 kHz.

50×50 digital silicon photonic switches with MEMS-actuated adiabatic couplers

We report on monolithically integrated 50×50 digital silicon photonic switches with MEMS actuation, sub-microsecond switching time, low optical insertion loss (<;9.6dB), high extinction ratio (50dB), broadband operation (1400-1700nm), and compact footprint (7.6×7.6mm2).

Monolithic 50x50 MEMS Silicon Photonic Switches with Microsecond Response Time

We report on 50×50 MEMS-actuated silicon photonic switches with 16V switching voltage and microsecond switching time. 2,500 MEMS cantilever 1×2 waveguide switches have been integrated on 9mm×9mm chips.

Enhancement of mechanical Q for low phase noise optomechanical oscillators

A self-sustained Radiation-Pressure driven MEMS ring OptoMechanical Oscillator (RP-OMO) attaining an anchor-loss-limited mechanical Q-factor of 10,400 in vacuum has posted a best-to-date phase noise of -102 dBc/Hz at a 1 kHz offset from a 74 MHz carrier, more than 15 dB better than the best previously published mark [1]. While enhanced optical and mechanical Q both serve to lower the optical threshold power required to obtain oscillation, it is the mechanical Q that ends up having the strongest impact on phase noise [2], much as in a traditional MEMS-based oscillator [3]. This motivates a focus on increased mechanical Q-a challenge in previous such devices measured in air-and requires measurement in the absence of gas-damping using a custom optical vacuum measurement system. The improved phase noise performance of these RP-OMOs is now on par with many conventional MEMS-based oscillators and is sufficient for the targeted chip-scale atomic clock application.

Mid-Infrared Tunable Resonant Cavity Enhanced Detectors

Mid-infrared detectors that are sensitive only in a tunable narrow spectral band are presented. They are based on the Resonant Cavity Enhanced Detector (RCED) principle and employing a thin active region using IV-VI narrow gap semiconductor layers. A Fabry-Pérot cavity is formed by two mirrors. The active layer is grown onto one mirror, while the second mirror can be displaced. This changes the cavity length thus shifting the resonances where the detector is sensitive. Using electrostatically actuated MEMS micromirrors, a very compact tunable detector system has been fabricated. Mirror movements of more than 3 μm at 30V are obtained. With these mirrors, detectors with a wavelength tuning range of about 0.7 μm have been realized. Single detectors can be used in mid-infrared micro spectrometers, while a detector arrangement in an array makes it possible to realize Adaptive Focal Plane Arrays (AFPA).

64×64 Low-loss and broadband digital silicon photonic MEMS switches

We report on monolithically integrated 64×64 broadband digital silicon photonic MEMS switches with sub-microsecond switching time (0.9 μs), high extinction ratio (65 dB), low on-chip insertion loss (5.1 dB), broadband operation (1460-1580 nm wavelength) and compact footprint (7×7 mm²).

Electrostatically actuated micromirror for resonant cavity enhanced detectors

This paper presents the design, fabrication and measurement results of a vertically moving, electrostatically actuated micromirror. The single crystalline silicon substrate allows the design of a symmetrical and mechanically stable mirror suspension while keeping a geometry with high fill factors and maintaining elasticity and thus keeping the actuation voltage below 25 V. The device is being developed for the use in a tunable resonant cavity enhanced detector (RCED) for the mid-infrared (Arnold, 2005). RCEDs make use of a standing wave formed in an optical cavity and are only sensitive at the resonances. The wavelengths of the resonances are hereby depending on the distance of the two cavity mirrors (Unlu, 1995). Such narrowband detector systems are sought- after in multispectral infrared (IR) thermography or infrared spectroscopy (Musca, 2005).

Large-port-count MEMS silicon photonics switches

Highly integrated optical circuit switch (OCS) with large port counts (~100×100) is achievable by combining silicon photonics and MEMS technologies. We will review the design trade-offs, performance scaling, and the current state of the art.

Flip Chip Packaging of Digital Silicon Photonics MEMS Switch for Cloud Computing and Data Centre

We report on the flip chip packaging of Micro-Electro-Mechanical System (MEMS)-based digital silicon photonic switching device and the characterization results of 12 × 12 switching ports. The challenges in packaging N² electrical and 2N optical interconnections are addressed with single-layer electrical redistribution lines of 25 <italic>μ</italic>m line width and space on aluminum nitride interposer and 13° polished 64-channel lidless fiber array (FA) with a pitch of 127 <italic>μ</italic>m. 50 <italic>μ</italic>m diameter solder spheres are laser-jetted onto the electrical bond pads surrounded by suspended MEMS actuators on the device before fluxless flip-chip bonding. A lidless FA is finally coupled near-vertically onto the device gratings using a 6-degree-of-freedom (6-DOF) alignment system. Fiber-to-grating coupler loss of 4.25 dB/facet, 10^–11 bit error rate (BER) through the longest optical path, and 0.4 <italic>μ</italic>s switch reconfiguration time have been demonstrated using 10 Gb/s Ethernet data stream.

Self-aligned VCSEL-microlens scanner with large scan range

This paper reports on the design, fabrication and optical characterization of a self-aligned microlaser scanning system consisting of a vertical cavity surface emitting laser (VCSEL) source and a MEMS-actuated microlens scanner. The alignment and the spacing between the VCSEL and the MEMS scanner are achieved through lithographically patterned alignment grooves and precision micro-beads. Horizontal displacements of ±70 μm, corresponding to scanning angles of ±7°, have been demonstrated.