Photonic Integrated Circuits (PICs) play a crucial role in shaping the future of quantum technology, communications, and sensor applications. With a transparency window ranging from ultraviolet to visible to mid-infrared light and a high bandgap of 6.2 eV, aluminium nitride (AlN) is ideal for a wide range of optical applications.
Within the upcoming PIC platform, we have designed, fabricated, and examined various ring resonators, comprised of coupling structures, waveguides and ring resonators, tailored for the optical L-band (1565 nm – 1625 nm). The arrangement of the coupling structures for incoupling the light from a laser source and outcoupling of the light to a detector allows for automatic probing and mapping of various structure modifications. With grating couplers integrated on the chip, these optical structures can be linked to a tunable laser source and a detector via optical fibers.
We compare the fabrication results of the optical nanostructures for the AlN-based devices with previous results from Si3N4-based structures. To ensure the ideal structure dimensions and to minimize deviations from the simulated design values, the AlN dry etch process has been investigated and improved.
Pyroelectric detectors are used for gas analysis and flame detection because of their fast response and excellent performance. Most pyroelectric devices are based on monocrystalline lithium tantalate or pyroelectric lead zirconate titanate thin films deposited on a silicon (Si) substrate. In comparison, recently discovered pyroelectric-doped hafnium oxide (HfO2) offers the possibility of manufacturing completely complementary metal-oxide-semiconductor (CMOS)-compatible devices on large Si wafers. This is a promising approach to simplifying mass production of the sensor element and realizing new sensor structures with a high performance. Si substrates were structured with trenches and filled with thin-doped HfO2 layers by atomic layer deposition to multiply the pyroelectric current responsivity. An effective pyroelectric coefficient of up to 1300 μC / m2 / K was measured. Micromechanical structuring of the 6-in Si wafers was used to improve the thermal conversion of the sensor element. The applied plasmonic absorbers increase the infrared light absorption to >80 % for the spectral range of 3 to 5 μm, which was determined using Fourier transform infrared reflection measurements. In the first step, the performance of the sensor element was evaluated with an analog transimpedance amplifier with a feedback resistance of 5 GΩ. A specific detectivity D * > 1 · 107 cm√Hz / W was measured for the frequency range of 1 to 10 Hz. In addition, an application-specific integrated circuit was designed for the electrical signal conditioning to build a fully CMOS-compatible pyroelectric detector. It offers a simple to manufacture, flexible configuration, and digital communication interface with a signal-to-noise performance close to analog detectors. We present the measurement results of different sensor elements and detector types.
This work deals with in-line measurement techniques for quantification of important microsystems parameters and
related scattering caused by the process conditions. Material properties, mechanical stress but also geometrical
dimensions and their tolerances are characterized by indirect method, based on specially designed test-structures. This
method involves a data fusion process that combines numerically calculated and experimentally determined information
to estimate sought parameters. Laser Doppler Vibrometrie is used to determine the frequency response function (FRF) of
the test-structure and find out their Eigenfrequencies. For the numerical simulation of the test-structures a parametrical
finite element (FE) model is used and a series of pre-stressed modal analyses have been performed. Hence the
dependence of the Eigenfrequencies on parameters of interest is obtained. The comparison to the measured frequencies
yields the values of the desired parameters. The test-structures are designed, produced and used for microsystems
manufacturing monitoring in Bonding and Deep Reactive Ion Etching (BDRIE) processes. An optimization of the teststructures'
form for a nontrivial goal function is shown. Measurement results of the presented technique are comparable
with results of common characterization methods. The presented technique is both in-situ and non-destructive.
This contribution describes the investigation of the reasons for overload failure and overload reaction based on linear
vibration theory by decomposition of the complex reaction into resonant mode reactions and on observation of the
reaction. An impulse specific peak deflection (ISPD) is derived as a general characteristic property of a certain shock. It
is applicable to predict the mechanical deflection of a certain resonant mode of an arbitrary resonant frequency due to a
shock. This is further analyzed and proofed by scanning Laser Doppler interferometer (SLDI) measurement on the
example of a Fabry Perot interferometer based tunable infrared filter. The results from ISPD prediction are compared to
SLDI measurements and to finite element analysis results.
A novel characterization method for MEMS devices based on the combination of measurement and simulation results is introduced on the example of an electrostatically actuated micro mirror array. The aim of this method is to determine geometrical parameters and built-in mechanical stress on the base of the measured eigenfrequencies. A Laser Doppler interferometer and a signal analyzer are used to determine the frequency response function (FRF) of the micro mechanical structure and the eigenfrequencies are calculated. For the numerical simulation of the micro mirrors behavior the finite element (FE) model is used and a series of nonlinear coupled-field analysis and pre-stressed nonlinear modal analysis have been performed. Hence the dependence of the eigenfrequencies on geometrical parameters and built-in mechanical stress is obtained. The comparison to the measured frequencies yields in values for the searched parameters that are mean values for the entire micro mechanical structure. The presented method is very efficient because it determines several characteristics of a MEMS device on the base of only one measured frequency response function. The article demonstrates that a sufficient accuracy is achieved and stress values are calculated that are hardly ascertainable using common measurement methods.
The paper deals with a novel setup of a Hadamard transform spectrometer (HTS) which encoding mask is realized by a micro mirror array. In contrast to other applications of an HTS the mirrors of the array are not statically switched but dynamically driven to oscillate at the same frequency. The Hadamard transform is obtained by shifting the phase shift of oscillation. The paper gives a brief introduction in the entity of the Hadamard transform technique. The driving and detection circuits are presented and first measurement results are discussed.
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