In this paper, we illustrate the design and testing of new silicon microstructures, fabricated by means of a conventional planar process. These "Venetian-blind" structures consist of arrays of narrow, rectangular suspended masses (width =31 /spl mu/m, length =400 /spl mu/m, thickness =15 /spl mu/m), which can be tilted using electrostatic actuation. Characterization of their static and dynamic behavior was performed with optical methods. The diffraction patterns in monochromatic light were analyzed and vibration measurements were performed by means of semiconductor laser feedback interferometry: experimental data on the tilt angle as a function of the applied voltage and on the resonance frequencies are reported. A maximum tilt angle of approximately 1.9/spl deg/ was obtained with a driving voltage in the range of 70-95 V. All the tested devices showed resonance frequencies higher than 80 kHz, which is fast enough (i.e., switching time in the millisecond range) for future use in optical interconnections. Numerical analyses were performed to evaluate the coupled electromechanical behavior of the microstructures, confirming the observed experimental behavior.

Testing of "Venetian-Blind" silicon microstructures with optical methods

We present investigations of a new miniaturized NIR spectrometer
with a size of only 1088 cm3, and a MOEMS-scanninggrating
chip as a main element. It works currently in a spectral range of
1200 to 1900 nm with a resolution of less than 10 nm using only one
single InGaAs diode as a detector. One entire spectral measurement is
done within 6 msec, calculated by a digital signal processor, which is
included in the spectrometer. The MOEMS-scanning-grating chip is resonantly
driven by a pulsed voltage of up to 36 V, has a grating plate 3
3 mm2, and reaches deflection angles of ±8 deg at 25 V. Control and
investigation of the deflection angle, the static deformation, the spectral
efficiency, and the mechanical shock resistance are key parameters to
reach the spectrometer specifications. Results of these measurements
and their influence on the spectrometer are discussed. Special etch control
structures to monitor the fabrication process of the grating structure
in the nanometer range, which can be easily done by microscopic inspection,
are also presented.

J. Talghader

Papers

Introduction to the Issue on Optical Microsystems