Shaping light with microtechnology components has been possible for many years. The Texas Instruments digital
micromirror device (DMD) and all types of adaptive optics systems are very sophisticated tools, well established and
widely used. Here we present, however, two very dedicated systems, where one is an extremely simple MEMS-based
tunable diffuser, while the second device is complex micromirror array with new capabilities for femtosecond laser pulse
shaping. Showing the two systems right next to each other demonstrates the vast options and versatility of MOEMS for
shaping light in the space and time domain.
We show the first results of a linear 100-micromirror array capable of modulating the phase and amplitude of the spectral
components of femtosecond lasers. Using MEMS-based reflective systems has the advantage of utilizing coatings tailored
to the laser wavelength range. The innovative features of our device include a novel rotational, vertical comb-drive actuator
and an X-shaped, laterally reinforced spring that prevents lateral snap-in while providing flexibility in the two degrees of
freedom of each mirror, namely piston and tilt. The packaging utilizes high-density fine-pitch wire-bonding for on-chip
and chip-to-PCB connectivity. For the first deployment, UV-shaped pulses will be produced to coherently control the
dynamics of biomolecules.
There are many potential applications for MEMS micromirror devices for femtosecond pulse shaping applications. Their
broadband reflectivity gives them an advantage in comparison to devices such as liquid crystal- and acousto-optical modulators
because of the possibility to directly shape UV pulses in the range 250 - 400 nm, and thus address UV-absorbing
molecules. The identification and discrimination of biomolecules which exhibit almost the same spectra has sparked
some interest in the last years as it allows real-time, environmental and optical monitoring. Here, we present the last
developments using the Fraunhofer IPMS MEMS phase former capable of accomplishing such goals.
We are developing a linear array of micromirrors designed for optical, femtosecond laser pulse shaping. It is a bulkmicromachined
device, capable of retarding or diminishing certain laser frequencies in order to perform phase and amplitude modulation within a frequency band spanning the UV to the near-infrared. The design consists of a linear array of mirrors fixed on either side by springs. They feature two degrees of freedom: Out-of-plane motion for phase shifting and
rotational motion for binary amplitude modulation, both realized using vertical comb drives. The first applications will include femtosecond discrimination experiments on biomolecules.