Fast and robust piezoelectric axicon mirror.

In this Letter, we demonstrate the first high-speed piezoelectric axicon mirror. We achieve a usable aperture of 10 mm up to the maximum radius of the robust, 300 µm thick mirror substrate using a floating boundary condition. The highly aspheric, conical shape is programmed into the device by ring-shaped electrodes, for which we have developed an automated optimization strategy for their individual electrode potentials. In addition, we developed a simple control circuit, in which the conical profile can be programmed and adjusted with just one control signal. The device is fabricated by rapid prototyping to avoid cleanroom processing. The tunable mirror features a resonance frequency of 10 kHz and a static deflection of 5.8 µm at a surface deviation of 63 nm, and is thus able to generate a quasi-Bessel beam.

Tunable MEMS axicon mirror arrays.

Highly aspheric reflective micro-optics for the generation of quasi-nondiffracting beams are of great interest for a wide variety of applications. However, up to now it was impossible to fabricate tunable arrays of these elements. In this Letter, we demonstrate the first array of purely reflective tunable microelectromechanical systems (MEMS) microaxicon mirrors with a conical shape and a continuous surface. The actuation is achieved by thermal expansion in a solid state design and the tuning range allows for large conical angles and is able to form concave as well as convex axicons. The deflection of the mirror surface and the propagation of the resulting quasi-Bessel beams have been characterized to prove the functionality of the device.

Sub-3-cycle vortex pulses of tunable topological charge.

Novel types of reflective spiral micro-electro-mechanical systems were used to generate few-cycle vortex pulses of variable topological charge from a Ti:sapphire laser oscillator. The phase profile of these components was controlled by varying the temperature. The temporal properties of the pulses were characterized with spatially resolved nonlinear autocorrelation. The beam structure resembles a slightly distorted Laguerre-Gaussian distribution. The different topological charges were indicated by detecting Poynting-vector maps with a programmable Shack-Hartmann sensor of enhanced angular sensitivity.

Complex three-dimensional high aspect ratio microfluidic network manufactured in combined PerMX dry-resist and SU-8 technology.

In this paper we present a new fabrication method that combines for the first time popular SU-8 technology and PerMX dry-photoresist lamination for the manufacturing of high aspect ratio three-dimensional multi-level microfluidic networks. The potential of this approach, which further benefits from wafer-level manufacturing and accurate alignment of fluidic levels, is demonstrated by a highly integrated three-level microfluidic chip. The hereby achieved network complexity, including 24 fluidic vias and 16 crossing points of three individual microchannels on less than 13 mm(2) chip area, is unique for SU-8 based fluidic networks. We further report on excellent process compatibility between SU-8 and PerMX dry-photoresist which results in high interlayer adhesion strength. The tight pressure sealing of a fluidic channel (0.5 MPa for 1 h) is demonstrated for 150 µm narrow SU-8/PerMX bonding interfaces.