5 - MEMS devices

Elecrostatically driven deformable mirror is the basic element of beam-shaping array chip. It is possible to focus or defocus the incoming ligth. There are addressable elecrode pads on the Si substrate, a couple of electrodes under each mirror plate. The mirror plate bends when the elecrostatic force pulls ist edges onto the chip surface.

Submicron grating structures are replicated in inorganic glass with hot embossing process. The dies for replication are made from materials resistant to high temperature and a special ceramic coating. With a moulding time of only a few seconds and commercial float glass, low-cost mass-producing of sensor chips is possible. The embossed stucture works as optical filter.

Electromechanically driven optical microshutters enable high-speed light switching. The animation shows a single shutter of the array. Each microshutter consists of a shutter blade, a suspension beam, and several electrodes and stoppers. The stoppers are necessary to avoid short-circuits between the beam and the electrodes when they come in close contact. Under each shutter blade, a hole is made in such a way that it is closed or open when the blade is attracted by one of the electrodes.

Aperture moduleted diffusers (AMDs) are used for excimer laser beam shaping applications. AMDs are made as micrometer sized optical patterns manufactured in quartz wafers. There are more different AMD shapes, such as hexagonal, quadrupole, etc. shown below, which determines the far-field distribution of laser beam.

The bottom, middle and top distributed Bragg reflector in the VCSL act together with the air gap to set the boundary conditions that determine the laser's output wavelength. Electrons flow from the substrate to the contacts atop the middle distributed Bragg reflector, tunneled into a narrow stream by an aperture in the insulating oxide layer. Applying electrostatic force to the cantilever alters the thickness of the air gap between the cantilevered distributed Bragg reflector and the body of the laser, thus changing the resonator's frequency and tuning the output wavelength.