World-Class Resources > 200mm Wafer Fabrication > CNSE Expertise > Optics CNSE has designed, modeled, fabricated and characterized numerous Micro Optical Electro Mechanical (MOEMs) devices at our facility.

One such device CNSE has developed is novel active optical filter fabricated in Porous Silicon (Psi). This device allows the active selection desired optical wavelengths. The device is based on a tunable membrane optical filter which is based on a Fabry-Perot interferometer employing two Bragg reflectors separated by an adjustable air gap. The gap is adjusted with an integrated thermally controlled Micro bimorph actuator. The Bragg reflectors contain alternating layers of high and low porosities. These layers were created by electrochemical etching of p+ type silicon wafers by varying the applied current during etching process. A Micro bimorph actuator is incorporated into the structure to control the movement of the top DBR mirror which changes the cavity thickness. By varying the applied current, the proposed filter can tune the transmitted wavelength of the optical signal.

 

Electrochemical Etching: SEM Cross-sections

Double Cavity PSi Structure

 

PSi Diffractive Optical Element (DOE) devices

 

The device shown above includes freestanding structures for light beam steering, filtering and splitting. This device contains an actuator that controls the movement of the device which contains a PSi multilayer film. PSi DOEs with 1-D and 2-D spatially distributed optical properties of desired periodicity can be created using periodically patterned PR as masks for electrochemical etching. The membrane device forms a concave mirror which has been demonstrated to be a reconfigurable chip-to-chip optical interconnects.

The output of a CCD imager clearly demonstrates the switching capabilities of a DOE array.