Micromachined VOA with perpendicularly aligned tapered optic fibers

Abstract

Two new micromachined VOAs(Variable Optical Attenuator), which have a micromirror with ultra-smooth surface, are presented and are compared with each other with respect to each different actuator type with same mirror structure. A couple of tapered fibers are perpendicularly aligned using the reflection of a micromirror. By moving the micromirror parallel or vertical direction to the mirror surface, some part of transmitting light can be attenuated with the principle of leaked light or misaligned light. This paper shows the two features of performance of the new two type VOAs. The one is that a micromirror with ultra-smooth surface gives the good optical performances of the VOA and the second is that the two new type VOAs have different the optical characteristics, such as polarization dependent loss(PDL), wave dependent loss(WDL) and return loss(RL), because of the different optical path or different optical attenuated method by different actuator. In this paper, the structure of reflector type VOA is fabricated using silicon micromachining process. Using SOI(silicon-on-insulator) wafer with 80μm device layer and 3 μm oxide layer, structure is patterned by ICP (Inductively Coupled Plasma) deep etch process which is followd by thermal oxidation for improved surface roughness, HF oxide layer etching, releasing and Au sputtering to form mirror surfaces and interconnection pads. This paper pays attention to the importance of the final optical fiber alignment, which may play a key role in the optical performance of the VOA.