Systems and methods for performing adaptive filtering are disclosed. The drive unit first drives the focusing optics to a specific position on an information recording medium. In addition, a plurality of first candidacy pose information is generated in an error range of the first pose information. The exterior fins of the first and second heat sinks are aligned with each other, and a snap-type connecting structures are formed on terminuses of the exterior fins. A trench is formed in the side region of the active region by using the first mask and the isolation region as a mask.