Thermo-mechanical behaviour of a micromirror for laser-to-fibre active alignment using bimorphs with breakable tethers

We will present a novel micromirror design in which tethered bimorph strips are used for mirror active alignment including beam steering and position fixing. A micromirror is attached to bimorphs that are prestressed at room temperature. A series of tethers link the bimorphs to the substrate to restrain their deformation. Breaking a tether by joule heating allows the deformation of the bimorph to increase, changing the mirror position and orientation for precision alignment. With a large number of tethers, an optimum alignment can be achieved after breaking a selected group of tethers. Experimental results of the devices fabricated confirm the beam steering and position fixing designed.