1D and 2 ordered structures for photonic crystals by using magnetic fluid films

Structural evolution along the edges of magnetic fluid micro-strips under external magnetic fields perpendicular or parallel to the strip surface is investigated in this paper. For the perpendicular fields, it was found that when the field strength increased the structure evolves from an originally monodispersed state to a disordered column state, and then to several levels of ordered structures. For the ordered structure state, a one-dimensional periodic structure resulted under lower field strengths, and with an increase in field strength, more columns formed. Hence a two-dimensional ordered array of columns was achieved. Further experimental results showed that the ordered structure can be manipulated by adjusting control parameters, such as field strength, sweep rate, fluid concentration, strip width, and strip thickness. On the hand, one-dimensional periodic chain array is achieved under parallel fields. This ordered structure is also found to be tunable by tuning the control parameters. These results lay the groundwork for utilizing controllable ordered structures in magnetic fluid micro-strips to develop potential applications in photonic-crystal waveguides or filters.