Electrothermally actuated Fabry-Pe/spl acute/rot tunable filter with a high tuning efficiency

We report on a electrothermally actuated Fabry-Pe/spl acute/rot wavelength tunable filter with a high tuning efficiency by using surface micromachining. To prevent a current flowing through the mirror, a Wheatstone bridge structure is introduced. Because the full wafer is monolithically grown and the electrodes are formed in a single step, the fabrication processes is simple and reproducible. As the current flows through the two parallel thermal actuators, the top mirror moves away from the bottom mirror so that a sticking problem does not occur. The maximum voltage for the 69-nm wavelength tuning by using a 5.2-μm-thick filter structure is only 1.7 V and the high tuning efficiency of /spl sim/75 nm/mW is achieved.