Electrically tunable fabry-perot interferometer, an intermediate product an electrode arrangement and a method for producing an electrically tunable fabry-perot interferometer

An electrically tunable Fabry-Perot interferometer, comprising:

• a substrate (130);
• a first mirror structure (101-105, 108) on the substrate (130);
• a second, movable mirror structure (113, 116-120), the first and second mirror structures comprising a first mirror (51) and a second mirror (52) which are substantially parallel;
• a Fabry-Perot cavity (123) between the first mirror (51) and the second mirror (52), whereupon the cavity (123) has been formed by providing a sacrificial layer (112) using a polymer on the first mirror structure, and by removing at least a part of the sacrificial layer after providing the second mirror structure;
• electrodes (106, 506, 115, 515) for controlling the distance between the mirrors, on the edges of the cavity (123) of the interferometer, between the first and second mirror layers, is a support made of polymer for supporting the second, movable mirror (52), wherein at least one of the electrodes (115, 515) is electrically floating, and in that the control structure of the mirrors (51), (52) comprises a first fixed electrode (106, 506) and a second fixed electrode (106, 550), configured so that a capacitance between the floating electrode (115, 515) and the said first fixed electrode (106, 506) is a changing capacitance, and the capacitance between the floating electrode (115, 515) and the said second fixed electrode (106, 550) is configured to be a fixed capacitance, such that the said fixed capacitance (Cfixed, 53) and changing capacitance (Ccontrol, 54) are connected in series for applying an AC voltage as
• the control voltage between the said first fixed electrode (106, 506) and the said second fixed electrode (106, 550) across the capacitances (53, 54) as connected in series for controlling the distance between the first mirror (51) and the second mirror (52) of the structure.

An intermediate product of an electrically tunable Fabry-Perot interferometer, comprising:

• a substrate (130);
• a first mirror structure (101-105, 108) on the substrate (130);
• a second, movable mirror structure (113, 116-120), the first and second mirror structures comprising a first mirror (51) and a second mirror (52) which are substantially parallel;
• a sacrificial layer (112) containing polymer material between the first and second mirror structures;
• electrodes (106, 506, 115, 515) for controlling the distance between the mirrors (51), (52), wherein the intermediate product comprises a chip cut out from a semiconductor wafer, in that at least one of the electrodes (115, 515) is electrically floating, and in that the control structure of the mirrors (51), (52) comprises a first fixed electrode (106, 506) and a second fixed electrode (106, 550), configured so that the capacitance between the floating electrode (115, 515) and the said first fixed electrode (106, 506) is configured to be a changing capacitance, and the capacitance between the floating electrode (115, 515) and the said second fixed electrode (106, 550) is configured to be a fixed capacitance, such that the said fixed capacitance (Cfixed, 53) and the changing capacitance (Ccontrol, 54) are connected in series, for applying an AC voltage as the control voltage between the said first fixed electrode (106, 506) and second fixed electrode (106, 550) across the capacitances as connected in series for controlling the distance between the first mirror (51) and the second mirror (52) of the structure.