MEMS variable optical attenuator

A MEMS device for optically attenuating an optical beam, comprising:

• a microelectronic substrate having a generally planar surface;
• a microelectronic actuator disposed on the generally planar surface of said microelectronic substrate;
• an optical shutter disposed on the generally planar surface of said microelectronic substrate, wherein said optical shutter is actuatable by said microelectronic actuator and is adapted to attenuate any percentage of optical power within an optical power range;
• an electrostatic clamping element operably connected to said optical shutter that allows for said optical shutter to be electrostatically clamped at a desired attenuation position;
• an electrostatic contact on said substrate which is electrostatically coupled to said electrostatic clamping element;
• and
• means for applying an electrostatic force between said electrostatic clamping element and said electrostatic contact.

A system for variable optical attenuation, the system comprising:

• a MEMS variable optical attenuator having a microelectronic substrate having a generally planar surface, a microelectronic actuator disposed on the generally planar surface of said microelectronic substrate, an optical shutter disposed on the generally planar surface of said microelectronic substrate, an electrostatic clamping element operably connected to said optical shutter that allows for said optical shutter to be electrostatically clamped at a desired attenuation position;
• an electrostatic contact on said substrate which is electrostatically coupled to said electrostatic clamping element;
• and
• a voltage source for applying an electrostatic force between said electrostatic clamping element and said electrostatic contact.

A method for optical attenuation using a MEMS variable optical attenuator having a microelectronic substrate having a generally planar surface, a microelectronic actuator disposed on the generally planar surface of said microelectronic substrate, an optical shutter disposed on the generally planar surface of said microelectronic substrate, an electrostatic clamping element disposed on said substrate, the method comprising the steps of:

• activating the microelectronic actuator;
• actuating the optical shutter by way of the microelectronic actuator so that the optical shutter is placed in a prescribed attenuation position so as to intersect at least a portion of a plane through which an optical beam passes;
• activating electrostatically the clamping element thereby locking the optical shutter at the prescribed attenuation position;
• and
• deactivating the microelectronic actuator while the optical shutter is locked at the prescribed attenuation position.

A method of fabricating a MEMS variable optical attenuator comprising:

• forming an oxide layer on a generally first planar surface of a microelectronic substrate;
• forming a silicon layer on the oxide layer;
• defining a mechanical structure of the attenuator in the silicon layer, the mechanical structure defining a thermal arched beam actuator, an actuator member and an optical shutter;
• releasing a portion of the silicon layer from the substrate by etching away the oxide layer underlying the arched beams of the thermal arched beam actuator and the actuator member;
• doping at least a portion of the silicon layer to provide a predetermined conductivity;
• and
• etching a second surface of the microelectronic substrate, opposite the first surface, and etching the oxide layer underlying the optical shutter to release the optical shutter from the substrate.