Optical fiber sensors, tunable filters and modulators using long-period gratings

An optical sensor comprising;

• a light source;
• an optical waveguide having a core surrounded by a cladding layer, the optical waveguide optically coupled to the light source and configured to transmit light through the core from the light source to a selected location;
• an optical grating formed in the optical waveguide, the grating being configured to create a resonance to affect the light transmitted from the light source;
• and
• a layer of environmentally sensitive material applied to a surface of the optical waveguide and overlaying at least a portion of the optical grating, wherein a change in the environment causes a change in the layer of environmentally sensitive material affecting the resonance created by the grating, the change of resonance in the grating causing light to be extracted from the core into the cladding layer and transmitted through the cladding layer in a direction away from the light source.

An optical device for affecting the light in an optical waveguide having a core and a cladding layer, comprising:

• a first grating formed in the optical waveguide, the first grating being operable to selectively extract light transmitted through the core of the waveguide into the cladding layer, the extracted light thereby being transmitted through the cladding layer;
• an active element applied to a side of the optical fiber in at least partially overlapping alignment with the first grating;
• and
• a second grating formed in the optical waveguide at a location in the optical waveguide downstream of the first grating.

An optical filter comprising:

• an optical waveguide;
• a grating formed in the optical waveguide for extracting light from a core portion of the waveguide into a cladding portion of the waveguide, the extracted light being transmitted in a guided mode along the waveguide within the cladding portion;
• and
• an active element applied to a surface of the optical waveguide and overlaying at least a portion of the grating, the active element being responsive to a light signal applied to the active element to cause a change in a characteristic of the light transmitted within the cladding layer along the optical waveguide.

An optical device, comprising:

• an optical waveguide having a core covered by a cladding layer;
• a first long-period grating formed in the core of the waveguide;
• a second long-period grating formed in the core of the waveguide downstream of the first grating;
• a blocking element formed in the core of the optical waveguide at a location in the core between the first grating and the second grating;
• and
• wherein light transmitted through the core of the waveguide is selectively extracted by first grating from the core and transmitted through the cladding layer around the blocking element.

A fiber optic device, comprising:

• an optical fiber having a core and a cladding layer;
• a long-period grating located in the core of the optical fiber and operable to extract light from the core and transmit the light through the cladding layer;
• and
• a coating layer located on an outer surface of the cladding layer at a location along the optical fiber that is different from the location of the grating, the coating layer having a characteristic that is sensitive to an external input to change the propagation of the light through the cladding.

A fiber optic device, comprising:

• an optical fiber having a core and a cladding layer;
• a long-period grating located in the core of the optical fiber for extracting light from the core, the extracted light being transmitted in a guided mode along the fiber within the cladding layer;
• and
• an active device mounted on the outer surface of the cladding layer, the active device having a characteristic that is sensitive to an external input to change the propagation of the light within the cladding.