Abstract: An optical-fiber filter is provided. The optical-fiber filter includes an optical fiber having a first end-face and an opposing second end-face. The first end-face and the second end-face set a fiber length. The first end-face and the second end-face are coated with reflective coatings. When an optical beam emitted from a laser is coupled into one of the first end-face or the second end-face, an optical beam output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations.

Abstract: A hollow-core optical-fiber filter is provided. The hollow-core optical-fiber filter includes a hollow-core optical fiber having a first end-face and an opposing second end-face. The first end-face and the second end-face set a fiber length. The hollow-core optical-fiber filter also includes a first reflective end-cap positioned at the first end-face and a second reflective end-cap positioned at the second end-face. When an optical beam from a laser is coupled into one of the first end-face or the second end-face, an optical output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations.

Abstract: Systems and methods for a hollow core resonant filter are provided. In one embodiment, a hollow-core fiber resonant cavity comprises: a hollow-core fiber having a first and second ends; a first and a second pigtail fiber each of solid core fiber material. A tip of the first pigtail is optically aligned with the first-end to couple light from the first pigtail to the hollow core fiber across a first free-space gap. A tip of the second pigtail is optically aligned with the second-end to couple light from the second pigtail to the hollow-core fiber across a second free-space gap. The tip of the second pigtail is coated to reflect light received from the second-end back across the second free-space gap into the second-end. The tip of the first pigtail is coated to reflect light received from the first-end back across the first free-space gap into the first-end.

Abstract: Methods and systems for improved fiber optic gyroscopes for operation in non-atmospheric environments are provided. In one embodiment, an integrated optical circuit for an interferometer subject to non-atmospheric conditions comprises: a first section of waveguide within a Lithium crystalline structure that is exposed to an electrical field, the first section of waveguide being a Titanium-diffused waveguide region; a second section of waveguide within the Lithium crystalline structure that is not within the first section of the waveguide, the second section of waveguide being a proton-exchange waveguide region; a stitch coupling the first section of waveguide to the second section of waveguide; and a third section of waveguide configured to combine reciprocal light beams to produce an interference pattern, wherein at least one of the reciprocal light beams pass through the first section of waveguide and the second section of waveguide prior to producing the interference pattern.

Abstract: A hollow-core optical-fiber filter is provided. The hollow-core optical-fiber filter includes a hollow-core optical fiber having a first end-face and an opposing second end-face. The first end-face and the second end-face set a fiber length. The hollow-core optical-fiber filter also includes a first reflective end-cap positioned at the first end-face and a second reflective end-cap positioned at the second end-face. When an optical beam from a laser is coupled into one of the first end-face or the second end-face, an optical output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations.

Abstract: An optical-fiber filter is provided. The optical-fiber filter includes an optical fiber having a first end-face and an opposing second end-face. The first end-face and the second end-face set a fiber length. The first end-face and the second end-face are coated with reflective coatings. When an optical beam emitted from a laser is coupled into one of the first end-face or the second end-face, an optical beam output from the opposing end-face has a narrow linewidth and low frequency noise fluctuations.

Abstract: Methods and systems for improved fiber optic gyroscopes for operation in non-atmospheric environments are provided. In one embodiment, an integrated optical circuit for an interferometer subject to non-atmospheric conditions comprises: a first section of waveguide within a Lithium crystalline structure that is exposed to an electrical field, the first section of waveguide being a Titanium-diffused waveguide region; a second section of waveguide within the Lithium crystalline structure that is not within the first section of the waveguide, the second section of waveguide being a proton-exchange waveguide region; a stitch coupling the first section of waveguide to the second section of waveguide; and a third section of waveguide configured to combine reciprocal light beams to produce an interference pattern, wherein at least one of the reciprocal light beams pass through the first section of waveguide and the second section of waveguide prior to producing the interference pattern.

Abstract: An integrated optical circuit includes a first waveguide portion of a first material. The first waveguide portion includes an input-port section terminating in a junction section from which first and second branch sections are formed. Second and third waveguide portions are respectively coupled to the first and second branch sections. The second and third waveguide portions are diffused with a second material different from the first material. First and second modulators are respectively coupled to the second and third waveguide portions. Each of the modulators provides respective modulating voltages generating respective electric fields. The second and third waveguide portions are coupled to the first and second branch sections at respective locations where the electric fields are substantially zero.