The invention relates to optical modulation devices and, in particular, monolithically integrated optical modulation devices. Disclosed herein is a monolithically integrated optical modulation device (200) that comprises: an input optical port (210); an output optical port (215); and an optical waveguide for guiding light from the input optical port to the output optical port. A portion of the optical waveguide is split into at least two branches. The waveguide is configured to cause a net 180° change in direction of the light while guiding said light from the input optical port to the output optical port such that the input optical port and the output optical port are positioned on a first edge of the device. At least some of the net 180° change in direction is achieved within the branches of the waveguide.

A method for setting a heating condition for thermal aging of each of fiber Bragg gratings, includes: determining, based on a correspondence (Ed) between a temperature coefficient of each of the fiber Bragg gratings and a demarcation energy Ed of each of the fiber Bragg gratings, a first lower limit Ed.sub.min of the demarcation energy Ed such that the temperature coefficient is not more than a desired upper limit .sub.max; and setting the heating condition for thermal aging of each of the fiber Bragg gratings such that the demarcation energy Ed is not less than the first lower limit Ed.sub.min.

Optical fiber filters and uses thereof are presented. In typical implementations, there is provided a FBG taking deleterious light out of a fiber core without reflecting it into the fiber core. It also allows the unhindered transmission of useful light at a wavelength outside of the spectral band covered by the deleterious light. The filter couples the incoming deleterious light to cladding modes propagating in the opposite direction without coupling the incoming useful light to core or cladding modes propagating in the opposite direction. The filter may for example be useful as a Raman or ASE filter in a laser cavity of other optical devices.

A method of making an optical fiber sensor device for distributed sensing includes generating a laser beam comprising a plurality of ultrafast pulses, and focusing the laser beam into a core of an optical fiber to form a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to a longitudinal axis of optical fiber. Also, an optical fiber sensor device for distributed sensing includes an optical fiber having a longitudinal axis, a core, and a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to the longitudinal axis of the optical fiber. Also, a distributed sensing method and system and an energy production system that employs such an optical fiber sensor device.

A method of making an optical fiber sensor device for distributed sensing includes generating a laser beam comprising a plurality of ultrafast pulses, and focusing the laser beam into a core of an optical fiber to form a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to a longitudinal axis of optical fiber. Also, an optical fiber sensor device for distributed sensing includes an optical fiber having a longitudinal axis, a core, and a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to the longitudinal axis of the optical fiber. Also, a distributed sensing method and system and an energy production system that employs such an optical fiber sensor device.

Optical fiber filters and uses thereof are presented. In typical implementations, there is provided a FBG taking deleterious light out of a fiber core without reflecting it into the fiber core. It also allows the unhindered transmission of useful light at a wavelength outside of the spectral band covered by the deleterious light. The filter couples the incoming deleterious light to cladding modes propagating in the opposite direction without coupling the incoming useful light to core or cladding modes propagating in the opposite direction. The filter may for example be useful as a Raman or ASE filter in a laser cavity of other optical devices.

Various examples and systems are provided for enhancing optical fibers for sensing temperature and/or strain at low temperatures (e.g., 1.8K to 77K or lower). An enhanced optical fiber for distributed sensing can comprise a core, a cladding surrounding the core, and a coating surrounding the cladding. A coefficient of thermal expansion (CTE) of the coating is greater than a CTE of silica and/or a Young's modulus (E) of the coating is greater than an E of silica.

Back scattering in an optical waveguide at an operating wavelength is controlled by adjusting an optical phase of light propagating in the waveguide at one or more locations along the waveguide. A portion of the back scattered light is tapped off near an input port and coupled into a photodetector. A controller detects changes in the photodetector signal and adjusts an optical phase tuner configured to control the optical phase of light in the waveguide at the selected location or locations. The optical phase tuner may be configured to vary the refractive index of at least a portion of the waveguide.

A window can comprise a first side and a second side substantially parallel to the first side. The window can comprise an optical grating operatively positioned with respect to one of the first side and the second side. The optical grating can be used to determine a temperature at or near the respective one of the first side and the second side.

Optical fiber filters and uses thereof are presented. In typical implementations, there is provided a FBG taking deleterious light out of a fiber core without reflecting it into the fiber core. It also allows the unhindered transmission of useful light at a wavelength outside of the spectral band covered by the deleterious light. The filter couples the incoming deleterious light to cladding modes propagating in the opposite direction without coupling the incoming useful light to core or cladding modes propagating in the opposite direction. The filter may for example be useful as a Raman or ASE filter in a laser cavity of other optical devices.