A laser source or a plurality of laser sources in a photonic integrated circuit (PIC) are provided with an electrical contact that is either segmented or is connected to a series of vernier resistor segments for supply of current to operate the laser source. In either case, at least one segment of the laser contact or at least one vernier resistor segment can be trimmed in order to vary the amount of current supplied to the laser source resulting in a change to its current density and, thus, a change in its operational wavelength while maintaining the current supplied to the laser source constant.

A communication apparatus includes an optical fiber along which radiation can be transmitted; an optical fiber grating formed within the optical fiber, the optical fiber grating having a structure, and configured to reflect radiation at a particular wavelength; and an instrument coupled to the grating and configured to controllably modify the structure of the grating, thereby changing the wavelength at which the grating reflects radiation. A communication system including the communication apparatus is also described, along with a method of communicating a signal.

A communication apparatus includes an optical fiber along which radiation can be transmitted; an optical fiber grating formed within the optical fiber, the optical fiber grating having a structure, and configured to reflect radiation at a particular wavelength; and an instrument coupled to the grating and configured to controllably modify the structure of the grating, thereby changing the wavelength at which the grating reflects radiation. A communication system including the communication apparatus is also described, along with a method of communicating a signal.

An optical transducer is provided. A measuring portion of the transducer may be exposed to a high pressure and fluids when the optical transducer is deployed (e.g., in a wellbore or other industrial setting). The transducer may include an optical waveguide with a first portion that forms a first seal that isolates an instrumentation portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed. The transducer may also include a second seal with a stack of material elements that contact a second portion of the optical waveguide to also isolate the instrumentation portion of the transducer from exposure to the high pressure and fluids to which the measuring portion may be exposed.

A wavelength-stabilised narrow-linewidth mode-locked picosecond laser system comprises a laser cavity which includes an amplifier, a mode-locking element, and a fiber Bragg grating which acts as a narrowband reflector. The system includes a mount to which the fiber Bragg grating is mounted under tension, a tension control system to adjust the tension, and a measurement device to provide a measurement output related to a current operating wavelength of the fiber Bragg grating. A microcontroller or other controller wavelength-stabilises the laser by controlling the tension control system responsive to the measured wavelength.

A sensor for measuring flow speed of a fluid, comprising: a light-absorbing optical fiber having a fiber Bragg grating inscribed in the fiber; wherein light is emitted into the light-absorbing optical fiber to heat the optical fiber and the fiber Bragg grating, and when the fluid passes over the sensor, the flow speed of the fluid is determined by the rate of heat loss from the sensor, and the temperature of the sensor is determined from the wavelength shift of the central wavelength of the fiber Bragg grating.

An optical sensor for detecting a chemical species in a sample, the optical sensor comprising a single mode fibre having a fibre Bragg grating, wherein the fibre Bragg grating has a refractive index profile, the optical sensor arranged to provide an output optical signal based on a positive detection of the chemical species in the sample, wherein the sample, upon illumination, emits a sample optical signal having an optical frequency signature comprising a plurality of spectral lines that are associated with the chemical species, wherein the refractive index profile is associated with the optical frequency signature, and the fibre Bragg grating is arranged to be modulated to generate the output optical signal.