Modelocked fiber laser resonators may be coupled with optical amplifiers. An isolator optionally may separate the resonator from the amplifier. A reflective optical element on one end of the resonator having a relatively low reflectivity may be employed to couple light from the resonator to the amplifier. Enhanced pulse-width control may be provided with concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers may also be included in the laser cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth may be obtained by matching the dispersion value of the grating to the inverse of the dispersion of the intra-cavity fiber. Frequency comb sources may be constructed from such modelocked fiber oscillators. Low dispersion and an in-line interferometer that provides feedback may assist in controlling the frequency components output from the comb source.

Pulsed laser sources

A telemetry apparatus and method for communicating data from a down-hole location through a borehole to the surface is described including a light source, an optical fiber being placed along the length of the wellbore and receiving light from the light source, a transducer located such as to produce a force field (eg a magnetic field) across the optical fiber and its protective hull without mechanical penetration of the hull at the down-hole location, one or more sensors for measuring down-hole conditions and/or parameters, a controller to provide a modulated signal to the magnetic field generator, said modulated signal being under operating conditions representative of measurements by the one or more sensors, and an optical detector adapted to detect changes in the light intensity or polarization of light passing through the fiber

Borehole telemetry system

An apparatus for acoustic concentration of particles in a fluid flow includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

Acoustic concentration of particles in fluid flow

A laser utilizes a cavity design which allows the stable generation of high peak power pulses from mode-locked multi-mode fiber lasers, greatly extending the peak power limits of conventional mode-locked single-mode fiber lasers. Mode-locking may be induced by insertion of a saturable absorber into the cavity and by inserting one or more mode-filters to ensure the oscillation of the fundamental mode in the multi-mode fiber. The probability of damage of the absorber may be minimized by the insertion of an additional semiconductor optical power limiter into the cavity.

Mode-locked multi-mode fiber laser pulse source

The present invention includes an apparatus and corresponding method for concentrating analytes within a fluid flowing through a tube using acoustic radiation pressure. The apparatus includes a function generator that outputs a radio frequency electrical signal to a transducer that transforms the radio frequency electric signal to an acoustic signal and couples the acoustic signal to the tube. The acoustic signal is converted within the tube to acoustic pressure that concentrates the analytes within the fluid.

Ultrasonic analyte concentration and application in flow cytometry

The authors describe acousto-optic modulators for optical fibers, fabricated by the deposition of thin zinc-oxide transducers onto specially lapped glass capillary tubes. By exposing the inner surface of the capillary and contacting it to an optical fiber of the same diameter, a good Hertzian contact can be easily attained, providing efficient throughput of acoustic energy at frequencies in excess of 1 GHz. A phase modulator for a single-mode fiber has been fabricated in such a manner, achieving a maximum phase retardation of 1.0 rad/W input electrical power at 416 MHz. Its frequency, power, and polarization characteristics are discussed. Also presented are data from a frequency shifter/modal coupler for a two-mode optical fiber. This device achieved 6% power coupling from the fundamental optical mode to the second-order mode with 500 mW input power at 1.03 GHz. Single sideband modulation was observed with >19-dB suppression of the unwanted sideband. The authors also describe the design of an optical tap using the same technology. >

B.T. Khuri-Yakub

Papers

Acousto-optic modulators for optical fibers using Hertzian contact with a grooved transducer substrate