Abstract: Methods providing distributed temperature and strain measurements are disclosed. Brillouin pump laser pulses having a Brillouin pump frequency are coupled into a first end of an optical fiber. Brillouin Stokes and Anti-Stokes probe laser beams are coupled into a second end of the fiber. The Stokes probe laser beam has a Stokes probe frequency. The Anti-Stokes probe laser beam has an Anti-Stokes probe frequency. The Stokes and Anti-Stokes probe frequencies and the pump frequency are included in a Brillouin frequency band. A train of Rayleigh seed pulses are coupled into the fiber. Each of the seed pulses of the train has a respective different frequency included in a Rayleigh frequency band. Frequencies of the Brillouin frequency band are coupled to a Brillouin detector, and Rayleigh backscatter signals are coupled to a Rayleigh detector. Brillouin and Rayleigh detector outputs are used to calculate the measurements. Related sensors are also disclosed.

Abstract: Brillouin fiber sensors can provide distributed measurements of parameters of interest over long distances in a fiber by measuring the Brillouin frequency shift as a function of position along the fiber. The Brillouin frequency shift may be determined, to within a small fraction of the Brillouin linewidth, by establishing a series of lasing modes that experience Brillouin amplification at discrete spatial locations in a test fiber. A linewidth narrowing and high intensity associated with the lasing transition enable precise measurements of the lasing frequency associated with each of the lasing modes. The Brillouin frequency may be determined based on the lasing frequency.

Abstract: Multiplexed fiber optic sensors are able to monitor a multitude of sensor positions along an optical fiber from a single interrogation point. A long-standing goal is to increase the length of fiber and the number of multiplexed sensors without significantly compromising performance or increasing the size, weight, power and cost of the fiber and interrogation system. A technique is provided for performing extremely long-range, multiplexed fiber optic strain sensing in an efficient manner. This technique utilizes a serial optical frequency comb based interrogation system to probe an array of sensors placed along a single optical fiber.

Abstract: Optical frequency combs are used for a wide range of applications, some of which require precise control of the amplitude and phase of individual comb teeth. A technique is provided for tooth-level optical frequency comb control. A frequency comb may include a plurality of comb teeth that are separated from one another by a comb frequency spacing. This technique includes generating a train of control pulses, each of the control pulses being frequency-locked to a corresponding tooth of an optical frequency comb to be controlled. The tooth-level control of the frequency comb is enabled via stimulated Brillouin scattering using the train of control pulses.

Abstract: A dynamic Brillouin fiber sensor that is immune to fluctuations in the power, frequency, or polarizing state of the pump and probe beams is described herein. A new measurand that combines information from the complex Stokes and anti-Stokes interactions is provided to extract the absolute Brillouin frequency shift while rejecting the majority of noise sources that may limit the performance of current slope-assisted Brillouin optical time domain analysis systems.

Abstract: Brillouin fiber sensors can provide distributed measurements of parameters of interest over long distances in a fiber by measuring the Brillouin frequency shift as a function of position along the fiber. The Brillouin frequency shift may be determined, to within a small fraction of the Brillouin linewidth, by establishing a series of lasing modes that experience Brillouin amplification at discrete spatial locations in a test fiber. A linewidth narrowing and high intensity associated with the lasing transition enable precise measurements of the lasing frequency associated with each of the lasing modes. The Brillouin frequency may be determined based on the lasing frequency.

Abstract: A dynamic Brillouin fiber sensor that is immune to fluctuations in the power, frequency, or polarizing state of the pump and probe beams is described herein. A new measurand that combines information from the complex Stokes and anti-Stokes interactions is provided to extract the absolute Brillouin frequency shift while rejecting the majority of noise sources that may limit the performance of current slope-assisted Brillouin optical time domain analysis systems.

Abstract: A method of interferometric optical sensing via spatial demodulation includes emitting a laser beam; splitting the laser beam into a reference beam and an interrogation beam; converting a desired signal into a change in the optical path of the interrogation beam via an optical sensor; and capturing the reference beam and the interrogation beam via a camera, wherein the interrogation beam is incident to the camera at a first angle and the reference beam is incident to the camera at a second angle different from the first angle, thereby causing an interference pattern at the camera.

Abstract: Embodiments of the present invention are directed to systems and methods for trapping and holding airborne particles. In the various embodiments, an optical trap is provided which uses a focused hollow-beam for trapping and holding both absorbing and non-absorbing airborne particles. The optical trap comprises: a trapping region where a particle can be present to be trapped; a light source for generating a coherent beam of light; optics for forming a hollow beam having a ring geometry from the coherent beam of light; and a focusing element for focusing the hollow beam to a point in the trapping region. In this arrangement, the particle is trapped at or near the focal point of the focused hollow beam.

Abstract: Embodiments of the present invention are directed to systems and methods for trapping and holding airborne particles. In the various embodiments, an optical trap is provided which uses a focused hollow-beam for trapping and holding both absorbing and non-absorbing airborne particles. The optical trap comprises: a trapping region where a particle can be present to be trapped; a light source for generating a coherent beam of light; optics for forming a hollow beam having a ring geometry from the coherent beam of light; and a focusing element for focusing the hollow beam to a point in the trapping region. In this arrangement, the particle is trapped at or near the focal point of the focused hollow beam.