Systems and methods for measuring temperature in an environment by creating a first beam having an energy of about 50 mJ/pulse, and a pulse duration of about 100 ps. A second beam is also created, having an energy of about 2.3 mJ/pulse, and a pulse duration of about 58 ps. The first beam and the second beam are directed into a probe region, thereby expressing an optical output. Properties of the optical output are measured at a sampling rate of at least about 100 kHz, and temperature measurements are derived from the measured properties of the optical output. Such systems and methods can be used to measure temperature in environments exhibiting highly turbulent and transient flow dynamics.

A frequency stabilizer includes: a delay line interferometer that receives an optical signal corresponding to one frequency mode of a pulsed laser, divides and transmits the received optical signal to a reference arm and a delay arm including an optical fiber delay line, and then outputs an interference signal between signals passing through the reference arm and the delay arm; a photoelectric converter that converts the interference signal into an electrical signal; a mixer that generates a baseband signal of the electrical signal by mixing a carrier frequency signal; and a feedback controller that transmits a control signal generated based on the baseband signal to the pulsed laser. The optical signal passing through the delay arm is weighted with a delay time caused by the optical fiber delay line compared to the optical signal passing through the reference arm, and the optical signal passing through the delay arm is frequency shifted to a carrier frequency of an oscillator. A carrier-envelope offset frequency of the pulsed laser is stabilized by an offset frequency stabilizer.

A laser amplifier module having an enclosure includes an input window, a mirror optically coupled to the input window and disposed in a first plane, and a first amplifier head disposed along an optical amplification path adjacent a first end of the enclosure. The laser amplifier module also includes a second amplifier head disposed along the optical amplification path adjacent a second end of the enclosure and a cavity mirror disposed along the optical amplification path.

The optical fiber of the present invention includes a core, and a cladding that is provided on an outer periphery of the core and has a refractive index lower than a refractive index of the core region. In the optical fiber of the present invention, a V value representing a normalized frequency of an LP.sub.02 mode is greater than or equal to 4.8 and less than or equal to 6.4.

A system includes a master oscillator configured to generate a first optical beam and a beam controller configured to modify the first optical beam. The system also includes a PWG amplifier configured to receive the modified first optical beam and generate a second optical beam having a higher power than the first optical beam. The second optical beam has a power of at least about ten kilowatts. The PWG amplifier includes a single laser gain medium configured to generate the second optical beam. The system further includes a feedback loop configured to control the master oscillator, PWG amplifier, and beam controller. The feedback loop includes a laser controller. The laser controller may be configured to process wavefront information or power in bucket information associated with the second optical beam to control an adaptive optic or perform a back-propagation algorithm to provide wavefront correction at an output of the PWG amplifier.

An amplification optical fiber according to the present invention includes: a core doped with an active element, through which multi-mode light propagates; an inner cladding that surrounds the core and has a refractive index lower than that of the core; and an outer cladding that surrounds the inner cladding and has a refractive index lower than that of the inner cladding. The inner cladding has a polygonal outline in a cross section perpendicular to the longitudinal direction, and the inner cladding has a permanent twist applied by turning around the central axis of the core.

A laser device is a laser device that includes an output unit that outputs seed light to a light amplifying unit. The output unit has a light source unit that outputs, as the seed light, rays of light with a plurality of wavelengths lying within a gain range of the light amplifying unit, and a seed light control unit that controls an intensity-time waveform of the seed light output from the light source unit.

Nonlinear interferometers include a nonlinear optical medium that is situated to produce a conjugate optical beam in response to a pump beam and a probe beam. The pump, probe, and conjugate beams propagate displaced from each other along a common optical path. One of the beams is selectively phase shifted, and the beams are then returned to the nonlinear medium, with the selectively phase shift beam phase shifted again. The nonlinear medium provides phase sensitive gain to at least one of the probe or conjugate beams, and the amplified beam is detected to provide an estimate of the phase shift.

A frequency stabilizer includes: a delay line interferometer that receives an optical signal corresponding to one frequency mode of a pulsed laser, divides and transmits the received optical signal to a reference arm and a delay arm including an optical fiber delay line, and then outputs an interference signal between signals passing through the reference arm and the delay arm; a photoelectric converter that converts the interference signal into an electrical signal; a mixer that generates a baseband signal of the electrical signal by mixing a carrier frequency signal; and a feedback controller that transmits a control signal generated based on the baseband signal to the pulsed laser. The optical signal passing through the delay arm is weighted with a delay time caused by the optical fiber delay line compared to the optical signal passing through the reference arm, and the optical signal passing through the delay arm is frequency shifted to a carrier frequency of an oscillator. A carrier-envelope offset frequency of the pulsed laser is stabilized by an offset frequency stabilizer.

A swept light source of the present invention keeps a coherence length of an output beam long over an entire sweep wavelength range. A gain of a gain medium is changed with time in response to a wavelength sweep and the coherence length is kept maximum. The gain of the gain medium is kept close to a lasing threshold and an unsaturated gain range of the gain medium is narrowed over the entire sweep wavelength range. An SOA current waveform data acquiring method of driving while keeping the coherence length long, a novel coherence length measuring method, and an optical deflector suitable for the swept light source are also disclosed.