Northrop Grumman Systems Corporation

Northrop Corporation

Trw Limited

Hiroshi Komine

Michael G Wickham

Robert R Rice

Stephen John Brosnan

Joshua E Rothenberg

William H Long

Eric C T Cheung

Peter Moshchansky Livingston

John Ballato

Hagop Injeyan

David B Cohn

James G Ho

Peter Anthony Thielen

Eric C Cheung

Chun-Ching Shih

Joseph M Fukumoto

James M Zamel

Sameh S Wanis

Hacop Injeyan

Charles Phillip Asman

One embodiment of the invention includes a method for forming an optical fiber. The method comprises providing a preform having a core material and a glass cladding material surrounding the core material. The method also comprises drawing the preform at a temperature that is greater than a melting temperature of the core material to form a drawn fiber. The method further comprises cooling the drawn fiber to form the optical fiber having a crystalline fiber core and a cladding that surrounds the crystalline fiber core and extends axially along a length of the crystalline fiber core.

Optical fiber systems and methods

A laser frequency converter includes a first substrate material forming a first planar surface that includes a first nonlinear material situated along a portion of the first planar surface of the first substrate material to perform a frequency conversion of a laser signal. The frequency converter includes a second substrate material forming a second planar surface and separated by a distance from the first planar surface of the first substrate material. The second substrate material includes a second nonlinear material situated along a portion of the second planar surface of the second substrate material to perform the frequency conversion of the laser signal in conjunction with the first non-linear material. The second nonlinear material is offset from the first nonlinear material along an axis of propagation for the laser signal.

Distributed thermal system for nonlinear optical frequency conversion

A method is provided for forming an optical fiber amplifier. The method comprises providing a composite preform having a gain material core that includes one or more acoustic velocity varying dopants to provide a longitudinally varying acoustic velocity profile along the gain material core to suppress Stimulated Brillouin Scattering (SBS) effects by raising the SBS threshold and drawing the composite preform to form the optical fiber amplifier.

Optical fiber amplifier and methods of making the same

At least one transducer of an apparatus in one example is configured to generate a first standing wave field within a cavity. The first standing wave field exerts a first field-induced force to cause a plurality of particles within the cavity to align in a desired configuration. The at least one transducer is configured to generate a second standing wave field within the cavity. The second standing wave field causes one or more of the plurality of particles within the cavity to fuse into the desired configuration.

Standing wave field induced force

A system and method for combining plural low power light beams into a coherent high power light beam by means of a diffractive optical element operating as both a beam combiner and beam sampler. An oscillation source transmits a master signal that is split into plural beams propagating at a common wavelength. Each beam is phase locked by a corresponding phase modulator according to a phase correction signal. The beams are directed through a fiber array to the diffractive optical element to allow efficient coherent combination of the beams at a desired diffraction order. The diffractive optical element includes a periodic sampling grating for diffracting a low power sample beam representative of the combined beam. A phase detection stage detects phases of constituent beams in the sample beam from which the phase correction signals are derived and fed back to the phase modulators. The diffractive optical element may be further modified to collimate beams diverging from the fiber array and to focus the sample beam onto a phase detector.

Method and system for coherent beam combining using an integrated diffractive beam combiner and sampler

Encircled far field energy is substantially increased by modifying the near field energy distribution of radiation from each fiber in an emitting array. Each beamlet output from a fiber is modified to have a generally uniform cross-sectional energy distribution, using a pair of aspheric optical elements selected for that purpose. The optical elements may be refractive or reflective. The modified beamlets combine to form a composite output beam with a generally uniform energy distribution. Preferably, the composite beam is subject to an array-wide inverse transformation to a near-Gaussian distribution, further enhancing the encircled far field energy and providing a more efficient high power laser source. Further gains in efficiency are achieved by selecting a fiber bundle pattern, lens array pattern and lens shape that together result in a high fill factor.

Method and apparatus for optimizing the target intensity distribution transmitted from a fiber coupled array

A laser array architecture scalable to very high powers by closely stacking fiber amplifiers, but in which the output wavelength is selectable to be in the visible or ultraviolet region, without being restricted by the wavelengths usually inherent in the choice of fiber materials. A pump signal at a fundamental frequency is amplified in the fiber amplifier array and input to an array of nonlinear crystals that function as harmonic generators, producing an output array at a desired harmonic of the fundamental frequency. A phase detection and correction system maintains the array of outputs in phase coherency, resulting in a high power output with high beam quality, at the desired frequency. The array of nonlinear crystals may a single array to produce a second harmonic output frequency, or a combination of multiple cascaded arrays configured to produce a selected higher order harmonic frequency.

Scalable harmonic laser source and method

A method is provided for seeding laser system () for single longitudinal mode oscillation. The method includes coupling laser system () to be seeded for single mode output to a seed laser radiation source (). Next, the frequency capture range () and spacing () of the axial modes () of the cavity () of the laser system () are determined. A seed spectrum () is then generated from the seed laser radiation source () with a bandwidth () corresponding to the axial mode spacing (). The seed spectrum () includes a comb of discrete frequency components () with one or more of the discrete frequency components () being within the frequency capture range () of at least one of the axial modes (). The seed spectrum () is then injected into the cavity () such that at least one of the axial modes () oscillates with the seed radiation.

Robust seeding technique for single mode laser oscillation

A hybrid laser source including a solid state laser driven by an array of fiber laser amplifiers, the inputs of which are controllable in phase and polarization, to compensate for distortions that arise in the solid state laser, or to achieve desired output beam properties relating to direction or focus. The output beam is sampled and compared with a reference beam to obtain phase and polarization difference signals across the output beam cross section, at spatial positions corresponding with the positions of the fiber laser amplifiers providing input to the solid state laser. Therefore, phase and polarization properties of the output beam may be independently controlled by predistortion of these properties in the fiber laser amplifier inputs.

Laser source comprising amplifier and adaptive wavefront/polarization driver

A laser array architecture scalable to very high powers by fiber amplifiers, but in which the output wavelength is selectable, and not restricted by the wavelengths usually inherent in the choice of fiber materials. A pump beam at a first frequency is amplified in the fiber amplifier array and is mixed with a secondary beam at a second frequency to yield a frequency difference signal from each of an array of optical parametric amplifiers. A phase detection and correction system maintains the array of outputs from the amplifiers in phase coherency, resulting in a high power output at the desired wavelength. A degenerate form of the architecture is disclosed in an alternate embodiment, and a third embodiment employs dual wavelength fiber amplifiers to obtain an output at a desired difference frequency.

Scalable wavelength shifted laser source and method

Briefly, the present invention relates to a system for combining the output light beams of a plurality of semiconductor laser diodes, for example, to form a combined light beam with increased brightness. The output light beams from the semiconductor laser diodes are coupled to a plurality of optical fibers forming a fiber coupled diode array. The optical fibers forming the fiber coupled diode array are coupled to a dual clad optical fiber with a central core. The output light beams from the optical fibers from the fiber coupled diode array are coupled to the inner cladding of a dual clad optical fiber. A Stokes seed source is applied to the central core, and the inner-clad diode light acts as a pump source to amplify the Stokes beam by stimulated Ramans scattering, thereby transferring power from the inner cladding into Stokes beam in the central core. The configuration in accordance with the present invention provides a Stokes output light beam with a relatively higher brightness level than known techniques which merely combine the output light beams from a plurality of semiconductor diodes and eliminates the need for a relatively precise alignment and the cost associated with the lenses required by known systems.

Brightness enhancement of diode light sources

A high-energy optical beam generator providing a desired output waveform. The generator includes a master oscillator, such as a mode-locked laser, to generate an input beam, a first dispersive element to decompose the input beam into frequency components, a set of phase and amplitude modulators to modulate the frequency components individually, a set of power amplifiers to amplify the frequency components individually, and a second dispersive element to recombine the amplified and modulated frequency components into a single output beam. Phase control electronics control the modulators to provide the desired waveform for the output beam, based on its intended application and on sensed characteristics of the input beam and the output beam.

High energy arbitrary waveform source

A compact fiber packaging system for fiber lasers is provided that comprises a series of spools nested inside one another for efficient volume utilization. The spools comprise an inner spool nested inside at least one outer spool to form a module. Generally, the fiber lasers are wrapped around the inner spool, and then around successive outer spools as required to form the module. Furthermore, the modules may be stacked to form a fiber assembly. The compact fiber packaging system further comprises devices and methods for minimizing thermal gradients between fibers and for removing Waste heat from the system. Additionally, the available volume is further utilized by disposing equipment and materials for operation of the fibers inside a hollow center defined by the inner spool, between the nested spools, and adjacent the nested spools.

Compact packaging of multiple fiber lasers

An optical system () that couples pump light () into a signal fiber () of a fiber array laser/amplifier. The system () includes a tapered light guide (TLG) () optically coupled to the signal fiber () so that the signal light propagates into a single-mode core () extending through the TLG (). The TLG () includes a diffraction grating aperture () through which the pump light () is coupled into the TLG (). An array of diode emitters () is positioned adjacent to the diffraction grating aperture () so that the pump light () is diffracted into the TLG (). The pump light () is reflected off of the interface () between the TLG () and air. The angle of the pump light () as it is reflected off of an interface () between the TLG () and air decreases so that the pump light () is contained within the signal fiber ().

Method for coupling diode array light into an optical fiber

A seed laser apparatus is disclosed. It comprises a distributed feedback laser system for transmitting a dithered optical signal having a frequency versus time characteristic that is represented by a triangular waveform and an optical medium including a plurality of optical signal paths, each path including an optical fiber and a fiber amplifier. The optical medium is characterized by stimulated Brillouin scattering (SBS) having a response time, whereby the period of the triangular waveform is equal to the round-trip transit time in the fiber or shorter than the response time of the SBS.

Growing community of inventors

Torrance, CA, United States of America

Hiroshi Komine