Lockheed Martin Corporation

Aculight Corporation

Matthias P Savage-Leuchs

Eric C Honea

Lawrence A Borschowa

Jason D Henrie

Christian E Dilley

Mark P Bendett

Fabio Di Teodoro

Christopher D Brooks

James M Owen

Robert W Royse

Tracy W Vatter

Charles A Lemaire

Anping Liu

Jonathon D Wells

John D Minelly

Eric C Eisenberg

Barton James Jenson

Sean M Courtney

Christian D Dilley

Khushvinder S Brar

Jonathan D Wells

An optical system, apparatus, or method can comprise or implement a seed module to generate and output electromagnetic radiation at a predetermined amplitude and at a predetermined wavelength. The seed module can include at least one non-hollow core optical fiber and at least one hollow core optical fiber. One at least one non-hollow core optical fiber can be optically coupled to one at least one hollow core optical fiber. The non-hollow core optical fiber and the hollow core optical fiber may receive and pass electromagnetic radiation emitted from a laser diode or amplifier.

Hollow core fiber laser system, apparatus, and method

An apparatus, method and system that uses a Q-switched laser or a Q-seed source for a seed pulse signal having a controlled high-dynamic-range amplitude that avoids and/or compensates for pulse steepening in high-gain optical-fiber and/or optical-rod amplification of optical pulses. Optionally, the optical output is used for LIDAR or illumination purposes (e.g., for image acquisition). In some embodiments, well-controlled pulse shapes are obtained having a wide dynamic range, long duration, and not-too-narrow linewidth. In some embodiments, upon the opening of a Q-switch in an optical cavity having a gain medium, the amplification builds relatively slowly, wherein each round trip through the gain medium increases the amplitude of the optical pulse. Other embodiments use quasi-Q-switch devices or a plurality of amplitude modulators to obtain Q-seed pulses. These configurations provide optical pulses having wide dynamic ranges that ameliorate problems of pulse steepening, non-linear spectral broadening and the like in very-high-power MOPA devices.

Q-switched oscillator seed-source for MOPA laser illuminator apparatus and method

A ring laser includes a large-core rare-earth-doped fiber ring-connected with a free-space path having an electro-optic switch, output coupler, and intracavity band-pass filter to enforce lasing operation in narrow wavelength range. In some cavity-dumped modes, the laser is configured in a similar manner, except that an output coupler is omitted since the optical power is extracted from the laser cavity by the electro-optic switch itself. The same laser can be configured to operate in Q-switched and/or cavity-dumping modes as well as in hybrid modes (e.g., partial Q-switch, followed by cavity dumping, or even CW). In some embodiments, the laser can be used as, or inject laser light into, a regenerative solid-state amplifier, or a Raman laser, or can be also used to generate visible, ultra-violet, mid-infrared, and far-infrared (THz) radiation via nonlinear wavelength conversion processes. The various embodiments can use a power oscillator or seed-plus-amplifier MOPA configuration.

System and method for high-power, pulsed ring fiber oscillator

Apparatus and method for amplifying laser signals using segments of fibers of differing core diameters and/or differing cladding diameters to suppress amplified spontaneous emission and non-linear effects such as four-wave mixing (FWM), self-phase modulation, and stimulated Brillouin and/or Raman scattering (SBS/SRS). In some embodiments, different core sizes have different sideband spacings (spacing between the desired signal and wavelength-shifted lobes). Changing core sizes and providing phase mismatches prevent buildup of non-linear effects. Some embodiments further include a bandpass filter to remove signal other than the desired signal wavelength and/or a time gate to remove signal at times other than during the desired signal pulse. Some embodiments include photonic-crystal cores for the signal and/or photonic-crystal inner cladding for the pump and/or use reflector connector segments. Some embodiments include an inner glass cladding to confine the signal in the core and an outer glass cladding to confine pump light in the inner cladding.

Optical gain fiber having fiber segments with different-sized cores and associated method

An apparatus and method that provide optical isolation by permitting substantially all forward-propagating light into a delivery fiber from an optical amplifier and substantially preventing backward-traveling light from the delivery fiber entering the optical amplifier without the use of a conventional optical isolator. Eliminating the isolator improves efficiency and reduces cost. Some embodiments use a delivery fiber having a non-circular core in order to spread a single-mode signal into multiple modes such that any backward-propagating reflection is inhibited from reentering the single-mode amplifier. Some embodiments amplify an optical signal in a gain fiber having an output end, output the forward-propagating amplified signal as a high-brightness optical beam (having a first Rayleigh range) into a removable delivery fiber having a non-circular waveguide, output the amplified signal from a distal end of the delivery fiber, and, without the use of a non-linear optical isolator, inhibit backward-propagating light from re-entering the gain fiber.

System and method for a delivery fiber for isolation against back reflections

Apparatus and method for suppressing modal instabilities (MI) in fiber-amplifier systems. In some embodiments, thermal effects drive the MI process, and in some such embodiments, the present invention provides a plurality of options for mitigating these thermal effects. In some embodiments, the present invention provides a hybrid fiber with a smaller core in the initial length where the thermal loads are highest, followed by a larger-core fiber. In some embodiments the length of the smaller-core section is chosen to keep the core heat-per-unit-length of the second section below a critical value for the onset of MI. In some embodiments, the hybrid fiber of the present invention avoids modal instabilities while yielding almost the same performance as compared to conventional fibers with regard to minimizing fiber nonlinearities such as Stimulated Brillouin Scattering (SBS). In some embodiments, the hybrid fiber outputs a signal beam with at least 1 kW of power.

Fiber amplifier system for suppression of modal instabilities and method

Q-switched oscillator seed-source for MOPA laser illuminator method and apparatus

In some embodiments, the present invention provides an apparatus, method and use for improving and merging two existing techniques (core pumping and cladding pumping) to enable high-power fiber-laser systems having excellent beam quality while using large-core (LMA) step-index gain fibers at very high optical power, wherein the core pumping includes mixing a laser seed optical signal (having a signal wavelength) with optical core-pump light (having a core-pump wavelength that is near the signal wavelength) in a manner that matches the modes of the seed optical signal and the pump light. The combined core light is mode matched to the LMA gain fiber. The core-pump light is substantially all absorbed within a short distance from the entry end of the gain fiber and provides a strong pre-amplified signal for later cladding-pumped amplification. In some embodiments, the signal wavelength and the core-pump wavelength are within a single multiplet of a rare-earth dopant.

High beam quality and high average power from large-core-size optical-fiber amplifiers

A method and apparatus for mode-matching double-clad fibers. In some embodiments, a first fiber section that has a first core, wherein the first core has a first core diameter connects to a mode-field adaptor, wherein the mode-field adaptor includes a first portion having a central volume that has a substantially constant index-of-refraction radial profile and a diameter larger than the first core diameter, and a second portion that has a graded-index (GRIN) central volume, wherein the GRIN central volume has a central axis and a graded index-of-refraction radial profile having an index that gradually decreases at larger distances from its central axis and a length selected to focus light into the core of a second fiber wherein the second core has a diameter that is larger than the first core diameter, and wherein the second fiber section is double clad. Some embodiments are polarized.

Signal and pump mode-field adaptor for double-clad fibers and associated method

Method and apparatus for high-power, pulsed ring fiber oscillator

High-power laser system having delivery fiber with non-circular cross section for isolation against back reflections

Apparatus and method for amplifying laser signals using segments of fibers of differing core diameters and/or differing cladding diameters to suppress amplified spontaneous emission and non-linear effects such as four-wave mixing (FWM), self-phase modulation, and stimulated Brillouin and/or Raman scattering (SBS/SRS). In some embodiments, different core sizes have different sideband spacings (spacing between the desired signal and wavelength-shifted lobes). Changing core sizes and providing phase mismatches prevent buildup of non-linear effects. Some embodiments further include a bandpass filter to remove signal other than the desired signal wavelength and/or a time gate to remove signal at times other than during the desired signal pulse. Some embodiments include photonic-crystal structures to define the core for the signal and/or the inner cladding for the pump. Some embodiments include an inner glass cladding to confine the signal in the core and an outer glass cladding to confine pump light in the inner cladding.

Optical gain fiber having tapered segments of differing core sizes and associated method

An apparatus and process using a high-power, short-pulsed thulium laser to output infrared laser pulses delivered through an optical fiber, for cutting and ablating biological tissue. In some embodiments, the pulse length is shortened sufficiently to keep inside the stress-confined ablation region of operation. In some embodiments, the pulse is shortened to near the stress-confined ablation region of operation, while being slightly in the thermal-constrained region of operation. In some embodiments, the laser is coupled to a small low-OH optical fiber (&#x2dc;100 &#x3bc;m diameter). In some embodiments, the device has a pulse duration of about 100 ns for efficient ablation; however in some embodiments, this parameter is adjustable.

Multiple-mode device for high-power short-pulse laser ablation and CW cauterization of bodily tissues

Apparatus and method for generating controlled-linewidth laser-seed-signals for high-powered fiber-laser amplifier systems. In some embodiments, the natural chirp (frequency change of laser light over a short start-up time) of a DBR laser diode when driven by pulsed current is used to broaden the linewidth of the laser output, while adjusting the peak current and/or the pulse duration to obtain the desired linewidth.

Method and apparatus to suppress gain-switched spikes in fiber laser amplifier systems

An apparatus and process using a high-power, short-pulsed thulium laser to output infrared laser pulses delivered through an optical fiber, for cutting and ablating biological tissue. In some embodiments, the pulse length is shortened sufficiently to keep inside the stress-confined ablation region of operation. In some embodiments, the pulse is shortened to near the stress-confined ablation region of operation, while being slightly in the thermal-constrained region of operation. In some embodiments, the laser is coupled to a small low &#x2014;OH optical fiber (&#x2dc;100 &#x3bc;m diameter). In some embodiments, the device has a pulse duration of about 100 ns for efficient ablation; however in some embodiments, this parameter is adjustable.

Growing community of inventors

Woodinville, WA, United States of America

Matthias P Savage-Leuchs