Abstract: Optical pumping arrangements are provided for the broadband or multiple wavelength pumping of optical sources. Sources may be based on Raman gain media for amplification. Broadband amplification is provided by using a laser source operating in coherence collapse. Such a source may make use of an optical generator and an output coupler which are sufficiently far apart from one another as to ensure coherence collapse.

Abstract: Power scaling by multiplexing multiple fiber gain sources with different wave-lengths is useful in printing applications requiring higher optical powers to perform the printing function, such as through thermal inducement in thermal ablation, thermal fusion, thermal diffusion or thermal transfer. A marking system is disclosed using a plurality of laser sources operating at different wavelengths with their respective outputs coupled into a respective single mode fiber. At least one WDM combiner is coupled to receive and combine the laser source outputs into a single output. The combined power single output provides sufficient power intensity to induce thermal marking on a marking medium.

Abstract: Optical pumping arrangements are provided for the broadband or multiple wavelength pumping of optical sources. Sources may be based on Raman gain media and may use multiple output couplers to couple out different wavelength ranges. Cascaded Raman resonator (CRR) configurations may also be used. Overlapping resonators at different wavelengths may be configured to share gain media, and may have separate portions in separate optical paths. Attenuation filters may also be used that are matched to the gain profile of a gain medium, to flatten the gain spectrum and allow equalization of gain to different output wavelengths. In one embodiment, polarization maintaining fiber is used to develop resonant conditions at different wavelengths in different polarization states. Wideband output gratings may be substituted for narrowband gratings to provide CRR configurations with a broader output band. Broadband amplification may also be provided by using a laser source operating in coherence collapse.

Abstract: A pump source for rare earth and Raman amplifiers or for distributed amplification uses two or more light sources to generate two source beams that are combined by a beam combiner to form the output pump beam. In accordance with one embodiment, the light sources are a diode laser array having be two or more monolithic laser stripes providing dual output beams having substantially the same polarization, such as the TE mode. One of the polarized due outputs is rotated 90° and both beams are applied to a birefringent crystal that combines the beams for insertion into an optical fiber or into a rare earth doped fiber or into a fiber capable of Raman amplification via SRS. The power output of each polarization in the combined beam can be measured and used to drive a feedback circuit that controls the current provided to each diode in order to maintain the power in the two polarization components of the output beam equal.

Abstract: A multistage optical fiber amplifier (OFA) system is designed to be upgraded with the addition of pump power when signal capacity of an optical communication link is correspondingly increased. The system includes a gain flattening filter (GFF) that remains valid when the system is upgraded because of the system design. Also disclosed are ways to enhance the GFF as well as control the channel signal gain tilt as well as adjust the external gain uniformity to be the same for an assembly line of OFA systems.

Abstract: A strain sensor is disclosed for example for use in a Bragg fiber grating, in which piezoelectric actuators are arranged to compress or extend the fiber, and a capacitance micrometer for measuring the strain on the fiber in a servo loop with the actuators to provide a tunable grating in which the selected wavelength is a unique and linear function of the control command parameter. The micrometer electrodes can be placed on opposing faces of ferrules on the fiber, or capacitance between a coating directly on the fiber and a reference electrode can be used.

Abstract: A multistage optical amplifier pumping system with built-in redundant reliability for lightwave communication system provides plural levels of redundancy. A first level of redundancy deals with redundancy in the form of plural primary laser diode sources for pumping a single fiber laser pump source. A second level of redundancy deals with redundancy of a plurality of fiber laser pump sources for pumping a plurality of serially connected injection signal fiber amplifiers forming the multistage amplifier system. If one of fiber pump sources should fail, increased pumping power is available from the remaining fiber pump sources via their respectively connected amplifier stages. A third level of redundancy deals with redundancy in the employment of multiple single mode laser emitters on the same chip or bar sufficiently segmented and/or electrical isolated so as not to interfere with operation of or cause failure to adjacent or neighboring emitters on the same chip or bar.

Abstract: An optical fiber amplifier has an amplification stage that uses an optical fiber pumped with pump energy of a first wavelength that oscillates through the gain medium. In one embodiment, the pumping is essentially a cavity resonator that is coupled to either end of the optical fiber such that oscillating pump energy is directed into one end of the fiber and out the other, as it reflects back and forth between the ends of the cavity. Highly reflective gratings are used to maintain the oscillation of the pump energy, and a pump energy source, such as pumped doped optical fiber, is coupled to at least one of the gratings. In another embodiment, the pump source comprises multiple reflectors that are employed at each end of the fiber, and independent pump sources each having a slightly different wavelength within the absorption spectrum of the amplifier are coupled together, such that two pump wavelengths are simultaneously oscillated through the gain medium.

Abstract: A fiber laser uses a mechanism to prevent a thermally induced shift of the gain spectrum to a range that causes the laser to become destabilized when operated at a first signal wavelength. By establishing a nominal gain spectrum that is further from the undesired range than in a conventional laser, a gain spectrum shift does not reach the undesired wavelength range. This may be accomplished by decreasing the reflectivity of a resonant cavity of the laser, such as by angling the reflective end of the cavity. It may also be accomplished by increasing the population inversion of the laser. Using a pump energy reflector to prevent pump energy from exiting the inner cladding of a double-clad version of the laser the fiber may increase population inversion. The fiber length may also be shortened or the diameter of the inner cladding reduced to increase the population inversion before a laser output is achieved.

Abstract: A high power laser optical amplifier system for material processing comprises multiple stage fiber amplifiers with rejection of propagating ASE buildup in and between the amplifier stages as well as elimination of SBS noise providing output powers in the range of about 10 &mgr;J to about 100 &mgr;J or more. The system is driven with a time varying drive signal from a modulated semiconductor laser signal source to produce an optical output allowing modification of the material while controlling its thermal sensitivity by varying pulse shapes or pulse widths supplied at a desire repetition rate via modulation of a semiconductor laser signal source to the system to precisely control the applied power application of the beam relative to the thermal sensitivity of the material to be processed. The high power fiber amplifier system has particular utility in high power applications requiring process treatment of surfaces, such as polymeric, organic, ceramic and metal surfaces, e.g.

Abstract: A double-clad optical fiber has an inner cladding that has a torsional stress induced within it during manufacture. By rotating the fiber preform before curing of the inner cladding layer, a physical stress may be permanently imparted to the inner cladding that interacts with pump energy within the inner cladding layer to encourage mode mixing. As the cladding modes are disturbed by the stresses in the fiber, they are redirected so that the light in them intersects the core.

Abstract: A high power laser optical amplifier system for material processing comprises multiple stage fiber amplifiers with rejection of propagating ASE buildup in and between the amplifier stages as well as elimination of SBS noise providing output powers in the range of about 10 &mgr;J to about 100 &mgr;J or more. The system is driven with a time varying drive signal from a modulated semiconductor laser signal source to produce an optical output allowing modification of the material while controlling its thermal sensitivity by varying pulse shapes or pulse widths supplied at a desire repetition rate via modulation of a semiconductor laser signal source to the system to precisely control the applied power application of the beam relative to the thermal sensitivity of the material to be processed. The high power fiber amplifier system has particular utility in high power applications requiring process treatment of surfaces, such as polymeric, organic, ceramic and metal surfaces, e.g.

Abstract: The effectiveness of reflected light to stabilize the operational characteristics of a semiconductor diode laser varies with the polarization orientation of the reflected light. Stabilization failure can occur if the polarization orientation of the reflected light is orthogonal to the polarization of the light emitted by the laser source. The use of multiple reflectors can reduce the probability of stabilization failure by arranging the reflectors to return to the laser source portions of light having polarization orientations that are statistically independent with respect to each other.

Abstract: Laser diode pumped mid-IR wavelength sources include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Abstract: A frequency conversion system includes at least one source providing a first near-IR wavelength output including a gain medium for providing high power amplification, such as double clad fiber amplifier, a double clad fiber laser or a semiconductor tapered amplifier to enhance the power output level of the near-IR wavelength output. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Ra-man/Brillouin amplifier or oscillator between the high power source and the NFM device.

Abstract: A fiber laser or fiber amplifier uses resonant pumping of the gain medium by providing a pump resonator that establishes a resonator cavity at the pump wavelength which includes the pumped gain medium. The pump resonator may be of a distributed feedback (DFB) or a distributed Bragg reflector (DBR) type construction, and may be combined with signal reflection apparatus of either DFB or DBR type construction that provides oscillation of the desired laser output wavelength. If used without a signal reflection apparatus, the invention may be operated as a resonant pumped fiber amplifier. A resonant pumped laser may use a wavelength stabilized pump source to maximize pumping efficiency, the stabilization being provided by optical feedback.

Abstract: A frequency conversion system comprises first and second gain sources providing first and second frequency radiation outputs where the second gain source receives as input the output of the first gain source and, further, the second gain source comprises a Raman or Brillouin gain fiber for wave shifting a portion of the radiation of the first frequency output into second frequency radiation output to provided a combined output of first and second frequencies. Powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Abstract: An optical amplifier makes use of a co-propagating fiber amplifier stage and a counter propagating fiber amplifier stage. One of the stages is preferably a low noise stage, while the other is a high gain stage, typically the output stage. The low noise stage may have a small core fiber while the high gain stage has a large core fiber. Pumping energy is introduced into the amplifier by coupling a plurality of laser sources in the same wavelength range using a narrow channel wavelength division multiplexer coupler. In each stage of the amplifier, some portion of the pump energy is transferred from the pumping wavelength to the signal wavelength. In a single polarization optical signal generator embodiment, the optical signal is developed in a distributed Bragg reflector oscillator having an output Bragg grating embedded in a polarization perserving fiber. A polarization controller is used at the amplifier output to restore the single polarization which is developed in the oscillator.

Abstract: Power scaling by multiplexing multiple fiber gain sources with different wavelengths, pulsing or polarization modes of operation is achieved through multiplex combining of the multiple fiber gain sources to provide high power outputs, such as ranging from tens of watts to hundreds of watts, provided on a single mode or multimode fiber.

Abstract: A fiber laser or fiber amplifier uses resonant pumping of the gain medium by providing a pump resonator that establishes a resonator cavity at the pump wavelength which includes the pumped gain medium. The pump resonator may be of a distributed feedback (DFB) or a distributed Bragg reflector (DBR) type construction, and may be combined with signal reflection apparatus of either DFB or DBR type construction that provides oscillation of the desired laser output wavelength. If used without a signal reflection apparatus, the invention may be operated as a resonant pumped fiber amplifier. Multiple resonators may also be pumped by a single pump source by locating each in a different branch of a multiple branch directional coupler. If the resonators are constructed to couple their outputs away from the coupler, a plurality of different laser outputs each having a different wavelength and equal output powers is provided.