Patents by Inventor Robert G. Waarts

Robert G. Waarts has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6021141
    Abstract: A harmonic generator laser system which features a distributed Bragg reflector (DBR) or distributed feedback (DFB) tunable diode laser coupled to a quasi-phase matched (QPM) waveguide of optically nonlinear material. Tuning of the DBR laser may be achieved either thermally or via current injection, or both, halving the wavelength of a red laser into the visible blue spectral band. Thermal tuning may provide a coarse tuning adjustment, while injected current may provide fine tuning accessible to a user. Separately or in combination with current tuning, a modulation signal may be applied to the DBR laser for achieving an intensity modulated or a pulsed output. In another embodiment, modulation may be achieved by frequency modulation of the laser. A very compact tunable blue laser is formed. In yet another embodiment a double clad fiber amplifier is disposed between the tunable laser and the waveguide.
    Type: Grant
    Filed: February 28, 1997
    Date of Patent: February 1, 2000
    Assignee: SDL, Inc.
    Inventors: Derek W. Nam, David F. Welch, Robert G. Waarts, Jo S. Major
  • Patent number: 5933271
    Abstract: Two approaches are provided for achieving an optical amplifier system capable of producing high peak power, high energy pulse outputs while suppressing scattering noise. The first approach relates to an optical amplifier system which has at least one laser diode pulsed or cw pumped double clad fiber amplifier utilized for receiving a high frequency modulated injected signal pulse of short duration from the laser diode, via the fiber core, for amplification by coupling pump light into the inner cladding of the fiber. The average signal power is sufficient to saturate the gain of the fiber so as to minimize significant onset and buildup of forward and backward scattering noise. The duty cycle of the injected signal source pulse is chosen to allow adequate gain recovery in the fiber amplifier between pulses.
    Type: Grant
    Filed: February 2, 1998
    Date of Patent: August 3, 1999
    Assignee: SDL, Inc.
    Inventors: Robert G. Waarts, Steven Sanders, David F. Welch
  • Patent number: 5912910
    Abstract: Laser diode pumped mid-IR wavelength systems 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.
    Type: Grant
    Filed: May 17, 1996
    Date of Patent: June 15, 1999
    Assignee: SDL, Inc.
    Inventors: Steven Sanders, Robert J. Lang, Robert G. Waarts
  • Patent number: 5892615
    Abstract: An optical fiber used as the active amplifying medium in a fiber laser is arranged to have a high insertion loss at an undesired frequency, while retaining a low insertion loss at a desired lasing frequency. In one embodiment, loss at a Raman-shifted frequency is introduced by using an optical fiber which has multiple claddings with an index profile that includes an elevated index region located away from the core, but within the evanescent coupling region of the core. A distributed loss, which can be enhanced by bending, is produced at the Raman frequency which effectively raises the threshold at which Raman scattering occurs in the fiber and therefore results in a frequency-selective fiber. In another embodiment, an absorbing layer is placed around the core region. The absorbing layer is chosen to have a sharp absorption edge so that it absorbs highly at the Raman-shifted wavelength, but minimally at the desired lasing wavelength.
    Type: Grant
    Filed: March 17, 1997
    Date of Patent: April 6, 1999
    Assignee: SDL, Inc.
    Inventors: Stephen G. Grubb, Raymond Zanoni, Robert G. Waarts, Jean-Luc Archambault
  • Patent number: 5875053
    Abstract: Several embodiments are described for induced electric field or E-field poling of QPM nonlinear crystal materials, such as LiNbO.sub.3, LiTaO.sub.3 and KTP, utilizing approaches which, for the most part, avoid the necessity of depositing or otherwise forming a series of spatially disposed conductive electrodes on one surface of the nonlinear crystal material. E-field poling is accomplished by applying a high voltage electric field in excess, for example, in the range of several kilovolts per cm to several 100 kilovolts per centimeter, at room temperature to provide inverted domains in a pattern of continuously alternating domains corresponding to the regions formed on the first z surface of the crystal. The employment of single, planar-applied liquid electrodes is preferred eliminating any necessity of forming and removing previously formed metal electrodes in the poling process.
    Type: Grant
    Filed: January 23, 1997
    Date of Patent: February 23, 1999
    Assignee: SDL, Inc.
    Inventors: Jonas Webjorn, Robert G. Waarts, Derek Nam, Donald R. Scifres
  • Patent number: 5867305
    Abstract: Two approaches are provided for achieving an optical amplifier system capable of producing high peak power, high energy pulse outputs while suppressing scattering noise. The first approach relates to an optical amplifier system which has at least one laser diode pulsed or cw pumped double clad fiber amplifier utilized for receiving a high frequency modulated injected signal pulse of short duration from the laser diode, via the fiber core, for amplification by coupling pump light into the inner cladding of the fiber. The average signal power is sufficient to saturate the gain of the fiber so as to minimize significant onset and buildup of forward and backward scattering noise. The duty cycle of the injected signal source pulse is chosen to allow adequate gain recovery in the fiber amplifier between pulses.
    Type: Grant
    Filed: January 19, 1996
    Date of Patent: February 2, 1999
    Assignee: SDL, Inc.
    Inventors: Robert G. Waarts, Steven Sanders, David F. Welch, Donals R. Scifres
  • Patent number: 5790576
    Abstract: Coherent light sources combining a semiconductor optical source with a light diverging region, such as a flared resonator type laser diode or flared amplifier type MOPA, with a single lens adapted to correct the astigmatism of the light beam emitted from the source is disclosed. The lens has an acircular cylindrical or toroidal first surface and an aspheric or binary diffractive second surface. The first surface has a curvature chosen to substantially equalize the lateral and transverse divergences of the astigmatic beam. Sources with an array of light diverging regions producing an array of astigmatic beams and a single astigmatism-correcting lens array aligned with the beams are also disclosed. The single beam source can be used in systems with frequency converting nonlinear optics. The array source can be stacked with other arrays to produce very high output powers with high brightness.
    Type: Grant
    Filed: June 26, 1996
    Date of Patent: August 4, 1998
    Assignee: SDL, Inc.
    Inventors: Robert G. Waarts, Robert J. Lang, Julian S. Osinski, Edmund L. Wolak, John Endriz
  • Patent number: 5677920
    Abstract: An upconversion fiber laser uses a pump source which may be another fiber laser, such as a high power, diode-laser-pumped, fiber laser. The upconversion fiber laser includes an optical fiber whose core region is doped with an active lasing ionic species capable when optically pumped of undergoing upconversion excitation, such as certain rare earth ionic species, and which is embedded in a cladding of the optical fiber. Use of a fiber pump laser can improve coupling of pump light into the optical fiber, thereby achieving higher pump intensities in the core region and improved upconversion efficiency. The upconversion fiber laser's resonant laser cavity is defined by feedback means which can include at least one reflective grating formed in the optical fiber, as well as a reflective end face of the optical fiber.
    Type: Grant
    Filed: December 14, 1995
    Date of Patent: October 14, 1997
    Assignee: SDL, Inc.
    Inventors: Robert G. Waarts, David F. Welch, Steven Sanders, Donald R. Scifres
  • Patent number: 5657153
    Abstract: In an optical transmission medium, such as a fiber amplifier, two optically distinguishable signals with complementary modulation are both inputted into the amplifying medium for encoding information, particularly a serial stream of digital data, or alternatively, redundant encoding of pulses. The gain profile in the medium is preferably maintained approximately constant at all times, so that whichever amplified signal is used as the primary information carrier, its output intensity will be substantially stable from pulse to pulse, independent of recent pulse history. The two complementary signals may have different orthogonal linear polarizations or wavelengths with the same stimulated emission cross-section, so that the population inversion profile stays constant, whichever signal happens to be on at a given moment.
    Type: Grant
    Filed: March 21, 1995
    Date of Patent: August 12, 1997
    Assignee: SDL, Inc.
    Inventors: John Endriz, David F. Welch, Robert G. Waarts, Steven Sanders, Donald R. Scifres
  • Patent number: 5654229
    Abstract: A method for providing an nonlinear, frequency converting optical QPM waveguide device by growing a first ferroelectric oxide film or layer on a second ferroelectric layer or medium wherein, in first and second embodiments, respectively, the second layer is initially provided with a periodic nonlinear coefficient pattern or a periodic pattern comprising a seed layer. During the growth of the first layer, the periodic pattern formed in the second layer, is replicated, transformed or induced into the first layer resulting in a plurality of substantially rectangular prismatic-shaped domains in the first layer having the periodic nonlinear coefficient pattern status based upon the periodic patterning of the second layer.
    Type: Grant
    Filed: April 26, 1995
    Date of Patent: August 5, 1997
    Assignee: Xerox Corporation
    Inventors: Florence E. Leplingard, John J. Kingston, Ross D. Bringans, David K. Fork, Robert G. Waarts, David F. Welch, Randall S. Geels
  • Patent number: 5644584
    Abstract: A harmonic generator laser system which features a distributed Bragg reflector (DBR) or distributed feedback (DFB) tunable diode laser coupled to a quasi-phasematched (QPM) waveguide of optically nonlinear material. Tuning of the DBR laser may be achieved either thermally or via current injection, or both, halving the wavelength of a red laser into the visible blue spectral band. Thermal tuning may provide a coarse tuning adjustment, while injected current may provide fine tuning accessible to a user. Separately or in combination with current tuning, a modulation signal may be applied to the DBR laser for achieving an intensity modulated or a pulsed output. In another embodiment, modulation may be achieved by frequency modulation of the laser. A very compact tunable blue laser is formed. In yet another embodiment a double clad fiber amplifier is disposed between the tunable laser and the waveguide.
    Type: Grant
    Filed: March 29, 1996
    Date of Patent: July 1, 1997
    Assignee: SDL, Inc.
    Inventors: Derek W. Nam, David F. Welch, Robert G. Waarts, Jo S. Major
  • Patent number: 5539571
    Abstract: An optical amplifier semiconductor device which is differentially pumped and a master oscillator power amplifier (MOPA) device employing such an amplifier. The amplifier allows the light propagating therein to diverge along at least part of its length, and may be a flared amplifier having a gain region that increases in width toward its output at a rate that equals or exceeds the divergence of the light. The amplifier is pumped with a current density at its input end which is smaller than the current density used to pump the output end for maintaining coherence of the beam to high power levels. Differential pumping may be both longitudinal and lateral within the amplifier. A single mode preamplifier section may be optically coupled to the input end of the amplifier. The amplifier input may have a width which is the same as or wider than that of the preamplifier output. The preamplifier may have a constant mode width or may be tapered to alter the divergence of the beams provided to the amplifier section.
    Type: Grant
    Filed: February 28, 1994
    Date of Patent: July 23, 1996
    Assignee: SDL, Inc.
    Inventors: David F. Welch, Donald R. Scifres, Robert G. Waarts, David G. Mehuys, Amos A. Hardy, Ross A. Parke
  • Patent number: 5530709
    Abstract: An upconversion fiber laser with a double-clad fiber is pumped with a laser-diode-based laser pump source, the inner cladding of the fiber forming a low transmission loss waveguide for the pump light. The central core of the fiber is doped with an active lasing ionic species capable of undergoing upconversion excitation, such as certain rare earth ionic species. The use of a double-clad fiber permits the use of high power, high brightness laser diodes, including those with broad emitting apertures, as well as high power diode laser pumped fiber lasers, as the pump source, thereby achieving higher pump intensities within the upconversion laser fiber and improved upconversion efficiency. Pump brightness can be further increased with multiple pump schemes which use multiple pump wavelengths in different absorption bands, multiple pump wavelengths within the same absorption band, pump light from pairs of cross-polarized sources, and pumping from both ends of the fiber.
    Type: Grant
    Filed: September 6, 1994
    Date of Patent: June 25, 1996
    Assignee: SDL, Inc.
    Inventors: Robert G. Waarts, David F. Welch, Steven Sanders, Donald R. Scifres
  • Patent number: 5440576
    Abstract: A phased array of flared amplifiers fed by phase adjusters and a power splitter produces a single high power beam when the flared amplifier sections are aligned and closely spaced. In one embodiment the array is excited by a DBR laser integrated into the same substrate as the flared amplifiers. In another embodiment the array is self-excited and forms a laser between an edge of the substrate common to the power splitter and an edge of the substrate common to the flared amplifier.
    Type: Grant
    Filed: April 18, 1994
    Date of Patent: August 8, 1995
    Assignee: SDL, Inc.
    Inventors: David F. Welch, Robert J. Lang, Julian S. Osinski, Kenneth M. Dzurko, David G. Mehuys, Robert G. Waarts
  • Patent number: 5384797
    Abstract: A monolithic multi-wavelength laser diode array having a composite active region of at least two dissimilar quantum well layers that are partially mixed in at least one of their constituent atomic species in at least one area of the active region. Different areas of the active region are characterized by different emission wavelengths determined by the degree of intermixing. An impurity free interdiffusion, such as vacancy enhanced interdiffusion, is used to provide the intermixing. Each area may have one or more waveguides and distributed Bragg reflector gratings tuned to the emission wavelength of the corresponding area of the active region. Each area or waveguide may also be separately pumped with an individually addressable current injection electrode. The laser output may be coupled into a ferroelectric frequency doubler integrally formed on the array substrate.
    Type: Grant
    Filed: September 21, 1992
    Date of Patent: January 24, 1995
    Assignees: SDL, Inc., Xerox Corporation
    Inventors: David F. Welch, Robert G. Waarts, Jo S. Major, Ross D. Bringans, David K. Fork, G. A. Neville Connell, Robert L. Thornton
  • Patent number: 5321718
    Abstract: A compact semiconductor laser light source providing short wavelength (ultraviolet, blue or green) coherent light by means of frequency doubling of red or infrared light from a high power diode heterostructure. The high power diode heterostructure is a MOPA device having a single mode laser oscillator followed by a multimode, preferably flared, optical power amplifier. A tunable configuration having an external rear reflector grating could also be used. A lens could be integrated with the MOPA to laterally collimate the light before it is emitted. Straight or curved, surface emitting gratings could also be incorporated. An astigmatism-correcting lens system having at least one cylindrical lens surface is disposed in the path of the output from the MOPA to provide a beam with substantially equal lateral and transverse beam width dimensions and beam divergence angles. A nonlinear optical crystal or waveguide is placed in the path of the astigmatism-free symmetrized beam to double the frequency of the light.
    Type: Grant
    Filed: January 28, 1993
    Date of Patent: June 14, 1994
    Assignee: SDL, Inc.
    Inventors: Robert G. Waarts, David F. Welch, Donald R. Scifres, Robert J. Lang, Derek W. Nam
  • Patent number: 5255332
    Abstract: An optical crossbar switch matrix for use in switching optical signals from a first set of optical fibers to a second set of optical fibers, in any order, which is characterized by having a matrix of rows and columns of diffraction gratings formed in a semiconductor heterostructure. Each grating is independently biased with either a forward or reverse bias voltage to switch the grating between a reflective state and a transmissive state. The gratings are oriented at an angle relative to the rows and columns so that when the Bragg condition for the light received from an optical film is met, a portion of the light is diffracted from the row in which it is propagating into a column toward another optical fiber. The heterostructure may include optical amplifiers to restore the optical signal to its original power level. Beam expanding, collimating and focussing optics may also be integrated into the heterostructure.
    Type: Grant
    Filed: July 16, 1992
    Date of Patent: October 19, 1993
    Assignee: SDL, Inc.
    Inventors: David F. Welch, Donald R. Scifres, Robert G. Waarts, Amos A. Hardy, David G. Mehuys, Stephen O'Brien
  • Patent number: 5231642
    Abstract: A semiconductor laser that includes at least one grating reflector with a grating period selected to diffract at a nonperpendicular angle within the plane of the laser waveguide. This allows dispersal of laser light, eliminating filamentary multimode operation of broad area lasers. In one embodiment, the grating reflector couples light between a single transverse mode waveguide portion of the optical cavity and a second, broad area, portion that is not collinear with the single mode waveguide. In another embodiment, the cavity favors a ring mode of oscillation. One or more grating reflectors form part of the feedback mechanism which forms a resonant optical cavity with noncollinear portions. Other reflectors in the feedback mechanism include facet reflectors which can be cleaved or ion milled, or semiconductor material refractive index boundaries. Laser embodiments with two or more grating reflectors can be independently tuned to provide a high rate of amplitude modulation.
    Type: Grant
    Filed: May 8, 1992
    Date of Patent: July 27, 1993
    Assignee: Spectra Diode Laboratories, Inc.
    Inventors: Donald R. Scifres, Kenneth M. Dzurko, Robert G. Waarts, David F. Welch, Amos Hardy, Stephen O'Brien
  • Patent number: 5185752
    Abstract: Arrangements for efficiently coupling light between a laser diode and a second-harmonic generator which feature external resonant cavities that include a feedback grating fabricated on the second-harmonic generator. The feedback grating reflects light of a first frequency that matches the frequency doubling band of the second-harmonic generator, thereby establishing stable laser oscillation at that first frequency. Preferably, the second-harmonic generator has a periodically-poled waveguide formed in the surface of the nonlinear material body. The laser diode may be butted against the harmonic generator or coupling optics may be positioned between the two. In one arrangement, a polarizer is placed in the resonant cavity, either between an external back reflector and the back facet of the laser diode or between the antireflection coated front facet of the laser diode and the harmonic generator, to provide loss to the TE polarization mode and enhance oscillation in the TM polarization mode.
    Type: Grant
    Filed: February 18, 1992
    Date of Patent: February 9, 1993
    Assignee: Spectra Diode Laboratories, Inc.
    Inventors: David F. Welch, Robert G. Waarts
  • Patent number: RE35215
    Abstract: A compact semiconductor laser light source providing short wavelength (ultraviolet, blue or green) coherent light by means of frequency doubling of red or infrared light from a high power diode heterostructure. The high power diode heterostructure is a MOPA device having a single mode laser oscillator followed by a multimode, preferably flared, optical power amplifier. A tunable configuration having an external rear reflector grating could also be used. A lens could be integrated with the MOPA to laterally collimate the light before it is emitted. Straight or curved, surface emitting gratings could also be incorporated. An astigmatism-correcting lens system having at least one cylindrical lens surface is disposed in the path of the output from the MOPA to provide a beam with substantially equal lateral and transverse beam width dimensions and beam divergence angles. A nonlinear optical crystal or waveguide is placed in the path of the astigmatism-free symmetrized beam to double the frequency of the light.
    Type: Grant
    Filed: September 16, 1994
    Date of Patent: April 23, 1996
    Assignee: SDL, Inc.
    Inventors: Robert G. Waarts, David F. Welch, Donald R. Scifres, Robert J. Lang, Derek W. Nam