Patents by Inventor Ralph H. Johnson
Ralph H. Johnson 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).
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Patent number: 7346090Abstract: A VCSEL with nearly planar intracavity contact. A bottom DBR mirror is formed on a substrate. A first conduction layer region is formed on the bottom DBR mirror. An active layer, including quantum wells, is on the first conduction layer region. A trench is formed into the active layer region. The trench is formed in a wagon wheel configuration with spokes providing mechanical support for the active layer region. The trench is etched approximately to the first conduction layer region. Proton implants are provided in the wagon wheel and configured to render the spokes of the wagon wheel insulating. A nearly planar electrical contact is formed as an intracavity contact for connecting the bottom of the active region to a power supply. The nearly planar electrical contact is formed in and about the trench.Type: GrantFiled: October 30, 2006Date of Patent: March 18, 2008Assignee: Finisar CorporationInventors: Ralph H. Johnson, R. Scott Penner, James Robert Biard
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Publication number: 20080023688Abstract: Semiconductor devices such as VCSELs, SELs, LEDs, and HBTs are manufactured to have a wide bandgap material near a narrow bandgap material. Electron injection is improved by an intermediate structure positioned between the wide bandgap material and the narrow bandgap material. The intermediate structure is an inflection, such as a plateau, in the ramping of the composition between the wide bandgap material and the narrow bandgap material. The intermediate structure is highly doped and has a composition with a desired low electron affinity. The injection structure can be used on the p-side of a device with a p-doped intermediate structure at high hole affinity.Type: ApplicationFiled: April 16, 2007Publication date: January 31, 2008Applicant: FINISAR CORPORATIONInventor: Ralph H. Johnson
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Patent number: 7308011Abstract: A single mode VCSEL including a substrate having a lower surface and an upper surface, a bottom electrical contact disposed along the lower surface of the substrate, a lower mirror portion disposed upon the upper surface of the substrate, an active region disposed upon the lower mirror portion, an upper mirror portion disposed upon the active region, an equipotential layer disposed upon the upper mirror portion, an insulating layer interposed between the upper mirror portion and the equipotential layer and adapted to form an aperture therebetween, and an upper contact portion disposed upon the equipotential layer outside the perimeter of the aperture.Type: GrantFiled: July 11, 2003Date of Patent: December 11, 2007Assignee: Finisar CorporationInventors: Ralph H. Johnson, Gilberto Morales
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Patent number: 7286585Abstract: A laser system having migration enhanced epitaxy grown substantially flat layers proximate to quantum wells of an active region. The flat layers may be grown at low temperature. This growth may result in flatter interfaces in the nitrogen containing quantum wells within the active region as well as lower trap densities in adjacent material. This may achieve a reduced trap density as well as reduced segregation resulting in a spectral luminescence profile revealing a single narrow peak with a high level of photoluminescence.Type: GrantFiled: March 14, 2005Date of Patent: October 23, 2007Assignee: Finisar CorporationInventor: Ralph H. Johnson
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Patent number: 7257143Abstract: Multi-component barrier layers include formation of a GaAs layer and at least one adjacent GaAsN layer. The resulting multi-component barrier layer shape can provide enhanced (extended) offset for capture of holes and enhanced electrons. Other benefits include: a small amount of strain compensation; poorer spatial overlap of higher confined states reducing parasitics at high bias, with some small effect on the lowest confined states. Quantum wells and associated barriers layers can be grown with combinations of gallium, (Ga), arsenic, (As), nitrogen (N), aluminum (Al), antimony (Sb), phosphorous (P) and/or indium (In) placed within or about a typical GaAs substrate to achieve long wavelength VCSEL performance, e.g., with wavelengths over 1200 nm. Layers of strained quantum well material can also be supported by mechanical stabilizers.Type: GrantFiled: October 1, 2004Date of Patent: August 14, 2007Assignee: Finisar CorporationInventor: Ralph H. Johnson
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Patent number: 7255746Abstract: MBE nitrogen sources of dimethylhydrazine, tertiarybutlyhydrazine, nitrogentrifloride, and NHx radicals. Those nitrogen sources are beneficial in forming nitrogen-containing materials on crystalline subtrates using MBE. Semiconductor lasers in general, and VCSEL in particular, that have nitrogen-containing layers can be formed using such nitrogen sources.Type: GrantFiled: September 4, 2002Date of Patent: August 14, 2007Assignee: Finisar CorporationInventors: Ralph H. Johnson, Jin K. Kim, James K. Guenter
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Patent number: 7251264Abstract: This disclosure concerns devices such as DBRs, one example of which includes at least one first mirror layers having an oxidized region extending from an edge of the DBR to an oxide termination edge that is situated greater than a first distance from the edge of the DBR. The DBR also includes at least one second mirror layer having an oxidized region extending from the edge of the DBR to an oxide termination edge that is situated less than a second distance from the edge of the DBR, such that the first distance is greater than the second distance. Additionally, a first mirror layer includes an oxidizable material at a concentration that is higher than the concentration of the oxidizable material in any of the second mirror layers. Finally, a first mirror layer is doped with an impurity at a higher level than one of the second mirror layers.Type: GrantFiled: April 29, 2005Date of Patent: July 31, 2007Assignee: Finisar CorporationInventors: Ralph H. Johnson, Klein L. Johnson, Jimmy A. Tatum, James K. Guenter, James R. Biard, Robert A. Hawthorne, III
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Patent number: 7221691Abstract: A system and method for providing a single mode VCSEL (vertical cavity surface emitting laser). A lower mirror is formed on a substrate. An active region including one or more quantum wells is formed over the lower mirror. The upper mirror formed over the active region can include multiple layers and may be formed to be have substantially isotropic conductivity. The layers in the upper mirror can include a lightly doped DBR layer, a heavily doped second layer including an isolation region, and a third heavily doped DBR layer. The active region may include conduction layers, which may be periodically doped, to improve conductivity and reduce free carrier absorption.Type: GrantFiled: July 10, 2003Date of Patent: May 22, 2007Assignee: Finisar CorporationInventors: Ralph H. Johnson, Gilberto Morales
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Patent number: 7167496Abstract: In order to achieve a long wavelength, 1.3 micron or above, VCSEL or other semiconductor laser, layers of strained quantum well material are supported by mechanical stabilizers which are nearly lattice matched with the GaAs substrate, or lattice mismatched in the opposite direction from the quantum well material; to allow the use of ordinary deposition materials and procedures. By interspersing thin, unstrained layers of e.g. gallium arsenide in the quantum well between the strained layers of e.g. InGaAs, the GaAs layers act as mechanical stabilizers keeping the InGaAs layers thin enough to prevent lattice relaxation of the InGaAs quantum well material. Through selection of the thickness and width of the mechanical stabilizers and strained quantum well layers in the quantum well, 1.3 micron and above wavelength lasing is achieved with use of high efficiency AlGaAs mirrors and standard gallium arsenide substrates.Type: GrantFiled: August 4, 2003Date of Patent: January 23, 2007Assignee: Finisar CorporationInventor: Ralph H. Johnson
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Patent number: 7167495Abstract: Incorporation of a GaAs “Extended lower barrier” in between quantum wells using nitrogen and confining layers using aluminum. Not to be confused with barrier layers used in quantum wells, the extended lower barrier is formed between the active region a nd the outer/confining layers where N and Al are respectively used. N and Al can be separated in the case where, for example, AlGaAs is being used in the confining layers and any nitrogen containing material is being used in the active region. Aluminum and Nitrogen when allowed to combine can cause deep traps and resultant non-radiative recombination, therefore N and Al pairing should be prevented. The GaAs extended barrier layer can provide a protective measure against such combination.Type: GrantFiled: October 1, 2004Date of Patent: January 23, 2007Assignee: Finisar CorporationInventor: Ralph H. Johnson
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Patent number: 7110427Abstract: The invention is generally concerned with vertical cavity surface emitting lasers. In one example, the vertical cavity surface emitting laser includes, among other things, an upper mirror structure having a metal contact, a top mirror above the metal contact, and a semiconductive top DBR having an insulation region, wherein the top DBR is no more than 3.5 microns thick and is disposed below the metal contact. Thus, the top DBR is sufficiently thick as to enable adequate current spreading, but thin enough to enable fabrication of an isolation region using relatively low energy ion implantation or relatively shallow etching.Type: GrantFiled: September 3, 2004Date of Patent: September 19, 2006Assignee: Finisar CorporationInventors: Ralph H. Johnson, Tzu-Yu Wang
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Patent number: 7095770Abstract: Quantum wells and associated barriers layers can be grown to include nitrogen (N), aluminum (Al), antimony (Sb), phosphorous (P) and/or indium (In) placed within or about a typical GaAs substrate to achieve long wavelength VCSEL performance, e.g., within the 1260 to 1650 nm range. In accordance with features of the present invention, a vertical cavity surface emitting laser (VCSEL) can include at least one quantum well comprised of InGaAsSbN; barrier layers sandwiching said at least one quantum well; and confinement layers sandwiching said barrier layers. Confinement and barrier layers can comprise AlGaAs. Barrier layer, in the alternative, can also comprise GaAsP. Nitrogen can be placed in the quantum wells. Quantum wells can be developed up to and including 50 ? in thickness. Quantum wells can also be developed with a depth of at least 40 meV.Type: GrantFiled: December 20, 2001Date of Patent: August 22, 2006Assignee: Finisar CorporationInventor: Ralph H. Johnson
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Patent number: 7065124Abstract: A VCSEL having an N-type Bragg mirror with alternating layers of high bandgap (low index) and low bandgap (high index) layers of AlGaAs. The layers may be separated by a step change of Al composition followed by a graded region, and vice versa for the next layer, in the N-type mirror to result in a lower and more linear series resistance. Also, an N-type spacer layer may be adjacent to an active region of quantum wells. There may be a similar step in a change of Al composition from the nearest layer of the N-type mirror to the N-type spacer formed from a lower bandgap direct AlGaAs layer to provide lower free carrier absorption. With electron affinity engineering, a minority carrier hole barrier may be inserted adjacent to the quantum wells to improve hole confinement at high current density and high temperature.Type: GrantFiled: January 29, 2004Date of Patent: June 20, 2006Assignee: FinLsar CorporationInventors: James R. Biard, Ralph H. Johnson, Klein L. Johnson
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Patent number: 7061945Abstract: A vertical cavity surface emitting laser (VCSEL) in which a higher order lasing mode produces a Gaussian-like single mode far field beam intensity pattern. Such a VCSEL includes a protective surface deposition on a VCSEL structure, and phase filter elements on the surface deposition. The surface deposition and the phase filter elements implement an optical phase filter that induces optical path difference such that a single mode far field beam intensity pattern results when the VCSEL operates in a higher order lasing mode. The VCSEL can include structures that enhance a selected higher-order operating mode and/or that suppress unwanted operating modes.Type: GrantFiled: May 13, 2003Date of Patent: June 13, 2006Assignee: Finisar CorporationInventors: James A. Cox, Ralph H. Johnson, James K. Guenter, Robert Biard, Klein Johnson
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Patent number: 7058112Abstract: Quantum wells and associated barriers layers can be grown to include nitrogen (N), aluminum (Al), antimony (Sb), phosphorous (P) and/or indium (In) placed within or about a typical GaAs substrate to achieve long wavelength VCSEL performance, e.g., within the 1260 to 1650 nm range. In accordance with features of the present invention, a vertical cavity surface emitting laser (VCSEL), can include at least one quantum well comprised of GaAsSb; barrier layers sandwiching said at least one quantum well; and confinement layers sandwiching said barrier layers. Barrier and confinement layers can comprise of AlGaAs. Barrier layers can also be comprised of GaAsP. Nitrogen can be placed in quantum wells. Quantum wells can be developed up to and including 50 ? in thickness. Quantum wells can also be developed with a depth of at least 40 meV.Type: GrantFiled: December 27, 2001Date of Patent: June 6, 2006Assignee: Finisar CorporationInventor: Ralph H. Johnson
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Patent number: 7031363Abstract: A process for making a laser structure. The process is for the fabrication of a laser device such a vertical cavity surface emitting laser (VCSEL). The structures made involve dielectric and spin-on material planarization over wide and narrow trenches, coplanar contacts, non-coplanar contacts, thick and thin pad dielectric, air bridges and wafer thinning.Type: GrantFiled: October 29, 2003Date of Patent: April 18, 2006Assignee: Finisar CorporationInventors: James R. Biard, Klein L. Johnson, Ralph H. Johnson, Gyoungwon Park, Tzu-Yu Wang
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Patent number: 7023896Abstract: An active region of a VCSEL at one (i.e., n doped) end having an expanded effectively undoped region, and another (i.e., p doped) end having a significantly doped region up to or even including a portion of the active region. A previous way had heavy doping of the n and p doped regions up to the active region, at least close to it or even partially into it.Type: GrantFiled: January 24, 2003Date of Patent: April 4, 2006Assignee: Finisar CorporationInventor: Ralph H. Johnson
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Patent number: 7009224Abstract: A metamorphic device including a substrate structure upon which a semiconductor device can be formed. In the metamorphic device, a buffer layer matching a substrate lattice constant is formed at normal growth temperatures and a thin grading layer which grades past the desired lattice constant is configured at a low temperature. A reverse grading layer grades the lattice constant back to match a desired lattice constant. Thereafter, a thick layer is formed thereon, based on the desired lattice constant. Annealing can then occur to isolate dislocated material in at least the grading layer and the reverse grading layer. Thereon a strained layer superlattice is created upon which a high-speed photodiode or other semiconductor device can be formed.Type: GrantFiled: April 14, 2003Date of Patent: March 7, 2006Assignee: Finisar CorporationInventors: Ralph H. Johnson, James K. Guenter, James R. Biard
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Patent number: 6990135Abstract: An oxide-confined VCSELs having a distributed Bragg reflector with a heavily doped high Al content oxide aperture forming layer disposed between a low Al content first layer and a medium Al content second layer. Between the first layer and the oxide aperture forming layer there may be a thin transition region wherein the Al content changes from a higher Al content to a lower Al content. In some embodiments, the Al concentration from the oxide aperture forming layer to the second layer may occur in a step. The oxide aperture forming layer may be disposed at or near a null or a node of the electric field produced by resonant laser light. During the oxidization of the oxide aperture forming layer, all or some of the other aluminum bearing DBR layers may also become oxidized, but to a substantially lesser degree. The junction between the oxidized portion and un-oxidized portion of these layers is believed to reduce the stability and/or reliability of the device.Type: GrantFiled: October 28, 2002Date of Patent: January 24, 2006Assignee: Finisar CorporationInventors: Ralph H. Johnson, Klein L. Johnson, Jimmy A. Tatum, James K. Guenter, James R. Biard, Robert A. Hawthorne, III
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Patent number: 6975660Abstract: Quantum wells and associated barriers layers can be grown to include nitrogen (N), aluminum (Al), antimony (Sb), phosphorous (P) and/or indium (In) placed within or about a typical GaAs substrate to achieve long wavelength VCSEL performance, e.g., within the 1260 to 1650 nm range. In accordance with features of the present invention, a vertical cavity surface emitting laser (VCSEL), can include at least one quantum well comprised of InGaAsSb; barrier layers sandwiching said at least one quantum well; and confinement layers sandwiching said barrier layers. A vertical cavity surface emitting laser (VCSEL), can also include at least one quantum well comprised of InGaAsSbN. Barrier layers can be comprised of GaAsN, GaAsP, or AlGaAs. Confinement layers can be comprised of AlGaAs. Quantum wells can include N. Quantum wells can be developed up to and including 50 ? in thickness. Quantum wells can also be developed with a depth of at least 40 meV.Type: GrantFiled: December 27, 2001Date of Patent: December 13, 2005Assignee: Finisar CorporationInventor: Ralph H. Johnson