WO2001035506A1 - Commande de la repartition du courant dans des diodes lasers a semi-conducteurs - Google Patents

Commande de la repartition du courant dans des diodes lasers a semi-conducteurs Download PDF

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Publication number
WO2001035506A1
WO2001035506A1 PCT/US2000/031048 US0031048W WO0135506A1 WO 2001035506 A1 WO2001035506 A1 WO 2001035506A1 US 0031048 W US0031048 W US 0031048W WO 0135506 A1 WO0135506 A1 WO 0135506A1
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WO
WIPO (PCT)
Prior art keywords
active layer
layer
current
semiconductor laser
laser diode
Prior art date
Application number
PCT/US2000/031048
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English (en)
Other versions
WO2001035506A9 (fr
Inventor
John C. Connolly
Louis A. Dimarco
Original Assignee
Princeton Lightwave, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Princeton Lightwave, Inc. filed Critical Princeton Lightwave, Inc.
Priority to EP00980351A priority Critical patent/EP1247316A4/fr
Priority to JP2001537143A priority patent/JP2003515250A/ja
Priority to AU17626/01A priority patent/AU1762601A/en
Priority to CA002388858A priority patent/CA2388858A1/fr
Publication of WO2001035506A1 publication Critical patent/WO2001035506A1/fr
Publication of WO2001035506A9 publication Critical patent/WO2001035506A9/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/2054—Methods of obtaining the confinement
    • H01S5/2059—Methods of obtaining the confinement by means of particular conductivity zones, e.g. obtained by particle bombardment or diffusion
    • H01S5/2063—Methods of obtaining the confinement by means of particular conductivity zones, e.g. obtained by particle bombardment or diffusion obtained by particle bombardment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
    • H01S5/22—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers having a ridge or stripe structure

Definitions

  • the present invention relates to controlling the lateral extent of a region of a semiconductor laser diode that is exposed to a gain current, and specifically to controlling such lateral extent in a ridge waveguide semiconductor laser diode adapted to support selected lateral modes of the emitted laser light.
  • Typical semiconductor lasers such as laser diodes are formed by a body of semiconductor material having a thin, active region formed between cladding layers and contact regions of opposite polarity.
  • a waveguide is formed in the structure by defining a stripe for light guiding and for current injection. Light is generated in the active region when the stripe region is subject to a current flow between the positive and negative contact regions. Cladding and confinement regions, among others, are placed between the contacts and the active region for guiding and confining the light along the thickness of the layers. The various regions typically are formed as substantially parallel thin layers grown epitaxially.
  • the current is greater than the threshold current for the active waveguide, amplified light is generated. In general, the greater the current flowing into the active waveguide, the more light is generated.
  • the active regions can be shaped like a thin layer having a specified thickness, length and width.
  • the oscillation of the electric and magnetic fields of the light waves are restricted to specific modes, depending on the dimensions of the active layer.
  • the longitudinal mode of the light, along the direction of propagation, is determined by the longitudinal length of the active layer forming the laser cavity.
  • the thickness of the active layer restricts oscillation of the light waves in the transverse direction, perpendicular to the plane of the layers along which light propagates. By appropriately sizing the thickness of the layer, oscillations can be restricted to the fundamental mode or to other desired modes of the light.
  • the modes are not limited by the size of the active layer, but rather by the width of the stripe and of the current flow region. More than one mode can thus co-exist simultaneously within the active layer.
  • the light emitted may include more than one optical mode in the lateral direction, as described above.
  • the multi mode light emitted from this type of diode is thus of limited use, because it is formed by a complex pattern of bright and dark areas.
  • Many applications require laser light that has a far field pattern consisting of a single bright spot, made, for example, by light that includes only the fundamental mode.
  • a different specific pattern can be required, such as one that is achieved by generating light having various selected modes.
  • a conventional method used to control the lateral modes of the light includes forming a positive conductor on top of the semiconductor layer, having a lateral dimension selected to only support the desired modes.
  • An insulator can be placed between the active layer and the positive conductor layer outside of that lateral dimension, to prevent current flowing from the positive conductor outside of the selected region.
  • This method works for low power applications, but when the gain current flowing from the positive to the negative conductor and across the active layer exceeds a certain value, the current tends to spread in the lateral direction as it travels perpendicular to the layers.
  • the degree of lateral current spreading can also increase with increased gain or drive current levels. This forms areas of high gain in the active layer that are larger than what is necessary to support the selected modes. When this occurs, extraneous modes can be supported by these enlarged gain areas of the active layer, and the light emitted is no longer of only the desired mode.
  • the present invention is directed to a semiconductor laser diode and a related method that is adapted to control the lateral modes of the laser light generated, so that only desired modes are supported.
  • this result is achieved by controlling the lateral spre'ad of the electric current that passes through the active layer, so that only a selected portion of the active layer has a high gain, resulting in amplification of only the light crossing that portion of the layer.
  • the other portions of the active layer that flank the selected active region inhibit the flow of current, and therefore have a lower gain which results in less amplification, or no amplification of the light passing through those portions.
  • the lateral dimensions of the high gain portion of the active layer can be selected to support only desired modes of the laser light, such as the fundamental mode or a combination of the fundamental and other modes.
  • the lateral control of the electric current is achieved by implanting high energy ions, such as protons, in the portions of the active layer that require a reduced conductivity, while shielding from the ion implant the portion of the active layer where high conductivity, therefore high gain is desired.
  • This shielding can be obtained, for example, by placing a photoresist layer between the source of ions and the active layer.
  • the photoresist layer can be shaped with openings that correspond to the size of the desired conductive portion of the active layer.
  • the invention is a ridge waveguide semiconductor laser diode adapted to support desired lateral modes of generated light, comprising a first conductor layer for application of a current, a second conductor layer facing the first conductor layer, an active layer disposed between the first and second conductor layers, a conduction region of the active layer adapted for conducting the current, and reduced conductivity regions of the active layer, flanking the conduction region, adapted to impede passage of the current.
  • Figure 1 is a schematic perspective view of one embodiment of a semiconductor laser diode incorporating the present invention
  • Figure 2 is a schematic perspective view of the semiconductor laser diode shown in Figure 1, also including a barrier layer;
  • Figure 3 is a schematic front elevation view showing a detail of the embodiment of Figure 1;
  • Figure 4 is a schematic view showing individual semiconductor laser elements disposed in an array.
  • Semiconductor laser diodes are used in a variety of devices such as optical data storage and compact disc drives, for printing processes such as those used in laser printers, and also for displays.
  • a plurality of laser diodes can be assembled in an array, so that the light from all of the arrayed laser diodes has the same mode and in some cases also the same phase.
  • a gain current up to 20 or 30 times the threshold current of the active layer in the laser diodes can be used to obtain a high brightness spot or beam from the semiconductor material.
  • Figure 1 shows one embodiment of a semiconductor laser diode according to the present invention.
  • Semiconductor lasers consist of epitaxial layers grown on a single-crystal substrate 15. Typically, the substrate 15 is n- type.
  • the exemplary semiconductor laser diode 1 has an active layer 10 that can include a quantum well structure. Active layer 10 can be formed, for example, of un-doped InGaAs or InGaAsP.
  • a positive conductor 12 can be applied facing one surface of the active layer 10, and several p-type clad region layers and confinement layers can also be deposited in region 18, between the active layer 10 and the positive conductor 12, according to a conventional manner of construction of semiconductor laser devices.
  • a negative conductor layer 14 can be formed on the substrate 15, facing the opposite surface of active layer 10.
  • a conventional arrangement of confinement layers and n-type clad layers can also be disposed in region 20, between the active layer 10 and the substrate 15.
  • Positive conductor layer 12 can be a strip as shown in Figure 1, or can extend the entire width of semiconductor laser diode 1.
  • the strip shaped positive conductor layer 12 can preferably have dimensions corresponding to a region of active layer 10 that supports the desired optical modes.
  • a dielectric insulator layer 16 can be used to prevent the flow of current from entering the top layers of region 18, outside of a selected lateral area. Insulator layer 16 thus defines an opening 17 in the insulator layer, that corresponds to the area where positive conductor 12 is in contact with region 18.
  • semiconductor laser diode 1 can also include a ridged waveguide 22 extending parallel to a longitudinal axis of semiconductor laser device 1, and extending along the entire length L of the device.
  • ridge waveguide 22 can have a width of about 3 - 5 microns. Ridge waveguide 22 channels the light being emitted and amplified in active layer 10, so that the light is directed for the most part along the longitudinal dimension of the semiconductor laser device 1.
  • the extent of the laser light is governed by the width of the waveguide, the lateral index step between the waveguide and the region external to it, and the amount of lateral current spread.
  • the lateral index step is the index difference between the region under the ridge 22, and the regions under the channels 23 on each side of the ridge 22.
  • the waveguide is "gain guided". In this case, the light is guided along the current path by virtue of the absorption difference, or gain vs. loss ratio, between the current flow region and its lateral regions.
  • the waveguide is "index guided", so that guiding of the light is achieved by the index step.
  • Index guiding can be more advantageous than gain guiding, because it results in single-spatial mode operation and reduced astigmatism.
  • active layer 10 is divided in a defined gain region 24 of high conductivity, through which the current flowing from positive conductor element 12 to negative conductor element 14 can easily pass, and flanking regions 26 of reduced conductivity, through which the current cannot easily pass.
  • the current flowing from positive conductor element 12 to negative element 14 is prevented from spreading laterally away from defined gain region 24, and follows a path shown by the solid line 32.
  • the lateral dimension of the high gain portion of active layer 10 is thus limited to the size of defined gain region 24.
  • defined gain region 24 could be sized to only support the fundamental mode of the laser light in active layer 10, so that a sharp, single spot output laser beam can be generated by the device. Generation of laser light of the fundamental mode is useful for lasers used in telecommunications.
  • a non- gaussian beam formed by the fundamental and the second transverse mode can be useful in laser printing applications to improve printing sharpness.
  • the reduced conductivity regions 26 formed in the active layer 10 can be obtained, for example, by implanting ions such as protons in the material of active layer 10.
  • the proton implant damages the structure of the active layer 10, and causes the affected region of active layer 10 to become nonconducting.
  • the extent of the transformation incurred by active layer 10 is dependent on the strength and the duration of the proton implant.
  • successful results can be obtained by implanting protons having an energy of between approximately 130 KeV and 170 KeV.
  • the implant can preferably have a duration of between about 1 and 5 minutes, and can be repeated more than once.
  • the laser light is amplified within a light amplification portion 30 of defined gain region 24.
  • the actual shape of light amplification portion 30 depends on the desired mode being sustained. For example, in the case shown, the fundamental mode is supported, which results in a light amplification portion 30 shaped like a single elliptical spot through active layer 10, where the light amplification takes place.
  • reduced conductivity regions 26 The location within active layer 10 of reduced conductivity regions 26 must be selected carefully. The width of the defined gain region 24 of active layer 10 determines which lateral modes of the laser light will be supported, therefore reduced conductivity regions 26 must be placed sufficiently close to light amplification portion 30 of active layer 10, so that additional modes will not be sustained by the active layer 10.
  • interface 40 must not be so far from light amplification portion 30 that the defined gain region 24 can support modes other than the desired mode of the laser light.
  • semiconductor laser diode 1 The manufacturing process for semiconductor laser diode 1 will be described with reference to Figure 2.
  • Positive and negative conductor layers 12 and 14, insulating layer 16, active layer 10 and the remaining layers forming semiconductor laser diode 1 are grown in a conventional manner.
  • reduced conductivity areas 26 are formed by implanting protons in the layers of the device.
  • a source of protons 44 can be, for example, hydrogen.
  • a barrier layer such as photoresist layer 42 is used to shield from the protons areas of active layer 10 that are to remain conductive.
  • photoresist layer 42 can be placed above defined gain region 24, so that protons generated by source 44 are stopped by photoresist layer 42, and do not affect defined gain region 24.
  • the remaining portions of the device, above and including the reduced conductivity regions 26, are implanted with protons, resulting in a loss of conductivity for those regions.
  • only sections lying below the channels 23 on the sides of the ridge 22 are implanted.
  • the depth of the implant can correspond approximately to the thickness of clad region 18 and can reach through active layer 10.
  • FIG 3 shows a detail of a region of the semiconductor laser depicted in Figure 1.
  • This exemplary embodiment includes an implant region of constant depth 'd' obtained, for example, with an implant of given energy and duration. Because of the presence of channels 23 on the sides of ridge 22, the implant depth 'd' reaches active layer 10 in regions 26, below channels 23. Regions 26', located beyond channels 23, also receive an implant of depth 'd'. However, the layers of the laser diode above the active layer 10 have greater thickness at that point, and thus the implant in region 26' may not reach the active layer 10.
  • Figure 3 also shows lines 32 that indicate the path of current traveling through active layer 10 from positive conductor 12, and lines 33 indicating the path of spreading current blocked by reduced conductivity areas 26.
  • Protons from source 44 can travel across metallic layers and the various layers that form semiconductor laser diode 1, so that the proton implant can take place in a single step process, after all the layers of the wafer have been grown in a conventional manner.
  • Photoresist layer 42 can be made, for example, of a long chain polymer such as SHIPLEY Photoresist Type AZ
  • absorb protons from source 44 can be used in photoresist layer 42.
  • the loss in selected regions of the active layer 10 can be controlled with the location and energy of the implant. In this manner, the waveguide loss in the lateral direction can be selected by modifying the location of the implant.
  • This loss introduced by the implant is another mechanism that can be used to control the laser light mode in the waveguide, in addition to controlling the current spread in reduced conductivity areas 26.
  • photoresist layer 42 can be placed above the outer surface of conductor layer 12, and can be removed after the implant has been performed.
  • other configurations of photoresist layer 42 can be utilized, as long as photoresist layer 42 is placed between the source of protons 44 and the areas that are to remain conductive after the implant.
  • FIG. 4 shows an exemplary array of individually-addressable laser elements 50.
  • Each element 50 includes a ridge single-mode waveguide element 52, shown upside down in the figure.
  • a dielectric layer 54 and a p-side metallization layer 56 are formed with an appropriate shape and thickness to define the ridges 58.
  • the elements 50 are thermally and electrically separated by V- grooves 64, etched through the active region 60.
  • V- grooves 64 etched through the active region 60.
  • the element 50 are separated by approximately 50 ⁇ m, resulting in an array that
  • All the laser elements in the exemplary embodiment produce a spot of laser light 62 in active layer 60 having the same mode characteristics.

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  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)

Abstract

L'invention concerne une diode (1) laser à semi-conducteurs et un procédé consistant à commander la trajectoire du courant dans le dispositif entre les conducteurs positifs (12) et négatifs (14). La répartition latérale du courant de gain dans les régions actives est évitée par l'implantation de protons dans certaines zones de la couche active (10) bordant une zone (24) de gain souhaitée. Les zones (26) implantées deviennent moins conductrices et évitent la répartition latérale du courant de gain. La position des zones (26) implantées peut être choisie de manière que le courant de gain ne croise qu'une partie de la couche active (10) supportant des modes latéraux souhaités de la lumière laser.
PCT/US2000/031048 1999-11-12 2000-11-10 Commande de la repartition du courant dans des diodes lasers a semi-conducteurs WO2001035506A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP00980351A EP1247316A4 (fr) 1999-11-12 2000-11-10 Commande de la repartition du courant dans des diodes lasers a semi-conducteurs
JP2001537143A JP2003515250A (ja) 1999-11-12 2000-11-10 半導体レーザダイオードの電流拡散制御
AU17626/01A AU1762601A (en) 1999-11-12 2000-11-10 Control of current spreading in semiconductor laser diodes
CA002388858A CA2388858A1 (fr) 1999-11-12 2000-11-10 Commande de la repartition du courant dans des diodes lasers a semi-conducteurs

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US16486499P 1999-11-12 1999-11-12
US60/164,864 1999-11-12

Publications (2)

Publication Number Publication Date
WO2001035506A1 true WO2001035506A1 (fr) 2001-05-17
WO2001035506A9 WO2001035506A9 (fr) 2002-05-23

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PCT/US2000/031048 WO2001035506A1 (fr) 1999-11-12 2000-11-10 Commande de la repartition du courant dans des diodes lasers a semi-conducteurs

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EP (1) EP1247316A4 (fr)
JP (1) JP2003515250A (fr)
AU (1) AU1762601A (fr)
CA (1) CA2388858A1 (fr)
WO (1) WO2001035506A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100421320C (zh) * 2003-03-08 2008-09-24 三星电子株式会社 半导体激光二极管及包含其的半导体激光二极管组件
US8597962B2 (en) 2010-03-31 2013-12-03 Varian Semiconductor Equipment Associates, Inc. Vertical structure LED current spreading by implanted regions
CN111082314A (zh) * 2019-12-11 2020-04-28 中国科学院长春光学精密机械与物理研究所 一种半导体激光器及其制备方法

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US5696784A (en) * 1996-04-19 1997-12-09 Opto Power Corporation Reduced mode laser and method of fabrication

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US5219785A (en) * 1989-01-27 1993-06-15 Spectra Diode Laboratories, Inc. Method of forming current barriers in semiconductor lasers
US5138626A (en) * 1990-09-12 1992-08-11 Hughes Aircraft Company Ridge-waveguide buried-heterostructure laser and method of fabrication
JPH07118570B2 (ja) * 1993-02-01 1995-12-18 日本電気株式会社 面発光素子およびその製造方法
JPH06326419A (ja) * 1993-04-20 1994-11-25 Xerox Corp モノリシック半導体発光アレイ
US5804461A (en) * 1994-12-22 1998-09-08 Polaroid Corporation Laser diode with an ion-implant region
US6044098A (en) * 1997-08-29 2000-03-28 Xerox Corporation Deep native oxide confined ridge waveguide semiconductor lasers

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
US5696784A (en) * 1996-04-19 1997-12-09 Opto Power Corporation Reduced mode laser and method of fabrication

Non-Patent Citations (1)

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See also references of EP1247316A4 *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100421320C (zh) * 2003-03-08 2008-09-24 三星电子株式会社 半导体激光二极管及包含其的半导体激光二极管组件
US8597962B2 (en) 2010-03-31 2013-12-03 Varian Semiconductor Equipment Associates, Inc. Vertical structure LED current spreading by implanted regions
CN111082314A (zh) * 2019-12-11 2020-04-28 中国科学院长春光学精密机械与物理研究所 一种半导体激光器及其制备方法
CN111082314B (zh) * 2019-12-11 2021-10-08 中国科学院长春光学精密机械与物理研究所 一种半导体激光器及其制备方法

Also Published As

Publication number Publication date
AU1762601A (en) 2001-06-06
EP1247316A2 (fr) 2002-10-09
EP1247316A4 (fr) 2006-01-04
WO2001035506A9 (fr) 2002-05-23
JP2003515250A (ja) 2003-04-22
CA2388858A1 (fr) 2001-05-17

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