WO2015135524A1 - Monolithic miniature broadband light source for measurements by means of fbg strain sensors - Google Patents

Monolithic miniature broadband light source for measurements by means of fbg strain sensors Download PDF

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Publication number
WO2015135524A1
WO2015135524A1 PCT/DE2015/000117 DE2015000117W WO2015135524A1 WO 2015135524 A1 WO2015135524 A1 WO 2015135524A1 DE 2015000117 W DE2015000117 W DE 2015000117W WO 2015135524 A1 WO2015135524 A1 WO 2015135524A1
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semiconductor
light source
pair
contacts
inp semiconductor
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PCT/DE2015/000117
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German (de)
French (fr)
Inventor
Pieter Lucas KAT
Ronald Gijsbertus BROEKE
Vincent Johannes DOCTER
Jochen Maul
Karl-Heinz Haase
Bernd Günther
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Hottinger Baldwin Messtechnik Gmbh
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Publication of WO2015135524A1 publication Critical patent/WO2015135524A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/08—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
    • G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
    • G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/26—Materials of the light emitting region
    • H01L33/30—Materials of the light emitting region containing only elements of group III and group V of the periodic system
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/36—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
    • H01L33/38—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape
    • H01L33/385—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes with a particular shape the electrode extending at least partially onto a side surface of the semiconductor body

Definitions

  • the invention relates to a monolithic miniature broadband light source with improved light output for measurements with FBG strain sensors.
  • the light intensity within the optical fiber and in particular at the location of the Bragg grating is of particular importance.
  • the intensity of the light reflected back from the Bragg grating to the measuring device determines the signal-to-noise ratio and thus the achievable metrological resolution. Therefore, a predetermined minimum light output of such a light source is required.
  • interrogators i. Devices for the evaluation of FBG measuring signals.
  • Such interrogators should e.g. attached to the wings of wind power plants. Relatively large and heavy conventional light sources are not suitable for such applications.
  • Miniature light sources such as InGaAsP structures, are well known in the art. Due to their small size, ie the dimensions of only a few micrometers in width and height, these have only a low light output. If sections of this structure are excited by the application of a voltage to emit light, their light output is not always sufficient to operate a longer measuring chain equipped with FBG sensors. In the past, the solution to this problem has been the use of larger and thus more powerful light sources, but this is contrary to the requirement for small and lightweight interrogators described above. In addition to the lower light output resulting from the low volume, the following problem still exists with these InGaAsP semiconductor light sources:
  • such structures Due to the manufacturing process, such structures have at least two opposing surfaces. Between these surfaces, the induced light is reflected. If the applied electrical voltage has reached a certain value, thereby the so-called laser threshold is achieved. Then a constant laser light arises, which on the one hand has a high intensity, but on the other hand, due to its very small bandwidth is not suitable for measurements with FBG sensors.
  • the laser threshold is exceeded, so that the light source continues to work as a broadband light source even at a higher voltage and does not go into the laser mode.
  • the inventors looked for ways to raise the laser threshold. The inventors found that decreasing the reflectivity of the reflective layers results in increasing the lasing threshold. To reduce the reflectivity of reflective layers, two possibilities are known:
  • Coating the respective surface by means of a light absorbing layer e.g. according to the method described in document EP 2669718 A1, or coating the respective surface with a so-called antireflection layer according to a method used for the antireflection of spectacle lenses or solar cells.
  • the light source is made by a metal organic vapor phase epitaxy process or a sputtering process
  • the application of such absorbent or anti-reflective layers is either not possible or involves significant technological difficulties. This is primarily because the structures are produced in layers and horizontally relative to the carrier substrate, but the surfaces to be coated are arranged vertically. Coating these surfaces would provide an additional, make extremely complex technology step necessary. Since the layer produced is an absorption layer and it heats up, sufficient heat dissipation would also have to be provided.
  • the object of the invention is to provide a miniature broadband light source for use in strain measurement by means of FBG sensors, which generates light with a broadband spectrum, but with a much higher intensity compared to previous miniature light sources.
  • This object is achieved by means of a monolithic, broadband, broadband light source according to claim 1, wherein an InGaAsP semiconductor produced by means of a Metal Organic Vapor Phase Epitaxy process or a sputtering process is sandwiched between a p-type InP semiconductor and an n -nnP semiconductor is embedded.
  • the InGaAsP semiconductor including the p-InP semiconductor and the n-InP semiconductor has a longitudinal extent L. The light exits from a light exit surface.
  • the p-type InP semiconductor and the n-type InP semiconductor are provided with paired metallic contacts.
  • a first pair of contacts extends for at least 60% of the length L of the p-type semiconductor and the n-type semiconductor.
  • a second contact pair is galvanically separated from the first contact pair by a gap. The contact surfaces of the second pair of contacts are galvanically connected to each other.
  • the first contact pair extends over at least 80% of the length L of the p-type InP semiconductor and the n-type InP semiconductor, resulting in a light source of even smaller size.
  • Fig. 1 shows a monolithic miniature broadband light source in perspective view.
  • Fig. 2a shows the light intensities of a broadband light source according to the prior art.
  • Fig. 2b shows the light intensities of a broadband light source with higher
  • an InGaAsP semiconductor 1 is disposed between a p-type InP 2 and an n-InP type semiconductor 3, these three semiconductor structures being made by a Metal Organic Vapor Phase Epitaxy process or a sputtering process.
  • the InGaAsP semiconductor having the p-type InP semiconductor and the n-type InP semiconductor has a length L of 700 microns. Induced light emerges from a light exit surface 1a of the InGaAsP semiconductor 1.
  • the p-InP semiconductor 2 and the n-InP semiconductor 3 are provided with metallic contacts forming contact pairs.
  • a first contact pair 4a, 4b extends over at least 60% of the length L of these semiconductor structures.
  • a second contact pair 5a, 5b extends over the remainder of the length L of the semiconductor structures.
  • the pairs of contacts 4a, 4b and 5a, 5b are galvanically separated from each other by a gap 6.
  • the contact surfaces of the second contact pair 5a, 5b are electrically connected to one another via an electrical conductor 7.
  • Fig. 2a serves to explain first the function of a light source according to the prior art.
  • a conventional light source according to the prior art is essentially a light source having the structure shown in FIG. 1, but includes only the portion extending from the light exit surface 1a to the gap 6 in this figure.
  • the abscissa represents the light wavelength ⁇ and the ordinate the photon flux density J.
  • the curve a shows a broadband light spectrum at a first voltage U1.
  • the curve b shows a broadband light spectrum at a second voltage U2, which is higher than the first voltage U1.
  • the photon flux density J is also higher, which is equivalent to a higher light intensity.
  • Reference numeral 8 denotes the laser threshold.
  • Fig. 2b illustrates the effect of the light source shown in Fig. 1 with the higher light intensity, wherein as already described a second pair of contacts 5a and 5b is provided, which by a gap 6 from the first pair of contacts 4a and 4b spaced and thus galvanically separated from this is.
  • the effect caused by the electrical conductor 7 galvanic short circuit of the contact pair 5a, 5b causes the light exit surface 1a opposite surface is no longer available as an internal reflection surface available.
  • the induced light beams can no longer be reflected between the surfaces, so that the formation of a laser effect is prevented.
  • the laser threshold is raised to a higher level denoted by reference numeral 8new so that the goal is achieved of generating light with a broadband spectrum and high intensity.

Abstract

The invention relates to a semiconductor-based monolithic miniature broadband light source having improved light output for measurement by means of FBG strain sensors, wherein an InGaAsP semiconductor (1) is embedded between a p-lnP semiconductor (2) and an n-lnP semiconductor (3), wherein the InGaAsP semiconductor (1) has a length (L), and the p-lnP semiconductor (2) and the n-lnP semiconductor (3) are provided with metal contacts disposed in pairs. A first pair of contacts (4a, 4b) extends over at least 60% of the length (L) of the p-lnP semiconductor (2) and of the n-lnP semiconductor (3), and the first pair of contacts (4a, 4b) and the second pair of contacts (5a, 5b) are separated from one another galvanically by a gap (6) and the two contact surfaces of the second pair of contacts (5a, 5b) are connected to one another galvanically by an electrical conductor (7).

Description

Monolithische Miniatur-Breitband-Lichtquelle für Messungen  Monolithic miniature broadband light source for measurements
mit FBG-Dehnungssensoren  with FBG strain sensors
Die Erfindung betrifft eine monolithische Miniatur-Breitband-Lichtquelle mit verbesserter Lichtleistung für Messungen mit FBG-Dehnungssensoren. The invention relates to a monolithic miniature broadband light source with improved light output for measurements with FBG strain sensors.
In der optischen Dehnungsmesstechnik mit Faser-Bragg-Gittern (FBG) ist die Lichtintensität innerhalb der Lichtfaser und insbesondere am Ort des Bragg-Gitters von besonderer Bedeutung. Die Intensität des vom Bragg-Gitter zum Messgerät zurückreflektierten Lichts entscheidet über das Signal-Rausch-Verhältnis und somit über die erzielbare messtechnische Auflösung. Daher ist eine vorbestimmte Mindestlichtleistung einer solchen Lichtquelle erforderlich. In optical strain measurement with fiber Bragg gratings (FBG), the light intensity within the optical fiber and in particular at the location of the Bragg grating is of particular importance. The intensity of the light reflected back from the Bragg grating to the measuring device determines the signal-to-noise ratio and thus the achievable metrological resolution. Therefore, a predetermined minimum light output of such a light source is required.
Für diese Messtechnik besteht ein Bedarf an Lichtquellen mit geringer Masse, die für sogenannte Interrogatoren, d.h. Vorrichtungen zur Auswertung von FBG- Messsignalen, benötigt werden. Solche Interrogatoren sollen z.B. an Flügeln von Windkraftwerken befestigt werden. Relativ große und schwere herkömmliche Lichtquellen sind für derartige Anwendungsfälle nicht geeignet. For this measurement technique, there is a need for low mass light sources suitable for so-called interrogators, i. Devices for the evaluation of FBG measuring signals, are needed. Such interrogators should e.g. attached to the wings of wind power plants. Relatively large and heavy conventional light sources are not suitable for such applications.
Aus dem Stand der Technik sind Miniaturlichtquellen, wie z.B. InGaAsP-Struk- turen, hinreichend bekannt. Diese weisen wegen ihrer geringen Größe, d.h. den nur wenige Mikrometer betragenden Abmessungen in der Breite und der Höhe, nur eine geringe Lichtleistung auf. Werden Abschnitte dieser Struktur durch Anlegen einer Spannung zur Lichtemission angeregt, reicht deren Lichtleistung nicht immer aus, um damit eine mit FBG-Sensoren bestückte längere Messkette zu betreiben. In der Vergangenheit bestand die Lösung dieses Problems in der Nutzung größerer und somit leistungsfähigerer Lichtquellen, was aber dem vorstehend beschriebenen Erfordernis nach kleinen und leichten Interrogatoren entgegensteht. Neben der aus dem geringen Volumen resultierenden geringeren Lichtleistung gibt es bei diesen InGaAsP-Halbleiterlichtquellen noch folgendes Problem: Miniature light sources, such as InGaAsP structures, are well known in the art. Due to their small size, ie the dimensions of only a few micrometers in width and height, these have only a low light output. If sections of this structure are excited by the application of a voltage to emit light, their light output is not always sufficient to operate a longer measuring chain equipped with FBG sensors. In the past, the solution to this problem has been the use of larger and thus more powerful light sources, but this is contrary to the requirement for small and lightweight interrogators described above. In addition to the lower light output resulting from the low volume, the following problem still exists with these InGaAsP semiconductor light sources:
Durch den Herstellungsprozess bedingt, weisen derartige Strukturen mindestens zwei einander gegenüberliegende Flächen auf. Zwischen diesen Flächen wird das induzierte Licht reflektiert. Wenn die angelegte elektrische Spannung einen bestimmten Wert erreicht hat, wird dadurch auch die sogenannte Laserschwelle erreicht. Dann entsteht ein konstantes Laserlicht, welches einerseits eine hohe Intensität hat, aber andererseits auf Grund seiner sehr kleinen Bandbreite für Messungen mit FBG-Sensoren nicht geeignet ist. Due to the manufacturing process, such structures have at least two opposing surfaces. Between these surfaces, the induced light is reflected. If the applied electrical voltage has reached a certain value, thereby the so-called laser threshold is achieved. Then a constant laser light arises, which on the one hand has a high intensity, but on the other hand, due to its very small bandwidth is not suitable for measurements with FBG sensors.
Bei der vorliegenden Aufgabenstellung kommt es darauf an, die Lichtintensität der Lichtquelle zu erhöhen, was durch die Erhöhung der angelegten Spannung erreichbar wäre. Es muss jedoch verhindert werden, dass die Laserschwelle überschritten wird, damit die Lichtquelle auch bei einer höheren Spannung weiterhin als Breitbandlichtquelle arbeitet und nicht in den Lasermodus übergeht. Die Erfinder suchten nach Möglichkeiten, um die Laserschwelle anzuheben. Die Erfinder fanden heraus, dass eine Verminderung der Reflexionsfähigkeit der reflektierenden Schichten zur Erhöhung der Laserschwelle führt. Um die Reflexionsfähigkeit von reflektierenden Schichten zu senken, sind zwei Möglichkeiten bekannt: In the present task, it is important to increase the light intensity of the light source, which could be achieved by increasing the applied voltage. However, it must be prevented that the laser threshold is exceeded, so that the light source continues to work as a broadband light source even at a higher voltage and does not go into the laser mode. The inventors looked for ways to raise the laser threshold. The inventors found that decreasing the reflectivity of the reflective layers results in increasing the lasing threshold. To reduce the reflectivity of reflective layers, two possibilities are known:
Beschichten der jeweiligen Fläche mittels einer Licht absorbierenden Schicht, wie z.B. nach dem im Dokument EP 2669718 A1 beschriebenen Verfahren, oder Beschichten der jeweiligen Fläche mit einer sogenannten Antireflexschicht nach einem für das Entspiegeln von Brillengläsern oder Solarzellen angewendeten Verfahren. Coating the respective surface by means of a light absorbing layer, e.g. according to the method described in document EP 2669718 A1, or coating the respective surface with a so-called antireflection layer according to a method used for the antireflection of spectacle lenses or solar cells.
Wenn jedoch die Lichtquelle mittels eines Metal-Organic-Vapour-Phase-Epitaxy- Prozesses oder eines Sputter-Prozesses hergestellt wird, ist das Aufbringen solcher Schichten mit absorbierender oder entspiegelnder Wirkung entweder nicht möglich oder mit erheblichen technologischen Schwierigkeiten verbunden. Das liegt vorrangig daran, dass die Herstellung der Strukturen schichtweise und waagerecht zum Trägersubstrat erfolgt, die zu beschichtenden Flächen jedoch senkrecht angeordnet sind. Das Beschichten dieser Flächen würde einen zusätzlichen, äußerst aufwendigen Technologieschritt erforderlich machen. Da die erzeugte Schicht eine Absorptionsschicht ist und diese sich erwärmt, müsste auch für eine ausreichende Wärmeableitung gesorgt werden. However, when the light source is made by a metal organic vapor phase epitaxy process or a sputtering process, the application of such absorbent or anti-reflective layers is either not possible or involves significant technological difficulties. This is primarily because the structures are produced in layers and horizontally relative to the carrier substrate, but the surfaces to be coated are arranged vertically. Coating these surfaces would provide an additional, make extremely complex technology step necessary. Since the layer produced is an absorption layer and it heats up, sufficient heat dissipation would also have to be provided.
Somit besteht die Aufgabe der Erfindung darin, eine Miniatur-Breitband-Lichtquelle für den Einsatz zur Dehnungsmessung mittels FBG-Sensoren bereitzustellen, die im Vergleich zu bisherigen Miniaturlichtquellen ein Licht mit einem Breitbandspektrum, aber mit wesentlich höherer Intensität erzeugt. Thus, the object of the invention is to provide a miniature broadband light source for use in strain measurement by means of FBG sensors, which generates light with a broadband spectrum, but with a much higher intensity compared to previous miniature light sources.
Diese Aufgabe wird mittels einer monolitischen Miniatur-Breitband-Lichtquelle nach Anspruch 1 gelöst, wobei ein mittels eines Metal-Organic-Vapour-Phase- Epitaxy-Prozesses oder eines Sputter-Prozesses erzeugter InGaAsP-Halbleiter zwischen einem p-lnP-Halbleiter und einem n-lnP-Halbleiter eingebettet ist. Der InGaAsP-Halbleiter einschließlich des p-lnP-Halbleiters und des n-lnP-Halbleiters weist eine Längserstreckung L auf. Das Licht tritt aus einer Lichtaustrittsfläche aus. This object is achieved by means of a monolithic, broadband, broadband light source according to claim 1, wherein an InGaAsP semiconductor produced by means of a Metal Organic Vapor Phase Epitaxy process or a sputtering process is sandwiched between a p-type InP semiconductor and an n -nnP semiconductor is embedded. The InGaAsP semiconductor including the p-InP semiconductor and the n-InP semiconductor has a longitudinal extent L. The light exits from a light exit surface.
Der p-lnP-Halbleiter und der n-lnP-Halbleiter sind mit paarig angeordneten metallischen Kontakten versehen. Ein erstes Kontaktpaar erstreckt sich über wenigstens 60 % der Länge L des p-lnP-Halbleiters und des n-lnP-Halbleiters. Ein zweites Kontaktpaar ist durch einen Spalt galvanisch vom ersten Kontaktpaar getrennt. Die Kontaktflächen des zweiten Kontaktpaars sind galvanisch miteinander verbunden. The p-type InP semiconductor and the n-type InP semiconductor are provided with paired metallic contacts. A first pair of contacts extends for at least 60% of the length L of the p-type semiconductor and the n-type semiconductor. A second contact pair is galvanically separated from the first contact pair by a gap. The contact surfaces of the second pair of contacts are galvanically connected to each other.
Nach Anspruch 2 erstreckt sich das erste Kontaktpaar über wenigstens 80 % der Länge L des p-lnP-Halbleiters und des n-lnP-Halbleiters, was zu einer Lichtquelle mit noch kleinerer Baugröße führt. According to claim 2, the first contact pair extends over at least 80% of the length L of the p-type InP semiconductor and the n-type InP semiconductor, resulting in a light source of even smaller size.
Nach Anspruch 3 liegen ein erster Kontakt (4a) des ersten Kontaktpaars (4a, 4b) und ein erster Kontakt (5a) des zweiten Kontaktpaars (5a, 5b) auf gleichem elektrischem Potenzial, was unter vorbestimmten Bedingungen zu einer technologischen Vereinfachung führt, da die Kontakte dann als gemeinsame Platte ausgebildet sein können. Die Erfindung wird anhand von schematischen Zeichnungen näher erläutert: According to claim 3, a first contact (4a) of the first pair of contacts (4a, 4b) and a first contact (5a) of the second pair of contacts (5a, 5b) at the same electrical potential, which leads to a technological simplification under predetermined conditions, since the Contacts can then be designed as a common plate. The invention will be explained in more detail with reference to schematic drawings:
Fig. 1 zeigt eine monolithische Miniatur-Breitband-Lichtquelle in perspektivischer Darstellung. Fig. 1 shows a monolithic miniature broadband light source in perspective view.
Fig. 2a zeigt die Lichtintensitäten einer Breitbandlichtquelle nach dem Stand der Technik. Fig. 2a shows the light intensities of a broadband light source according to the prior art.
Fig. 2b zeigt die Lichtintensitäten einer Breitbandlichtquelle mit höherer Fig. 2b shows the light intensities of a broadband light source with higher
Lichtleistung.  Light output.
Wie Figur 1 zeigt, ist zwischen einem p-lnP-Halbleiter 2 und einem n-lnP- Halbleiter 3 ein InGaAsP-Halbleiter 1 angeordnet, wobei diese drei Halbleiterstrukturen mittels einem Metal Organic Vapour Phase Epitaxy-Prozess oder einem Sputter-Prozess hergestellt sind. Der InGaAsP-Halbleiter mit dem p-lnP-Halbleiter und dem n-lnP-Halbleiter weist eine Länge L von 700 Mikrometern auf. Induziertes Licht tritt aus einer Lichtaustrittsfläche 1a des InGaAsP-Halbleiters 1 aus. As shown in FIG. 1, an InGaAsP semiconductor 1 is disposed between a p-type InP 2 and an n-InP type semiconductor 3, these three semiconductor structures being made by a Metal Organic Vapor Phase Epitaxy process or a sputtering process. The InGaAsP semiconductor having the p-type InP semiconductor and the n-type InP semiconductor has a length L of 700 microns. Induced light emerges from a light exit surface 1a of the InGaAsP semiconductor 1.
Der p-lnP-Halbleiter 2 und der n-lnP-Halbleiter 3 sind mit metallischen Kontakten versehen, die Kontaktpaare bilden. Ein erstes Kontaktpaar 4a, 4b erstreckt sich über wenigstens 60% der Länge L dieser Halbleiterstrukturen. Ein zweites Kontaktpaar 5a, 5b erstreckt sich über den Rest der Länge L der Halbleiterstrukturen. Die Kontaktpaare 4a, 4b und 5a, 5b sind durch einen Spalt 6 galvanisch voneinander getrennt. Die Kontaktflächen des zweiten Kontaktpaars 5a, 5b sind über einen elektrischen Leiter 7 galvanisch miteinander verbunden. The p-InP semiconductor 2 and the n-InP semiconductor 3 are provided with metallic contacts forming contact pairs. A first contact pair 4a, 4b extends over at least 60% of the length L of these semiconductor structures. A second contact pair 5a, 5b extends over the remainder of the length L of the semiconductor structures. The pairs of contacts 4a, 4b and 5a, 5b are galvanically separated from each other by a gap 6. The contact surfaces of the second contact pair 5a, 5b are electrically connected to one another via an electrical conductor 7.
Die Fig. 2a dient dazu, zuerst die Funktion einer Lichtquelle nach dem Stand der Technik zu erläutern. Eine solche herkömmliche Lichtquelle gemäß dem Stand der Technik ist im Wesentlichen eine Lichtquelle mit dem in Figur 1 gezeigten Aufbau, umfasst aber nur den sich von der Lichtaustrittsfläche 1a bis zum Spalt 6 erstreckenden Abschnitt in dieser Figur. Fig. 2a serves to explain first the function of a light source according to the prior art. Such a conventional light source according to the prior art is essentially a light source having the structure shown in FIG. 1, but includes only the portion extending from the light exit surface 1a to the gap 6 in this figure.
Bei dem in Figur 2a dargestellten Diagramm ist auf der Abszisse die Lichtwellenlänge λ und auf der Ordinate die Photonenflussdichte J aufgetragen. Die Kurve a zeigt ein Breitbandlichtspektrum bei einer ersten Spannung U1. Die Kurve b zeigt ein Breitbandlichtspektrum bei einer zweiten Spannung U2, die höher ist als die erste Spannung U1. Demzufolge ist auch die Photonenflussdichte J höher, was gleichbedeutend mit einer höheren Lichtintensität ist. Mit Bezugszeichen 8 ist die Laserschwelle bezeichnet. Beim Anlegen einer noch höheren Spannung, bei welcher die Photonenflussdichte J die Laserschwelle 8 überschreitet, wird die Breitbandlichtquelle zu einer Laserlichtquelle mit einem schmalbandigem Lichtspektrum c, welches für die Messung mit FBG-Sensoren nicht geeignet ist. In the diagram shown in FIG. 2a, the abscissa represents the light wavelength λ and the ordinate the photon flux density J. The curve a shows a broadband light spectrum at a first voltage U1. The curve b shows a broadband light spectrum at a second voltage U2, which is higher than the first voltage U1. As a result, the photon flux density J is also higher, which is equivalent to a higher light intensity. Reference numeral 8 denotes the laser threshold. When an even higher voltage is applied, at which the photon flux density J exceeds the laser threshold 8, the broadband light source becomes a laser light source with a narrow-band light spectrum c, which is not suitable for measurement with FBG sensors.
Die Fig. 2b veranschaulicht die Wirkung der in Fig. 1 gezeigten Lichtquelle mit der höheren Lichtintensität, wobei wie bereits beschrieben ein zweites Kontaktpaar 5a und 5b vorgesehen ist, welches durch einen Spalt 6 vom ersten Kontaktpaar 4a und 4b beabstandet und somit galvanisch von diesem getrennt ist. Durch den vom elektrischen Leiter 7 bewirkten galvanischen Kurzschluss des Kontaktpaares 5a, 5b wird bewirkt, dass die der Lichtaustrittsfläche 1a gegenüberliegende Fläche nicht mehr als interne Reflexionsfläche zur Verfügung steht. Somit können die induzierten Lichtstrahlen nicht mehr zwischen den Flächen reflektiert werden, sodass die Entstehung eines Lasereffekts unterbunden ist. Mit anderen Worten, durch diese Maßnahme wird die Laserschwelle auf ein mit dem Bezugszeichen 8neu gekennzeichnetes höheres Niveau angehoben, sodass das Ziel erreicht ist, Licht mit einem Breitbandspektrum und mit hoher Intensität zu erzeugen. Fig. 2b illustrates the effect of the light source shown in Fig. 1 with the higher light intensity, wherein as already described a second pair of contacts 5a and 5b is provided, which by a gap 6 from the first pair of contacts 4a and 4b spaced and thus galvanically separated from this is. The effect caused by the electrical conductor 7 galvanic short circuit of the contact pair 5a, 5b causes the light exit surface 1a opposite surface is no longer available as an internal reflection surface available. Thus, the induced light beams can no longer be reflected between the surfaces, so that the formation of a laser effect is prevented. In other words, by this measure, the laser threshold is raised to a higher level denoted by reference numeral 8new so that the goal is achieved of generating light with a broadband spectrum and high intensity.

Claims

Patentansprüche claims
1. Monolithische Miniatur-Breitband-Lichtquelle mit einer Lichtaustrittsfläche (1a), wobei A monolithic miniature broadband light source having a light exit surface (1a), wherein
- ein mittels eines Metal-Organic-Vapour-Phase-Epitaxy-Prozesses oder eines Sputter-Prozesses erzeugter InGaAsP-Halbleiter (1 ) zwischen einem p-lnP- Halbleiter (2) und einem n-lnP-Halbleiter (3) eingebettet ist,  an InGaAsP semiconductor (1) produced by means of a Metal Organic Vapor Phase Epitaxy process or a sputtering process is embedded between a p-type InP semiconductor (2) and an n-type InP semiconductor (3),
- der InGaAsP-Halbleiter (1 ), der p-lnP-Halbleiter (2) und der n-lnP-Halbleiter (3) eine Längserstreckung (L) aufweisen,  the InGaAsP semiconductor (1), the p-type InP semiconductor (2) and the n-type InP semiconductor (3) have a longitudinal extent (L),
- der p-lnP-Halbleiter (2) und der n-lnP-Halbleiter (3) mit paarig angeordneten metallischen Flächenkontakten (4a, 4b und 5a, 5b) versehen sind, wobei  - The p-InP semiconductor (2) and the n-type InP semiconductor (3) with paired metallic surface contacts (4a, 4b and 5a, 5b) are provided, wherein
- ein erstes Kontaktpaar (4a, 4b) sich über wenigstens 60 % der Länge (L) des p- InP-Halbleiters (2) und des n-lnP-Halbleiters (3) erstreckt,  a first contact pair (4a, 4b) extends over at least 60% of the length (L) of the p-InP semiconductor (2) and the n-InP semiconductor (3),
- das erste Kontaktpaar (4a, 4b) und ein zweites Kontaktpaar (5a, 5b) durch einen Spalt (6) galvanisch voneinander getrennt sind und  - The first pair of contacts (4a, 4b) and a second pair of contacts (5a, 5b) by a gap (6) are electrically isolated from each other and
- die Kontaktflächen des zweiten Kontaktpaares (5a, 5b) über einen elektrischen Leiter (7) galvanisch miteinander verbunden sind.  - The contact surfaces of the second contact pair (5a, 5b) via an electrical conductor (7) are electrically connected to each other.
2. Monolithische Miniatur-Breitband-Lichtquelle nach Anspruch 1 , wobei das erste Kontaktpaar (4a, 4b) sich über wenigstens 80 % der Länge (L) des p-lnP-Halblei- ters (2) und des n-lnP-Halbleiters (3) erstreckt, 2. A miniature monolithic broadband light source according to claim 1, wherein the first contact pair (4a, 4b) covers at least 80% of the length (L) of the p-InP semiconductor (2) and the n-InP semiconductor ( 3) extends,
3. Monolithische Miniatur-Breitband-Lichtquelle nach Anspruch 1 oder 2, wobei ein erster Kontakt (4a) des ersten Kontaktpaars (4a, 4b) und ein erster Kontakt (5a) des zweiten Kontaktpaars (5a, 5b) auf gleichem elektrischem Potenzial liegen. The monolithic miniature broadband light source according to claim 1 or 2, wherein a first contact (4a) of the first contact pair (4a, 4b) and a first contact (5a) of the second contact pair (5a, 5b) are at the same electric potential.
PCT/DE2015/000117 2014-03-13 2015-03-13 Monolithic miniature broadband light source for measurements by means of fbg strain sensors WO2015135524A1 (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2669718A1 (en) 2012-06-01 2013-12-04 Heraeus Materials Technology GmbH & Co. KG Light absorbing layer structure

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2669718A1 (en) 2012-06-01 2013-12-04 Heraeus Materials Technology GmbH & Co. KG Light absorbing layer structure

Non-Patent Citations (3)

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Title
KWONG N S K ET AL: "HIGH-POWER 1.3 M SUPERLUMINESCENT DIODE", APPLIED PHYSICS LETTERS, AMERICAN INSTITUTE OF PHYSICS, US, vol. 54, no. 4, 23 January 1989 (1989-01-23), pages 298 - 300, XP000026004, ISSN: 0003-6951, DOI: 10.1063/1.100992 *
NIKITA PIKHTIN ET AL: "High power broadband singlelobe InGaAsP/InP superluminescent diode", 7TH INTERNATIONAL SYMPOSIUM "NANOSTRUCTURES: PHYSICS AND TECHNOLOGY", 31 December 1999 (1999-12-31), pages 150 - 153, XP055208885 *
OOMURA E ET AL: "INGAASP/INP BURIED CRESCENT LASER DIODE EMITTING AT 1.3 MUM WAVELENGTH", IEEE JOURNAL OF QUANTUM ELECTRONICS, IEEE SERVICE CENTER, PISCATAWAY, NJ, USA, vol. QE-20, no. 8, 1 August 1984 (1984-08-01), pages 866 - 873, XP000705671, ISSN: 0018-9197, DOI: 10.1109/JQE.1984.1072495 *

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