EP1232550A1 - Semiconductor optical amplifier - Google Patents

Semiconductor optical amplifier

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Publication number
EP1232550A1
EP1232550A1 EP01963110A EP01963110A EP1232550A1 EP 1232550 A1 EP1232550 A1 EP 1232550A1 EP 01963110 A EP01963110 A EP 01963110A EP 01963110 A EP01963110 A EP 01963110A EP 1232550 A1 EP1232550 A1 EP 1232550A1
Authority
EP
European Patent Office
Prior art keywords
sections
different
active
guiding structure
mode
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP01963110A
Other languages
German (de)
French (fr)
Inventor
Léon Goldstein
Jean-Yves Emery
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Oclaro North America Inc
Original Assignee
Alcatel CIT SA
Alcatel SA
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 Alcatel CIT SA, Alcatel SA filed Critical Alcatel CIT SA
Publication of EP1232550A1 publication Critical patent/EP1232550A1/en
Withdrawn legal-status Critical Current

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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
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • 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
    • H01S5/50—Amplifier structures not provided for in groups H01S5/02 - H01S5/30
    • H01S5/5009—Amplifier structures not provided for in groups H01S5/02 - H01S5/30 the arrangement being polarisation-insensitive
    • 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
    • H01S2301/00—Functional characteristics
    • H01S2301/14—Semiconductor lasers with special structural design for lasing in a specific polarisation mode
    • 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
    • H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
    • H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
    • H01S5/0625—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in multi-section lasers
    • 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
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/1053—Comprising an active region having a varying composition or cross-section in a specific direction
    • H01S5/1064—Comprising an active region having a varying composition or cross-section in a specific direction varying width along the optical axis
    • 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
    • H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
    • H01S5/1082—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region with a special facet structure, e.g. structured, non planar, oblique
    • H01S5/1085—Oblique facets

Definitions

  • the present invention relates to the amplification of optical signals. It typically finds application in fiber optic telecommunications networks.
  • the signals transmitted by these networks consist of pulses carrying in binary form information to be transmitted. These pulses must be amplified to compensate for losses of power which they undergo during their propagation in these networks.
  • Semiconductor amplifiers constitute a space-saving and integrable means to achieve this amplification. However, in the absence of special provisions, their gain is sensitive to the state of polarization of the light they receive, which will be more simply indicated below by mentioning the sensitivity of an amplifier to polarization.
  • this invention finds an application whenever the sensitivity of an optical amplifier to polarization must be zero or limited.
  • the invention applies more specifically to so-called “buried ribbon” amplifiers, known under the term of BRS (for Burried Ridge Structure in English).
  • such a semiconductor optical amplifier (an illustration of which is given in FIG. 1) comprises a wafer 2 made up of layers of semiconductor materials having respective refractive indices and forming a common crystal lattice.
  • networks formed respectively by these materials have characteristic dimensions constituting respective meshes of these materials.
  • These layers follow one another in a vertical direction DV forming a trirectangle trihedron with two horizontal directions constituting a longitudinal direction DL and a transverse direction DT, these directions being defined with respect to this plate 2.
  • These layers form a succession in an ascending direction of the vertical direction DV from a lower face 4 to an upper face 6.
  • This plate 2 comprises at least the following layers or groups of layers or part of a layer:
  • a substrate 8 consisting mainly of a semiconductor base material having a first type of conductivity. This substrate has a sufficient thickness to impose the dimensions of the mesh of the base material on the entire crystal lattice of the wafer 2.
  • An active layer 10 including an active material capable of amplifying light by stimulated recombination of charge carriers of the two types injected into this material.
  • a guiding structure 12 comprising at least one buried ribbon having a higher refractive index than that of surrounding materials.
  • the strip 12 extends in the longitudinal direction DL to guide said light in this direction.
  • This ribbon 12 has a width 1 and a thickness e respectively transverse and vertical.
  • an upper confinement layer 18 made of a material having a second type of conductivity opposite to the first.
  • This amplifier further comprises a lower electrode 20 and an upper electrode 22 respectively formed on the lower face 4 and the upper face 6 of the wafer 2. to allow to pass between these faces an electric current injecting said carrier • charging of two types in the active material.
  • the basic materials of known semiconductor optical amplifiers are of the III-V type. Those are typically indium phosphide and gallium arsenide. Their active material is typically a ternary or quaternary material formed with the same chemical elements. It is generally desired that the width 1 of the ribbon 12 which guides the lights be close to a micrometer to facilitate the formation of this ribbon by etching and above all to facilitate the integration of the amplifier with other optical components on the same semiconductor wafer. The thickness e must then be much less than this width to ensure a mononodal guidance of the light whose wavelength is typically 1310 or 1550 nm. In the absence of special provisions, it is this rectangular shape of the section of the tape 12 which tends to cause the sensitivity to polarization previously mentioned.
  • the active material constituting the light-guiding ribbon 12 is surrounded on all sides by a binary semiconductor material 14, 16.
  • the latter has the advantage of conducting heat well, but its index of refraction is only slightly lower than that of the active material.
  • the active material is homogeneous and is then said to be mass (or bulk material in English).
  • the section of the buried ribbon 12 is strongly rectangular. Given the small difference in index between this ribbon 12 and the surrounding binary material 14, 16. The confinement of a wave with horizontal polarization is greater than that of a wave with vertical polarization, the difference between these two confinements being all the greater the greater the ratio of the width 1 to the thickness e of the strip.
  • the confinement mentioned here in connection with a wave is considered in a transverse plane. It is the ratio of the power of the wave passing through the area occupied by the strip 12 to the total power of 'this wave.
  • the confinement is defined for each polarization and for each wavelength by the shape and the dimensions of the section of the ribbon and by the refractive indices of the material of this ribbon and of the surrounding material. In the case of a rectangular ribbon section, it can be considered to be the product of a directional confinement in the horizontal direction by a directional confinement in the vertical direction, each of these two directional confinements depending on the polarization.
  • the gain of the amplifier for a wave the greater the confinement of this wave. It follows that, if the ribbon material were a homogeneous material, and moreover isotropic, therefore insensitive to polarization, the gain of the amplifier would be greater for the waves with horizontal polarization and than for those with vertical polarization.
  • Such an amplifier has a low sensitivity to polarization.
  • the object of the present invention is to solve the drawbacks of the technology proposed in the aforementioned patent US 5,982,531.
  • the present invention provides a structure such that the sensitivity to the polarization of the overall gain ⁇ G of the amplifier is easily controlled by current for an adjustment of this so-called “active” sensitivity.
  • the optical amplifier according to the invention thus has at least two separate sections, each provided with an electrode, each section having a different geometry and / or voltage stress. so as to favor respectively a higher gain of the TE mode and of the TM mode.
  • the transition between the two sections is abrupt which induces a non-adiabatic modification of the sizes of the modes propagating in the active layer and causes a reflection of the light waves at the level of this transition.
  • the reflections in an SOA are not acceptable.
  • the production of such a structure requires a step of etching the active layer which must be perfectly controlled as well as a step of epitaxial growth after this etching.
  • a well-controlled etching requires dry etching followed by chemical etching.
  • Such a technique is generally avoided on active materials because it induces surface recombination effects which affect the quality of the active layer.
  • the regrowth step is particularly delicate on a thin active layer.
  • the present invention seeks to resolve these drawbacks by proposing another structure with two sections favoring respectively a higher gain of the TE mode and of the TM mode for an “active” adjustment.
  • the structure proposed by the invention consists in making two sections comprising an active layer of the same thickness, but subject to stresses of different tensions and / or having different geometries, while preserving a continuity of the effective indices of refraction of the active layer in the two sections for an adiabatic transition or without index jump.
  • the present invention relates more particularly to a semiconductor optical amplifier comprising at least two amplifier sections each favoring, respectively, a higher gain of the TE mode and of the TM mode of polarization of the light to be amplified, said sections each comprising an active guiding structure having the same thickness, characterized in that the active guiding structure of the two sections is respectively subjected to different tension stresses and / or has a different geometry so as to make the overall gain of the amplifier insensitive to the polarization of said light at amplify, and in that the transition between the different sections presents a continuity of the effective indices of refraction.
  • the active guiding structure of the different sections has a different respective width.
  • the active guiding structure of at least one of the sections has a curvature.
  • the active guiding structure of the different sections is subjected to different respective tension stresses.
  • the active guiding structure is composed of a material having different stoichiometric ratios between the elements making up said material for the different sections.
  • the material of the active guiding structures consists of a quaternary material.
  • the quaternary material is InGaAsP.
  • Figure 1 already described, illustrates schematically ent a buried ribbon amplifier produced according to the prior art
  • Figure 2 is a schematic top view of an amplifier according to a first embodiment of the invention
  • Figure 3 is a schematic top view of an amplifier according to a second embodiment of the invention
  • Figure 4 is a schematic top view of an amplifier according to a third embodiment of the invention.
  • the invention consists in producing an optical amplifier whose gain is independent of the polarization of the light to be amplified.
  • the amplifier comprises two amplifier sections 30 and 40 each favoring, respectively, a higher gain of the TE mode and of the TM mode of polarization of the light to be amplified, each section 30 and 40 being respectively controlled by an electrode. separate 23 and 24.
  • the amplifier comprises a single active guiding structure 12 consisting of an engraved and buried ribbon.
  • This tape 12 is common to the different sections 30 and 40 and has the same thickness everywhere.
  • the material constituting the guiding active structure is a quaternary material such as InGaAsP for example.
  • the guiding active structure 12 nevertheless has specific features specific to each section 30 and 40 making it possible to favor one or the other polarization mode of the light to be amplified.
  • the structure - active guide 12 has a different width li, 1 2 for each section 30 and 40.
  • the confinement of the widest portion of tape will favor the TE propagation mode. while confining the narrowest portion of tape will favor the TM propagation mode.
  • Such a tape 12 can easily be produced by etching with a suitable mask which defines the respective widths of each section 30 and 40.
  • the width l ⁇ of the active guiding structure 12 of section 30 promoting a higher gain of the TE mode is between 0.8 and 1.2 ⁇ m
  • the width 1 2 of the active guiding structure 12 of section 40 favoring a higher gain of the TM mode is between 0.6 and 1.0 ⁇ m, with the condition l ⁇ > l 2 always fulfilled.
  • the active guiding structure 12 has a curvature 13 on the section 30 favoring the TE mode of propagation of the light to be amplified.
  • the material of the active guiding structure is the same on the two sections 30 and 40, as well as its confinement.
  • the curved section 13 of the ribbon 12 will favor the TE mode of light propagation while the straight sections will favor the TM mode (by the nature of the material constituting the ribbon).
  • the straight ribbon sections 40 are separated by the curved section 13, in the example illustrated, but are electrically connected by electrodes 24, 24 'connected to each other.
  • Such a ribbon 12 with a curvature 13 can easily be produced by etching with a suitable mask.
  • an adiabatic transition of the modes between the two sections 30 and 40 is obtained, which eliminates the risks of reflection of the light waves.
  • the active guiding structure 12 is subjected to different respective tension stresses on the different sections 30 and 40.
  • the active guiding structure 12 is composed of a quaternary material.
  • the difference in tension stress between the two sections 30 and 40 is obtained by a difference between the stoichiometric ratios of the elements constituting the material of said active structure 12.
  • the use of the same material (InGaAsP) makes it possible to avoid jumps index from section to section and consequently the light wave reflections between these sections 30 and 40. It is the composition of this material which varies.
  • the ribbon 12 is produced by a double epitaxy for each section according to the known and mastered technique of "butt-coupling".

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

Abstract

The invention concerns a semiconductor optical amplifier comprising at least two amplifying sections (30, 40), each providing, respectively, a higher gain of the TE mode and of the TM mode of the polarisation of the light to be amplified, said sections including each an active guide structure (12) having the same thickness (e). The invention is characterised in that the active guide structure (12) of the two sections (30, 40) is respectively subjected to strains of different tension and/or has a different geometrical shape so as to make the global gain of the amplifier insensitive to the polarisation of said light to be amplified, and the transition between the different sections (30, 40) has continuity of effective refraction indices.

Description

AMPLIFICATEUR OPTIQUE A SEMI-CONDUCTEUR SEMICONDUCTOR OPTICAL AMPLIFIER
La présente invention concerne l'amplification de signaux optiques. Elle trouve typiquement application dans les réseaux de télécommunications à fibres optiques. Les signaux transmis par ces réseaux sont constitués d'impulsions portant sous forme binaire une information à transmettre. Ces impulsions doivent être amplifiées pour compenser des pertes de puissance qu'elles subissent au cours de leur propagation dans ces réseaux. Les amplificateurs à semi-conducteurs constituent un moyen peu encombrant et intégrable pour réaliser cette amplification. Cependant, en l'absence de dispositions particulières, leur gain est sensible à l'état de polarisation de la lumière qu'ils reçoivent, ce qui sera plus simplement indiquée ci-après en mentionnant la sensibilité d'un amplificateur à la polarisation.The present invention relates to the amplification of optical signals. It typically finds application in fiber optic telecommunications networks. The signals transmitted by these networks consist of pulses carrying in binary form information to be transmitted. These pulses must be amplified to compensate for losses of power which they undergo during their propagation in these networks. Semiconductor amplifiers constitute a space-saving and integrable means to achieve this amplification. However, in the absence of special provisions, their gain is sensitive to the state of polarization of the light they receive, which will be more simply indicated below by mentioning the sensitivity of an amplifier to polarization.
Cette invention trouve alors plus particulièrement application dans le cas où il convient de supprimer ou du moins de limiter cette sensibilité, qui peut s'exprimer par l'équation suivante : ΔG=GTE-GTM. On cherche à atteindre |ΔG|< ldB.This invention then finds more particularly application in the case where it is advisable to suppress or at least to limit this sensitivity, which can be expressed by the following equation: ΔG = G TE -G TM . We are trying to reach | ΔG | <ldB.
Le cas où la sensibilité doit être limitée ou supprimée est fréquent et apparaît, d'une part lorsque la distance parcourue par les impulsions optiques à amplifier est telle que l'état de polarisation de ces impulsions a été affecté d'une manière importante et aléatoire au cours de leur propagation et, d'autre part lorsqu'il est préférable que les impulsions amplifiées présentent un ou plusieurs niveaux de puissance prédéterminés . De manière plus générale cette invention trouve une application chaque fois que la sensibilité d'un amplificateur optique à la polarisation doit être nulle ou limitée.The case where the sensitivity must be limited or suppressed is frequent and appears, on the one hand when the distance traveled by the optical pulses to be amplified is such that the state of polarization of these pulses has been significantly affected and random during their propagation and, on the other hand when it is preferable that the amplified pulses have one or more predetermined power levels. More generally, this invention finds an application whenever the sensitivity of an optical amplifier to polarization must be zero or limited.
L'invention s'applique plus spécifiquement à des amplificateurs dits à « ruban enterré », connu sous le terme de BRS (pour Burried Ridge Structure en anglais) .The invention applies more specifically to so-called “buried ribbon” amplifiers, known under the term of BRS (for Burried Ridge Structure in English).
On sait qu'un tel amplificateur optique à semiconducteur (dont une illustration est donnée sur la figure 1) comporte une plaquette 2 constituée de couches de matériaux semi-conducteurs ayant des indices de réfraction respectifs et formant un réseau cristallin commun. En l'absence de contraintes mécaniques, des réseaux formés respectivement par ces matériaux ont des dimensions caractéristiques constituant des mailles respectives de ces matériaux. Ces couches se succèdent selon une direction verticale DV formant un trièdre trirectangle avec deux directions horizontales constituant une direction longitudinale DL et une direction transversale DT, ces directions étant définies par rapport à cette plaquette 2. Ces couches forment une succession dans un sens ascendant de la direction verticale DV d'une face inférieure 4 à une face supérieure 6. Cette plaquette 2 comporte au moins les couches ou groupes de couches ou partie de couche suivants : Un substrat 8 constitué majoritairement d'un matériau de base semi-conducteur ayant un premier type de conductivité. Ce substrat présente une épaisseur suffisante pour imposer les dimensions de la maille du matériau de base à tout le réseau cristallin de la plaquette 2.It is known that such a semiconductor optical amplifier (an illustration of which is given in FIG. 1) comprises a wafer 2 made up of layers of semiconductor materials having respective refractive indices and forming a common crystal lattice. In the absence of mechanical constraints, networks formed respectively by these materials have characteristic dimensions constituting respective meshes of these materials. These layers follow one another in a vertical direction DV forming a trirectangle trihedron with two horizontal directions constituting a longitudinal direction DL and a transverse direction DT, these directions being defined with respect to this plate 2. These layers form a succession in an ascending direction of the vertical direction DV from a lower face 4 to an upper face 6. This plate 2 comprises at least the following layers or groups of layers or part of a layer: A substrate 8 consisting mainly of a semiconductor base material having a first type of conductivity. This substrate has a sufficient thickness to impose the dimensions of the mesh of the base material on the entire crystal lattice of the wafer 2.
Une couche active 10 incluant un matériau actif apte à amplifier une lumière par recombinaison stimulée de porteurs - de charges des deux types injectés dans ce matériau.An active layer 10 including an active material capable of amplifying light by stimulated recombination of charge carriers of the two types injected into this material.
Une structure guidante 12 comportant au moins un ruban enterré présentant un indice de réfraction plus grand que celui de matériaux environnants. Le ruban 12 s'étend selon la direction longitudinale DL pour guider ladite lumière selon cette direction. Ce ruban 12 présente une largeur 1 et une épaisseur e respectivement transversale et verticale.A guiding structure 12 comprising at least one buried ribbon having a higher refractive index than that of surrounding materials. The strip 12 extends in the longitudinal direction DL to guide said light in this direction. This ribbon 12 has a width 1 and a thickness e respectively transverse and vertical.
Enfin une couche de confinement supérieure 18 constituée d'un matériau ayant un deuxième type de conductivité opposé au premier.Finally, an upper confinement layer 18 made of a material having a second type of conductivity opposite to the first.
Cet amplificateur comporte en outre une électrode inférieure 20 et une électrode supérieure 22 respectivement formées sur la face inférieure 4 et la face supérieure 6 de la plaquette 2. pour permettre de faire passer entre ces faces un courant électrique injectant lesdits porteurs • de charge des deux types dans le matériau actif.This amplifier further comprises a lower electrode 20 and an upper electrode 22 respectively formed on the lower face 4 and the upper face 6 of the wafer 2. to allow to pass between these faces an electric current injecting said carrier • charging of two types in the active material.
Les matériaux de base des amplificateurs optiques à semi-conducteurs connus sont du type III-V. Ce sont typiquement le phosphure d' indium et l'arséniure de gallium. Leur matériau actif est typiquement un matériau ternaire ou quaternaire constitué avec les mêmes éléments chimiques. Il est généralement souhaité que la largeur 1 du ruban 12 qui guide la lumières soit voisine d'un micromètre pour faciliter la formation de ce ruban par gravure et surtout pour faciliter l'intégration de l'amplificateur avec d'autres composants optiques sur une même plaquette semi- conductrice. L'épaisseur e doit alors être très inférieure à cette largeur pour assurer un guidage mononodal de la lumière dont la longueur d'onde est typiquement 1310 ou 1550 nm. En l'absence de dispositions particulières c' est cette forme rectangulaire de la section du ruban 12 qui tend à entraîner la sensibilité à la polarisation précédemment mentionnée .The basic materials of known semiconductor optical amplifiers are of the III-V type. Those are typically indium phosphide and gallium arsenide. Their active material is typically a ternary or quaternary material formed with the same chemical elements. It is generally desired that the width 1 of the ribbon 12 which guides the lights be close to a micrometer to facilitate the formation of this ribbon by etching and above all to facilitate the integration of the amplifier with other optical components on the same semiconductor wafer. The thickness e must then be much less than this width to ensure a mononodal guidance of the light whose wavelength is typically 1310 or 1550 nm. In the absence of special provisions, it is this rectangular shape of the section of the tape 12 which tends to cause the sensitivity to polarization previously mentioned.
Dans les amplificateurs à ruban enterré, ou BRS, le matériau actif constituant le ruban 12 guidant la lumière est entouré de toutes parts par un matériau semi-conducteur binaire 14, 16. Ce dernier présente l'avantage de bien conduire la chaleur mais son indice de réfraction n'est que légèrement inférieur à celui du matériau actif. On considère en outre le cas où le matériau actif est homogène et est alors dit massique (ou bulk material en anglais) . En général, la section du ruban enterré 12 est fortement rectangulaire. Compte tenu de la faible différence d' indice entre ce ruban 12 et le matériau binaire environnant 14, 16. Le confinement d'une onde à polarisation horizontale est supérieur à celui d'une onde à polarisation verticale, la différence entre ces deux confinements étant d' autant plus grande que le rapport de la largeur 1 à l'épaisseur e du ruban est grand. Le confinement mentionné ici à propos d'une onde est considéré dans un plan transversal. Il est égal au rapport de la puissance de cette onde transitant dans l'aire occupée par le ruban 12 à la puissance totale de' cette onde. Le confinement est défini pour chaque polarisation et pour chaque longueur d'onde par la forme et les dimensions de la section du ruban et par les indices de réfraction du matériau de ce ruban et du matériau environnant. Dans le cas d'une section de ruban rectangulaire il peut être considéré comme étant le produit d'un confinement directionnel selon la direction horizontale par un confinement directionnel selon la direction verticale, chacun de ces deux confinements directionnels dépendant de la polarisation. Compte tenu du fait que le phénomène d'amplification de l'onde par recombinaison de porteurs et émission stimulée n'est réalisée que dans le matériau actif, c'est à dire dans le ruban 12, le gain de l'amplificateur pour une onde est d'autant plus grand que le confinement de cette onde est plus grand. Il est résulte que, si le matériau du ruban était un matériau homogène, et de plus isotrope, donc insensible à la polarisation, le gain de l'amplificateur serait plus grand pour les ondes à polarisation horizontale et que pour celles à polarisation verticale.In buried ribbon amplifiers, or BRS, the active material constituting the light-guiding ribbon 12 is surrounded on all sides by a binary semiconductor material 14, 16. The latter has the advantage of conducting heat well, but its index of refraction is only slightly lower than that of the active material. We also consider the case where the active material is homogeneous and is then said to be mass (or bulk material in English). In general, the section of the buried ribbon 12 is strongly rectangular. Given the small difference in index between this ribbon 12 and the surrounding binary material 14, 16. The confinement of a wave with horizontal polarization is greater than that of a wave with vertical polarization, the difference between these two confinements being all the greater the greater the ratio of the width 1 to the thickness e of the strip. The confinement mentioned here in connection with a wave is considered in a transverse plane. It is the ratio of the power of the wave passing through the area occupied by the strip 12 to the total power of 'this wave. The confinement is defined for each polarization and for each wavelength by the shape and the dimensions of the section of the ribbon and by the refractive indices of the material of this ribbon and of the surrounding material. In the case of a rectangular ribbon section, it can be considered to be the product of a directional confinement in the horizontal direction by a directional confinement in the vertical direction, each of these two directional confinements depending on the polarization. Given the fact that the phenomenon of amplification of the wave by recombination of carriers and stimulated emission is carried out only in the active material, that is to say in the ribbon 12, the gain of the amplifier for a wave the greater the confinement of this wave. It follows that, if the ribbon material were a homogeneous material, and moreover isotropic, therefore insensitive to polarization, the gain of the amplifier would be greater for the waves with horizontal polarization and than for those with vertical polarization.
Plusieurs recherches ont été effectuées dans l'art antérieur pour rendre ces amplificateurs insensibles à la polarisation de la lumière à amplifier. En particulier, le brevet américain US 5 982 531, du déposant, propose un tel amplificateur rendu insensible à la polarisation de la lumière. Cet amplificateur est caractérisé par le fait que son matériau actif est soumis à une contrainte de tension suffisante pour rendre son gain insensible à la polarisation de ladite lumière à amplifier. Cette contrainte résulte généralement d'un désaccord de maille entre le matériau actif et le matériau de base. Typiquement le confinement horizontal est égal au produit du confinement vertical par un coefficient de dissymétrie de confinement.Several researches have been carried out in the prior art to make these amplifiers insensitive to the polarization of the light to be amplified. In particular, American patent US Pat. No. 5,982,531, proposes such an amplifier made insensitive to the polarization of light. This amplifier is characterized in that its active material is subjected to a voltage stress sufficient to render its gain insensitive to the polarization of said light to be amplified. This constraint generally results from a mesh mismatch between the active material and the base material. Typically horizontal confinement is equal to the product of vertical confinement by a coefficient of asymmetry of confinement.
Cette demande de brevet est basée sur l'observation que, "même en présence d'un coefficient de dissymétrie de confinement élevé résultant, par exemple, du fait que la structure guidante est constituée par un ruban à section fortement rectangulaire, la contrainte de tension à appliquer à un matériau actif homogène formant ce ruban pour obtenir l'insensibilité à la polarisation est suffisamment faible pour que l'épaisseur de ce ruban reste inférieure à l'épaisseur critique correspondante relative aux dislocations.This patent application is based on the observation that, " even in the presence of a high coefficient of asymmetry of confinement resulting, for example, from the fact that the guiding structure is constituted by a tape with a strongly rectangular section, the tension stress to be applied to a homogeneous active material forming this ribbon to obtain insensitivity to polarization is sufficiently low so that the thickness of this ribbon remains less than the corresponding critical thickness relating to dislocations.
Un tel amplificateur présente une faible sensibilité à la polarisation. Les principaux paramètres d'un tel amplificateur sont : longueur d'onde de la couche active amplificatrice : λ=l,57 μm, matériau actif : Inι_xGaxPι-yASy contrainte en tension de la . couche active : Δa/a=-0,015 épaisseur de la couche active : e = 0, 2 μm largeur de ruban 1 = lμSuch an amplifier has a low sensitivity to polarization. The main parameters of such an amplifier are: wavelength of the active amplifier layer: λ = 1.57 μm, active material: Inι_ x Ga x Pι-yASy voltage stress of the. active layer: Δa / a = -0.015 thickness of the active layer: e = 0.2 μm width of tape 1 = lμ
Une telle structure présente néanmoins des inconvénients. Il a en effet été établi, expérimentalement et théoriquement, que la polarisation dépendait fortement du contrôle de l'épaisseur de la couche active ainsi que des contraintes auxquelles elle est soumise. Par exemple, une modification de cette contrainte (Δa/a) de -0,015 à 0,014 ou -0,016 induit un décalage du gain ΔG de 0,8dB vers une sensibilité respective du mode TE ou du mode TM. De même, une légère modification de quelques pourcents de l'épaisseur de la couche active induit directement un décalage du gain ΔG de l'ampli. Ainsi, la sensibilité à la polarisation de la lumière de l'amplificateur dépend de sa structure et ne peut pas être facilement contrôlée.Such a structure nevertheless has drawbacks. It has indeed been established, experimentally and theoretically, that the polarization strongly depends on the control of the thickness of the active layer as well as the constraints to which it is subjected. For example, a modification of this constraint (Δa / a) from -0.015 to 0.014 or -0.016 induces a shift in the gain ΔG of 0.8dB towards a respective sensitivity of TE mode or TM mode. Similarly, a slight change of a few percent in the thickness of the active layer directly induces a shift in the gain ΔG of the amplifier. Thus, the sensitivity to light polarization of the amplifier depends on its structure and cannot be easily controlled.
L'objet de la présente invention est de résoudre les inconvénients de la technologie proposée dans le brevet précité US 5 982 531.The object of the present invention is to solve the drawbacks of the technology proposed in the aforementioned patent US 5,982,531.
A cet effet, la présente invention propose une structure telle que la sensibilité à la polarisation du gain global ΔG de l'amplificateur soit contrôlée facilement par courant pour un ajustement de cette sensibilité dite « active »To this end, the present invention provides a structure such that the sensitivity to the polarization of the overall gain ΔG of the amplifier is easily controlled by current for an adjustment of this so-called “active” sensitivity.
L'amplificateur optique selon l'invention présente ainsi au moins deux sections distinctes munies chacune d'une électrode, chaque section présentant une géométrie et/ou une contrainte en tension différentes de manière à favoriser respectivement un gain plus élevé du mode TE et du mode TM.The optical amplifier according to the invention thus has at least two separate sections, each provided with an electrode, each section having a different geometry and / or voltage stress. so as to favor respectively a higher gain of the TE mode and of the TM mode.
Une telle structure à deux sections a déjà été proposée, en particulier dans la demande de brevet japonais JP 10154841. Cette demande de brevet explore une solution consistant à faire varier l'épaisseur de la couche active d'une section à l'autre de manière à influer sur le gain en favorisant respectivement le mode TE avec une faible épaisseur puis le. mode TM avec une épaisseur plus importante.Such a structure with two sections has already been proposed, in particular in Japanese patent application JP 10154841. This patent application explores a solution consisting in varying the thickness of the active layer from one section to another so to influence the gain by respectively favoring the TE mode with a small thickness then the. TM mode with greater thickness.
Par un ajustement des courants injectés sur chaque électrode de chaque section, les gains des deux sections peuvent être ajustés de manière à obtenir un amplificateur indépendant de la polarisation. Néanmoins, la solution proposée par cette demande de brevet japonais présente des inconvénients, en particulier sur le plan de la réalisation technique.By adjusting the currents injected on each electrode of each section, the gains of the two sections can be adjusted so as to obtain an amplifier independent of the polarization. However, the solution proposed by this Japanese patent application has drawbacks, in particular in terms of technical implementation.
D'une part, la transition entre les deux sections est abrupte ce qui induit une modification non adiabatique des tailles des modes se propageant dans la couche active et provoque une réflexion des ondes lumineuses au niveau de cette transition. Or, les réflexions dans un SOA ne sont pas acceptables.On the one hand, the transition between the two sections is abrupt which induces a non-adiabatic modification of the sizes of the modes propagating in the active layer and causes a reflection of the light waves at the level of this transition. However, the reflections in an SOA are not acceptable.
D'autre part, la réalisation d'une telle structure nécessite une étape de gravure de la couche active qui doit être parfaitement contrôlée ainsi qu'une étape de croissance épitaxiale après cette gravure. Or, une gravure bien contrôlée nécessite une gravure sèche suivie d'une gravure chimique. Une telle technique est généralement évitée sur des matériaux actifs car elle induit des effets de recombinaison en surface qui nuisent à la qualité de la couche active. En outre, l'étape de recroissance est particulièrement délicate sur une couche active fine.On the other hand, the production of such a structure requires a step of etching the active layer which must be perfectly controlled as well as a step of epitaxial growth after this etching. However, a well-controlled etching requires dry etching followed by chemical etching. Such a technique is generally avoided on active materials because it induces surface recombination effects which affect the quality of the active layer. In addition, the regrowth step is particularly delicate on a thin active layer.
La présente invention cherche à résoudre ces inconvénients en proposant une autre structure à deux sections favorisant respectivement un gain plus élevé du mode TE et du mode TM pour un ajustement « actif ».The present invention seeks to resolve these drawbacks by proposing another structure with two sections favoring respectively a higher gain of the TE mode and of the TM mode for an “active” adjustment.
La structure proposée par l'invention consiste à réaliser deux sections comportant une couche active de même épaisseur, mais soumises à des contraintes de tensions différentes et/ou présentant des géométries différentes, tout en conservant une continuité des indices effectifs de réfraction de la couche active dans les deux sections pour une transition adiabatique ou sans saut d'indice.The structure proposed by the invention consists in making two sections comprising an active layer of the same thickness, but subject to stresses of different tensions and / or having different geometries, while preserving a continuity of the effective indices of refraction of the active layer in the two sections for an adiabatic transition or without index jump.
La présente invention concerne plus particulièrement un amplificateur optique à semiconducteur comportant au moins deux sections amplificatrices favorisant chacune, respectivement, un gain plus élevé du mode TE et du mode TM de polarisation de la lumière à amplifier, lesdites section comprenant chacune une structure active guidante présentant la même épaisseur, caractérisé en ce que la structure active guidante des deux sections est respectivement soumise à des contraintes de tension différentes et/ou présente une géométrie différente de manière à rendre le gain global de l'amplificateur insensible à la polarisation de ladite lumière à amplifier, et en ce que la transition entre les différentes sections présente une continuité des indices effectifs de réfraction. Selon un premier mode de réalisation, la structure active guidante des différentes sections présente une largeur respective différente.The present invention relates more particularly to a semiconductor optical amplifier comprising at least two amplifier sections each favoring, respectively, a higher gain of the TE mode and of the TM mode of polarization of the light to be amplified, said sections each comprising an active guiding structure having the same thickness, characterized in that the active guiding structure of the two sections is respectively subjected to different tension stresses and / or has a different geometry so as to make the overall gain of the amplifier insensitive to the polarization of said light at amplify, and in that the transition between the different sections presents a continuity of the effective indices of refraction. According to a first embodiment, the active guiding structure of the different sections has a different respective width.
Selon un deuxième mode de réalisation, la structure active guidante d' au moins une des sections présente une courbure .According to a second embodiment, the active guiding structure of at least one of the sections has a curvature.
Selon un troisième mode de réalisation, la structure active guidante des différentes sections est soumise à des contraintes de tension respectives différentes.According to a third embodiment, the active guiding structure of the different sections is subjected to different respective tension stresses.
Selon une particularité du troisième mode de réalisation, la structure active guidante est composée d'un matériau présentant des rapports stoechiométriques différents entre les éléments composant ledit matériau pour les différentes sections.According to a feature of the third embodiment, the active guiding structure is composed of a material having different stoichiometric ratios between the elements making up said material for the different sections.
Selon une caractéristique, le matériau des structures actives guidantes est constitué d'un matériau quaternaire.According to one characteristic, the material of the active guiding structures consists of a quaternary material.
Selon une particularité, le matériau quaternaire est de l'InGaAsP.According to one feature, the quaternary material is InGaAsP.
Les particularités et avantages de l'invention apparaîtront clairement à la lecture de la description qui suit, donnée à titre d'exemple illustratif et non limitatif, et faite en référence aux figures annexées dans lesquelles :The features and advantages of the invention will appear clearly on reading the description which follows, given by way of illustrative and nonlimiting example, and made with reference to the appended figures in which:
La figure 1, déjà décrite, illustre schématique ent un amplificateur à ruban enterré réalisé selon l'art antérieur ; - La figure 2 est une vue schématique de dessus d'un amplificateur selon un premier mode de réalisation de l'invention ; La figure 3 est une vue schématique de dessus d'un amplificateur selon un deuxième mode de réalisation de l'invention ;Figure 1, already described, illustrates schematically ent a buried ribbon amplifier produced according to the prior art; - Figure 2 is a schematic top view of an amplifier according to a first embodiment of the invention; Figure 3 is a schematic top view of an amplifier according to a second embodiment of the invention;
La figure 4 est une vue schématique de dessus d'un amplificateur selon un troisième mode de réalisation de l'invention.Figure 4 is a schematic top view of an amplifier according to a third embodiment of the invention.
L'invention consiste à réaliser, un amplificateur optique dont le gain est indépendant de la polarisation de la lumière à amplifier.The invention consists in producing an optical amplifier whose gain is independent of the polarization of the light to be amplified.
Selon l'invention, l'amplificateur comporte deux sections amplificatrices 30 et 40 favorisant chacune, respectivement, un gain plus élevé du mode TE et du mode TM de polarisation de la lumière à amplifier, chaque section 30 et 40 étant respectivement commandée par une électrode distincte 23 et 24.According to the invention, the amplifier comprises two amplifier sections 30 and 40 each favoring, respectively, a higher gain of the TE mode and of the TM mode of polarization of the light to be amplified, each section 30 and 40 being respectively controlled by an electrode. separate 23 and 24.
Ainsi, par un ajustement dit « actif » au moyen du courant injecté sur chaque électrode 23 et 24, il est possible de favoriser l'un ou l'autre mode de polarisation de la lumière à amplifier afin de rendre le gain global de l'amplificateur insensible à cette polarisation. Le courant appliqué doit être suffisant pour éviter les nuisances dues au bruit, sans être trop élevé, ce qui diminuerai les effets de la commande électrique sur la polarisation de la lumière.Thus, by a so-called “active” adjustment by means of the current injected on each electrode 23 and 24, it is possible to favor one or the other mode of polarization of the light to be amplified in order to make the overall gain of the amplifier insensitive to this polarization. The current applied must be sufficient to avoid nuisance due to noise, without being too high, which will reduce the effects of electrical control on the polarization of light.
Selon une particularité de l'invention, l'amplificateur comporte une unique structure active guidante 12 constituée d'un ruban gravé et enterré. Ce ruban 12 est commun aux différentes sections 30 et 40 et présente la même épaisseur partout. Préférentiellement, le matériau constituant la structure active guidante est un matériau quaternaire tel que de l'InGaAsP par exemple.According to a feature of the invention, the amplifier comprises a single active guiding structure 12 consisting of an engraved and buried ribbon. This tape 12 is common to the different sections 30 and 40 and has the same thickness everywhere. Preferably, the material constituting the guiding active structure is a quaternary material such as InGaAsP for example.
La structure active guidante 12 présente néanmoins des particularités propres à chaque section 30 et 40 permettant de favoriser l'un et l'autre mode de polarisation de la lumière à amplifier.The guiding active structure 12 nevertheless has specific features specific to each section 30 and 40 making it possible to favor one or the other polarization mode of the light to be amplified.
Selon un premier mode de réalisation, illustré sur la figure 2, la structure - active guidante 12 présente une largeur différente li, 12 pour chaque section 30 et 40. Le confinement de la portion de ruban la plus large favorisera le mode de propagation TE alors que le confinement de la portion de ruban la plus étroite favorisera le mode de propagation TM. Un tel ruban 12 est aisément réalisable par gravure avec un masque adapté qui définie les largeurs respectives de chaque section 30 et 40.According to a first embodiment, illustrated in FIG. 2, the structure - active guide 12 has a different width li, 1 2 for each section 30 and 40. The confinement of the widest portion of tape will favor the TE propagation mode. while confining the narrowest portion of tape will favor the TM propagation mode. Such a tape 12 can easily be produced by etching with a suitable mask which defines the respective widths of each section 30 and 40.
Selon des exemples de modes de mise en œuvre, la largeur lχ de la structure active guidante 12 de la section 30 favorisant un gain plus élevé du mode TE est comprise entre 0.8 et 1.2 μm, et la largeur 12 de la structure active guidante 12 de la section 40 favorisant un gain plus élevé du mode TM est comprise entre 0.6 et 1.0 μm, avec la condition lι>l2 toujours remplie.According to examples of implementation modes, the width lχ of the active guiding structure 12 of section 30 promoting a higher gain of the TE mode is between 0.8 and 1.2 μm, and the width 1 2 of the active guiding structure 12 of section 40 favoring a higher gain of the TM mode is between 0.6 and 1.0 μm, with the condition lι> l 2 always fulfilled.
Cette différence de largeur du ruban actif 12, contrairement à une différence d'épaisseur, permet une transition adiabatique des modes entre les deux sections 30 et 40, ce qui élimine les risques de réflexion des ondes lumineuses. Selon un deuxième mode de réalisation, illustré sur la figure 3, la structure active guidante 12 présente une courbure 13 sur la section 30 favorisant le mode TE de propagation de la lumière à amplifier. Comme précédemment, le matériau de la structure active guidante est le même sur les deux sections 30 et 40, ainsi que son confinement. La section courbe 13 du ruban 12 va favoriser le mode TE de propagation de la lumière alors que les sections droites vont favoriser le mode TM (de par la nature du matériau constituant le ruban) . Les sections à ruban droit 40 sont séparées par la section courbe 13, dans l'exemple illustré, mais sont électriquement reliées par des électrodes 24, 24' connectées entre elles. Un tel ruban 12 avec une courbure 13 est aisément réalisable par gravure avec un masque adapté. Là encore, on obtient une transition adiabatique des modes entre les deux sections 30 et 40, ce qui élimine les risques de réflexion des ondes lumineuses. Selon un troisième mode de réalisation, illustré sur la figure 4, la structure active guidante 12 est soumise à des contraintes de tension respectives différentes sur les différentes sections 30 et 40.This difference in width of the active strip 12, unlike a difference in thickness, allows an adiabatic transition of the modes between the two sections 30 and 40, which eliminates the risks of reflection of the light waves. According to a second embodiment, illustrated in FIG. 3, the active guiding structure 12 has a curvature 13 on the section 30 favoring the TE mode of propagation of the light to be amplified. As before, the material of the active guiding structure is the same on the two sections 30 and 40, as well as its confinement. The curved section 13 of the ribbon 12 will favor the TE mode of light propagation while the straight sections will favor the TM mode (by the nature of the material constituting the ribbon). The straight ribbon sections 40 are separated by the curved section 13, in the example illustrated, but are electrically connected by electrodes 24, 24 'connected to each other. Such a ribbon 12 with a curvature 13 can easily be produced by etching with a suitable mask. Here again, an adiabatic transition of the modes between the two sections 30 and 40 is obtained, which eliminates the risks of reflection of the light waves. According to a third embodiment, illustrated in FIG. 4, the active guiding structure 12 is subjected to different respective tension stresses on the different sections 30 and 40.
La structure active guidante 12 est composée d'un matériau quaternaire. La différence de contrainte de tension entre les deux sections 30 et 40 est obtenue par une différence entre les rapports stœchiométriques des éléments constituant le matériau de ladite structure active 12. L'utilisation d'un même matériau (InGaAsP) permet d'éviter les sauts d'indice d'une section à l'autre et par conséquent les réflexions d'ondes lumineuses entre ces sections 30 et 40. C'est la composition de ce matériau qui varie.The active guiding structure 12 is composed of a quaternary material. The difference in tension stress between the two sections 30 and 40 is obtained by a difference between the stoichiometric ratios of the elements constituting the material of said active structure 12. The use of the same material (InGaAsP) makes it possible to avoid jumps index from section to section and consequently the light wave reflections between these sections 30 and 40. It is the composition of this material which varies.
Ainsi, pour une longueur d'onde donnée λ de la lumière à .amplifier (1.5 μm, par exemple), plusieurs couples (x, y) sont possibles pour donner des tensions de mailles différentes du matériau Inι-xGax sι-yPy sur chaque section.Thus, for a given wavelength λ of the light to be amplified (1.5 μm, for example), several couples (x, y) are possible to give different mesh voltages of the material Inι- x Ga x sι-yPy on each section.
Le ruban 12 est réalisé par une double épitaxie pour chaque section selon la technique connue et maîtrisée du « butt-coupling ».The ribbon 12 is produced by a double epitaxy for each section according to the known and mastered technique of "butt-coupling".
Les trois modes de réalisation décrits ne sont pas limitatifs, et en particulier, ils peuvent être combinés entre eux sans sortir du cadre de la présente invention. The three embodiments described are not limiting, and in particular, they can be combined with each other without departing from the scope of the present invention.

Claims

REVENDICATIONS
1. Amplificateur optique à semi-conducteur comportant -au moins deux sections amplificatrices (30, 40) favorisant chacune, respectivement, un gain plus élevé du mode TE et du mode TM de .polarisation de la lumière à amplifier, lesdites section comprenant chacune une structure active guidante (12) présentant la même épaisseur (e) , caractérisé en ce que la structure active guidante (12) des deux sections (30, 40) est respectivement soumise à des contraintes de tension différentes et/ou présente une géométrie différente de manière à rendre le gain global de l'amplificateur insensible à la polarisation de ladite lumière à amplifier, et en ce que la transition entre les différentes sections (30, 40) présente une continuité des indices effectifs de réfraction.1. A semiconductor optical amplifier comprising -at least two amplifying sections (30, 40) each promoting, respectively, a higher gain of the TE mode and of the TM mode of .polarization of the light to be amplified, said sections each comprising a active guiding structure (12) having the same thickness (e), characterized in that the active guiding structure (12) of the two sections (30, 40) is respectively subjected to different tension stresses and / or has a geometry different from so as to make the overall gain of the amplifier insensitive to the polarization of said light to be amplified, and in that the transition between the different sections (30, 40) exhibits a continuity of the effective indices of refraction.
2. Amplificateur optique à semi-conducteur selon la revendication 1, caractérisé en ce que la structure active guidante (12) des différentes sections (30, 40) présente une largeur respective différente (li, 12) .2. optical semiconductor amplifier according to claim 1, characterized in that the active guiding structure (12) of the different sections (30, 40) has a different respective width (li, 1 2 ).
3. Amplificateur optique à semi-conducteur selon la revendication 1, caractérisé en ce que la structure active guidante (12) d'au moins une des sections (30) présente une courbure (13) . 3. Semiconductor optical amplifier according to claim 1, characterized in that the active guiding structure (12) of at least one of the sections (30) has a curvature (13).
4. Amplificateur optique à semi-conducteur selon la revendication 1, caractérisé en ce que la structure active guidante (12) des différentes sections (30, 40) est soumise à des contraintes de tension respectives différentes.4. Semiconductor optical amplifier according to claim 1, characterized in that the active guiding structure (12) of the different sections (30, 40) is subjected to different respective voltage stresses.
5. Amplificateur optique à semi-conducteur selon la revendication 2, caractérisé en ce que la largeur (lx) de la structure active guidante (12) de la section (30) favorisant un gain plus élevé du mode TE est comprise entre 0.8 et 1.2 μm.5. Semiconductor optical amplifier according to claim 2, characterized in that the width (l x ) of the active guiding structure (12) of the section (30) favoring a higher gain of the TE mode is between 0.8 and 1.2 μm.
6. Amplificateur optique à semi-conducteur selon la revendication 2, caractérisé en ce que la largeur (12) de la structure active guidante (12) de la section (40) favorisant un gain plus élevé du mode TM est comprise entre 0.6 et 1.0 μm.6. optical semiconductor amplifier according to claim 2, characterized in that the width (1 2 ) of the active guiding structure (12) of the section (40) promoting a higher gain of the TM mode is between 0.6 and 1.0 μm.
7. Amplificateur optique à semi-conducteur selon la revendication 4, caractérisé en ce que la structure active guidante (12) est composée d'un matériau présentant des rapports stœchiométriques différents entre les éléments composant ledit matériau pour les différentes sections (30, 40) .7. A semiconductor optical amplifier according to claim 4, characterized in that the active guiding structure (12) is composed of a material having different stoichiometric ratios between the elements making up said material for the different sections (30, 40) .
8. Amplificateur optique à semi-conducteur selon l'une quelconque des revendications précédentes, caractérisé en ce que le matériau des structures actives guidantes (12) est constitué d'un matériau quaternaire. 8. Semiconductor optical amplifier according to any one of the preceding claims, characterized in that the material of the active guiding structures (12) consists of a quaternary material.
9. Amplificateur optique à semi-conducteur selon la revendication 8, caractérisé en ce que le matériau quaternaire est de l'InGaAsP. 9. A semiconductor optical amplifier according to claim 8, characterized in that the quaternary material is InGaAsP.
EP01963110A 2000-08-22 2001-08-20 Semiconductor optical amplifier Withdrawn EP1232550A1 (en)

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FR0010818A FR2813448A1 (en) 2000-08-22 2000-08-22 SEMICONDUCTOR OPTICAL AMPLIFIER
FR0010818 2000-08-22
PCT/FR2001/002632 WO2002017454A1 (en) 2000-08-22 2001-08-20 Semiconductor optical amplifier

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US20020154391A1 (en) 2002-10-24
FR2813448A1 (en) 2002-03-01
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WO2002017454A1 (en) 2002-02-28
US6751015B2 (en) 2004-06-15
JP2004507894A (en) 2004-03-11

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