EP1155484A1 - Laser source wavelength multiplexer - Google Patents
Laser source wavelength multiplexerInfo
- Publication number
- EP1155484A1 EP1155484A1 EP00993665A EP00993665A EP1155484A1 EP 1155484 A1 EP1155484 A1 EP 1155484A1 EP 00993665 A EP00993665 A EP 00993665A EP 00993665 A EP00993665 A EP 00993665A EP 1155484 A1 EP1155484 A1 EP 1155484A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- beams
- diffraction grating
- laser
- grating
- diffraction
- 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.)
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Classifications
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- 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
- H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
- H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar
- H01S5/4031—Edge-emitting structures
- H01S5/4062—Edge-emitting structures with an external cavity or using internal filters, e.g. Talbot filters
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- 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
- H01S5/12—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 the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
- H01S5/1206—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 the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers having a non constant or multiplicity of periods
- H01S5/1215—Multiplicity of periods
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- 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
- H01S5/14—External cavity lasers
- H01S5/141—External cavity lasers using a wavelength selective device, e.g. a grating or etalon
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- 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
- H01S5/40—Arrangement of two or more semiconductor lasers, not provided for in groups H01S5/02 - H01S5/30
- H01S5/4025—Array arrangements, e.g. constituted by discrete laser diodes or laser bar
- H01S5/4087—Array arrangements, e.g. constituted by discrete laser diodes or laser bar emitting more than one wavelength
Definitions
- the invention relates to a device for wavelength multiplexing of a plurality of laser sources and in particular of beams emitted by an array of laser diodes.
- the power delivered by a laser diode being limited (typically less than 10 W), it is conventional to use monolithic assemblies of diodes (called arrays of laser diodes) making it possible to deliver powers up to typically 100 W
- arrays have the following characteristics: disadvantage of delivering an optical beam of very poor quality, the elementary diodes emitting side by side Generally 1 cm wide in the direction parallel to the plane of the junction (D // ), the emissive surface of the bars is about 1 ⁇ m high in the perpendicular direction (Dj .
- a bar is thus a highly asymmetrical source, being approximately 10 000 times wider than high Similarly, the divergence of the radiation is non-symmetrical greater than 25 ° (30 ° to 50 °) according to D ⁇ , it is approximately 10 ° according to D // The combination of these two characteristics leads to a geometric extent approximately 2000 times greater according to D // than selo n D ⁇ This high asymmetry is completely detrimental to the effective use of these components for many applications. In fact, in addition to the difficulty of handling, it is generally advantageous to have a beam of geometric extent close to the symmetry of revolution, for example, for injection into an optical fiber or for the longitudinal optical pumping of solid lasers
- the invention therefore relates to a wavelength multiplexer of laser sources, characterized in that it comprises
- a plurality of laser sources emitting beams at different wavelengths A first diffraction grating forming a cavity mirror for the laser diodes, this grating comprising a set of juxtaposed sub-grids of different pitches, each sub-grating receiving one or more of said laser beams, retroreflecting part of the beam or beams and transmitting the other part of the beam in an exit direction, this direction being the same for all the sub-beams;
- a focusing optic located on the output direction, focusing at a focal point the beams emitted by the laser sources
- a second diffraction grating located at said focal point and receiving said emitted beams, the angles of incidence of these beams on the diffraction grating being such that the latter superimposes the beams after diffraction.
- FIGS. 1a to 1c an example of a detailed embodiment of the multiplexer of the invention
- Figures 2a and 2b an alternative embodiment of the invention
- Figures 1 a to 1 c show an embodiment of the multiplexer according to the invention.
- Figures 1a and 1b show a device for the emission of n laser beams of different wavelengths.
- Figure 1a shows n laser diodes 1.1 to 1.n.
- these n diodes are in fact a strip of laser diodes 1.
- the beams emitted by these diodes are collimated by a first cylindrical lens 21, then focused by a second cylindrical lens 22 on a diffraction grating 3 located substantially at the focusing plane. of the lens 22.
- the axes of the cylindrical lenses 21, 22 are orthogonal to the long length of the diode array and form an afocal system.
- the diffraction grating 3 is in reality a juxtaposition of diffraction sub-grids 3.1 to 3.n having different pitches so as to be effective at different wavelengths.
- the wavelength of each of the n laser diodes 1.1 to 1.n of the strip 1 is imposed by making an external cavity closed by a network 3 placed in the Littrow position, the plane of incidence of which is perpendicular to the plane. of the junction of the laser diodes.
- This orientation of the network is chosen to ensure good selection in wavelength, which would not necessarily be the case for an orientation parallel to the plane of the junction due to the non-monomode spatial emission in this direction of the power diodes. .
- Order 0 of the network corresponds to the output beams 4.1 to 4.n of the cavity and order -1 to the beam reinjected into the cavity.
- the angle of incidence of the beams on the grating and the pitch of the grating fix the value of the emission wavelength of each laser diode. It is necessary for the beam to be collimated in the plane of incidence of the grating, for example by putting a third cylindrical lens 23 between the strip 1 and the grating 3. This third cylindrical lens 23 is orthogonal to the lenses 21, 22. This is visible in Figure 1b which shows a bottom view of the system of Figure 1a.
- each laser diode should light only one sub-array. This is achieved by afocal mounting of the two cylindrical lenses 21 -22 which image the laser diodes on the array 3.
- the n beams coming from the diodes each have a different wavelength and are parallel between them. They are spaced by a distance dx which corresponds to the distance between diodes in the strip multiplied by the magnification of the lenses 21-22.
- a preferential example consists in having the beams 4.1 to 4.n parallel to each other and spatially distributed as a function of their wavelengths.
- the n beams 4.1 to 4.n are then superimposed locally by a lens 5 on a diffraction grating 6.
- the focal point of the lens 5 is placed on network 3.
- Network 6 is placed in the Fourrier plane (image focus).
- the lens 5 can be cylindrical or spherical.
- the network 6 is a network jaded to have a preferential direction at the output 7. For the beams 4n to be spatially superimposed after the network 6, their wavelength ⁇ n must be chosen judiciously.
- the beams of the N laser diodes making up a strip are therefore spatially superimposed.
- the wavelength spacing d ⁇ n between two elementary beams is independent of n (this is verified as long as the incidences on the lens 5 remain low).
- the invention proposes, for example, to use a photosensitive polymer to produce the gratings 3 in the form of a thick hologram, either by using a length d 'fixed writing wave and by varying the incidences of the beams according to the location on the network 3; either by varying the write wavelength for each sub-network.
- the second network 6 has a fixed number of lines, which corresponds to a dispersing power D (which also depends on the working angle chosen).
- D dispersing power
- the beams are separated at the level of the network 3. This is carried out over a distance of the order of a millimeter at the outlet of the bar (spacing of 0.2 mm, divergence of 10 °). We can thus remove the lenses 21 and 22 as we can see in Figures 2a and 2b.
- the beam can be used directly or focused in an optical fiber.
- Diffraction grids 3 and 6 can operate in transmission or in reflection.
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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 wavelength multiplexer comprising: a plurality of laser sources (S1 to Sn, 1.1 to 1.n) emitting beams at different wavelengths; a first diffraction grating (3) forming a cavity mirror for the laser diodes. Said grating comprises an assembly of juxtaposed sub-gratings with different pitches. Each sub-grating receives one or several laser beams, retroreflects part of the beam(s) and transmits the other part of the beam in an output direction (U), said direction being the same for all the sub-beams; a focusing optics which is located in the output direction (U) (lens 5), and which focuses into a focal point the beams emitted by the laser sources; a second diffraction grating (6) which is located at said focal point, receives said emitted beams. The angles of incidence of said beams on the diffraction grating are such that the latter superimposes the beams after diffraction.
Description
MULTIPLEXEUR EN LONGUEURS D'ONDES DE SOURCES LASERS WAVELENGTH MULTIPLEXER OF LASER SOURCES
L'invention concerne un dispositif de multiplexage en longueur d'onde d'une pluralité de sources lasers et notamment de faisceaux émis par une barrette de diodes lasersThe invention relates to a device for wavelength multiplexing of a plurality of laser sources and in particular of beams emitted by an array of laser diodes.
La puissance délivrée par une diode laser étant limitée (typiquement inférieure à 10 W), il est classique d'utiliser des assemblages monolithiques de diodes (appelés barrettes de diodes lasers) permettant de délivrer des puissances jusqu'à typiquement 100 W Ces barrettes présentent l'inconvénient de délivrer un faisceau optique de très mauvaise qualité, les diodes élémentaires émettant côte a côte Généralement de 1 cm de large dans la direction parallèle au plan de la jonction (D//), la surface emissive des barrettes est d'environ 1 μm de haut dans la direction perpendiculaire (Dj.) Une barrette est ainsi une source fortement dissymétrique, étant environ 10 000 fois plus large que haute De même, la divergence du rayonnement est non symétrique supérieure à 25° (30° à 50°) selon D±, elle est d'environ 10° suivant D// La combinaison de ces deux caractéristiques conduit à une étendue géométrique environ 2000 fois plus grande selon D// que selon D± Cette forte dissymétrie est tout à fait préjudiciable à l'emploi efficace de ces composants pour de nombreuses applications En effet, outre la difficulté de manipulation, il est en général intéressant de disposer d'un faisceau d'étendue géométrique proche de la symétrie de révolution, par exemple, pour l'injection dans une fibre optique ou pour le pompage optique longitudinal de lasers solidesThe power delivered by a laser diode being limited (typically less than 10 W), it is conventional to use monolithic assemblies of diodes (called arrays of laser diodes) making it possible to deliver powers up to typically 100 W These arrays have the following characteristics: disadvantage of delivering an optical beam of very poor quality, the elementary diodes emitting side by side Generally 1 cm wide in the direction parallel to the plane of the junction (D // ), the emissive surface of the bars is about 1 μm high in the perpendicular direction (Dj . ) A bar is thus a highly asymmetrical source, being approximately 10 000 times wider than high Similarly, the divergence of the radiation is non-symmetrical greater than 25 ° (30 ° to 50 °) according to D ± , it is approximately 10 ° according to D // The combination of these two characteristics leads to a geometric extent approximately 2000 times greater according to D // than selo n D ± This high asymmetry is completely detrimental to the effective use of these components for many applications. In fact, in addition to the difficulty of handling, it is generally advantageous to have a beam of geometric extent close to the symmetry of revolution, for example, for injection into an optical fiber or for the longitudinal optical pumping of solid lasers
Superposer différents faisceaux lasers est possible par multiplexage en longueur d'onde chaque laser émet à une longueur d'onde différente des autres et les faisceaux sont superposés à l'aide de miroirs dichroiques ou d'éléments dispersifs (réseaux, prismes) [C C Cook et T Y Fan, in Advanced Solid State Laser 99, OSA Technical Digest, paper PD7 , M C Famés et al , Electron Lett , vol 27, pp 1498-1499 (15 08 91 ) , I H White et al, Electron Lett , vol 26, pp 832-834 (21/6/90)] L'invention concerne donc un multiplexeur en longueurs d ondes de sources lasers, caractérisé en ce qu'il comporteSuperimposing different laser beams is possible by wavelength multiplexing, each laser emits at a different wavelength from the others and the beams are superimposed using dichroic mirrors or dispersive elements (networks, prisms) [CC Cook and TY Fan, in Advanced Solid State Laser 99, OSA Technical Digest, paper PD7, MC Famés et al, Electron Lett, vol 27, pp 1498-1499 (15 08 91), IH White et al, Electron Lett, vol 26, pp 832-834 (21/6/90)] The invention therefore relates to a wavelength multiplexer of laser sources, characterized in that it comprises
• une pluralité de sources lasers émettant des faisceaux à des longueurs d'ondes différentes ,
• un premier réseau de diffraction formant miroir de cavité pour les diodes lasers, ce réseau comportant un ensemble de sous- réseaux juxtaposés de pas différents, chaque sous-réseau recevant un ou plusieurs desdits faisceaux lasers, rétroréfléchissant une partie du ou des faisceaux et transmettant l'autre partie du faisceau dans une direction de sortie, cette direction étant la même pour tous les sous- faisceaux ;A plurality of laser sources emitting beams at different wavelengths, A first diffraction grating forming a cavity mirror for the laser diodes, this grating comprising a set of juxtaposed sub-grids of different pitches, each sub-grating receiving one or more of said laser beams, retroreflecting part of the beam or beams and transmitting the other part of the beam in an exit direction, this direction being the same for all the sub-beams;
• une optique de focalisation située sur la direction de sortie, focalisant en un point de focalisation les faisceaux émis par les sources lasers ;• a focusing optic located on the output direction, focusing at a focal point the beams emitted by the laser sources;
• un deuxième réseau de diffraction situé audit point de focalisation et recevant lesdits faisceaux émis, les angles d'incidence de ces faisceaux sur le réseau de diffraction étant tels que celui-ci superpose les faisceaux après diffraction.• a second diffraction grating located at said focal point and receiving said emitted beams, the angles of incidence of these beams on the diffraction grating being such that the latter superimposes the beams after diffraction.
Les différents objets et caractéristiques de l'invention apparaîtront plus clairement dans la description qui va suivre faite à titre d'exemple de réalisation ainsi que dans les figures annexées qui représentent : les figures 1a à 1c, un exemple de réalisation détaillé du multiplexeur de l'invention ; les figures 2a et 2b, une variante de réalisation de l'invention. Les figures 1 a à 1 c représentent un exemple de réalisation du multiplexeur selon l'invention.The various objects and characteristics of the invention will appear more clearly in the description which follows, given by way of example of embodiment, as well as in the appended figures which represent: FIGS. 1a to 1c, an example of a detailed embodiment of the multiplexer of the invention; Figures 2a and 2b, an alternative embodiment of the invention. Figures 1 a to 1 c show an embodiment of the multiplexer according to the invention.
Les figures 1 a et 1 b représentent un dispositif permettant l'émission de n faisceaux lasers de longueurs d'ondes différentes.Figures 1a and 1b show a device for the emission of n laser beams of different wavelengths.
La figure 1 a représente n diodes lasers 1.1 à 1.n. Préférentiellement, ces n diodes sont en fait une barrette de diodes lasers 1. Les faisceaux émis par ces diodes sont collimatés par une première lentille cylindrique 21 , puis focalisés par une deuxième lentille cylindrique 22 sur un réseau de diffraction 3 situé sensiblement au plan de focalisation de la lentille 22. Les axes des lentilles cylindriques 21 , 22 sont orthogonaux à la grande longueur de la barrette de diodes et forment un système afocal.Figure 1a shows n laser diodes 1.1 to 1.n. Preferably, these n diodes are in fact a strip of laser diodes 1. The beams emitted by these diodes are collimated by a first cylindrical lens 21, then focused by a second cylindrical lens 22 on a diffraction grating 3 located substantially at the focusing plane. of the lens 22. The axes of the cylindrical lenses 21, 22 are orthogonal to the long length of the diode array and form an afocal system.
Le réseau de diffraction 3 est en réalité une juxtaposition de sous- réseaux de diffraction 3.1 à 3.n présentant des pas différents de façon à être efficaces à des longueurs d'ondes différentes.
On impose la longueur d'onde de chacune des n diodes lasers 1.1 à 1.n de la barrette 1 par la réalisation d'une cavité externe fermée par un réseau 3 placé en position de Littrow dont le plan d'incidence est perpendiculaire au plan de la jonction des diodes lasers. Cette orientation du réseau est choisie pour assurer une bonne sélection en longueur d'onde, ce qui ne serait pas forcément le cas pour une orientation parallèle au plan de la jonction à cause de l'émission non monomode spatiale dans cette direction des diodes de puissance. L'ordre 0 du réseau correspond aux faisceaux de sortie 4.1 à 4.n de la cavité et l'ordre -1 au faisceau réinjecté dans la cavité. Pour éviter le phénomène de sous-cavité qui pourrait compromettre l'efficacité de la sélection en longueur d'onde, il est préférable de traiter antireflet la face de sortie des diodes lasers. L'angle d'incidence des faisceaux sur le réseau et le pas du réseau fixent la valeur de la longueur d'onde d'émission de chaque diode laser. Il est nécessaire que le faisceau soit collimate dans le plan d'incidence du réseau par exemple en mettant une troisième lentille cylindrique 23 entre la barrette 1 et le réseau 3. Cette troisième lentille cylindrique 23 est orthogonale aux lentilles 21 , 22. Cela est visible sur la figure 1b qui représente une vue de dessous du système de la figure 1a. Enfin, chaque diode laser ne doit éclairer qu'un seul sous-réseau. Cela est réalisé par le montage afocal des deux lentilles cylindriques 21 -22 qui imagent les diodes laser sur le réseau 3. Ainsi, en sortie du réseau 3, les n faisceaux issus des diodes ont chacun une longueur d'onde différente et sont parallèles entre eux. Ils sont espacés d'une distance dx qui correspond à la distance entre diodes dans la barrette multipliée par le grandissement des lentilles 21-22.The diffraction grating 3 is in reality a juxtaposition of diffraction sub-grids 3.1 to 3.n having different pitches so as to be effective at different wavelengths. The wavelength of each of the n laser diodes 1.1 to 1.n of the strip 1 is imposed by making an external cavity closed by a network 3 placed in the Littrow position, the plane of incidence of which is perpendicular to the plane. of the junction of the laser diodes. This orientation of the network is chosen to ensure good selection in wavelength, which would not necessarily be the case for an orientation parallel to the plane of the junction due to the non-monomode spatial emission in this direction of the power diodes. . Order 0 of the network corresponds to the output beams 4.1 to 4.n of the cavity and order -1 to the beam reinjected into the cavity. To avoid the phenomenon of sub-cavity which could compromise the efficiency of the wavelength selection, it is preferable to anti-reflective treat the output face of the laser diodes. The angle of incidence of the beams on the grating and the pitch of the grating fix the value of the emission wavelength of each laser diode. It is necessary for the beam to be collimated in the plane of incidence of the grating, for example by putting a third cylindrical lens 23 between the strip 1 and the grating 3. This third cylindrical lens 23 is orthogonal to the lenses 21, 22. This is visible in Figure 1b which shows a bottom view of the system of Figure 1a. Finally, each laser diode should light only one sub-array. This is achieved by afocal mounting of the two cylindrical lenses 21 -22 which image the laser diodes on the array 3. Thus, at the output of the array 3, the n beams coming from the diodes each have a different wavelength and are parallel between them. They are spaced by a distance dx which corresponds to the distance between diodes in the strip multiplied by the magnification of the lenses 21-22.
Un exemple préférentiel consiste à avoir les faisceaux 4.1 à 4.n parallèles entre eux et répartis spatialement en fonction de leurs longueurs d'ondes. La distance dx entre deux faisceaux, 4.1 et 4.2 par exemple, est telle que : dx = f.dλ.DA preferential example consists in having the beams 4.1 to 4.n parallel to each other and spatially distributed as a function of their wavelengths. The distance dx between two beams, 4.1 and 4.2 for example, is such that: dx = f.dλ.D
• f étant la distance focale de la lentille 5 ;• f being the focal distance of the lens 5;
• dλ, la différence de longueurs d'ondes des faisceaux 4.1 et 4.2 ;• dλ, the difference in wavelengths of beams 4.1 and 4.2;
• D, le pouvoir de diffraction du réseau de diffraction 6.• D, the diffraction power of the diffraction grating 6.
Les n faisceaux 4.1 à 4.n sont alors superposés localement par une lentille 5 sur un réseau de diffraction 6. Le foyer objet de la lentille 5 est
placé sur le réseau 3. Le réseau 6 est placé dans le plan de Fourrier (foyer image). La lentille 5 peut être cylindrique ou sphérique. Le réseau 6 est un réseau blasé pour avoir une direction préférentielle en sortie 7. Pour que les faisceaux 4n soient spatialement superposés après le réseau 6, il faut que leur longueur d'onde λn soit choisie judicieusement.The n beams 4.1 to 4.n are then superimposed locally by a lens 5 on a diffraction grating 6. The focal point of the lens 5 is placed on network 3. Network 6 is placed in the Fourrier plane (image focus). The lens 5 can be cylindrical or spherical. The network 6 is a network jaded to have a preferential direction at the output 7. For the beams 4n to be spatially superimposed after the network 6, their wavelength λ n must be chosen judiciously.
On a donc par ce procédé, superposé spatialement les faisceaux des N diodes laser composant une barrette.By this method, the beams of the N laser diodes making up a strip are therefore spatially superimposed.
En première approximation, l'espacement en longueur d'onde dλn entre deux faisceaux élémentaires est indépendant de n (cela est vérifié tant que les incidences sur la lentille 5 restent faibles). On a donc : dλn = λn - λn-ι = dλ qui est constant. Cette valeur est choisie pour être supérieure à la largeur spectrale des diodes lasers fonctionnant en cavité externe. Typiquement, on prendra dλ = 0,5 à 1 nm. Dans ces conditions, pour le réseau 3, la variation (da) du pas (a) d'un sous-réseau au sous-réseau adjacent est donné par :As a first approximation, the wavelength spacing dλ n between two elementary beams is independent of n (this is verified as long as the incidences on the lens 5 remain low). We therefore have: dλ n = λ n - λ n -ι = dλ which is constant. This value is chosen to be greater than the spectral width of the laser diodes operating in an external cavity. Typically, we will take dλ = 0.5 at 1 nm. Under these conditions, for network 3, the variation (da) of the step (a) of a sub-network to the adjacent sub-network is given by:
da _ dλ a " λda _ dλ a " λ
Par exemple avec λ = 800 nm, dλ = 1 nm et a = 0,8 μm (réseau avec 1/1200 traits/mm) on obtient da = 1 nm. Pour réaliser n réseaux dont le pas varie de proche en proche de 0,5 nm, l'invention propose, par exemple, d'utiliser un polymère photosensible pour réaliser le réseau 3 sous forme d'hologramme épais, soit en utilisant une longueur d'onde d'écriture fixe et en faisant varier les incidences des faisceaux suivant l'emplacement sur le réseau 3 ; soit en faisant varier la longueur d'onde d'écriture pour chaque sous-réseau.For example with λ = 800 nm, dλ = 1 nm and a = 0.8 μm (network with 1/1200 lines / mm) we obtain da = 1 nm. To produce n gratings whose pitch varies from close to close to 0.5 nm, the invention proposes, for example, to use a photosensitive polymer to produce the gratings 3 in the form of a thick hologram, either by using a length d 'fixed writing wave and by varying the incidences of the beams according to the location on the network 3; either by varying the write wavelength for each sub-network.
Le deuxième réseau 6 a un nombre de traits fixé, ce qui correspond à un pouvoir de dispersion D (qui dépend également de l'angle de travail choisi). Dans le cas du montage optique présenté figure 1 c, on obtient aisément la relation entre l'espacement spatial dx et spectral dλ entre sous-faisceaux : dx = f.dλ.D où f est la longueur focale de la lentille 5. Par exemple, avec dx = 0,2 mm, dλ = 1 nm et D = 1200 mm'Vcos 45°, on obtient f = 120 mm.
Sans sortir du cadre de l'invention, on prévoit également, par exemple que :The second network 6 has a fixed number of lines, which corresponds to a dispersing power D (which also depends on the working angle chosen). In the case of the optical assembly presented in FIG. 1 c, the relationship between the spatial spacing dx and spectral dλ between sub-beams is easily obtained: dx = f.dλ.D where f is the focal length of the lens 5. For example , with dx = 0.2 mm, dλ = 1 nm and D = 1200 mm ' Vcos 45 °, we obtain f = 120 mm. Without departing from the scope of the invention, it is also provided, for example, that:
• D'autres combinaisons de lentilles et d'autres incidences sur les réseaux soient utilisées. • L'imagerie dans le plan de la jonction des diodes sur le réseau• Other combinations of lenses and other network effects are used. • In-plane imaging of the diode junction on the network
3 ne soit pas obligatoire, il suffit que les faisceaux soient séparés au niveau du réseau 3. Cela est réalisé sur une distance de l'ordre du millimètre en sortie de la barrette (espacement de 0,2 mm, divergence de 10°). On peut ainsi supprimer les lentilles 21 et 22 comme on peut le voir sur les figures 2a et 2b.3 is not compulsory, it is sufficient that the beams are separated at the level of the network 3. This is carried out over a distance of the order of a millimeter at the outlet of the bar (spacing of 0.2 mm, divergence of 10 °). We can thus remove the lenses 21 and 22 as we can see in Figures 2a and 2b.
• En sortie du réseau 6, le faisceau peut être utilisé directement ou focalisé dans une fibre optique.• At the output of network 6, the beam can be used directly or focused in an optical fiber.
• On peut profiter de la cavité externe pour non seulement fixer la longueur d'onde de chaque diode laser mais également opérer un filtrage spatial du mode latéral pour réduire le nombre de modes transverses émis par chaque diode laser.• We can take advantage of the external cavity to not only fix the wavelength of each laser diode but also operate a spatial filtering of the lateral mode to reduce the number of transverse modes emitted by each laser diode.
• Les réseaux de diffraction 3 et 6 peuvent fonctionner en transmission ou en réflexion.
• Diffraction grids 3 and 6 can operate in transmission or in reflection.
Claims
1. Multiplexeur en longueurs d'ondes de sources lasers, caractérisé en ce qu'il comporte :1. Multiplexer in wavelengths of laser sources, characterized in that it comprises:
• une pluralité de sources lasers (S1 à Sn, 1.1 à 1.n) émettant des faisceaux à des longueurs d'ondes différentes ; • un premier réseau de diffraction (3) formant miroir de cavité pour les diodes lasers, ce réseau comportant un ensemble de sous-réseaux juxtaposés de pas différents, chaque sous- réseau recevant un ou plusieurs desdits faisceaux lasers, rétroréfléchissaπt une partie du ou des faisceaux et transmettant l'autre partie du faisceau dans une direction de sortie (U), cette direction étant la même pour tous les sous- faisceaux ;• a plurality of laser sources (S1 to Sn, 1.1 to 1.n) emitting beams at different wavelengths; • a first diffraction grating (3) forming a cavity mirror for the laser diodes, this grating comprising a set of juxtaposed sub-grids of different pitches, each sub-grating receiving one or more of said laser beams, retroreflecting part of the beams and transmitting the other part of the beam in an exit direction (U), this direction being the same for all the sub-beams;
• une optique de focalisation située sur la direction de sortie (U) (lentille 5), focalisant en un point de focalisation les faisceaux émis par les sources lasers ;• a focusing optic located on the output direction (U) (lens 5), focusing at a focal point the beams emitted by the laser sources;
• un deuxième réseau de diffraction (6) situé audit point de focalisation et recevant lesdits faisceaux émis, les angles d'incidence de ces faisceaux sur le réseau de diffraction étant tels que celui-ci superpose les faisceaux après diffraction. • a second diffraction grating (6) located at said focal point and receiving said emitted beams, the angles of incidence of these beams on the diffraction grating being such that the latter superimposes the beams after diffraction.
2. Multiplexeur selon la revendication 1 , caractérisé en ce qu'avant focalisation par l'optique de focalisation (5), les faisceaux sont parallèles et les distances entre les axes des faisceaux sont calculées et réparties pour obtenir la superposition des faisceaux après diffraction par le réseau de diffraction. 2. Multiplexer according to claim 1, characterized in that before focusing by the focusing optics (5), the beams are parallel and the distances between the axes of the beams are calculated and distributed to obtain the superposition of the beams after diffraction by the diffraction grating.
3. Mutliplexeur selon la revendication 2, caractérisé en ce que la distance dx entre deux faisceaux est donnée par la formule : dx = f.dλ.D dans laquelle :3. A multiplexer according to claim 2, characterized in that the distance dx between two beams is given by the formula: dx = f.dλ.D in which:
• f étant la distance focale de l'optique de focalisation (5) ; • dλ, la différence de longueurs d'ondes des faisceaux ;• f being the focal length of the focusing optics (5); • dλ, the difference in wavelengths of the beams;
• D est le pouvoir de dispersion du deuxième réseau de diffraction (6). • D is the dispersing power of the second diffraction grating (6).
4. Multiplexeur selon la revendication 1 , caractérisé en ce que les deux réseaux de diffraction (3, 6) fonctionnent en réflexion ou en transmission.4. Multiplexer according to claim 1, characterized in that the two diffraction gratings (3, 6) operate in reflection or in transmission.
5. Multiplexeur selon la revendication 2, caractérisé en ce qu'il comporte, entre les diodes lasers et le premier réseau de diffraction (3), une première lentille cylindrique (21 ) collimatant les faisceaux lasers et une deuxième lentille cylindrique (22) située entre la première lentille cylindrique et le premier réseau de diffraction, et focalisant les faisceaux collimatés sur le plan du premier réseau de diffraction et imageant les faces émissives des diodes lasers sur ce premier réseau, les axes des lentilles cylindriques (21 , 22) étant orthogonaux à la ligne de diodes lasers.5. Multiplexer according to claim 2, characterized in that it comprises, between the laser diodes and the first diffraction grating (3), a first cylindrical lens (21) collimating the laser beams and a second cylindrical lens (22) located between the first cylindrical lens and the first diffraction grating, and focusing the collimated beams on the plane of the first diffraction grating and imaging the emissive faces of the laser diodes on this first grating, the axes of the cylindrical lenses (21, 22) being orthogonal to the line of laser diodes.
6. Multiplexeur selon la revendication 5, caractérisé en ce qu'il comporte une troisième lentille cylindrique (23), orthogonale à la première et à la deuxième lentilles, située entre les diodes lasers et le deuxième réseau de diffraction (3) et collimatant les faisceaux émis par les diodes lasers. 6. Multiplexer according to claim 5, characterized in that it comprises a third cylindrical lens (23), orthogonal to the first and to the second lenses, located between the laser diodes and the second diffraction grating (3) and collimating the beams emitted by laser diodes.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9916401A FR2803116B1 (en) | 1999-12-23 | 1999-12-23 | WAVELENGTH MULTIPLEXER OF LASER SOURCES |
FR9916401 | 1999-12-23 | ||
PCT/FR2000/003644 WO2001048882A1 (en) | 1999-12-23 | 2000-12-21 | Laser source wavelength multiplexer |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1155484A1 true EP1155484A1 (en) | 2001-11-21 |
Family
ID=9553768
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00993665A Withdrawn EP1155484A1 (en) | 1999-12-23 | 2000-12-21 | Laser source wavelength multiplexer |
Country Status (4)
Country | Link |
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EP (1) | EP1155484A1 (en) |
AU (1) | AU2857001A (en) |
FR (1) | FR2803116B1 (en) |
WO (1) | WO2001048882A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2006025849A2 (en) | 2004-01-20 | 2006-03-09 | Trumpf Photonics, Inc. | High-power semiconductor laser |
DE102004053137A1 (en) * | 2004-10-29 | 2006-05-11 | Raab, Volker, Dr. | Multispectral laser with multiple gain elements |
FR2883384B1 (en) * | 2005-03-18 | 2008-01-18 | Thales Sa | OPTICAL DEVICE FOR WAVELENGTH MULTIPLEXING |
US7627013B2 (en) * | 2006-02-03 | 2009-12-01 | Hewlett-Packard Development Company, L.P. | Light source module |
US9690107B2 (en) * | 2013-03-15 | 2017-06-27 | Trumpf Laser Gmbh | Device for wavelength combining of laser beams |
JPWO2023021675A1 (en) * | 2021-08-20 | 2023-02-23 |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS574007A (en) * | 1980-06-07 | 1982-01-09 | Takumi Tomijima | Multiple wavelength light communication system |
JPS61251183A (en) * | 1985-04-30 | 1986-11-08 | Fujitsu Ltd | Two frequency semiconductor laser |
US5351262A (en) * | 1992-09-10 | 1994-09-27 | Bell Communications Research, Inc. | Multi-stripe array grating integrated cavity laser |
-
1999
- 1999-12-23 FR FR9916401A patent/FR2803116B1/en not_active Expired - Fee Related
-
2000
- 2000-12-21 EP EP00993665A patent/EP1155484A1/en not_active Withdrawn
- 2000-12-21 AU AU28570/01A patent/AU2857001A/en not_active Abandoned
- 2000-12-21 WO PCT/FR2000/003644 patent/WO2001048882A1/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
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See references of WO0148882A1 * |
Also Published As
Publication number | Publication date |
---|---|
FR2803116A1 (en) | 2001-06-29 |
WO2001048882A1 (en) | 2001-07-05 |
AU2857001A (en) | 2001-07-09 |
FR2803116B1 (en) | 2002-03-22 |
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