Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
  • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
  • G02B6/122—Basic optical elements, e.g. light-guiding paths
  • G02B6/1228—Tapered waveguides, e.g. integrated spot-size transformers
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/24—Coupling light guides
  • G02B6/42—Coupling light guides with opto-electronic elements
  • G02B6/4201—Packages, e.g. shape, construction, internal or external details
  • G02B6/4249—Packages, e.g. shape, construction, internal or external details comprising arrays of active devices and fibres
• • 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
  • H01S2301/18—Semiconductor lasers with special structural design for influencing the near- or far-field
• • 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

Definitions

• the present invention relates to a guiding structure for transforming a profile propagation mode of the Gaussian type into a profile propagation mode of the extended type.
• This invention can be used with many components of optics and in particular of integrated optics and in particular with spark gaps (called in English terminology “pitch converters” or “spacing converters”), multiplexers ⁇ demultiplexers of wavelengths.
• a light wave propagates either in a planar guide, or in a laterally confined optical guide which will be called microguide.
• a planar guide or microguide consists of a central part called the heart and surrounding environments located all around and which may be identical to each other or different.
• the refractive index of the medium composing this part must be different and generally superior to those of the surrounding mediums.
• planar guide and the microguide will be assimilated to their central parts. Furthermore, all or part of the surrounding media will be called, substrate being understood that when the microguide or the planar guide is not or only slightly buried, one of the surrounding media may for example be air.
• the substrate may be monolayer or multilayer.
• a wave propagation mode corresponds to an area of space or a structure where the energy of the light wave is confined.
• Gaussian profiles are defined with respect to a plane along the xy axes, perpendicular to the direction of propagation z, the x axis being an axis parallel to the plane of the guide substrate.
• FIG. Ia there is shown by way of example, a propagation profile P Q of the Gaussian type of an incident light wave for a wavelength ⁇ i, called the central wavelength, and a propagation profile P g Gaussian type of a microguide, for this wavelength ⁇ i.
• These profiles illustrate the intensity distribution I according to the x axis (the same types of profiles and reasoning can be performed along the y axis).
• the light intensity coming from the incident wave and coupled in the guide depends on the integral of overlap between these two profiles; this covering integral corresponds in FIG. 1a to the hatched area.
• the light intensity coupled in the guide is shown as a function of ⁇ x .
• the profile Pi obtained is of the Gaussian type with an average width L ix (defined for example at 80% of the value Ii).
• the same reasoning may be held along the y axis.
• the variation ⁇ x and / or ⁇ y may be due to many factors such as for example thermal disturbances, positioning errors in x and / or y of the incident wave at the input of the guide, etc. more particular, variations in external parameters such as temperature, produce in particular in demultiplexing devices, variations in the central wavelength ⁇ i of a value ⁇ which also results in a variation of ⁇ x proportional in general to ⁇ ⁇ . This variation can be particularly detrimental in optical devices.
• the invention proposes an original guiding structure allowing to have the most stable possible integral of recovery despite possible variations of variations x and / or ⁇ y / so that the coupling between the wave incident and the guiding structure is as less sensitive as possible to the variations of ⁇ x and / or ⁇ y and therefore also of ⁇ .
• An object of the invention is therefore to have a guiding structure having at least one guided mode as insensitive as possible to the variations of ⁇ x and / or ⁇ y and making it possible to obtain the largest possible recovery integral to have a maximum coupling coefficient on a translation plane Pxy along the x and / or y axes.
• said guided mode must have the widest possible profile on this translation plane.
• the guiding structure of the invention must therefore make it possible to transform a profile propagation mode of the Gaussian type into a profile propagation mode of the enlarged type in order to have a covering integral that is as insensitive as possible to any variations in ⁇ x and / or ⁇ y in the translation plane and as large as possible in particular to minimize injection losses.
• the guiding structure of the invention is particularly advantageous in wavelength multiplexing / demultiplexing devices.
• the invention provides a guiding structure making it possible to transform a light wave having at least one central wavelength ⁇ i of profile propagation mode of Gaussian type, originating from introduction means, into a propagation mode of enlarged type profile, this structure comprising:
• a second part in integrated optics comprising at least one microguide, one end of which has a Y shape at least in a plane parallel to a direction z of propagation of the wave, the first and the second part as well as the means of introduction are optically linked together so that when the light wave is introduced into one of the first or second parts, it is transformed in the other of the parts into an enlarged profile for the central wavelength ⁇ i.
• the guiding structure comprises a dispersive element optically connecting the first and the second part.
• dispersive element is meant any element capable of spatially separating wavelengths of the light wave.
• the means for introducing the light wave are arranged at least at one of the ends of the first part, the other end of said first part is optically connected to the Y end of the second part, said enlarged profile then being obtained in the microguide of the second part.
• microguides in integrated optics makes it possible to have a miniaturized structure compared to conventional techniques using optical fibers in "V" blocks which are limited by the diameter of their sheath (generally 125 ⁇ m).
• the fact of carrying out the second part in integrated optics makes it possible to modify the parameters of the microguides with respect to one another, in particular to modify the adjacent coupling between the microguides, which reduces parasitic interference between microguides.
• the means for introducing the light wave are arranged at least at one of the ends of the second part, the other end corresponding to the Y end is optically connected to one of the ends of the first part, said enlarged profile then being obtained in the first part.
• the first part applicable to the first variant it is made in free space.
• the first part comprises a planar guide.
• this comprises at least one optical fiber or an optical microguide, one of the ends of which is connected either directly or via an intermediate optical element and / or via a free space, at the Y end of a microguide of the second part.
• the end of the microguide optically connected to the second part can also have a Y shape or a funnel shape.
• the first guiding part can also be produced by a combination of these modes.
• the first guiding part is advantageously a single guiding structure, which makes it possible to minimize the optical losses.
• the Y-shaped end of the microguide of the second part or of the first part comprises two guiding parts joining in a single guiding part.
• the Y shape is advantageously defined at least in an xz plane parallel to the direction of propagation of the light wave in order to minimize the sensitivity to possible variations of ⁇ x and therefore of ⁇ .
• the Y shape can also be defined in the yz plane perpendicular to the xz plane to possibly reduce the sensitivity to variations in ⁇ y.
• the guiding structure further comprises a dispersive element chosen from reflection means such as for example a diffraction grating or a holographic grating or transmission means such as for example a holographic grating or an acoustical element. optical, this dispersive element being able to optically connect the first and second parts.
• the means for introducing the light wave comprise at least one light source optically connected to one of the parts.
• the light wave coming from the introduction means and introduced into one of the first or second parts has a single central wavelength ⁇ i or several central wavelengths ⁇ i, ⁇ , ... i, ... ⁇ n .
• the light wave introduced into one of the parts has several central wavelengths ⁇ i # ⁇ 2 , ... ⁇ i, ...
• each microguide Gi is capable of guiding a central wavelength ⁇ i
• the first and the second parts are advantageously optically connected by the dispersive element so that a single central wavelength ⁇ is focused at the input of each microguide G x .
• the light wave introduced into one of the parts is formed of several light waves of different central wavelengths ⁇ x (for example from n sub-sources and the other part comprises a microguide capable of guiding all of the central wavelengths ⁇ 17 the first and the second parts are advantageously connected optically by the dispersing element so that the different wavelengths central ⁇ ⁇ are focused at the entrance to the microguide of said other part.
• the dispersive element makes it possible to reflect or transmit the light wave with angles substantially proportional to the wavelengths that we want to introduce respectively into the microguides of said other part.
• each central wavelength is reflected or transmitted with a particular angle making it possible to distribute the different central wavelengths respectively on a microguide of the other party.
• the dispersive element therefore also makes it possible to select wavelengths by sending them to different points in the space of a focal plane.
• Reflection means can also be used at the output of the guiding structure to transmit the output light wave to one or more means, for example a detector and / or a component. It is also possible, as a variant, to use output couplers. of the guiding structure.
• the outlet of the guiding structure corresponds to one end of the second part in the case of the first variant and to one end of the first part in the case of the second variant.
• the second part and possibly the first part are produced by the technique of ion exchange in glass.
• FIGS. 1a and 1b already described represent on the one hand the Gaussian profile of a light wave and the Gaussian profile of a guided mode and on the other hand the intensity coupled, resulting from these two profiles
• Figures 2a and 2b represent on the one hand the Gaussian profile of a light wave and the enlarged profile of a guided mode according to the invention and on the other hand the coupled intensity, resulting from these two profiles
• FIG. 3 schematically represents a top view, a first example of a guiding structure according to the invention
• FIG. 4 schematically represents a top view, a second example of a guiding structure according to the invention.
• FIG. 5 shows schematically in top view, a third example of a guiding structure according to the invention
• - Figure 6 shows schematically in top view, a guiding structure according to the invention, using a reflective element of the reflective type
• FIG. 7 schematically represents in top view, an example of application of the guiding structure of the invention to the production of a multiplexer
• FIG. 8 schematically represents a top view, an example of application of the guiding structure of the invention to the production of a demultiplexer
• FIG. 9 shows schematically in top view an example of a symmetrical variant of the preceding guiding structures
• FIG. 10 shows schematically in top view a guiding structure according to the invention using a dispersive element of the transmissive type.
• FIG. 2a represents the Gaussian profile P 0 of a light wave at the central wavelength ⁇ i and the enlarged profile P e of a guided mode obtained for this wavelength ⁇ i by the use of a Y in a guiding structure according to the invention.
• These profiles represent the intensity I as a function of x.
• the profile P e has two maximums because of the Y-shaped end used.
• the values x el and x e2 are of course linked to the dimensions of the Y.
• FIG. 2b illustrates the resulting light intensity, after passage of the wave of profile P 0 , in the guided mode of profile P e as a function of ⁇ x .
• Gaussian P 0 has been transformed into an enlarged profile P 2 of average width L 2x (defined for example at 80% of the value I 2 ), L 2x being much greater than L lx in Figure lb.
• FIG. 3 schematically illustrates in top view, a first example of a guiding structure according to the invention, associated with a light source S capable of emitting a light wave having at least one Gaussian profile for a central wavelength ⁇ i.
• This guiding structure comprises, opposite this source S, a first part 1, formed in this example by a free space which is able to allow the propagation of the light wave at least for the central wavelength ⁇ i; according to a Gaussian type propagation profile.
• This structure further comprises a second part 2, comprising at least one microguide 3 advantageously single-mode, one end 5 of which has a Y shape opposite the first part; this microguide is able to receive the wave of gaussian profile at the central wavelength ⁇ i coming from the first part and to transform it into a wave of widened propagation profile (see figure 2b) of central wavelength ⁇ i.
• connection means to another component and / or to processing means such as for example a detector.
• connection means there may be mentioned: an optical fiber 9 connected to the outlet 7 of the microguide 3 by an appropriate ferrule 11, or a free space with possibly reflective means or else adhesive suitable for maintain a component which may include for example a coupler.
• the Y-shaped end 5 of the microguide is made up of two separate guiding parts 5a and 5b, the optical axes of which are separated by a maximum distance d, meeting in a single guiding part.
• the microguide 3 has a mode diameter of 10.2 ⁇ m, a value d ranging from 2 to 20 ⁇ m, one end Y of length L along the z axis ranging from 100 to 5000 ⁇ m and an angle a ranging from 0.01 ° to 1 °, this angle a corresponding to the inclination of the branches of the Y relative to the z axis.
• Figure 4 there is shown schematically in top view a second example of a guiding structure according to the invention.
• the first part of the structure is a planar guide 15 disposed between the source S and the second part of the structure.
• This planar guide is able to allow the propagation of the light wave according to a plane xz parallel to that of the figure and containing the direction of propagation of the wave.
• This first part is attached to the second part, for example by gluing or made from the same substrate as the second part.
• the second part 2 is of the same type as that of FIG. 3.
• this source shows the source S optically connected directly to the first part of the structure, for example by gluing (it could also be connected indirectly, for example by a ferrule).
• FIG. 5 schematically represents a top view of a third example of a guiding structure of the invention.
• the first part of the structure is an optical fiber 17 (instead of a fiber, one could also have used an optical microguide produced in a substrate interposed between the source and the part 2).
• This fiber makes it possible to optically connect the source to the second part of the guiding structure; in this example, the fiber is mechanically connected respectively to the source by a ferrule 21 and to the second part of the guiding structure by another ferrule 23.
• This fiber is able to allow the propagation of the light wave according to a Gaussian type profile.
• the Y-shaped end 5d of the microguide 3 advantageously single-mode, has branches (at least in the plane xz parallel to that of the figure and containing the direction of propagation) more rounded than those of Figures 3 and 4.
• branches at least in the plane xz parallel to that of the figure and containing the direction of propagation
• the structure of the invention can also be achieved by a combination of these variants.
• the structure of the invention comprises, as we have seen, means for introducing the wave.
• these means are formed by a light source S optically connected to the first part or the second part, possibly via a free space.
• FIG 6 there is shown schematically in top view a guiding structure using a dispersive element such as reflection means.
• the first part comprises a microguide 33, one end of which faces a light source and the other end is located in view of the reflection means 31.
• the second part comprises at least one microguide 3, the Y-shaped end of which is opposite the reflection means while the other end forms the outlet of the guiding structure.
• the reflection means 31 are capable of reflecting the light wave coming from the microguide 33 of the first part 1, with an angle proportional to the wavelength that it is desired to introduce into the microguide 3 or the microguides 3 (s' there are several) of the second part.
• reflection means are produced for example by a diffraction grating or a holographic grating.
• the use of reflection means makes it possible in particular to have a more compact guiding structure, since the source is no longer necessarily placed facing the first or the second part of the guiding structure (unlike the previous figures).
• the source is arranged relative to the guiding structure, on the same side as the outlet of said structure.
• the reflection means make it possible to reflect the light wave coming from the microguide 33 with a particular angle for each of the wavelengths making it possible to distribute the central wavelength ⁇ x on a microguide Gi of the second part and the central wavelength ⁇ 2 on a microguide G 2 of the second part, distinct from Gi.
• the reflection means therefore also make it possible to select wavelengths by sending them to different points in the space of a focal plane located at the inputs of the second part. These reflection means thus make it possible to produce a wavelength demultiplexer.
• Reflection means can of course also be used at the output of the second part to transmit the output light wave to other means, for example a detector and / or another component.
• Reflection means can of course also be used at the output of the second part to transmit the output light wave to other means, for example a detector and / or another component.
• a source S of the same type as that shown in Figure 7 it would suffice to have a source S of the same type as that shown in Figure 7 at the inputs of the microguides 3 not having a Y shape and to recover at the output of the microguide 33 a wave having all the wavelengths ⁇ x up to ⁇ n .
• FIG. 7 schematically represents still in top view, another example of application of the structure of the invention to the production of a multiplexer.
• the light source is equivalent to a set of light sources S x , S 2 ,. Si..S n respectively emitting the central wavelengths ⁇ i, ⁇ 2 , ... ⁇ i, ... ⁇ n which are focused via the first part formed here by a free space, at the input of one end 5 of a microguide 3 of the second part.
• This microguide 3 is such that the propagation profiles of the Gaussian type and of central wavelengths ⁇ i entering the Y end of the microguide 3 emerge from the latter according to a single wave having wider v profiles for these lengths d wave.
• FIG. 8 schematically represents still in top view, another example of application of the structure of the invention to the production of a demultiplexer.
• the light source S emits via the first part, formed here by a free space, a wave having the central wavelengths ⁇ 1 # ⁇ 2 , ... ⁇ , ... ⁇ n in the direction of the ends 5 of n microguides 3 of the second part referenced Gi, .. - Gi, ... Gn.
• These microguides are arranged in the second part of the structure so that a single central wavelength ⁇ i is focused at the entry of a single microguide G.
• each wavelength ⁇ i entering a microguide Gi following a propagation profile of the Gaussian type is transformed in the second part following a more extended propagation profile.
• the light wave enters the first part and leaves the guiding structure through the second part.
• FIG. 9 schematically represents in top view, an example of a symmetrical variant of the preceding guiding structures.
• the Y-shaped end is optically connected to a microguide 50 of the first part either directly (that is to say the first and the second part are in contact) or via an intermediate element which perhaps as shown in this figure a free space.
• This type of symmetrical variant also makes it possible to obtain from a profile wave
• Gaussian a wave with a wider profile.
• Another source S is thus represented in dotted lines, disposed at the other end of the guiding structure.
• couplers arranged between the sources and the guide structure allowing to take part of the light wave to transmit it for example to detectors D, D '.
• FIG. 10 illustrates yet another example of a guiding structure applied to the production of a demultiplexer.
• the source S emits towards a microguide 3 of the second part 2, a light wave having the central wavelengths ⁇ X ⁇ 2 , ... ⁇ i, ... ⁇ n .
• the output of the microguide 3 has the Y-shaped end 5 and is opposite a dispersive element 60 of the transmissive type such as a holographic network or an acousto-optical element.
• This element makes it possible to transmit to the first part 1 which comprises as many microguides G x , ... Gi, ... G n as of central wavelengths, a light wave of distinct wavelength ⁇ i at each microguide Gi .
• n light waves of central wavelengths ⁇ x , ⁇ 2 , ... ⁇ i, ... ⁇ n are obtained.
• the realization of the guiding structure of the invention can be obtained by all the techniques capable of manufacturing integrated optical components and in particular by the techniques for producing the integrated optics by ion exchange in the glass, or by deposition by hydrolysis obtained via an FHD flame (called in English terminology “Flame Hydrolysis Deposition”) or by chemical vapor deposition PECVD (called in English terminology “Plasma Enhanced Chemical Vapor Deposition”) on silica, on silicon, or else on polymers.
• Y shapes are produced in the xz plane, but as we have seen previously the Y shape can also be made in the yz plane or in the xz and yz planes. so as to form a three-dimensional Y.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Integrated Circuits (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=8861160

Family Applications (1)

Country Status (4)

Family Cites Families (6)

• 2001
  • 2001-03-15 FR FR0103526A patent/FR2822241B1/fr not_active Expired - Fee Related
  • 2001-05-04 US US09/848,542 patent/US20020131714A1/en not_active Abandoned
• 2002
  • 2002-03-15 EP EP02713026A patent/EP1386186A2/de not_active Withdrawn
  • 2002-03-15 WO PCT/FR2002/000926 patent/WO2002075386A2/fr not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events