FR2863716A1 - Micro-opto-electro-mechanical system type optical micro-system, has optical structures with reference zones that are situated opposite to contact zones of mechanical structure, where reference zones are in stops on respective contact zones - Google Patents

Abstract

The micro-system has a mechanical structure (5) including contact zones (6, 7) forming stops. Optical structures (1, 3) have reference zones (8, 9) that are situated opposite to the zones (6, 7), at determined distances from axes of waveguides (2, 4) of the optical structures, respectively. The zones (8, 9) are in stop on the respective zones (6, 7).

Description

OPTICAL MICRO-SYSTEM WITH MECHANICAL STOPS

  POSITIONING OF OPTICAL STRUCTURES

DESCRIPTION 5 TECHNICAL FIELD

  The present invention relates to an optical microsystem of the MOEMS (Micro-Opto-Electro-Mechanical Systems) type, that is to say an integrated component comprising mobile mechanical parts associated with optical structures or providing a optical function. In this type of component, the moving parts must often be positioned very precisely with respect to each other with a precision of the order of a micrometer and sometimes less.

  The invention particularly relates to MOEMS type components comprising a mobile guiding optical structure.

  The fields of application concerned in particular are those of mechanical sensors, optical sensors and optical telecommunications. The mechanical sensors can thus benefit from the advantages of an optical signal processing, possibly directly integrated on the chip. This configuration also allows to deport the electronics by carrying the signal in optical form, which can be very interesting if the sensor operates in a hostile environment (electromagnetic field, risk of explosion, high temperature, etc.). Optical sensors can take advantage of the advantages provided by mechanics: very low crosstalk (or crosstalk in English), insensitivity to wavelength and polarization. Optical telecommunications can benefit from the invention for switches, variable attenuators, optical routers, etc.

STATE OF THE PRIOR ART

  The components of the MOEMS type are integrated components using mobile mechanical parts associated with optical structures or providing an optical function, for example a micro-mirror. Other embodiments comprise mobile mechanical parts associated with an optical structure which may be a guiding structure (optical fiber, planar optical guide, etc.) or non-guiding structure (micro-lens, etc.).

  When optical fibers are used, they are generally fixed on mobile mechanical structures of the MEMS type. These solutions take advantage of MEMS technology now well established. However, this approach suffers from a high cost due to encapsulation which is complicated by the precise positioning of the fibers on the mechanical parts. Indeed, this precise positioning step requires specific and particularly powerful instrumentation.

  The solutions that implement mobile planar optical guides are very interesting since they allow the realization of all functions (optical, mechanical, electrical, etc.) on the same substrate thanks to the collective manufacturing techniques derived from microelectronics. .

  The document [1]: Bistable 2 X 2 and Multistable 1 X 4 Micromechanical Fiber-optic Switches on Silicon by P. KOPKA et al., MOEMS 99, Mainz, Germany, August 30, September 1999, describes the state well. of the art constituted by a switch 1 XN thermal actuator.

  In the case of mobile planar optical guides, the state of the art is well represented by the following documents: [2]. Optical MEMS Devices Based on Moving Waveguides by E. OLLIER, IEEE Journal on Selected Topics on Quantum Electronics, Vol. 8, No. 1, January-February 2002, which relates to a 1 x N switch and vibration sensor made in SiO2 / Si technology, with electrostatic actuator for the switch; [3]: GaAs-based Micromechanical Waveguide Switch from O. BLUM et al., Optical MEMS Conference, Kauai, Hawaii (USA), August 22-24, 2000, which refers to a 1 x 2 switch in GaAs technology, with actuator electrostatic; [4]: Development of Prototype Micromechanical Optical Switch of M. HORINO et al., JSME International Journal, Series C, Vol. 41, No. 4, 1998, which relates to a switch made of SiO2 / Si technology with electromagnetic actuator; [5]: Bottlenecks of Opto-MEMS by D. HARONIAN, Micro-Optoelectromechanical Systems, Proceedings of SPIE, Vol. 4075, 2000, which relates to sensors made with SiO2 / Si3N4 / SiO2 guides; [6]: Silicon-on insulator (SOI) movable integrated optical waveguide technology of S.C. KAN et al., Sensors and Actuators A 54 (1996) pages 679-683, which relates to sensors made with SOI technology; [7]: E. OLLIER Optical MEMS based on moving micro-mechanical waveguides: technologies and component developments, IPR 2002, Vancouver, BC, Canada, 17-19 July 2002 which compares switches made from mobile optical guides.

  The devices of the state of the art have a disadvantage concerning the relative positioning of the mobile optical guide with respect to one of the fixed optical guides. In general, the problem is to position a mobile optical structure with respect to another optical structure (mobile or fixed) with excellent accuracy. The accuracy is determined by the difference between the axes of the optical guides and the angle made by one optical guide relative to the other.

  Some applications can do without a precise positioning but others require a very precise positioning of the mobile structure relative to the fixed structure, for example for optical loss constraints. This is particularly the case for the switches disclosed in documents [1] to [4].

  In the case of document [1], the positioning of the mobile structure (the mechanical structure supporting the optical fiber) is achieved by placing the mobile optical fiber in a notch also supporting the fixed optical fiber. This approach is very effective to obtain an excellent alignment but it requires to implement an actuator capable of imposing a movement in two directions: parallel to the plane of the fibers (switching) and perpendicular to the plane of the fibers (notch change).

  In the case of documents [2], [3] or [4], the positioning of the movable guide is ensured by placing it in contact on a mechanical stop engraved in the layers including the optical guides. In this approach, the problem is that the quality of the positioning depends directly on the quality of the photolithography techniques used to manufacture the mechanical structures, including the mechanical stop. These techniques necessarily induce a difference between the desired dimension and the score obtained (difference which will be called overstitching thereafter). This difference is induced by the manufacturing process, the inhomogeneity of etching in the etched thickness, the non-uniformity of the wafers worked, etc. For the geometries and layer thicknesses conventionally used for these integrated optical components (approximately 5 to 30 μm), this overgrafting is generally greater than one micrometer, which is incompatible for certain applications. The effect of this overgraft is that, once abutting, the movable guide is not correctly positioned relative to the fixed guide.

  In this type of component, it is also possible to position the movable optical guide relative to the selected fixed guide by active control of the position of the movable guide, that is to say by using an actuator which allows the displacement of the mobile structure. But passive positioning is often more appreciated, for example for reasons of power consumption, temperature stability or vibration, compared to shocks, etc.. The problem that arises is to position, in a given plane, a mobile optical structure (the one of which we want to control the positioning) with respect to another optical structure (fixed or mobile) by means of a contacting this movable structure against a mechanical part (which acts as a stop) with excellent accuracy and in particular independently of possible etching defects related to the manufacturing process.

  PRESENTATION OF THE INVENTION The invention makes it possible to position with excellent precision two optical structures, at least one of which is mobile, independently of the overgraft due to the manufacturing technique of the mechanical parts.

  In the simplest case, the invention consists in providing, in addition to the two optical structures to be positioned relative to one another, a mechanical stop and to relate mechanical references related to each of the optical structures with the references of the mechanical stop, with conditions on the geometry of the references which make it possible to be independent of the surgravure.

  The subject of the invention is therefore a micro-system comprising at least a first optical structure and at least a second optical structure, each optical structure comprising at least one optical element associated with at least one determined reference zone of this optical element, the micro-system also comprising at least one mechanical structure comprising at least a first abutment contact zone and at least one second abutment contact zone, the first contact zone of the mechanical structure being able to abut the reference zone abutment of the first optical structure and the second contact zone of the mechanical structure being able to receive in abutment the reference zone of the second optical structure to cause a desired positioning of the optical element of the first optical structure with respect to the optical element of the second optical structure.

  The mechanical structure may comprise at least a first abutment contact zone and a second abutment contact zone located in the same plane.

  Advantageously, at least two structures among the following three structures: the first optical structure, the second optical structure and the mechanical structure are movable relative to the remaining structure among these three structures.

  The micro-system may comprise passive means allowing at least the abutment of a contact zone of the mechanical structure with a corresponding reference zone of an optical structure. These passive means may be means using a stress phenomenon in a material to allow said abutment. This phenomenon of constraints can be buckling.

  The micro-system may comprise active means enabling at least the abutment of a contact zone of the mechanical structure with a corresponding reference zone of an optical structure. These active means may comprise an electrostatic actuator.

  The desired positioning may consist of aligning an optical element of the first optical structure with an optical element of the second optical structure. According to an alternative embodiment, the first optical structure has an optical element, the second optical structure has a first optical element and a second optical element not aligned with the first optical element, the micro-system comprises a first mechanical structure and a second structure. mechanical arranged so that: - the first mechanical structure has a first contact zone capable of receiving a first reference zone of the first optical structure in abutment, and a second contact zone capable of receiving a first reference zone of the second optical structure for causing the alignment of the optical element of the first optical structure with the first optical element of the second optical structure; - the second mechanical structure having a first contact zone able to receive a second reference area in abutment of the first optical structure, and a second contact zone capable of receiving in abutment a second reference zone of the second optical structure to cause alignment of the optical element of the first optical structure on the second optical element of the second optical structure.

  The desired positioning may, of course, consist of the reverse in a determined misalignment of an optical element of the first structure with an optical element of the second structure. This misalignment determined can in particular allow the division of the intensity of a light beam.

  The desired positioning may consist of optically connecting two non-aligned optical elements of an optical structure with two non-aligned optical elements of another optical structure. According to an alternative embodiment, the micro-system comprises a first optical structure comprising a first optical element and a second optical element not aligned with each other, a second optical structure comprising four optical connection elements and a third optical structure comprising a first optical element. and a second optical element not aligned with each other, the four optical connection elements of the second optical structure being arranged for: in a first operating state, optically connecting the first optical element and the second optical element of the first optical structure respectively to the first optical element and the second optical element of the third optical structure, - in a second operating state, optically connecting the first optical element and the second optical element of the first optical structure respectively to the second optical element and the second optical element. first optical element of the third optical structure, the microsystem also comprising a first mechanical structure, a second mechanical structure, a third mechanical structure and a fourth mechanical structure arranged so that: the first mechanical structure has a first contact zone capable of receiving abutting a first reference zone of the first optical structure, and a second contact zone capable of receiving a first reference zone of the second optical structure in abutment, the second mechanical structure has a first contact zone able to receive abutment a second reference zone of the second optical structure, and a second contact zone able to receive a first reference zone of the third optical structure in abutment, to obtain one of the said operating states; the third mechanical structure has a third first contact zone ap to receive a second reference zone of the first optical structure in abutment, and a second contact zone capable of receiving a third reference zone of the second optical structure in abutment, the fourth mechanical structure has a first contact zone able to receiving in abutment a fourth reference zone of the second optical structure, and a second contact zone adapted to receive a second reference zone of the third optical structure in abutment, to obtain the other of said operating states.

  The first and the second mechanical structure or the third and the fourth mechanical structure can be mechanically linked to each other.

  Said optical elements may be elements chosen from guiding configuration optical elements and non-guiding optical elements.

  By way of example, the optical elements having the following configuration are integrated optical guides 30, optical fibers and the non-guiding configuration elements are, for example, lenses, optical sources, sensors

BRIEF DESCRIPTION OF THE DRAWINGS

  The invention will be better understood and other advantages and features will become apparent on reading the following description, given by way of non-limiting example, accompanied by the appended drawings in which: FIG. 1 is a partial sectional view a first variant of a micro-system according to the invention; FIGS. 2A and 2B are fragmentary and sectional views of a second variant of the micro-system according to the invention, respectively before the linking of the references and after the linking of the references; FIGS. 3A and 3B are partial views in section of a third variant of the micro-system according to the invention, respectively before and after the linking of the references; FIGS. 4A and 4B are partial views in section of a fourth variant of the micro-system according to the invention, respectively before and after the linking of the references; FIGS. 5A to 5C are partial and sectional views of a fifth variant of the micro-system according to the invention at different stages of its use; FIGS. 6A to 6C are partial and sectional views of a sixth variant of the micro-system according to the invention at different stages of its use; FIGS. 7A to 7E illustrate a first method of manufacturing a micro-system according to the present invention; FIGS. 8A and 8B illustrate a second method of manufacturing a micro-system according to the present invention.

  DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS A first variant of a micro-system according to the invention is shown, in partial view and in section, in FIG.

  The micro-system comprises a first optical structure 1 comprising a planar waveguide 2 and a second optical structure 3 comprising a planar waveguide 4. Each optical structure presents to the other optical structure an end of the waveguide that she supports. The micro-system also comprises a mechanical structure 5 which comprises, in this embodiment, two contact areas forming abutment 6 and 7 located at different levels. Each of these contact zones 6 and 7 constitutes a mechanical reference.

  The optical structure 1 comprises a reference zone 8 located opposite the contact zone 6 and at a determined distance d1 from the axis of the waveguide 2. The optical structure 3 comprises a reference zone 9 situated in vis-à-vis the contact area 7 and at a determined distance d2 from the axis of the waveguide 4.

  Figure 1 shows the micro-system while the waveguides 2 and 4 are in alignment. The reference zone 8 is then abutting on the contact zone 6 and the reference zone 9 is then abutting on the contact zone 7. The distance separating the plane containing the contact zone 7 from the plane containing the contact zone 6 being called dM, the mechanical references of the micro-system correspond to the relation: dl + dM = d2.

  At least two of the structures among the optical structures and the mechanical structure are mobile with respect to the rest of the micro-system. If the mechanical structure is fixed, then the two optical structures are movable and are brought into abutment on the mechanical structure. If one of the optical structures is fixed, then the mechanical structure is brought against the fixed optical structure and the second optical structure is brought into contact with the mechanical structure to obtain the alignment of the waveguides 2 and 4. If the three structures are movable, the mechanical structure can be brought against the two mobile optical structures until contacts with the optical structures are obtained.

  The linking of the references formed by the contact zones 6 and 7 and the zones 8 and 9 can be carried out either passively during the manufacture of the micro-system (for example by using the phenomena of stress in the materials ), or actively, after the manufacture of the micro-system (eg via an actuator).

  FIGS. 2A and 2B illustrate the case of linking the references in a passive manner. The variant shown is an advantageous configuration that uses stress phenomena in materials that can lead to the buckling of mechanical structures. The linking of the references is obtained thanks to the buckling of a structure during the manufacture of the component.

  The micro-system shown in Figures 2A and 2B comprises a first optical structure 11 which is movable and a second optical structure 13 which is fixed. The optical structure 11 comprises a planar waveguide 12 and a reference zone 18. The optical structure 13 comprises a planar waveguide 14 and a reference zone 19. The micro-system also comprises a mechanical structure 15 having two contact areas forming abutment: the contact areas 16 and 17 located respectively vis-à-vis the reference areas 18 and 19. The mechanical structure 15 is connected to the micro-system by flexible connection means 151 and 152 represented symbolically . These flexible connection means may be beams or a membrane. Reference numeral 10 denotes a buckling element of the structure, shown in the non-flambé state.

  FIG. 2A, which is a view before the connection of the references shows that there is an offset D between the axes of the waveguides 12 and 14.

  The linking of the mechanical references is carried out as follows. The buckling of the element 10 (see FIG. 2B) causes the mechanical structure 15 to be pressed against the optical structure 13 by contacting the contact zone 17 on the reference zone 19. Next, the optical structure 11 is pushed to the mechanical structure 15 until the reference zone 18 is brought into contact with the contact zone 16. The alignment of the axes of the waveguides 12 and 14 is then obtained independently of the overgrading or defects of the engraving that can exist.

  FIGS. 3A and 3B illustrate the case of actively connecting references. The connection can be obtained using an electrostatic actuator (in the case of FIGS. 3A and 3B), electromagnetic, thermal or by using the phenomena of thermal stresses in the materials.

  The micro-system shown in Figures 3A and 3B comprises a first optical structure 21 which is movable and a second optical structure 23 which is fixed. The optical structure 21 comprises a planar waveguide 22 and a reference zone 28. The optical structure 23 comprises a planar waveguide 24 and a reference zone 29. The micro-system also comprises a mechanical structure 25 having two contact areas forming abutment: the contact areas 26 and 27 located respectively vis-à-vis the reference areas 28 and 29. The mechanical structure 25 is connected to the micro-system by flexible connection means 251 and 252 represented symbolically . These flexible connection means may be beams or a membrane.

  The micro-system also comprises electrodes enabling the application of a potential difference: the electrode 253 integral with the mechanical structure 25 and the electrode 254 integral with the rest of the micro-system. Figure 3A shows the micro-system while the voltage across the electrodes 253 and 254 is zero. There is then a shift D between the axes of the waveguides 22 and 24.

  The linking of the mechanical references is carried out as follows. The application of a potential difference V between the electrodes 253 and 254 (see FIG. 3B) causes the appearance of an electrostatic force which causes the mechanical structure to be pressed against the optical structure 23 by contacting the the contact zone 27 on the reference zone 29. Then, the optical structure 21 is pushed towards the mechanical structure 25 until the contact zone 28 is brought into contact with the contact zone 26. The axes of the waveguides 22 and 24 are then obtained independently of the surgravure that may exist.

  FIGS. 4A and 4B illustrate the case of another connection of the references passively. This is a simplified configuration compared to that illustrated by FIGS. 2A and 2B.

  The micro-system shown in Figures 4A and 4B comprises a first optical structure 31 which is movable and a second optical structure 33 which is fixed. The optical structure 31 comprises a planar waveguide 32 and a reference zone 38. The optical structure 33 comprises a planar waveguide 34 and a reference zone 39. The micro-system also comprises a mechanical structure 35 which is a structure capable of flaming by itself (in the form of a beam or membrane). The lower face of the mechanical structure 35 incorporates in the same plane two abutting contact areas: the zones 36 and 37 of the mechanical structure 35 located respectively vis-à-vis the reference areas 38 and 39.

  FIG. 4A, which is a view before connecting the references, shows that there is an offset D between the axes of the waveguides 32 and 34.

  The linking of the mechanical references is as follows (see Figure 4B). The buckling of the mechanical structure 35 causes the contact zone 37 to come into contact with the reference zone 39. Next, the optical structure 31 is pushed towards the mechanical structure 35 until the contact zone is brought into contact with each other. reference 38 on the contact zone 36. The alignment of the axes of the waveguides 32 and 34 is then obtained independently of the overgraft that may exist.

  The present invention can be very advantageously applied to the integrated multichannel optical switch and switch system disclosed in FR-A-2,660,444, corresponding to U.S. Patent No. 5,078,514.

  FIGS. 5A to 5C illustrate the operation of a fifth variant of the micro-system according to the invention, this fifth variant consisting of a 1 × 2 switch.

  The micro-system shown in FIGS. 5A to 5C comprises a first optical structure 41 which is mobile and a second optical structure 43 which is fixed. The optical structure 41 comprises a planar waveguide 42 and two opposite reference areas 481 and 482. The optical structure 43 comprises two planar waveguides 441 and 442 and two opposite reference areas 491 and 492. The optical structure 41 has an end of the waveguide 42 at the ends of the waveguides 441 and 442 of the optical structure 43.

  The micro-system also comprises two mechanical structures 451 and 452 flanking the ends of the optical structures 41 and 43 and each having in this example a flat face to the optical structures. Of course, one could quite consider, without departing from the scope of the invention, any other type of contact area and in particular non-planar areas. The mechanical structure 451 has two abutment contact zones: the contact zone 453 situated opposite the reference zone 481 of the optical structure 41 and the contact zone 454 located opposite the reference zone 491 of the optical structure 43. The mechanical structure 452 has two abutting contact zones: the contact zone 455 situated opposite the reference zone 482 of the optical structure 41 and the contact zone 456 located opposite the reference zone 492 of the optical structure 43. The mechanical structures 451 and 452 are connected to the micro-system by unrepresented flexible connection means.

  In this micro-system, the optical guide 42 must be aligned opposite one of the two optical guides 441 and 442. For this, the optical guide 42 and the axes of the optical guides 441 and 442 are arranged at determined distances from the zones reference of their optical structure. By way of example, since 1 is the width of the optical structure 41, the axis of the optical guide 42 is located at a distance 1/2 from the reference areas 481 and 482. In this case, the axis of the guide Wave 441 is located at a distance 1/2 from reference area 491 and the axis of waveguide 442 is at a distance 1/2 from reference area 492.

  Figure 5A shows the micro-system before linking the references. The optical structure 41 is substantially centered on the optical structure 43.

  FIG. 5B shows the reference linking of the mechanical structures 451 and 452 with the references of the optical structure 43. The mechanical structures 451 and 452 are pressed onto the optical structure 43, which brings the zone into contact with each other. contact 454 with the reference zone 491 and contacting the contact zone 456 with the reference zone 492.

  FIG. 5C shows the connection of a reference of the mechanical structure 451 with a reference of the optical structure 41. The optical structure 41 is pressed onto the mechanical structure 451, for example by virtue of an electrostatic force, which causes the bringing the contact zone 453 into contact with the reference zone 481. The alignment of the axes of the waveguides 42 and 441 is then obtained independently of the overgraft that may exist.

  From this position, the waveguide 42 can be switched to be aligned with the waveguide 442. For this, it is sufficient to press the optical structure 41 on the mechanical structure 452, which causes the contacting of the contact area 455 with reference area 482.

  FIGS. 6A to 6C illustrate the operation of a sixth variant of a micro-system according to the invention, this sixth variant being constituted by a 2 × 2 switch making it possible, for example, to perform insertion / extraction functions.

  The micro-system shown in FIGS. 6A to 6C comprises a first optical structure 100, a second optical structure 200 and a third optical structure 300, substantially aligned. The optical structures 100 and 300 are fixed while the optical structure 200 is movable preferably transversely to the alignment direction. The optical structures 100 and 300 each comprise two optical guides, respectively 101, 102 and 301, 302, separated by the same distance. The optical structures 100 and 300 present towards the center of the microsystem one end of each optical guide they have.

  The optical structure 200 comprises four waveguides: the waveguides 201, 202, 203 and 204 which extend from the end of the optical structure 200 facing the optical structure 100 to the end of the optical structure 200 facing the optical structure 300. FIG. 6A shows that the optical guide 201 can ensure the optical connection between the optical guide 101 and the optical guide 301, the optical guide 203 can ensure the optical connection between the optical guide 101 and the optical guide 302, the optical guide 202 can provide the optical connection between the optical guide 102 and the optical guide 302, the optical guide 204 can ensure the optical connection between the optical guide 102 and the otic guide 301.

  The micro-system also comprises four mechanical structures: the mechanical structures 50 and 60 flanking the neighboring ends of the optical structures 100 and 200, and the mechanical structures 70 and 80 flanking the adjacent ends of the optical structures 200 and 300. All these mechanical structures are mobile and have the optical structures of planar faces, in these examples although, as we have seen previously, this is not limiting. The mechanical structures 50 and 70 on the one hand and the mechanical structures 60 and 80 on the other hand can be mechanically bonded to each other and form respectively a single mechanical structure.

  The optical structure 100 has a reference zone 103 facing the mechanical structure 50 and a reference zone 104 facing the mechanical structure 60. The distance separating the waveguide 101 from the reference zone 103 is dl. The distance separating the waveguide 102 from the reference zone 104 is d2.

  The optical structure 300 has a reference zone 303 facing the mechanical structure 70 and a reference zone 304 facing the mechanical structure 80. The distance separating the waveguide 301 from the reference zone 303 is dl. The distance separating the waveguide 302 from the reference zone 304 is d2. The design of the micro-system is such that the waveguide 101 is aligned with the waveguide 301 and the waveguide 102 is aligned with the waveguide 302. Alignment of two optical elements is understood to be , and in particular two waveguides, the fact that the respective ends of these elements are facing even if the rest of these elements are not in the same axis.

  The optical structure 200 has a reference zone 205 facing the mechanical structure 50, a reference zone 206 facing the mechanical structure 60, a reference zone 207 facing the mechanical structure 70 and a reference zone 208. opposite the mechanical structure 80. The distance separating the waveguide 201 from the reference zones 205 and 207 is dl. The distance separating the waveguide 202 from the reference zones 206 and 208 is d2-do, where d is the distance separating a right guide from the adjacent curved guide at each end of the optical structure 200. Thus, do is the distance separating the waveguide 201 of the guide 203 and the waveguide 202 of the waveguide 204 at the end of the optical structure 200 facing the optical structure 100. Similarly, do is the distance separating the guide from waveguide waveguide 204 and waveguide waveguide 202 at the end of optical structure 200 facing optical structure 300.

  The distance correspond corresponds to the amplitude of the possible displacement of the optical structure 200, between the plane defined by the reference zone 103 (respectively 303) and the plane defined by the reference zone 104 (respectively 304). The width of the optical structure 200 is therefore equal to the width of the optical structures 100 (respectively 300) minus the distance do, at least at the corresponding reference areas.

  The mechanical structure 50 has a contact zone 51 opposite the reference zone 103 of the optical structure 100 and a contact zone 52 vis-à-vis the reference zone 205 of the optical structure 200 The mechanical structure 60 has a contact zone 61 vis-à-vis the reference zone 104 of the optical structure 100 and a contact zone 62 vis-à-vis the reference zone 206 of the optical structure. 200. The mechanical structure 70 has a contact zone 71 opposite the reference zone 207 of the optical structure 200 and a contact zone 72 vis-à-vis the reference zone 303 of the structure The mechanical structure 80 has a contact zone 81 opposite the reference zone 208 of the optical structure 200 and a contact zone 82 vis-à-vis the reference zone 304 of the optical structure 300.

  Figure 6A shows the micro-system before linking references. FIG. 6B shows the micro-system after linking references to obtain the state called bar-state. FIG. 6C shows the micro-system after linking references to obtain the so-called cross-state state.

  In order to obtain the operating state shown in FIG. 6B, the mechanical structures 50 and 70 are brought into abutment on the optical structures 100 and 300. This causes the contact zone 51 of the mechanical structure 50 to come into contact with the reference zone 103 of the optical structure 100 and contacting the contact zone 72 of the mechanical structure 70 with the reference zone 303 of the optical structure 300. Then, the optical structure 200 is brought into abutment on the structures mechanical and 70. This causes the contact zone 52 of the mechanical structure 50 to come into contact with the reference zone 205 of the optical structure 200 and the contact zone 71 of the mechanical structure 70 to come into contact with the reference zone 207 of the optical structure 200. The optical guides 101, 201 and 301 are then aligned and a signal can be conveyed between the optical guides 101 and 301. The optical guides 102, 202, and 302 are also aligned and an optical signal can be conveyed between the optical guides 102 and 302.

  To obtain the operating state shown in FIG. 6C, the mechanical structures 60 and 80 are brought into abutment on the optical structures 100 and 300, the mechanical structures 50 and 70 being able, for example, to be raised. This causes the contact zone 61 of the mechanical structure 60 to come into contact with the reference zone 104 of the optical structure 100 and the contact zone 82 of the mechanical structure 80 to come into contact with the reference zone 304. of the optical structure 300. Then, the optical structure 200 is brought into abutment on the mechanical structures 60 and 80. This causes the contact zone 62 of the mechanical structure 60 to come into contact with the reference zone 206 of the structure 200 and contacting the contact zone 81 of the mechanical structure 80 with the reference zone 208 of the optical structure 200. The optical guides 101, 302 are then optically connected through the optical guide 203 and the optical guides 102. and 301 are optically connected through optical guide 204.

  The displacements of the moving elements (mechanical structures 50, 60, 70, 80 and optical structure 200) can be obtained by means of electrostatic forces.

  The micro-system according to the invention can be realized by implementing the conventional techniques of collective fabrication used in the fields of microelectronics and microtechnologies: layer deposition, photolithography, anisotropic or isotropic etchings, metal deposits, etc. All existing integrated optical technologies can benefit from the invention, for example silica on silicon, polymers, InP, SOI, GaAs, etc. Two possible methods of manufacture for a micro-system according to the invention will now be described. They can be applied to the switch disclosed in the document FR-A-2,660,444 cited above.

  Figs. 7A-7E are sectional views illustrating a first method of manufacturing a micro-system according to the present invention. This method of manufacture makes it possible to obtain a passive positioning of the mechanical structure thanks to a buckling effect.

  FIG. 7A shows a silicon substrate 400 on which a silica layer 401 and a silica layer 402 having a higher index than that of the layer 401 have been successively deposited. The layer indices are for example controlled by doping the layer 401. silica with for example phosphorus, boron or germanium. By way of example, the layer 401 has a thickness of 10 μm and the layer 402 has a thickness of 5 μm. The layer 402 is then etched to produce the optical guides. FIG. 7B shows a first optical guide 403 and a second optical guide 404. The optical guides are thus seen in cross section, one end of the optical guide 403 being situated approximately at one of the ends of the optical guide 404 so that, in a given state of operation of the micro-system obtained, these ends of the optical guides can be put in vis-à-vis.

  Next, a layer 405 of SiO 2 is deposited on the layer 401 by covering the guides 403 and 404 (see FIG. 7C). The layer 405 may have a thickness of 10 μm.

  The layers 401 and 405 are then etched to the substrate 400 to define a mobile optical structure 406 comprising the optical guide 404 and a reference zone 407 (see FIG. 7D), a fixed optical structure 408 comprising the optical guide 403 and a reference zone 409, a movable mechanical structure 410 comprising a face 411 provided with at least one contact zone, and a flaming beam member 412 for passive positioning of the mechanical structure 410.

  FIG. 7E shows the microsystem obtained after liberation of the mobile structures by isotropic etching of the substrate. Optionally, a sacrificial layer may be provided. This etching 413 makes it possible to make the optical structure 406, the mechanical structure 410 and the element 412 mobile.

  Figs. 8A and 8B are cross-sectional views illustrating a second method of manufacturing a micro-system according to the present invention. This embodiment makes it possible to obtain an active positioning of the mechanical structure by means of an electrostatic actuator.

  The first manufacturing steps of this micro-system are identical to the steps represented by FIGS. 7A to 7C and are therefore not illustrated.

  The device obtained at the end of the step represented in FIG. 7C undergoes a step of etching the layers 401 and 405, up to the substrate 400, to delimit (see FIG. 8A) as for the first mode of manufacture, a mobile optical structure 406 comprising the optical guide 404 and a reference zone 407, an optical structure 408 comprising the optical guide 403 and a reference zone 409, and a movable mechanical structure 410 comprising a face 411 provided with at least one zone of contact. The etching also provides a trench 414 for producing an electrostatic actuator for the mechanical structure 410.

  FIG. 8B shows the microsystem obtained after liberation of the mobile structures by isotropic etching of the substrate. Optionally, a sacrificial layer may be provided. This etching 413 makes it possible to make the optical structure 406 and the mechanical structure 410 mobile.

  The electrodes of the actuator are then deposited (see, for example, references 253 and 254 of FIG. 3A). These electrodes are obtained by evaporation or sputtering (for example of a metal such as aluminum or a metal multilayer such as Ti-Ni-Au) produced through a mechanical mask on walls opposite the trench. 414.

  The invention has been described above with reference to optical guides. However, it also applies to other guiding configurations such as optical fibers or non-guiding as microlenses.

  The description also related to positioning in the plane of the optical guides. However, the positioning can be carried out in other directions, for example in the direction perpendicular to the plane of the optical guides, taking advantage of the homogeneity of thickness of the layers deposited to produce the optical guides.

Claims (15)

  A micro-system comprising at least a first optical structure (1) and at least a second optical structure (3), each optical structure (1, 3) comprising at least one optical element (2, 4) associated with at least one determined reference zone (8, 9) of this optical element (2, 4), the micro-system also comprising at least one mechanical structure (5) comprising at least a first contact zone (6) forming a stop and at least one second contact zone (7) forming a stop, the first contact zone (6) of the mechanical structure (5) being able to receive in abutment the reference zone (8) of the first optical structure (1) and the second zone contacting (7) the mechanical structure (5) being able to abut the reference region (9) of the second optical structure (3) to cause a desired positioning of the optical element (2) of the first structure optical (1) with respect to the optical element (4) of the second optical structure (3).   2. Micro-system according to claim 1, characterized in that the mechanical structure (35) comprises at least a first contact zone (36) forming a stop and a second contact zone (37) forming a stop located in the same plane.   3. Micro-system according to one of claims 1 or 2, characterized in that at least two structures among the following three structures: the first optical structure (1,11), the second optical structure (3,13) and the mechanical structure (5, 15) is movable with respect to the remaining structure among the three structures.   4. Micro-system according to any one of claims 1 to 3, characterized in that it comprises passive means (10) allowing at least the abutment of a contact zone (17) of the mechanical structure ( 15) with a corresponding reference area (19) of an optical structure (13).   5. Micro-system according to claim 4, characterized in that the passive means are means using a stress phenomenon in a material to allow said abutment.   6. Micro-system according to claim 5, characterized in that said stress phenomenon is buckling.   7. Micro-system according to one of claims 1 to 3, characterized in that it comprises active means for at least the abutment of a contact zone (27) of the mechanical structure (25) with a corresponding reference area (29) of an optical structure (23).   8. Micro-system according to claim 7, characterized in that the active means comprise an electrostatic actuator.   Micro-system according to any one of the preceding claims, characterized in that the desired positioning consists of the alignment of an optical element (42) of the first optical structure (41) with an optical element (441, 442 ) of the second optical structure (43).   Micro-system according to claim 9, characterized in that the first optical structure (41) has an optical element (42), the second optical structure (43) has a first optical element (441) and a second optical element (44). 442) not aligned with the first optical element (441), the micro-system comprises a first mechanical structure (451) and a second mechanical structure (452) arranged so that: the first mechanical structure (451) has a first zone of contact (453) able to receive in abutment a first reference area (481) of the first optical structure (41), and a second contact area (454) able to receive in abutment a first reference area (491) of the second optical structure (43) for causing alignment of the optical element (42) of the first optical structure (41) with the first optical element (441) of the second optical structure (43), - the second mechanical structure ( 45 2) has a first contact zone (455) capable of receiving a second reference zone (482) of the first optical structure (41) in abutment and a second contact zone (456) capable of receiving a second zone in abutment. reference (492) of the second optical structure (43) for causing alignment of the optical element (42) of the first optical structure (41) on the second optical element (442) of the second optical structure (43) .   11. Micro-system according to any one of claims 1 to 8, characterized in that the desired positioning consists of a specific misalignment of an optical element of the first structure and an optical element of the second structure.   12 Micro-system according to any one of claims 1 to 8, characterized in that the desired positioning consists of optically connecting two optical elements (101, 102) not aligned with each other of an optical structure (100) with two optical elements (301, 302) non-aligned with each other of another optical structure (300).   13. Micro-system according to claim 12, characterized in that it comprises a first optical structure (100) comprising a first optical element (101) and a second optical element (102) not aligned with each other, a second optical structure ( 200) comprising four optical connection elements (201 to 204) and a third optical structure (300) comprising a first optical element (301) and a second optical element (302) not aligned with each other, the four optical connection elements of the second optical structure (200) being arranged for: - in a first operating state, optically connecting the first optical element (101) and the second optical element (102) of the first optical structure (100) respectively to the first optical element (301). ) and the second optical element (302) of the third optical structure (300), - in a second operating state, optically connecting the first optical element (101) ) and the second optical element (102) of the first optical structure (100) respectively to the second optical element (302) and the first optical element (301) of the third optical structure (300), the micro-system also comprising a first mechanical structure (50), a second mechanical structure (70), a third mechanical structure (60) and a fourth mechanical structure (80) arranged so that: - the first mechanical structure (50) has a first contact zone (51) adapted to receive in abutment a first reference zone (103) of the first optical structure (100), and a second contact zone (52) able to receive in abutment a first reference zone (205) of the second optical structure ( 200), the second mechanical structure (70) has a first contact zone (71) capable of receiving a second reference zone (207) of the second optical structure (200) in abutment and a second zone of c ontact (72) able to abut a first reference area (303) of the third optical structure (300) to obtain one of said operating states, - the third mechanical structure (60) has a first contact zone (61) adapted to receive a second reference zone (104) of the first optical structure (100) in abutment and a second contact zone (62) capable of receiving a third reference zone (206) of the second optical structure (200), the fourth mechanical structure (80) has a first contact zone (81) able to receive a fourth reference zone (208) of the second optical structure (200) abutting and a second contact zone (82) adapted to abut a second reference region (304) of the third optical structure (300) to obtain the other of said operating states.   14. Micro-system according to claim 13 characterized in that the first and the second mechanical structure or the third and fourth mechanical structure are mechanically bonded to each other.   15. Micro-system according to any one of the preceding claims, characterized in that said optical elements are elements selected from the optical elements guiding configuration and optical elements non-guiding configuration.