Single lens optical fiber comprising optical fiber cut at 90 DEG at distal end and fused with lens having concave mirror formed on outer surface

Abstract

The present invention relates to a single lens optical fiber including an optical fiber cut at 90 DEG at a distal end and fused with a lens having a concave mirror formed on an outer surface. The invention mainly comprises a lensed optical fiber (1) comprising an optical lens (3), preferably fused to the end of an optical fiber (2) cut into right angles, and the shape of which, in particular the shape of the outer surface (4), is perfectly controlled so that a reflective refractive optical or concave mirror with angular reflection can be realized, therefore, the luminous flux transmitted or received between the optical fiber and the photoelectric component is adapted and optimized.

Description

Technical Field

[0001] The present invention relates to the field of optical fibers for light transmission and / or data transmission, and in particular to lensed optical fibers.

[0002] A lensed fiber is an optical fiber whose one end (called the distal end) is extended by an adapted optical component to reshape the light flux entering or leaving the fiber.

[0003] The present invention also relates to an optical subassembly or OSA, which is a subassembly that combines one or more optoelectronic components and one or more lensed optical fibers.

[0004] The present invention relates to a transmitter subassembly for converting an electrical signal into an optical signal and a receiver subassembly for converting an optical signal into an electrical signal.

[0005] The invention also relates to an optoelectronic module that integrates one or more subassemblies onto an electronic card in a housing.

[0006] The invention also relates to a transceiver module combining a receiver subassembly and a transmitter subassembly sharing common electronic circuitry and a common electronic card, often called a "transceiver", an abbreviation of "transmitter" and "receiver".

[0007] Preferred applications of the invention relate to optoelectronic modules, in particular for use in the aviation, space, defence, transport or medical sectors or in telecommunications, data communications and industry.

[0008] Although described with reference to this preferred application, the present invention may be applied to any system requiring the installation of a lensed fiber. Background Art

[0009] Optical link systems are known that use optoelectronic modules and optical links formed by one or more optical fibers. Each optoelectronic module of a transmitter or receiver is formed by an electronic card, optoelectronic components and their electronic control components, one or more optical fibers that can be cascaded into a ribbon, and optical coupling devices between the one or more optoelectronic components and the one or more optical fibers.

[0010] As an optical coupling device, lensed fibers are known to be used to adapt the light flux between the optical fiber and optoelectronic components. Thus, during transmission, the light flux between a light source or luminous source, such as an LED (light-emitting diode), laser, or VCSEL (vertical cavity surface-emitting laser), and the optical fiber (waveguide) that transmits the light flux is optimized. During reception, the light flux between the optical fiber and the optical receiver (photodiode, etc.) is optimized.

[0011] Patent EP1481274B1 discloses, in an embodiment, an optical fiber called a "pigtail," corresponding to the English term "pigtail," that is, an optical fiber with no connection at one end, called the proximal end, and a distal end fused to a plurality of spliced ​​optical elements, the two spacers of which are in the form of coreless optical fiber sections with a single refractive index, arranged on either side of a gradient refractive index optical lens (GRIN), and terminated by an inclined surface covered by a reflective aspheric surface forming the free end. Alternatively, instead of the inclined surface and the reflective aspheric surface, a curved surface is provided at the end of the distal spacer so that the optical signal directed to the curved surface is redirected. Regardless of the mode adopted, this solution is complex and expensive, and it is not possible to focus the light beam emitted directly from the "pigtail" optical fiber. In fact, regardless of the embodiment proposed in this patent, the optical fiber is always equipped with at least one GRIN lens at its distal end, so that the light beam can be collimated before reaching a plane or concave mirror. In addition, eliminating this GRIN lens will lead to the convergence or parallelization of the light beam, resulting in the defect of light flux loss at the optical fiber input or optoelectronic component.

[0012] U.S. patent application US2021 / 341688 discloses an optical coupling system between an optical fiber and a VCSEL laser. The system includes an optical ferrule comprising a body beveled at approximately 45° at its distal end, an optical fiber aligned with the beveled surface of the body, and concave mirrors formed at the ends of some of the optical fibers. This solution is also complex and has high production costs. In addition, the 45° bevel means additional difficulty in positioning the optical axis emitted by the optical fiber on the beveled surface, because the intersection between the beveled surface of the optical fiber end and the cylindrical outer sheath forming the optical fiber core forms an ellipse. This results in poor accuracy in positioning the concave mirror relative to the optical axis of the optical fiber. In addition, the complexity of positioning the lens relative to the optical axis can result in a longer and therefore more expensive manufacturing setup. Finally, the light flux to or from the VCSEL laser passes through the material of at least one optical fiber, in particular, through the optical fiber's sheath, which complicates the calculation of the light flux's path. Furthermore, this solution does not provide a reference plane for the angular orientation of the lens around the optical fiber axis.

[0013] Therefore, there is a need for an improved lens optical fiber, especially for achieving optical coupling with optoelectronic components, to overcome the above-mentioned disadvantages.

[0014] The present invention aims to meet this need in whole or in part. Summary of the Invention

[0015] To this end, according to one aspect of the present invention, the present invention aims to provide a single lens optical fiber, comprising:

[0016] - an optical fiber having a longitudinal axis (X), the distal end of the optical fiber being a plane perpendicular to the longitudinal axis;

[0017] a primary optical lens having a single refractive index, arranged at the distal end of the optical fiber, and having an outer surface defined by at least a concave portion and a planar portion parallel to the longitudinal axis of the optical fiber or inclined at a non-zero angle to the longitudinal axis of the optical fiber, the optical lens being integrally formed on the distal end of the optical fiber, forming an integral component therewith;

[0018] a mirror matched with at least a portion of the concave portion of the main lens, the mirror being at least partially reflective in at least one given wavelength range, so that at least a portion of the light beam coming from the optical fiber and passing through the main lens is reflected by the mirror to be emitted through the flat portion of the main lens, or conversely, at least a portion of the light beam passing through the flat portion of the main lens and passing through the main lens is reflected by the mirror to be emitted through the optical fiber.

[0019] Here and in the context of the present invention, "concave surface" refers to a surface whose depression is toward the optical fiber.

[0020] Advantageously, the primary optical lens is fused to the optical fiber to form a unitary element.

[0021] According to an advantageous embodiment, the lens fiber comprises an additional optical lens arranged on the surface of the planar portion.

[0022] According to an advantageous configuration, the outer surface of the primary optical lens is further defined by a (e) free end portion having a height greater than or equal to 100 nm.

[0023] According to this configuration and advantageous feature, the outer surface of the primary optical lens is defined by a right parallelepiped having a flat portion on one face and a free end of non-zero height on the other face.

[0024] According to another advantageous embodiment, the outer surface of the primary optical lens is likewise defined by a circular portion at least partially conforming to the outer diameter of the optical fiber.

[0025] Preferably, the thickness (e') of the circular portion is greater than or equal to 100 nm.

[0026] Advantageously, the height of the main lens is less than or equal to the outer radius of the optical fiber.

[0027] Advantageously also, the concave portion of the outer surface of the main lens, and where necessary also further concave portions, is a biconical surface, preferably a biparaboloid.

[0028] Preferably, the material of the main lens and, if necessary, of the additional lens, is transparent in a given wavelength range, preferably between 800 and 1700 nm.

[0029] The primary lens, as well as other materials if desired, can be made of a polymer or transparent glass that is transparent at the wavelength used, preferably between 800 and 1700 nm. The photopolymer resin can be, for example, an epoxy, an acrylate, or a combination thereof, an unsaturated polyester, a urethane, or a sol-gel material. It can also be a thermoplastic resin, such as polyethyleneimine (PEI) or polyamideimide (PAI).

[0030] According to a first variant embodiment, the mirror is a metal layer deposited on the concave portion of the lens, the metal preferably being chosen among Au, Al, Ni, Ag.

[0031] According to a second variant embodiment, the mirror is a dielectric layer reflecting within a given wavelength range.

[0032] According to an advantageous embodiment, the single lens fiber comprises at least one protrusion, preferably two protrusions arranged on either side of the mirror, projecting beyond the free end of the outer surface, the protrusions being intended to form an axial stop with the support for axially positioning the fiber.

[0033] Advantageously, each projection comprises a stop region perpendicular to the longitudinal axis (X) of the optical fiber, said region preferably being planar, thereby ensuring a surface-to-surface abutment as an axial stop.

[0034] Advantageously, the protrusions are made of the same material as the optical lens. Advantageously, these protrusions can be produced during the additive manufacturing process of the optical lens. Alternatively, these protrusions can be printed onto an already formed lens and / or made of a material with different mechanical properties than the lens material. Regardless of the embodiment variant, the geometry of these protrusions must ensure access to the surface of the optical lens for deposition in order to achieve the mirror, so that there is an unoccupied space between the two protrusions arranged on either side of the lens.

[0035] According to an advantageous configuration, the protrusion is realized by a transverse circumscription in the cross section of the lens fiber.

[0036] This or these protrusions make it possible to improve the passive axial positioning of the lens fiber in a groove of its support, in particular a silicon substrate. This makes it possible to correctly position the optical flux relative to the optoelectronic component to which the fiber must be coupled, such as a laser or a photodiode.

[0037] The positioning is advantageously completely passive, thanks to the mechanical stop formed by the projection, without the need for optical signal transmission and complex measuring stages for calibrated positioning.

[0038] Simply detecting the effective mechanical stop, in particular by means of a force sensor or optical observation of the mechanical contact, is sufficient to ensure the desired good axial positioning.

[0039] The protrusions may take different forms, particularly when the optical lens is implemented with an outer surface comprising prisms.

[0040] According to a variant embodiment, the protrusion may have an angular shape extending from the free end of a right prism.

[0041] The present invention also relates to an optical subassembly comprising:

[0042] - at least one single lensed optical fiber as described above,

[0043] - at least one optoelectronic component arranged at a distance from and opposite a planar portion of the primary lens, the planar portion being parallel to the longitudinal axis of the optical fiber or inclined at a non-zero angle to the longitudinal axis of the optical fiber.

[0044] Preferably, the space between the optoelectronic component and the flat portion of the main lens or, if necessary, the additional lens is filled with air, a resin transparent in a given wavelength range, or an adhesive transparent in a given wavelength range.

[0045] According to one multi-channel embodiment, the subassembly comprises:

[0046] - a support comprising a plurality of grooves, preferably V-shaped,

[0047] - a plurality of lens fibers, each positioned and locked in one of the grooves,

[0048] - anti-slip flanges of a plurality of optoelectronic modules arranged on the support, each of the optoelectronic modules being arranged facing and spaced apart from a flat portion of the main lens of one of the optical fibers.

[0049] The invention also relates to an optoelectronic module comprising at least one optical subassembly as described above.

[0050] The present invention finally relates to a method for preparing the single lens optical fiber described above, comprising the following steps:

[0051] i / Positioning the optical fiber on the support,

[0052] ii / cutting at 90°, in particular by cleaving, and preparing the distal end of the optical fiber,

[0053] iii / dipping or immersing the distal end 22 of the optical fiber into a resin of a photopolymer material,

[0054] iv / polymerizing the resin by laser to form an outer surface of the optical lens, the outer surface being defined by at least a concave portion and a planar portion parallel to the longitudinal axis X of the optical fiber,

[0055] v / Depositing an at least partially reflective material on all or part of the concave portion of the outer surface of the lens in order to form the mirror.

[0056] Step i / may be performed before step ii / or step ii / may be performed before step i / .

[0057] The term "preparation" is understood here and in the context of the present invention to mean all conventional surface treatment steps to ensure the desired state of the fiber end face, in particular with high flatness and low roughness, such as by cleaving and / or polishing.

[0058] The term "dipping" is understood here and in the context of the present invention to mean immersing the end of the optical fiber in a bath of photopolymer resin and then removing it from the bath before polymerization of the optical fiber end by capillary action begins in the remaining droplet.

[0059] The term "immersing" herein and in the context of the present invention means submerging the end of the optical fiber in a bath of photopolymer resin and leaving it in the bath during polymerization.

[0060] Step iv / is advantageously carried out by two-photon photopolymerization (2PP).

[0061] The present invention thus essentially comprises a single lensed optical fiber with an optical lens preferably fused to the end of the optical fiber cut at a right angle, the shape of the optical lens, in particular the shape of its outer surface, being perfectly controllable, making it possible to realize a reflective-refractive optical element or a concave mirror with angular reflection in order to adapt and optimize the light flux entering or exiting in transmitting or receiving mode between the optical fiber and the optoelectronic component.

[0062] The optical lens is integrally formed at the distal end of the optical fiber, forming an integral element with the optical fiber, advantageously by photopolymerization (preferably by laser) on the optical fiber of a material transparent to the wavelength used, by additive printing or 3D prior to the reflective treatment, thereby obtaining the reflective-refractive optical surface that defines the mirror.

[0063] Controlling the shape and optical surface conditions of the optical fiber ensures that the light flux is guided between the optical fiber and the optoelectronic component. Laser photopolymerization of transparent materials onto the optical fiber is simple and well-controlled. Once the material is printed and stabilized, the outer surface of the concave portion of the printed optical lens is fully or partially reflective by limiting the mirror to a given wavelength or wavelength range.

[0064] Therefore, compared with the prior art lens fibers, the advantages of the present invention are many, among which can be mentioned:

[0065] - Compared to the application of plane mirrors in the prior art, the use of a mirror on the concave part of the lens leads to a reduction in signal losses and thus an improvement in the balance of signal transmission;

[0066] -The reduction in signal loss is due to the light beam being focused as close as possible to the optical fiber or optoelectronic component by the concave mirror, which also improves the balance of signal transmission;

[0067] - Since the fiber is cut at 90° to the axis, also known as straight cleavage, the lens positioning accuracy is high;

[0068] - The light flux towards the optoelectronic component remains in the transparent material of the lens and does not pass through the optical fiber again, which simplifies the calculation of the light flux path;

[0069] -Lens shape is highly controlled using additive manufacturing technology through direct laser polymerization at the end of a pre-prepared optical fiber;

[0070] - By cutting the fiber at 90° to define a circular reference (fiber core diameter), the mirror is easier to position and manufacture relative to the fiber axis;

[0071] - Facilitates positioning of optical fibers in printing for additive manufacturing of lenses by cleaving them at 90°;

[0072] - It is easier to focus on 90° cleaved optical fiber;

[0073] - adding material for forming the lens not around the fiber but only at the end, enabling its installation in the V-groove;

[0074] - a single optical fiber with an optical lens that does not extend beyond the fiber cross section, which can be slid into the V-shaped groove of the support to manufacture an optical sub-assembly (OSA);

[0075] In the form of a multi-fiber optical subassembly (OSA) in a ribbon format, the angular positioning of the flat optical fibers is facilitated by the flat surface of the planar portion of the outer surface of the optical lens, on the one hand, and by the alignment axes of the different optical fibers of the ribbon, on the other hand. In the latter regard, the plane passing through the optical axes of all the optical fibers enables the fabrication of oriented straight prisms as part of the outer surface of the lens.

[0076] - Direct / in-situ additive manufacturing of fiber lenses enables the elimination of additional steps of assembly and gluing of separately manufactured optical components (e.g. by molding or replicating models);

[0077] - Possibility to print different lens shapes and sizes for each fiber in the fiber optic network;

[0078] - the possibility to adapt the lens to the specific situation, for example taking into account the incoming or outgoing light flux, or for different wavelengths;

[0079] - a single desired positioning of the optical lens on the optical fiber, thereby optimizing its position relative to the fiber core;

[0080] -Since unit manufacturing can be performed by two-photon (2PP) 3D printing, the lens shape can be flexibly changed, the cost is lower than the molding process, and various lens shapes can be quickly tested and the focus adjusted. Other advantages and features of the present invention will become more apparent by reading the detailed description of the embodiments of the present invention provided below as non-limiting examples with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] [ Figure 1 ] Figure 1 A longitudinal cross-sectional view showing an example of the lens fiber according to the present invention is shown.

[0082] [ Figure 2 ] Figure 2 yes Figure 1 A perspective view of a lensed fiber.

[0083] [ Figure 3 ] Figure 3 are perspective views of examples of lens fibers according to alternative and modified embodiments of optical lenses of the present invention.

[0084] [ Figure 4 ] Figure 4 Including according to Figure 1 and 2 Longitudinal cross-sectional view of an optical subassembly of a lensed optical fiber and optoelectronic components on its substrate.

[0085] [ Figure 5 ] Figure 5 is based on Figure 4 A perspective view of the optical subassembly.

[0086] [ Figure 6 ] Figure 6 is a perspective view of an example of a lens fiber according to a modified embodiment of the optical lens of the present invention.

[0087] [ Figure 7 ] Figure 7 is a perspective view showing an example of a multi-channel optical subassembly including a plurality of lensed optical fibers of the present invention and an optoelectronic module non-slip flange on a suitable support.

[0088] [ Figure 8 ] Figure 8is a perspective view of an optical lens pattern at the end of an optical fiber comprising two projecting protrusions forming axial positioning stops according to a first variant embodiment of the invention.

[0089] [ Figure 9 ] Figure 9 is a perspective view showing a second variant of embodiment of the optical lens having two projecting protrusions forming axial positioning stops.

[0090] [ Figure 10 ] Figure 10 is a perspective view showing a third variant of the embodiment of the optical lens having two protruding projections forming an axial positioning stop.

[0091] [ Figure 11 ] Figure 11 Is a vertical perspective view, which shows the Figure 9 A second variant is described, an axial stop for a single lens fiber with integrated protrusions.

[0092] [ Figure 12 ] Figure 12 Show again Figure 11 , but only a longitudinal cross-sectional view. DETAILED DESCRIPTION

[0093] In the following description and throughout this application, the terms "distal end" and "proximal end" are used with reference to the light flux passing through the lensed optical fiber according to the present invention. Thus, the distal end is the end of the optical fiber that includes the optical lens having the mirror of the present invention through which the light flux that has passed through the optical fiber is output.

[0094] Figure 1 and 2 An example of a lens fiber according to the present invention is shown, generally indicated by the reference numeral 1.

[0095] The lens fiber 1 first comprises an optical fiber 2 having a longitudinal axis (X), the optical fiber 2 including a core 20 and a jacket 21 surrounding the core 20 .

[0096] The distal end 22 of the optical fiber 2 is perpendicular to the plane of the longitudinal axis X.

[0097] A primary optical lens 3 having a single refractive index is provided at the distal end 22 of the optical fiber. Preferably, the optical lens is integrally formed with the optical fiber, ie fused together, and thus forms a single element together with the optical fiber.

[0098] The outer surface of the main lens 3 is defined by a concave portion 30 and a planar portion 31 which is parallel to the longitudinal axis X or inclined at a non-zero angle relative to the longitudinal axis X. This angle may be several tens of degrees.

[0099] Preferably, the concave portion 30 is a double cone, advantageously a double parabola.

[0100] This flat portion 31 is the surface of a right parallelepiped, the other side 32 of which is the free end of the lens having a non-zero height e. Preferably, this height e is at least 100 nm. For reasons of robustness of surface 32, the height is preferably at least 20 microns, even more preferably at least 50 microns. This minimum height e makes it possible to avoid having a fragile tip that is easily broken during handling of the lens fiber, for example when it is placed in support 9.

[0101] This flat portion 31 can serve as a mechanical support relative to surrounding elements or as a reference surface for defining an angular orientation relative to the longitudinal axis X of the optical fiber. In other words, the flat portion 31 enables the concave portion to be angularly oriented by rotation about the axis X of the optical fiber, and therefore enables the light flux leaving the lens to be oriented relative to said axis X.

[0102] Furthermore, the outer surface of the optical lens 3 is also defined by a circular portion 33 in a plane perpendicular to the axis X, conforming at least partially to the outer diameter of the optical fiber 2 .

[0103] The thickness e' of the end of the circular portion 33 of the prism ensures adhesion between the lens and the distal end 22 of the optical fiber during its manufacture. The thickness e' is preferably at least 100 nm. Within the range of optical fibers arranged in the optical fiber ribbon, the thickness e' may adopt different values ​​depending on the optical fiber in question, in order to compensate for any length differences between the optical fibers of the optical fiber ribbon resulting from the splitting operation.

[0104] Finally, another rounded portion 34 ensures the junction between the concave portion 30 and the right parallelepiped.

[0105] Advantageously, the height H of the lens 3, defined by the distance between the optical axis of the optical fiber and the top end of the circular portion 33, is less than or equal to the outer radius of the optical fiber. In other words, the circular portion 33 is preferably retracted into the cylindrical envelope of the optical fiber 2. The recessed positioning of the circular portion 33 relative to the cylindrical envelope of the optical fiber makes it easier to assemble the lens fiber in the support 9, in particular by sliding it in the groove 90.

[0106] The material of the main lens 3 is preferably transparent in a given wavelength range, preferably between 800 and 1700 nm.

[0107] The material of the lens 3 is preferably a photopolymer resin, such as epoxy resin, acrylate, urethane, or sol-gel material.

[0108] The mirror 4 is in contact with at least a portion of the concave portion 30 of the main lens 3 .

[0109] The mirror 4 is at least partially reflecting in at least one given wavelength range.

[0110] The mirror 4 can be a metal layer, preferably selected from the chemical elements Au, Al, Ni, Ag, or a dielectric layer reflecting in a given wavelength range, deposited on the concave portion 30 of the lens. The metal layer makes it possible to reflect all or part of the light flux. The dielectric layer makes it possible to reflect certain wavelengths, thus realizing a filter for each wavelength.

[0111] The operation of the lens fiber is as follows.

[0112] like Figure 1 As shown by the dashed lines in FIG, at least a portion of the light beam F from the core 20 of the optical fiber 2 diverges after passing through the distal end 22, passes through the lens 2, and is then reflected by the mirror 4, which focuses the light beam and thus exits perpendicularly to the longitudinal axis X, in particular through the flat portion 31 of the lens. The manufacture of the mirrored lens as close as possible to the distal end 22 of the optical fiber minimizes the dispersion of the light beam before it is incident on the concave mirror. This also makes it possible to reduce the size of the lens.

[0113] Conversely, at least a portion of the light beam that passes through the flat portion 31 of the lens is reflected by the mirror 4 and thereby exits through the core 20 of the optical fiber.

[0114] The flat portion 31 of the outer surface of the main lens 3 makes it possible to avoid introducing any additional deformation into the light beam F entering or leaving through this surface.

[0115] Figure 3 An alternative embodiment of the invention shown in can consist in implementing a planar portion that is non-parallel to the longitudinal axis X, i.e., tilted at a non-zero angle relative to this axis. Thus, in the case of a light beam originating from an optical fiber and reflected by a mirror at an angle different from 90°, the light beam reflected by the mirror can be made to pass perpendicularly through a planar portion 31 that is non-parallel to the longitudinal axis X of the optical fiber, without introducing any new deviations in the trajectory of the light beam. Furthermore, a planar portion 31 tilted at a non-zero angle relative to the axis of the optical fiber makes it possible to prevent the light emitted by the light source from being reflected back toward itself.

[0116] Furthermore, compared to conventional lensed fibers comprising a flat mirror and a separate lens, the reflective concave surface of the present invention achieves twice the convergence rate for the same lens radius. In other words, a light beam can be focused onto the surface of an optical fiber or optoelectronic component at a very short distance. Thus, the reflective concave surface of the present invention enables the creation of an optical system that redirects and converges light beams more compactly.

[0117] An advantageous variant may realize an additional optical lens 5, also with a single refractive index, in addition to the main lens 3, below the planar portion 31. According to this variant, the planar portion 31 may be parallel or non-parallel to the longitudinal axis X of the optical fiber.

[0118] therefore, Figure 3A configuration is shown with the additional optical lens 5 tilted relative to the longitudinal axis X below the flat portion 31 .

[0119] Preferably, the outer surface of the additional lens 5 may be a biconical surface, more preferably a biparaboloid surface.

[0120] The material of the additional lens 5 is preferably transparent in a given wavelength range, preferably between 800 and 1700 nm.

[0121] The material of the lens 5 is preferably a photopolymer resin, such as epoxy resin, acrylate, urethane, or sol-gel material.

[0122] This additional optical lens 5 also makes it possible to improve the focusing of the light beam coming from the optical fiber towards the optoelectronic component, and vice versa.This additional lens 5 is preferably formed as a single-piece element with the optical fiber 2 and the main lens 3.

[0123] Therefore, in order to realize the complex shape of the main lens 3, with additional optical lenses 5 if appropriate and in the most appropriate dimensions, the inventors use the additive printing technique of photopolymerization (preferably with laser). This method enables the realization of a compact lens directly at the end of a single optical fiber.

[0124] More specifically, to implement the lens fiber 1 described above, the following steps are performed:

[0125] i / Positioning the optical fiber 2 on the support,

[0126] ii / cutting at 90°, in particular by cleaving, and preparing the distal end 22 of the optical fiber,

[0127] iii / dipping or immersing the distal end 22 of the optical fiber in a resin of a photopolymer material,

[0128] iv / polymerizing a resin by laser to form an outer surface of the optical lens, the outer surface being defined by at least a concave portion 30 and a flat portion 31 parallel to the longitudinal axis X of the optical fiber or inclined at a non-zero angle relative to the longitudinal axis X of the optical fiber, and in particular with the optical lens 5 below the flat portion 31,

[0129] v / Depositing an at least partially reflective material on all or part of the concave portion of the outer surface of the lens in order to form a reflector 4.

[0130] Step ii / may be performed before step i / .

[0131] Figure 4 and 5 An optical sub-assembly (OSA) 6 is shown with the lensed fiber 1 integrated therein.

[0132] The subassembly 6 includes an optoelectronic component 7 that is spaced apart from and faces the planar portion 31 of the primary lens 3. The optoelectronic component 7 can be a light source, in particular a VCSEL laser, or a light receiver, in particular a photodiode. The distance between the planar portion 31 and the surface of the optoelectronic component can vary from a few micrometers to several hundred micrometers.

[0133] As shown in the figure, the optoelectronic assembly 7 can be supported by a substrate 70, and the space between the optoelectronic assembly 7 and the flat portion 31 of the main lens 3 (or, if necessary, the additional lens 5) is filled with air or a resin that is transparent in a given wavelength range. The resin, in particular, different from the resin used to form the reflector lens, can protect the lens fiber, in particular the optical surfaces of the flat portion 31 and / or the additional optical lens 5, and / or the optical surfaces of the optoelectronic assembly from mechanical (scratches, etc.), chemical or environmental (humidity, fluids, etc.) contamination or corrosion.

[0134] like Figure 4 As shown, the light beam F entering or exiting through the flat portion 31 of the main lens 3 is completely focused on the optoelectronic component 7 .

[0135] Figure 6 An alternative form of an optimized lens 3 is shown. The right parallelepiped is replaced by a tapered, rounded side profile 35 below the concave portion 30. The shape of this outer surface is optimized, and the rounded side profile 35 reduces the volume of resin to be polymerized to obtain the lens 3, which saves time while maintaining a strong shape. The rounded side profile 35 also avoids fragile edges at the base of the right parallelepiped.

[0136] Figure 7 An optical subassembly 8 is shown which is a so-called multi-channel optical element, i.e. comprising a plurality of lensed optical fibers 1 forming a ribbon. Each channel can be a signal transmitter and / or a signal receiver.

[0137] In this subassembly 8, a plurality of lens fibers 1.1, 2.1, 1.3, and 1.4 are each positioned and locked in one of the grooves 90 of the support 9, which is preferably V-shaped. A rounded portion 33, which at least partially conforms to the outer diameter of the optical fiber 2 or advantageously retracts within the cylindrical envelope of the optical fiber 2, allows the lens fiber to be positioned in one of the grooves without interference between it and the lens. This enables the distance between the grooves, and therefore the distance between the lens fibers, to be adjusted to the smallest possible size. This enables an OSA with the most compact dimensions possible.

[0138] In the case of optical fibers arranged in the form of a ribbon, the combination of the longitudinal axes X of the optical fibers can define a common plane P. When a lens is manufactured on each optical fiber, the common plane P, associated with the planar portion 31 of the lens to be manufactured, makes it possible to easily define the angular orientation of each lens relative to the axis X of its associated optical fiber. Thus, each lens manufactured on each optical fiber of the ribbon is correctly oriented relative to the plane P and the longitudinal axis X, and subsequently relative to the support 9 receiving the lensed optical fiber in its groove 90.

[0139] The anti-slip flanges 10 of the plurality of optoelectronic assemblies are arranged on the support, with each optoelectronic assembly spaced a distance from and positioned opposite the flat portion 31 of the lens of one of the optical fibers 1.1, 2, 1.3, and 1.4. The anti-slip flanges 10 may or may not be directly arranged on the support. For example, they may be mounted on an intermediate assembly that faces the support 9.

[0140] Figure 4 and 5 or Figure 7 The optical subassembly OSA shown in FIG. 1 can be integrated into an optoelectronic module.

[0141] Figure 8 A mode of the optical lens 3 at the end of the optical fiber is shown, which comprises two protrusions 36 arranged on both sides of the reflector 4, the protrusions forming stops for axial positioning.

[0142] As shown, two protrusions 36 extend from the planar portion 31 where the light beam exits, with a portion being on the curved outer surface 33 and extending beyond the plane 32 of the lens.

[0143] As shown, each protrusion 36 includes a stop surface 360 ​​that is perpendicular to the longitudinal axis (X) of the optical fiber.

[0144] Figure 9 An alternative is shown according to which the projections of the two protrusions 37 extend only from the curved outer surface 33 and therefore not from the planar portion 31 .

[0145] Here, each protrusion 37 comprises a stop plane 370 perpendicular to the longitudinal axis (X) of the optical fiber.

[0146] Figure 10 Another alternative is shown, according to which the projections of both protrusions 38 have a trumpet shape extending from the free end 32 of the optical lens.

[0147] Here, too, each protrusion 38 comprises a stop plane 380 perpendicular to the longitudinal axis (X) of the optical fiber.

[0148] Advantageously, the material of the stop is the same as the material of the optical lens.

[0149] Figure 11 and Figure 12 The axial stop of a single lens fiber 1 passing through a protrusion 37 is illustrated, with the planar end face 370 of the protrusion 37 pressing against an adapter element, which may be, for example, the area of ​​a non-slip flange 10 of a plurality of optoelectronic components 7. The stop element may also be a support 9, for example a vertical surface of a silicon or glass substrate.

[0150] Thus, the single lens fiber 1 is inserted by sliding into the, for example, V-shaped groove 90 of the support 9 until the axial mechanical stop of the face 370 perpendicularly against the element is detected.

[0151] Due to these axial mechanical stops, the mirror 4 is perfectly positioned relative to the optoelectronic component 7 and the light beam at the output of the planar portion 31 is therefore perfectly focused on said component 7 .

[0152] Region 360,370 or 380 is not necessarily planar, and if surface 360,370 or 380 is cylindrical, the abutment towards the appropriate element can be linear type. Without departing from the scope of the invention, the abutment can also be point-shaped, depending on the contact form selected.

[0153] Other variations and modifications may be devised without departing from the scope of the invention.

[0154] The shape and / or size of the optical lenses may differ from those shown and may have any shape with a concave outer surface. They may, for example, be partially in the form of a right parallelepiped or another ... preferably such that the circular portion 33 of the lens is recessed within the cylindrical envelope of the optical fiber.

Claims

1. A single lens optical fiber (1), comprising An optical fiber (2) having a longitudinal axis (X), wherein the distal end (22) of the optical fiber is a plane perpendicular to the longitudinal axis; A primary optical lens (3) having a single refractive index is arranged at the distal end of the optical fiber, and its outer surface is defined by at least a concave portion (30) and a planar portion (31) parallel to the longitudinal axis of the optical fiber or inclined at a non-zero angle to the longitudinal axis of the optical fiber, the optical lens being integrally formed on the distal end of the optical fiber, forming an integral component with the distal end of the optical fiber; A mirror (4) is matched with at least a portion of the concave portion of the main lens, and the mirror is at least partially reflective in at least one given wavelength range, so that at least a portion of the light beam (F) coming from the optical fiber and passing through the main lens is reflected by the mirror to be emitted through the flat portion (31) of the main lens, or conversely, at least a portion of the light beam passing through the flat portion of the main lens and passing through the main lens is reflected by the mirror to be emitted through the optical fiber.

2. The lens fiber according to claim 1, wherein the primary optical lens is fused with the optical fiber to form an integral component.

3. The lens fiber according to claim 1 or 2, comprising an additional optical lens (5) arranged on the surface of the flat portion (31).

4. Lensed fiber according to any of the preceding claims, the height (H) of the primary lens being less than or equal to the outer radius of the fiber.

5. Lens fiber according to one of the preceding claims, the concave portion of the outer surface of the main lens and, if necessary, of the additional lens being a biconical surface, preferably a biparaboloid.

6. Lensed fiber according to one of the preceding claims, the material of the main lens and, if necessary, of the additional lens being transparent in a given wavelength range, preferably between 800 and 1700 nm.

7. Lensed fiber according to one of the preceding claims, the mirror being a metal layer deposited on the concave part of the main lens, the metal preferably being selected from Au, Al, Ni and Ag.

8. The lens fiber according to any one of claims 1 to 7, wherein the mirror is a dielectric layer reflecting within a given wavelength range.

9. The lens fiber according to one of the preceding claims, comprising at least one protrusion, preferably two protrusions arranged on either side of the mirror (4), projecting beyond the free end (32) of the outer surface, the protrusion being used to form an axial stop with the support (10) for axial positioning of the optical fiber.

10. The lens fiber according to claim 9, each protrusion comprising a region of stop perpendicular to the longitudinal axis (X) of the fiber, the region preferably being of planar shape.

11. The lens fiber according to claim 9 or 10, wherein the protrusion is realized by transverse circumcision in the cross section of the lens fiber.

12. An optical subassembly (6) comprising: at least one lens fiber (1) according to one of the preceding claims, At least one optoelectronic component (7) is arranged facing a planar portion of the main lens and at a distance therefrom, the planar portion being parallel to the longitudinal axis (X) of the optical fiber or tilted at a non-zero angle to the longitudinal axis (X) of the optical fiber.

13. The optical subassembly according to claim 12, wherein the space between the optoelectronic component and the flat portion of the main lens or, if necessary, the additional lens is filled with air, a resin transparent in a given wavelength range, or an adhesive transparent in a given wavelength range.

14. An optical subassembly according to claim 12 or 13, comprising: The support member (9) comprises a plurality of grooves (90), which are preferably V-shaped. A plurality of lens fibers (1.1, 1.2, 1.3, ...) are each positioned and locked in one of the grooves, A plurality of anti-slip flanges (10) of optoelectronic components are arranged on a support, each of the optoelectronic components facing and spaced apart from a plane portion of a main lens of one of the optical fibers.

15. A method for preparing a single lens optical fiber according to any one of claims 1 to 11, comprising the following steps: i / Positioning the optical fiber on the support, ii / cutting at 90°, in particular by cleaving, and preparing the distal end of the optical fiber, iii / dipping or immersing the distal end of the optical fiber in a resin of a photopolymer material, iv / forming an outer surface of a primary optical lens by laser polymerizing a resin, the outer surface being defined by at least a concave portion and a planar portion parallel to the longitudinal axis of the optical fiber or inclined at a non-zero angle to the longitudinal axis of the optical fiber, v / Depositing an at least partially reflective material on all or part of the concave portion of the outer surface of the main lens in order to form the mirror.

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