Lensed optical fiber comprising an optical fiber at the distal end cleaved at 90° and fused with a lens on the external surface of which a concave mirror is formed.

Abstract

Lensed optical fiber comprising an optical fiber at the distal end cleaved at 90° and fused with a lens on the external surface of which a concave mirror is formed. The invention essentially consists of a lensed optical fiber (1) comprising an optical lens (3), preferably fused at the end of an optical fiber (2) cut at a right angle and whose shape, in particular of its external surface (4) which is perfectly controlled makes it possible to produce a catadioptric optic or concave mirror with an angle return to adapt and optimize the optical flows entering or leaving between an optical fiber and an optoelectronic component, in transmission or reception. Figure for the abstract: Fig.1

Description

Title of the invention: Lensed optical fiber comprising an optical fiber at the distal end cleaved at 90° and fused with a lens on the external surface of which a concave mirror is formed. Technical field

[0001] The present invention relates to the field of optical fibers, more particularly lensed optical fibers, intended for optical and / or data transmission.

[0002] A lensed optical fiber is an optical fiber one of whose ends, called the distal end, is extended by an optical element adapted to reform an optical flow entering or leaving the fiber.

[0003] The invention also relates to an optical subassembly or OSA (“Optical Sub Assembly”) which is a subassembly grouping together one or more optoelectronic components and one or more lensed optical fibers.

[0004] The invention relates to both a transmitter subassembly, intended to convert an electrical signal into an optical signal, and a receiver subassembly intended to convert an optical signal into an electrical signal.

[0005] The invention also relates to an optoelectronic module which integrates one or more sub-assemblies, on an electronic card in a housing.

[0006] The invention also relates to a transmitter-receiver module which combines a receiver subassembly and a transmitter subassembly which share common electronic circuits and a common electronic card, usually referred to in English as "Transceiver", a contraction of "TRANSmitter" ("transmitter") and "reCEIVER" ("receiver").

[0007] A preferred application of the invention concerns optoelectronic modules intended to be implemented in particular in the aeronautical field, the space field, the defense field, the transport or medical field or even the telecommunications field, the data communications field and the industrial field.

[0008] Although described with reference to this preferred application, the invention can be applied to any system requiring the installation of a lensed optical fiber. Prior art

[0009] Optical connection systems are known which use optoelectronic modules and an optical link made by one or more optical fibers. Each optoelectronic transmitter or receiver module consists of an electronic card, an optoelectronic component and its electronic control component, one or more optical fibers which can be concatenated into ribbons and an optical coupling device between the optoelectronic component(s) and the optical fiber(s).

[0010] As an optical coupling device, it is known to implement a lensed optical fiber to adapt the optical flows between said optical fiber and an optoelectronic component. In transmission, the optical flow is thus optimized between an optical or light source, such as an LED (an English acronym for "Eight-Emitting Diode"), a laser, a VCSEL laser (an English acronym for "Vertical-Cavity Surface-Emitting Easer"), and the optical fiber (waveguide) which carries the optical flow to transmit an optical signal. In reception, the optical flow is optimized between the optical fiber and the light receiver (photodiode, etc.).

[0011] Patent EP1481274B1 discloses in one embodiment an optical fiber, called “pigtail”, corresponding to the Anglo-Saxon term “pigtail”, that is to say not connectorized at one of its ends, called proximal, and whose distal end is fused with several adjoining optical elements including two spacers in the form of portions of optical fiber without core and with a single refractive index, arranged on either side of a gradient refractive index (GRIN) optical lens, ending with a bevel coated with a reflective aspherical surface which forms the free end. Alternatively, instead of the bevel and the reflective aspherical surface, a curved surface is provided at the end of the distal spacer, so that an optical signal directed against this curved surface is redirected.Whatever the method, this solution is complex and expensive to manufacture and furthermore does not allow to concentrate an optical beam coming directly out of the “pigtail” optical fiber. Indeed, whatever the embodiment presented in this patent, the optical fiber is always equipped, at its distal end, with at least one GRIN lens allowing to collimate the optical beam before arriving on the mirror, plane or concave. Also, the removal of such a GRIN lens would cause a lack of convergence or parallelization of the optical beam, leading to a loss of optical flow, at the optical fiber input or at the optoelectronic component.

[0012] Patent application US2021 / 341688 discloses an optical coupling system between optical fibers and a VCSEL laser, which comprises an optical ferrule comprising a body beveled at an angle of approximately 45° at its distal end and optical fibers flush with the beveled surface of the body, and a concave mirror made at the end of some of the fibers. This solution is also complex and expensive to manufacture. In addition, a 45° bevel involves an additional difficulty in positioning the optical axis at the fiber outlet on the beveled surface, because the intersection between the beveled surface of the fiber end and the cylinder constituting the envelope of the core of the optical fiber forms an ellipse. This consequently leads to imperfect precision in the positioning of the concave mirror relative to the optical axis of the fiber. Furthermore, the complexity of positioning the lens relative to the optical axis can lead to longer, and therefore more expensive, manufacturing adjustments. Finally, the optical flow to or from the VCSEL laser passes through at least one material of one of the optical fibers, in particular the cladding of the optical fiber, which complicates the calculation of the optical flow path. In addition, this solution does not allow obtaining a flat reference surface for the angular orientation of the lens around the axis of the optical fiber.

[0013] There is therefore a need to improve lensed optical fibers, in particular intended to achieve optical coupling with an optoelectronic component, in order to overcome the aforementioned drawbacks.

[0014] The invention aims to meet all or part of this need. Statement of the invention

[0015] To this end, the invention relates, according to one of its aspects, to a lensed optical fiber comprising:

[0016] - an optical fiber with a longitudinal axis (X), the distal end of which is a surface plane orthogonal to the longitudinal axis; :

[0017] - a main optical lens with a single refractive index, arranged at the end distal to the fiber and whose external surface is delimited at least by a concave portion and a flat portion, parallel to or inclined at a non-zero angle with the longitudinal axis of the fiber;

[0018] - a mirror matching at least part of the concave portion of the lens main lens, the mirror being at least partly reflective in at least one given wavelength range, such that at least part of an optical beam coming from the fiber and passing through the main lens is reflected by the mirror to exit through the plane portion of the main lens or vice versa, that at least part of an optical beam passing through the plane portion of the main lens and passing through the main lens is reflected by the mirror to exit through the fiber.

[0019] By “concave” is meant here and within the scope of the invention, a surface whose hollow is oriented towards the optical fiber.

[0020] Advantageously, the main optical lens is fused with the optical fiber so as to form a single-piece element.

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

[0022] According to an advantageous configuration, the external surface of the main optical lens is also delimited by a free end portion of height (e) greater than or equal to 100 nm.

[0023] According to this configuration and an advantageous characteristic, the external surface of the main optical lens is delimited by a right parallelepiped of which one face is the flat portion and another face is the free end portion of non-zero height.

[0024] According to another advantageous configuration, the external surface of the main optical lens is also delimited by a rounded portion matching at least in part the external diameter of the optical fiber.

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

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

[0027] Advantageously also, the concave portion of the external surface of the main lens, and where appropriate of the additional one, is a biconical surface, preferably a double-paraboloid.

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

[0029] The material constituting the main lens, and where appropriate the additional lens, may be chosen from transparent polymers or a glass transparent at the wavelength used, preferably between 800 and 1700 nm. It may be a photopolymer resin, such as an epoxy, an acrylate or a combination thereof, an unsaturated polyester, a urethane, a sol-gel material. It may also be a thermoplastic resin, such as polyethyleneimine (PEI) or polyamide-imide (PAI).

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

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

[0032] The invention also relates to an optical subassembly comprising:

[0033] - at least one lensed optical fiber as described previously,

[0034] - at least one optoelectronic component, arranged at a distance from and facing the flat portion of the main lens parallel to or inclined at a non-zero angle with the longitudinal axis of the fiber.

[0035] Preferably, the space between the optoelectronic component and the flat portion of the main lens, or where appropriate with the additional lens, is filled with air, of transparent resin in the given wavelength range or of a transparent adhesive in the given wavelength range.

[0036] According to a multi-way embodiment, the subassembly comprises:

[0037] - a support comprising a plurality of grooves, preferably V-shaped,

[0038] - a plurality of lensed optical fibers each positioned and locked in a grooves,

[0039] - a strip of a plurality of optoelectronic components, arranged on the support with each of the optoelectronic components, arranged at a distance and opposite the flat portion of the main lens of one of the optical fibers.

[0040] The invention also relates to an optoelectronic module, comprising at least one optical subassembly as described previously.

[0041] The invention finally relates to a method for producing a lensed optical fiber as described above, comprising the following steps:

[0042] i / positioning of an optical fiber on a support,

[0043] ii / cutting at 90°, in particular by cleaving, and preparation of the distal end of the optical fiber,

[0044] iii / dipping or immersing the distal end of the optical fiber in a resin made of photopolymer material,

[0045] iv / laser polymerization of the resin in order to form an external surface of the main optical lens delimited at least by a concave portion and a flat portion, parallel to the longitudinal axis of the optical fiber,

[0046] v / depositing an at least partially reflective material on all or part of the concave portion of the external surface of the main lens, so as to form the mirror.

[0047] Step i / can be carried out before step ii / or conversely step ii / can be carried out before step i / .

[0048] By "preparation" is meant here and within the scope of the invention, all the usual surfacing steps to ensure a desired state of the optical fiber end surface, in particular with high flatness and low roughness, for example by cleaving and / or polishing.

[0049] By "dipping" is meant here and within the scope of the invention, the fact of immersing the end of an optical fiber in a bath of photopolymer resin then its removal from the bath before the start of polymerization, in the drop remaining by capillarity at the end of the fiber.

[0050] By "immersion" is meant here and within the scope of the invention, the fact of immersing the end of an optical fiber in a bath of photopolymer resin and leaving it in the bath during polymerization.

[0051] Step iv / is advantageously carried out by two-photon photopolymerization (from the English acronym “2PP” for “two photon polymerization”).

[0052] Thus, the invention essentially consists of a lensed optical fiber, with an optical lens, preferably fused at the end of an optical fiber cut at a right angle and whose shape, in particular of its external surface which is perfectly controlled, makes it possible to produce a catadioptric optic or concave mirror with an angle return to adapt and optimize the optical flows entering or leaving between an optical fiber and an optoelectronic component, in transmission or in reception.

[0053] The optical lens is preferably directly added / fused to the distal end of the optical fiber, i.e. forming a single-piece element with the latter, by deformation of the optical fiber itself, advantageously by additive or 3D printing by photopolymerization, preferably by laser, on the optical fiber of a material transparent to the wavelengths used, before reflective treatment to obtain the catadioptric surface delimiting the mirror.

[0054] Controlling the shape of an optical fiber and the surface condition of the optics makes it possible to guarantee the guidance of the optical flow between the fiber and the optoelectronic component. Printing by laser polymerization of a transparent material directly onto the fiber is simple and well controlled. Once the material is printed and stabilized, the external surface of the concave portion of the printed optical lens is made totally or partially reflective by defining a mirror for a given wavelength or wavelength range.

[0055] Thus, the advantages of the invention compared to lensed optical fibers according to the state of the art are numerous, among which we can cite: - a reduction in signal losses due to the implementation of a mirror on the concave portion of the lens, compared to the implementation of a plane mirror according to the prior art, and thereby an improvement in the signal transmission balance; - a reduction in signal losses due to the focusing of the optical beam by the concave mirror, as close as possible to the optical fiber or the optoelectronic component, and thereby an improvement in the signal transmission balance; - high precision in the positioning of the lens due to the cutting, also called straight cleavage, at 90° to the axis of the fiber; - the optical flow towards the optoelectronic component remains in the transparent material of the lens and does not pass back through the optical fiber, which simplifies the calculation of the optical flow path; - great control of the lens shape using the additive manufacturing technique by laser polymerization directly at the end of a previously prepared optical fiber; - easier positioning and manufacturing of the mirror relative to the fiber axis made possible by cutting the fiber at 90° which defines a circular reference frame (diameter of the fiber core); - positioning of the optical fiber in an additive manufacturing printer for the lens, facilitated by cutting the fiber at 90°; - easier focusing of the focal length at the interface on an optical fiber cleaved at 90°; - in a multi-fiber optical subassembly (OSA) version in the form of a ribbon, an angular positioning of the fibers flat facilitated on the one hand by the flat surface of the flat portion of the external surface of the optical lens and on the other by the alignment axis of the different optical fibers of the ribbon. On this last point, the plane passing through the optical axes of all the fibers makes it possible to orient the production of a right prism as part of the external surface of the lens. - direct / in situ additive manufacturing of the lens on optical fiber eliminates the need for an additional assembly step, gluing a separately manufactured optic, for example by molding

[0056] Other advantages and characteristics of the invention will become more apparent upon reading the detailed description of examples of implementation of the invention given by way of illustration and not limitation with reference to the following figures. Brief description of the drawings

[0057] [Fig-1] [Fig. 1] represents in longitudinal sectional view an example of a lensed optical fiber according to the invention.

[0058] [Fig.2] [Fig.2] is a perspective view of the lensed optical fiber according to the [Fig.l].

[0059] [Fig.3] [Fig.3] is a perspective view of an example of a lensed optical fiber according to an alternative and a variant embodiment of the optical lens according to the invention.

[0060] [Fig.4] [Fig.4] represents in longitudinal section a subassembly optics comprising a lensed optical fiber according to figures 1 and 2 and an optoelectronic component on its substrate.

[0061] [Fig.5] [Fig.5] is a perspective view of the optical subassembly according to [Fig.4],

[0062] [Fig.6] [Fig.6] is a perspective view of an example of a lensed optical fiber according to an alternative embodiment of the optical lens according to the invention.

[0063] [Fig.7] [Fig.7] is a perspective view showing an example of a subassembly multi-channel optics comprising a plurality of lensed optical fibers according to the invention and a strip of optoelectronic components on a suitable support. Detailed description

[0064] In the following description and throughout the present application, the terms "distal" and "proximal" are used by reference to an optical flow through a lensed optical fiber according to the invention. Thus, the distal end is the end of the fiber comprising the optical lens with mirror of the invention through which an optical flow having traveled through the optical fiber exits.

[0065] Figures 1 and 2 show an example of a lensed optical fiber according to the invention, generally designated by the reference 1.

[0066] This lensed fiber 1 firstly comprises an optical fiber 2 with a longitudinal axis (X) comprising a core 20 and a cladding 21 surrounding the core 20.

[0067] The distal end 22 of the fiber 2 is a flat surface orthogonal to the longitudinal axis X.

[0068] A main optical lens 3 with a single refractive index is arranged at the distal end 22 of the fiber. Preferably, the optical lens is formed integrally, i.e. fused, with the fiber and therefore forms a single-piece element with the latter.

[0069] The external surface of this main lens 3 is delimited by a concave portion 30 and a flat portion 31, parallel to the longitudinal axis X or inclined at a non-zero angle relative to the longitudinal axis X. This angle can be a few tens of degrees.

[0070] Preferably, the concave portion 30 is a biconical surface, advantageously a double-paraboloid.

[0071] This flat portion 31 is a face of a right parallelepiped, another face 32 of which is the free end portion of the lens of non-zero height e. Preferably, this height e is at least equal to 100 nm. For reasons of robustness of the face 32, the height e is preferably at least 20 pm, or even preferably at least 50 pm. This minimum height e makes it possible to avoid having a fragile, therefore brittle, tip when handling the lensed fiber, for example when positioning it in a support 9.

[0072] This flat portion 31 can be used as a mechanical support with a surrounding element or as a reference surface to define an angular orientation relative to the longitudinal axis X of the optical fiber. In other words, the flat portion 31 makes it possible to orient the concave portion angularly in rotation around the X axis of the optical fiber, and therefore to orient the optical flow leaving the lens relative to said X axis.

[0073] Furthermore, the external surface of the optical lens 3 is also delimited by a rounded portion 33, in a plane perpendicular to the axis X, matching at least in part the external diameter of the optical fiber 2.

[0074] The thickness e' of the end of the rounded portion 33 of the prism ensures adhesion between the lens, during its manufacture, and the distal end 22 of the fiber. The thickness e' is preferably at least 100 nm. In the context of optical fibers arranged in a ribbon, the thickness e' may take a different value depending on the fiber considered, in order to compensate for possible differences in length between fibers of the ribbon following the cleaving operation.

[0075] Finally, another rounded portion 34 can provide the junction between the concave portion 30 and the straight parallelepiped.

[0076] Advantageously, the height H of the lens 3, defined by the distance between the optical axis of the fiber and the top of the rounded portion 33, is less than or equal to the external radius of the optical fiber. In other words, the rounded portion 33 is preferably set back inside the cylindrical envelope of the optical fiber 2. The set-back positioning of the rounded portion 33 relative to the cylindrical envelope of the optical fiber facilitates the assembly of the lensed optical fiber in the support 9, in particular the assembly by sliding in the grooves 90.

[0077] The material of the main lens 3 is preferably transparent in a given wavelength range, preferably between 800 and 1700 nm.

[0078] The material of the lens 3 is preferably a photopolymer resin, for example epoxy, acrylate, urethane, or a sol-gel material.

[0079] A mirror 4 matches at least part of the concave portion 30 of the main lens 3. This mirror 4 is at least partly reflective in at least the given wavelength range.

[0080] The mirror 4 may be a metallic layer, preferably chosen from the chemical elements Au, Al, Ni, Ag, or a reflective dielectric layer in the given wavelength range, deposited on the concave portion 30 of the lens. The metallic layer makes it possible to reflect all or part of the optical flux. The dielectric layer makes it possible to reflect certain wavelengths, thus producing a filter per wavelength.

[0081] The operation of the lensed optical fiber is as follows.

[0082] As illustrated by the dotted lines in [Fig.l], at least a portion of an optical beam F coming from the core 20 of the fiber 2 diverges after passing through the distal end 22, passing through the lens 2 and then being reflected by the mirror 4 which focuses, to exit, in particular perpendicular to the longitudinal axis X, by the flat portion 31 of the lens. The production of the mirror lens, as close as possible to the distal end 22 of the optical fiber limits as much as possible the dispersion of the beam before its incidence on the concave mirror. This also makes it possible to reduce the size of the lens.

[0083] Conversely, at least part of an optical beam passing through the flat portion 31 of the lens is reflected by the mirror 4 to exit through the core 20 of the fiber.

[0084] The flat portion 31 of the external surface of the main lens 3 makes it possible not to introduce any additional deformation on the optical beam F entering or exiting via this face.

[0085] An alternative of the invention illustrated in [Fig. 3] may consist in producing a planar portion not parallel to the longitudinal axis X, that is to say inclined at a non-zero angle relative to it. Thus, in the case of an optical beam coming from the optical fiber and reflected by the mirror at an angle other than 90°, a planar portion 31 not parallel to the longitudinal axis X of the optical fiber can be crossed perpendicularly by the beam reflected by the mirror, without introducing any new deviation in the trajectory of the beam. In addition, a planar portion 31 inclined at a non-zero angle relative to the axis of the fiber makes it possible to avoid reflection of the light emitted by a light source towards itself.

[0086] Furthermore, compared to the lensed fibers of the prior art comprising a plane mirror and a separate lens, the reflective concave portion of the invention is twice as convergent for the same lens radius. In other words, the optical beam can focus towards the optical fiber or towards the surface of the optoelectronic component over a much shorter distance. Consequently, the reflective concave portion according to the invention makes it possible to obtain an optical system redirecting and converging the optical beam that is much more compact.

[0087] An advantageous variant may consist of producing, below the flat portion 31, an additional optical lens 5, also with a single refractive index, in addition to the main lens 3. According to this variant, the flat portion 31 may or may not be parallel to the longitudinal axis X of the fiber.

[0088] [Fig.3] thus shows a configuration with the additional optical lens 5 below a flat portion 31 inclined relative to the longitudinal axis X.

[0089] Preferably, the external surface of this additional lens 5 may be biconical, more preferably a double paraboloid.

[0090] The material of the additional lens 5 is preferably transparent in a given wavelength range, preferably between 800 and 1700 nm.

[0091] The material of the lens 5 is preferably a photopolymer resin, for example epoxy, acrylate, urethane, or a sol-gel material.

[0092] This additional optical lens 5 further improves the focusing of a beam coming from the optical fiber towards an optoelectronic component, and vice versa. This additional lens 5 preferably forms a single-piece element with the fiber 2 and the main lens 3.

[0093] Thus, to produce this complex shape of main lens 3, where appropriate with the additional optical lens 5 and with the dimensions most suited to the needs, the inventors implemented an additive printing technique by photopolymerization, preferably by laser. This method makes it possible to produce a compact lens directly at the end of a unitary optical fiber.

[0094] More precisely, to produce a lensed optical fiber 1 which has just been described, the following steps are carried out:

[0095] i / positioning of an optical fiber 2 on a support,

[0096] ii / cutting at 90°, in particular by cleaving, and preparation of the distal end 22 of the optical fiber,

[0097] iii / dipping or immersing the distal end 22 of the optical fiber in a resin made of photopolymer material,

[0098] iv / laser polymerization of the resin in order to form an external optical lens surface delimited at least by a concave portion 30 and a flat portion 31, parallel or inclined at a non-zero angle relative to the longitudinal axis X of the optical fiber, and in particular with an additional optical lens 5 below the flat portion 31,

[0099] v / depositing an at least partially reflective material on all or part of the concave portion of the external surface of the lens, so as to form the mirror 4.

[0100] Step ii / can be carried out before step i / .

[0101] An optical subassembly (OSA) 6 integrating a lensed optical fiber 1 which has just been described is shown in Figures 4 and 5.

[0102] This subassembly 6 comprises an optoelectronic component 7 arranged at a distance from and facing the flat portion 31 of the main lens 3. The optoelectronic component 7 may be a light source, in particular a VCSEL laser, or a light receiver, in particular a photodiode. The distance between the flat portion 31 and the surface of the optoelectronic component may vary from a few microns to a few hundred microns.

[0103] As shown, the optoelectronic component 7 may be supported by a substrate 70 and the space between the optoelectronic component 7 and the planar portion 31 of the main lens 3, or where appropriate with the additional lens 5, is filled with air or transparent resin in the given wavelength range. The resin, in particular different from that used to produce the mirror lens, makes it possible to protect the optical surfaces of the lensed fiber, in particular the planar portion 31 and / or the lens additional optics 5, and / or the opto-electronic component from pollution or mechanical attacks (scratches, etc.), chemical or environmental (humidity, fluids, etc.).

[0104] As illustrated in [Fig.4], the optical beam F entering or exiting through the flat portion 31 of the main lens 3 is perfectly focused on the optoelectronic component 7.

[0105] [Fig.6] illustrates an optimized lens shape variant 3. The straight parallelepiped is replaced by a tapered, rounded lateral shape 35 below the concave portion 30. This optimized external surface shape with the lateral rounded portion 35 reduces the volume of resin to be polymerized to obtain the lens 3, which saves time, while maintaining a robust shape. This lateral rounded portion 35 also avoids fragile edges at the base of the straight parallelepiped.

[0106] [Fig.7] illustrates an optical subassembly 8 called multi-optical channel, i.e. comprising several lensed optical fibers 1 forming a ribbon. Each channel can be a transmitter and / or receiver of signals.

[0107] In this subassembly 8, a plurality of lensed optical fibers 1.1, 1.2, 1.3, 1.4 are each positioned and locked in one of the grooves 90, preferably V-shaped, of a support 9. The rounded portion 33 matching at least in part the external diameter of the optical fiber 2, or advantageously located set back inside the cylindrical envelope of the optical fiber 2, makes it possible to position the lensed fiber in one of the grooves without interference between the latter and the lens. Consequently, this makes it possible to adapt the pitch between the grooves, therefore between the lensed fibers, towards the smallest possible dimension. This makes it possible to obtain an OSA with the most compact dimensions possible.

[0108] In the context of optical fibers arranged in a ribbon, the set of longitudinal axes X of the optical fibers makes it possible to define a common plane P. When producing the lens on each fiber, the common plane P in association with the flat portion 31 of the lens to be produced 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 produced on each optical fiber of the ribbon is correctly oriented relative to the plane P and the longitudinal axis X, and then correctly oriented relative to the support 9 receiving the lensed fibers in the grooves 90 of the support.

[0109] A strip 10 of a plurality of optoelectronic components is arranged on the support with each of the optoelectronic components arranged at a distance from and facing the flat portion 31 of the lens of one of the optical fibers 1.1, 1.2, 1.3, 1.4. The strip 10 may or may not be directly arranged on the support. It may, for example, be mounted on an intermediate component itself facing the support 9.

[0110] An OSA optical subassembly illustrated in Figures 4 and 5 or in [Fig.7] can be integrated into an optoelectronic module.

[0111] Other variants and improvements may be provided without departing from the scope of the invention.

[0112] The shape and / or dimensions of the optical lens may differ from those illustrated and take any shape provided that the external surface incorporates a concave portion. They may for example be partially in the form of a right parallelepiped or the like... preferably so that the rounded portion 33 of the lens is set back inside the cylindrical envelope of the optical fiber.

Claims

Claims

1. Lensed optical fiber (1) comprising: - an optical fiber (2) with a longitudinal axis (X), the distal end (22) of which is a flat surface orthogonal to the longitudinal axis; - a main optical lens (3) with a single refractive index, arranged at the distal end of the fiber and the external surface of which is delimited at least by a concave portion (30) and a flat portion (31), parallel to or inclined at a non-zero angle with the longitudinal axis of the fiber;- a mirror (4) matching at least part of the concave portion of the main lens, the mirror being at least partly reflective in at least one given wavelength range, so that at least part of an optical beam (F) coming from the fiber and passing through the main lens is reflected by the mirror to exit through the plane portion (31) of the main lens or vice versa, that at least part of an optical beam passing through the plane portion of the main lens and passing through the main lens is reflected by the mirror to exit through the fiber.;

2. A lensed optical fiber according to claim 1, the main optical lens being fused with the optical fiber so as to form a single-piece element.

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

4. Lensed optical fiber according to one of claims 1 to 3, the external surface of the main optical lens also being delimited by a free end portion (32) of height (e) greater than or equal to 100 nm.

5. Lensed optical fiber according to one of the preceding claims, the external surface of the main optical lens being delimited by a right parallelepiped of which one face is the flat portion and another face is the free end portion of height (e).

6. Lensed optical fiber according to one of the preceding claims, the external surface of the main optical lens also being delimited by a rounded portion (33) at least partly matching the external diameter of the optical fiber.

7. Lensed optical fiber according to claim 6, the thickness (e') of the rounded portion (33) being greater than or equal to 100 nm.

8. Lensed optical fiber according to one of the preceding claims, the height (H) of the main lens being less than or equal to the external radius of the optical fiber.

9. Lensed optical fiber according to one of the preceding claims, the concave portion of the external surface of the main lens, and where appropriate of the additional one, being a biconical surface, preferably a double-paraboloid.

10. Lensed optical fiber according to one of the preceding claims, the material of the main lens, and where appropriate of the additional lens, being transparent in the given wavelength range, preferably between 800 and 1700 nm.

11. Lensed optical fiber according to one of the preceding claims, the material of the main lens, and where appropriate of the additional lens, being chosen from an epoxy, an acrylate or a combination thereof, an unsaturated polyester, a urethane, a sol-gel material.

12. Lensed optical fiber according to one of the preceding claims, the mirror being a metallic layer, preferably chosen from Au, Al, Ni, Ag, deposited on the concave portion of the main lens.

13. Lensed optical fiber according to one of claims 1 to 11, the mirror being a reflective dielectric layer in the given wavelength range.

14. Optical subassembly (6) comprising: - at least one lensed optical fiber (1) according to one of the preceding claims, - at least one optoelectronic component (7) arranged at a distance from and facing the flat portion of the main lens parallel to or inclined at a non-zero angle with the longitudinal axis (X) of the fiber.

15. Optical subassembly according to claim 14, the space between the optoelectronic component and the planar portion of the main lens, or where appropriate with the additional lens, being filled with air, transparent resin in the given wavelength range or a transparent adhesive in the given wavelength range.

16. Optical subassembly according to claim 14 or 15, comprising: - a support (9) comprising a plurality of grooves (90), preferably V-shaped, - a plurality of lensed optical fibers (1.1, 1.2, 1.3...) each positioned and locked in one of the grooves, - a strip (10) of a plurality of optoelectronic components, arranged on the support with each of the optoelectronic components arranged at a distance from and facing the flat portion of the main lens of one of the optical fibers.

17. Optoelectronic module, comprising at least one optical subassembly according to one of claims 14 to 16.

18. Method for producing a lensed optical fiber according to one of claims 1 to 13, comprising the following steps: i / positioning an optical fiber on a support, ii / cutting at 90°, in particular by cleaving, and preparing the distal end of the optical fiber, i / dipping or immersing the distal end of the optical fiber in a resin made of photopolymer material, iv / laser polymerization of the resin in order to form an external surface of the main optical lens delimited at least by a concave portion and a flat portion, parallel to or inclined at a non-zero angle with 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 external surface of the main lens, so as to form the mirror.

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