Abstract: An integrated optical isolator arrangement is described that is capable of isolating an input optical signal and coupling a pump signal. The coupler includes a pair of lenses with an isolator disposed therebetween. The isolator is sandwiched between a splitter/filter and a wavelength selective device. An end face of each lens has an input and an output port for receiving and transmitting optical signals. The splitter/filter is selected to transmit some of the input signal on a first input port and to reflect the remaining untransmitted portion of the input optical signal to a first output port proximate to the first input port. The wavelength selective device allows the input signal from the first input port to pass through it to a second output port, and in addition, reflects a pump signal transmitted on the second input port to the second output port for combination with the input optical signal.

Abstract: A light coupling device for coupling a light source to an optical fiber. The device includes a first cylindrical sleeve carrying a GRIN lens and a ferrule. The ferrule receives the optical fiber. Movability of the ferrule along the optical axis of a first through-hole in the first sleeve allows a determination of a focal length between the GRIN lens and an incident end face of the optical fiber. A first setting means sets a relative position of the ferrule with respect to the first sleeve for holding the two in position with respect to one another when the GRIN lens and the incident end face of the optical fiber are separated by a distance equal to the focal length therebetween. The device further includes a second cylindrical sleeve. The first sleeve is coaxially disposed within a second through-hole of the second sleeve, and a light source unit is concentrically disposed within the second through-hole.

Abstract: A laser system includes a laser diode source with a plurality of output facets. The laser diode source produces a divergent output along an emission path. A microlens is optically coupled to the diode source. The microlens receives the divergent output along the emission path and modifies the divergence of the output in a high numerical aperture direction of the microlens A power source is coupled to the laser diode source.

Abstract: A novel array of optical fiber beams collimator device, includes as novel mponents thereof an array of single beam collimator units. A housing is provided with a corresponding array of co-parallel lens bores between opposite sides of the housing. Each unit of the array of single beam collimator units is formed from a gradient index glass, rod-type, collimation lens disposed in the corresponding lens bore with a reinforced terminal end section of an optical fiber attached by its end face to the end face of the lens at one of the sides of the housing. The lenses of the array of units all have a common length dimension of one-quarter pitch plus a predetermined increment of length chosen for coupling maximum power through respective fiber optic lines.

Abstract: An optical fiber manifold is provided for coupling light from an illumination source to a plurality of spaced, large diameter output fibers, or "light pipes", which are used for a variety of purposes, such as illuminating pools, spas, hazardous material zones, jail cells, and other applications where direct lighting is dangerous, difficult to maintain, or subject to vandalism. The manifold comprises a light converging element, which may be either a lens or a reflector, for converging light separately on each of the spaced optical fibers. The light converging element is segmented, with each segment corresponding to one of the optical fibers, and is precise enough that substantially all of the convergent light is received by the respective cores of each of the spaced output fibers, thereby minimizing light loss.

Abstract: A device for splitting an optical beam into two beams propagating along different optical paths, is provided. The device includes a pair of graded index collimating lenses having their planar collimating ends aligned such that they are both inwardly facing and share a common optical axis. A partially transmitting partially reflective material is disposed between the lenses. At least one of the planar endfaces of the collimating ends are wedge shaped such that a non-zero angle is formed between the two endfaces. This non-zero angle reduces the effect of unwanted optical interference.

Abstract: A device for coupling light from a light source to one or more light pipes is described. The device allows for direction of light from a single source through multiple light pipes with minimal loss of light. The device also minimizes heating of the light pipes and provides for an even light intensity distribution over several light pipe surfaces. Potential applications include automotive lighting and interior lighting.

Abstract: Connecting device for axial connection of the end portions of at least one optical fibre with another, which are fixed in at least one plug each provided in a coupling house, in order to provide an optical connection between the fibres via a lens connectable to each fibre end, each lens is constituted by a lens body, the front end surface of which is partially spherical and the opposite, rear end surface of which is arranged perpendicular against the longitudinal axis of the lens body. In the coupling house a ring shaped, partially spherical or conical seat is provided for the front end surface of the lens body, which seat is concentric with the longitudinal axis of the coupling house. The plug is insertable in a coaxial guide sleeve guided in the coupling house.

Abstract: An object of the present invention is to provide an optical passive component having a polarization-independent optical isolator for constituting an optical fiber amplifier and exhibiting an optical isolator function. At least first and second optical fibers for input and output of light rays, a birefringent crystal, a lens for converting the input light rays into nearly collimated rays, a magnetooptical crystal for receiving a magnetic field so as to rotate by .pi./8+N.pi./4(n=0, 1, . . . ) the polarization direction of the input light rays, and a reflector are disposed in order. A half wave plate is provided to cover one portion of the ray path between the above described birefringent crystal and the above described lens.

Abstract: An improved optical switch having a first optical fiber and a plurality of N optical fibers. The first optical fiber forms an optical path with any one of the N optical fibers by an alignment of a longitudinal axis of an end of the first optical fiber with a longitudinal axis of an end of the one of N optical fibers. A switch in optical path is performed by a relative movement of the first optical fiber with respect to the N optical fibers for a realignment of the longitudinal axis of the end of the first optical fiber with a longitudinal axis of an end of another one of the N optical fibers.

Abstract: An optical fiber receptacle has a glass rod lens in its one end side and a front end of an optical fiber to be connected to the opposite end side of the receptcle is brought into physical contact with a spherical surface of the glass rod lens to thereby make the optical fiber optically couple with an optical element to be provided on the glass rod lens side, wherein a housing including a sleeve for insertion of the front end of the optical fiber therein is fixed to a lens holder for fixedly holding the glass rod lens by fusion so that the center of the sleeve and the center of the spherical surface of the glass rod lens are aligned.

Abstract: An endoscope has a first end for insertion into a body, or other visually obscured area, with an optical image-forming lens device in the first end for forming two, side-by-side images of an object on opposite sides of the central axis of the endoscope. The images are transmitted to the opposite end of the endoscope, where they are received by a viewing device for three-dimensional viewing of the images by an operator. An image converging mechanism is provided in the image paths to provide a suitable convergence angle between the images at the viewing device.

Abstract: An optical system comprising a monomode main optical fiber coupled to a phototransducer, by means of an assembly between the monomode optical fiber and the phototransducer, which assembly comprises, in succession: a piece of graded index multimode fiber, a piece of step index multimode fiber, and a microlens.

Abstract: An optical isolator is placed in the path of an input optical fiber and an output optical fiber, the optical isolator comprises: a first GRIN lens for receiving rays emitted from the input optical fiber and converging into parallel rays; a first birefringent crystal wedge for splitting the parallel rays into a first ray polarized along the birefringent crystal's optical axis and a second ray polarized perpendicularly to the optical axis; a second birefringent crystal wedge for recombining the first ray and the second ray wherein at least one of the first birefringent crystal wedge and the second birefringent crystal wedge comprises a birefringent crystal of YVO.sub.

Abstract: A small diameter multimode optical fiber with a low numerical aperture (i.e., 0.1) is used as a microlens to collimate the output emissions of a laser diode before butt coupling the output of the laser diode to an optical fiber. The optical fiber used as the microlens is chosen such that its diameter roughly equals the diameter of the fiber to be coupled to the laser diode. One end of the fiber is mounted in a fixed position and the other end of the fiber is slip fit into the end of a hollow receiving member mounted in a fixed position and running parallel to the axis of the fiber. The collimation is performed in the high NA direction of the output of the laser diode. The output of a bundle of butt coupled optical fibers may be used to pump a laser system.

Abstract: There is provided an apparatus for improving power transfer or collection efficiency from a high aspect ratio linear junction laser diode to associated collimation optics in a weapon rangefinder, illuminator, laser spot projector, optical security system, or other optical device. A cylindrical or rod lens (16) is positioned adjacent to the emitting region (14) of the laser diode (10), the longitudinal axis of the rod lens (16) being parallel to the emitting region (14). Preferably, the emitting region (14) of the laser diode (10) is located at the bottom of a V-shaped surface (20) of the laser diode (10), for facilitating alignment of the rod lens (16) with the emitting region (14).

Abstract: In a semiconductor laser device used as an optical time domain reflectometer, a polarizer is inserted in the path of the laser light. The plane of polarization of the polarizer is aligned to the plane of polarization of the emitted laser light, and the polarizer transmits the emitted laser light without attenuation. A reflected laser light from an optical fiber under test is a non-polarized light and receives a substantial attenuation by the polarizer. Thus, problems associated with reradiation echoes are prevented.

Abstract: An optical coupler comprises at least one optical fiber (1), one laser (2), one photodiode (3), one focusing lens (30) for focusing on the fiber and one plate (41) which reflects the rays coming from the fiber (1) towards the photodiode (3). In order to prevent a ray sent out by the laser (2) from returning to the photodiode (3) after reflection on the input diopter (4) of the lens (30), the optical axis is broken at the height of this diopter (4) by means of a prism (5). The reflected rays do not return to the plate (41).

Abstract: In an optical fiber functional device for processing a light beam between optical fibers, single-mode optical fibers for processing the light beam are concentrically connected at the mutually opposed ends to convergence-type rod lenses each having a prescribed length and made of a graded-index optical fiber.

Abstract: An optical device manufacturing method includes a step of accumulating an optical device inorganic material on a stamper by use of a vacuum thin-film growing method, and a step of removing the accumulated material from the stamper, thereby producing an optical device.

Abstract: An improved optical switch having a first optical fiber and a plurality of N optical fibers. The first optical fiber forms an optical path with any one of the N optical fibers by an alignment of a longitudinal axis of an end of the first optical fiber with a longitudinal axis of an end of the one of N optical fibers. A switch in optical path is performed by a relative movement of the first optical fiber with respect to the N optical fibers for a realignment of the longitudinal axis of the end of the first optical fiber with a longitudinal axis of an end of another one of the N optical fibers.

Abstract: A light source to optical fiber coupling device comprising: a diamond coupler, a light source located at an end of the diamond coupler, an optical fiber having an end which is adjacent the other end of the diamond coupler, the optical fiber being in optical coupling relation with the diamond coupler.

Abstract: Optical passive components comprising: a first optical fiber for outputting pumping light; a second optical fiber for receiving the pumping light and either outputting or receiving signal light; a third optical fiber for either receiving or outputting the signal light; a wavelength selecting filter which transmits therethrough the pumping light and reflects the signal light; a mirror which reflects most of the signal light reflected by the wavelength selecting filter and transmits therethrough a portion of the signal light reflected by the wavelength selecting filter such that the wavelength selecting filter and the mirror form an optical assembly; an optical isolator which passes therethrough the signal light reflected by the mirror so as to output the signal light; and a semiconductor optical detecting device for detecting the signal light transmitted through the mirror; wherein the first, second and third optical fibers are disposed at one side of the optical assembly.

Abstract: According to this invention, a semiconductor laser device includes a coaxial package and a semiconductor laser chip. The semiconductor laser chip is incorporated in the package such that an emission position of the semiconductor laser chip is shifted from an axis of the package.

Abstract: In a system for measuring moisture content of powder, such as powdered milk while the powder is being dried, the powder is contained in a fluidized bed and a fiber optic probe is inserted through the wall of the container of said bed to be immersed in the fluidized bed. The fluidized bed continuously scrubs the outer surface of the probe window and prevents it from being coated with the powder. Near infrared light is transmitted through a cable optic fiber and said probe to irradiate the powder in said fluidized bed and is reflected back from the powder into said probe and transmitted by said fiber optic cable to a spectroscopic analyzing instrument. The fiber optic probe includes a sapphire rod having a back surface abutting the end of the fiber optic cable and an angled front surface. The front of the probe is closed by a quartz window spaced from the angled front surface of the sapphire rod and held in position by an inwardly directed flange on the outer tubular casing of the fiber optic probe.

Abstract: A method for the use of light pressure to optically center a lens on a source of emitted light with submicron accuracy. In one aspect the method uses light pressure to optically center a lens on a source of emitted light, where the lens is then fixed in place. In another aspect the method uses light pressure to create an optically centered lens from a dielectric liquid on a source of emitted light, the shaped lens is then fixed to form an optically aligned permanent lens. By choosing the appropriate lens the light emitted from the source can be either focused or collimated.

Abstract: A semiconductor laser module is provided by silver soldering the holder part of Kovar to the package of Kovar, and then silver soldering the lens holder part of pure iron or a stainless steel to the holder part. The lens holder part has the convergent rod lens fixedly soldered thereto by an Au/Sn solder of a high melting point of 280.degree. C. The semiconductor laser is fixedly soldered onto a stem, with the stem, the optical fiber and ferrule holder being fixedly soldered at positions so that the light emitted from the semiconductor laser is converged by the convergent rod lens at the light incidence end of the optical fiber and the laser light is coupled to the optical fiber. Thus, the convergent rod lens can be fixed with high-melting-point joining means, and a semiconductor laser module for optical communications in which the deterioration of light connection repeatedly generated by heat stress is suppressed can be obtained.

Abstract: The invention discloses a cylindrical optical radiating device for obtaining controlled light distribution in a cylindrical pattern from an optical fiber. The device is constructed of a solid cylindrical tip made from material containing an optical scattering material in which a tapered central lumen having a conical shape has been drilled, cast or bored. Light emerging from the end of the fiber is radiated out in a cylindrical pattern through the use of the tapered central lumen.

Abstract: A method of attaching a Gradient Index (GRIN) lens to an optical fibre in the course of making an optical instrument for use at a working distance. The method is especially suitable for making an optical instrument with an extended working distance. In the method, a test object, a GRIN lens, and an optical fibre are provided. The GRIN lens is placed at the working distance from the test object, and is axially aligned with the test object. The optical fibre is placed adjacent to, and axially aligned with, the GRIN lens to form an image of the test object at the proximal face of the optical fibre. The distal face of the optical fibre is placed adjacent to the proximal face of the GRIN lens. At least one of the GRIN lens and the optical fibre is moved axially with respect to the other until the image of the test object is in focus. This determines an optimum axial spacing between the GRIN lens and the optical fibre.

Abstract: Apparatus for end-pumping of a solid-state laser with a source of high optical brightness. A stack of diode laser bars are excited, and each bar emits a light beam of a selected pump wavelength in a chosen direction. The light beam output of the diode bar stack is divided into a plurality of smaller, approximately rectangular light beams, which serve as extended light sources, by a plurality of mirrors that are positioned to receive one or more of these smaller beams and redirect such beams onto first, light-receiving ends of one or more optical fibers. Light collection optics receive the beams issuing from the mirrors and focus these beams onto a light-receiving end of an optical fiber with beam convergence angles that are appropriate for the numerical aperture of that fiber.

Abstract: An optical device which controls the strength of an optical signal from an input fiber to an output fiber responsive to a signal on a control terminal. The device has a first GRIN lens associated with the input fiber, a first birefringent polarizer, a liquid crystal cell, a second birefringent polarizer and a second GRIN lens associated with the output fiber. The liquid crystal cell, located between the first and second polarizers and connected to a control terminal, controllably rotates the optical signal from the optical axis of the first polarizer toward the optical axis of the second polarizer responsive to the signal on said control terminal. The operation of the device is independent of the polarization of the optical signal in the input fiber. Furthermore, the device can be operated as an optical switch or an optical attenuator by suitably arranging the axes of the polarizers and liquid crystal cell.

Abstract: An optical assembly for an LED printhead includes a longitudinally extending linear lens array. A stiffener bar is attached to the lens array along a substantial longitudinal dimension of the lens array. A lens mount base plate supports the stiffener bar and a pin and slot connection is provided for permitting thermally induced dimensional change in two dimensions of the stiffener bar relative to the lens mount base plate.

Abstract: A method is disclosed for use in the fabrication of a passive multi-channel ptical fiber rotary joint having an axis of rotation and of the type in which optical fiber communication channels are coupled via bilaterally symmetrically disposed miniature-collimation-lenses as collimated beams to one and the other sides of an image-derotation-prism-and-prism-rotational-drive-subassembly prism which rotates at a predetermined ratio of the relative rotation of the sides of the rotary joint to derotate optical propagation paths across the transverse rotary interface associated with the respective ones of the miniature collimation lenses. Each channel at each side of the rotary joint includes a fiber and lens junction at which a ferrule encased fiber termination couples to the axially outwardly disposed face of the miniature collimation lens. A lens array holding piece serves as the mount for this junction.

Abstract: In an optical coupling system for a fiber laser, a cylindrical lens extends parallel to a number of aligned light sources and a series of aligned input ends of optical fibers facing the light sources. Output ends of the fibers pass light to a solid state medium in a laser cavity. A block with precision grooves holds the fibers to align them with the lens and the images of the light sources. The cylindrical lens is biaspheric with a longitudinal axis and two refractive surfaces whose axially transverse cross-sections follow paths other than the paths of a conic section.

Abstract: Dual transmitter-receiver repeaters are provided on a GRIN rod lens optical bus to boost the optical signals that are transmitted on the bus. Only one of the repeaters is operative as a repeater at a time such that when an activated repeater fails, the other repeater is activated to operate as a repeater to replace the failed one. Repeaters, in alternate embodiments, may be located together on the optical backplane, may be on adjacent cards on the electrical backplane, may be on separate cards located at opposite ends of the optical backplane, or may be located on the same card on the electrical backplane. When the repeaters are located on adjacent cards on the electrical backplane, a prism is secured to the last optical tap prism in the transmitting light path to allow the repeaters to communicate with the information processing receivers and transmitters of the optical bus.

Abstract: A gradient-index (GRIN) rod lens for use in an optical receiver, in which the end face of the GRIN rod lens opposite a photodetector is bevelled. The resulting optical receiver achieves an optical return loss which is >10 dB higher than known optical receivers having a bevelled end solely on an optical launch side of the GRIN rod lens.

Abstract: GRID rod lenses extend between the faces of beam-splitting prisms that are in the transmitting and receiving light beam paths of an optical backpanel bus. The GRIN rod lenses are secured in segments to the inner opposing faces of pairs of beam-splitting prisms along the light beam paths with optical grade epoxy in order to reduce undesirable reflections when vibrations occur. These GRIN rod lenses are contained in a Kovar channel which has a pair or elongated V-shaped grooves. Kovar is the preferred material because it has approximately the same index of expansion as the GRIN rod lenses. The GRIN rod lenses of the transmitting path are secured in one V-shaped groove while the GRIN rod lenses of the receiving path are secured in another V-shaped groove.

Abstract: The invention relates to an optoelectronic device comprising a semiconductor laser enclosed in an envelope, an optical fibre coupled to the semiconductor laser, and further coupled to at least one optical isolator and an outgoing optical fibre (pigtail). According to the invention, the semiconductor laser and the optical isolator are each enclosed in a separate module. The laser module mainly provides space to the semiconductor laser and to an optical fibre coupled thereto and ending in a ferrule in a tubular projection of the laser module. The module for the optical isolator is tubular in shape and contains in that order a first graded index lens, an optical isolator, a second graded index lens, and an outgoing optical fibre (pigtail) coupled to this second graded index lens through a ferrule.

Abstract: A thermistor assembly is formed by fixedly attaching a thermistor on to a base formed of a material having good heat conductivity and the thermistor assembly and an LD chip are fixedly attached on to a carrier arranged in contact with an electronic cooling element using brazing materials with different melting points, so that, when, for example, the thermistor is found faulty, the thermistor can be easily exchanged with a good one.

Abstract: A coupler for a fiber optic light waveguide has phase space matching optics to increase coupling efficiency. The acceptance phase space of the fiber optic waveguide has two components for light in two orthogonal planes. One of the phase space plots has a straight spine and the other has a bent spine. The phase space matching optics include a graded index lens optically coupled to the phase of a light emitting diode, in the case of a write coupler, which alters the emitted light phase space at a reference plane of the emitted light to match, at the reference plane, the acceptance phase space component having the straight spine. Another lens takes the output light from the graded index lens and alters the phase space further to match the phase space component having the bent spine.

Abstract: A photosemiconductor module such as a laser diode module or a photodiode module is optically coupled to an optical fiber. The photosemiconductor module includes a holder assembly with a photosemiconductor and a lens being fixedly mounted therein coaxially along an optical axis. An optical connector is joined to the holder assembly and has a hollow receptacle to be connected to the optical fiber and a joint press-fitted in the receptacle and joined coaxially to the holder assembly by lap laser beam welding.

Abstract: A circuit arrangement is provided for allowing the bidirectional exchange of received and transmitted signals over a single monomodal optical fiber. The light transmitter (usually a laser or a LED), the receiver of optical signals and an optical system suitable for directing the optical signal to be transmitted to the monomodal optical fiber ad for directing the optical signal from the monomodal optical fiber to the receiver collects the signals in one passage. The optical system uses an optical transceiver employing a light transmitter and a light receiver. This optical transceiver is formed in a unitary housing. The optical system includes first and second lenses which may be graded-index waveguide sections and a planar filter disposed therebetween, the planar filter typically being an interferential filter. The optical system is formed on a support which allows the light transmitter which is typically a laser to be disposed directly adjacent one of the lenses.

Abstract: A graded index lens having one end-surface thereof adapted for connection to an optical fiber or the like characterized by an axially asymmetrically tapered end portion terminating in the end-surface.

Abstract: A robust optic fiber coupler which connects to an optic fiber cable via a quick disconnect optic fiber connector. The robust coupler contains a GRIN lens positioned in a bore through the coupler axially aligned with the optic fiber. The GRIN lens acts to expand and collimate input/output optic signals which are then passed through a protective window in the axial bore and emitted from the end plate face of the robust coupler. The optic signals are coupled between two optic fiber cables, each fitted with a subject robust coupler, when the coupler end plate faces are positioned adjacent to each other with each axial bore and associated GRIN lens and optic fiber commonly and axially aligned through a process such as a robotic arm and end effector connection.

Abstract: An optical waveguide array includes a two-dimensionally refractive index profile lens for focusing light beams in a scanning direction. The two-dimensionally refractive index profile lens is bonded to or integrally formed with the optical waveguide array. The refractive index is distributed in the two-dimensionally refractive index profile lens by changing the irradiation energy of ultraviolet ray during the manufacture. As a member for focusing the light beams in the irradiation direction which is perpendicular to the scanning direction, another two-dimensionally refractive index profile lens or a cylindrical lens is used. The optical waveguide array with such an inexpensive structure can focus the light beams both in the scanning direction and the irradiation direction. The resolution of the latent image formed on a photosensitive member can thus be improved.

Abstract: A rod lens fixing method which can prevent the generation of cracks in a rod lens due to annealing to be carried out after welding a lens assembly. The rod lens fixing method includes the steps of providing a flanged split sleeve having an axial slit extending continuously from one end of the flanged split sleeve to the other end thereof, the axial slit being wide enough at least a flange of the flanged split sleeve to permit laser welding; press-fitting the rod lens into the flanged split sleeve; and applying a solder into the axial slit to solder the rod lens to the flange split sleeve. This method further includes the steps of inserting the flanged split sleeve into a bore formed at one end portion of a sleeve, the bore having a diameter larger than an outer diameter of the flanged split sleeve and smaller than an outer diameter of the flange; and laser-welding the flange to one end surface of the sleeve at a plurality of points on an outer circumference of the flange and in the axial slit.

Abstract: An optical power summing apparatus that allows a multiplicity of optical signals to be combined with minimal signal transmission loss. A single photodiode simultaneously receives all of the input signals to perform a summation of signal powers. Alternative embodiments of the apparatus use either a tightly packed bundle of etched optical fibers or a converging arrangement of optical waveguides on a dielectric substrate to focus the optical signals onto the base region of a single photodiode.

Abstract: A small diameter multimode optical fiber with a low numerical aperture (i.e., 0.1) is used as a microlens to collimate the output emissions of a laser diode before butt coupling the output of the laser diode to an optical fiber. The optical fiber used as the microlens is chosen such that its diameter roughly equals the diameter of the fiber to be coupled to the laser diode. The collimation is performed in the high NA direction of the output of the laser diode. The output of a bundle of butt coupled optical fibers may be used to pump a laser system.

Abstract: An optical package includes a housing composed of two sections, a first section and a second section connectable to the first section. A laser holder is connected to the first section of the housing and adapted to hold a laser assembly. A fiber holder is connected to the second section of the housing and includes a ferrule by which an optical fiber is held. A rod lens is mounted within the housing to focus optical emission from the laser assembly on the optical fiber. The laser assembly includes a semiconductor element. Radial alignment of the semiconductor element and the laser holder is performed before the laser holder is secured to the first section of the housing. Axial alignment of the rod lens and the semiconductor element takes place while the laser holder is being fit in the first section of the housing. The second section of the housing is then moved in a radial direction relative to the optical axis of the semiconductor element and is, then, laser welded to the first section of the housing.

Abstract: A DFB laser (2) is coupled to a monomode line fiber (14) via an isolator constituted by a Faraday rotator crystal (4) and a polarizing fiber (10) which is welded to a fiber to be coupled (14). A focusing lens (8) is integrated in an intermediate block including the rotator crystal (4) and a permanent magnet (6). The invention is particularly suitable for making light-emitting heads for use in optical fiber telecommunications systems.