EP4165737A1 - Amplificateur à fibre ou laser à fibre - Google Patents

Amplificateur à fibre ou laser à fibre

Info

Publication number
EP4165737A1
EP4165737A1 EP21733391.3A EP21733391A EP4165737A1 EP 4165737 A1 EP4165737 A1 EP 4165737A1 EP 21733391 A EP21733391 A EP 21733391A EP 4165737 A1 EP4165737 A1 EP 4165737A1
Authority
EP
European Patent Office
Prior art keywords
pump light
fiber
laser
glass fiber
active glass
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21733391.3A
Other languages
German (de)
English (en)
Inventor
Thomas Theeg
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fiberbridge Photonics GmbH
Original Assignee
Fiberbridge Photonics GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fiberbridge Photonics GmbH filed Critical Fiberbridge Photonics GmbH
Publication of EP4165737A1 publication Critical patent/EP4165737A1/fr
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • H01S3/094007—Cladding pumping, i.e. pump light propagating in a clad surrounding the active core
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/0675—Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067—Fibre lasers
    • H01S3/06754—Fibre amplifiers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre

Definitions

  • the present invention relates to a fiber amplifier or a fiber laser according to the preamble of claim 1 and a laser system with such a fiber amplifier and / or with such a fiber laser according to claim 14.
  • Glass fibers are usually drawn as thin threads from a glass melt, so that a glass fiber is a long, thin fiber made of glass.
  • Glass fibers can be used, for example, as a textile fabric for thermal insulation and / or for sound insulation. Short pieces of glass fiber are also usually mixed with plastics in order to improve their mechanical properties; such components can be referred to as glass fiber reinforced plastics.
  • glass fibers are used for light transmission.
  • glass fibers are used for data transmission by means of light; in this case the glass fibers can also be referred to as optical waveguides or as passive glass fibers.
  • Glass fibers are also used in medicine, for example, for lighting and for generating images, for example in microscopes, in inspection cameras and in endoscopes.
  • glass fibers are used in sensors, which can then be referred to as fiber optic sensors.
  • the laser radiation can be conducted as signal light radiation by means of a passive glass fiber from a laser radiation source as a signal light source or as a signal light radiation source to a processing point, for example in material processing or in medicine Cutting or welding.
  • the laser beam can also be supplied as laser radiation in this way, for example in measurement technology, in microscopy or in spectroscopy, to a sample, for example.
  • Passive glass fibers can be used to conduct a laser beam, for example, in mechanical engineering, telecommunications, medical technology and sensor technology. Glass fibers can also be used to generate or amplify laser light and are referred to as active glass fibers.
  • Fiber lasers for generating laser light or fiber amplifiers for amplifying laser light have a doped fiber core in sections (see below) which forms the active medium of the fiber laser or the fiber amplifier, ie its active glass fiber.
  • Customary doping elements of the laser-active fiber core are in particular neodymium, ytterbium, erbium, thulium and holmium.
  • Such fiber amplifiers are usually pumped optically by coupling additional radiation, for example from diode lasers or other radiation sources, as pump light into the fiber cladding or directly into the fiber core, parallel to the signal light fed into the fiber core from outside.
  • additional radiation for example from diode lasers or other radiation sources
  • the pump light in a fiber amplifier is radiated into the active glass fiber in the direction of propagation of the signal to be amplified, it is typically referred to as "forward pumping". If the pump light is radiated into the active glass fiber against the direction of propagation of the signal to be amplified, it is typically referred to as “backward Pumping ". This can also take place as “bidirectional pumping" in both directions.
  • the laser radiation which is guided through the laser-active fiber is usually very intensified due to the great length of the active glass fiber.
  • the pump light from diode lasers or other radiation sources is also coupled into the fiber cladding or directly into the fiber core, so that the laser radiation is generated and amplified directly within the glass fiber.
  • a signal light source outside the fiber laser can therefore be dispensed with.
  • the signal light is reflected as completely as possible at one end of the glass fiber and to a certain extent at the opposite end and is also coupled out to the outside of the fiber laser.
  • So-called fiber Bragg gratings (FBG) are usually introduced into the fiber core as reflectors or mirror elements, which are usually called “high reflective” (HR), ie as highly reflective fiber Bragg grating, and as "output coupler" (OC ), d. H. referred to as the low reflectivity of the fiber Bragg grating.
  • the two reflectors (HR and OC) then form the resonator for generating the laser radiation as signal light from the fiber laser.
  • Glass fibers which are used to amplify the signal light such as the laser radiation in fiber amplifiers or to generate laser radiation in fiber lasers, usually have a fiber core, which consists of pure glass such as pure quartz glass and in the case of passive glass fibers is often doped with germanium; In the case of active glass fibers, doping as described above is usually used. In certain cases, the fiber cladding can also be doped; this applies to passive and active glass fibers. Depending on the size and the numerical aperture of the fiber core, a distinction can be made between single-mode and multi-mode glass fibers. In addition, the fiber core can still have polarization-maintaining properties for the light.
  • the fiber core is usually radially from the outside of at least a fiber cladding (English: fiber cladding), which is usually closed in the circumferential direction and thus completely surrounds the fiber core, apart from the two open ends of the glass fiber.
  • Both passive glass fibers and active glass fibers are usually surrounded by a fiber coating made of, for example, polymer comparable to the fiber cladding, which can then be assigned to the glass fiber.
  • the fiber coating can serve to mechanically protect the glass interior of the glass fiber and influence its optical properties.
  • the fiber coating is primarily used for mechanical protection. Glass fibers that guide light in the fiber core and in the fiber cladding (English: double-clad glass fibers) are usually carried out with a fiber coating to meet mechanical and optical properties.
  • Two cross-sectional shapes for the fiber cladding that occur frequently in practice are cylindrical and octagonal.
  • the octagonal shape for the fiber cladding is used in particular for active glass fibers.
  • Such glass fibers can be produced in great lengths and are usually available as Rollewa ren.
  • the diameter of the fiber cladding usually varies between approx. 80 ⁇ m and approx. 1 mm. In practice, especially with the larger fiber diameters, one often speaks of fiber rods (English: rod-type fiber).
  • Fiber lasers or fiber amplifiers usually consist essentially of at least one active glass fiber, as described above, of various fiber components each with at least one passive glass fiber, at least one pump light source, preferably in the form of diode lasers, and various electronics.
  • the active glass fiber is doped, for example, with ytter bium, erbium, thulium or neodymium, depending on the emission wavelength, as mentioned above.
  • the laser radiation is generated in the active glass fiber in a fiber laser or amplified in a fiber amplifier and can accordingly be used for various applications.
  • Fiber lasers or fiber amplifiers are used, among other things, in the industry for ultra-short pulse laser systems (for example at a wavelength of approx. Lpm), in measurement technology (for example for LIDAR measurements - laser detection and ranging), in medical applications (for example in a Wavelength of approx. 2pm) or in space applications (for example at a wavelength of approx. 1.5pm).
  • the laser radiation is typically generated or amplified in the active glass fiber, as previously described be.
  • radiation can also be absorbed or weakened in active glass fibers.
  • the passive glass fiber is used in a fiber amplifier as well as in other fiber arrangements. genes exclusively for the transport of the radiation over a certain fiber route, for example for the supply or removal of laser radiation from the active glass fiber.
  • a signal light radiation input as an interface for the feed or for the coupling in of the signal radiation to be amplified as input radiation from outside the fiber amplifier a pump light coupler which transfers the pump light radiation from the pump light source into the jacket of the transports active glass fiber, a pump light trap that picks up unabsorbed pump light from the active glass fiber, and a signal light radiation output that shapes and / or guides the output radiation and thereby decouples it to the outside of the fiber amplifier and makes it available.
  • an optical window with an anti-reflection coating on one side for the corresponding wavelengths or a lens for collimating the output radiation can serve as the signal light radiation output or fiber exit optics.
  • the fiber exit optics can also be another glass fiber that guides the output radiation to a destination.
  • a pump light coupler In the case of a fiber laser, a pump light coupler, an active glass fiber, a pump light trap and a fiber exit optic are usually also used. Since no signal radiation is supplied from outside here, but the laser radiation is generated inside the fiber resonator between the two reflectors or mirror elements, there is no signal light radiation input.
  • US 2018/159296 A1 describes a system and a method whose integrated signal light source and high-performance pump source generate two wavelengths outside the effective amplification bandwidth of a single amplification medium without using two individual pump sources in a fiber amplifier train.
  • the system and method uses a single pump power oscillator that passes a wavelength of a signal light source losslessly and with minimal gain to pump integrated amplifiers in both directions (forward and backward), resulting in an amplification of the wavelength of a signal light source.
  • US Pat. No. 8,462,426 B1 describes a method for increasing the output power of monolithic Yb-doped fiber amplifiers with a narrow line width by suppressing the simulated Brillouin scattering.
  • the fiber amplifier uses a co-propagating geometry and is fed with broad (source 2) and narrow (source 1) line width signals that differ sufficiently in wavelength to allow efficient gain competition and a favorable temperature profile at the output end of the fiber.
  • the broadband signal light signal has the higher emission and absorption cross-sections. If source 2 also receives a sufficiently higher input power than source 1, it will be amplified to its maximum value when the signal light signals reach the central part of the gain fiber.
  • the signal light signal with the lower emission and absorption cross-section (signal 1) continues to be amplified Transfer of power from both the signal light signal and the pump light, resulting in an output power well in excess of the maximum value that would have been achieved if the amplifier had been illuminated with a single frequency beam.
  • the two signals are carefully selected so that significant quantum defect heating occurs during power transfer, a steep thermal gradient will develop, which will further increase output power.
  • US 2019/067895 A1 describes an erbium-doped fiber with a polarization-maintaining, very large mode area (PM VLMA) and a polarization-maintaining, Er-doped VLMA amplifier.
  • a polarization-maintaining amplifier with very large mode area consisting of an optical fiber with an input side, with an output side, with an optical core area with a longitudinal axis, the optical core area comprising a concentration of erbium and a diameter of about 50 pm, with at least one stress core with a longitudinal axis, the longitudinal axis of the at least one stress core running essentially parallel to the longitudinal axis of the core area, and with a cladding area which surrounds the core area and the at least one stress core, the core area containing at least one
  • the stress core and the cladding region are configured to support and guide the propagation of the signal light and signal contained therein in the direction of the longitudinal axis of the core region, the optical fiber having a birefringence beat length of more than about 14 mm.
  • the polarization-maintaining amplifier further comprises a pump laser, a signal light laser and a polarization-maintaining wavelength multiplexer, said pump laser and said signal light laser being connected in such a way that they feed light into the multiplexer, and the multiplexer is connected in such a way that it Feeds light into the input end of the optical fiber.
  • the fiber arrangement is realized with splice connections. This means that the pump light and signal light are supplied in passive glass fiber and the passive glass fiber is then connected to the active glass fiber via a splice connection.
  • WO 2011/160646 A1 describes a single-mode optical fiber for guiding an optical signal.
  • the core portion of the optical fiber is capable of guiding an optical signal in a fundamental core mode at an optical signal wavelength.
  • a cladding area is arranged to surround the core area and includes an inner cladding area and an outer cladding area.
  • the inner cladding region includes a background material and a plurality of inner clad features disposed in the background material, wherein a plurality of the plurality of inner clad features are of a first feature type.
  • the first type of feature includes an air vent surrounded by a high index region comprising a high index material that is greater than the index of refraction of the backing material of the interior liner.
  • the majority of the features of the first type support an optical mode having an effective index of refraction that is lower than the effective index of refraction of the fundamental kernel mode at the optical signal wavelength.
  • the optical fiber can comprise an active material and can be used as a cladding-pumped fiber amplifier. Glass fibers with a complex structure are described for which no optically compatible passive glass fibers are usually available. Therefore, no corresponding fiber components can be manufactured with passive glass fibers. As an alternative solution, free-jet optics are used in combination with the active glass fiber, which, however, loses the advantages of fiber technology.
  • the advantage of using both passive glass fibers and active glass fibers in combination with one another is that the passive glass fiber is usually significantly less expensive per unit length than the active glass fiber. This can keep the costs of the corresponding fiber amplifier or fiber laser as a whole low.
  • the guided laser light is not amplified or absorbed or weakened in the passive glass fiber. Therefore, on short passive fiber links of a few meters, there are almost no significant optical power losses with passive glass fibers.
  • optical fiber components have been manufactured from passive glass fibers for around 40 years and then connected to the active glass fiber in order to implement a fiber amplifier or a fiber laser, as described above.
  • fiber lasers and fiber amplifiers require at least one pump light source, for example in the form of several diode lasers and the active glass fiber as active fiber components, in addition to the fiber components with passive glass fibers.
  • the active glass fiber is usually spooled, ie wound as a coil, used in order to provide the longest possible distance for absorption of the pump light with a small volume or with little space required and at the same time to enable a compact design of the fiber laser or the fiber amplifier .
  • a signal light is usually used as input radiation in fiber amplifiers, which is generated externally to the fiber amplifier and coupled into the fiber amplifier as a further fiber component with passive glass fiber via the signal light radiation input.
  • the signal light radiation output as a fiber exit optics typically represents a further fiber component with additional passive glass fiber such as a fiber end cap with passive glass fiber for both fiber amplifiers and fiber lasers. This also applies to the two reflectors of a fiber laser.
  • the optical components are typically manufactured by glass fiber processing companies with passive glass fiber. Laser manufacturers acquire such individual components or individual parts with passive glass fibers, the active glass fibers and the pump light sources and integrate the individual parts with their expertise in relation to the arrangement, the fiber lengths and other system parameters respective manufacturer-specific fiber amplifiers or fiber lasers.
  • the end-face connection of the passive glass fibers of the individual components with one another and with the active glass fiber is made by means of welding processes and can also be referred to as splicing.
  • the positioning of the individual optical components with passive glass fibers has considerable advantages. Even with a certain amount of production scrap, due to the fact that the manual production of the fiber components is still predominantly present today, the production costs can be kept economically within limits.
  • the passive fiber components can be implemented with short passive fiber sections (typically approx. 1 m to approx. 2 m), since the connection of the optical fiber components and the choice of the precise fiber lengths are made afterwards by the laser manufacturer. This facilitates the handling of the hoisting position enormously.
  • Another essential advantage of individual components with passive glass fibers is that the fiber components in the fiber amplifier or in the fiber laser do not have any undesirable absorption behavior, as already mentioned above.
  • fiber areas not supplied with pumped light could absorb the laser signal as signal light and thereby at least weaken it and change its spectral shape. This is due to the fact that the absorption behavior of the laser signal as signal light in the active glass fiber is wavelength-specific. Depending on the type (for example Nd, Yb, Er, Tm etc.) and concentration of the doping of the active glass fiber as well as other parameters, changes in the absorption behavior can occur.
  • the spectral properties of the laser signal or the laser pulse can be significantly changed by absorption in an active glass fiber, i.e. in non-pumped sections of an active glass fiber.
  • a fiber section of an active glass fiber that is about 20 cm to about 50 cm long and not supplied with pump light can make ultrashort laser pulses unusable for the application.
  • the absorption of the laser signal in non-pumped sections of an active glass fiber can generate spectrally shifted radiation through amplified spontaneous emission (ASE for short). This can result in parasitic laser processes in the active glass fiber. Furthermore, areas of the fiber component with active glass fiber that are not supplied with pump light could even lead to damage or destruction of the fiber amplifier or the fiber laser due to the uncontrolled development of laser radiation.
  • the welded connections between passive and active glass fibers can sometimes only be implemented with certain restrictions or sometimes not at all qualitatively good and repeatable.
  • Another disadvantage is that when welding or splicing passive glass fibers and active glass fibers, the complications that can result from the welded connections can potentially increase.
  • passive glass fibers typically can be doped with germanium or fluorine and active glass fibers typically with ytterbium, neodymium, erbium, thulium, holmium and other dopings such as aluminum and phosphorus to adjust the refractive index of the fiber core.
  • active glass fibers typically with ytterbium, neodymium, erbium, thulium, holmium and other dopings such as aluminum and phosphorus to adjust the refractive index of the fiber core.
  • problems can arise during welding or splicing, for example due to the different glass melting temperatures.
  • polarization-maintaining glass fibers it must also be ensured during welding that the stress cores in the glass fiber are well aligned and welded to one another.
  • This problem can also occur with continuously operating fiber amplifiers, for example with the optical amplification of spectrally narrow-band laser sources, which can generate stimulated Brillioun scattering on long fiber optic stretches and thus destabilize the fiber amplifier operation and reduce the amplifier output power.
  • the conflict of objectives between the use of passive glass fibers and active glass fibers should be at least partially resolved or at least at least be reduced.
  • At least an alternative to known fiber amplifiers or fiber lasers should be created.
  • the present invention relates to a fiber amplifier or a fiber laser with at least one active glass fiber with at least one core for guiding at least one signal light radiation (of the fiber amplifier) or a cavity-internal laser radiation (of the fiber laser) and with at least one jacket for guiding at least one first pump light radiation, with at least a first pumping light source which is designed to generate the first pumping light radiation, the first pumping light source preferably having at least one first diode laser, particularly preferably a plurality of first diode lasers, and with at least one pumping light coupler which is connected and configured with the first pumping light source, in order to receive the first pump light radiation from the first pump light source, wherein the pump light coupler is connected directly to the active glass fiber and is designed to direct the first pump light radiation at least into the cladding of the active glass fiber to be coupled.
  • the pump light trap is thus also connected directly to the active glass fiber, so that any connection points or splice points between the pump light coupler and the pump light trap as well as within the pump light coupler and the pump light trap can be avoided.
  • the pumping light coupler and the pumping light traps are produced directly and immediately on the continuous, one-piece active glass fiber.
  • At least the core of the active glass fiber extends away from the pump light coupler, at least in sections, away from the pump light trap and the pump light trap is designed to allow a sufficient proportion of the first pump light radiation to pass through as non-absorbed first pump light radiation so that the optical properties of the signal light radiation or the resonator-internal laser radiation are retained at least essentially away from the pump light trap, at least in sections.
  • At least the core of the active glass fiber and preferably the active glass fiber as a whole extends from the pump light coupler to the pump light trap and also beyond this, so that the properties and advantages of active glass fibers can also be used beyond the pump light trap.
  • further connection points beyond the pump light trap can be avoided or their number can at least be reduced and the corresponding disadvantages of connection points thus avoided.
  • the pump light trap In order to avoid or at least reduce the disadvantages of active glass fibers described above, which have no pump light radiation in the fiber cladding, the pump light trap, contrary to its usual purpose, is designed in such a way that the pump light trap allows part of the first pump light radiation in the fiber cladding to pass through and not dissipate . This can be done, for example, by appropriately designing depressions at least in the cladding of the active glass fiber within the pump light trap. The portion of the first pump light radiation that is let through by the pump light trap can be selected depending on the specific design of the fiber amplifier or the fiber laser so that the disadvantages described above with an active glass fiber without pump light in the fiber cladding can be avoided.
  • At least the core of the active glass fiber extends away from the pump light coupler beyond the pump light trap, at least in sections, and the pump light trap is designed, at least 10% of the first pump light radiation not absorbed in the active glass fiber as non- to let through absorbed first pump light radiation.
  • the remaining first pump light radiation not absorbed in the active glass fiber is picked up by the pump light trap.
  • the properties and advantages described above can be achieved.
  • the fiber amplifier has at least one signal light radiation input which is connected directly to the active glass fiber and is designed to receive the signal light radiation as incoming signal light radiation from outside the fiber amplifier and at least essentially directly at least into the core of the active glass fiber to be coupled, where at least the core of the active glass fiber, preferably the active glass fiber, between the signal light radiation input, the pump light coupler and the pump light trap is continuously formed in one piece.
  • the signal light radiation input can in particular be an open end of the active glass fiber.
  • the properties and advantages of active glass fibers described above can be used over the entire route from the signal light radiation input of the fiber amplifier via the pump light coupler to the pump light trap in the case of the same direction of propagation of the first pump light radiation and the incoming signal light radiation or via the pump light trap to towards the pump light coupler in the case of the opposite direction of propagation of the first pump light radiation and the incoming signal light radiation.
  • the disadvantages that can result from connection points or splice points between passive glass fibers and active glass fibers can also be avoided.
  • the fiber amplifier or the fiber laser has at least one signal light radiation output, which is directly connected to the active glass fiber and is designed to receive the signal light radiation as amplified signal light radiation or as a decoupled signal light radiation or to receive the laser radiation inside the resonator and to the outside of the fiber amplifier or the fiber laser, at least the core of the active glass fiber, preferably the active glass fiber, between the pump light coupler, the pump light trap and the signal light radiation output is formed continuously in one piece, the signal light radiation output preferably an optical lens, an optical window with anti-reflective coating or a passive feeder fiber.
  • the signal light radiation output can in particular be an open end of the active glass fiber.
  • the signal light radiation output can preferably be formed by an individual component such as an optical lens, an optical window with an anti-reflection coating or a passive feed glass fiber, which can be connected to the active glass fiber by means of a splice.
  • the properties and advantages of active glass fibers described above can be used over the entire route from the pump light coupler to the pump light trap to the signal light radiation output or until shortly before in the case of the same direction of propagation of the first pump light radiation and the coupled out signal light radiation or from the Pump light trap via the pump light coupler up to the signal light radiation output or until shortly before it in the case of the opposite direction of propagation of the first pump light radiation and the decoupled signal light radiation.
  • the disadvantages can be avoided or reduced, which can arise from connection points or splice points between passive glass fiber and active glass fiber.
  • the fiber laser has at least one highly reflective optical element, preferably at least one highly reflective fiber Bragg grating, which is connected directly to the active glass fiber and is designed to receive and reflect the laser radiation inside the cavity, at least the core of the active glass fiber, preferably the active glass fiber, between the pump light coupler, the pump light trap and the highly reflective optical element, between the pump light trap and the highly reflective optical element or between the pump light coupler, the pump light trap and the highly reflective optical element Element is formed in one piece throughout.
  • the properties and advantages of active glass fibers described above can be used in the fiber laser over the entire distance of a corre sponding section or over the entire length of the fiber laser.
  • the disadvantages that can result from connection points or splice points between passive glass fibers and active glass fibers can also be avoided.
  • the fiber laser has at least one low-reflecting optical element, preferably at least one low-reflecting fiber Bragg grating, which is connected directly to the active glass fiber and designed to receive and partially reflect the laser radiation inside the resonator partially let through, with at least the core of the active glass fiber, preferably the active glass fiber, between the pumping light coupler, the pumping light trap and the low reflecting optical element, between the pumping light trap and the low reflecting optical element or between the pumping light coupler, the pumping light trap and the low reflecting optical element is formed in one piece throughout.
  • the properties and advantages of active glass fibers described above can be used in the fiber laser over the entire route of a corresponding section or over the entire length of the fiber laser. It is also possible to avoid the disadvantages that can arise from connection points or splice points between passive glass fibers and active glass fibers.
  • the active glass fiber is wound up in sections, preferably between the pump light coupler and the pump light trap.
  • the pump light coupler is designed to couple the first pump light radiation in the same direction of propagation as the signal light radiation directly at least into the one of the active glass fiber. In this way, an arrangement can be created which can be referred to as “forward pumping”, as described at the outset.
  • the pump light coupler is designed to couple the first pump light radiation in the opposite direction of propagation to the signal light radiation directly at least into the cladding of the active glass fiber. This makes it possible to create an arrangement which can be referred to as “backward pumping”, as described at the outset.
  • the fiber amplifier or the fiber laser has at least one second pump light source which is designed to generate a second pump light radiation
  • the pump light coupler also being connected to the second pump light source and designed to supply the second pump light radiation from the second pump light source
  • the pump light coupler is also designed to couple the second pump light radiation opposite to the direction of propagation of the first pump light radiation directly at least into the cladding of the active glass fiber
  • the second pump light source preferably at least one second diode laser, particularly preferably a plurality of second diode lasers , having.
  • At least the core of the active glass fiber extends away from the pump light trap, at least in sections, away from the pump light coupler and the second pump light source is designed to generate the second pump light radiation in such a way that the optical properties of the signal light radiation or the laser radiation inside the resonator is retained at least substantially away from the pump light coupler, at least in sections.
  • the corresponding previously described properties of the first pump light radiation can also be implemented by means of the second pump light radiation.
  • the present invention also relates to a laser system with at least one fiber amplifier and / or with at least one fiber laser as described above.
  • a fiber amplifier according to the invention and / or a fiber laser according to the invention can be implemented and used in a laser system.
  • Such laser systems can be any types of devices or applications in which we- At least one fiber amplifier according to the invention and / or at least one fiber laser according to the invention can be used.
  • the present invention also relates to a method for manufacturing a fiber amplifier or a fiber laser as described above, which is characterized in that the manufacture of at least the pump light coupler and the pump light trap, preferably also the signal light radiation input and / or the signal light radiation output, is carried out directly on the active glass fiber laser-based manufacturing technology, preferably by means of a CO 2 laser or by means of a CO laser, takes place, the production preferably comprising the steps of drawing, welding and / or removing the active glass fiber.
  • the pump light coupler and the pump light trap can be formed directly on the active glass fiber by laser machining, with additional elements of the pump light coupler and / or the pump light trap such as a housing and the like being able to be added in additional manufacturing steps.
  • At least the formation of the active glass fibers in order to be able to be used as a pump light coupler or as a pump light trap takes place by means of a laser beam, which is preferably from a CO 2 laser with typically wavelengths between approx. 9 pm and approx. 11 pm or a CO laser with typically wavelengths of about 5 pm can be generated.
  • the laser beam can be flexibly adapted for each production step of the respective individual components with regard to its output power as well as the temporal and spatial irradiation of the respective process zone of the active glass fiber with the appropriate control and regulation technology.
  • the corresponding laser system can be used as a manufacturing device for the automatic production of all individual components of a fiber amplifier according to the invention and / or a fiber laser according to the invention. This can simplify and / or accelerate the production accordingly, whereby the manufacturing costs compared to known manufacturing processes can be reduced. It can also increase the quality of the manufactured products and / or reduce production errors.
  • FIGS. 1 to 4 are schematic representations of various exemplary embodiments of fiber amplifiers according to the invention.
  • FIGS. 5 to 18 are schematic representations of various exemplary embodiments of fiber lasers according to the invention.
  • FIG. 1 shows a schematic representation of a fiber amplifier 1 according to the invention in accordance with a first exemplary embodiment.
  • the fiber amplifier 1 has in its middle area a coiled active glass fiber 11, to which according to the invention several individual components are directly connected in one piece, which up to now have been made as separate individual components with passive glass fibers and by means of welds or splices with one another and / or with the active one Glasfa ser 11 are integrally connected in one piece.
  • An incoming signal light radiation A is coupled into the fiber amplifier 1 as incoming laser radiation A by means of a signal light radiation input 15 of the fiber amplifier 1, which can also be referred to as a fiber connector 15.
  • the signal light radiation input 15 of the fiber amplifier 1 is designed as an open end of the active glass fiber 11.
  • the incoming laser radiation A is generated outside the fiber amplifier 1 by a signal light source 13 in the form of a laser beam source 13.
  • the signal light radiation input 15 is connected directly to the active glass fiber 11, so that the incoming laser radiation A is coupled via the signal light radiation input 15 directly into the active glass fiber 11 or into its core.
  • the signal light radiation input 15 is followed by a pump light trap 17 and this is followed by the coiled section of the active glass fiber 11, so that the active glass fiber 11 is consistently one-piece and free of interruption or connection points from the signal light radiation input 15 to the coiled central one Section runs.
  • a pump light coupler 16 which is also connected directly to the active glass fiber 11, which is made continuously in one piece, adjoins the spooled-up section of the active glass fiber 11 to the right. From the right, a first pump light radiation C, which is generated by several first laser diodes 14a, which together form a first pump light source 14a, is coupled into the active glass fiber 11 in the opposite direction of propagation to the incoming laser radiation A.
  • Such an arrangement or alignment of the first pump light source 14a can be referred to as "backward pumping".
  • the incoming laser radiation A is amplified by means of the first pump light radiation C over the entire length of the active glass fiber 11 from the pump light coupler 16 to the pump light trap 17 after leaving the pump light coupler 16 to the right, this can be referred to as amplified signal light radiation B or as amplified laser radiation B.
  • the active glass fiber 11 extends further up to a signal light radiation output 18, which can also be referred to as fiber exit optics 18.
  • the amplified laser radiation B is coupled out to the outside of the fiber amplifier 1 via the signal light radiation output 18.
  • the signal light radiation output 18 can be used as the open end of the active glass fiber 18 but also as a spliced individual component in the form of an optical lens 18, an optical window 18 with anti- Reflective coating or a passive feed glass fiber 18 may be formed.
  • the incoming laser radiation A can be amplified to form the amplified laser radiation B and made available in this form by the fiber amplifier 1.
  • the pump light trap 17 is designed in such a way that a sufficient proportion of the first pump light radiation C is allowed to pass through as non-absorbed first pump light radiation C 'to the left to the signal light radiation input 15, so that the optical properties of the incoming laser radiation A are at least substantially retained.
  • a sufficient amount of non-absorbed first pump light radiation C ' is guided between the pump light trap 17 and the Signalichtstrah treatment input 15 in the cladding of the active glass fiber 11, so that an undesirable absorption behavior of the active glass fiber 11 in this area is at least reduced or even completely avoided which can be.
  • Such a fiber amplifier 1 according to the invention is formed at least with regard to the pump light coupler 16 and the pump light trap 17 directly on the continuously extending active glass fiber 1 with means of laser-based manufacturing technology such as in particular by means of a CO 2 laser or a CO laser.
  • those processing steps, such as drawing and ablation, which are required for manufacturing the pump light coupler 16 or the pump light trap 17, are carried out directly on the active glass fiber 1 by means of a laser beam. Further manufacturing steps of the pump light coupler 16 or the pump light trap 17 can then be carried out on these sections of the active glass fiber 1.
  • the connection of the signal light radiation input 15 and / or the signal light radiation output 18 as a (each) passive individual component can also take place by means of a laser beam from the same source in the form of welding or splicing.
  • FIG. 2 shows a schematic representation of a fiber amplifier 1 according to the invention in accordance with a second exemplary embodiment.
  • a second pump light source 14b in the form of at least one second diode laser 14b is provided, which generates a second pump light radiation D and is coupled into the active glass fiber 11 by means of the pump light coupler 16 opposite to the direction of propagation of the first pump light radiation C.
  • an undesired absorption behavior of the active glass fiber 11 can at least be reduced or even completely avoided by means of the second pump light radiation D in the area of the active glass fiber 11 between the pump light coupler 16 and the signal light radiation output 18.
  • FIG. 3 shows a schematic representation of a fiber amplifier 1 according to the invention in accordance with a third exemplary embodiment.
  • the fiber amplifier 1 according to the third exemplary embodiment corresponds to the fiber amplifier 1 according to the first exemplary embodiment in FIG. Section of the active glass fiber 11 and the pump light trap 17 is arranged accordingly to the right thereof.
  • Such an arrangement or alignment of the first pump light source 14a can be referred to as “forward pumping”.
  • FIG. 4 shows a schematic representation of a fiber amplifier 1 according to the invention in accordance with a fourth exemplary embodiment.
  • the fiber amplifier 1 according to the fourth exemplary embodiment corresponds to the fiber amplifier 1 according to the third exemplary embodiment in FIG. 3, with the difference that in this case the second pump light source 14b according to the second exemplary embodiment in FIG. 2 is also provided.
  • FIG. 5 shows a schematic representation of a fiber laser 1 according to the invention in accordance with a first exemplary embodiment.
  • the structure of the fiber laser 1 in accordance with the first exemplary embodiment in FIG. 5 basically corresponds to the structure of the fiber amplifier 1 in accordance with the first exemplary embodiment in FIG. 1.
  • a highly reflective optical element 19a in the form of a highly reflective fiber Bragg grating 19a is arranged directly on the active glass fiber 11 on the left of the pump light trap 17 instead of the signal light radiation input 15.
  • a resonator-internal laser radiation E can pass through the pump light trap 17 unaffected in both directions and be reflected back to the pump light trap 17 on the highly reflective optical element 19a.
  • a low-rig reflective optical element 19b in the form of a low-reflective fiber Bragg grating 19b is arranged directly on the active glass fiber 11 between the pump light coupler 16 and the signal light radiation output 18.
  • the low-reflecting optical element 19b only reflects part of the laser radiation E inside the cavity to the pump light coupler 16 and allows the remaining part of the laser radiation E inside the cavity as laser radiation F to be coupled out to the signal light radiation output 18, in order to allow it to outside of the fiber laser 1 as coupled out laser radiation F. leaving.
  • the active glass fiber 11 extends from the highly reflective optical element 19a to the signal light radiation output 18 or, if a single component is used as the signal light radiation output 18, until shortly before it in one piece. In this case, too, splice points and their disadvantages can be avoided or kept as low as possible.
  • FIG. 6 shows a schematic representation of a fiber laser 1 according to the invention in accordance with a second exemplary embodiment.
  • the structure of the fiber laser 1 in accordance with the second exemplary embodiment in FIG. 6 corresponds to the structure of the fiber laser 1 in accordance with the first exemplary embodiment in FIG. 5.
  • the second pump light source 14b is also present here, as described in the second exemplary embodiment of the fiber amplifier 1 according to FIG.
  • the fiber laser 1 according to the invention can also be produced by means of laser-based manufacturing technology, as described above with regard to the fiber amplifier 1 according to the invention.
  • FIG. 7 shows a schematic representation of a fiber laser 1 according to the invention in accordance with a third exemplary embodiment.
  • the structure of the fiber laser 1 according to the third exemplary embodiment in FIG. 7 corresponds to the structure of the fiber laser 1 according to the first exemplary embodiment in FIG active glass fiber 11 is arranged.
  • FIG. 8 shows a schematic representation of a fiber laser 1 according to the invention in accordance with a fourth exemplary embodiment.
  • the structure of the fiber laser 1 in accordance with the fourth exemplary embodiment in FIG. 8 corresponds to the structure of the fiber laser 1 in accordance with the third exemplary embodiment in FIG of Figure 2 described.
  • FIG. 9 shows a schematic representation of a fiber laser 1 according to the invention in accordance with a fifth exemplary embodiment.
  • the structure of the fiber laser 1 according to the fifth embodiment of FIG. 9 corresponds to the structure of the fiber laser 1 according to the first embodiment of FIG is arranged in front of the pump light trap 17. Since the active glass fiber 11 in this case to the left of the pump light trap 17 no longer has any resonator-internal laser radiation E, the pump light trap 17 can completely remove the first pump light radiation C from the cladding of the active glass fiber 11.
  • FIG. 10 shows a schematic representation of a fiber laser 1 according to the invention in accordance with a sixth exemplary embodiment.
  • the structure of the fiber laser 1 according to the sixth embodiment of FIG. 10 corresponds to the structure of the fiber laser 1 according to the fifth embodiment of FIG Figure 2 described.
  • FIG. 11 shows a schematic representation of a fiber laser 1 according to the invention in accordance with a seventh exemplary embodiment.
  • the structure of the fiber laser 1 according to the seventh embodiment of FIG. 11 corresponds to the structure of the fiber laser 1 according to the first embodiment of FIG in front of the pump light trap 17 as well as the low-reflecting optical element 19b to the left of the pump light coupler 16 and in front of the spooled-up Section of the active glass fiber 11 is arranged, as described in each case in the third exemplary embodiment in FIG. 7 and in the fifth exemplary embodiment in FIG. In this case too, the active glass fiber 11 to the left of the pump light trap 17 no longer has any resonator-internal laser radiation E and the pump light trap 17 can completely remove the first pump light radiation C from the cladding of the active glass fiber 11.
  • FIG. 12 shows a schematic representation of a fiber laser 1 according to the invention in accordance with an eighth exemplary embodiment.
  • the structure of the fiber laser 1 according to the eighth embodiment of FIG. 12 corresponds to the structure of the fiber laser 1 according to the seventh embodiment of FIG Figure 2 described.
  • FIGS. 13 to 18 show ninth to fourteenth exemplary embodiments of a fiber laser 1 according to the invention, which correspond to the first to fifth and seventh exemplary embodiments of FIGS Pumping "are called.
  • Fiber exit optics 18 signal light radiation output; Fiber exit optics; optical lens, optical window with anti-reflection coating; passive feeder fiber

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)

Abstract

L'invention concerne un amplificateur à fibre (1) ou un laser à fibre (1) comprenant une fibre de verre (11) active qui comporte un noyau pour guider un rayonnement de signal lumineux (A, B, F) ou un rayonnement laser à l'intérieur du résonateur, ainsi qu'une gaine pour guider au moins un rayonnement de lumière de pompage (C, C'), une première source de lumière de pompage (14a) pour générer un premier rayonnement de lumière de pompage (C), un coupleur de lumière de pompage (16) conçu pour injecter le premier rayonnement de lumière de pompage (C) directement au moins dans la gaine de la fibre de verre (11) active, et un piège à lumière de pompage (17) conçu pour évacuer au moins partiellement le premier rayonnement de lumière de pompage (C) au moins hors de la gaine de la fibre de verre (11) active. Le coupleur de lumière de pompage (16) et le piège à lumière de pompage (17) sont directement produits sur la fibre de verre active conçue d'un seul tenant en continu, de sorte qu'entre le coupleur de lumière de pompage (16) et le piège à lumière de pompage (17) ainsi que dans le coupleur de lumière de pompage (16) et le piège à lumière de pompage (17), tous les points de liaison ou toutes les épissures puissent être évités.
EP21733391.3A 2020-06-11 2021-06-09 Amplificateur à fibre ou laser à fibre Pending EP4165737A1 (fr)

Applications Claiming Priority (2)

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DE102020115555.7A DE102020115555A1 (de) 2020-06-11 2020-06-11 Faserverstärker oder Faserlaser
PCT/EP2021/065527 WO2021250127A1 (fr) 2020-06-11 2021-06-09 Amplificateur à fibre ou laser à fibre

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EP4165737A1 true EP4165737A1 (fr) 2023-04-19

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US8462426B1 (en) 2009-12-03 2013-06-11 The United States Of America As Represented By The Secretary Of The Air Force Scalable monolithic single frequency fiber amplifier
US8903214B2 (en) 2010-06-25 2014-12-02 Nkt Photonics A/S Large core area single mode optical fiber
WO2014105757A1 (fr) 2012-12-31 2014-07-03 Nlight Photonics Corporation Amplificateur à fibres lma tout en fibres à faible pointage dynamique de forte puissance
GB2511923B (en) * 2013-01-28 2018-10-03 Lumentum Operations Llc A cladding light stripper and method of manufacturing
US10277002B2 (en) 2016-12-05 2019-04-30 Bae Systems Information And Electronic Systems Integrations Inc. Monolithic integrated seed and high power pump source
US10530114B2 (en) 2017-08-31 2020-01-07 United States Of America As Represented By The Administrator Of Nasa Polarization maintaining, large mode area (PMVLMA) erbium-doped optical fiber and amplifier

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WO2021250127A1 (fr) 2021-12-16

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