Laser beam amplification device
By using a dual-tilt design and optical compensation components, the problems of insufficient cooling and time contrast in laser amplification devices are solved, achieving efficient beam amplification and low loss, thus improving the performance and reliability of the equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- THALES SA
- Filing Date
- 2021-12-13
- Publication Date
- 2026-06-05
Smart Images
Figure CN116724471B_ABST
Abstract
Description
[0001] This invention relates to a device for amplifying multi-wavelength laser beams.
[0002] The field of this invention is the field of solid-state laser sources for scientific, industrial, medical, and military applications. More specifically, the invention is advantageously applicable to active laser dielectric materials (e.g., crystal) having a small thickness along the propagation axis of the laser beam relative to its aperture, typically less than 1:3.
[0003] Pumped laser technology has seen significant development in recent years, and pulsed laser sources that can now provide an average pump power of at least one hundred watts are now available.
[0004] However, a certain number of designs cannot match the next generation of pump lasers that seek high energy and high average power (higher repetition rate).
[0005] At the current technological level, different schemes are used to study the shape factor of active laser media to extract thermal energy, typically amplifier fibers, ultrathin disks, slats, and so-called thick disks.
[0006] Thick disk approaches are well-suited for specific active laser media such as amorphous materials (e.g., glass), transparent ceramics, or crystals such as Ti:SA (titanium: sapphire). Due to the material's larger amplification spectrum, this approach enables high energy levels, high average power, and short pulse durations.
[0007] In thick-disk technology, the active laser medium is cooled via its rear surface. Cooling is then achieved through a fluid or solid, which can be liquid or gas. This rear-surface cooling increases the heat transfer surface area. Furthermore, a thermal gradient can be generated along the direction of laser propagation through the active laser medium in the same manner, and this is also used to achieve higher heat extraction. The refractive index change associated with temperature variations in the active laser medium is a gradient oriented primarily along the same direction as the laser beam propagation.
[0008] However, rear-surface cooled laser amplification devices cause the beam to be geometrically reflected due to the reflective rear surface of the active laser medium (e.g., crystal). The output facet of the active laser medium is therefore identical to the input facet, meaning that spurious pulses are detected before the main pulse (attributed to spurious reflections on the front facet), thus reducing the pulse temporal contrast. Temporal contrast is defined as the ratio between the intensity of the main pulse and the intensity of the bottom of that pulse and / or any spurious pulses.
[0009] To avoid this reduction, a method for altering the air / crystal interface to separate the master pulse and the spurious pulse is known from patent EP2915226B. For this purpose, the front face of the active laser medium is tilted at a non-zero angle relative to its rear face. Thus, after propagation through the active laser medium, the spurious reflection is spatially separated from the master pulse, and the temporal contrast is no longer reduced by the spurious reflection.
[0010] For short pulses (with a broad spectrum), the angle produces a prism effect, which is compensated for by a compensating prism positioned along the beam path, as described in EP2915226B. Therefore, when traversing an active laser medium multiple times, multiple prisms must be used in the amplification device.
[0011] In addition to the financial impact, the use of multiple optical components for transmission results in optical losses and potential failures (damage renders the laser unusable and incurs the cost of repair parts and repositioning labor).
[0012] Therefore, there is a need for an amplification device that maintains satisfactory cooling and time contrast while minimizing optical loss.
[0013] Therefore, the subject of this invention is an apparatus for amplifying multi-wavelength laser beams, the apparatus comprising:
[0014] a. A first solid active laser medium having a first refractive index, the first active laser medium having at least two planar surfaces, including a front surface for receiving a beam to be amplified, referred to as an incident beam, and a rear surface for reflecting, the front surface being inclined at a first non-zero tilt angle relative to the rear surface, the rear surface being used for cooling; and
[0015] b. A second solid-state active laser medium having a second refractive index, the second active laser medium having at least two planar faces, including a front face for receiving a beam reflected by the rear face of a first active laser medium and refracted by the front face, and a reflecting rear face, the front face being tilted relative to the rear face at a second non-zero tilt angle, the rear face being used for cooling, the second active laser medium being disposed along the path of the beam reflected by the rear face of the first active laser medium and refracted by the front face, the first tilt angle, the second tilt angle, and the orientation of the second active laser medium such that sub-beams of each wavelength forming the output beam of the second active laser medium are parallel to each other at the output portion of the second active laser medium.
[0016] According to another advantageous aspect of the invention, the device includes one or more of the following features, either individually or in combination of all technically feasible options:
[0017] - The front surface of the first active laser medium is perpendicular to the axis Oz. The first tilt angle forms angle β1' on the plane xOz and angle β1” on the plane yOz. The second tilt angle forms angle β2' on the plane xOz and angle β2” on the plane yOz, satisfying the following conditions:
[0018] and
[0019] -The second active laser medium is configured relative to the first active laser medium such that:
[0020] a. The front surface of the second active laser medium is parallel to the front surface of the first active laser medium;
[0021] and
[0022] b. The rear surface of the second active laser medium is parallel to the rear surface of the first active laser medium;
[0023] - The beam at the output of the second active laser medium has a diameter that is wider than that of the incident beam. The amplification device includes an optical compensation component for compensating for the widening of the beam at the output of the second active laser medium, such that the beam at the output of the amplification device has a diameter that is substantially equal to that of the incident beam.
[0024] -Optical compensation components include:
[0025] a. A third solid active laser medium having a third refractive index, the third active laser medium having at least two planar faces, including a front face for receiving a beam from the output portion of a second active laser medium and a reflective rear face, the front face being tilted at a third non-zero tilt angle relative to the rear face, and the rear face being used for cooling.
[0026] b. A fourth solid-state active laser medium having a fourth refractive index, the fourth active laser medium having at least two planar faces, including a front face for receiving a beam reflected by the rear face of a third active laser medium and refracted by the front face, and a reflecting rear face, the front face being inclined at a fourth non-zero tilt angle relative to the rear face, the rear face being used for cooling, the fourth active laser medium being disposed along the path of the beam reflected by the rear face of the third active laser medium and refracted by the front face,
[0027] The third tilt angle, the fourth tilt angle, the orientation of the third active laser medium, and the orientation of the fourth active laser medium make the diameter of the output beam of the fourth active laser medium substantially equal to the diameter of the incident beam, and make the sub-beams of each wavelength forming the output beam parallel to each other at the output part of the fourth active laser medium.
[0028] - The front surface of the third active laser medium is perpendicular to the axis Oz. The third tilt angle forms an angle β3' on the plane xOz and an angle β3' on the plane yOz. The third tilt angle forms an angle β3' on the plane xOz and an angle β3' on the plane yOz, satisfying the following conditions:
[0029] and
[0030] - The third active laser medium is configured relative to the fourth active laser medium such that:
[0031] a. The front surface of the third active laser medium is parallel to the front surface of the fourth active laser medium;
[0032] and
[0033] b. The rear face of the third active laser medium is parallel to the rear face of the fourth active laser medium;
[0034] -The first active laser medium, the second active laser medium, the third active laser medium, and the fourth active laser medium are the same;
[0035] - The first medium, the second medium, the third medium and the fourth medium form a so-called reference amplification unit. The light beam reflected from the rear part of the fourth medium and refracted from the front part forms the output beam of the reference amplification unit. The amplification device includes one or more consecutive amplification units identical to the reference amplification unit. Each amplification unit is configured to receive the output beam of the preceding amplification unit as an input beam.
[0036] - The optical compensation component includes at least one mirror, which is configured to superimpose the output beam of the amplification device onto the incident beam;
[0037] - The front part of the active laser medium is used to receive the incident beam and reflect a beam known as the first spurious beam from the incident beam. The first optical return unit is located outside the path of the first spurious beam.
[0038] - The front portion of the active laser medium is used to receive the beam from the output portion of the first active laser medium and reflect a beam called the second spoofing beam from the received beam; the third active laser medium is disposed outside the path of the first spoofing beam; and
[0039] - The front part of the third active laser medium is used to receive the beam from the output part of the second active laser medium and reflect the beam from the received beam into a beam called the third spoofing beam. The fourth active laser medium is disposed outside the path of the third spoofing beam.
[0040] Other features and advantages of the invention will become apparent from the following description of embodiments thereof, which is given by way of limiting example only and with reference to the accompanying drawings:
[0041] Figure 1 This is a schematic plan view showing the enlargement device according to the first embodiment;
[0042] Figure 2 This is a schematic plan view showing an enlarged device according to a usage example of the second embodiment;
[0043] Figure 3 This is a schematic plan view showing an enlarged device according to another usage example of the second embodiment; and
[0044] Figure 4 This is a schematic plan view showing the enlargement device according to the third embodiment. Detailed Implementation
[0045] In the following description, a propagation direction z is defined, which is represented by the axis z in the figures and corresponds to the propagation direction of the laser beam. A first transverse direction is defined, which is perpendicular to the propagation direction and is represented by the axis x in the figures, such that the plane (xOz) corresponds to the top view of the magnifying device 10. A second transverse direction y is also defined, which is perpendicular to the propagation direction z and the first transverse direction x. The second transverse direction y is represented by the axis y in the figures and such that the plane (yOz) corresponds to the side view of the magnifying device 10.
[0046] In the following description, the term "spatial dispersion" refers to the spatial dispersion of a light beam caused by the variation of the offset angle with respect to the wavelength in the optical surface. The term "lateral dispersion" refers to the widening of the beam diameter with respect to wavelength after passing through two parallel optical surfaces (a plate with parallel faces) at the interface (pupil shift).
[0047] Figure 1 The first embodiment of the amplification device 10 is shown in the figure.
[0048] The amplification device 10 is configured to amplify a laser beam, particularly a multi-wavelength pulsed laser beam. The beam to be amplified is, for example, an infrared beam.
[0049] The beam to be amplified has, for example, an average power greater than 10 watts (W).
[0050] The amplification device 10 according to the first embodiment includes at least one active laser medium M1 and at least one second active laser medium M2.
[0051] The first medium M1 is a solid medium. The first medium M1 is, for example, crystal, such as titanium-doped sapphire or Yb:YAG, Yb:CaF2 or polymer, ceramic or glass or any other solid material.
[0052] The first medium M1 has a first refractive index n1.
[0053] Preferably, the following relationship was verified:
[0054]
[0055] Where v1 is the reciprocal dispersion coefficient of the first active laser medium M1. The above configuration is used to maintain the beam F at the output of the amplification device 10. S Multi-wavelength characteristics.
[0056] The first medium M1 has a component for receiving what is called the incident beam F. I The face of at least two planes of the front face 20 and the rear face 22 of the beam to be magnified.
[0057] The front portion 20 is inclined at a non-zero angle β1 relative to the rear portion 22. The first medium M1 has a front portion and a rear portion inscribed within a trapezoidal base. Figure 1 A disk-shaped prism with a triangular base. In the following text, β1' is the projection of the inclination angle β1 onto the plane (xOz) and β1” is the projection of the inclination angle β1 onto the plane (yOz).
[0058] exist Figure 1 In the specific example shown, angle β1' equals tilt angle β1 and angle β1” is zero. The base of the first medium M1 is thus contained in a plane parallel to the plane (xOz). As will be described below, the above construction can be used to remove spurious pulses in the plane (xOz). However, this construction is given as an example because angles β1' and β1” can both be non-zero.
[0059] The front part 20 of the first medium M1 is used to receive the incident light beam F. I And the reflection is called the first deceptive beam F. P1 A convincing beam and known as the first available beam F R1 The beam of light is refracted after being reflected by the rear face 22.
[0060] Advantageously, the front part 20 is treated with anti-reflective coating.
[0061] The rear portion 22 of the first active laser medium M1 is used for reflection after passing through the front portion 20 of the first active laser medium M1 to form a first usable beam F. R1 .
[0062] The rear section 22 is used for cooling, for example, by a cooling device included in the amplification device 10. Cooling is... Figure 1 The middle part is indicated by the arrow attached to the back face 22.
[0063] The second active laser medium M2 is a solid medium. The second medium M2 is, for example, crystal, such as titanium-doped sapphire or Yb:YAG, Yb:CaF2 or polymer, ceramic or glass or any other solid material.
[0064] The second medium M2 has a second refractive index n2.
[0065] Preferably, the following relationship was verified:
[0066]
[0067] Where ν2 is the reciprocal dispersion coefficient of the second active laser medium M2. The above configuration is used to maintain the beam F at the output of the amplification device 10. S Multi-wavelength characteristics.
[0068] Medium M2 has a portion for receiving what is called the incident beam F I The face of at least two planes of the front face 20 and the rear face 22 of the beam to be magnified.
[0069] The front portion 20 is inclined at a non-zero angle β2 relative to the rear portion 22. Therefore, the second medium M2 has a front portion and a rear portion inscribed within a trapezoidal base. Figure 1 A disk-shaped prism with a triangular base. In the following text, β2' is the projection of the inclination angle β2 onto the plane (xOz) and β2” is the projection of the inclination angle β2 onto the plane (yOz).
[0070] exist Figure 1 In the specific example shown, angle β2' equals tilt angle β2 and angle β2” is zero. The base of the second medium M2 is therefore contained in a plane parallel to the plane (xOz). As will be described below, the above construction can be used to remove spurious pulses in the plane (xOz). However, this construction is given as an example because angles β2' and β2” can both be non-zero.
[0071] In a preferred embodiment, the second medium M2 is the same as the first medium M1. Therefore, n1 = n2 and β1 = β2. Advantageously, the first medium M1 and the second medium M2 are manufactured during the same manufacturing process.
[0072] Advantageously, the front part 20 is treated with anti-reflective coating.
[0073] The rear section 22 is used for cooling, for example, by a cooling device included in the amplification device 10. Cooling is... Figure 1The middle part is indicated by the arrow attached to the rear face 22.
[0074] The second active laser medium M2 is configured relative to the first medium M1 to be along the first available laser beam F. R1 The path. The first available beam F R1 This light is thus received on the front surface 20 of the second medium M2. Therefore, the front surface 20 of the second medium M2 is used to reflect what is called the second deception beam F. P2 The realistic beam (not shown in the attached image to avoid overloading the image) Figure 1 (as shown in the image) and in what is called the second available beam F R2 The available light beam is refracted after being reflected by the rear surface 22 of the second medium M2.
[0075] The first tilt angle β1, the second tilt angle β2, and the orientation of the second active laser medium M2 are selected such that the second usable output beam F forming the second active laser medium M2 is formed. R2 The sub-beams of each wavelength are parallel to each other at the output of the second active laser medium M2. Figure 1 In order to avoid overloading the attached diagram, only two sub-beams are shown. The second medium M2 is thus used to compensate for the spatial dispersion caused by the prism effect due to the tilt angle β1 between the front portion 20 and the rear portion 22 of the first medium M1.
[0076] Advantageously, the following conditions were verified:
[0077] and
[0078] Advantageously, the second active laser medium M2 is configured relative to the first active laser medium M1 such that:
[0079] - The front portion 20 of the second active laser medium M2 is parallel to the front portion 20 of the first active laser medium M1; and
[0080] - The rear face 22 of the second active laser medium M2 is parallel to the rear face 22 of the first active laser medium M1.
[0081] Therefore, if two media M1 and M2 are connected to each other without changing their respective orientations, an optical surface with parallel faces will be obtained.
[0082] Advantageously, the second active laser medium M2 is positioned in the first spoofing beam F P1 The outside of the path.
[0083] Preferably, the second medium M2 is configured to have a distance L from the first medium M1, such that the magnified beam ( Figure 1 The output beam F in S =FR2 ), Realistic Beam F P1 and incident beam F I Spatially separated. This separation is denoted by L, such that:
[0084] or
[0085] in:
[0086] Φ is the incident beam F I The diameter;
[0087] ·θ i It is the incident angle of the light beam incident on the front surface 20 of the first medium M1 in the plane (xOz);
[0088] · It is the incident angle of the light beam incident on the front surface 20 of the first medium M1 in the plane (yOz);
[0089] ·β′1 is the angle produced by the projection of the tilt angle β1 onto the plane (xOz);
[0090] •β″1 is the angle produced by the projection of the tilt angle β1 onto the plane (yOz); and
[0091] ·n1 is the optical index of the first medium M1.
[0092] The operation of the amplification device 10 according to the first embodiment will now be described.
[0093] Initially, the beam (pulse) F with a diameter of Φ to be amplified I With the incident angle θ in the plane (xOz) i Angle of incidence in the plane (yOz) It reaches the front part 20 of the active laser medium M.
[0094] A usable beam is reflected by the rear face 22, and a simulated beam F is reflected by the front face 20. P1 The spurious beam, also known as a spurious pulse, is deflected at the front part 20 to have an angle of 2θ in the plane (xOz). i And it has an angle in the plane (yOz). The amplified beam F in the active laser medium M1, also known as the master pulse. R1 At the output, it is deflected to have an angle of 2(θ) in the plane (xOz). i +β1′.(n1-1) and has an angle 2 in the plane (yOz). (n1-1).
[0095] Since the source is a multi-wavelength laser source, the angle β1′ formed by faces 20 and 22 in the plane (xOz) and the angle β″1 formed by faces 20 and 22 in the plane (yOz) produce a prism effect. Therefore, after passing through the first active laser medium M1, the light beam F refracted by the front face 20 and reflected by the rear face 22 of the first medium M1... R1 The wavelengths of the (available light beams) are separated at an angle.
[0096] Along the available beam F R1 The path is set in the available beam F R1 And the indistinguishable beam F P1 The second medium M2 after separation is used to correct spatial dispersion according to wavelength.
[0097] More specifically, in Figure 1 In the specific example shown, β1'=β2'=β and β1”=β2”=0, resulting in the entire propagation taking place in the plane (xOz).
[0098] It should be noted that at the output of the active laser medium M2, the amplified beam F R2 The spectral components form a light spot with a diameter of Φ+ΔΦ. It should be noted that ΔΦ includes the diameter increase due to the divergence of the beam during its second passage through the first active laser medium M1 and the subsequent divergence of the beam along the path between the output portion (front face 20) of the first medium M1 and the second medium M2. The output portion of the second active laser medium M2 has the same diameter Φ+ΔΦ. To maintain the multi-wavelength characteristics of the output beam, the amplified beam F... R2 The increase in diameter, ΔΦ, must be less than Φ. This is The situation at that time.
[0099] In fact,
[0100] And in hour This means that ΔΦ << Φ.
[0101] Thus, the amplification device 10 according to the first embodiment is used to compensate for the spatial dispersion caused by the tilt angle β of the first active laser medium M1 without generating additional losses. In fact, this compensation is achieved by using another active laser medium that does not generate losses but instead has a greater gain than a single thick disk.
[0102] The amplification device 10 according to the first embodiment is therefore used to minimize optical loss while maintaining satisfactory cooling and time contrast.
[0103] This amplification device 10 can also be used to share gain across multiple disks, which is advantageous for the heat load and lateral lasing of each disk.
[0104] According to the second embodiment, such as Figure 2 and Figure 3 As can be seen in the reference Figure 1 The same components as those in the amplification device 10 according to the first embodiment will not be repeated. Only the differences will be emphasized.
[0105] In the second embodiment, in addition to the components of the first amplification device 10, the amplification device 10 also includes an optical compensation component 30, which is used to compensate for the beam F at the output of the second active laser medium M2. R2 The broadening amount ΔΦ (the beam reflected by the rear part 22 and refracted by the front part 20) makes the beam F at the output of the amplification device 10... S With the incident beam F I The diameters Φ are essentially equal. The compensation device 30 is thus used to compensate for transverse dispersion.
[0106] like Figure 2 and Figure 3 As shown, the compensation optical component 30 includes a third active laser medium M3 and a fourth active laser medium M4.
[0107] The third medium M3 is a solid medium. The third medium M3 is, for example, crystal, such as titanium-doped sapphire or Yb:YAG, Yb:CaF2 or polymer, ceramic or glass or any other solid material.
[0108] The third medium M3 has a third refractive index n3.
[0109] Preferably, the following relationship was verified:
[0110]
[0111] Where ν3 is the reciprocal dispersion coefficient of the third active laser medium M3. The above configuration is used to maintain the beam F at the output of the amplification device 10. S Multi-wavelength characteristics.
[0112] The third medium M3 has a second usable beam F at the output section for receiving the second active laser medium M2. R2 The face has at least two planes, the front face 20 and the rear face 22.
[0113] The front portion 20 of the third medium M3 is inclined at a non-zero angle β3 relative to the rear portion 22 of the third medium M3. The third medium M3 thus has a front portion and a rear portion inscribed within a trapezoidal base ( Figure 2 and Figure 3A disk-shaped prism with a triangular base. In the following text, β3' is the projection of the inclination angle β3 onto the plane (xOz) and β3” is the projection of the inclination angle β3 onto the plane (yOz).
[0114] exist Figure 2 and Figure 3 In the specific example shown, angle β3' equals tilt angle β3 and angle β3” is zero. The base of the third medium M3 is therefore contained in a plane parallel to the plane (xOz). As will be described below, the above construction can be used to remove spurious pulses in the plane (xOz). However, this construction is given as an example because angles β3' and β3” can both be non-zero.
[0115] Advantageously, the following conditions were verified:
[0116] and
[0117] In a preferred embodiment, the third medium M3 is the same as the second medium M2 and the first medium M1. Therefore, n1 = n2 = n3 and β1 = β2 = β3. Advantageously, the first medium M1, the second medium M2, and the third medium M3 are manufactured during the same manufacturing process.
[0118] The front part 20 of the third medium M3 is used to receive the beam F from the output part of the second active laser medium M2. R2 And the reflection is called the deceptive beam F. P3 The realistic beam (not shown in the attached image to avoid overloading the image) Figure 2 and Figure 3 (as shown in the image) and in what is called the third available beam F R3 The beam of light is refracted after being reflected by the rear part 22 of the third medium M3.
[0119] The rear portion 22 of the third medium M3 is used for the beam F at the output portion of the second active laser medium M2. R2 After passing through the front portion 20 of the third medium M3, the beam is reflected to form a usable beam F. R3 .
[0120] The rear portion 22 of the third medium M3 is used for cooling by, for example, a cooling device included in the amplification device 10. Cooling in Figure 2 and Figure 3 The arrow in the middle is indicated by the arrow attached to the rear face 22 of the third medium M3.
[0121] Advantageously, the front surface 20 of the third medium is treated with anti-reflective coating.
[0122] The fourth medium M4 is a solid medium. The fourth medium M4 is, for example, crystal, such as titanium-doped sapphire or Yb:YAG, Yb:CaF2 or polymer, ceramic or glass or any other solid material.
[0123] The fourth medium M4 has a fourth refractive index n4.
[0124] Preferably, the following relationship was verified:
[0125]
[0126] Where ν4 is the reciprocal dispersion coefficient of the fourth active laser medium M4. The above configuration is used to maintain the beam F at the output of the amplification device 10. S Multi-wavelength characteristics.
[0127] The fourth medium M4 has a method for receiving what is called the incident beam F. I The face of at least two planes of the front face 20 and the rear face 22 of the beam to be magnified.
[0128] The front portion 20 is inclined at a non-zero angle β4 relative to the rear portion 22. The fourth medium M4 thus has the front and rear portions inscribed within a trapezoidal base. Figure 2 and Figure 3 A disk-shaped prism with a triangular base. In the following text, β4' is the projection of the inclination angle β4 onto the plane (xOz) and β4” is the projection of the inclination angle β4 onto the plane (yOz).
[0129] exist Figure 2 and Figure 3 In the specific example shown, angle β4' equals tilt angle β4 and angle β4” is zero. The base of the fourth medium M4 is thus contained in a plane parallel to the plane (xOz). As will be described below, the above construction can be used to remove spurious pulses in the plane (xOz). However, this construction is given as an example because angles β4' and β4” can both be non-zero.
[0130] In a preferred embodiment, the fourth medium M4 is the same as the third medium M3. Therefore, n3 = n4 and β3 = β4. Advantageously, the third medium M3 and the fourth medium M4 are manufactured during the same manufacturing process.
[0131] Advantageously, the front part 20 is treated with anti-reflective coating.
[0132] The rear section 22 is used for cooling, for example, by a cooling device included in the amplification device 10. Cooling is... Figure 2 and Figure 3 The middle part is indicated by the arrow attached to the rear face 22.
[0133] The fourth active laser medium M4 follows the beam F reflected by the rear part 22 of the third active laser medium M3 and refracted by the front part 20. R3 The path setting for the beam F. R3 Therefore, it is received by the front part 20 of the fourth medium M4. Thus, the front part 20 of the fourth medium M4 is used to reflect what is called the fourth deception beam F. P4 A convincingly realistic beam and available beam F R4 The beam is refracted after being reflected by the rear facet 22 of the fourth medium M4.
[0134] The third tilt angle β3, the fourth tilt angle β4, and the orientation of the third active laser medium M3, as well as the orientation of the fourth active laser medium M4, are selected such that the output beam F of the fourth active laser medium M4... R4 (corresponding to) Figure 2 and Figure 3 The output beam F of the amplification device 10 in the middle S The diameter of the incident beam F is approximately equal to that of the incident beam. I The diameter Φ, and to form the output beam F R4 The sub-beams of each wavelength are parallel to each other at the output of the fourth active laser medium M4. Therefore, the third medium M3 and the fourth medium M4 are used to compensate for the transverse dispersion of the beam.
[0135] Advantageously, the following conditions were verified:
[0136] and
[0137] Advantageously, the fourth active laser medium M4 is configured relative to the third active laser medium M3 such that:
[0138] - The front portion 20 of the third active laser medium M3 is parallel to the front portion 20 of the fourth active laser medium M4; and
[0139] - The rear face 22 of the third active laser medium M3 is parallel to the rear face 22 of the fourth active laser medium M4.
[0140] Therefore, if two media M3 and M4 are connected to each other without changing their respective orientations, an optical surface with parallel faces will be obtained.
[0141] Advantageously, the third active laser medium M3 is positioned in the second spoofing beam F P2 The outside of the path.
[0142] Advantageously, the fourth active laser medium M4 is positioned in the third spoofing beam F P3 The outside of the path.
[0143] Preferably, the first medium M1, the second medium M2, the third medium M3, and the fourth medium M4 are identical (same material, same angle) and are manufactured, for example, during the same manufacturing cycle or process. This particular case... Figure 2 As shown in the figure. In this particular case, there is an axis of symmetry As between the first medium and the second medium, and between the third medium and the fourth medium. The fourth medium M4 is thus symmetrical with respect to the axis of symmetry As to the first medium M1; and the third medium M3 is symmetrical with respect to the axis of symmetry As to the second medium M2.
[0144] Figure 3 Another example of the second embodiment is shown, in which the first medium M1 and the second medium M2 are identical, and the third medium M3 and the fourth medium M4 are identical but different from the first medium M1 and the second medium M2. In this case, there is no axis of symmetry between the first medium and the second medium, and between the third medium and the fourth medium.
[0145] During operation of the amplification device 10 according to the second embodiment, in addition to the operation described for the first embodiment, the available light beam F at the output of the second medium M2... R2 It is received on the front part 20 of the third medium M3, which produces the third spurious reflection F. P3 and the third available beam F R3 (Reflected on the rear portion 22 of the third medium M3 and refracted on the front portion 20). Third usable beam F R3 It is received on the front part 20 of the fourth medium M4, which produces the fourth spurious reflection F. P4 and the fourth available beam F R4 (Reflected on the rear portion 22 of the fourth medium M4 and refracted on the front portion 20). It should be noted that... Figure 2 and Figure 3 For clarity, the simulated reflection and F are not shown. P3 .
[0146] The construction of the third medium M3 and the fourth medium M4 relative to the first medium M1 and the second medium M2 can thus be used to compensate for the lateral dispersion of the amplified output beam of the amplification device 10.
[0147] Therefore, in addition to the advantages of the first embodiment, the amplification device 10 according to the second embodiment is also used to compensate for lateral dispersion caused during the crossing of the first active laser medium M1 without incurring additional losses. On the other hand, this compensation is performed by other active laser media that provide amplification gain.
[0148] Those skilled in the art will understand Figure 2 and Figure 3Only four active laser media are shown, but the advantages of the second embodiment can also be extended to a larger number of consecutive active laser media, where the number is a multiple of four (a multiple of two rather than four only compensates for spatial dispersion rather than lateral dispersion).
[0149] Therefore, the second embodiment is summarized as follows. The first medium M1, the second medium M2, the third medium M3, and the fourth medium M4 form a so-called reference amplification unit. The light beam F reflected by the rear portion 22 of the fourth medium M4 and refracted by the front portion 20... R4 The output beam F of the reference amplification unit S The amplification device 10 includes one or more consecutive amplification units identical to the reference amplification unit, each amplification unit being configured to receive the output beam of the preceding amplification unit as an input beam.
[0150] Therefore, the number of amplification units (and thus active laser media) can be adjusted according to the required amplification level.
[0151] Other additions to the second embodiment can also be conceived. For example, a focal-free lens is used to be inserted between the second medium M2 and the third medium M3 along the path of the beam to increase the size of the beam between the second medium M2 and the third medium M3. This optimizes the amplification gain.
[0152] Furthermore, in one variation, a septum is used to be inserted in the beam path between the second medium M2 and the third medium M3. The septum is formed, for example, by two plane mirrors tilted at 45° relative to each other. In this way, different geometric arrangements of the active laser media (“in-line”) can be used.
[0153] According to the third embodiment, such as Figure 4 As can be seen in the reference Figure 1 The same components as those in the amplification device 10 according to the first embodiment will not be repeated. Only the differences will be emphasized.
[0154] In the third embodiment, in addition to the components of the first amplification device 10, the amplification device 10 also includes an optical compensation component 30, which is used to compensate for the beam F at the output of the second active laser medium M2. R2 The broadening amount ΔΦ (the beam reflected by the rear part 22 and refracted by the front part 20) makes the beam F at the output of the amplification device 10... S With the incident beam F I The diameters Φ are basically the same as those of the other two.
[0155] like Figure 4 As shown, the compensation optical assembly 30 includes at least one mirror 40 (plane mirror), which is configured to cause the output beam F of the amplification device 10 to...S Superimposed on the incident beam F I superior.
[0156] Therefore, mirror 40 is configured to direct the beam F at the output of the final medium (in the current case, the second medium M2) R2 The return path is superimposed on the outward path by passing through the active laser medium again.
[0157] Based on the principle of the reversibility of light, this method can compensate for the light beam F at the output of the amplification device 10. S Lateral dispersion in [the medium].
[0158] During operation of the amplification device 10 according to the third embodiment, in addition to the operation described for the first embodiment, the laser beam also travels in the reverse direction, causing the beam exiting through the first medium M1 to be superimposed on the incident beam F. I superior.
[0159] Therefore, in addition to the advantages of the first embodiment, the amplification device 10 according to the third embodiment is used to compensate for the lateral dispersion caused during the passage through the first active laser medium M1 without generating additional losses. On the other hand, since the laser beam passes through the first medium M1 and the second medium M2 again, this compensation is accompanied by additional amplification.
[0160] Those skilled in the art will understand that the embodiments described above can be combined with each other (when such combinations are compatible).
[0161] More specifically, the second and third embodiments are fully compatible, regardless of the number of amplification elements.
[0162] Furthermore, those skilled in the art will understand that the first and third embodiments can be extended to a larger number of continuous active laser media, assuming this number is a multiple of two. For the first embodiment, when this number is a multiple of four, it is equivalent to the second embodiment, and when this number is a multiple of two rather than four, only the advantages of the first embodiment are obtained. For the third embodiment, the advantages of the third embodiment are obtained without considering the number of continuous active laser media, assuming this number is a multiple of two.
[0163] Finally, it should also be understood Figures 1 to 4 This is given as an example of an active laser medium having an angle that places the base of each active laser medium in a plane parallel to the propagation plane of the laser beam (plane (xOz)). However, this angle can take other values, and more specifically, can have non-zero projections in each of planes (xOz) and (yOz).
Claims
1. An amplification device (10) for a multi-wavelength laser beam, the amplification device (10) comprising: A first solid-state active laser medium (M1) having a first refractive index (n1), the first solid-state active laser medium (M1) having a facet with at least two planes, including a facet for receiving a beam referred to as the incident beam (F). I The beam to be amplified has a front portion (20) and a reflective rear portion (22), wherein the front portion (20) is tilted at a first non-zero tilt angle (β1) relative to the rear portion (22), and the rear portion (22) is used for cooling; and A second solid-state active laser medium (M2) having a second refractive index (n2), the second solid-state active laser medium (M2) having a face portion with at least two planes, including a beam (F) for receiving a light beam reflected by the rear face portion (22) of the first solid-state active laser medium (M1) and refracted by the front face portion (20). R1 The first solid-state active laser medium (M1) has a front portion (20) and a reflective rear portion (22), the front portion (20) being tilted at a second non-zero tilt angle (β2) relative to the rear portion (22), the rear portion (22) being used for cooling, and the second solid-state active laser medium (M2) along the beam (F) reflected by the rear portion (22) of the first solid-state active laser medium (M1) and refracted by the front portion (20). R1 The path setting of the second solid-state active laser medium (M2) is such that the orientation of the first non-zero tilt angle (β1), the second non-zero tilt angle (β2), and the second solid-state active laser medium (M2) is such that the output beam (F) forming the second solid-state active laser medium (M2) is... R2 The sub-beams of each wavelength are parallel to each other at the output of the second solid-state active laser medium (M2).
2. The amplification device (10) according to claim 1, wherein, The front portion (20) of the first solid active laser medium (M1) is perpendicular to the axis Oz, and the first non-zero tilt angle (β1) forms an angle on the plane xOz. And form an angle on the plane yOz The second non-zero tilt angle (β2) forms an angle on the plane xOz. And form an angle on the plane yOz It meets the following conditions: and .
3. The amplification device (10) according to claim 1 or 2, wherein the second solid-state active laser medium (M2) is configured relative to the first solid-state active laser medium (M1) such that: The front portion (20) of the second solid-state active laser medium (M2) is parallel to the front portion (20) of the first solid-state active laser medium (M1); and The rear portion (22) of the second solid active laser medium (M2) is parallel to the rear portion (22) of the first solid active laser medium (M1).
4. The amplification device (10) according to claim 1 or 2, wherein, The beam (F) at the output section of the second solid-state active laser medium (M2) R2 ) has the same characteristics as the incident beam (F) I The amplification device (10) includes an optical compensation component (30) to compensate for the diameter (Φ) of the beam at the output of the second solid-state active laser medium (M2) compared to the widened diameter (Φ+ΔΦ). R2 The widening amount (ΔΦ) of the beam (F) at the output of the amplifying device (10) makes the beam (F) at the output of the amplifying device (10) more powerful. S ) has the same characteristics as the incident beam (F) I The diameters (Φ) of the two are substantially equal.
5. The amplification device (10) according to claim 4, wherein, The optical compensation component (30) includes: A third solid-state active laser medium (M3) having a third refractive index (n3), the third solid-state active laser medium (M3) having a facet with at least two planar surfaces, including a portion for receiving the light beam (F) at the output portion of the second solid-state active laser medium (M2). R2 The front part (20) and the reflective rear part (22) are inclined at a third non-zero angle (β3) relative to the rear part (22), and the rear part (22) is used for cooling. A fourth solid-state active laser medium (M4) having a fourth refractive index (n4), the fourth solid-state active laser medium (M4) having at least two planar faces, including a beam (F) for receiving a light beam reflected by the rear face (22) of the third solid-state active laser medium (M3) and refracted by the front face (20). R3 The front portion (20) and the reflective rear portion (22) of the third solid-state active laser medium (M3) are inclined at a fourth non-zero tilt angle (β4) relative to the rear portion (22), the rear portion (22) being used for cooling, the fourth solid-state active laser medium (M4) along the beam (F) reflected by the rear portion (22) of the third solid-state active laser medium (M3) and refracted by the front portion (20). R3 ) path settings, The third non-zero tilt angle (β3), the fourth non-zero tilt angle (β4), the orientation of the third solid-state active laser medium (M3), and the orientation of the fourth solid-state active laser medium (M4) cause the output beam (F) of the fourth solid-state active laser medium (M4) to... S The diameter of the incident beam (F) is approximately equal to that of the incident beam. I The diameter (Φ) of the output beam (F) is determined, and the output beam (F) is formed. S The sub-beams of each wavelength are parallel to each other at the output of the fourth solid-state active laser medium (M4).
6. The amplification device (10) according to claim 5, wherein, The front portion (20) of the third solid-state active laser medium (M3) is perpendicular to the axis Oz, and the third non-zero tilt angle (β3) forms an angle on the plane xOz. And form an angle on the plane yOz The third non-zero tilt angle (β3) forms an angle on the plane xOz. And form an angle on the plane yOz It meets the following conditions: and .
7. The amplification device (10) according to claim 5, wherein, The third solid-state active laser medium (M3) is configured relative to the fourth solid-state active laser medium (M4) such that: The front portion (20) of the third solid-state active laser medium (M3) is parallel to the front portion (20) of the fourth solid-state active laser medium (M4); and The rear face (22) of the third solid active laser medium (M3) is parallel to the rear face (22) of the fourth solid active laser medium (M4).
8. The amplification device (10) according to claim 5, wherein, The first solid-state active laser medium (M1), the second solid-state active laser medium (M2), the third solid-state active laser medium (M3), and the fourth solid-state active laser medium (M4) are the same.
9. The amplification device (10) according to claim 5, wherein, The first solid-state active laser medium (M1), the second solid-state active laser medium (M2), the third solid-state active laser medium (M3), and the fourth solid-state active laser medium (M4) form a so-called reference amplification unit. The light beam (F) reflected by the rear portion (22) of the fourth solid-state active laser medium (M4) and refracted by the front portion (20) is... R4 The output beam (F) of the reference amplification unit is formed. S The amplification device (10) includes one or more consecutive amplification units identical to the reference amplification unit, each of which is configured to receive the output beam of the preceding amplification unit as an input beam.
10. The amplification device (10) according to claim 4, wherein, The optical compensation component (30) includes at least one mirror, which is configured to cause the output beam (F) of the amplification device (10) to... S ) superimposed on the incident beam (F I )superior.