CN101263633A - Club-shaped solid laser device - Google Patents

Abstract

In a symmetrically stable optical resonator, a first reference plane is set at an arbitrary position between the end face (102), opposing a partial reflector (2), and the neutral point (101) of a rod type solid state laser medium (1), and an aperture (5) having a diameter substantially equal to that of the rod type solid state laser medium (1) is arranged at a position optically symmetric to the reference plane with the partial reflector (2) as a neutral point. Using a relay lens (6) and a coupling lens (7) arranged between the aperture (5) and an optical fiber (8), the first reference plane is transfer-relayed onto the incident end face of the optical fiber (8), and the aperture (5) is transferred onto the coupling lens (7) through the relay lens (6).; Even when the focal length of thermal lens of the rod type solid state laser medium (1) or pointing of laser light is varied, beam transmission is performed by an optical fiber excellent in stability and reliability and condensation of laser light exiting the optical fiber is sustained constantly.

Description

Club-shaped solid laser device

Technical field

The present invention relates to a kind of club-shaped solid laser device, it carries out light stimulus and produces laser bar-shaped solid laser medium, makes this laser to optical fiber input simultaneously, carries out the transmission of laser.

Background technology

In existing club-shaped solid laser device, adopt following structure: on the optical axis of laser beam, be provided for the opening of confine optical beam diameter, and make the imaging on the optical fiber input end face of this opening.(for example, with reference to patent documentation 1, patent documentation 2)

Patent documentation 1: the spy opens 2003-78190 communique (0022-0025 section, Fig. 1)

Patent documentation 2: the spy opens 2003-209307 communique (the 0019th section, Fig. 1)

Summary of the invention

Using optical fiber to carry out in the existing club-shaped solid laser device of laser transmission, because the intensity (focal length) of the thermal lens of rod-shaped laser medium changes corresponding to the variation of laser output, so the natural mode of vibration of selecting in the optical resonator that is provided with for output laser changes, the convergent angle of the laser of incident also changes corresponding to laser output power in optical fiber.Under the situation of using refractive index step change type optical fiber, owing to roughly kept, so the angle of divergence of emitting laser is also corresponding with convergent angle and change with laser output power from optical fiber at the convergent angle of inside of optical fibre laser.Here, in optical fiber 8 convergent angle of the laser of incident and from optical fiber 8 angle of divergence of emitting laser, in Figure 15, represent with the angle that is labeled as α.Emitting laser from optical fiber is owing to its beam waist diameter can be considered as and optical fiber core diameter approximately equal, so the variation of the variation of the angle of divergence and optically focused is identical.Therefore, in the existing club-shaped solid laser device, the optically focused of emitting laser changes with laser output power from optical fiber.As mentioned above, in existing club-shaped solid laser device, since along with laser output power from optical fiber the angle of divergence of emitting laser, be the optically focused variation, so for example combine and utilize under the situation of laser with the processing head that constitutes by convergence optical system, produce the problem that the transmitance of the laser by processing head can change with laser output power at outgoing end face with optical fiber.In addition, because the beam diameter to the laser of light-gathering optics incident also changes because of laser output power, so the aberration effects in the convergence optical system is different because of laser output power, the problem that exists the convergent beam diameter also to change because of laser output power.

In addition, in the existing club-shaped solid laser device, owing to do not possess the unit of the influence that prevents the laser alignment change, so under the situation that the laser alignment change takes place, exist laser to change to the convergent angle of optical fiber, the angle of divergence of emitting laser further increases from optical fiber, the problem of optically focused reduction.And; because of the directive property change takes place, the convergent angle of the laser of incident surpasses under the situation of allowing NA of optical fiber in optical fiber, exists laser to leak from optical fiber; make the connector that supports the optical fiber both ends and the protective layer that optical fiber covers is heated, so that cause the problem of damage.

The object of the present invention is to provide a kind of club-shaped solid laser device, it can address the above problem, even under the situation that the thermal lens intensity of club-shaped solid laser medium changes, also the convergent angle of the laser of incident in optical fiber can be kept constant, even under the situation that the beam-pointing of laser changes, also can prevent the damage of optical fiber, can stably supply with laser.

The club-shaped solid laser device that the present invention relates to, it uses relay lens and in conjunction with lens, make laser from the output of symmetrical stable type optical resonator to optical fiber input, this symmetry stable type optical resonator is made of club-shaped solid laser medium and partially reflecting mirror and completely reflecting mirror, wherein, with the club-shaped solid laser medium and the above-mentioned partially reflecting mirror opposing end faces of above-mentioned partially reflecting mirror disposed adjacent, and the optional position between the mid point of this club-shaped solid laser medium, set the 1st datum level, with respect to above-mentioned partially reflecting mirror and with the position of the 1st datum level optics symmetry, set the 2nd datum level, above-mentioned relay lens is configured in following position: make the imaging on the 1st image planes of above-mentioned the 1st datum level, make simultaneously above-mentioned the 2nd datum level above-mentioned in conjunction with lens on imaging, above-mentioned in conjunction with lens configuration in following position: make the imaging on fiber end face of above-mentioned the 1st image planes.

The effect of invention

Because the present invention has aforesaid structure, therefore even under the situation of the focal distance fluctuation of the thermal lens of club-shaped solid laser medium, also can will remain constant in conjunction with beam diameter, light-beam position on lens and the optical fiber input end face, not only can realize the laser transmission of being undertaken by optical fiber that stable and reliability is good, and can be with the optically focused maintenance constant of emitting laser from optical fiber.

Description of drawings

Fig. 1 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 1.

Fig. 2 is the schematic diagram of the club-shaped solid laser medium in the expression embodiments of the present invention 1.

Fig. 3 partially reflecting mirror that to be in club-shaped solid laser medium the configuration of expression in the embodiments of the present invention 1 be made of level crossing and completely reflecting mirror and the structure chart of the symmetrical stable type optical resonator that constitutes.

Fig. 4 be expression use on the optics that two thermal lenss of equal value represent with embodiments of the present invention 1 in the structure chart of symmetrical stable type optical resonator of symmetrical stable type optical resonator equivalence.

Fig. 5 be expression use on the optics that a thermal lens of equal value represents with embodiments of the present invention 1 in the structure chart of symmetrical stable type optical resonator of symmetrical stable type optical resonator equivalence.

Fig. 6 be the laser in the symmetrical stable type optical resonator of expression in the embodiments of the present invention 1 condition shape, be the key diagram of beam propagation state.

Fig. 7 be expression use on the optics that a thermal lens of equal value represents with embodiments of the present invention 1 in the symmetrical stable type optical resonator of symmetrical stable type optical resonator equivalence in laser condition shape, be the key diagram of the spread state of light beam.

Fig. 8 is the curve chart of expression based on the propagation state of light beam in the optical system of embodiments of the present invention 1 design.

Fig. 9 is that to optical fiber in the convergent angle of the light beam of incident of expression in the embodiments of the present invention 1 is with respect to the curve chart of laser output power.

Figure 10 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 2.

Figure 11 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 3.

Figure 12 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 4.

Figure 13 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 5.

Figure 14 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 6.

Figure 15 is the figure of explanation convergent angle of the laser of incident in optical fiber.

Embodiment

Execution mode 1

Fig. 1 is the schematic diagram of the formation of the club-shaped solid laser device in the expression embodiments of the present invention 1.Among Fig. 1,1 expression club-shaped solid laser medium, the mid point of 101 expression club-shaped solid laser media 1, the end face of 102 expression club-shaped solid laser media 1.Solid laser medium 1 in the present embodiment, use has been mixed as YAG (yttrium-aluminium-garnet) crystallization of the Nd (neodymium) of active medium.The 2nd, partially reflecting mirror, the 3rd, completely reflecting mirror, the 4th, laser.Constitute optical resonator by partially reflecting mirror 2 and completely reflecting mirror 3, utilize to use lamp source and semiconductor laser and by the club-shaped solid laser medium of light stimulus output laser.5 are arranged on the aperture on the light path of laser 4, and it has the opening diameter of the diameter that is substantially equal to club-shaped solid laser medium 1.The 6th, focal length is the relay lens of f1, the 7th, focal length be f2 in conjunction with lens.The 8th, optical fiber, the incident end face of 81 expression optical fiber.Passed through the laser 4 of aperture 5, by relay lens 6 to transmitting in conjunction with lens 7.Utilize in conjunction with lens 7 convergences, by incident end face 81 incident in optical fiber 8 of optical fiber to the laser 4 that transmits in conjunction with lens 7.What dot 9 is thermal lenss of equal value, be with excitation after clava laser medium 1 in, begin to be positioned at the thermal lens composition thin lens optically of equal value in the zone of partially reflecting mirror 2 sides, the 1st image planes of 10 expressions the 1st imaging optical system described later from mid point 101.

In the present embodiment, use the partially reflecting mirror 2 and the completely reflecting mirror 3 that are made of level crossing, the end face at distance club-shaped solid laser medium 1 is position configuration partially reflecting mirror 2 and the completely reflecting mirror 3 of Lm respectively, thereby constitutes symmetrical stable type resonator.Therefore, can guarantee at club-shaped solid laser medium 1 that the light beam mode in the optical resonator has symmetry with respect to the mid point 101 of club-shaped solid laser medium 1 by ideally evenly under the situation of excitation.

In addition, in the present embodiment, at distance partially reflecting mirror 2 is on the position of L1, the configuration opening diameter roughly with the aperture 5 of the equal diameters of club-shaped solid laser medium 1, be on the position of L2 at distance aperture 5, disposing focal length is the relay lens 6 of f1, at distance relay lens 6 is on the position of L3+L4, the configuration focal length be f2 in conjunction with lens 7, be on the position of L5 in distance in conjunction with lens 7, dispose the incident end face 81 of optical fiber 8.In addition, the principal plane locations of thermal lens 9 of equal value, the end face 102 that is positioned at apart from club-shaped solid laser medium 1 is the position of Lt1.

In the present embodiment, relay lens 6 and constitute the 1st imaging optical system in conjunction with lens 7, it becomes the relaying imaging arrangement, promptly, at first with the interarea of thermal lens 9 of equal value by relay lens 6 imaging on the 1st image planes 10, then with the 1st image planes 10 by in conjunction with lens 7 imaging on as the incident end face 81 of the optical fiber 8 of the 2nd image planes.Therefore, be n if make the refractive index of club-shaped solid laser medium 1, then the distance L t1 of the interarea by will be from plane rod end 102 to thermal lens 9 of equal value is scaled optical distance, and the 1st imaging optical system satisfies the relation that is provided by (1) formula and (2) formula.

$\frac{1}{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">f</figure-callout>}1}=\frac{1}{\frac{\mathrm{Ltl}}{n}+\mathrm{Lm}+\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">L</figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">L</figure-callout>}2}+\frac{1}{L3}---\left(1\right)$

$\frac{1}{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">f</figure-callout>}2}=\frac{1}{\mathrm{<figure-callout\; id="4"\; label="L"\; filenames="A20058005156100311.png,A20058005156100343.png"\; state="\{\{state\}\}">L</figure-callout>}4}+\frac{1}{L5}---\left(2\right)$

In addition, in the present embodiment, relay lens 6 constitutes the 2nd imaging optical system, with aperture 5 by relay lens 6 imaging in conjunction with lens 7.Therefore, the 2nd imaging optical system satisfies the relation that (3) formula provides.

$\frac{1}{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">f</figure-callout>}2}=\frac{1}{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">L</figure-callout>}2}+\frac{1}{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="A20058005156100314.png,A20058005156100351.png"\; state="\{\{state\}\}">L</figure-callout>}3+L4}---\left(3\right)$

Below, utilize the schematic diagram of club-shaped solid laser medium 1 shown in Figure 2, the thermal lens of the club-shaped solid laser medium 1 that plays an important role in the present embodiment is elaborated.Among Fig. 2, in 91 presentation graphs shown in the dotted line in the club-shaped solid laser medium 1, the thin lens optically of equal value, the thermal lens composition thin lens optically of equal value in left side among the figure of 92 expressions and mid point 101 in addition with the thermal lens composition on right side among the figure of mid point 101.In addition, the shadow region of representing by length L pump, expression is by the excitation area of discharge lamp and semiconductor laser irradiation exciting light, and the two end portions of the club-shaped solid laser medium of being represented by length L end 1 is represented non-excitation area.Herein for simplicity, the excitation densities of supposing excitation area inside is uniform perfect condition.

The thermal lens of club-shaped solid laser medium 1 is heating itself because rod-shaped laser medium 1 is followed excitation, because of formation temperature in the section of rod-shaped laser medium 1 distribution produces.Under the situation that rod-shaped laser medium 1 is energized, in excellent section, form central temperature height and the low chevron Temperature Distribution of outer edge temperature.Because the refractive index of club-shaped solid laser medium 1 roughly is directly proportional with temperature, so, present converging action with the refraction index profile of Temperature Distribution generation.This converging action is called as the thermal lens phenomenon.In the present embodiment, at first consider mid point 101, be arranged in the thermal lens of the right side area of Fig. 2 with respect to club-shaped solid laser medium 1.

The thermal lens thickness of the right side area of mid point 101 is Lpump/2.The thermal lens that will have this thickness is replaced into the identical and optically of equal value thin lens of focal length, becomes the thermal lens of equal value 91 that dotted line is represented.Under the uniform situation of excitation area underexcitation density, the interarea of thermal lens 91 of equal value is positioned at the mid point of the actual thermal lens with thickness.Thereby the distance of representing with Ltp from the excitation area end to thermal lens interarea of equal value is provided by (4) formula.

$\mathrm{Ltp}=\frac{\mathrm{Lpump}}{4}---\left(4\right)$

Thereby the distance L t1 from the endface position B of club-shaped solid laser medium 1 to thermal lens 91 interareas of equal value uses long Lrod of rod and excitation area length L pump to be represented by (5) formula.

$\mathrm{Ltl}=\frac{\mathrm{Lrod}}{2}-\frac{\mathrm{Lpump}}{4}---\left(5\right)$

In addition, among Fig. 2,92 expressions are positioned at the thermal lens of equal value in left side with respect to the mid point 101 of club-shaped solid laser medium 1.

Fig. 3 represents the structure of symmetrical stable type optical resonator, it is for the club-shaped solid laser medium 1 shown in Fig. 2, the partially reflecting mirror 2 and the completely reflecting mirror 3 that will be made of level crossing, two end faces that are configured in respectively apart from club-shaped solid laser medium 1 are on the position of Lm.Fig. 4 is for symmetrical stable type optical resonator shown in Figure 3, uses symmetrical stable type optical resonator of equal value on the optics of thermal lens of equal value 91,92 expressions.As shown in Figure 4, in the symmetrical stable type optical resonator that uses thermal lens 91,92 expressions of equal value, the two is positioned at the mid point of symmetrical stable type optical resonator thermal lens of equal value 91,92.As shown in Figure 5, be configured in the thermal lens of equal value with the same focal length 91,92 of same position, can replace with focal length and be 1/2nd single thin lens 93 of thermal lens 91,92 of equal value.Optical distance from the interarea of thin lens shown in Figure 5 93 to partially reflecting mirror 2 and completely reflecting mirror 3, equate with optical distance from the interarea of thermal lens of equal value 91 shown in Figure 3 to partially reflecting mirror 2 and optical distance from the interarea of thermal lens 92 of equal value to completely reflecting mirror 3, if consider that the refractive index of club-shaped solid laser medium 1 is n, then can obtain the free space of Lt1/n+Lm.

Fig. 6 represents the condition shape of the laser in the symmetrical stable type optical resonator shown in Figure 3, i.e. beam propagation state.Among Fig. 6, the 41st, the light beam outer contoured shape of the laser in the symmetrical stable type optical resonator.Fig. 7 represents the thermal lens with club-shaped solid laser medium 1 shown in Figure 5, with the condition shape of the laser in the symmetrical stable type optical resonator that obtains after the displacement of the thin lens of the first-class valency of optics, be the beam propagation state.Among Fig. 7, the light beam outer contoured shape of the laser in the symmetrical stable type optical resonator of 42 expressions, 43 expressions are from the light beam outer contoured shape of partially reflecting mirror 2 emitting lasers.In the perfect symmetry stable type optical resonator that the club-shaped solid laser medium is encouraged equably, with respect to the mid point of resonator, the symmetry of mode is guaranteed.In addition in Fig. 6 and the symmetrical stable type optical resonator shown in Figure 7, because partially reflecting mirror 2 and completely reflecting mirror use level crossing, so according to the boundary condition of optical resonator, the corrugated of the laser on partially reflecting mirror 2 and the completely reflecting mirror 3 must become the plane.In other words, must form beam waist on partially reflecting mirror 2 and the completely reflecting mirror 3.Its result, shown in Fig. 6 and Fig. 7 in the symmetrical stable type optical resonator, the beam diameter maximum of mid point.As shown in Figure 6, in the symmetrical stable type optical resonator of reality, the mid point O of resonator is positioned at mid point 101 in the inside of club-shaped solid laser medium.Thereby, the opening diameter that in the symmetrical stable type optical resonator beam diameter is limited, the equal diameters of the club-shaped solid laser medium 1 of making peace greatly.In excitable media, because horizontal multimode excitation, so the beam diameter maximum of laser expands opening diameter to.Thereby even in the thermal lens intensity of club-shaped solid laser medium 1, be under the situation of focal length variations of thermal lens, the beam diameter of the laser at mid point 101 places of club-shaped solid laser medium 1 also can keep being substantially equal to the diameter of club-shaped solid laser medium 1.That is to say that even the focal length variations of thermal lens, the beam diameter d at the interarea place of thin lens 93 in Fig. 7 also can keep being substantially equal to the diameter of club-shaped solid laser medium 1.

In addition, as mentioned above, in the present embodiment, because partially reflecting mirror 2 uses level crossing, so will inevitably form beam waist on the partially reflecting mirror 2.In free space, because the symmetry at the front and back of beam waist beam diameter is guaranteed, so as shown in Figure 7, outgoing from partially reflecting mirror 2, the beam diameter d ' that position O ' behind the propagation distance Lt1/n+Lm locates also equates with the beam diameter d of resonator midpoint.Like this, after partially reflecting mirror 2 outgoing, the beam diameter that the position O ' of distance L t1/n+Lm locates, also with the thermal lens state of club-shaped solid laser medium 1 irrespectively, always keep roughly equal diameters with club-shaped solid laser medium 1.

Here, the object plane with the 1st imaging optical system is called the 1st datum level.The beam diameter of the laser at the 1st datum level place, wish with the thermal lens of club-shaped solid laser medium irrespectively, constant.Therefore, in the present embodiment, the interarea of the thermal lens of equal value 91 in the club-shaped solid laser medium 1 is set at the 1st datum level.In addition, be that the position of central optical symmetry is called the 2nd datum level with the 1st datum level with partially reflecting mirror 2.In the present embodiment, when the 2nd datum level is positioned at the position of O ' of Fig. 7, becomes the beam diameter of laser and the beam diameter on the 1st datum level and keep about equally position.In the present embodiment, configuration aperture 5 on the 2nd datum level.

In the present embodiment shown in Figure 1, the distance L 1 between partially reflecting mirror 2 and the aperture 5 is configured to equate with Lt1/n+Lm as mentioned above.Promptly

$\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">L</figure-callout>}1=\frac{\mathrm{Ltl}}{n}+\mathrm{Lm}=\frac{\mathrm{Lrod}/2+\mathrm{Lpump}/4}{n}+\mathrm{Lm}---\left(6\right)$

Therefore, the beam diameter of the laser on the aperture 5, light-beam position, irrelevant with the thermal lens state of club-shaped solid laser medium 1, maintenance always is substantially equal to the diameter of club-shaped solid laser medium 1.

Execution mode constitutes, and uses the 1st imaging optical system, with the interarea of the thermal lens of equal value 91 in the club-shaped solid laser medium 1, is imaged on the incident end face 81 of optical fiber 8.Because on the interarea of the thermal lens of equal value 91 of the object plane that is equivalent to the 1st imaging optical system, beam diameter and thermal lens state irrelevant and keep with the diameter of club-shaped solid laser medium 1 about equally, and, assurance is present in the inside of club-shaped solid laser medium 1, so on incident end face 81 as the optical fiber 8 of the image planes of the 1st imaging optical system, for beam diameter and light-beam position, also irrelevant with the thermal lens state of club-shaped solid laser medium, can always keep constant.

The imaging multiplying power M1 of the 1st imaging optical system in the present embodiment and the relation of the distance between each optical element are provided by (7) formula.

$\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">M</figure-callout>}1=\frac{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="A20058005156100314.png,A20058005156100351.png"\; state="\{\{state\}\}">L</figure-callout>}3}{\frac{\mathrm{Ltl}}{n}+\mathrm{Lm}+\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">L</figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">L</figure-callout>}2}\&times;\frac{L5}{L4}---\left(7\right)$

Usually, the value of the imaging multiplying power M1 of the 1st imaging optical system can suitably be determined according to the core diameter of the diameter of employed club-shaped solid laser medium 1 and optical fiber 8.For example, under the situation of the optical fiber 8 of the club-shaped solid laser medium 1 that uses diameter 5mm, core diameter 0.4mm, if with respect to the core diameter of optical fiber 8, be that benchmark makes laser incident with 90%, then the imaging multiplying power of the 1st imaging optical system is 0.072.

In addition, in the present embodiment, with partially reflecting mirror 2 be mid point and with the position of the interarea optics symmetry of the thermal lens of equal value 91 of club-shaped solid laser medium 1, the diameter aperture 5 about equally of configuration opening diameter and club-shaped solid laser medium 1.And, use the 2nd imaging optical system, with aperture 5 imaging in conjunction with lens 7.Therefore, with the thermal lens state of club-shaped solid laser medium 1 irrespectively, the beam diameter at aperture 5 places roughly keeps the equal diameters with club-shaped solid laser medium 1.Whether therefore, if from partially reflecting mirror 2 emitting lasers 4 the directive property change does not take place, exist no matter then see through the beam diameter aperture 5 of the laser of aperture 5, all basic maintenance is constant.Therefore, as the image planes of the 2nd imaging optical system in conjunction with beam diameter on the lens 7 and light-beam position, irrelevant and can guarantee with the thermal lens state of club-shaped solid laser medium.In addition, taking place under the situation of directive property change from partially reflecting mirror 2 emitting lasers 4, can not see through aperture 5 owing to be positioned at the laser 4 of aperture 5 open outer side,, always be present in the opening scope of aperture 5 so it is irrelevant to see through the laser and the directive property change of aperture 5.Therefore, as the image planes of the 2nd imaging optical system in conjunction with the laser radiation scope on the lens 7, always be included in the range of exposures under the situation that does not have the directive property change.Therefore, the convergent angle of the laser of incident also keeps the value of constant in optical fiber 8.

In addition as mentioned above, show on object plane and dispose aperture, stipulate the structure of light-beam position physically as the 2nd imaging optical system of the 2nd datum level.Yet, as mentioned above, under the situation that does not have the directive property change, no matter having or not of aperture, all have nothing to do and constant in conjunction with the beam diameter on the lens 7 with thermal lens, if so for example the change at little and beam convergence incident in optical fiber the angle of directive property change then also can be adopted the not structure of configuration aperture on the object plane of the 2nd imaging optical system within permissible range.Also be similarly in the following execution mode.

In addition, the relation of the imaging multiplying power M2 of the 2nd imaging optical system in the present embodiment and the distance between each optical element is provided by (8) formula.

$\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">M</figure-callout>}2=\frac{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="A20058005156100314.png,A20058005156100351.png"\; state="\{\{state\}\}">L</figure-callout>}3+L4}{L2}---\left(8\right)$

In addition, the value of the imaging multiplying power M2 of common the 2nd imaging optical system, can according to desired to optical fiber 8 incidents the beam convergence angle and suitably determine.For example, from being 50mm in conjunction with lens 7 to the distance L 5 of the incident end face 81 of optical fiber, the convergent angle when optical fiber 8 incidents is under the situation of 0.20rad, if the incident beam diameter is 10mm in conjunction with lens 8, then can make convergent angle be about 0.20rad in hope.Here, be 5mm if make the diameter d of club-shaped solid laser medium, then the opening diameter of the beam diameter d ' at the 2nd datum level place or aperture 5 is 5mm, therefore the value of the imaging multiplying power M2 of the 2nd imaging optical system is set at 2.0 and gets final product.This relation, if as shown in Figure 15, the half-angle that makes convergent angle is θ, then as (9) formula.

$\mathrm{<figure-callout\; id="2"\; label="M"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">M</figure-callout>}2=\frac{2\&times;\mathrm{<figure-callout\; id="5"\; label="L"\; filenames="A20058005156100311.png,A20058005156100331.png"\; state="\{\{state\}\}">L</figure-callout>}5\&times;\tan \mathrm{\&theta;}}{d}---\left(9\right)$

Here, the relational expression of the configuration of decision lens etc. is (1) (2) (3) (7) (8) (9) and these 7 formula of (10) formula of providing the optical system total length L.

L＝L1+L2+L3+L4+L5 (10)

By using various preconditions to find the solution above-mentioned formula, can calculate relay lens and in conjunction with the correct position of lens.For example, if the structure of known resonator, then Lt1, n, Lm, L1 are known constants.In addition, if the size of laser pumping device determines that also then L also is known constant.In addition, the diameter of club-shaped solid laser medium and the diameter of optical fiber are normally known, and therefore the imaging multiplying power M1 of the 1st imaging optical system also is known constant.Therefore, under this situation, variable is these 7 of L2, L3, L4, L5, f1, f2, M2, can determine variable by above-mentioned 7 formulas.In addition, if for example for shared lens and the relay lens of combining of other laser aids, wish under the fixing situation of focal distance f 1, f2, because the length of optical system has the degree of freedom, so by deletion (10) formula, perhaps make the structure of resonator have the degree of freedom, Lt1 and Lm as variable, are determined the configuration of each lens.

Fig. 8 is based on present embodiment and in the optical system that designs, the curve chart of expression beam propagation situation, and the longitudinal axis is represented beam diameter, transverse axis is represented from the distance of end face 102 beginnings of club-shaped solid laser medium 1.Among Fig. 8, the curve of the beam diameter during the low power output of 201 expressions, during the long state of the focal length of thermal lens, the curve of the beam diameter in 202 expressions during power output, when the focal length of thermal lens is moderate, the curve of the beam diameter during 203 expression high-output powers, during the short state of thermal focal length.Beam propagation situation in optical system when design example shown in Figure 8, expression are used the club-shaped solid laser medium 1 of diameter 4mm, the beam diameter at aperture 5 places and thermal lens have nothing to do as can be known, with the diameter 4mm of club-shaped solid laser medium 1 about equally.In addition, in the 1st image planes 10 of the 1st imaging optical system and in conjunction with lens 7, beam diameter is also irrelevant with the state of thermal lens, keeps constant.Because incident beam diameter and thermal lens in conjunction with lens 7 places are irrelevant, are always constant value, so the convergent angle of the laser of incident also roughly keeps constant value in optical fiber 8.

Fig. 9 is the curve chart of the beam convergence angle of expression when optical fiber input with respect to laser output power.Among Fig. 9,301 expressions are based on the beam convergence angle of the optical system of present embodiment design, the 302nd, the convergent angle of existing optical system.In existing design of Optical System, be accompanied by the increase of laser output power, the convergent angle when optical fiber input can reduce, relative with it, in the optical system based on present embodiment, convergent angle when optical fiber input and laser output power irrespectively keep constant substantially.Because under the situation of the optical fiber that uses refractive index step (SI) type, the angle of divergence of light beam is kept ideally in optical fiber, if so based on present embodiment design optical system, then for the light beam of outgoing from optical fiber 8, also can with laser output power irrespectively, keep the optically focused of constant.

The following method of knowing clearly shown in the present embodiment: clearly stipulate excitation area, at the uniform ideal situation of excitation area underexcitation density, suppose the thermal lens of club-shaped solid laser medium 1, set the configuration of optical system for supposition.Yet, in fact using discharge lamp and semiconductor laser, under the situation that club-shaped solid laser medium 1 is encouraged, because excitation reflection of light in the club-shaped solid laser medium 1 and scattering etc., the border of excitation area and non-excitation area is also indeterminate.The method of the calculating thermal lens interarea shown in the present embodiment is not necessarily very accurate, but as long as the interarea of setting thermal lens of equal value is the 1st datum level near the position that provides in (5) formula.For example, from the end face 102 of club-shaped solid laser medium 1 in the scope the mid point 101, set thermal lens interarea of equal value arbitrarily as the 1st datum level, also can access same effect.Key is, as long as with partially reflecting mirror 2 be mid point and with the position of the interarea optics symmetry of the thermal lens of setting of equal value on, set the 2nd datum level, utilization is by relay lens 5 and the 1st imaging optical system that constitutes in conjunction with lens 7, interarea imaging on the incident end face 82 of optical fiber 8 with thermal lens 9 of equal value, simultaneously, use the 2nd imaging optical system that constitutes by relay lens 6, the imaging in conjunction with lens of the 2nd datum level is got final product.If necessary, opening diameter can be substantially equal to the aperture 5 of the diameter of club-shaped solid laser medium 1, be configured on the 2nd datum level.

In addition, in the present embodiment, show and use relay lens and in conjunction with lens, constitute the embodiment of the 1st imaging optical system and the 2nd imaging optical system, but constitute the lens of the 1st imaging optical system and the 2nd imaging optical system, be not defined as and use relay lens and in conjunction with these 2 on lens.For example, also the lens of equal value that constitute by 2 lens can be considered as relay lens, constitute the 1st and the 2nd imaging optical system, not only can obtain the effect same with present embodiment, if and owing to the variable in distance that makes between 2 lens that constitute relay lens, then compare equivalence optically, therefore when the imaging multiplying power that keeps the 1st, the 2nd imaging optical system is constant, can easily change optical path length with the situation of the focal length variations that makes relay lens.

In addition, in the present embodiment, show and use single lens, but use compound lens as obtaining same effect in conjunction with lens as structure in conjunction with lens, and can reduce the influence of spherical aberration, increase the adjustment surplus of incident beam in optical fiber.

In the following embodiments, describe, but as mentioned above relay lens or all can constitute respectively by a plurality of lens in conjunction with lens by the device that single lens constitutes with relay lens with in conjunction with lens.

Execution mode 2

Figure 10 (a) is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 2.In Figure 10 (a), the 11st, inner aperture is configured in apart from partially reflecting mirror 2 and is the optical resonator inside of La.In the present embodiment, the beam diameter of the laser in the optical resonator is by the so-called transverse mode of inner aperture 11 restrictions.Therefore, the beam diameter and the light-beam position of the laser at inner aperture 10 places, irrelevant and keep constant with the thermal lens state of club-shaped solid laser medium 1.That is, the 1st datum level in the present embodiment becomes the position of inner aperture 11.

In the present embodiment, with partially reflecting mirror 2 be the center and with i.e. the 2nd datum level place, the position of inner aperture 11 optics symmetries, configuration opening diameter and inner aperture 11 aperture 5 about equally.That is, (11) formula is set up.

L1＝La (11)

At partially reflecting mirror 2 places, according to the boundary condition of optical resonator, guarantee to be beam waist, therefore owing to the symmetry of beam propagation, at aperture 5 places, beam diameter and light-beam position are also irrelevant with the thermal lens state of club-shaped solid laser medium 1, keep constant.

In addition, in the present embodiment, also with above-mentioned execution mode 1 similarly, constitute the 1st imaging optical system by relay lens 6 with in conjunction with lens 7.But, in the present embodiment, with inner aperture 11 as object plane, at first with inner aperture 11 by relay lens 6 imaging on the 1st image planes 10.For the 1st image planes 10, with above-mentioned execution mode 1 in the same manner, by on the incident end face 81 of optical fiber 8, becoming to dwindle the relaying picture in conjunction with lens 7.In addition, in the present embodiment, owing to make inner aperture 11 become the object plane of the 1st imaging optical system, so (1) formula of the image-forming condition on expression the 1st image planes shown in the above-mentioned execution mode 1 is deformed into (1 ') formula

$\frac{1}{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">f</figure-callout>}1}=\frac{1}{\mathrm{La}+\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">L</figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">L</figure-callout>}2}+\frac{1}{L3}---\left(1^{\&prime;}\right)$

In addition, about (2) formula, also can directly be suitable in the present embodiment.In addition, in the present embodiment, also with above-mentioned execution mode 1 similarly, constitute the 2nd imaging optical system by relay lens 6, aperture 5 is by relay lens 6 imaging in conjunction with lens 7.Thereby the relation shown in the above-mentioned execution mode 1 in (3) formula can directly be suitable for present embodiment.

In the present embodiment, the imaging multiplying power M1 of the 1st imaging optical system is provided by (7 ') formula.

$\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">M</figure-callout>}1=\frac{\mathrm{<figure-callout\; id="3"\; label="L"\; filenames="A20058005156100314.png,A20058005156100351.png"\; state="\{\{state\}\}">L</figure-callout>}3}{\mathrm{La}+\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">L</figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">L</figure-callout>}2}\&times;\frac{L5}{L4}---\left(7^{\&prime;}\right)$

In addition, the imaging multiplying power M2 of the 2nd imaging optical system, with above-mentioned execution mode 1 in the same manner, can calculate according to (8) formula.About the imaging multiplying power M1 of the 1st imaging optical system, the imaging multiplying power M2 of the 2nd imaging optical system, as long as opening diameter according to inner aperture 11, at the beam diameter on the incident end face 81 of desired optical fiber 8, beam convergence angle when optical fiber 8 incidents, set suitable value and get final product.

In the present embodiment, beam diameter on the object plane of the 1st imaging optical system and light-beam position, owing to aperture 11 is guaranteed, therefore, for the image planes of the 1st imaging optical system the beam diameter and the light-beam position of the laser 4 on the incident end face 81 of optical fiber 8, also with the thermal lens state of club-shaped solid laser medium 1 irrespectively, can always keep constant.

In addition, present embodiment constitutes, with partially reflecting mirror 2 be mid point and with as i.e. the 2nd datum level place, the position of the inside aperture 11 optics symmetries of the 1st datum level, configuration opening diameter and inner aperture 11 aperture 5 about equally use the 2nd imaging optical system to make aperture 5 in conjunction with lens 7 places imaging.Therefore, the thermal lens state of beam diameter on the aperture 5 and club-shaped solid laser medium 1 irrespectively, the opening diameter of maintenance and inner aperture 11 about equally, on this basis, can not see through aperture 5 owing to be positioned at the laser 4 of the open outer side of aperture 5, even so under the situation of partially reflecting mirror 2 emitting laser generation directive property variations etc., the image planes of the 2nd imaging optical system promptly also can be guaranteed in conjunction with beam diameter on the lens 7 and light-beam position.Its result, the convergent angle of the laser 4 of incident in optical fiber 8, with the thermal lens state of club-shaped solid laser medium 1 irrespectively, basic maintenance is constant, for emitting laser 4 from optical fiber 8, also with laser output power irrespectively, can keep the optically focused of constant.

As mentioned above, inner aperture 11 is configured between club-shaped solid laser medium 1 and the partially reflecting mirror 2, but also can be configured between club-shaped solid laser medium 1 and the completely reflecting mirror 3.Under this situation, because the symmetry of the laser beam in the resonator, and depart from the situation equivalence that with the situation of the above-mentioned distance configuration identical, promptly is configured in the position of symmetry from partially reflecting mirror 2 with respect to the center 101 of club-shaped solid laser medium 1 apart from completely reflecting mirror 3 in partially reflecting mirror 2 sides.For example, shown in Figure 10 (b), under the situation of completely reflecting mirror 3 lateral extent completely reflecting mirrors 3 for the inner aperture 11 of La place configuration, the effect of inner aperture 11 and Figure 10 (a) equivalence.Therefore, the configuration of optical system by shown in Figure 10 (b), is disposed comparably with Figure 10 (a), can obtain identical result.

In addition, shown in present embodiment, about partially reflecting mirror 2 is used level crossing, the structure that the beam diameter of optical resonator inside is limited by inner aperture 11, be not limited to the symmetric form resonator structure, for asymmetric resonator, if, then can access the effect identical with present embodiment according to present embodiment configuration aperture 5, relay lens 6, in conjunction with lens 7 and optical fiber 8.

Execution mode 3

Figure 11 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiment of the present invention 3.In the present embodiment, use, make end face 102 imaging on the 1st image planes 10 of club-shaped solid laser medium 1, simultaneously, make the imaging on the incident end face 81 of optical fiber 8 of the 1st image planes 10 by relay lens 6 and in conjunction with the 1st imaging optical system that lens 7 constitute.In addition, with above-mentioned execution mode 1,2 in the same manner, constitute the 2nd imaging optical system by relay lens 6, form the structure make aperture 5 imaging in conjunction with lens 7.

In the present embodiment, with partially reflecting mirror 2 be the center and with the position of the end face 102 optics symmetries of club-shaped solid laser medium 1, the configuration opening diameter is substantially equal to the aperture 5 of the diameter of club-shaped solid laser medium 1.That is, (11 ') formula is set up.

L1＝Lm (11′)

Thereby the image-forming condition on the 1st image planes is according to (1 ") formula provides.

$\frac{1}{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">f</figure-callout>}1}=\frac{1}{\mathrm{Lm}+\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="A20058005156100331.png"\; state="\{\{state\}\}">L</figure-callout>}1+\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20058005156100311.png,A20058005156100312.png"\; state="\{\{state\}\}">L</figure-callout>}2}+\frac{1}{L3}---\left(1^{\&prime;\&prime;}\right)$

In addition, provide (2) formula of the image-forming condition on the incident end face 81 of optical fiber 8 and provide (3) formula, also can directly be suitable for for present embodiment in conjunction with the image-forming condition on the lens 7.

In the present embodiment, the object plane that the end face 102 of club-shaped solid laser medium 1 is set at the 1st imaging optical system i.e. the 1st datum level.The variation of the end face beam diameter 102 places, when thermal lens changes of club-shaped solid laser medium 1, compare bigger with the interarea of the thermal lens of equal value 9 of above-mentioned execution mode 1 and inside aperture 11 places of above-mentioned execution mode 2, but except the situation of utilizing confine optical beam diameters such as inner aperture 11, compare less with the variation of the beam diameter of club-shaped solid laser medium 1 outside, and light beam can guarantee always to be positioned at the end face 102 of club-shaped solid laser medium 1.Therefore, the light beam of imaging on by the incident end face 81 of the 1st imaging optical system at optical fiber 8, with as the light beam maximum gauge of plane rod end 102 places of object plane supposition, be under the situation of equal diameters of club-shaped solid laser medium 1, compare with the light beam of imaging on optical fiber input end face 81, guarantee always to be positioned at the inboard.Its result is even under the situation that the thermal lens of club-shaped solid laser medium 1 changes, at the incident end face 81 of optical fiber 8, also can always remain on laser 4 the in-core portion of optical fiber 8.

In addition, since aperture 5 be configured in partially reflecting mirror 2 be mid point and with the 2nd datum level as the end face 102 optics symmetries of the club-shaped solid laser medium 1 of the 1st datum level on, therefore, because the symmetry of beam propagation, for the beam diameter on the aperture 5, always can guarantee diameter less than club-shaped solid laser medium 1.On this basis, the opening diameter of aperture 5 be set at the diameter of club-shaped solid laser medium 1 about equally, therefore, even under the situation of the directive property change of laser 4, also always keep constant in conjunction with the light-beam position on the lens 7, and beam diameter is always less than the constant value by the imaging multiplying power decision of the opening diameter of aperture 5 and the 2nd imaging optical system.Like this, no matter the state of the thermal lens of club-shaped solid laser medium 1 how, always the convergent angle of the laser of incident keeps being less than or equal to steady state value in optical fiber 8, for emitting laser 4 from optical fiber 8, also with laser output power irrespectively, can keep optically focused more than or equal to steady state value.

Execution mode 4

The schematic diagram of the structure of the club-shaped solid laser device in Figure 12 (a) expression embodiments of the present invention 4.Among Figure 12 (a), 1a is illustrated in partially reflecting mirror 2 that utilization is made up of level crossing, completely reflecting mirror 3 and the 1st club-shaped solid laser medium that disposes in the optical resonator that constitutes, 1b represents the 2nd club-shaped solid laser medium, and the length of the 1st and the 2nd club-shaped solid laser medium 1a, 1b is Lrod.In addition, in the present embodiment, with the distance setting between partially reflecting mirror 2 and the 1st club-shaped solid laser medium 1a is Lm, with the distance setting between the 1st club-shaped solid laser medium 1a and the 2nd club-shaped solid laser medium 1b is 2Lm, with the distance setting between the 2nd club-shaped solid laser medium 1b and the completely reflecting mirror 3 is Lm, constitutes so-called preiodic type resonator.Therefore, under the ideal conditions that the 1st and the 2nd solid laser medium 1a, 1b are encouraged equably, beam diameter among the 1st and the 2nd club-shaped solid laser medium 1a, the 1b, condition shape in other words are with the single club-shaped solid laser medium 1 of use for example shown in Figure 6 and to constitute the situation of symmetrical stable type optical resonator identical.That is,, then use a plurality of club-shaped solid laser media 1 if constitute periodically resonator, can optically focused is remained constant in, easily realize high-output powerization.

In the present embodiment, for aperture 5, relay lens 6, in conjunction with the incident end face 81 of lens 7, optical fiber 8, with the baseline configuration identical with above-mentioned execution mode 1.Promptly, the end face 102 that will be positioned at distance the 1st club-shaped solid laser medium 1a for the interarea of the thermal lens of equal value 9 at Lt1 place as the 1st datum level, with partially reflecting mirror 2 be mid point and with the i.e. configuration aperture 5 on the 2nd datum level in the position of the 1st datum level optics symmetry, the diameter of the opening diameter of this aperture 5 and club-shaped solid laser medium 1a is about equally.Constitute the 1st imaging optical system by relay lens 6 with in conjunction with lens 7, the interarea that makes thermal lens 9 of equal value is by relay lens 6 imaging on the 1st image planes, simultaneously, makes the 1st image planes 10 by in conjunction with lens 7 imaging on the incident end face 81 of optical fiber 8.In addition, constitute the 2nd imaging optical system, make aperture 5 imaging in conjunction with lens 7 by relay lens 6.

As described in present embodiment, in single optical resonator, dispose under the situation of a plurality of club-shaped solid laser media 1 and formation preiodic type resonator, if utilize the method identical with above-mentioned execution mode 1, configuration aperture 5, relay lens 6, in conjunction with the incident end face 81 of lens 7, optical fiber 8, then not only can obtain the effect same with above-mentioned execution mode 1, and can in the optically focused that keeps constant, easily realize high-output powerization.

In addition, in the present embodiment, show the structure of configuration 2 club-shaped solid laser medium 1a, 1b in single optical resonator, but the number of the club-shaped solid laser medium 1 that disposes is not limited thereto in optical resonator.For example, as long as according to desired laser output power, selection is configured in the number of the club-shaped solid laser medium 1 in the optical resonator, with the distance between the distance between partially reflecting mirror 2 and the club-shaped solid laser medium 1 that is adjacent and completely reflecting mirror 2 and the club-shaped solid laser medium 1 that is adjacent, be set at Lm, be 2Lm with the distance setting between the relative club-shaped solid laser medium 1 simultaneously, no matter then the number of club-shaped solid laser medium 1 how, can both constitute the preiodic type resonator.

In addition, in the present embodiment that a plurality of club-shaped solid laser media 1 is configured in the single optical resonator, with above-mentioned execution mode in the same manner, the interarea of the thermal lens of equal value 9 of club-shaped solid laser medium 1a that will be adjacent with partially reflecting mirror 2, as the object plane of the 1st imaging optical system, but the object plane of the 1st imaging optical system is not limited in this.For example, shown in Figure 12 (b), with above-mentioned execution mode 2 in the same manner, for the structure that inner aperture 11 is set in optical resonator, by making inner aperture 11 as the 1st datum level, make its object plane that becomes the 1st imaging optical system, then can access the effect identical with above-mentioned execution mode 2.Different with Figure 12 (b), under the situation of the inner aperture 11 of configuration between club-shaped solid laser medium 1 and the completely reflecting mirror 3, as long as consider with following situation of equal value, promptly, as implement as described in the mode 2, in situation with respect to the inner aperture 11 of position configuration of center 101 symmetries of club-shaped solid laser medium.In addition, if with above-mentioned execution mode 3 in the same manner, the end face 102 of club-shaped solid laser medium 1a that will be adjacent with partially reflecting mirror 2 makes its object plane that becomes the 1st imaging optical system as the 1st datum level, then can obtain the effect identical with above-mentioned execution mode 3.Key is, the position that optical resonator is inner suitable is as the 1st datum level, the object plane of the 1st imaging optical system that setting is formed by relay lens 6 and in conjunction with lens 7, make this object plane in the 1st image planes imaging by relay lens 6, and then by make the 1st image planes on the incident end face 81 of optical fiber 8, become to dwindle the relaying picture in conjunction with lens, simultaneously with the partially reflecting mirror be mid point and with optical resonator on the position of object plane optics symmetry of the 1st imaging optical system set, aperture 5 is set, utilization is by the 2nd imaging optical system that relay lens 6 constitutes, and makes that imaging in conjunction with lens gets final product as the aperture 5 of the object plane of the 2nd imaging optical system.

Execution mode 5

Figure 13 is the schematic diagram of the structure of the club-shaped solid laser device in the expression embodiments of the present invention 5.Adopt so-called MOPA (Master Oscillator PowerAmplifier) structure in the present embodiment, promptly, use 3 club-shaped solid laser medium 1a, 1b, 1c, only the 3rd club-shaped solid laser medium 1c is configured in the optical resonator that is made of partially reflecting mirror 2 and completely reflecting mirror 3, use as lasing exciter, simultaneously, the 1st, the 2nd club-shaped solid laser medium 1a, 1b use as the amplifier that makes the laser amplification of sending in the exciter.In the present embodiment, 3 club-shaped solid laser medium 1a, 1b, 1c are at a distance of 2Lm and uniformly-spaced configuration.And in the middle of the 2nd club-shaped solid laser medium 1b and the 3rd club-shaped solid laser medium 1c, the partially reflecting mirror 2 that configuration is made of level crossing, the 3rd club-shaped solid laser medium 1c is the position of Lm in distance, the completely reflecting mirror 3 that configuration is made of level crossing.Shown in present embodiment, in the club-shaped solid laser device that uses a plurality of club-shaped solid laser media 1, if adopt preiodic type MOPA structure, promptly, the distance of a plurality of club-shaped solid laser media 1 with 2Lm uniformly-spaced disposed, the end face that is configured in terminal club-shaped solid laser medium 1 in distance is a Lm place configuration completely reflecting mirror 3, simultaneously, intermediate configurations partially reflecting mirror 2 at any club-shaped solid laser medium 1, then a plurality of club-shaped solid laser media 1 all by the ideal conditions of equal equal excitations under, with the situation of above-mentioned preiodic type resonator in the same manner, the periodicity of the condition shape in each club-shaped solid laser medium 1 is retained.Thereby, even use the preiodic type MOPA structure shown in the present embodiment, also can use a plurality of club-shaped solid laser media 1, when keeping the optically focused constant, easily realize high-output powerization.About preiodic type MOPA structure, in the club-shaped solid laser device that uses a plurality of club-shaped solid laser media 1 is common structure, as long as the number of the club-shaped solid laser medium 1 that uses in the number of the club-shaped solid laser medium 1 that disposes in the optical resonator and the amplifier is selected according to desired performance.

Below, to present embodiment, promptly the collocation method with respect to the optical system of preiodic type MOPA structure describes.In preiodic type MOPA structure, in end face 102 beginnings of the club-shaped solid laser medium 1a of the terminal section of shoot laser 4, at a distance of the position that 2Lm at interval is 1/2 distance L m that is provided with respect to club-shaped solid laser medium 1a, 1b, 1c, set the 3rd datum level 2 '.With the 3rd datum level 2 ' be mid point, with as i.e. the 2nd datum level place, the position of the interarea symmetry of the thermal lens of equal value 9 of the 1st club-shaped solid laser medium 1a of the 1st datum level, the aperture 5 that has with the diameter opening about equally of club-shaped solid laser medium 1a is set.That is, when setting the 2nd datum level, the 3rd datum level has the effect identical with the partially reflecting mirror of execution mode 1～4, therefore the 3rd datum level is called virtual partially reflecting mirror.Below, with above-mentioned execution mode 1 in the same manner, constitute the 1st imaging optical system by relay lens 6 and in conjunction with lens 7, at first utilize relay lens 6 to make interarea imaging on the 1st image planes 10 of the thermal lens of equal value 9 of club-shaped solid laser medium 1a, simultaneously, utilization makes the 1st image planes 10 become to dwindle the relaying picture on the incident end face 81 of optical fiber 8 in conjunction with lens.On this basis, in the present embodiment, (1) formula shown in the above-mentioned execution mode 1 that can directly be suitable for is to (3).

In cycle MOPA structure, the periodicity of the condition shape in the club-shaped solid laser medium 1 also constant ground keeps, therefore, if utilize the method identical with above-mentioned execution mode 1, configuration aperture 5, relay lens 6, in conjunction with the incident end face 81 of lens 7, optical fiber 8, then not only can obtain the effect identical, and can when keeping the optically focused constant, easily realize high-output powerization with above-mentioned execution mode 1.In addition, if the cycle MOPA structure shown in the more above-mentioned execution mode 4 shown in periodic resonance device structure and the present embodiment, then under the situation of periodic resonance device structure, because all club-shaped solid laser medium 1 all is configured in optical resonator inside, so it is lower to send the ratio of light in the laser of output naturally, and because of the position of the boundary condition beam waist of optical resonator is fixed, so advantage is the easier good laser of optically focused 4 that sends.On the other hand since in optical resonator a plurality of club-shaped solid laser media 1 of configuration, so because of the fluctuation of the energized condition between each club-shaped solid laser medium 1, the stable condition of optical resonator destroys easily, have the shortcoming that unstable oscillation takes place easily.For cycle MOPA structure, because the light that sends naturally that sends from amplifier easily is exaggerated, so the ratio of sending light naturally shared in laser 4 increases, and, since because of the position of the boundary condition beam waist of optical resonator unfixing, so the shortcoming that exists optically focused to reduce easily.In addition, in low intensive laser 4, can not make full use of Amplifier Gain, have the inefficient shortcoming of generation of Laser.On the other hand, under situation about using with the club-shaped solid laser medium 1 of periodic resonance device optical resonator similar number, because the number of the club-shaped solid laser medium 1 that disposes in the optical resonator can reduce, energized condition occurs also can stably producing the advantage of laser 4 under the situation of fluctuation between each club-shaped solid laser medium 1 so have.

In addition, the interarea of thermal lens of equal value 9 of club-shaped solid laser medium 1a that the exit end that will be positioned at laser has been shown in the present embodiment is as the i.e. structure of the object plane of the 1st imaging optical system of the 1st datum level, but the object plane of the 1st imaging optical system is not limited to this.For example if following structure also can access the effect identical with above-mentioned execution mode 3, promptly, with above-mentioned execution mode 3 in the same manner, with virtual partially reflecting mirror 2 ' be mid point, with i.e. the 2nd datum level place, the position of end face 102 symmetries of the club-shaped solid laser medium 1a of the exit end that is positioned at laser, the diameter aperture 5 about equally of configuration opening diameter and club-shaped solid laser medium 1a, simultaneously, is the object plane of the 1st imaging optical system with the end face 102 of club-shaped solid laser medium 1a as the 1st datum level, becomes the relaying picture on the incident end face 81 of optical fiber 8.

In addition, in the above description, show thermal lens of equal value 9 or end face 102 with club-shaped solid laser medium 1a, setting as the 1st datum level is the method for the object plane of the 1st imaging optical system, but the establishing method of the object plane of the 1st imaging optical system is not limited thereto.For example, from the end face 102 of club-shaped solid laser medium 1a in the scope of mid point 101, set thermal lens interarea arbitrarily as benchmark, can access same effect.Key is, with virtual partially reflecting mirror 2 ' be mid point with i.e. the 2nd datum level place, the position of the thermal lens principal plane locations optics symmetry of setting, the diameter aperture 5 about equally of configuration opening diameter and club-shaped solid laser medium 1, use simultaneously by relay lens 6 and the 1st imaging optical system that constitutes in conjunction with lens 7, make the interarea of thermal lens 9 of equal value on the incident end face 81 of optical fiber 8, become the relaying picture, use the 2nd imaging optical system that constitutes by relay lens 6 simultaneously, make aperture 5 imaging in conjunction with lens 7, even thereby change at the thermal lens of club-shaped solid laser medium 1, or laser 4 takes place under the situation of directive property change, beam diameter in conjunction with lens 7 places, light-beam position also keeps constant, guarantee the beam diameter at incident end face 81 places of optical fiber 8 simultaneously, light-beam position, can carry out stable transmitting beam by optical fiber 8, for from optical fiber 8 emitting lasers 4, can keep the optically focused constant simultaneously.

Execution mode 6

Figure 14 (a) is the schematic diagram of the structure of the club-shaped solid laser device in the expression mode 6 of the present invention.In the present embodiment, with above-mentioned execution mode 5 in the same manner, a plurality of club-shaped solid laser medium 1a, 1b, 1c are uniformly-spaced disposed, adopt cycle MOPA structure.In addition, in the present embodiment, in the optical resonator that constitutes by partially reflecting mirror 2 and completely reflecting mirror 3, insert inner aperture 11, with the beam diameter of limit laser 4.Among club-shaped solid laser medium 1b, the 1c that uses as amplifier, only the part passed through of laser 4 is subjected to amplification, and therefore, the condition shape among the 1st club-shaped solid laser medium 1a roughly is retained in amplifier.In the present embodiment, inner aperture 11 is set at apart from partially reflecting mirror 2 and is the position of La.

Below, the collocation method of the optical system in the present embodiment is described.At first with above-mentioned execution mode 5 in the same manner, be the position of Lm at the end face 102 of the club-shaped solid laser medium 1a of the terminal section of distance shoot laser 4, suppose virtual partially reflecting mirror 2 '.Then, will be on the direction of club-shaped solid laser medium 1a the position of the virtual partially reflecting mirror 2 of distance ' be La as the 1st datum level, here be assumed to virtual inner aperture 11 '.Will be with virtual partially reflecting mirror 2 ' be mid point, with the position of virtual inner aperture 11 ' optics symmetry as the 2nd datum level, at this configuration opening diameter and inner aperture 11 aperture 5 about equally.Thereby,, also can be suitable for (11) formula shown in the above-mentioned execution mode 2 for cycle MOPA structure.Below, with above-mentioned execution mode 1 in the same manner, constitute the 1st imaging optical system by relay lens 6 and in conjunction with lens 7, at first make the imaging on the 1st image planes 10 of virtual inner aperture, utilize simultaneously in conjunction with lens 7 to make the 1st image planes 10 on the incident end face 81 of optical fiber 8, become to dwindle the relaying picture by relay lens 6.In addition, relay lens 6 constitutes the 2nd imaging optical system, makes aperture 5 imaging in conjunction with lens by relay lens 6.Thereby, in the present embodiment, also can be suitable for (2) to (3) formula shown in (1 ') formula shown in the above-mentioned execution mode 2, the above-mentioned execution mode 1.

In addition, different with Figure 14 (a), shown in Figure 14 (b), under the situation of the inner aperture 11 of configuration between club-shaped solid laser medium 1c and the completely reflecting mirror 3, can think and following situation equivalence, promptly, as implement as described in the mode 2, in partially reflecting mirror 2 sides,, dispose the situation of inner aperture 11 apart from partially reflecting mirror 2 and above-mentioned completely reflecting mirror 3 same distance places.That is, under the situation of distance completely reflecting mirror 3,, determine that with the configuration identical optical system gets final product with Figure 14 (a) as long as according to shown in Figure 14 (b) for the inner aperture 11 of La place configuration.

Shown in present embodiment, in cycle MOPA structure, as in optical resonator, inserting the mode of inner aperture 11 with the confine optical beam diameter, because the periodicity constant ground of the condition shape in the club-shaped solid laser medium 1 keeps, so not only can obtain the effect identical with above-mentioned execution mode 2, and can when keeping constant optically focused, easily realize high-output powerization.

In addition, in the present embodiment, show and only in optical resonator, insert the structure of inner aperture 11 with the confine optical beam diameter, but also can insert on the basis of the inside aperture 11 in the optical resonator, near the arbitrary club-shaped solid laser medium 1 that uses as amplifier, the aperture of confine optical beam diameter is set.For example, if be provided with virtual inner aperture 11 ' the position, the aperture that opening diameter is substantially equal to the reality of inner aperture 11 is set, the influence of sending amplification light naturally that beam-pointing variation that takes place in the club-shaped solid laser medium that then can suppress to use as amplifier and the beam quality that makes laser 4 worsen, and then can utilize optical fiber 8 to carry out the transmission of the laser 4 of high stability and reliability.

In addition, in the above description, mixed YAG (yttrium-aluminium-garnet) crystallization of Nd (neodymium) of use is described as the structure of club-shaped solid laser medium, but the kind of solid laser medium is not limited to this, for example under the situation of using phosphate glass and vanadate crystal etc., also can obtain same effect.

Industrial applicibility

The club-shaped solid laser device that the present invention relates to, be applicable to use Optical Fiber Transmission laser and The device of processing.

Claims (24)

1. club-shaped solid laser device, it uses relay lens and in conjunction with lens, makes laser from symmetrical stable type optical resonator output to optical fiber input, and this symmetry stable type optical resonator is made of club-shaped solid laser medium and partially reflecting mirror and completely reflecting mirror,

It is characterized in that,

And the mid point club-shaped solid laser medium and above-mentioned partially reflecting mirror opposing end faces and this club-shaped solid laser medium of above-mentioned partially reflecting mirror disposed adjacent between the optional position, set the 1st datum level,

With respect to above-mentioned partially reflecting mirror and with the position of the 1st datum level optics symmetry, set the 2nd datum level,

Above-mentioned relay lens is configured in following position: make the imaging on the 1st image planes of above-mentioned the 1st datum level, make simultaneously above-mentioned the 2nd datum level above-mentioned in conjunction with lens on imaging,

Above-mentioned in conjunction with lens configuration in following position: make the imaging on fiber end face of above-mentioned the 1st image planes.

2. club-shaped solid laser device according to claim 1 is characterized in that,

Suppose the thin lens optically of equal value with thermal lens, principal plane locations place at the thin lens of this supposition sets above-mentioned the 1st datum level, above-mentioned thermal lens be and the mid point club-shaped solid laser medium and above-mentioned partially reflecting mirror opposing end faces and this club-shaped solid laser medium of above-mentioned partially reflecting mirror disposed adjacent between form.

3. club-shaped solid laser device according to claim 1 is characterized in that,

With the club-shaped solid laser medium and the above-mentioned partially reflecting mirror opposing end faces of above-mentioned partially reflecting mirror disposed adjacent, set above-mentioned the 1st datum level.

4. according to any described club-shaped solid laser device in the claim 1 to 3, it is characterized in that,

Position configuration aperture at above-mentioned the 2nd datum level.

5. club-shaped solid laser device according to claim 4 is characterized in that,

The opening diameter of said aperture, with the diameter of above-mentioned club-shaped solid laser medium about equally.

6. club-shaped solid laser device according to claim 1 is characterized in that,

Above-mentioned club-shaped solid laser medium is one.

7. club-shaped solid laser device according to claim 1 is characterized in that,

Above-mentioned club-shaped solid laser medium is a plurality of.

8. club-shaped solid laser device, it uses relay lens and in conjunction with lens, makes laser from the output of stable type optical resonator to optical fiber input, and this stable type optical resonator is made of club-shaped solid laser medium and completely reflecting mirror and level crossing,

It is characterized in that,

Above-mentioned partially reflecting mirror and and the mid point of the club-shaped solid laser medium of above-mentioned partially reflecting mirror disposed adjacent between, in the irrelevant and constant position of thermal lens of the beam diameter and the above-mentioned club-shaped solid laser medium of laser, set the 1st datum level,

With respect to above-mentioned partially reflecting mirror and with the position of the 1st datum level optics symmetry, set the 2nd datum level,

Above-mentioned relay lens is configured in following position: make the imaging on the 1st image planes of above-mentioned the 1st datum level, make simultaneously above-mentioned the 2nd datum level above-mentioned in conjunction with lens on imaging,

Above-mentioned in conjunction with lens configuration in following position: make the imaging on fiber end face of above-mentioned the 1st image planes.

9. club-shaped solid laser device according to claim 8 is characterized in that,

Between above-mentioned club-shaped solid laser medium and above-mentioned partially reflecting mirror, have the inside aperture of confine optical beam diameter,

In the position of this inside aperture, set the 1st datum level.

10. club-shaped solid laser device according to claim 8 is characterized in that,

Between above-mentioned club-shaped solid laser medium and above-mentioned completely reflecting mirror, have the inside aperture of confine optical beam diameter,

From above-mentioned partially reflecting mirror to the club-shaped solid laser side medium, at a distance of and above-mentioned inner aperture and above-mentioned completely reflecting mirror between distance position about equally, be set at the 1st datum level.

11. any described club-shaped solid laser device in 10 is characterized in that according to Claim 8,

Position configuration aperture at above-mentioned the 2nd datum level.

12. club-shaped solid laser device according to claim 11 is characterized in that,

The opening diameter of said aperture and the opening diameter of above-mentioned inner aperture are about equally.

13. any described club-shaped solid laser device in 10 is characterized in that according to Claim 8,

Above-mentioned club-shaped solid laser medium is one.

14. any described club-shaped solid laser device in 10 is characterized in that according to Claim 8,

Above-mentioned club-shaped solid laser medium is a plurality of.

15. club-shaped solid laser device, it has uniformly-spaced a plurality of club-shaped solid laser media of configuration, from being configured in terminal club-shaped solid laser medium, roughly 1/2 place at a distance of the configuration space of club-shaped solid laser medium, the completely reflecting mirror that configuration is made of level crossing, in the position of the approximate midpoint between the club-shaped solid laser medium arbitrarily, the partially reflecting mirror that configuration is made of level crossing, thereby between itself and above-mentioned completely reflecting mirror, constitute optical resonator, use club-shaped solid laser medium outside this optical resonator as amplifier, will amplify, use relay lens and in conjunction with lens from above-mentioned optical resonator emitting laser, make laser to optical fiber input

It is characterized in that,

At end face from the laser emitting side of the club-shaped solid laser medium that is positioned at laser emitting side end, at a distance of roughly 1/2 place of the configuration space of above-mentioned club-shaped solid laser medium, suppose to have virtual partially reflecting mirror,

And the mid point club-shaped solid laser medium and above-mentioned virtual partially reflecting mirror opposing end faces and this club-shaped solid laser medium of above-mentioned virtual partially reflecting mirror disposed adjacent between the optional position, set the 1st datum level,

With respect to above-mentioned virtual partially reflecting mirror and with the position of the 1st datum level optics symmetry, set the 2nd datum level,

Above-mentioned relay lens is configured in following position: make the imaging on the 1st image planes of above-mentioned the 1st datum level, make simultaneously above-mentioned the 2nd datum level above-mentioned in conjunction with lens on imaging,

Above-mentioned in conjunction with lens configuration in following position: make the imaging on fiber end face of above-mentioned the 1st image planes.

16. club-shaped solid laser device according to claim 15 is characterized in that,

Suppose the thin lens optically of equal value with thermal lens, principal plane locations place at the thin lens of this supposition sets above-mentioned the 1st datum level, above-mentioned thermal lens be the club-shaped solid laser medium adjacent with above-mentioned virtual partially reflecting mirror, and above-mentioned virtual partially reflecting mirror opposing end faces and mid point between form.

17. club-shaped solid laser device according to claim 15 is characterized in that,

In the club-shaped solid laser medium adjacent and above-mentioned virtual partially reflecting mirror opposing end faces, set above-mentioned the 1st datum level with above-mentioned virtual partially reflecting mirror.

18. according to any described club-shaped solid laser device in the claim 15 to 17, it is characterized in that,

Position configuration aperture at above-mentioned the 2nd datum level.

19. club-shaped solid laser device according to claim 18 is characterized in that,

The opening diameter of said aperture, with the diameter of above-mentioned club-shaped solid laser medium about equally.

20. club-shaped solid laser device, it has uniformly-spaced a plurality of club-shaped solid laser media of configuration, from being configured in terminal club-shaped solid laser medium, roughly 1/2 place at a distance of the configuration space of club-shaped solid laser medium, the completely reflecting mirror that configuration is made of level crossing, in the position of the approximate midpoint between the club-shaped solid laser medium arbitrarily, the partially reflecting mirror that configuration is made of level crossing, thereby between itself and above-mentioned completely reflecting mirror, constitute optical resonator, use club-shaped solid laser medium outside this optical resonator as amplifier, will amplify, use relay lens and in conjunction with lens from above-mentioned optical resonator emitting laser, make laser to optical fiber input

It is characterized in that,

At end face from the laser emitting side of the club-shaped solid laser medium that is positioned at laser emitting side end, at a distance of roughly 1/2 place of the configuration space of above-mentioned club-shaped solid laser medium, suppose to have virtual partially reflecting mirror,

Above-mentioned virtual partially reflecting mirror and and the mid point of the club-shaped solid laser medium of above-mentioned virtual partially reflecting mirror disposed adjacent between, in the irrelevant and constant position of thermal lens of the beam diameter and the above-mentioned club-shaped solid laser medium of laser, set the 1st datum level,

With respect to above-mentioned virtual partially reflecting mirror and with the position of the 1st datum level optics symmetry, set the 2nd datum level,

Above-mentioned relay lens is configured in following position: make the imaging on the 1st image planes of above-mentioned the 1st datum level, make simultaneously above-mentioned the 2nd datum level above-mentioned in conjunction with lens on imaging,

Above-mentioned in conjunction with lens configuration in following position: make the imaging on fiber end face of above-mentioned the 1st image planes.

21. club-shaped solid laser device according to claim 20 is characterized in that,

Between the club-shaped solid laser medium adjacent and above-mentioned partially reflecting mirror in above-mentioned optical resonator, have the inside aperture of confine optical beam diameter with above-mentioned partially reflecting mirror,

From above-mentioned virtual partially reflecting mirror to the club-shaped solid laser side medium, approximate the position of the distance between above-mentioned inner aperture and the above-mentioned partially reflecting mirror apart, set the 1st datum level.

22. club-shaped solid laser device according to claim 20 is characterized in that,

Between the club-shaped solid laser medium adjacent and above-mentioned completely reflecting mirror in above-mentioned optical resonator, have the inside aperture of confine optical beam diameter with above-mentioned completely reflecting mirror,

From above-mentioned virtual partially reflecting mirror to the club-shaped solid laser side medium, approximate the position of the distance between above-mentioned inner aperture and the above-mentioned completely reflecting mirror apart, set the 1st datum level.

23. according to any described club-shaped solid laser device in the claim 20 to 22, it is characterized in that,

Position configuration aperture at above-mentioned the 2nd datum level.

24. club-shaped solid laser device according to claim 23 is characterized in that,

The opening diameter of said aperture, with the opening diameter of above-mentioned inner aperture about equally.

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