CN115097556B - Dispersive thin film, optical fiber core insert, dispersive cavity mirror, resonant cavity device and laser - Google Patents

Abstract

The present disclosure provides a dispersion film comprising: a plurality of first film layers, the first film layers having a first refractive index; and a plurality of second film layers having a second refractive index; the first film layer and the second film layer are alternately stacked to form a dispersion film; wherein the first refractive index is greater than the second refractive index; the total thickness of the dispersion film is in the micron order; the total thickness of the first film layer is less than the total thickness of the second film layer. The disclosure also provides an optical fiber ferrule, a dispersive cavity mirror with an all-fiber structure, a laser resonant cavity device and a laser.

Description

Dispersion film, fiber ferrule, dispersion cavity mirror, resonant cavity device and laser

technical field

The present disclosure relates to the technical fields of optical thin films and ultrafast lasers, and particularly relates to a dispersion film, an optical fiber ferrule, a dispersion cavity mirror, a laser resonant cavity device, and a laser.

Background technique

Ultrafast lasers with a repetition rate of GHz have important applications in the fields of special material processing, multiphoton fluorescence imaging, high-speed optical communication systems, and astronomical optical frequency combs.

In terms of special material processing, based on the "ablation cooling" mechanism, using this light source can obtain higher processing accuracy; in terms of two-photon imaging, using this light source can improve imaging resolution to obtain clearer microscopic images; in astronomy In the field of detection, the light source has high single-tooth power, which can improve the measurement accuracy. At present, high repetition rate lasers based on gain media of solid/crystal materials have the advantages of high repetition rate and narrow pulse width. In comparison, all-fiber lasers have unique advantages such as good heat dissipation, stable mode, and stable environment, and are more suitable for application in some specific environments. However, high-repetition fiber lasers still face the "bottleneck" of wide pulse widths that are difficult to compress. "question.

The pulse width of the 5GHz Yb-doped fiber laser reported in 2017 was 2.6ps; the corresponding pulse width of the 3GHz Yb-doped fiber laser reported in 2018 was 3.4ps; the pulse width tested in the 12.5GHz Yb-doped fiber laser reported in 2019 was 1.9ps ps.

It can be seen that although the pulse output of GHz repetition rate is realized in these all-fiber lasers, the corresponding pulse width is concentrated in the ps level, which limits the application of this type of light source in the above-mentioned fields to a certain extent. The reason for this "bottleneck" problem is that according to the mode-locking principle, in order to obtain a pulse output with a repetition rate of GHz level, the cavity length of the laser resonator should be shortened to the order of centimeters. The short cavity length makes the commonly used dispersion management Chirped mirror pairs, chirped gratings, etc. cannot be installed in the cavity due to volume reasons, so it is difficult to implement dispersion management in such a short cavity to achieve wide spectrum and narrow pulse laser output.

Some studies have also made other attempts, such as coating the dispersion management film on the lens and inserting it into the above-mentioned fiber laser resonator, and introducing additional devices to achieve spatial optical coupling, which leads to the loss of the laser's all-fiber structure, and the system becomes Complex and unstable.

Contents of the invention

In order to solve at least one of the above technical problems, the present disclosure provides a dispersion film, a fiber ferrule, a dispersion cavity mirror, a laser resonator device, and a laser.

According to one aspect of the present disclosure, there is provided a dispersion film, comprising:

a plurality of first film layers, the first film layers having a first refractive index;

a plurality of second film layers having a second refractive index;

The first film layer and the second film layer are stacked alternately to form the dispersion film;

Wherein, the first refractive index is greater than the second refractive index;

The total thickness of the dispersion film is on the order of microns;

The total thickness of the first film layer is smaller than the total thickness of the second film layer.

According to the dispersion film according to at least one embodiment of the present disclosure, the first film layer is preferably one of Ta ₂ O ₅ , Nb ₂ O ₅ , and HfO ₂ , and the second film layer is preferably SiO ₂ .

According to the dispersion film according to at least one embodiment of the present disclosure, the odd-numbered layers are the first film layer, the even-numbered layers are the second film layer, and both the bottom layer and the top layer of the dispersion film are the first film layer.

According to at least one embodiment of the present disclosure, the total thickness of the dispersion film is 7.803 μm to 8.292 μm, the first film layer is Ta ₂ O ₅ , and the second film layer is SiO ₂ ;

The total number of layers of the first film layer and the second film layer is 45 layers;

From the bottom layer to the top layer, the corresponding film thickness of each film layer is:

132-141nm, 244-252nm, 141-152nm, 194-201nm, 136-155nm, 203-212nm, 145-173nm, 210-220nm, 138-148nm, 197-207nm, 130-140nm, 192-202nm,129- 136nm, 173-202nm, 134-144nm, 205-207nm, 140-163nm, 204-216nm, 132-144nm, 220-228nm, 169-179nm, 217-227nm, 141-158nm, 202-204nm, 127-138nm, 197-207nm, 139-142nm, 204-208nm, 135-145nm, 200-210nm, 135-145nm, 211-212nm, 153-167nm, 235-245nm, 137-144nm, 188-201nm, 136-156nm, 202- 212nm, 147-163nm, 223-229nm, 144-154nm, 196-206nm, 131-141nm, 275-285nm, 160-171nm.

According to the dispersion film in at least one embodiment of the present disclosure, the dispersion film is disposed on the end surface of the fiber ferrule through the first film layer as a bottom layer.

According to the dispersion film according to at least one embodiment of the present disclosure, the shapes of the first film layer and the second film layer are both disc shapes, and the radial dimension of the first film layer is the same as that of the second film layer. The radial dimensions of the layers are the same.

According to the dispersion film in at least one embodiment of the present disclosure, the alternate stacking of multiple first film layers and multiple second film layers is realized based on plasma sputtering.

According to another aspect of the present disclosure, a fiber optic ferrule is provided, including:

An optical fiber ferrule body, the optical fiber ferrule body has a first end and a second end, the first end forms an end face, and the second end is used for inserting an optical fiber;

According to any one embodiment of the present disclosure, the dispersion film is arranged on the end surface of the optical fiber ferrule body.

According to the optical fiber ferrule according to at least one embodiment of the present disclosure, the end surface of the optical fiber ferrule body and the dispersion film have matching shapes.

In the optical fiber ferrule according to at least one embodiment of the present disclosure, the end face is a ground and polished end face.

According to the fiber optic ferrule in at least one embodiment of the present disclosure, the fiber optic ferrule body is made of ceramic material.

According to yet another aspect of the present disclosure, a dispersive cavity mirror with an all-fiberized structure is provided, including:

The optical fiber ferrule of any embodiment of the present disclosure;

A passive optical fiber, the passive optical fiber is inserted into the optical fiber ferrule body through the second end of the optical fiber ferrule body.

According to yet another aspect of the present disclosure, a laser resonator device is provided, including:

a first ferrule having a first end and a second end, the first end of the first ferrule forming an end face;

a second ferrule, the second ferrule has a first end and a second end, the first end of the second ferrule is docked with the first end of the first ferrule;

a third ferrule, the third ferrule has a first end and a second end, the first end of the third ferrule forms an end face;

a dispersion film, the dispersion film is disposed on the end surface of the first ferrule;

a gain fiber, the two ends of the gain fiber are respectively inserted into the second end of the second ferrule and the second end of the third ferrule;

a semiconductor saturable absorber mirror, the semiconductor saturable absorber mirror is disposed on the end face of the third ferrule;

Wherein, the dispersion film is the dispersion film of any embodiment of the present disclosure.

According to the laser resonator device of at least one embodiment of the present disclosure, the length of the gain fiber is less than or equal to 10 cm, and the fiber core of the gain fiber is doped with rare earth ions to achieve short fiber length, that is, optical gain that meets the mode-locking threshold Require.

According to the laser resonator device in at least one embodiment of the present disclosure, when the length of the gain fiber is less than or equal to 3 cm, the third ferrule is canceled, the second end of the second ferrule forms an end face, and the semiconductor A saturable absorbing mirror is disposed on the end face of the second ferrule.

In the laser cavity device according to at least one embodiment of the present disclosure, the gain fiber is a single-mode fiber, a polarization-maintaining single-mode fiber, a multimode fiber or a double-clad fiber.

In the laser cavity device according to at least one embodiment of the present disclosure, the gain fiber is a fiber doped with one kind of rare earth ions or a co-doped fiber with more than two kinds of rare earth ions.

According to the laser cavity device according to at least one embodiment of the present disclosure, the rare earth ions are Yb ³⁺ , Er ³⁺ , Tm ³⁺ or Ho ³⁺ .

The laser cavity device according to at least one embodiment of the present disclosure further includes:

a passive optical fiber inserted into the second end of the first ferrule.

The laser cavity device according to at least one embodiment of the present disclosure further includes:

a ceramic sleeve, the ceramic sleeve is partially sleeved on the first ferrule and partially sleeved on the second ferrule, so as to fix the first ferrule and the second ferrule docking.

According to yet another aspect of the present disclosure, a laser is provided, including the dispersive cavity mirror with an all-fiber structure according to any one embodiment of the present disclosure.

According to still another aspect of the present disclosure, a laser is provided, including the laser resonator device in any one embodiment of the present disclosure.

Description of drawings

The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure, are included to provide a further understanding of the disclosure, and are incorporated in and constitute this specification. part of the manual.

FIG. 1 is a schematic structural view of a dispersion film according to an embodiment of the present disclosure.

FIG. 2 shows a fiber ferrule and a dispersive cavity mirror with an all-fiberized structure according to an embodiment of the present disclosure.

FIG. 3 is a schematic structural diagram of a laser resonator device according to an embodiment of the present disclosure.

FIG. 4 is a transmittance curve diagram of the dispersive cavity mirror in Embodiment 1 of the present disclosure.

FIG. 5 is a graph of the transmittance of the dispersive cavity mirror when the thickness is adjusted in Embodiment 1 of the present disclosure.

FIG. 6 is a spectrum diagram of a 1 GHz femtosecond laser obtained in Embodiment 1 of the present disclosure.

FIG. 7 is an autocorrelation curve of a 1 GHz femtosecond laser obtained in Embodiment 1 of the present disclosure.

FIG. 8 is a spectrum diagram of a 2.2 GHz femtosecond laser obtained in Example 2 of the present disclosure.

FIG. 9 is an autocorrelation graph of the 2.2 GHz femtosecond laser obtained in Embodiment 2 of the present disclosure.

FIG. 10 is a spectrum diagram of a 3.3 GHz femtosecond laser obtained in Example 3 of the present disclosure.

FIG. 11 is an autocorrelation curve of the 3.3 GHz femtosecond laser obtained in Embodiment 3 of the present disclosure.

FIG. 12 is a time-domain pulse diagram of a 3.3 GHz femtosecond laser obtained in Embodiment 3 of the present disclosure.

Detailed ways

The present disclosure will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific implementation manners described here are only used to explain relevant content, rather than to limit the present disclosure. It should also be noted that, for ease of description, only parts related to the present disclosure are shown in the drawings.

It should be noted that, in the case of no conflict, the implementation modes and the features in the implementation modes in the present disclosure can be combined with each other. The technical solutions of the present disclosure will be described in detail below with reference to the accompanying drawings and in combination with implementation manners.

Unless otherwise specified, the illustrated exemplary embodiments/embodiments are to be understood as exemplary features providing various details of some manner in which the technical idea of the present disclosure can be implemented in practice. Therefore, unless otherwise stated, the features of various embodiments/embodiments may be additionally combined, separated, interchanged, and/or rearranged without departing from the technical concept of the present disclosure.

The use of cross-hatching and/or shading in the figures is generally used to clarify the boundaries between adjacent features. As such, unless stated otherwise, the presence or absence of cross-hatching or shading conveys or indicates no specific material, material properties, dimensions, proportions, commonality between the illustrated components, and/or any other characteristic of the components, Any preferences or requirements for attributes, properties, etc. Also, in the drawings, the size and relative sizes of components may be exaggerated for clarity and/or descriptive purposes. While exemplary embodiments may be implemented differently, a specific process sequence may be performed in an order different from that described. For example, two consecutively described processes may be performed substantially simultaneously or in an order reverse to that described. In addition, the same reference numerals denote the same components.

When an element is referred to as being "on" or "over", "connected to" or "coupled to" another element, the element may be directly on, directly connected to, or Or directly bonded to the other component, or intermediate components may be present. However, when an element is referred to as being "directly on," "directly connected to," or "directly coupled to" another element, there are no intervening elements present. To this end, the term "connected" may refer to a physical connection, an electrical connection, etc., with or without intervening components.

For descriptive purposes, this disclosure may use terms such as "under", "beneath", "below", "under", "above", "on", "on" ... above", "higher" and "side (e.g., in "side walls")", etc., to describe the relationship between one component and another (other) component as shown in the drawings relation. Spatially relative terms are intended to encompass different orientations of the device in use, operation and/or manufacture in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of "above" and "beneath". In addition, the device may be otherwise positioned (eg, rotated 90 degrees or at other orientations), and as such, the spatially relative descriptors used herein are interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms "a" and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. In addition, when the terms "comprising" and/or "comprising" and their variants are used in this specification, it means that the stated features, integers, steps, operations, parts, components and/or their groups exist, but do not exclude One or more other features, integers, steps, operations, parts, components and/or groups thereof are present or in addition. Note also that, as used herein, the terms "substantially," "about," and other similar terms are used as terms of approximation and not as terms of degree, and as such, they are used to explain what one of ordinary skill in the art would recognize. Inherent deviations from measured, calculated and/or supplied values.

FIG. 1 is a schematic structural view of a dispersion film according to an embodiment of the present disclosure.

Referring to Fig. 1, the dispersion film of the present disclosure includes:

a plurality of first film layers, the first film layer has a first refractive index;

a plurality of second film layers, the second film layers have a second refractive index;

the first film layer and the second film layer are alternately stacked to form a dispersion film;

Wherein, the first refractive index is greater than the second refractive index;

The total thickness of the dispersion film is in the order of microns;

The total thickness of the first film layer is smaller than the total thickness of the second film layer.

The dispersion film of the present disclosure has the functions of dispersion and dichromatic light separation through the above structural design.

Referring to Fig. 1, the dispersion film of the present disclosure can be arranged on the end face of the optical fiber ferrule, and the end face is used _as the base, and the first film and the second film are alternately arranged. In Fig. 1, _Ta2O5 is used as the first film, and SiO ₂ As the second film, the dispersion film of the preferred embodiment of the present disclosure was formed.

In some embodiments of the present disclosure, the first film layer can also be Nb ₂ O ₅ , HfO ₂ , etc., those skilled in the art under the inspiration of the technical solution of the present disclosure, the material of the first film layer and the second film layer The selection/adjustment of materials all fall within the protection scope of the present disclosure.

In FIG. 1 , the white film layer represents the first film layer (high refractive index film layer Ta ₂ O ₅ ), and the black film layer represents the second film layer (low refractive index film layer SiO ₂ ).

Referring to FIG. 1 , preferably, the odd-numbered layers of the dispersion film of the present disclosure are the first film layer, the even-numbered layers are the second film layer, and both the bottom layer and the top layer of the dispersion film are the first film layer.

For the dispersion film of the present disclosure, preferably, both the first film layer and the second film layer are in the shape of a disk, and the radial dimension of the first film layer is the same as that of the second film layer.

Referring to FIG. 1 , the dispersion film of the present disclosure can be disposed on the end face of the fiber ferrule through the first film layer as the bottom layer.

The dispersion thin film of the present disclosure can realize alternate stacking of a plurality of first film layers and a plurality of second film layers based on a plasma sputtering method.

For the dispersion film of the present disclosure, based on the central wavelength of the dispersion film to be obtained and the specific requirements of group velocity delay dispersion, the dispersion amount, reflectivity, and bandwidth target value parameters can be set, and then the first film layer and the second film layer The material, the number of layers, and the distribution of the film layer are set according to the thickness.

Referring to FIG. 1 , preferably, the total thickness of the dispersion film of the present disclosure is 7.803 μm to 8.292 μm, the first film layer is Ta ₂ O ₅ , and the second film layer is SiO ₂ ;

The total number of layers of the first film layer and the second film layer is 45 layers;

From the bottom layer to the top layer, the corresponding film thickness of each film layer is:

132-141nm, 244-252nm, 141-152nm, 194-201nm, 136-155nm, 203-212nm, 145-173nm, 210-220nm, 138-148nm, 197-207nm, 130-140nm, 192-202nm,129- 136nm, 173-202nm, 134-144nm, 205-207nm, 140-163nm, 204-216nm, 132-144nm, 220-228nm, 169-179nm, 217-227nm, 141-158nm, 202-204nm, 127-138nm, 197-207nm, 139-142nm, 204-208nm, 135-145nm, 200-210nm, 135-145nm, 211-212nm, 153-167nm, 235-245nm, 137-144nm, 188-201nm, 136-156nm, 202- 212nm, 147-163nm, 223-229nm, 144-154nm, 196-206nm, 131-141nm, 275-285nm, 160-171nm.

Wherein, the total thickness of the first film layer is 3.211-3.499 μm, and the total thickness of the second film layer is 4.592-4.793 μm.

The dispersion film shown in Figure 1 has the following optical properties: the transmittance T>80% of the film to the pump light wavelength 973-980nm, and the reflectance R>60% to the signal light wavelength, in the wavelength range of 1010-1080nm, the group velocity Dispersion <-800fs ² .

Figure 4 and Figure 5 are the transmittance curves corresponding to the fine-tuning of the film thickness within the range of a single film thickness.

If only the dichroic light-splitting function of the dispersion film of the present disclosure is used, it can be used as an incident cavity mirror constituting a laser resonator to construct an all-fiber resonator structure; if only the dispersion management function is used, it can be used as a dispersion control element in an optical system .

FIG. 2 shows the structure of a dispersive cavity mirror with an all-fiberized structure according to an embodiment of the present disclosure. Also shown in FIG. 2 is a fiber optic ferrule.

Referring to FIG. 2 , the fiber optic ferrule of the present disclosure includes: a fiber optic ferrule body 200 and a dispersion film 100 .

Wherein, the fiber ferrule body 200 has a first end and a second end, the first end forms an end face, and the second end is used for inserting the optical fiber 300; the dispersion film 100 is the dispersion film of any embodiment described above in the present disclosure, and the dispersion The film 100 is disposed on the end face of the fiber optic ferrule body 200 .

Preferably, the end face of the fiber ferrule body 200 and the dispersion film 100 have matching shapes.

Wherein, preferably, the end face of the first end of the fiber optic ferrule body 200 is a ground and polished end face.

The material of the fiber ferrule body 200 of the fiber ferrule described in the present disclosure is preferably a ceramic material.

In some embodiments of the present disclosure, the coating fixture for fixing the fiber ferrule body can be made, so that it can be adapted to the operating platform of the coating machine to prepare a dispersion film on the end face of the fiber ferrule body, and can also be fixed on the fiber optic ferrule body. The fiber optic ferrule body described in this article.

In the process of preparing the dispersion film 100 on the end face of the fiber ferrule body 200 based on plasma sputtering, the thickness of each layer of the dispersion film can be controlled by coating time so that the thickness error of each film layer is less than 0.5nm.

Among them, the thickness error and non-uniformity in the plasma sputtering coating process can be corrected by controlling the distance between the target and the end face of the fiber ferrule body, the sputtering angle, and combining the mask.

Preferably, the dispersive cavity mirror with an all-fiberized structure of the present disclosure includes: the fiber ferrule and the passive optical fiber 300 in any of the above-mentioned embodiments.

Referring to FIG. 2 , the passive optical fiber 300 is inserted into the fiber ferrule body 200 through the second end of the fiber ferrule body 200 .

FIG. 3 shows a laser resonator device according to an embodiment of the present disclosure, including:

The first ferrule 201, the first ferrule 201 has a first end (right end) and a second end (left end), the first end of the first ferrule 201 forms an end face (right end in FIG. 3 );

The second ferrule 202, the second ferrule 202 has a first end (left end) and a second end (right end), the first end of the second ferrule 202 is docked with the first end of the first ferrule 201;

The third ferrule 203, the third ferrule 203 has a first end (right end) and a second end (left end), the first end of the third ferrule 203 forms an end face;

Dispersion film 100, the dispersion film 100 is arranged on the above-mentioned end surface of the first ferrule 201;

A gain fiber 400, the two ends of the gain fiber 400 are respectively inserted into the second end of the second ferrule 202 and the second end of the third ferrule 203;

a semiconductor saturable absorption mirror 600, the semiconductor saturable absorption mirror 600 is arranged on the above-mentioned end surface of the third ferrule 203;

Wherein, the dispersion film 100 is the dispersion film 100 of any embodiment described above in the present disclosure.

Preferably, the length of the gain fiber 400 of the laser resonator device of the present disclosure is less than or equal to 10 cm, and the fiber core of the gain fiber 400 is doped with rare earth ions to achieve a short fiber length that meets the optical gain requirement of the mode-locking threshold.

Wherein, the gain fiber 400 may be a single-mode fiber, a polarization-maintaining single-mode fiber, a multi-mode fiber, or a double-clad fiber.

The rare earth ions described above can be one of Yb ³⁺ , Er ³⁺ , Tm ³⁺ , Ho ³⁺ or a co-doped form.

In some embodiments of the present disclosure, when the length of the gain fiber is less than or equal to 3 cm, the third ferrule 203 is canceled, the second end of the second ferrule 202 forms an end face, and the semiconductor saturable absorbing mirror 600 is arranged on the second ferrule. The end face of the core 202.

The gain fiber of the present disclosure may be a fiber doped with one kind of rare earth ions or a co-doped fiber doped with more than two kinds of rare earth ions. Under the enlightenment of the technical solution of the present disclosure, those skilled in the art can select/adjust the type of gain fiber 400 and the type of doped rare earth ions, all of which fall within the protection scope of the present disclosure.

Preferably, referring to FIG. 3 , the laser resonator device of the present disclosure further includes a passive optical fiber 300 inserted into the second end of the first ferrule 201 .

In some embodiments of the present disclosure, the laser resonator device of the present disclosure, referring to FIG. 3 , further includes a ceramic sleeve 500. The ceramic sleeve 500 is partially sleeved on the first on the second ferrule 202 to fix the connection between the first ferrule 201 and the second ferrule 202 .

It can be known from the above description that based on the dispersion film 100 of the present disclosure, a high repetition frequency femtosecond fiber laser resonator device can be constructed.

The laser generated by the laser resonator device of the present disclosure is output out of the cavity through a wavelength division multiplexer (not shown) fused to the passive optical fiber 300 .

Prism pair dechirping can be implemented outside the cavity to obtain ultra-narrow pulse output.

Referring to FIG. 3 , the cavity mirror based on the dispersion film of the present disclosure can be fixed and connected through a peripheral sleeve (ie, the ceramic sleeve 500 described above), compatible with the ultrafast fiber resonator, and maintains the full fiberization of the laser resonator structure.

The laser resonator device of the present disclosure, in the 1 μm wave band, based on the overall structure of all-fiber, can realize the laser output of the following indicators: the pulse repetition frequency is 1 GHz, the shortest pulse width is 364 fs, and the mode-locked spectrum line width is 7.6 nm. Laser output; the pulse repetition frequency is 2.2GHz, the shortest pulse width is 283fs, the pulse laser output of the mode-locked spectrum linewidth is 8.25nm; the repetition frequency is 3.3GHz, the shortest pulse width is 266fs, the mode-locked spectrum linewidth is 9.6nm Pulse laser output.

In addition, the laser resonator device disclosed in the present disclosure can not only realize laser pulse output with repetition frequency above 1 GHz in centimeter-level ultrashort resonator, but also greatly improve the stability of laser output.

Through the structural design of the unique dispersion film described above in the present disclosure, it exhibits certain optical properties and can be applied to high repetition frequency femtosecond fiber laser resonators. The dispersion film of the present disclosure is applied to the end face of an optical fiber ferrule for the first time, and has both the functions of group velocity delay dispersion and dichromatic light splitting.

Compared with the large-size glass substrate in the prior art, the dispersion film of the present disclosure is applied to the laser resonator, which can maintain the overall all-fiber structure of the resonator, improve the reliability and stability of femtosecond laser operation, and is especially suitable for For applications requiring high stability such as laser surgery.

The size of the laser resonant cavity device disclosed in the present disclosure is on the order of centimeters, which helps to improve the integration of fiber lasers.

The present disclosure also provides a laser. In some embodiments of the present disclosure, the laser of the present disclosure includes a dispersive cavity mirror with an all-fiber structure in any one of the embodiments of the present disclosure (refer to FIG. 2 ). In other embodiments of the present disclosure, the laser of the present disclosure includes the laser resonator device of any one of the embodiments of the present disclosure (refer to FIG. 3 ).

The dispersion film, fiber ferrule, dispersion cavity mirror, laser resonator device and laser of the present disclosure will be described below in conjunction with more specific embodiments.

Embodiment one

First, load and fix the passive optical fiber Hi1060 of the American Corning Company in the nano-zirconia ferrule. The cross-sectional shape of the end face of the ferrule is circular, the inner diameter is 125 μm, and the outer diameter is 2.5 mm. Further, the end face of the ferrule is ground and polished. deal with.

Taking the end face of the ferrule as the base, starting from the base, the first layer of high-refractive index film layer Ta ₂ O ₅ , the second layer of low-refractive index film layer SiO ₂ , the third layer of high-refractive index film layer Ta ₂ O ₅ , the second layer of Four layers of low refractive index film SiO ₂ , fifth layer of high refractive index film layer Ta ₂ O ₅ , sixth layer of low refractive index film layer SiO ₂ , seventh layer of high refractive index film layer Ta ₂ O ₅ , eighth layer Low refractive index film layer SiO ₂ , ninth high refractive index film layer Ta ₂ O ₅ , tenth low refractive index film layer SiO ₂ , eleventh high refractive index film layer Ta ₂ O ₅ , twelfth layer Low-refractive index film layer SiO ₂ , thirteenth high-refractive-index film layer Ta ₂ O ₅ , fourteenth low-refractive-index film layer SiO ₂ , fifteenth high-refractive index film layer Ta ₂ O ₅ , tenth Six layers of low-refractive index SiO ₂ , seventeenth high-refractive-index Ta ₂ O ₅ , eighteenth low-refractive-index SiO ₂ , nineteenth high-refractive index Ta ₂ O ₅ , The twentieth low-refractive index film layer SiO ₂ , the twenty-first high-refractive index film layer Ta ₂ O ₅ , the twenty-second low-refractive index film layer SiO ₂ , the twenty-third high-refractive index film layer Ta ₂ O ₅ , the twenty-fourth low-refractive index film layer SiO ₂ , the twenty-fifth high-refractive index film layer Ta ₂ O ₅ , the twenty-sixth low-refractive index film layer SiO ₂ , the twenty-seventh High refractive index layer Ta ₂ O ₅ , twenty-eighth low refractive index layer SiO ₂ , twenty-ninth high refractive index layer Ta ₂ O ₅ , thirtieth low refractive index layer SiO ₂ , the thirty-first layer of high refractive index film layer Ta ₂ O ₅ , the thirty-second layer of low refractive index film layer SiO ₂ , the thirty-third layer of high refractive index film layer Ta ₂ O ₅ , the thirty-fourth layer of low Refractive index film layer SiO ₂ , thirty-fifth high-refractive index film layer Ta ₂ O ₅ , thirty-sixth low-refractive index film layer SiO ₂ , thirty-seventh high-refractive index film layer Ta ₂ O ₅ , Thirty-eighth low-refractive index film layer SiO ₂ , thirty-ninth high-refractive index film layer Ta ₂ O ₅ , fortieth low-refractive index film layer SiO ₂ , forty-first high-refractive index film layer Ta ₂ O ₅ , the forty-second low-refractive index film layer SiO ₂ , the forty-third high-refractive index film layer Ta ₂ O ₅ , the forty-fourth low-refractive index film layer SiO ₂ , the forty-fifth High refractive index film layer Ta ₂ O ₅ , the film thickness corresponding to each film layer is 132-141nm, 244-252nm, 141-152nm, 194-201nm, 136-155nm, 203-212nm, 145-173nm, 210nm -220nm, 138-148nm, 197-207nm, 130-140nm, 192-202nm, 129-136nm, 173-202nm, 134-144nm, 205-207nm, 140-163nm, 204-216nm, 132-144nm, 220-228nm , 169-179nm, 217-227nm, 141-158nm, 202-204nm, 127-138nm, 197-207nm, 139-142nm, 204-208nm, 135-145nm, 200-210nm, 135-145nm, 211-212nm, 153nm -167nm, 235-245nm, 137-144nm, 188-201nm, 136-156nm, 202-212nm, 147-163nm, 223-229nm, 144-154nm, 196-206nm, 131-141nm, 275-285nm, 160-171nm .

Make a coating fixture for fixing the ferrule, so that it can be adapted to the operating platform of the coating machine, and can also fix the above-mentioned polished ferrule.

A multi-layer film with alternating Ta ₂ O ₅ and SiO ₂ phases was prepared by plasma sputtering. The thickness of the film is controlled by time, and the thickness error of each film layer of the multilayer film is less than 0.5nm. Thickness errors and inhomogeneities in the sputtering coating process are corrected by controlling the distance between the target and the end face of the fiber and the sputtering angle, combined with a special mask.

The optical properties of the dispersion film of this embodiment are: the group delay dispersion at 1040 nm is -761 fs ² . The transmittance to 974nm pump light is 99%, and the reflectance to signal light 1040nm is 89.3%.

The dispersion film of this embodiment can be used to construct a high repetition frequency femtosecond fiber laser resonator. Referring to FIG. Through the ceramic sleeve 500, the dispersion film 100 is connected to the end face of the second ferrule 202, so as to ensure low-loss transmission of light.

This embodiment uses commercial Yb-doped quartz gain fiber 400, the first end of which is plugged into the second ferrule 202, the second end of the gain fiber 400 is plugged into the third ferrule 203, and the end face of the third ferrule 203 is saturable with the semiconductor The absorbing mirror 600 is butted. In this embodiment, epoxy resin is used to bond the semiconductor saturable absorbing mirror 600 to the end face of the third ferrule 203 . The modulation depth of the semiconductor saturable absorbing mirror 600 in this embodiment is 5%, the saturation flux is 40 μJ/cm ² , and the recovery time is 1 ps. The length of the gain fiber 400 in this embodiment is 9.8 cm, and the end surfaces of all the ferrules in this embodiment are mirror polished.

Further connect the pump source through a wavelength division multiplexer to construct a high repetition frequency femtosecond laser with a wide spectrum and narrow pulse width, and use a semiconductor laser pump source with a wavelength of 974nm to excite the resonator of this embodiment, and the pump light passes through a single Mode fiber output, the highest pump light power is 680mW. Use a fiber optic fusion splicer to weld the pigtail of the pump source to the pump end of the 980nm/1040nm fiber-optic wavelength division multiplexer, and connect the common end of the wavelength division multiplexer to the dispersion cavity of the resonant cavity of the present disclosure The mirror pigtail 300 is welded. Under pump excitation, the generated laser light is output out of the cavity through the dispersive cavity mirror pigtail 300 and the signal end of the wavelength division multiplexer. Then use the transmission-type diffraction grating pair to perform extra-cavity dechirp, and the following technical effects can be obtained:

While realizing the basic repetition frequency 1GHz pulse laser output in the 1μm band, the 3dB linewidth and pulse width of the mode-locked spectrum are 7.6nm and 364fs respectively, and the entire laser resonator is an all-fiber structure, and the mode-locked spectrum and pulse width are self-contained. The relevant trajectories are shown in Figure 6 and Figure 7, respectively. In addition, compared with the research reported in the prior art, the mode-locked pulsed laser output by the resonator of this embodiment has two typical features: 1) better flatness at the top of the spectrum; 2) higher stability of laser operation.

It can be found that the all-fiberized structure of the femtosecond laser resonator can be maintained by using the dispersion film of the present disclosure. Moreover, the constructed laser is light and compact, easy to scale production and integration.

Embodiment two

Using the method for preparing the dispersion film described above, a dispersive cavity mirror with optical characteristics of -348fs ² near 1033nm, 99% transmittance to 974nm pump light, and 89.6% reflectance to signal light 1033nm was prepared.

Based on the dispersive cavity mirror of this embodiment, a femtosecond laser cavity with a higher repetition rate can be constructed. Continue to refer to Fig. 3, present embodiment uses commercial Yb-doped quartz gain fiber 400, and its first end inserts the second ferrule 202, the second end of gain fiber 400 inserts the 3rd ferrule 203, the 3rd ferrule 203 The end face is connected to the semiconductor saturable absorbing mirror 600 , and epoxy resin is used in this embodiment to bond the semiconductor saturable absorbing mirror 600 to the end face of the third ferrule 203 . The modulation depth of the semiconductor saturable absorbing mirror 600 in this embodiment is 5%, the saturation flux is 40 μJ/cm ² , and the recovery time is 1 ps. The length of the gain fiber 400 in this embodiment is 4.4 cm, and the end faces of all the ferrules in this embodiment are mirror polished.

Further connect the pump source through a wavelength division multiplexer to construct a high repetition frequency femtosecond laser with a wide spectrum and narrow pulse width, and use a semiconductor laser pump source with a wavelength of 974nm to excite the resonator of this embodiment, and the pump light passes through a single Mode fiber output, the highest pump light power is 680mW. Splice the pump source pigtail with the pump end of the 980nm/1030nm fiber-optic wavelength division multiplexer with an optical fiber fusion splicer, and connect the common end pigtail of the wavelength division multiplexer with the dispersion cavity mirror tail of the resonant cavity of this embodiment Fiber 300 is welded. Under pump excitation, the generated laser light is output out of the cavity through the dispersive cavity mirror pigtail 300 and the signal end of the wavelength division multiplexer. Then use the transmission-type diffraction grating pair to perform extra-cavity dechirp, and the following technical effects can be obtained:

While realizing the basic repetition frequency of 2.2GHz pulse laser output in the 1μm band, the 3dB linewidth and pulse width of the mode-locked spectrum are 8.3nm and 283fs respectively, and the entire laser resonator is an all-fiber structure, and the mode-locked spectrum and pulse width are perfect The autocorrelation trajectories are shown in Figure 8 and Figure 9, respectively. In addition, compared with the research reported in the prior art, the mode-locked pulsed laser output by the resonator of this embodiment has two typical features: 1) better flatness at the top of the spectrum; 2) higher stability of laser operation.

Embodiment three

Using the preparation method of the dispersion film described above, a dispersion cavity mirror with optical characteristics of -233fs ² near 1030nm, 99% transmittance to 974nm pump light, and 89.2% reflectance to signal light 1030nm was prepared.

The dispersion film of this embodiment can be used to construct a high repetition frequency femtosecond fiber laser resonator. Referring to FIG. Through the ceramic sleeve 500, the dispersion film 100 is connected to the end face of the second ferrule 202, so as to ensure low-loss transmission of light.

This embodiment uses commercial Yb-doped quartz gain fiber 400, the first end of which is plugged into the second ferrule 202, the second end of the gain fiber 400 is plugged into the third ferrule 203, and the end face of the third ferrule 203 is saturable with the semiconductor The absorbing mirror 600 is butted. In this embodiment, epoxy resin is used to bond the semiconductor saturable absorbing mirror 600 to the end face of the third ferrule 203 . The modulation depth of the semiconductor saturable absorbing mirror 600 in this embodiment is 5%, the saturation flux is 40 μJ/cm ² , and the recovery time is 1 ps. The length of the gain fiber 400 in this embodiment is 3.0 cm, and the end surfaces of all the ferrules in this embodiment are mirror polished.

Further connect the pump source through a wavelength division multiplexer to construct a high repetition frequency femtosecond laser with a wide spectrum and narrow pulse width, and use a semiconductor laser pump source with a wavelength of 974nm to excite the resonator of this embodiment, and the pump light passes through a single Mode fiber output, the highest pump light power is 680mW. Use a fiber optic fusion splicer to weld the pigtail of the pump source to the pump end of the 980nm/1030nm fiber-optic wavelength division multiplexer, and connect the common end of the wavelength division multiplexer to the dispersion cavity mirror tail of the above resonant cavity Fiber 300 is welded. Under pump excitation, the generated laser light is output out of the cavity through the dispersive cavity mirror pigtail 300 and the signal end of the wavelength division multiplexer. Then use the transmission-type diffraction grating pair to perform extra-cavity dechirp, and the following technical effects can be obtained:

In the 1μm band, not only can wide spectrum and narrow pulse output be achieved in the pulsed laser with a higher repetition rate of 3.3GHz, the widest spectral 3dB line width is 9.6nm, and the narrowest pulse width is 266fs. At the same time, the entire laser realizes an all-fiber structure. Fig. 10 is a test spectrum diagram of the laser of this embodiment, the spectrum 3dB linewidth is 9.6nm, Fig. 11 is an autocorrelation locus diagram, the pulse width of the test is 266fs. The pulse sequence tested by the oscilloscope is shown in FIG. 12 , which shows that the laser of this embodiment operates in a DC mode-locked state, and the basic repetition frequency of the pulse is 3.3 GHz.

Embodiment Four

In order to further improve the environmental stability of the laser and build a laser resonator with a full polarization-maintaining structure, in this embodiment, the dispersion film is arranged on the end face of the ceramic ferrule that loads and fixes the polarization-maintaining optical fiber. The Hi1060 optical fiber of Corning Corporation of the United States in the above embodiment is replaced by the PM980 optical fiber of Nufern Corporation. Then, the dispersion film was prepared using the preparation method described above.

When using the polarization-maintaining dispersion cavity mirror of this embodiment to construct a laser resonator cavity, the tail fiber of the semiconductor laser pump source with a wavelength of 974nm is replaced with a PM980 optical fiber, and the wavelength division multiplexer is replaced with a polarization-maintaining type wavelength division The multiplexer and wavelength division multiplexer pigtails are all PM980 optical fibers. The gain fiber uses polarization-maintaining single-mode fiber or double-clad fiber. The remaining components and structures of the resonator remain unchanged as shown in Figure 3. Utilizing the resonant cavity structure of this embodiment, in addition to realizing the GHz repetition frequency ultrafast laser with wide spectrum and narrow pulse width, the whole system is a polarization-maintaining all-fiber structure, which improves the anti-interference ability of the laser and expands its performance under extreme conditions. use.

Embodiment five

In the above-mentioned embodiments, the Yb ³⁺ doped gain fiber is mainly used as the gain medium. In this embodiment, the type of the gain fiber can be further changed in the resonant cavity, such as Er ³⁺ , Tm ³⁺ , Ho ³⁺ , etc. Or co-doped rare earth ions in the optical fiber, correspondingly adjusting the parameters and types of semiconductor saturable absorbing mirrors, all fall within the protection scope of the present disclosure.

In the description of this specification, descriptions referring to the terms "one embodiment/mode", "some embodiments/modes", "examples", "specific examples" or "some examples" mean that the embodiments/modes or The specific features, structures, materials or features described in the examples are included in at least one embodiment/mode or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment/mode or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments/modes or examples in an appropriate manner. In addition, those skilled in the art may combine and combine different embodiments/modes or examples and features of different embodiments/modes or examples described in this specification without conflicting with each other.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

It should be understood by those skilled in the art that the above-mentioned embodiments are only for clearly illustrating the present disclosure, rather than limiting the scope of the present disclosure. For those skilled in the art, other changes or modifications can be made on the basis of the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims (18)

1. A dispersion film, comprising:

a plurality of first film layers, the first film layers having a first refractive index; and

a plurality of second film layers, the second film layers having a second refractive index;

the first film layers and the second film layers are alternately stacked to form the dispersion film;

wherein the first refractive index is greater than the second refractive index;

the total thickness of the dispersion film is in the micron level;

the total thickness of the first film layer is smaller than the total thickness of the second film layer;

wherein the odd layer is a first film layer, the even layer is a second film layer, and the bottom layer and the top layer of the dispersion film are both the first film layer;

the total thickness of the dispersion film is 7.803 μm to 8.292 μm;

the first film layer is Ta ₂ O ₅ 、Nb ₂ O ₅ 、HfO ₂ One of the second film layer is SiO ₂ ；

The total number of layers of the first film layer and the second film layer is 45;

from bottom to top, the rete thickness that each rete corresponds respectively is:

132-141nm、244-252nm、141-152nm、194-201nm、136-155nm、203-212nm、145-173nm、210-220nm、138-148nm、197-207nm、130-140nm、192-202nm、129-136nm、173-202nm、134-144nm、205-207nm、140-163nm、204-216nm、132-144nm、220-228nm、169-179nm、217-227nm、141-158nm、202-204nm、127-138nm、197-207nm、139-142nm、204-208nm、135-145nm、200-210nm、135-145nm、211-212nm、153-167nm、235-245nm、137-144nm、188-201nm、136-156nm、202-212nm、147-163nm、223-229nm、144-154nm、196-206nm、131-141nm、275-285nm、160-171nm；

the transmittance T of the dispersion film to the wavelength 973-980nm of the pumping light is more than 80%.

2. The dispersion film according to claim 1, wherein the dispersion film is provided on an end face of an optical fiber ferrule through the first film layer as a bottom layer.

3. The dispersion film of claim 1, wherein the first film layer and the second film layer are both wafer-shaped in shape, and the radial dimension of the first film layer is the same as the radial dimension of the second film layer.

4. The dispersive film according to claim 1, wherein the alternating stacking of the plurality of first film layers and the plurality of second film layers is achieved by a plasma-based sputtering method.

5. An optical fiber ferrule, comprising:

the optical fiber connector comprises an optical fiber connector body, a first connecting rod and a second connecting rod, wherein the optical fiber connector body is provided with a first end and a second end, the first end forms an end face, and the second end is used for inserting an optical fiber; and

the dispersive film of any one of claims 1 to 4 disposed on the end face of the fiber stub body.

6. The fiber stub of claim 5, wherein the end face of the fiber stub body has a matching shape with the dispersion film.

7. The optical fiber ferrule of claim 5, wherein the end face is an abraded polished end face.

8. A dispersive endoscope having an all-fiber structure, comprising:

the optical fiber ferrule of any one of claims 5 to 7; and

and the passive optical fiber is inserted into the optical fiber ferrule body through the second end of the optical fiber ferrule body.

9. A laser resonator device comprising:

a first ferrule having a first end and a second end, the first end of the first ferrule forming an end face;

a second ferrule having a first end and a second end, the first end of the second ferrule interfacing with the first end of the first ferrule;

a third ferrule having a first end and a second end, the first end of the third ferrule forming an end face;

a dispersion film disposed on the end face of the first ferrule;

the two ends of the gain optical fiber are respectively inserted into the second end of the second inserting core and the second end of the third inserting core; and

a semiconductor saturable absorber mirror disposed on the end face of the third ferrule;

wherein the dispersion film is the dispersion film according to any one of claims 1 to 4.

10. The laser resonator device according to claim 9, wherein the length of the gain fiber is 10cm or less, and the fiber core of the gain fiber is doped with rare earth ions, so as to realize that the optical gain requirement of the mode locking threshold is met when the length of the short fiber is short.

11. The laser resonator device according to claim 9, characterized in that when the length of the gain fiber is 3cm or less, the third ferrule is eliminated, the second end of the second ferrule forms an end face, and the semiconductor saturable absorber mirror is disposed on the end face of the second ferrule.

12. The laser resonator device according to claim 9, wherein the gain fiber is a single mode fiber, a polarization maintaining single mode fiber, a multimode fiber, or a double clad fiber.

13. The laser resonator device according to claim 12, characterized in that the gain fiber is a fiber doped with one kind of rare earth ion or a co-doped form fiber doped with two or more kinds of rare earth ions.

14. The laser resonator device according to claim 13, wherein the rare earth ion is Yb ³⁺ 、Er ³⁺ 、Tm ³⁺ Or Ho ³⁺ 。

15. The laser resonator device of claim 9 further comprising:

a passive optical fiber inserted into the second end of the first ferrule.

16. The laser resonator device of claim 9 further comprising:

the ceramic sleeve is partially sleeved on the first inserting core and partially sleeved on the second inserting core so as to fix the butt joint of the first inserting core and the second inserting core.

17. A laser comprising the dispersive cavity mirror with all-fiber architecture of claim 8.

18. A laser comprising a laser resonator device as claimed in any one of claims 9 to 16.

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