阅读说明：本技术 一种基于ws2的可饱和吸收体的制备方法 (Based on WS2Preparation method of saturable absorber ) 是由 杨慧苒 李旭鹏 赵峰 李璐 王利强 杜恭贺 于 2021-07-27 设计创作，主要内容包括：本发明公开了一种基于WS-(2)的可饱和吸收体的制备方法,解决了现有技术无法掌控WS-(2)纳米片在微光纤上的分布、制备过程复杂且成功率低的问题,包括步骤：1)制备WS-(2)/PMMA薄膜,将分离的WS-(2)/PMMA薄膜转移至去离子水；2)标准单模光纤中间加热,两端拉制后的单模光纤包括原径段和微光纤段；3)将拉制后的单模光纤固定在干净的载玻片上,潜入浸泡有WS-(2)/PMMA薄膜的去离子水中,又捞起,使WS-(2)/PMMA薄膜包覆于微光纤段上,WS-(2)/PMMA薄膜长度方向垂直于单模光纤轴线；WS-(2)/PMMA薄膜经干燥后,将覆盖有WS-(2)/PMMA薄膜的单模光纤在丙酮溶液中腐蚀掉PMMA；单模光纤从载玻片上挑起,WS-(2)薄膜断裂,WS-(2)薄膜包裹在微光纤段表面,得到具有可饱和吸收体器件。(The invention discloses a method based on WS 2 The preparation method of the saturable absorber solves the problem that the prior art cannot control WS 2 The problems of complicated distribution and preparation processes of the nano sheets on the micro optical fiber and low success rate comprise the following steps: 1) preparation of WS 2 PMMA film, WS to isolate 2 Transferring the PMMA film to deionized water; 2) heating the middle of a standard single-mode optical fiber, wherein the single-mode optical fiber with two ends drawn comprises an original diameter section and a micro optical fiber section; 3) fixing the drawn single mode fiber on a clean glass slide, submerging the single mode fiber in the glass slide with the WS 2 The PMMA film is fished up again in deionized water, so that WS is 2 Coating a PMMA film on a micro-fiber section, WS 2 The length direction of the PMMA film is vertical to the axis of the single-mode optical fiber; WS 2 The PMMA film is dried and covered with WS 2 Etching PMMA off the single-mode optical fiber of the PMMA film in an acetone solution; lifting a single mode fiber from a glass slide, WS 2 Film breakage, WS 2 The film is wrapped on the surface of the micro-fiber section to obtain the device with the saturable absorber。)

1. Based on WS₂The method for preparing the saturable absorber is characterized in that: the method comprises the following steps:

1) preparation of WS₂PMMA film

Preparation of WS₂PMMA film, WS to isolate₂Transferring the PMMA film into deionized water for cleaning;

2) preparation of micro-fiber segment

The middle of the standard single-mode fiber is heated by hydrogen flame, and two ends of the standard single-mode fiber are drawn, the drawn single-mode fiber comprises a left original diameter section and a right original diameter section and a middle deformed micro-fiber section, the micro-fiber section comprises a middle section and a conical section connected with the left original diameter section and the right original diameter section, and the axial dimension of the middle section is smaller than WS₂Width of PMMA film;

3) preparation of saturable absorber device

3.1) fixing the drawn single-mode fiber on a clean glass slide, and then submerging the glass slide with the WS soaked in the glass slide₂In deionized water of a PMMA film;

3.2) bringing WS₂The PMMA film is positioned above the drawn single-mode optical fiber, so that WS is ensured to be dragged out of deionized water when the glass slide is dragged out of the deionized water₂The PMMA film covers the middle section of the micro-optical fiber section and the part of the conical section close to the middle section;

3.3) scooping the slide out of the deionized water, WS₂The PMMA film is coated on the middle section of the micro-fiber section and the partial conical section near the middle section, and WS₂The length direction of the PMMA film is vertical to the axis of the single-mode optical fiber after being drawn;

3.4) waiting for WS₂After the PMMA film is fully dried, the film is covered with WS₂Placing the single-mode fiber of PMMA film in acetone solution until WS₂The PMMA on the surface of the PMMA film is corroded;

3.5) gently raising the single mode fiber from the slide, WS₂Film breakage during lifting, WS₂And the film is wrapped on the surface of the micro-fiber section to obtain the device with the saturable absorber.

2. A substrate according to claim 1In WS₂The method for preparing the saturable absorber is characterized in that: the step 1) comprises the following steps:

1.1) growing WS on a sapphire substrate by chemical vapor deposition₂A thin film sample, wherein the sapphire substrate has a length of 10 +/-1 mm and a width of 0.2-0.3 mm;

1.2) in WS₂Coating a layer of PMMA solution on the surface of the film sample, and curing the PMMA solution to form a film to form the sapphire/WS₂PMMA sample;

1.3) sapphire/WS₂Putting PMMA sample into KOH solution, and then putting sapphire substrate and WS₂Separating PMMA film;

1.4) slide WS on glass₂The PMMA film was transferred from KOH solution to deionized water until WS₂And cleaning the residual KOH solution on the surface of the PMMA film.

3. WS-based according to claim 1 or 2₂The method for preparing the saturable absorber is characterized in that: in step 3.4) WS₂After the PMMA film is fully dried, the method also comprises the following heating steps: to WS₂Heating the PMMA film wrapped micro-optical fiber section until WS₂The gap between the PMMA film and the glass slide is not reduced.

4. WS-based according to claim 3₂The method for preparing the saturable absorber is characterized in that: in the step 3.5), a probe is adopted to gently lift the micro-fiber section from the glass slide; the probe is prepared by heating a standard single-mode optical fiber through flame and rapidly breaking the standard single-mode optical fiber.

Technical Field

The invention relates to a preparation method of a saturable absorber, in particular to a preparation method based on transition metal sulfide (WS)₂) A practical method for producing a saturable absorber.

Background

The passive mode-locking fiber laser is an effective method for generating ultrashort pulses, and has great application value in the industrial field, basic research and other aspects. In a passively mode-locked fiber laser, a saturable absorber is a key device. The nonlinear polarization rotation technology and the nonlinear amplification ring mirror technology and other similar saturable absorbers are widely applied to passive mode-locked lasers, but the mode-locked lasers based on the two technologies have strict requirements on the polarization state in a cavity, the change of the surrounding environment greatly disturbs the lasers, and the stable output of mode-locked pulses is difficult to realize. The influence of environmental change on the laser can be overcome to a certain extent by adopting a true saturable absorber, such as carbon nano tube, graphene, black phosphorus and the like, so as to obtain stable pulse output, and particularly, in recent years, a two-dimensional transition metal sulfide material such as tungsten disulfide (WS)₂) Has been intensively studied and is considered to be a saturable absorber material with great potential for development.

At present, based on WS₂The preparation method of the saturable absorber mainly comprises the following steps:

1) let WS be₂And the transmission type saturable absorber is arranged between the two optical fiber connectors. Due to direct penetration of laser beam in cavity to WS₂Easily cause WS₂Thermal damage, and therefore the saturable absorber prepared by the method is not beneficial to generating high-energy mode-locking pulses.

2) Let WS be₂The thin film is attached to the D-shaped area of the D-shaped optical fiber to manufacture a saturable absorber. Saturable absorber manufactured based on methodThe interaction between the optical evanescent potential field and the material is weaker and the optical polarization state is sensitive.

3) Let WS be₂The nanosheet solution is deposited in the tapered region of the microfiber by an optical deposition method to prepare a saturable absorber device. WS could not be controlled by this preparation method₂The distribution of the nano-sheets on the micro-fiber leads to uncontrollable optical performance of the prepared saturable absorber.

Also based on WS₂The preparation method of the saturable absorber mainly comprises the following steps:

1) preparation of WS on sapphire substrate by Chemical Vapor Deposition (CVD)₂A PMMA film; sapphire substrate and WS using potassium hydroxide (KOH) solution₂Separating PMMA film and transferring to glass slide;

2) placing the glass slide on a three-dimensional moving platform, and placing the WS under a microscope₂Cutting the PMMA film into a plurality of strip films with the length of 100um and the width of about 30 um;

3) heating a standard single-mode fiber by hydrogen flame to draw a micro fiber, and fixing the micro fiber on a glass slide;

4) placing a probe on a three-dimensional moving platform, using the probe to lift one strip-shaped film, and paving the film in a conical area of a micro optical fiber under a microscope;

5) etching off PMMA on the surface of the film by using acetone, and slightly lifting the micro-optical fiber from the glass slide by using a probe, thereby realizing WS₂And (3) wrapping the micro optical fiber by the film.

However, the method needs the cooperation of a three-dimensional moving system and a microscope with a large depth of field to cut the film into micron size, so that the method has high requirements on experimental instruments, complex preparation process and low success rate.

Disclosure of Invention

To solve existing WS-based₂Uncontrollable WS by saturable absorber preparation method₂The problems of high distribution and experiment requirements of the nano-sheets on the micro-optical fiber, complex preparation process and low success rate are solved, and the WS is provided₂A method for preparing a film-wrapped micro-fiber saturable absorber.

The technical scheme adopted by the invention is as follows:

based on WS₂The preparation method of the saturable absorber is characterized in that: the method comprises the following steps:

1) preparation of WS₂PMMA film

Preparation of WS₂PMMA film, WS to isolate₂Transferring the PMMA film into deionized water for cleaning;

2) preparation of micro-fiber segment

The middle of the standard single-mode fiber is heated by hydrogen flame, and two ends of the standard single-mode fiber are drawn, the drawn single-mode fiber comprises a left original diameter section and a right original diameter section and a middle deformed micro-fiber section, the micro-fiber section comprises a middle section and a conical section connected with the left original diameter section and the right original diameter section, and the axial dimension of the middle section is smaller than WS₂Width of PMMA film; the middle section is a part between the left conical section and the right conical section, and the average diameter of the middle section is the smallest relative to the conical sections, and the axial size of the middle section can be close to 0;

3) preparation of saturable absorber device

3.1) fixing the drawn single-mode fiber on a clean glass slide, and then submerging the glass slide with the WS soaked in the glass slide₂In deionized water of a PMMA film;

3.2) bringing WS₂The PMMA film is positioned above the drawn single-mode optical fiber, so that WS is ensured to be dragged out of deionized water when the glass slide is dragged out of the deionized water₂The PMMA film covers the middle section of the micro-optical fiber section and the conical section close to part of the middle section;

3.3) scooping the slide out of the deionized water, WS₂The PMMA film is coated on the middle section of the micro-fiber section and the partial conical section near the middle section, and WS₂The length direction of the PMMA film is vertical to the axis of the single-mode optical fiber after being drawn;

3.4) waiting for WS₂After the PMMA film is fully dried, the film is covered with WS₂Placing the single-mode fiber of PMMA film in acetone solution until WS₂The PMMA on the surface of the PMMA film is corroded;

3.5) gently lifting the single mode fiber from the glass slide,let WS be₂Film breakage during lifting, WS₂And the film is wrapped on the surface of the micro-fiber section to obtain the device with the saturable absorber.

Further, the step 1) comprises the following steps:

1.1) growing WS on a sapphire substrate by chemical vapor deposition₂A thin film sample, wherein the sapphire substrate has a length of 10 +/-1 mm and a width of 0.2-0.3 mm;

1.2) in WS₂Coating a layer of PMMA solution on the surface of the film sample, and curing the PMMA solution to form a film to form the sapphire/WS₂PMMA sample;

1.3) sapphire/WS₂Putting PMMA sample into KOH solution, and then putting sapphire substrate and WS₂Separating PMMA film;

1.4) slide WS on glass₂The PMMA film was transferred from KOH solution to deionized water until WS₂And cleaning the residual KOH solution on the surface of the PMMA film.

Further, in step 3.4) WS₂After the PMMA film is fully dried, the method also comprises the following heating steps: to WS₂Heating the PMMA film wrapped micro-optical fiber section until WS₂The gap between the PMMA film and the glass slide is not reduced.

Further, in the step 3.5), the micro optical fiber section is gently lifted from the glass slide by using a probe; the probe is prepared by heating a standard single-mode optical fiber through flame and rapidly breaking the standard single-mode optical fiber.

The invention has the beneficial effects that:

1. in the prior art, the film needs to be cut in a micron order so as to accurately wrap the middle section of the micro-fiber section and reduce the loss of the saturable absorber. According to the invention, micron-scale cutting of the film is not required, the film with the corresponding size can be directly used only by selecting the proper size of the sapphire substrate, and most of redundant film is left on the glass slide in the final breaking process, so that the overlapping area is reduced. Therefore, although the loss of the saturable absorber is increased due to the fact that the micro-optical fiber section is wrapped by the large-size film, the method does not need a three-dimensional moving platform and a microscope with a large depth of field, and does not need micron-scale cutting on the film, so that the preparation difficulty is reduced, the product percent of pass is greatly improved, and the user requirements are met.

2. The preparation method of the saturable absorber provided by the invention innovatively utilizes WS₂The film and the heater are heated to enhance the adhesion between the film and the glass slide, and the film is not easy to wash away when the PMMA film is dissolved in the subsequent acetone solution; in addition, the heating reduces the gap between the film and the glass slide, and the overlapping area of the film when the film wraps the micro optical fiber can be reduced to the maximum extent. Therefore, the method effectively realizes the full-surface wrapping of the micro-optical fiber by the material, increases the contact area between the material and the optical evanescent field, reduces the loss of the saturable absorber to the maximum extent, improves the laser damage resistance threshold, and further improves the output power of the pulse laser.

Drawings

FIG. 1 is a schematic flow chart of step 1) according to an embodiment of the present invention;

FIG. 2 shows WS in step 3) according to an embodiment of the present invention₂Schematic diagram of PMMA film 10 covering the micro-fiber section;

FIG. 3 shows WS in an embodiment of the present invention₂A schematic illustration of the wrapping of the film 1 to the micro-fiber;

in the figure: 1-WS₂Film, 2-sapphire substrate, 3-PMMA film, 4-KOH solution, 5-deionized water, 6-glass slide, 7-original diameter section, 8-adhesive tape, 9-micro optical fiber section and 10-WS₂A PMMA film.

Detailed Description

In order to more clearly explain the technical solution of the present invention, the following detailed description of the present invention is made with reference to the accompanying drawings and specific examples.

The WS₂The preparation method of the film-wrapped micro-optical fiber saturable absorber comprises the following steps:

1) preparation of WS₂PMMA film

As shown in FIG. 1, a sapphire substrate 2 (having a size of 10X 0.2 mm) was formed by Chemical Vapor Deposition (CVD)²) Overgrowth WS₂Film sample 1, at WS₂Spin-coating a layer of polymethyl methacrylate (PMMA) solution on the surface of the film sample; standing at room temperature for 4 hours to solidify PMMA into a film, and forming the sapphire/WS with a three-layer laminated structure₂PMMA sample, PMMA film 3 as protective medium, preventing WS₂The film 1 is damaged in the subsequent processing; mixing sapphire/WS₂Placing the PMMA sample into a potassium hydroxide KOH solution 4, standing for 24 hours at normal temperature, and then placing the sapphire substrate 2 and WS₂Separating PMMA film; slide the WS on a glass slide₂The PMMA film was transferred from KOH solution 4 to deionized water 5, left for 30 minutes and WS was again transferred₂The PMMA film was transferred to clean deionized water 5, left for 30 minutes, and this was repeated 4 times to ensure that WS was transferred₂Cleaning the residual KOH solution on the surface of the PMMA film;

2) preparation of micro-fiber segment

Heating the middle of a standard single-mode fiber by hydrogen flame, and drawing two ends of the standard single-mode fiber, wherein the drawn single-mode fiber comprises a left original diameter section 7 and a right original diameter section 7 and a middle deformed micro-fiber section, and the micro-fiber section comprises a middle section and a conical section connected with the left original diameter section and the right original diameter section; the middle section has a smallest average diameter of 2-4 μm and an axial dimension smaller than WS₂Width of PMMA film;

3) preparation of saturable absorber device

As shown in FIG. 2, the original diameter section 7 is fixed to a clean glass slide 6 with an adhesive tape 8 so that the drawn single mode optical fiber is fixed to the clean glass slide, and the glass slide 6 is submerged in step 1) to be soaked with WS₂Moving the slide glass 6 left and right in deionized water 5 of PMMA film to adjust the micro-fiber section and WS₂Relative position of PMMA film 10, WS₂The PMM film is arranged above the single-mode fiber after drawing, and the middle section and the WS of the micro-fiber section are moved slowly₂The middle position of the PMMA film 10 is substantially opposite to it, and WS₂The PMMA film 10 has a length direction perpendicular to the axis of the micro-fiber section, and then the glass slide 6, WS, is slowly fished up from the deionized water 5₂The PMMA film 10 is coated on the middle section of the micro optical fiber section and the partial conical section close to the middle section; placing the scooped slide 6In the air, let WS₂The PMMA film enwraps the micro-optical fiber section for natural evaporation for about 2 hours until WS₂the/PMMA film 10 is dried thoroughly and then covered with WS₂Placing the single-mode fiber of PMMA film on a heater, heating at 150 ℃ for 30 minutes to reduce WS₂The gap between the PMMA film 10 and the glass slide 6 is not reduced until the gap is no longer reduced, which increases WS₂Adhesion between the PMMA film 10 and the glass slide 6; covering the WS with₂Placing the single-mode fiber of PMMA film in acetone solution for two minutes, WS₂The PMMA film 10 surface PMMA is etched, then the micro optical fiber section is slightly lifted from the glass slide 6 by the probe, WS is lifted in the process of lifting₂Film 1 breaks and due to the effect of the suction force, WS is achieved as shown in FIG. 3₂The film 1 wraps the middle section and the conical section close to the middle section to obtain the WS-based film₂The saturable absorber of (1), wherein the probe used is prepared by flame heating a standard single mode optical fiber and rapidly pulling it apart.

The saturable absorber device adopting the preparation method has the advantages that:

1) the insertion loss is small: when the diameter of the micro optical fiber section is 2 μm, the low loss requirement of the saturable absorption device can be still ensured;

2) high photodamage threshold: the saturable absorber device prepared by the method greatly increases the optical damage threshold of the saturable absorber device by utilizing the interaction between the evanescent potential field of light and the material;

3) the action area of light and materials is large: the method can realize WS₂The film wraps the micro-fiber, makes full use of the effective area of the micro-fiber, enhances the light and WS₂Interaction of the thin films.

The above description is only for the purpose of describing the preferred embodiments of the present invention and is not intended to limit the technical solutions of the present invention, and any known modifications made by those skilled in the art based on the main technical concepts of the present invention are within the technical scope of the present invention.