WO2018205087A1

WO2018205087A1 - Heterojunction saturable absorption mirror and preparation method therefor, and pulse fiber laser

Info

Publication number: WO2018205087A1
Application number: PCT/CN2017/083438
Authority: WO
Inventors: 闫培光; 陈浩; 邢凤飞
Original assignee: 深圳大学
Priority date: 2017-05-08
Filing date: 2017-05-08
Publication date: 2018-11-15

Abstract

A heterojunction saturable absorption mirror (100) and a preparation method therefor, and a pulse fiber laser. The heterojunction saturable absorption mirror (100) comprises a substrate (101), a gold film layer (102) covering the substrate (101), and an atomic hierarchical two-dimensional material film covering the gold film layer (102). The atomic hierarchical two-dimensional material film comprises an atomic hierarchical two-dimensional material slow saturable absorber heterojunction thin film (103), an isolation material (104) and an atomic hierarchical two-dimensional material fast saturable absorber heterojunction thin film (105) which are successively arranged. The heterojunction saturable absorption mirror (100) forms an atomic hierarchical two-dimensional heterojunction saturable absorption mirror (100) by means of alternately stacking different two-dimensional atomic hierarchical materials, and in combination with excellent characteristics of a two-dimensional laminated material itself, the regulation and control over the nonlinear characteristic of a saturable absorber is realized.

Description

Heterojunction saturable absorption mirror and preparation method thereof, pulsed fiber laser

Technical field

The invention belongs to the field of laser technology, and in particular relates to a heterojunction saturable absorption mirror, a preparation method thereof and a pulsed fiber laser.

Background technique

The use of passive mode-locking technology is an effective way to achieve ultra-fast pulse output of fiber lasers, and the key technology of passive mode-locking is the need for saturable absorption in fiber laser resonators. At present, researchers have used a variety of saturable absorption effects to obtain passive mode-locked ultrafast pulse outputs in fiber lasers. In general, in order to overcome the shortcomings of fiber laser mode-locking environment instability, researchers often use semiconductor saturable absorption mirrors (SESAM) to achieve fiber laser mode-locked ultra-fast pulse output.

However, commercial SESAM is expensive, complicated in fabrication process, narrow in saturation absorption bandwidth, generally supports only picosecond pulse output, and has a low damage threshold, so it is not suitable for omnidirectional research on the dynamics of ultrafast fiber lasers. characteristic. Therefore, the development of a low-cost, simple process, high-performance saturable absorber has always been the goal pursued in the field of ultrafast laser physics.

technical problem

The technical problem to be solved by the present invention is to provide a heterojunction saturable absorption mirror, a preparation method thereof, and a pulsed fiber laser to solve the problem that the commercial SESAM used in the prior art is expensive, complicated in manufacturing process, and low in reliability. defect.

Technical solution

The present invention is achieved by a heterojunction saturable absorption mirror comprising a substrate, a gold film layer overlying the substrate, and an atom overlying the gold film layer Layer two-dimensional material film;

The atomic-level two-dimensional material film comprises an atomic-level two-dimensional material slow-saturated absorber heterojunction film, an isolating material and an atomic-level two-dimensional material fast saturable absorber heterojunction film.

Further, the atomic level two-dimensional material heterojunction saturable absorption mirror further comprises a package protection layer, the package protection layer covering the atomic layer two-dimensional material film; the package protection layer is hexagonal boron nitride .

Further, the gold film layer has a thickness of 30 to 300 nm.

Further, the atomic level two-dimensional material slow saturable absorber heterojunction film includes at least one of molybdenum disulfide, molybdenum diselenide, zirconium diselenide, zirconium disulfide, tin disulfide, and tin diselenide. Kind.

Further, the atomic-level two-dimensional material fast saturable absorber heterojunction film comprises graphene, tungsten disulfide, tungsten diselenide, tungsten disulfide, molybdenum disulfide, antimony disulfide, antimony diselenide At least one of bismuth selenide, bismuth disulfide, and indium selenide.

The invention also provides a preparation method of a heterojunction saturable absorption mirror, comprising the following steps:

Placing the substrate and the gold target in a vacuum chamber;

The surface of the gold target is ionized to generate a plasma of gold, and the plasma of the gold is deposited on the substrate by magnetron sputtering deposition to form a gold film layer; by controlling deposition time and/or deposition temperature Bringing the gold film layer to a desired thickness;

An atomic-level two-dimensional material is transferred onto the gold film layer to form an atomic-level two-dimensional material film, and a heterojunction saturable absorption mirror is obtained.

Further, the preparation method further includes:

The heterojunction saturable absorption mirror is encapsulated using hexagonal boron nitride to obtain a package protective layer.

The present invention also provides a pulsed fiber laser comprising a sequentially connected semiconductor pump laser, an optical wavelength division multiplexer, a gain fiber, an optical coupler, an optical isolator, an optical circulator, and the like The heterojunction saturable absorption mirror, and the optical circulator is connected to the optical wavelength division multiplexer to form an annular cavity structure; wherein the optical isolator is used to isolate the mode-locked laser, and only the lock is allowed a post-mode laser is unidirectionally outputted within the pulsed fiber laser;

The pump light generated by the semiconductor pump laser is coupled to the gain fiber through the optical wavelength division multiplexer to generate a laser pulse required for mode locking and amplify the laser pulse;

The optical coupler outputs a portion of the amplified laser pulse to the outside of the cavity and another portion to the optical circulator, and the laser pulse entering the optical circulator is coupled into the heterojunction. The saturation absorption mirror performs mode locking, and the mode-locked laser pulse is returned to the optical wavelength division multiplexer via the optical circulator, and then amplified by the gain fiber and then outputted by the optical coupler. laser.

Further, the pulsed fiber laser further includes a polarization controller located between the optical isolator and the optical circulator for controlling a polarization state of laser light in the annular cavity.

The present invention also provides a pulsed fiber laser comprising a sequentially connected semiconductor pump laser, an optical wavelength division multiplexer, a Bragg grating, a gain fiber, and the heterojunction saturable absorption mirror described above ;

The pump light generated by the semiconductor pump laser is coupled by an optical wavelength division multiplexer into a Bragg grating, which is transmitted through the Bragg grating and then enters the gain fiber to generate a laser pulse. The heterojunction saturable absorption mirror locks the laser pulse. The laser pulse after the mode-locking is returned to the gain fiber along the original path for amplification, and the amplified laser pulse is transmitted through the Bragg grating and then output by the optical wavelength division multiplexing laser.

Beneficial effect

Compared with the prior art, the present invention has the beneficial effects that the heterojunction saturable absorption mirror provided by the embodiment of the present invention is alternately superposed by different two-dimensional atomic level materials to form a two-dimensional material heterojunction at the atomic level. Mirror, this new type of saturable absorption mirror can combine the excellent characteristics of the two-dimensional layered material itself, and realize the regulation of the band gap of the saturated absorbing material by using the heterojunction structure. At the same time, the specific two-dimensional material alternately superimposed structure can realize The fast and slow saturable absorber cascades to control the nonlinear characteristics (satutable modulation depth, saturated light intensity, etc.) of the saturable absorber.

DRAWINGS

1 is a schematic structural view of a heterojunction saturable absorption mirror according to a first embodiment of the present invention;

2 is a schematic structural diagram of a pulsed fiber laser according to a third embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a pulsed fiber laser according to a fourth embodiment of the present invention.

Embodiments of the invention

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to FIG. 1, a first embodiment of the present invention provides a heterojunction saturable absorption mirror 100 comprising a substrate 101, a gold film layer 102 overlying the substrate 101, and an atomic level two-dimensional layer overlying the gold film layer 102. Material film

The atomic level two-dimensional material film comprises an atomic level two-dimensional material slow saturable absorber heterojunction film 103, an isolating material 104 and an atomic level two-dimensional material fast saturable absorber heterojunction film 105.

In the heterojunction saturable absorption mirror 100 provided by the first embodiment of the present invention, the atomic-level two-dimensional material film refers to a two-dimensional material film having a thickness of a single atomic layer, which is alternately superposed by using different two-dimensional atomic level materials. A two-dimensional heterojunction saturable absorption mirror is formed at the atomic level. This new saturable absorption mirror can combine the excellent properties of the two-dimensional layered material itself, and the heterojunction structure can be used to control the band gap of the saturated absorbing material. At the same time, the specific two-dimensional material alternately superimposed structure can realize the cascade of fast and slow saturable absorbers, and realize the regulation of the nonlinear characteristics (satutable modulation depth, saturated light intensity, etc.) of the saturable absorber.

Specifically, the substrate 101 is silicon or silicon carbide. The spacer material 104 is a single layer or a plurality of layers of hexagonal boron nitride. Hexagonal boron nitride is a wide-bandgap semiconductor material, which is used as an isolation material between an atomic-level two-dimensional material slow-saturated absorber heterojunction film and an atomic-level two-dimensional material fast-saturated absorber heterojunction film. Avoid the interaction of the two materials.

Specifically, the atomic level two-dimensional material heterojunction saturable absorption mirror 100 further includes a package protection layer 106 overlying the atomic level two-dimensional material film; the package protection layer 106 is hexagonal boron nitride. The function of the encapsulation protective layer 106 is to encapsulate the outermost layer of the heterojunction saturable absorption mirror 100 with an atomic layer of hexagonal boron nitride, so that the heterojunction saturable absorption mirror 100 is isolated from the air, thereby preventing it from being trapped in the air. Oxygen oxidation.

Specifically, the gold film layer has a thickness of 30 to 300 nm.

Specifically, the atomic level two-dimensional material film includes graphene and transition metal sulfide. The transition metal sulfide includes tungsten disulfide, tungsten diselenide, molybdenum disulfide, molybdenum diselenide, tungsten dithide, molybdenum dichloride, antimony disulfide, antimony diselenide, zirconium diselenide, and At least one of zirconium sulfide, bismuth selenide, antimony disulfide, tin disulfide, and tin diselenide.

Specifically, the atomic level two-dimensional material slow saturable absorber heterojunction film comprises the atomic level two-dimensional material slow saturable absorber heterojunction film including molybdenum disulfide, molybdenum diselenide, zirconium diselide At least one of zirconium disulfide, tin disulfide, and tin diselenide. The atomic-level two-dimensional material fast saturable absorber heterojunction film includes graphene, tungsten disulfide, tungsten diselenide, tungsten disulfide, molybdenum disulfide, antimony disulfide, antimony diselenide, and selenium. At least one of bismuth oxide, bismuth disulfide, and indium selenide.

The constituent structures of the heterojunction saturable absorption mirror provided by the first embodiment of the present invention are simple in material, low in cost, and capable of wide-band modulation of light.

A second embodiment of the present invention provides a method for preparing an atomic level two-dimensional material heterojunction saturable absorption mirror, comprising the following steps:

S1: placing the substrate and the gold target in a vacuum chamber;

S2: ionizing the surface of the gold target to generate a plasma of gold, depositing the plasma of the gold on the substrate by magnetron sputtering deposition to form a gold film layer; by controlling deposition time and/or a deposition temperature to bring the gold film layer to a desired thickness;

S3: transferring an atomic-level two-dimensional material onto the gold film layer to form an atomic-level two-dimensional material film, and obtaining a heterojunction saturable absorption mirror.

A method for preparing a heterojunction saturable absorption mirror (satutable absorber) according to a second embodiment of the present invention, first placing a gold target and a substrate in a vacuum chamber, and using a magnetron sputtering deposition method to surface the gold target A plasma is formed after ionization, and the plasma is deposited on the substrate to form a gold film. In the deposition process, the thickness of the deposited gold film is controlled by controlling the deposition time and/or the deposition temperature; transferring a single layer (or multiple layers) of the two-dimensional material onto the gold-plated substrate to prepare an atom Hierarchical two-dimensional material heterojunction and fast and slow saturable absorber cascade" saturable absorption mirror.

Specifically, the transfer of the two-dimensional material onto the gold film layer is mainly carried out using an organic high molecular polymer such as polymethyl methacrylate (PMMA). The transfer process is as follows: 1) Preparation of two-dimensional materials (including fast absorbers and slow absorbers) of the desired atomic level using chemical vapor deposition on a sapphire/silicon substrate; 2) sapphire/silicon grown with material The surface of the substrate is covered with a suitable thickness of PMMA and placed in a drying oven to cure the PMMA into a film; 3) the substrate coated with the PMMA film is placed in a suitable concentration of NaOH solution to separate the PMMA film from the substrate (this) The atomic-scale two-dimensional material is transferred to the PMMA surface); 4) the PMMA film coated with the material is placed in an acetone solution to dissolve the PMMA; 5) the two-dimensional material of the atomic layer (including the fast absorber and the slow absorber) Transfer to the target substrate; 6) Isolation between the fast and slow absorbers using atomic-grade hexagonal boron nitride.

Specifically, the preparation method further includes

S4: The heterojunction saturable absorption mirror is encapsulated using hexagonal boron nitride to obtain a package protective layer.

Specifically, the saturable absorber is packaged using a single layer (or multiple layers of hexagonal boron nitride) according to a specific structure alternately transferred.

The second embodiment of the present invention prepares a "atomic layer two-dimensional material heterojunction and a fast and slow saturable absorber cascade" saturable absorption with adjustable band gap of the optical band of the saturable absorber by different two-dimensional material alternate structures. Mirror to achieve modulation of visible to mid-infrared light.

Referring to FIG. 2, a third embodiment of the present invention provides a pulsed fiber laser 200 including a sequentially connected semiconductor pump laser 1, an optical wavelength division multiplexer 2, a gain fiber 3, and an optical coupler 4. The optical isolator 5, the optical circulator 7 and the heterojunction saturable absorption mirror 8 described above, and the optical circulator 7 is connected to the optical wavelength division multiplexer 2 to form an annular cavity structure; wherein the optical isolator 5 is used After isolating the mode-locked laser, only the mode-locked laser is allowed to output in one direction in the pulsed fiber laser 200;

The pump light generated by the semiconductor pump laser 1 is coupled via the optical wavelength division multiplexer 2 into the gain fiber 3 to generate a laser pulse required for mode locking and amplify the laser pulse;

The optical coupler 4 outputs a part of the amplified laser pulse to the outside of the cavity and another part to the optical circulator 7, and the laser pulse entering the optical circulator 7 is coupled to the heterojunction saturable absorption mirror 8 for performing. After the mode-locking, the mode-locked laser pulse is returned to the optical wavelength division multiplexer 2 via the optical circulator 7, and then subjected to mode-locking amplification by the gain fiber 3, and then the pulsed laser is output through the optical coupler 4.

The pulsed fiber laser 200 provided by the third embodiment of the present invention includes the heterojunction saturable absorption mirror described above, and the "atomic level two-dimensional material heterojunction and fast and slow saturable absorber cascade" saturable absorption mirror The working principle is as a high reflection mirror of the pulsed fiber laser 200, when the laser in the pulsed fiber laser 200 is saturated by the "atomic level two-dimensional material heterojunction and fast and slow saturable absorber cascade" saturable absorption mirror When reflected, the laser can be modulated by a "atomic level two-dimensional material heterojunction and a fast and slow saturable absorber cascade" saturable absorption mirror. Specifically, the atomic-level two-dimensional material fast absorber heterojunction is mainly used to realize the self-starting and pulse compression of the fiber laser, and the atomic-level two-dimensional material slow absorber heterojunction is mainly used to suppress the noise in the cavity and improve the fiber laser cavity. Impulse stability within. The "atomic level two-dimensional material heterojunction and fast and slow saturable absorber cascade" saturable absorption mirror has high reliability, strong modulation capability, high environmental compatibility, wide application range, low cost, and broadband for light. Modulation and other advantages, as a mirror of light, can be used as a key device for pulsed laser generation in laser systems.

In the pulsed fiber laser 200 provided by the third embodiment of the present invention, the optical wavelength division multiplexer 2 couples the pump light generated by the semiconductor pump laser 1 into the gain fiber 3; the gain fiber 3 generates laser light required for mode locking and The mode-locking pulse is amplified; the heterojunction saturable absorption mirror 8 molds the laser, and the mode-locked laser is returned to the optical wavelength division multiplexer 2 via the optical circulator 7 and then passed through the gain fiber 3 After amplification, the pulsed laser light is output through the optical coupler 4.

Specifically, the optical circulator 7 couples the laser light generated by the gain fiber 3 into the heterojunction saturable absorption mirror 8 of the "atomic level two-dimensional material heterojunction and fast and slow saturable absorber cascade", heterogeneous The junction saturable absorption mirror 8 molds and reflects the laser light. After the reflection of the heterojunction saturable absorption mirror 8, the mode-locked laser light is returned through the original optical path and amplified by the gain fiber 3; the amplified laser light is output through the optical coupler 4.

Specifically, the pulsed fiber laser 200 further includes a polarization controller 6 connected between the optical isolator 5 and the optical circulator 7; the polarization controller 6 is used to control the polarization of the laser in the annular cavity status.

Referring to FIG. 3, a fourth embodiment of the present invention provides another pulsed fiber laser 300 comprising a sequentially connected semiconductor pump laser 11, an optical wavelength division multiplexer 12, a Bragg grating 13, and a gain fiber 14. And the heterojunction saturable absorption mirror 15 described above; the pump light generated by the semiconductor pump laser 11 is coupled to the Bragg grating 13 via the optical wavelength division multiplexer 12, and then enters the gain fiber 14 to generate laser light, which is heterogeneous. The junction saturable absorption mirror 15 molds the laser, and the mode-locked laser returns along the original path, and the pulsed laser is output via the optical wavelength division multiplexing laser 12.

Referring to FIG. 3, a fourth embodiment of the present invention provides another pulsed fiber laser 300 comprising a sequentially connected semiconductor pump laser 11, an optical wavelength division multiplexer 12, a Bragg grating 13, and a gain fiber 14. And the heterojunction saturable absorption mirror 15 described above;

The pump light generated by the semiconductor pump laser 300 is coupled to the Bragg grating 13 via the optical wavelength division multiplexer 12, transmitted through the Bragg grating 13, and then enters the gain fiber 14 to generate a laser pulse, and the heterojunction saturable absorption mirror 15 pairs The laser pulse is subjected to mode locking, and the mode-locked laser pulse is returned to the gain fiber 14 along the original path for amplification, and the amplified laser pulse is transmitted through the Bragg grating 13 and output by the optical wavelength division multiplexing laser 12.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A heterojunction saturable absorption mirror, characterized in that the heterojunction saturable absorption mirror comprises a substrate, a gold film layer covering the substrate, and an atomic level two-dimensional layer covering the gold film layer Material film

The atomic-level two-dimensional material film comprises an atomic-level two-dimensional material slow-saturated absorber heterojunction film, an isolating material and an atomic-level two-dimensional material fast saturable absorber heterojunction film.
The heterojunction saturable absorption mirror according to claim 1, wherein said atomic level two-dimensional material heterojunction saturable absorption mirror further comprises a package protection layer, said package protection layer covering said atomic level On the two-dimensional material film; the protective layer of the package is hexagonal boron nitride.
The heterojunction saturable absorption mirror according to claim 1, wherein the gold film layer has a thickness of 30 to 300 nm.
The heterojunction saturable absorption mirror according to claim 1, wherein the atomic level two-dimensional material slow saturable absorber heterojunction film comprises molybdenum disulfide, molybdenum diselenide, zirconium diselenide, At least one of zirconium disulfide, tin disulfide, and tin diselenide.
The heterojunction saturable absorption mirror according to claim 1, wherein the atomic level two-dimensional material fast saturable absorber heterojunction film comprises graphene, tungsten disulfide, tungsten diselenide, diterpene At least one of tungsten, germanium dihalide, antimony disulfide, antimony diselenide, antimony diselenide, antimony disulfide, and indium selenide.
A method for preparing a heterojunction saturable absorption mirror, comprising the steps of:

Placing the substrate and the gold target in a vacuum chamber;

The surface of the gold target is ionized to generate a plasma of gold, and the plasma of the gold is deposited on the substrate by magnetron sputtering deposition to form a gold film layer; by controlling deposition time and/or deposition temperature Bringing the gold film layer to a desired thickness;

An atomic-level two-dimensional material is transferred onto the gold film layer to form an atomic-level two-dimensional material film, and a heterojunction saturable absorption mirror is obtained.
The method for preparing a heterojunction saturable absorption mirror according to claim 6, wherein the preparation method further comprises:

The heterojunction saturable absorption mirror is encapsulated using hexagonal boron nitride to obtain a package protective layer.
A pulsed fiber laser, characterized in that the pulsed fiber laser comprises a sequentially connected semiconductor pump laser, an optical wavelength division multiplexer, a gain fiber, an optical coupler, an optical isolator, an optical circulator and claim 1 The heterojunction saturable absorption mirror according to any one of 5, wherein the optical circulator is connected to the optical wavelength division multiplexer to form an annular cavity structure; wherein the optical isolator is used for isolating the mode-locking The laser only allows the laser after mode locking to be output in one direction in the pulsed fiber laser;

The pump light generated by the semiconductor pump laser is coupled to the gain fiber through the optical wavelength division multiplexer to generate a laser pulse required for mode locking and amplify the laser pulse;

The optical coupler outputs a portion of the amplified laser pulse to the outside of the cavity and another portion to the optical circulator, and the laser pulse entering the optical circulator is coupled into the heterojunction. The saturation absorption mirror performs mode locking, and the mode-locked laser pulse is returned to the optical wavelength division multiplexer via the optical circulator, and then amplified by the gain fiber and then outputted by the optical coupler. laser.
A pulsed fiber laser according to claim 8 wherein said pulsed fiber laser further comprises a polarization controller located between said optical isolator and said optical circulator for controlling said annular cavity The polarization state of the laser.
A pulsed fiber laser, comprising: a sequentially connected semiconductor pump laser, an optical wavelength division multiplexer, a Bragg grating, a gain fiber, and the different one of claims 1 to 5. a saturable saturable absorption mirror;

The pump light generated by the semiconductor pump laser is coupled by an optical wavelength division multiplexer into a Bragg grating, which is transmitted through the Bragg grating and then enters the gain fiber to generate a laser pulse. The heterojunction saturable absorption mirror locks the laser pulse. The laser pulse after the mode-locking is returned to the gain fiber along the original path for amplification, and the amplified laser pulse is transmitted through the Bragg grating and then output by the optical wavelength division multiplexing laser.