CN114300923A - A kind of semiconductor saturable absorption mirror and preparation method thereof - Google Patents

Abstract

The invention provides a semiconductor saturable absorption mirror and a preparation method thereof, comprising: a substrate, a buffer layer, a distributed Bragg mirror layer, a lower isolation layer, a strain compensation multiple quantum well layer, an upper Isolation layer, lower dielectric film layer, upper dielectric film layer. The strain compensation multi-quantum well layer is formed by overlapping tensile strain quantum barrier layers and compressive strain quantum well layers, and the outer surfaces of the strain compensation multi-quantum well layers are all arranged as tensile strain quantum barrier layers. The total optical thickness of the lower isolation layer, the strain-compensated multiple quantum well layer, and the upper isolation layer is one of λ, 1.5λ, and 2λ, where λ is the lasing wavelength of the Yb-doped ultrafast fiber laser. The semiconductor saturable absorption mirror of the invention has a high modulation depth, and can realize automatic mode locking when applied to a Yb-doped fiber ultrafast laser, and the repetition period is stable.

Description

A kind of semiconductor saturable absorption mirror and preparation method thereof

technical field

The invention belongs to the technical field of ultrafast lasers, and in particular relates to a semiconductor saturable absorption mirror and a preparation method thereof.

Background technique

With its advantages of high peak power and narrow pulse width, ultrafast lasers have been widely used in the fields of fine material processing, biomedicine, scientific research, military and national defense. As a mode-locked device, semiconductor saturable absorber mirrors have been widely used in various types of ultrafast lasers such as solid-state, optical fibers, and semiconductors due to their advantages of self-starting, easy integration, wide coverage, compact structure, and flexible design. . At present, the mainstream picosecond solid-state and fiber lasers in the industrial market are passively mode-locked lasers based on semiconductor saturable absorber mirrors (SESAMs). The focus of the ultrafast laser industry.

The characteristic parameters of fiber lasers for SESAM are different from those of solid-state lasers. Solid-state lasers usually require a modulation depth of 0.5-3% for SESAM, while fiber lasers require a modulation depth of SESAM as high as 10-30%, which means that SESAM has a thicker SESAM. absorbing layer. The absorption layer of the SESAM applied to the Yb-doped fiber ultrafast laser is generally made of InGaAs material, in which the composition of In ranges from 25% to 32%, which causes a large mismatch between the InGaAs material and the GaAs substrate. Therefore, the critical value of InGaAs is The thickness is only about 10 nm, while the absorber layer thickness of SESAM with high modulation depth is hundreds of nanometers. Due to the large lattice mismatch, the quality of the epitaxial material of the absorber layer is easily deteriorated, resulting in the low damage threshold and short service life of the SESAM required for the Yb-doped fiber ultrafast laser.

At present, the SESAM required for domestic application of Yb-doped fiber lasers mainly relies on imports. However, imported products also have the problems of low damage threshold and short service life. Some domestic ultrafast laser manufacturers extend the use of SESAM by adding point changing devices. longevity and simplified maintenance work. These measures only increase the number of times the same SESAM is used, but do not fundamentally solve the problems of low damage threshold and short service life.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

In view of the existing technical problems, the present invention proposes a semiconductor saturable absorber mirror and a preparation method thereof; starting from SESAM itself, optimizing its epitaxial structure and improving material quality are used to at least partially solve one of the above technical problems.

(2) Technical solutions

One aspect of the present invention provides a semiconductor saturable absorber mirror, comprising: a substrate, a buffer layer, a distributed Bragg mirror layer, a lower isolation layer, a strain-compensated multiple quantum well layer, and an upper isolation layer stacked on the substrate in sequence The strain-compensated multi-quantum well layer is formed by overlapping tensile strain quantum barrier layers and compressive strain quantum well layers, and the outer surfaces of the strain-compensated multi-quantum well layers are all arranged as tensile strain quantum barrier layers.

Optionally, the substrate material includes GaAs material.

Optionally, the physical thickness of the upper isolation layer and the lower isolation layer is 4-10 nm.

Optionally, the total optical thickness of the lower isolation layer, the strain-compensated multiple quantum well layer, and the upper isolation layer is one of λ, 1.5λ, and 2λ, where λ is the lasing wavelength of the Yb-doped ultrafast fiber laser.

Optionally, the period number of the strain-compensated multiple quantum well layer is 10-45.

Optionally, the tensile strain quantum barrier layer material includes GaAsP material, and the compressive strain quantum well layer material includes InGaAs material.

Optionally, the physical thickness of the tensile strain quantum barrier layer and the compressive strain quantum well layer is 6-15 nm.

Optionally, the photoluminescence spectrum of the tensile strain quantum well layer is λ-λ+20 nm, where λ is the lasing wavelength of the Yb-doped ultrafast fiber laser.

Optionally, the semiconductor saturable absorption mirror further includes a lower dielectric film layer and an upper dielectric film layer stacked on the surface of the upper isolation layer 160 in sequence, and the optical thicknesses of the lower dielectric film layer and the upper dielectric film layer are both λ. /4, λ is the lasing wavelength of the Yb-doped ultrafast fiber laser.

Another aspect of the present invention provides a preparation method applied to a semiconductor saturable absorber mirror, comprising: sequentially stacking a buffer layer, a distributed Bragg mirror layer, a lower isolation layer, a strain-compensated multiple quantum well layer, an upper The isolation layer, the lower dielectric film layer, and the upper dielectric film layer; wherein, the strain compensation multi-quantum well layer is formed by overlapping a tensile strain quantum barrier layer and a compressive strain quantum well layer, and the outer surface of the strain compensation multi-quantum well layer is arranged as The tensile strain quantum barrier layer.

(3) Beneficial effects

(1) The strain compensation multi-quantum well layer is adopted in the structure of the present application, which can effectively alleviate the deterioration of material quality caused by heterocrystalline lattice mismatch, and effectively improve its damage threshold and service life.

(2) The total optical thickness of the lower isolation layer, the upper isolation layer and the strain-compensated multiple quantum well layer is one of λ, 1.5λ, and 2λ; it reduces the absorption of incident light by other materials, effectively reduces unsaturated loss, and is easy to implement Mode-locking reduces the thermal effect of the SESAM, resulting in a longer service life.

(3) The lower dielectric film layer and the upper dielectric film layer are sequentially prepared on the surface of the upper isolation layer, which not only protects the SESAM wafer, but also helps to improve the damage threshold of the SESAM.

Description of drawings

Fig. 1 is the structural representation of SESAM in the embodiment of the present invention;

Fig. 2 is the photoluminescence spectrum test chart of the SESAM epitaxial wafer in the embodiment of the present invention;

3 is a flowchart of a method for fabricating a semiconductor saturable absorption mirror provided by an embodiment of the present invention;

Fig. 4 is the high-resolution X-ray twin-crystal diffraction rocking curve test chart of the SESAM epitaxial wafer in the embodiment of the present invention;

Fig. 5 is the reflectivity test chart of SESAM in the embodiment of the present invention;

6 is an output spectrogram of a SESAM mode-locked Yb-doped fiber laser in an embodiment of the present invention;

7 is a mode-locked pulse sequence output on an oscilloscope by a SESAM mode-locked Yb-doped fiber laser in an embodiment of the present invention;

FIG. 8 is an autocorrelator test diagram of the output pulse of the SESAM mode-locked Yb-doped fiber laser in the embodiment of the present invention.

110-substrate, 120-buffer layer, 130-distributed Bragg mirror layer, 140-lower isolation layer, 150-strain compensation multiple quantum well layer, 160-upper isolation layer, 170-lower dielectric film layer, 180-upper Dielectric film layer, 131-GaAs layer in the distributed Bragg mirror layer structure, 132-AlGaAs layer in the distributed Bragg mirror layer structure, 151- tensile strain quantum barrier layer, compressive strain quantum well layer-152.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present disclosure will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present disclosure.

Terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure; the terms "upper," "lower," "front," "rear," "left," "right," etc. indicate orientation or position The words of the relationship are based on the orientation or positional relationship shown in the attached drawings, or the orientation or positional relationship that the product of the application is usually placed in use, and are only for the convenience of describing the application and simplifying the description, rather than indicating or implying that The device or element must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the application; the terms "comprising", "comprising", etc. used herein indicate the features, steps, operations and/or One or more other features, steps, operations, or components are present, but not precluded, or added.

In view of the deficiencies of the prior art, the present disclosure provides a semiconductor saturable absorber mirror and a preparation method thereof. Starting from SESAM itself, by optimizing its epitaxial structure and improving the quality of materials, the problems of low damage threshold and short service life of SESAM can be solved from the root cause. question.

FIG. 1 schematically shows a semiconductor saturable absorber mirror provided by an embodiment of the present disclosure. It should be noted that FIG. 1 is only an example to which the embodiment of the present disclosure can be applied, so as to help those skilled in the art to understand the present disclosure It does not mean that the embodiments of the present disclosure cannot be used in other occasions.

As shown in FIG. 1 , the semiconductor saturable absorber mirror of the present invention includes: a substrate 110 , a buffer layer 120 , a distributed Bragg reflector (DBR) layer 130 , a lower space layer 140 , and a strain-compensated multiple quantum well layer 150 , an upper spacer layer 160 , a lower dielectric film layer 170 , and an upper dielectric film layer 180 .

In the embodiment of the present invention, the material of the substrate 110 includes GaAs material, and further may include N-type Si-doped GaAs material, the physical thickness may be, for example, 450 μm, and the epitaxial growth surface is an off-angle of 2° toward the (110) direction. (100) faces. The buffer layer 120 is disposed on the surface of the substrate 110 , the material includes GaAs material, and the physical thickness may be 0.5-2 μm. The DBR layer 130 is disposed on the surface of the buffer layer 120, and includes a GaAs layer 131 and an AlGaAs layer 132 sequentially stacked on the buffer layer 120. The material of the GaAs layer 131 may include GaAs material, and the material of the AlGaAs layer 132 may include AlGaAs material, forming a DBR layer. For example, the period of the AlGaAs layer 132 can be 30, the composition in the AlGaAs layer 132 can be, for example, the Al composition is 0.9, the Ga composition is 0.1, the As composition is 1, and the optical thicknesses of the AlGaAs layer 132 and the GaAs layer 131 are both λ/4, Wherein, λ is the lasing wavelength of the Yb-doped ultrafast fiber laser, and λ can be, for example, 1064 nm.

For AlGaAs materials with high Al composition, the physical thickness of the buffer layer is very important to improve the quality of the AlGaAs material. When the physical thickness of the buffer layer is greater than or equal to 0.5 μm, high-quality AlGaAs materials can be obtained, and with the increase of the Al composition value , the physical thickness of the buffer layer is required to be thicker; for example, the composition of the AlGaAs layer 132 can be that the Al composition is 0.9, the Ga composition is 0.1, and the As composition is 1, which can effectively reduce the incorporation of "oxygen", thereby improving the DBR130 material quality, reducing the unsaturated absorption loss of SESAM.

In the embodiment of the present invention, a lower space layer 140 , a strain-compensated multiple quantum well layer 150 , and an upper space layer 160 are sequentially stacked on the surface of the AlGaAs layer 132 , and the strain-compensated multiple quantum well layer 150 includes tensile strains stacked on the surface of the lower space 140 in sequence. The quantum barrier layer 151 and the compressively strained quantum well layer 152 . The sequence of stacking the strain-compensated multiple quantum well layers 150 on the surface of the lower space layer 140 is quantum barrier layer 151, quantum well layer 152, quantum barrier layer 151... Quantum barrier layer 151, quantum well layer 152, quantum barrier layer 151, the number of cycles For example, it can be 10-45. During the stacking process of the strain-compensated multiple quantum well layers 150 , the quantum barrier layer 151 is first stacked on the surface of the lower space layer 140 , and the last stack is also the quantum barrier layer 151 at the end. Therefore, the stacking period of the quantum barrier layer 151 is The number is one more than the number of stacking periods of the quantum well layers 152 . The material of the quantum barrier layer 151 includes GaAsP material, wherein the As composition is 0.7-0.95, the P composition is 0.05-0.3, the material of the quantum well layer 152 includes InGaAs material, the In composition is 0.25-0.32, and the Ga composition is 0.68- 0.75. The material of the lower space layer 140 and the upper space layer 160 includes GaAs material; the physical thickness of the quantum barrier layer 151 and the quantum well layer 152 is 6-15 nm, and the physical thickness of the lower space layer 140 and the upper space layer 160 is 4-10 nm.

In the strained layer, due to the existence of strain energy in each monolayer, each monolayer has a critical thickness, and when the thickness of the strained layer exceeds this critical thickness, the strained layer will relax, resulting in the strained layer The quality of the material deteriorates, which in turn affects the performance of the device. Based on the theory of strain compensation structure, the present application arranges the strain compensation multi-quantum well layer 150 in a cross-stacked shape of a tensile strain quantum barrier layer 151 and a compressive strain quantum well layer 152. The material of the tensile strain quantum barrier layer 151 includes GaAsP material, and the compressive strain The material of the quantum well layer 152 includes InGaAs material, wherein the strain of the GaAsP material in the tensile strain quantum barrier layer 151 relative to the GaAs substrate and the strain of the InGaAs material in the compressive strain quantum well layer 152 relative to the GaAs substrate are two opposite types. strain, which can offset the net strain value of the overall structure. Therefore, the net strain of the multi-quantum well layer 150 of the present application in each cycle is relatively small, and the stability of the entire strained quantum well structure is maintained without strain relaxation, thereby ensuring the material quality.

For the convenience of description, the physical thicknesses of the lower space layer 140, the quantum barrier layer 151, the quantum well layer 152, and the upper space layer 160 are respectively expressed as h ₁ , h ₂ , h ₃ , and h ₄ , and the lower space layer 140 , The optical thicknesses of the quantum barrier layer 151, the quantum well layer 152, and the upper space layer 160 are _denoted as _h1 ', h2', _h3 ', _h4 ', and the lower space layer 140, the quantum barrier layer 151, and the quantum well layer 152 and the refractive indices of the material of the upper space layer 160 are represented as n ₁ , n ₂ , n ₃ , and n ₄ respectively, and the number of stacking periods of the strain-compensated multiple quantum well layer 150 is represented as n. h ₁ , h ₂ , h ₃ , h ₄ and n must be selected so that the total optical thickness of the sum of h ₁ ', (n+1)h ₂ ', nh ₃ ', h ₄ ' is λ, 1.5λ, 2λ One of them, the total optical thickness is one of λ, 1.5λ, and 2λ, which ensures that the SESAM of the present invention is a resonant type. The saturation flux of the Yb-doped fiber laser meets the requirements of the mode-locked device of the Yb-doped fiber laser. The resonant SESAM can obtain a relatively large modulation depth through the multiple quantum well structure with a relatively small period. The specific selection of the total optical thickness is determined according to the requirement of the modulation depth, wherein the conversion formula between the optical thickness and the physical thickness is: h _i '=h _i *n _i .

2 is a photoluminescence spectrum test diagram of the SESAM epitaxial wafer in the embodiment of the present invention, the photoluminescence spectrum (PL) of the compressive strain quantum well layer 152 in the strain compensation multiple quantum well layer 150 is λ-λ+20 nm, and the pressure The photoluminescence spectrum of the strained quantum well layer 152 is slightly longer than the lasing wavelength of the fiber laser, which is favorable for the saturable absorption of the SESAM.

In the embodiment of the present invention, a lower dielectric film layer 170 and an upper dielectric film layer 180 are sequentially stacked on the surface of the upper space layer 160 , the material of the lower dielectric film layer 170 includes Si ₃ N ₄ material, and the material of the upper dielectric film layer 180 includes SiO ₂ Material, the optical thickness of the lower dielectric film layer 170 and the upper dielectric film layer 180 can be both λ/4, and the physical thickness can be 132.3nm and 180.9nm respectively. The dielectric film can play a good role in protecting the SESAM wafer. Helps increase the damage threshold of SESAM.

Based on the above-mentioned semiconductor saturable absorber mirror, an embodiment of the present invention further provides a method for fabricating a semiconductor saturable absorber mirror.

FIG. 3 schematically shows a flow chart of a method for fabricating a semiconductor saturable absorption mirror provided by an embodiment of the present invention.

As shown in FIG. 3, the method may include steps S201-S207, for example.

S201 , depositing and preparing a buffer layer 120 on the surface of the substrate 110 .

Specifically, the material of the substrate 110 includes an N-type GaAs material. Before preparing the buffer layer 120, the substrate 110 needs to be deoxidized. For example, the deoxidation process may include: placing the substrate 110 into metal organic compound chemical vapor deposition (MOCVD) In the reaction chamber, through computer automation program control, change the nitrogen gas into the MOCVD reaction chamber to hydrogen, reduce the pressure of the reaction chamber to, for example, 50mbar, and then increase the temperature. ₃ valve, and pass it into the reaction chamber, raise the temperature of the reaction chamber to, for example, 750 °C under the protection of AsH atmosphere, and stabilize for ₁₀ minutes; high temperature deoxidation treatment of the substrate 110 is necessary before material deposition, because by During high temperature heat treatment, the oxide layer on the surface of the substrate 110 is removed, and the quality of the material deposited thereon will be significantly improved. At the same time, since the substrate 110 will be decomposed at high temperature, it needs to be protected by passing AsH ₃ .

After the deoxidation treatment of the substrate 110 is completed, the temperature of the reaction chamber is lowered to, for example, 690° C. under the protection of AsH ₃ . After it is stabilized, the TMGa source is turned on to deposit the buffer layer 120 . The buffer layer material includes GaAs material.

S202 , depositing and preparing a distributed Bragg mirror layer (DBR) on the surface of the buffer layer 120 .

Specifically, after the deposition of the buffer layer 120 is completed, the TMGa source is turned off, and the temperature of the reaction chamber is maintained at 690° C. for 30 cycles of deposition of the DBR layer 130 , wherein the DBR layer material includes AlGaAs/GaAs material.

S203 , depositing and preparing a lower space layer 140 on the surface of the DBR layer 130 .

Specifically, after the deposition of the DBR layer 130 is completed, the temperature of the reaction chamber is kept at 690° C. to deposit the lower space layer, and the material of the lower space layer 140 includes GaAs material.

S204 , depositing and preparing the strain-compensated multiple quantum well layer 150 on the surface of the lower space layer 140 .

Specifically, after the deposition of the lower space layer 140 is completed, the temperature of the reaction chamber is lowered to, for example, 580° C. After it is stabilized, periodic deposition of the strain-compensated multi-quantum well layer 150 is performed, and the strain-compensated multi-quantum well layer 150 passes through the tensile strain quantum barrier layer. 151 and the compressive strain quantum well layer 152 are cross-stacked, and the outer surface of the strain compensation multiple quantum well layer 150 is arranged as a tensile strain quantum barrier layer 151 and a tensile strain quantum barrier layer. The material of 151 includes GaAsP material, and the material of compressive strain quantum well layer 152 includes InGaAs material. Lowering the temperature of the reaction chamber to, for example, 580 °C, is to obtain high-quality strained quantum well materials and suppress the transition of the InGaAs/GaAsP multiple quantum well growth mode from two-dimensional (2D) to three-dimensional (3D), mainly due to the high The lattice mismatch between the InGaAs epitaxial layer of In composition and the GaAs substrate is large, and the induced stress can lead to lattice relaxation. During the rapid migration of III and V atoms, In atoms can easily reach the growth surface defects to form some low-energy nucleation sites, resulting in the formation of In-rich islands, and the epitaxial layer is transformed from 2D growth to 3D growth. Thereby forming a large number of defects affecting the quality of the material.

S205 , a space layer 160 is stacked and deposited on the surface of the strain-compensated multiple quantum well layer 150 .

Specifically, after the deposition of the strain-compensated multi-quantum well layer 150 is completed, the temperature of the reaction chamber is kept at 580°C, and the deposition of the upper space layer 160 is performed. The material of the upper space layer 160 includes GaAs material. The total optical thickness of the multiple quantum well layer 150 and the upper space 160 is one of λ, 1.5λ, and 2λ.

S206 , depositing and preparing the lower dielectric film layer 170 on the surface of the upper space layer 160 .

After the deposition of the upper space layer 160 is completed, the temperature of the reaction chamber is lowered to, for example, 500° C. After it is stabilized, the hydrogen gas introduced into the reaction chamber is switched to nitrogen, and annealed in a nitrogen environment for, for example, 10 minutes to obtain wafer 1; the deposition is completed The annealed wafer is placed in a reaction chamber of a plasma-enhanced chemical vapor deposition (PECVD) apparatus to prepare the lower dielectric film layer 170 . The lower dielectric film layer 170 can be, for example, a Si ₃ N ₄ dielectric film layer, and the preparation conditions can be, for example, when the temperature of the reaction chamber is raised to, for example, 280° C., SiH ₄ and NH ₃ are passed into the reaction chamber, and the SiH ₄ and NH 3 are adjusted to the reaction chamber. The flow rate of NH ₃ gas is such that the growth rate of the Si ₃ N ₄ dielectric film is 1.0 nm/s.

S207 , depositing and preparing the upper dielectric film layer 180 on the surface of the lower dielectric film layer 170 .

Specifically, after the preparation of the lower dielectric film layer 170 is completed, the preparation of the upper dielectric film layer 180 is continued in the reaction chamber of the PECVD equipment. The upper dielectric film layer 180 can be, for example, a SiO ₂ dielectric film layer, and the preparation conditions can be, for example, maintaining the temperature of the reaction chamber at 280° C., passing SiH ₄ and N ₂ O into the reaction chamber, and adjusting the SiH ₄ and N ₂ O gases flow so that the growth rate of the SiO ₂ dielectric film is 1.0 nm/s.

Before the preparation of the lower dielectric film layer 170 and the upper dielectric film layer 180 is performed, corresponding tests are performed on the characteristic parameters of the epitaxial wafer through relevant test methods to ensure that they are consistent with the designed structure.

It should be noted that: in order to meet the requirement of the fiber laser that the modulation depth of the SESAM reaches 10-30%, the technical solution proposed in this application, by setting the total optical thickness of the lower space layer 140, the multiple quantum well layer 150, and the upper space layer 160 to One of λ, 1.5λ, and 2λ can meet the requirements, and it is ensured that the total optical thickness of the lower space layer 140, the multiple quantum well layer 150, and the upper space layer 160 is set to one of λ, 1.5λ, and 2λ. The physical thickness of the lower space layer 140, the multiple quantum well layer 150, the upper space layer 160, and the number of periods of the multiple quantum well layer 150 are freely selected within the parameter range of the parameter, and the lower space layer 140, the multiple quantum well layer 150, the upper space layer 150 and the upper space layer 150 are not specified. The physical thickness of the space layer 160 and the period number of the multiple quantum well layer 150 .

In order to illustrate the technical solutions of the present application more clearly, the following descriptions are given by way of illustrative specific embodiments.

Embodiment 1: The substrate 110 is made of N-type Si-doped GaAs material, the physical thickness is 450 μm, and the epitaxial growth surface is the (100) plane with an off-angle of 2° toward the (110) direction; the buffer layer is arranged on the surface of the substrate 110, GaAs material is selected, the physical thickness is 1 μm; the distributed Bragg reflector (DBR) layer 130 is arranged on the surface of the buffer layer 120, including the GaAs layer 131 and the AlGaAs layer 132 stacked on the buffer layer 120 in sequence, and the period of forming the DBR layer is 30. The composition of the AlGaAs layer 132 is that the Al composition is 0.9, the Ga composition is 0.1, and the As composition is 1. The optical thicknesses of the AlGaAs layer 132 and the GaAs layer 131 are both λ/4, and λ is the Yb-doped ultrafast fiber laser. The lasing wavelength is 1064 nm, and the surface of the AlGaAs layer 132 is sequentially stacked with a lower space layer 140, a strain-compensated multiple quantum well layer 150, an upper space layer 160, a lower dielectric film layer 170, and an upper dielectric film layer 180. The material of the lower space layer 140 and the upper space layer 160 is GaAs, the physical thickness is 4 nm, and the refractive index of GaAs is 3.454; the period number of the strain compensation multi-quantum well layer 150 is 30, including the quantum barrier layers sequentially stacked on the surface of the lower space 140 layer 151 and quantum well layer 152; wherein, the material of the quantum barrier layer 151 is GaAsP material, the refractive index is 3.521, the physical thickness is 9.7nm, the number of periods is 31, the material of the quantum well layer 152 is InGaAs material, the refractive index is 3.472, and the thickness is 10nm, the number of cycles is 30, the material of the lower dielectric film layer 170 is Si ₃ N ₄ material, and the material of the upper dielectric film layer 180 is SiO ₂ material; the physical thicknesses of the lower dielectric film layer 170 and the upper dielectric film layer 180 are 132.3 nm and 180.9nm. The optical thickness of the lower space 140 is: 4×3.454=13.816nm, the total optical thickness of the quantum barrier layer 151 is: 31×9.7×3.521=1058.7647nm, and the total optical thickness of the quantum well layer 152 is: 30×10×3.472=1041.6 nm, the optical thickness of the upper space layer 160 is: 4×3.454=13.816 nm; the total optical thickness of the lower space 140, the strain-compensated multiple quantum well layer 150, and the upper space 160 is: 13.816+1058.7647+1041.6+13.816=2127.9967nm≈2λ= 2128 nm; the total optical thickness of the lower space 140, the strain-compensated multi-quantum well layer 150, and the upper space 160 is 2λ, which meets the requirements of the fiber laser for SESAM modulation depth.

Example 2, Example 2 differs from Example 1 in that the number of periods of the strain compensation multi-quantum well layer 150 is 45, the physical thickness of the quantum barrier layer 151 is 7.18 nm, the number of periods is 46, and the physical thickness of the quantum well layer 152 is 6nm, the number of periods is 45, the total optical thickness of the quantum barrier layer 151 is: 46×7.18×3.521=1162.9159nm, the total optical thickness of the quantum well layer 152 is: 45×6×3.472=937.44nm, other parameters and example 1 same. The total optical thickness of the lower space140, the strain-compensated multiple quantum well layer 150, and the upper space160 is: 13.816+1162.9159+937.44+13.816=2127.9879nm≈2λ=2128nm, the total optical thickness of the lower space140, the strain-compensated multiple quantum well layer 150, and the upper space160 The thickness is 2λ, which meets the requirement of fiber laser for SESAM modulation depth.

Other implementation details are similar to those in Embodiment 1, and are not repeated here.

Example 3, Example 3 differs from Example 1 in that the number of periods of the strain compensation multi-quantum well layer 150 is 20, the physical thickness of the quantum barrier layer 151 is 8.381 nm, the number of periods is 21, and the physical thickness of the quantum well layer 152 is 6nm, the number of periods is 20, the total optical thickness of the quantum barrier layer 151 is: 21×8.381×3.521=619.7nm, the total optical thickness of the quantum well layer 152 is: 20×6×3.472=416.64nm, other parameters and example 1 same. The total optical thickness of the lower space140, the strain-compensated multiple quantum well layer 150, and the upper space160 is: 13.816+619.7+416.64+13.816=1063.972nm≈λ=1064nm, the total optical thickness of the lower space140, the strain-compensated multiple quantum well layer 150, and the upper space160 The thickness is λ, which meets the requirement of the fiber laser for SESAM modulation depth.

Other implementation details are similar to those in Embodiment 1, and are not repeated here.

Example 4, Example 4 differs from Example 1 in that the number of periods of the strain compensation multi-quantum well layer 150 is 30, the physical thickness of the quantum barrier layer 151 is 6.735 nm, the number of periods is 31, and the physical thickness of the quantum well layer 152 is 6nm, the number of periods is 30, the total optical thickness of the quantum barrier layer 151 is: 31×6.735×3.521=735.132nm, the total optical thickness of the quantum well layer 152 is: 30×8×3.472=833.28nm, other parameters and example 1 same. The total optical thickness of the lower space140, the strain-compensated multiple quantum well layer 150, and the upper space160 is: 13.816+735.132+833.28+13.816=1596.044nm≈1.5λ=1596nm, the total optical thickness of the lower space140, the strain-compensated multiple quantum well layer 150, and the upper space160 The optical thickness is 1.5λ, which meets the requirement of the fiber laser for SESAM modulation depth.

Other implementation details are similar to those in Embodiment 1, and are not repeated here.

Fig. 4 is the high-resolution X-ray double crystal diffraction rocking curve of the SESAM epitaxial wafer in the embodiment of the present invention. Since the AlGaAs/GaAs DBR and the strain-compensated InGaAs/GaAsP multiple quantum wells are all multi-periodic structures, as shown in Fig. 4, Periodic diffraction peaks will appear in the rocking curve, and the periodic thickness of the epitaxial material can be calculated from the spacing between adjacent diffraction peaks.

Fig. 5 is the reflectivity test chart of SESAM in the embodiment of the present invention, the reflectivity is the comprehensive characterization of AlGaAs/GaAs DBR and InGaAs/GaAsP multiple quantum wells, and the epitaxial growth of AlGaAs/GaAs DBR and InGaAs/GaAsP can be measured according to the reflectivity The parameters are adjusted accordingly to obtain epitaxial materials that meet the requirements.

6 is an output spectrum diagram of the SESAM in an embodiment of the present invention applied to a linear cavity Yb-doped fiber ultrafast laser, and the center wavelength of the output pulse is 1064.5 nm.

FIG. 7 is a mode-locked pulse sequence output on an oscilloscope by applying the SESAM in an embodiment of the present invention to a linear cavity Yb-doped fiber ultrafast laser output on an oscilloscope.

8 is an autocorrelator test result of applying the SESAM in the embodiment of the present invention to the output pulse of the linear cavity Yb-doped fiber ultrafast laser, and the pulse width of the output pulse is 9.6 ps.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in further detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. a semiconductor saturable absorption mirror, is characterized in that, comprises: a substrate (110); A buffer layer (120), a distributed Bragg mirror layer (130), a lower isolation layer (140), a strain-compensated multiple quantum well layer (150), and an upper isolation layer ( 160); The strain compensation multiple quantum well layer (150) is formed by overlapping a tensile strain quantum barrier layer (151) and a compressive strain quantum well layer (152), and the outer surfaces of the strain compensation multiple quantum well layer (150) are all arranged is the tensile strain quantum barrier layer (151). 2. The semiconductor saturable absorber mirror according to claim 1, wherein the substrate (110) material comprises GaAs material. 3. The semiconductor saturable absorption mirror according to claim 1, wherein the physical thickness of the lower isolation layer (140) and the upper isolation layer (160) is 4-10 nm. 4. The semiconductor saturable absorber mirror according to claim 1, wherein the total optical thickness of the lower isolation layer (140), the strain-compensated multiple quantum well layer (150), and the upper isolation layer (160) is one of λ, 1.5λ, and 2λ, where λ is the lasing wavelength of the Yb-doped ultrafast fiber laser. 5 . The semiconductor saturable absorption mirror according to claim 1 , wherein the period of the strain-compensated multiple quantum well layer ( 150 ) is 10-45. 6 . 6. The semiconductor saturable absorber mirror according to claim 1, wherein the material of the tensile strain quantum barrier layer (151) comprises GaAsP material, and the material of the compressive strain quantum well layer (152) comprises InGaAs material. 7 . The semiconductor saturable absorption mirror according to claim 1 , wherein the physical thickness of the tensile strain quantum barrier layer ( 151 ) and the compressive strain quantum well layer ( 152 ) is 6-15 nm. 8 . 8. The semiconductor saturable absorption mirror according to claim 1, wherein the photoluminescence spectrum of the compressive strain quantum well layer (152) is λ-λ+20 nm, wherein λ is a Yb-doped ultrafast fiber The lasing wavelength of the laser. 9 . The semiconductor saturable absorption mirror according to claim 1 , further comprising: a lower dielectric film layer ( 170 ) and an upper dielectric film layer ( 180 ) sequentially stacked on the surface of the upper isolation layer ( 160 ). 10 . ), the optical thicknesses of the lower dielectric film layer (170) and the upper dielectric film layer (180) are both λ/4, where λ is the lasing wavelength of the Yb-doped ultrafast fiber laser. 10. A method for preparing a semiconductor saturable absorber mirror applied in any one of claims 1-9, comprising: stacking a buffer layer (120) and a distributed Bragg mirror layer in sequence on the surface of a substrate (110) (130), a lower isolation layer (140), a strain compensation multiple quantum well layer (150), an upper isolation layer (160), a lower dielectric film layer (170), and an upper dielectric film layer (180), wherein the strain compensation The multiple quantum well layer (150) is formed by overlapping a tensile strain quantum barrier layer (151) and a compressive strain quantum well layer (152), and the outer surfaces of the strain compensation multiple quantum well layer (150) are all arranged such that the tension Strained quantum barrier layer (151).

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