An Erbium-Doped Bismuth Silicate Laser Crystal and Its Preparation Method
By employing the crucible lowering method and the rare-earth ion Er³⁺-doped bismuth silicate crystal growth process, the problems of component volatilization and segregation were solved, and high-quality Er:BSO crystals were prepared, which are suitable for fields such as optical fiber communication and lidar.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI INST OF TECH
- Filing Date
- 2026-05-15
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies struggle to grow high-quality Er³⁺-doped bismuth silicate (BSO) crystals, especially in the crucible-lowering method where component volatilization and segregation lead to crystal defects, limiting its application in 1.54µm laser output.
A crucible-lowering method combined with rare earth ion Er³⁺ doping was used to grow bismuth silicate crystals through solid-state sintering and crucible-lowering. The volatilization of components was controlled, ensuring crystal integrity and laser performance. The growth direction and size were controllable, making it suitable for mass production.
Er:BSO crystals with high transmittance and low laser loss are grown, exhibiting excellent laser output performance. They are suitable for fields such as fiber optic communication and lidar, and have low production costs, making them suitable for large-scale enterprise production.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of crystal growth technology, and specifically discloses an erbium-doped bismuth silicate laser crystal in the mid-infrared band and its preparation method. Background Technology
[0002] Lasers are one of the most significant inventions of the 20th century. Compared to traditional light sources, lasers, with their superior coherence, monochromaticity, and brightness, have long been called "the fastest knife," "the most accurate ruler," and "the key to industrial manufacturing." In 1916, A. Einsteini proposed the concept of stimulated emission, thus giving birth to the laser. For a century, lasers have been a hot research topic for scientists worldwide, driving progress and transformation in industries such as industry, medicine, military, and aerospace, and effectively promoting the development and improvement of human life and production methods.
[0003] Lasers with a wavelength of 1.5μm have a much higher incident energy in the human eye than lasers of other wavelengths, and are therefore known as eye-safe lasers. Furthermore, this wavelength falls within a favorable atmospheric transmission window, allowing it to effectively penetrate smoke and other harsh environments, making it ideal for outdoor use. In addition, silica optical fibers in this wavelength range have the lowest loss, making it the optimal operating wavelength for fiber optic communication systems. Therefore, they are widely used in fields such as lidar, laser ranging, remote sensing, and optical communication.
[0004] Bismuth silicate (Bi4Si3O) 12 Bi₂O₃ (BSO) crystal is a near-uniform melting compound in the Bi₂O₃-SiO₂ pseudobinary system. It belongs to the same cubic crystal system as Bi₂O₃ (BGO) crystal, has a similar melting point, and a thermal conductivity of 3.29 W·m⁻¹ at 298 K. -1 Ho3, with a Mohs hardness of 5, is easy to process, has low phonon energy, and good thermal conductivity, making it a high-quality laser matrix crystal. Previous studies have shown that Ho3 can be grown using the crucible lowering method. 3+ Yb 3+ Tm 3+ Plasma-doped BSO crystals exhibit good spectral characteristics and have achieved laser output. However, regarding Er... 3+ No reports have been found regarding doped BSO crystals.
[0005] According to international standards, lasers with wavelengths exceeding 1.4µm are considered "eye-safe" lasers. Among them, the 1.54µm laser excited by Er³⁺ possesses unique safety characteristics. After entering the eye, over 98% of its energy is absorbed by the cornea and lens at the front of the eye, with almost no energy reaching the highly sensitive retina, thus fundamentally eliminating the risk of permanent eye damage. More importantly, the 1.54µm emission wavelength of Er³⁺ falls precisely within the lowest loss window (C-band) of fiber optic communication and matches the atmospheric transmission window. This makes this band irreplaceable in applications such as fiber optic communication, lidar, and long-range ranging.
[0006] Er³⁺ is a well-known active ion in near-infrared and upconversion emission luminescence of solid-state lasers, with the electronic configuration [Xe]⁴f. 12 Er³⁺ has a complex and multi-level energy structure, enabling laser output from the visible to the infrared region. Its main emission levels are, respectively, corresponding to… 4 S 3 / 2 → 4 I 15 / 2 A laser at around 520 nm, corresponding to 4 I 13 / 2 → 4 I 15 / 2 The 1.5 μm near-infrared laser output and corresponding 4 I 11 / 2 → 4 I 13 / 2 The ~3μm mid-infrared laser output transitions.
[0007] BSO crystal growth methods include the Czochralski method and the crucible lowering method. In the Bi₂O₃-SiO₂ pseudobinary phase diagram, the significant differences in density and melting point between Bi₂O₃ and SiO₂ lead to complex phase relationships, making component segregation highly likely during crystal growth, resulting in crystal defects and even growth failure. While the Czochralski method can grow BSO crystals, the volatilization and corrosion of Bi limit the size and quality of the resulting crystals. Compared to the Czochralski method, the crucible lowering method offers several advantages: it is suitable for growing large-sized crystals; the appearance and size of the crucible directly determine the appearance and size of the crystal; the completely enclosed crystal growth environment prevents Bi₂O₃ volatilization, effectively reducing component segregation; the crucible lowering method has a smaller temperature gradient and allows for a very slow growth rate, ensuring a stable crystal growth interface; temperature control is simple, generally preventing excessive furnace temperature leading to crucible corrosion; and multiple crystals can be grown in the same furnace, making it suitable for mass production. Summary of the Invention
[0008] The purpose of this invention is to provide a bismuth silicate laser crystal and its preparation method, which achieves laser output performance at 1.54µm by erbium ion doping.
[0009] To achieve the above objectives, the technical solution of the present invention is as follows:
[0010] An erbium-doped bismuth silicate laser crystal is disclosed, wherein the bismuth silicate crystal is doped with Er³⁺, wherein the Er³⁺ is doped in the form of Er₂O₃, and the doping amount is 0.5~2 at.%. The molecular formula of the bismuth silicate crystal is Bi₄Si₃O₃. 12 .
[0011] Furthermore, the Er₂O₃ doping concentration is 0.5~2 at.%.
[0012] Furthermore, the present invention also relates to a method for preparing an erbium-doped bismuth silicate laser crystal, comprising the following steps:
[0013] (1) Select high-purity SiO2 and Bi2O3 raw materials, prepare them according to the stoichiometric ratio, and use solid-state sintering method to sinter at 750~850℃ for 6~15 hours to obtain Bi4Si3O 12 Polycrystalline material; doped with Bi4Si3O at a doping concentration of 0.5~2 at.%. 12 Er₂O₃ was added to the polycrystalline material, ground and mixed evenly, and then sintered at around 850℃ for 5-10 hours to obtain erbium-doped Bi₄Si₃O₃. 12 Polycrystalline material;
[0014] (2) Select a bismuth silicate seed crystal, fix the seed crystal in the seed well part at the bottom of the crucible, and load the synthesized doped polycrystalline material into the crucible fixed with Bi4Si3O. 12 Place the seed crystal in the crucible and seal it, then move it into the ceramic dropper tube at an appropriate height.
[0015] (3) Heat the crystal furnace to 1050-1200℃ in 12-20h and keep it at that temperature for 4-12 hours; gradually raise the ceramic tube, and after the polycrystalline material melts in a certain area above the seed crystal to form a stable melting zone, inoculate it and keep it at that temperature for 1-3h.
[0016] (4) The ceramic tube is moved down at a speed of 0.2~0.6 mm / h to grow the crystal. After cooling to room temperature, the crucible is peeled off to obtain the erbium-doped bismuth silicate laser crystal.
[0017] Furthermore, the optimal orientation of the BSO seed crystal in step (2) is as follows: <001> Other orientations include <010> , <100> And other required directions.
[0018] Furthermore, the cross-sectional shape of the BSO seed crystal in step (2) is circular, rectangular, square, or the desired shape.
[0019] Furthermore, the platinum crucible described in step (2) has a thickness of 0.1~0.3mm, and is cylindrical, square, trapezoidal or other desired shapes, with a seed well at the bottom for placing seed crystals.
[0020] Furthermore, the crystal furnace is equipped with multiple equivalent workstations, enabling the simultaneous growth of more than five crystals.
[0021] The working principle of the technical solution of the present invention is as follows:
[0022] This invention aims to achieve 1.54µm laser characteristics in BSO crystals through Er₂O₃ doping. Rare-earth doping can provide corresponding luminescent centers for the matrix crystal, thereby obtaining laser output in various wavelength bands. For example, Yb-doped BSO crystals exhibit good absorption and excitation properties at 975nm and 1033nm, respectively; Tm-doped BSO crystals achieve a continuous wave with a wavelength of approximately 1.9µm and a maximum output power of 65mW; and Ho-doped BSO crystals achieve a 2.1µm laser output under 1.9µm laser pumping, etc.
[0023] This invention proposes a growth process for erbium-doped BSO single crystals by suppressing component separation through a crucible lowering method. This method suppresses component volatilization and separation, and is a practical BSO crystal growth method. Currently, this growth method has been proven through years of growth experiments by our research group to be a mature and effective crystal growth method for growing pure component and doped BSO crystals. In previous cases, BSO crystals with various doped ions, including Eu, Yb, Dy, and Ho, have been successfully grown. However, the growth of large-size Er-doped BSO crystals using the crucible lowering method has not yet been reported.
[0024] The advantages of the technical solution of the present invention are as follows:
[0025] 1) The temperature field is stable and the components are not easily volatilized. Compared with other rare earth ion-doped BSO crystals, the grown Er:BSO crystal has better integrity, transmittance of over 80%, and lower laser loss.
[0026] 2) The growth direction, size and shape of the crystals are easy to control. The segregation coefficient of Er:BSO fluctuates less with the change in concentration. Large crystals are less prone to cracking, resulting in a high yield.
[0027] 3) The process equipment is simple and easy to operate. Er:BSO has a Mohs hardness of 5 and a melting point of 1030℃. It is moderately soft and hard, with low energy consumption and production and processing costs, making it suitable for large-scale production by enterprises.
[0028] 4) Compared with Ho and Tm plasmas, Er:BSO crystals have stronger absorption characteristics at 980nm, which is highly matched with commercial laser diode pump sources and is expected to achieve more efficient excitation. Attached Figure Description
[0029] Figure 1 It is an optical wafer processed from BSO crystals with erbium doping of 0.5~2 at.% grown using the method of this invention.
[0030] Figure 2 The XRD diffraction pattern is that of BSO powder with erbium doping of 0.5~2 at.%.
[0031] Figure 3 The transmission spectrum is of BSO crystal with erbium doping of 0.5~2 at.%.
[0032] Figure 4 This is an absorption cross-section diagram of a BSO crystal with erbium doping of 0.5~2 at.%.
[0033] Figure 5 This is an emission cross-section diagram of a BSO crystal with erbium doping of 0.5~2 at.%. Detailed Implementation
[0034] The following detailed description illustrates the specific implementation method:
[0035] An erbium-doped bismuth silicate laser crystal, characterized in that the bismuth silicate crystal is doped with Er. 3+ Er 3+ The bismuth silicate crystal is doped in the form of Er₂O₃ at a doping concentration of 0.5–2 at.%, and its molecular formula is Bi₄Si₃O₃. 12 In this embodiment, the preferred Er₂O₃ doping concentration is 1 at.%.
[0036] The following examples illustrate specific embodiments of the present invention. However, these examples are merely for illustrative purposes and do not limit the scope of the invention in any way. Unless otherwise specified, the equipment components involved in the following examples are conventional equipment components; and unless otherwise specified, the industrial raw materials involved are commercially available conventional industrial raw materials.
[0037] Example 1
[0038] An erbium-doped bismuth silicate laser crystal and its preparation method, comprising the following steps:
[0039] 4N purity SiO2 and Bi2O3 raw materials were weighed and mixed according to stoichiometric ratio, ground and mixed evenly, and sintered at 850℃ for 8 hours to obtain Bi4Si3O 12Polycrystalline material was prepared by adding 0.5 at.% Er₂O₃, grinding and mixing thoroughly, and then loading it into a columnar Pt crucible with a seed crystal. The crucible thickness was 0.2 mm. Five identical crucibles were placed in a descending furnace, adjusted to an appropriate height, and the furnace temperature was set at 1150 °C. After material preparation and seeding, the growth rate was 0.3 mm / h. After growth, the crucibles were cooled to room temperature and then peeled off to obtain five cylindrical erbium-doped bismuth silicate crystals.
[0040] Example 2
[0041] A method for preparing an erbium-doped bismuth silicate laser crystal includes the following steps:
[0042] 4N purity SiO2 and Bi2O3 raw materials were weighed and mixed according to stoichiometric ratio, ground and mixed evenly, and sintered at 850℃ for 8 hours to obtain Bi4Si3O 12 Polycrystalline material was mixed with 1 at.% Er₂O₃, ground until homogeneous, and then placed into a square columnar Pt crucible with a seed crystal. The crucible thickness was 0.3 mm. The material was melted, seeded, and grown in a descending furnace at 1150 °C at a growth rate of 0.3 mm / h. After growth, the material was cooled to room temperature and the crucible was removed to obtain square columnar erbium-doped bismuth silicate crystals.
[0043] Example 3
[0044] A method for preparing an erbium-doped bismuth silicate laser crystal includes the following steps:
[0045] 4N purity SiO2 and Bi2O3 raw materials were weighed and mixed according to stoichiometric ratio, ground and mixed evenly, and sintered at 850℃ for 8 hours to obtain Bi4Si3O 12 Polycrystalline material; add 1.5 at.% Er2O3, grind and mix evenly, and load into a columnar Pt crucible with seed crystal. The crucible thickness is 0.2 mm and the crucible diameter is 2 inches. The material is melted, seeded, and grown in a descending furnace at 1150°C at a growth rate of 0.2 mm / h. After growth, the material is cooled to room temperature and the crucible is peeled off to obtain a cylindrical erbium-doped bismuth silicate crystal with a diameter of 2 inches.
[0046] Example 4
[0047] A method for preparing an erbium-doped bismuth silicate laser crystal includes the following steps:
[0048] 4N purity SiO2 and Bi2O3 raw materials were weighed and mixed according to stoichiometric ratio, ground and mixed evenly, and sintered at 850℃ for 8 hours to obtain Bi4Si3O 12Polycrystalline material was prepared by adding 2 at.% Er₂O₃, grinding and mixing thoroughly, and then loading it into a 1-inch diameter cylindrical Pt crucible. A BSO seed crystal was pre-installed at the bottom of the crucible, and the crucible thickness was 0.2 mm. Six identical crucibles were prepared, loaded, and placed at an appropriate height in a descending furnace. The furnace temperature was set at 1150°C. Heating, melting, and seeding were performed, followed by descending at a rate of 0.3 mm / h. After growth, the crucibles were cooled to room temperature. After removing the crucibles, six 1-inch diameter erbium-doped bismuth silicate crystals were obtained.
[0049] The bismuth silicate (Bi4Si3O) prepared in the examples of this invention 12 The fluorescence spectra of the mid-infrared laser crystal (BSO) are shown in the following comparison diagram. Figure 4 For Er 3+ Absorption cross-section pattern of BSO crystal. Figure 5 For Er 3+ Emission cross-section pattern of the BSO doped crystal. The above results indicate that the bismuth silicate crystal prepared in this invention is a laser crystal material with near-infrared emission characteristics.
[0050] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics of the solutions is not described in detail here. It should be noted that those skilled in the art can make various equivalent modifications or substitutions without departing from the structure of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.
Claims
1. A method for preparing an erbium-doped bismuth silicate laser crystal material, characterized in that: The bismuth silicate crystal material is doped with Er 3+ wherein Er 3+ is doped in the form of Er2O3, the doping amount is 0.5-2 at.%, and the molecular formula of the bismuth silicate crystal is Bi4Si3O 12 .
2. The erbium-doped bismuth silicate laser crystal material according to claim 1, characterized in that: Er2O3 doping concentration is 0.5~2 at.%.
3. A method for preparing an erbium-doped bismuth silicate laser crystal material according to any one of claims 1-2, characterized in that... Includes the following steps: 1) Select high-purity SiO2 and Bi2O3 raw materials, prepare them according to the stoichiometric ratio, and use solid-state sintering method to sinter at 780~800℃ for 8~12 hours to obtain Bi4Si3O 12 Polycrystalline material; according to the stated doping amount, to Bi4Si3O 12 Er₂O₃ was added to the polycrystalline material, ground and mixed evenly, and then sintered at around 830℃ for 12 hours to obtain erbium-doped Bi₄Si₃O₃. 12 Polycrystalline material; 2) Select a bismuth silicate seed crystal, fix the seed crystal in the seed well area at the bottom of the crucible, and load the synthesized doped polycrystalline material into the area fixed with Bi4Si3O. 12 Place the seed crystal in the crucible and seal it, then move it into the ceramic tube at an appropriate height. 3) Heat the crystal furnace to 1080-1150℃ in 15-20 hours and hold for 6-10 hours; gradually raise the ceramic lead tube, and inoculate after the polycrystalline material in a certain area above the seed crystal melts, and hold for 3 hours; 4) Move the ceramic down-lead or heating element downward at a speed of 0.2~0.5 mm / h to grow the crystal and obtain the erbium-doped bismuth silicate laser crystal.
4. The method for preparing erbium-doped bismuth silicate laser crystal material according to claim 3, characterized in that: The purity of the initial raw material is 99.999%.
5. The method for preparing an erbium-doped bismuth silicate laser crystal material according to claim 3, characterized in that: In step 2), the orientation of the BSO seed crystal can be... <001> , <010> , <100> Direction or any other direction.
6. The method for preparing an erbium-doped bismuth silicate laser crystal material according to claim 3, characterized in that: In step 2), the cross-sectional shape of the seed crystal is circular, rectangular, square, or the desired shape.
7. The erbium-doped bismuth silicate laser crystal material according to claim 3, characterized in that: The crucible used for crystal growth is a platinum crucible with a wall thickness of 0.15~0.3mm and a shape that is cylindrical, rectangular, square, wedge-shaped or the desired shape.
8. The method for preparing an erbium-doped bismuth silicate laser crystal material according to claim 3, characterized in that: The crystal furnace is equipped with multiple equivalent workstations, which can grow more than 5 crystals at the same time.
9. The method for preparing an erbium-doped bismuth silicate laser crystal material according to claim 3, characterized in that: The rare earth ions used for doping can also be Ho. 3+ Or Yb 3+ Or Tm 3+ .