CN102888655A - Middle-infrared laser gain medium codoped bivalent chromium and cobalt ion II-VI crystal - Google Patents

Abstract

The invention relates to a preparation method of a middle-infrared laser gain medium codoped bivalent chromium and cobalt ion II-VI crystal and a laser output experiment device constructed based on the crystal, belonging to the field of all solid-state laser media. The laser gain medium codoped bivalent chromium and cobalt ion II-VI crystal is prepared through a method of arranging dopants at both ends of an ampoule and performing vacuum heat diffusion transmission or a method of plating dopant films at both sides of a crystal and performing vacuum heat diffusion transmission, and pumping is performed by utilizing the overlapped absorption wavelength of bivalent chromium and cobalt codoped ions, so that the two ions can be simultaneously excited, thereby obtaining middle-infrared wide-spectrum tunable laser output. The laser output experiment device provided by the invention uses the codoped bivalent chromium and cobalt ion II-VI crystal as the laser output medium, and can realize the middle-infrared wide-spectrum tunable laser output of 1.6-4.2 mu m.

Description

Mid-infrared laser gain medium double-doped divalent chromium and cobalt ions Ⅱ-Ⅵ crystal

technical field

The invention relates to all-solid-state laser gain medium technology, in particular to a method for preparing mid-infrared wide-spectrum tunable laser gain medium doubly doped with divalent chromium and cobalt ion II-VI crystals, belonging to the field of all-solid-state laser medium. the

Background technique

With the development of various optical testing techniques, there is an increasing demand for versatile and inexpensive mid-infrared laser sources. The wavelength of mid-infrared lasers can cover the "molecular fingerprint region", which has a wide range of uses, including atmospheric remote sensing testing, non-invasive medical diagnosis, lidar, oil exploration and various military applications such as target calibration, troubleshooting and infrared countermeasures . the

The light sources that can realize laser output in the mid-infrared band mainly include: CO ₂ gas lasers, whose output wavelength is 10-12 μm, lead-salt heterojunction lasers, whose output wavelength is 3-30 μm, and quantum cascade semiconductor lasers, whose output wavelength is greater than or equal to 3.7 μm, or a light source that realizes laser output in the mid-infrared band through a relatively complex nonlinear optical conversion technology, such as difference frequency oscillation laser (DFG), optical parametric oscillation laser (OPO), etc. However, the above mid-infrared laser sources have encountered basic problems that limit their use as durable, low-cost mid-infrared laser sources. For example, CO ₂ gas laser equipment is complex and huge, and both difference frequency oscillation lasers and optical parametric oscillation lasers need to be used. Expensive optics, and unstable; lead-salt heterojunction lasers and quantum cascade semiconductor lasers have low laser output power. Therefore, the drawbacks of the above-mentioned laser sources have so far prevented their use in high-power applications such as remote sensing testing.

In contrast to the above-mentioned laser light sources, all-solid-state lasers based on transition metal ion (TM ²⁺ ) doped II-VI crystals ZnS, ZnSe, CdS, and CdSe are gradually becoming broadband tunable, high-power, and highly stable A mid-infrared laser light source. The detailed research on II-VI crystals doped with transition metal ions (TM ²⁺ ), such as Cr ²⁺ , Co ²⁺ , and Fe ²⁺ , began in the 1960s. Transition metal ions will form deep energy levels in the energy gap after entering the semiconductor, and there will also be multiple valence states. Therefore, this impurity ion was regarded as the "nemesis" of fluorescence in early studies. This is why, despite considerable interest in transition metal ion-doped II-VI crystals, their lasing effects were not reported until the 1990s. In the mid-1990s, De Loach et al. (LD DeLoach, RH Page, GD Wilke, SA Payne, WF Krupke, Transition metal-doped zinc chalcogenides: Spectroscopy and laser demonstration of a new class of Lawrence Livermore National Laboratory of the United States) gain media, Journal Name: IEEE Journal of Quantum Electronics; Journal Volume: 32; Journal Issue: 6; Other Information: PBD: Jun 1996, (1996) Medium: X; Size: pp. 885-895.) first reported A breakthrough in the research of II-VI crystals doped with transition metal ions: They studied the absorption and emission properties of various zinc chalcogenides doped with Cr ²⁺ , Co ²⁺ , Ni ²⁺ and Fe ²⁺ , and believed that Such compounds have great potential as mid-infrared laser media, and based on Cr ²⁺ :ZnSe and Cr ²⁺ :ZnS, a laser output of 2.4 μm has been achieved at room temperature.

Commonly used II-VI crystals mainly include ZnS and ZnSe. II-VI crystals have excellent thermomechanical properties, strong thermal shock resistance and excellent thermal conductivity, which provide the necessary conditions for the high-power application of transition metal ion-doped II-VI crystal lasers. the

As for the spectral and lasing properties, transition metal ion doped II-VI crystals are very close to those of titanium-doped sapphire (Ti-S) lasers. It can be expected that, similar to Ti:sapphire lasers, transition metal ion-doped II-VI crystals will be able to emit light through a variety of oscillation modes, and have the advantage of direct pumping with InGaAsP or InGaNAs diode arrays. Computational study of multiple state energy levels by Fazzio et al. and experimental study on the low decay of V ²⁺ , Cr ²⁺ , Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ ions doped in ZnS and ZnSe The verification of energy levels explains why most of the researches focus on Cr ²⁺ , Co ²⁺ , Fe ²⁺ ions. The spectral ranges of Cr ²⁺ , Co ²⁺ , and Fe ²⁺ ions are 2-3 μm, 2.6-4 μm, and 3.7-5.2 μm, respectively, and have a wide tunable range. Sources from these lasers represent the simplest and most affordable mid-infrared laser sources available today.

Although the II-VI laser medium doped with transition metal ions has been studied in depth, the use of double-doped or multi-doped transition metal ions doped into II-VI crystals to increase the range of laser tunable laser gain media Research has rarely covered it. the

Contents of the invention

The purpose of the present invention is to provide a method for preparing a mid-infrared wide-spectrum tunable laser gain medium double-doped divalent chromium and cobalt ion II-VI crystal; the double-doped divalent chromium and cobalt ion II-VI crystal is Using the double-ended dopant vacuum thermal diffusion transmission method of the ampoule, or the vacuum thermal diffusion transmission method of the dopant film on both sides of the crystal; and then pumping through the overlapping absorption wavelength of the bivalent chromium and cobalt double doping ions, it can Simultaneously realize the excitation of two kinds of ions, so as to obtain mid-infrared broad-spectrum tunable laser gain medium-double-doped divalent chromium and cobalt ion II-VI crystal. The invention provides that the novel doped crystal is fully expected to become an ideal broadband mid-infrared tunable laser gain medium. the

Another object of the present invention is to provide a laser output experimental device based on a mid-infrared wide-spectrum tunable laser gain medium doped with divalent chromium and cobalt ion II-VI crystals. The experimental device uses double-doped divalent chromium With cobalt ion Ⅱ-Ⅵ crystal as the laser output medium, the tunable laser output in the mid-infrared wide spectral band of 1.6-4.2 μm can be realized. the

In order to achieve the above object, the present invention is realized by adopting the technical scheme constituted by the following technical measures. the

The invention discloses a method for preparing a mid-infrared laser gain medium double-doped divalent chromium and cobalt ion II-VI crystal, which is characterized in that the double-doped divalent chromium and cobalt ion II-VI crystals are prepared by using an ampoule double-ended dopant vacuum thermal diffusion transmission method. Cobalt ion II-VI crystals, including the following specific process steps:

(1) Place the Ⅱ-Ⅵ crystal thin disc in the middle of a quartz ampoule composed of three quartz tubes with a large middle and small ends. Take simple Co powder and simple Cr powder and place them at both ends of the quartz ampule. And the distances between the two elemental powders of Co and Cr and the Ⅱ-Ⅵ crystal thin discs are equal;

(2) The quartz ampoule composed of three sections of quartz tubes described in step (1) is bonded together at high temperature with an oxygen-hydrogen flame, and then sealed after vacuumizing to 10 ^-3 ~ 10 ^-5 Pa;

(3) Place the sealed quartz ampoule in step (2) in a high-temperature furnace heated by multiple sets of heating rods, and conduct thermal diffusion for 1 to 15 days at a temperature of 700-1300°C to obtain double-doped di Valence chromium and cobalt ion Ⅱ-Ⅵ crystal laser gain medium samples;

(4) Finally, the divalent chromium and cobalt ion II-VI crystal laser gain medium samples doped in step (3) are polished and cut to obtain a mid-infrared broad-spectrum tunable laser gain medium doped with Cr ²⁺ , Co ²⁺ : Ⅱ-Ⅵ crystal.

In the above solution, the II-VI crystal thin disc is ZnS, or ZnSe, or ZnTe, or CdS, or CdSe or CdTe crystal thin disc. the

In the above solution, the purity of the elemental cobalt powder and elemental chromium powder is above 99.99%; the purity of the II-VI crystal thin disk is above 99.999%. the

In the above scheme, the concentrations of the dopant ions are respectively 1×10 ¹⁸ cm ^-3 to 1×10 ²⁰ cm ^-3 for Cr ²⁺ and 1×10 ¹⁸ cm ^-3 to 1×10 ²⁰ cm for Co ^{2+ -3} .

The invention discloses a method for preparing a mid-infrared wide-spectrum tunable laser gain medium doped with divalent chromium and cobalt ion II-VI crystals, which is characterized in that double-doped crystals are prepared by using a double-sided chromium-plated film and cobalt film vacuum thermal diffusion method. Divalent chromium and cobalt ion II-VI crystals, including the following specific process steps:

(1) Use the sputtering method or evaporation method to coat the two crystal faces of the II-VI crystal wafer with a single Co film and a single Cr film respectively, and the film thickness of the two crystal faces is 100-500nm;

(2) Put the Ⅱ-Ⅵ crystal thin disc coated with film in step (1) into a quartz ampoule, vacuumize it to 10 ^-3 ~ 10 ^-5 Pa and seal it;

(3) Place the sealed quartz ampoule in step (2) in a high-temperature furnace heated by multiple sets of heating rods, and conduct thermal diffusion at a temperature of 700-1300°C for 1-15 days to obtain a double-doped Valence chromium and cobalt ion Ⅱ-Ⅵ crystal laser gain medium samples;

(4) Finally, polish and cut the divalent chromium and cobalt ion II-VI crystal laser gain medium sample doped in step (3), and then obtain a mid-infrared broad-spectrum tunable laser gain medium doped with Cr ²⁺ , Co ²⁺ : Ⅱ-Ⅵ crystal.

In the above solution, the II-VI crystal thin discs are ZnS, or ZnSe, or ZnTe, or CdS, or CdSe or CdTe crystal thin discs. the

In the above solution, the purity of the elemental cobalt thin film and elemental chromium thin film are both above 99.99%; the purity of the II-VI crystal thin disc is above 99.999%. the

In the above scheme, the concentrations of the dopant ions are respectively 1×10 ¹⁸ cm ^-3 to 1×10 ²⁰ cm ^-3 for Cr ²⁺ and 1×10 ¹⁸ cm ^-3 to 1×10 ²⁰ cm for Co ^{2+ -3} .

The present invention is a laser output experimental device based on a mid-infrared wide-spectrum tunable laser gain medium doped with divalent chromium and cobalt ion II-VI crystals, which is characterized in that it includes a laser pump source, a pump beam, a sealed box, Sealed optical hole, input cavity mirror, laser gain medium, output cavity mirror, output laser beam; the pump beam output from the laser pump source enters the input cavity mirror through the sealed optical hole of the sealed box, and the pump beam passes through the input cavity The mirror reaches the laser gain medium, and the gain medium produces light conversion to realize light amplification, and then to the output cavity mirror, and the laser light passing through the output cavity mirror outputs the laser light speed through the sealed optical hole. the

In the above scheme, the wavelength of the pumping beam is 1.4-1.8 μm; the wavelength of the output laser beam is 1.6-4.2 μm. In order to make the pumping beam fully transmit and the output laser is totally reflected, the input cavity mirror is coated; in order to make the output laser beam More than 90% reflection, the output cavity mirror is also coated. the

The characteristics and beneficial technical effects of the present invention are as follows:

The present invention utilizes divalent chromium and cobalt ions to double-dope II-VI crystals to obtain an ideal mid-infrared wide-band tunable laser gain medium; the obtaining method has simple process steps and is easy to operate and realize; it has a mid-infrared wide-band band The laser output experimental device constructed by the Cr ²⁺ and Co ²⁺ double-doped Ⅱ-Ⅵ crystal of the tuned laser gain medium can output 1.6-4.2 μm mid-infrared wide-spectrum tunable laser; thus it can greatly increase the laser tunable laser Gain medium range.

The basic principle of the present invention is to prepare Cr ²⁺ and Co ²⁺ double-doped II by using the method of vacuum thermal diffusion transmission of dopants at both ends of the ampoule, or by using the method of vacuum thermal diffusion transmission of dopant films on both sides of the crystal. -VI crystal; the gain medium is pumped by the overlapping absorption wavelength of divalent chromium and cobalt double-doped ions, and the two ions can be excited and excited at the same time, so as to obtain a 1.6-4.2 μm mid-infrared broad-spectrum tunable laser output . Due to the 1.6-4.2μm mid-infrared broad-spectrum tunable laser gain medium of Cr ²⁺ and Co ²⁺ double-doped II-VI crystal laser gain medium, in this laser medium, ^{the 5} E of Cr ²⁺ → ⁵ T ₂ The transition absorption wavelength 1.4～1.8 μm and ^{the 4} A ₂ (F)→ ⁴ T ₁ (F) transition absorption wavelength 1.2～2.0 μm of Co ²⁺ have an overlapping band 1.4～1.8 μm, so use a certain The wavelength, such as 1.55 μm, can realize the excitation of two kinds of ions at the same time by pumping; the fluorescence spectrum range of Cr ²⁺ is 1.6-2.8 μm, and the fluorescence spectrum of Co ²⁺ is 2.6-4.2 μm, thus obtaining 1.6- 4.2μm wide spectrum tunable laser output. The interaction between the doped Cr ²⁺ and Co ²⁺ ions and the surrounding ions is relatively strong, and their electronic state parameters are closely related to the crystal. Different crystals lead to different tunable laser output ranges. Specifically, the tunable laser output range of Cr ²⁺ , Co ²⁺ : ZnS is 1.6-3.6 μm, that of Cr ²⁺ , Co ²⁺ : ZnSe is 1.8-3.8 μm, and that of Cr ²⁺ , Co ²⁺ : CdS is 2.0 ～3.9 μm, Cr ²⁺ , Co ²⁺ : CdSe is 2.2～4.2 μm.

Description of drawings

Figure 1 In Example 1 and Example 2 of the present invention, the mid-infrared wide-spectrum tunable laser gain medium was prepared by using the double-terminal dopant vacuum thermal diffusion transfer method in the quartz ^ampoule . ²⁺ :ZnSe crystal and Cr ²⁺ ,Co ²⁺ :CdS crystal process diagram;

Fig. 2 In Example 3 and Example 4 of the present invention, the mid-infrared wide-spectrum tunable laser gain medium was prepared by double-sided dopant film coating vacuum thermal diffusion transfer method in the present invention ^{. 2+} :ZnTe crystal and Cr ²⁺ ,Co ²⁺ :CdTe crystal process diagram;

Fig. 3 is a schematic diagram of the structure of a laser output experimental device constructed based on a mid-infrared wide-spectrum tunable laser gain medium divalent chromium and cobalt ions double-doped Cr ²⁺ , Co ²⁺ : ZnSe crystal according to Example 5 of the present invention.

In the figure, 1 Co powder, 2 heating rod, 3 quartz ampoule, 4 crystal thin disc, 5 Cr powder, 6 Cr thin film, 7 Co thin film, 8 laser pump source, 9 pump beam, 10 sealed box, 11 sealed Optical hole, 12 input cavity mirrors, 13 laser gain medium, 14 output cavity mirrors, 15 output laser beams. the

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments, but it does not mean any limitation to the protection content of the present invention. the

Example 1:

Preparation of Cr ²⁺ , Co ²⁺ : ZnSe Crystals by Vacuum Thermal Diffusion Transport of Ampoule Double-terminal Dopants

In this example, Cr ²⁺ , Co ²⁺ : ZnSe is selected as the raw material for preparing Cr ²⁺ , Co ²⁺ : ZnSe crystal, elemental chromium powder and cobalt powder with a purity of more than 99.99%, and ZnSe crystal with a purity of more than 99.999%.

In this example, select the elemental Cr powder 5 and the elemental Co powder 1 whose purity is more than 99.99%, and the ZnSe crystal wafer 4 whose purity is more than 99.999% as the preparation of Cr ²⁺ , Co ²⁺ : ZnSe double-doped Crystal raw material.

First, a thin ZnSe crystal disc 4 with a diameter of 2 cm and a thickness of 0.2 cm was placed in the middle of a quartz ampoule 3 composed of three quartz tubes with a large middle and small ends, and then the elemental Co powder 1 and the elemental Cr The powder 5, each of which weighs 0.1 g, is respectively placed at the two ends of the quartz ampoule 3, and the elemental Co powder and the elemental Cr powder at the two ends of the quartz ampoule 3 are respectively placed between the ZnSe crystal thin disc in the middle of the quartz ampoule 3 The distances are equal, and then the three sections of quartz tubes are glued together at high temperature by hydrogen-oxygen flame, and sealed after being vacuumed to 10 ^-5 Pa, as shown in Figure 1; the sealed quartz ampoule 3 is placed in the In a high-temperature furnace heated by multiple sets of heating rods 2, thermal diffusion was performed at a temperature of 700°C for 15 days to obtain a double-doped Cr ²⁺ , Co ²⁺ :ZnSe crystal laser gain medium sample, and the concentration of doped ions was respectively Cr ²⁺ is 1×10 ¹⁸ cm ^-3 , Co ²⁺ is 1×10 ¹⁸ cm ^-3 ~ 1×10 ¹⁸ cm ^-3 ; finally the double doped Cr ²⁺ , Co ²⁺ : The ZnSe crystal laser gain medium sample is polished and cut to obtain a laser gain medium Cr ²⁺ , Co ²⁺ : ZnSe crystal with excellent texture.

Example 2:

Preparation of Cr ²⁺ , Co ²⁺ :CdS Crystals by Vacuum Thermal Diffusion Transport of Dopants in Ampoule

In this example, the elemental Cr powder 5 and the elemental Co powder 1 with a purity of more than 99.99% and the CdS crystal wafer 4 with a purity of more than 99.999% are selected as the preparation of Cr ²⁺ , Co ²⁺ :CdS double-doped crystal raw materials.

First, a thin CdS crystal disc 4 with a diameter of 2 cm and a thickness of 0.2 cm was placed in the middle of a quartz ampoule 3 composed of three quartz tubes with a large middle and small ends, and then the elemental Co powder 1 and the elemental Cr The powders 5, each weighing 0.3 g, are respectively placed at the two ends of the quartz ampoule 3, and the placement positions of the simple substance Co powder and the simple substance Cr powder at the two ends of the quartz ampoule 3 are respectively in the middle of the CdS crystal wafer 4 in the middle of the quartz ampoule 3. The distances between them are equal, and then the three sections of quartz tubes are glued together at high temperature by hydrogen-oxygen flame, and sealed after vacuumizing to 10 ^-5 Pa, as shown in Figure 1; the sealed quartz ampoule 3 is placed in In a high-temperature furnace heated by multiple sets of heating rods 2, thermal diffusion was performed at a temperature of 1300°C for 2 days to obtain a double-doped Cr ²⁺ , Co ²⁺ :CdS crystal laser gain medium sample. The concentration of doped ions was Cr ²⁺ is 1×10 ²⁰ cm ^-3 , Co ²⁺ is 1×10 ¹⁸ cm ^-3 ~ 1×10 ²⁰ cm ^-3 ; finally the double doped Cr ²⁺ , Co ²⁺ :CdS crystal laser gain medium samples were polished and cut to obtain Cr ²⁺ , Co ²⁺ :CdS crystals with good quality laser gain medium.

Example 3:

Preparation of Cr ²⁺ , Co ²⁺ : ZnTe Crystals by Vacuum Thermal Diffusion Transport Method of Dopant Thin Films Plated on Both Sides of Crystals

In this example, the elemental Cr powder 5 and the elemental Co powder 1 with a purity of more than 99.99% and the ZnTe crystal wafer 4 with a purity of more than 99.999% are selected as the preparation of Cr ²⁺ , Co ²⁺ : ZnTe double-doped crystal raw materials.

Firstly, the two crystal surfaces of the thin ZnTe crystal wafer 4 with a diameter of 2 cm and a thickness of 2 mm were coated with an elemental Co thin film 7 and a Cr thin film 6 respectively by sputtering coating method, and the coating thickness was 100 nm. The wafer 4 is put into the quartz ampoule 3, the quartz ampoule 3 is evacuated to about 10 ^-5 Pa, and then sealed, as shown in Figure 2; the sealed quartz ampoule 3 is placed in a high temperature heated by multiple sets of heating rods 2 In the furnace, under the condition of 900 ℃ thermal diffusion for 13 ^days , double-doped Cr ²⁺ , Co ²⁺ :ZnTe crystal laser gain medium samples were obtained, and the concentration of doped ions was 1×10 ²⁰ cm ^-3 , Co ²⁺ is 1×10 ²⁰ cm ^-3 ; finally, the doped double-doped Cr ²⁺ , Co ²⁺ :ZnTe crystal laser gain medium sample is polished and cut to obtain a laser with excellent texture Gain medium Cr ²⁺ , Co ²⁺ : ZnTe crystal.

Example 4:

Preparation of Cr ²⁺ , Co ²⁺ : CdTe Crystals by Vacuum Thermal Diffusion Transport Method of Dopant Thin Films Plated on Both Sides of Crystals

In this example, elemental Cr powder 5 and elemental Co powder 1 with a purity of more than 99.99% and a CdTe crystal with a purity of more than 99.999% were selected as raw materials for preparing Cr ²⁺ , Co ²⁺ :CdTe double-doped crystals.

Firstly, the two crystal surfaces of a thin CdTe crystal wafer 4 with a diameter of 2 cm and a thickness of 2 mm were coated with an elemental Co thin film 7 and a Cr thin film 6 respectively by evaporation method, and the coating thickness was 500 nm. The wafer 4 is put into the quartz ampoule 3, the quartz ampoule 3 is evacuated to about 10 ^-5 Pa, and then sealed, as shown in Figure 2; the sealed quartz ampoule 3 is placed in a high temperature heated by multiple sets of heating rods 2 In the furnace, the temperature is 1300 ℃ under the condition of thermal diffusion for 1 day, and the double-doped Cr ²⁺ , Co ²⁺ :CdTe crystal laser gain medium sample is obtained, and the concentration of the doping ions is respectively 1×10 Cr ^{2+ 20} cm ^-3 , Co ²⁺ is 1×10 ²⁰ cm ^-3 ; finally, the doped double-doped Cr ²⁺ , Co ²⁺ :CdTe crystal laser gain medium sample is polished and cut to obtain a laser with excellent texture Gain medium Cr ²⁺ , Co ²⁺ : CdTe crystal.

The present invention is a laser output experimental device based on a mid-infrared wide-spectrum tunable laser gain medium doped with divalent chromium and cobalt ion II-VI crystals, as shown in Figure 3, including a laser pumping source 8 and a pumping beam 9. Sealed box 10, sealed optical hole 11, input cavity mirror 12, laser gain medium 13, output cavity mirror 14, output laser beam 15; the pump beam 9 output from the laser pump source 8 passes through the seal of the sealed box 10 The optical hole 11 enters the input cavity mirror 12, and the pump beam 9 reaches the laser gain medium 13 made of doubly doped bivalent chromium and cobalt ion II-VI crystal through the input cavity mirror 12, and then goes to the output cavity mirror 14, and passes through the output cavity mirror 12. The laser light from the cavity mirror 14 outputs a laser beam 15 through the sealed light hole 11 . the

Embodiment 5:

In the present invention, one of the high-quality laser gain medium Cr ²⁺ , Co ²⁺ : ZnSe crystal obtained by the above preparation method is used as the laser output experimental device to study the absorption spectrum and emission spectrum; here, the specific Cr ²⁺ , Co ²⁺ : the pump wavelength of ZnSe crystal is 1.55 μm, Cr ²⁺ , Co ²⁺ : the emission wavelength of ZnSe crystal is 1.8～3.7 μm. A flat concave cavity is selected as the laser resonator mirror, and a semiconductor laser (LD) is used as the pumping source for pumping to achieve a tunable mid-infrared laser output of 1.8-3.7 μm. Taking the output laser with a wavelength of 3.2 μm as an example, the laser resonator system is designed. As shown in Figure 3, the wavelength of the laser pump source 8 is 1.55 μm, and the output pump beam 9 is coated with the input cavity mirror 12, which is completely transparent to 1.55 μm and totally reflective to 3.2 μm wavelength light. The laser gain medium 13 is Cr ²⁺ , Co ²⁺ : ZnSe, the output cavity mirror 14 is coated with a film, which reflects 90% of the wavelength of 3.2 μm, and the output wavelength of the output laser 15 is 3.2 μm. It is worth noting that when the output laser is selected to have an output wavelength near 2.9 μm, it is in the strong absorption band of water. Therefore, it is necessary to exclude the influence of water vapor on the laser resonator in the laser experimental device. At this time, the laser resonator can be placed in a vacuum This effect can be eliminated by filling the laser resonator cavity with protective gas in the sealed box 10.

Claims (10)

1. A method for preparing a mid-infrared wide-spectrum tunable laser gain medium doped with divalent chromium and cobalt ion II-VI crystals, characterized in that the double-doped crystals are prepared by vacuum thermal diffusion transfer method of double-ended dopants in ampoules Divalent chromium and cobalt ion II-VI crystals, including the following specific process steps: (1) Place the II-VI crystal thin disc (4) in the middle of a quartz ampoule (3) composed of three quartz tubes with a large middle and small ends, and take the simple Co powder (1) and the simple Cr powder (5) respectively placed at both ends of the quartz ampoule (3), and the distances between the two elemental powders of Co and Cr and the thin wafers of II-VI crystals are equal; (2) The quartz ampoule (3) composed of three sections of quartz tubes described in step (1) is bonded together at high temperature with an oxygen-hydrogen flame, and sealed after vacuumizing to 10 ^-3 ~ 10 ^-5 Pa; (3) Place the sealed quartz ampoule (3) in step (2) in a high-temperature furnace heated by multiple sets of heating rods (2), and conduct thermal diffusion at a temperature of 700-1300°C for 1-15 days, The double-doped divalent chromium and cobalt ion Ⅱ-Ⅵ crystal laser gain medium sample is obtained; (4) Finally, the divalent chromium and cobalt ion II-VI crystal laser gain medium samples doped in step (3) are polished and cut to obtain a mid-infrared broad-spectrum tunable laser gain medium doped with Cr ²⁺ , Co ²⁺ : Ⅱ-Ⅵ crystal. 2. The preparation method of double-doped divalent chromium and cobalt ion II-VI crystal according to claim 1, characterized in that the II-VI crystal thin disc (4) is ZnS, or ZnSe, or ZnTe, or CdS, or CdSe or CdTe crystal thin discs. 3. The method for preparing double-doped divalent chromium and cobalt ion II-VI crystals according to claim 1, characterized in that the purity of the elemental cobalt powder (1) and elemental chromium powder (5) is above 99.99% ; The purity of the II-VI crystal thin disk (4) is above 99.999%. 4. The method for preparing double-doped divalent chromium and cobalt ion II-VI crystals according to claim 1 or 3, characterized in that the concentrations of the doped ions are respectively 1×10 ¹⁸ cm ^-3 for Cr ²⁺ ~1×10 ²⁰ cm ^-3 , Co ²⁺ is 1×10 ¹⁸ cm ^-3 ~1×10 ²⁰ cm ^-3 . 5. A method for preparing a mid-infrared wide-spectrum tunable laser gain medium doped with divalent chromium and cobalt ion II-VI crystals, characterized in that the dual-doped crystals are prepared by vacuum thermal diffusion of double-sided chromium-plated films and cobalt films Divalent chromium and cobalt ion II-VI crystals, including the following specific process steps: (1) Use the sputtering method or evaporation method to coat the two crystal faces of the II-VI crystal wafer (4) with an elemental Co film (7) and an elemental Cr film (6), respectively, and the film thickness of the two crystal faces is 100-500nm; (2) Put the II-VI crystal wafer (4) coated with film in step (1) into the quartz ampoule (3), vacuumize it to 10 ^-3 ~ 10 ^-5 Pa and seal it; (3) Place the sealed quartz ampoule (3) in step (2) in a high-temperature furnace, and conduct thermal diffusion at a temperature of 700-1300°C for 1-15 days to obtain double-doped divalent chromium and cobalt Ion Ⅱ-Ⅵ crystal laser gain medium sample; (4) Finally, the divalent chromium and cobalt ion II-VI crystal laser gain medium samples doped in step (3) are polished and cut to obtain a mid-infrared broad-spectrum tunable laser gain medium doped with Cr ²⁺ , Co ²⁺ : Ⅱ-Ⅵ crystal. 6. according to the preparation method of double-doped divalent chromium and cobalt ion II-VI crystal according to claim 5, it is characterized in that The II-VI crystal thin disc (4) is a ZnS, or ZnSe, or ZnTe, or CdS, or CdSe or CdTe crystal thin disc. 7. according to the preparation method of the described double-doped divalent chromium and cobalt ion II-VI crystal of claim 5, it is characterized in that The purity of the elemental cobalt thin film (7) and elemental chromium thin film (6) are both above 99.99%; the purity of the II-VI crystal thin disc (4) is above 99.999%. 8. The method for preparing double-doped divalent chromium and cobalt ion II-VI crystals according to claim 5 or 7, characterized in that the concentrations of the doped ions are respectively 1×10 ¹⁸ cm ^-3 for Cr ²⁺ ~1×10 ²⁰ cm ^-3 , Co ²⁺ is 1×10 ¹⁸ cm ^-3 ~1×10 ²⁰ cm ^-3 . 9. A mid-infrared wide-spectrum tunable laser gain medium double-doped divalent chromium and cobalt ion II-VI crystal laser output experimental device, characterized in that it includes a laser pump source (8), a pump beam (9 ), sealed box (10), sealed light hole (11), input cavity mirror (12), laser gain medium (13), output cavity mirror (14), output laser beam (15); from laser pumping source ( 8) The output pump beam (9) enters the input cavity mirror (12) through the sealed light hole (11) of the sealed box (10), and the pump beam (9) reaches the laser gain medium ( 13), and then to the output cavity mirror (14), the laser light passing through the output cavity mirror (14) then passes through the sealed light hole (11) to output the laser light speed (15). 10. The laser output experimental device according to claim 9, characterized in that the pump beam (9) has a wavelength of 1.4-1.8 μm; the output laser beam (15) has a wavelength of 1.6-4.2 μm; the input cavity mirror (12 ) and the output cavity mirror (14) are coated.

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