Near-infrared plasmon perovskite nanowire array laser and preparation method thereof

Abstract

The invention belongs to the field of nano photonics, laser technologies and photoelectric materials, and particularly discloses a near-infrared plasmon perovskite nanowire array laser and a preparation method thereof. The near-infrared plasmon perovskite nanowire array laser comprises a metal film substrate, a dielectric layer arranged on the metal film substrate and a perovskite nanowire / nanosheet array arranged on the dielectric layer, and the nanowire / nanosheet array provides optical gain and forms a resonant cavity of the laser; the perovskite nanowire / nanosheet array is excited through optical pumping, and laser emission of a near-infrared band is achieved. According to the near-infrared plasmon perovskite nanowire array laser, a metal plasmon effect local light field is utilized to break through the optical diffraction limit, high-efficiency and low-threshold near-infrared laser emission with the emission wave band being about 1 [mu] m is achieved, and the near-infrared plasmon perovskite nanowire array laser is suitable for the fields of on-chip light sources, biological sensing, optical communication and the like.

Description

Technical Field

[0001] The present invention belongs to the fields of nanophotonics, laser technology and optoelectronic materials, and specifically relates to a near-infrared plasmon perovskite nanowire array laser and a preparation method thereof. Background Art

[0002] Plasmon lasers can localize light fields and make ultra-small lasers that break through the optical diffraction limit. However, most near-infrared plasmon lasers are currently made of III-V semiconductor materials, and the manufacturing process is complex and costly, such as molecular beam epitaxy (MBE) and electron beam lithography (EBL). Low-dimensional metal halide perovskite materials have attracted widespread attention in the field of nanolasers due to their advantages of high absorption coefficient, high photoluminescence quantum yield, high defect tolerance, low Auger recombination rate, and low-cost manufacturing process. Tin-based perovskite material Cs 0.1 MA 0.9 SnI3 has a band gap of 1.3 eV and an emission wavelength of around 1 μm, making it a potential candidate for manufacturing low-cost, low-threshold near-infrared nanolasers.

[0003] However, there is little research on 0.1 MA 0.9 There are reports on the research of SnI3 plasmon laser. Therefore, it is of great significance to develop a laser with plasmon effect in the emission band near 1μm. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a near-infrared plasmon perovskite nanowire array laser with an emission wavelength of about 1 μm. The near-infrared plasmon perovskite nanowire array laser achieves high-efficiency, low-threshold, miniaturized near-infrared laser emission through a localized light field of the plasmon effect.

[0005] The second object of the present invention is to provide a method for preparing a near-infrared plasmon perovskite nanowire array laser.

[0006] The technical solution of the present invention to solve the above technical problems is: A near-infrared plasmon perovskite nanowire array laser comprises a metal film substrate, a dielectric layer arranged on the metal film substrate, and a perovskite nanowire / nanosheet array arranged on the dielectric layer, wherein the nanowire / nanosheet array provides optical gain of the laser and constitutes a resonant cavity of the laser; the perovskite nanowire / nanosheet array is excited by optical pumping to achieve laser emission in the near-infrared band.

[0007] As a preferred solution of the present invention, the material of the metal thin film substrate includes silver Ag or gold Au, and the thickness of the metal thin film substrate is 100 nm.

[0008] As a preferred solution of the present invention, the dielectric layer is subjected to surface modification treatment, the material of the dielectric layer includes magnesium fluoride MgF2 or aluminum oxide Al2O3, and the thickness of the dielectric layer is 10 nm.

[0009] As a preferred embodiment of the present invention, the perovskite nanowire / nanosheet array is an organic-inorganic hybrid perovskite material with a chemical formula of Cs 0.1 MA 0.9 SnI3.

[0010] As a preferred embodiment of the present invention, the perovskite nanowire array has a width of 4 μm, a length of 50 μm, and a height of 90 nm.

[0011] As a preferred embodiment of the present invention, the perovskite nanowire / nanosheet array is grown on the metal film substrate by PDMS nanoimprinting method.

[0012] As a preferred embodiment of the present invention, the pitch of the perovskite nanowire / nanosheet array is 10 μm.

[0013] As a preferred embodiment of the present invention, the wavelength of the optical pump is 400 nm, the repetition frequency is 1 KHz, the pulse width is 40 fs, and the power density is 200-400 μJ / cm².

[0014] As a preferred solution of the present invention, it also includes a protective layer arranged on the perovskite nanowire / nanosheet array, and the protective layer is a high molecular polymer film polymethyl methacrylate PMMA.

[0015] A method for preparing a near-infrared plasmon perovskite nanowire array laser comprises the following steps: Step S1: wipe the single crystal silicon substrate sample with a cotton swab dipped in detergent water; rinse the surface of the substrate sample with deionized water; ultrasonically clean the single crystal silicon substrate sample with deionized water for 20 min; immerse the single crystal silicon substrate sample in acetone solution for ultrasonic cleaning, the ultrasonic cleaning temperature is 50 ° C, and the ultrasonic cleaning time is 20 min; immerse the single crystal silicon substrate sample in isopropanol for 20 min of ultrasonic cleaning; after cleaning, use a nitrogen gun to blow dry the single crystal silicon substrate sample; finally, put the single crystal silicon substrate sample into an oven for drying, the drying temperature is 80 ° C, and after drying, take out the single crystal silicon substrate sample; Step S2: According to the standard startup steps, turn on the coating machine, put the single crystal silicon substrate sample to be evaporated into the sample holder, and put the material to be evaporated in the evaporation boat. Pump the evaporation chamber to a high vacuum state; control the metal deposition rate by adjusting the power of the evaporation source in the evaporation chamber or cavity, and use a film thickness monitor to monitor the thickness of the film in real time to ensure that the required specifications are met (the deposition thickness of the metal layer silver Ag is 100 nm, the deposition rate is 40Å / s, and the deposition thickness of the dielectric layer magnesium fluoride MgF2 is 10 nm, and the deposition rate is 1Å / s); after the coating is completed, open the evaporation chamber and take out the substrate sample; Step S3: immerse the substrate sample in OTS solvent and heat it at 70 °C for 20 min; then clean it with toluene and isopropanol in sequence, and then blow dry the surface of the substrate sample with nitrogen; Step S4: CsI, MAI, SnI2 and SnF2 were added to a mixed solution of DMF and DMSO at a molar ratio of x: (1-x): 1: 0.1, and stirred at 70 °C for 2 h to fully dissolve the precursors, thereby preparing a perovskite precursor solution: Step S5: prepare a PDMS solution according to the ratio of PDMS prepolymer to cross-linking agent of 10:1, perform vacuum degassing on the prepared PDMS solution, and then use a rubber-tipped dropper to drop the PDMS solution onto the silicon substrate sample with the nanowire array photolithography; use a coating machine to evenly spin-coat the PDMS solution onto the substrate sample; after spin coating, transfer the sample to a hot plate for heating at 90°C for 3 h; after heating, peel off the PDMS film and put it into a clean container for standby use; Step S6: Place the substrate sample on the operating table in the glove box, and use a pipette to drop 5 μL of the perovskite precursor solution on the surface of the coated substrate sample; then cover the surface of the substrate sample with a PDMS film; then anneal the sample at a temperature of 70 °C for 50 min; after annealing, place the sample in a clean container. Cover the container with tin foil with holes; then place the container in the glove box to dry naturally for 10 h; after drying, peel off the PDMS film; Step S7: 50 μL of PMMA solution was dropped onto the manufactured sample, and the PMMA solution was evenly spin-coated into a PMMA film using a coating machine at a set rate, and then the sample was heated and cured at a heating temperature of 70 °C for 10 min to obtain a laser sample; Step S8: Turn on the femtosecond laser, spectrometer and corresponding test software, place the laser sample on the stage, perform lasing spectrum test after focusing, adjust the power of the pump light through the attenuator to obtain the lasing spectrum under different pumping intensities, then draw the lasing spectrum, and calculate the laser threshold, half-width and quality factor.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The near-infrared plasmon perovskite nanowire array laser of the present invention can achieve lasing at room temperature, and the structure of the array can integrate more lasers or lasers of different wavelength bands on a chip.

[0017] 2. The near-infrared plasmon perovskite nanowire array laser of the present invention can achieve adjustable lasing peak in the 973-1023 nm band by regulating the components and preparation process, thus meeting the use requirements within this band.

[0018] 3. The near-infrared plasmon perovskite nanowire array laser of the present invention can be prepared by solution method and nanoimprinting method, avoiding the need for conventional near-infrared semiconductor lasers to use III-V group materials and high-cost molecular beam epitaxy, electron beam lithography and other methods in this band, thereby significantly improving production efficiency and reducing production costs.

[0019] 4. The near-infrared plasmon perovskite nanowire array laser of the present invention has the advantages of miniaturization, low threshold, high efficiency, and tunable wavelength, and is suitable for the fields of integrated photonics, biosensing, optical communication, and quantum information processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the near-infrared plasmon perovskite nanowire array laser of the present invention.

[0021] Figure 2 This is the laser lasing spectrum of the near-infrared plasmon perovskite nanowire array laser of the present invention, wherein the abscissa is wavelength (Wavelength), the unit is nm; the ordinate is intensity (Intensity), the unit is au.

[0022] Figure 3 For near-infrared perovskite material Cs 0.1 MA 0.9 Schematic diagram of the absorption spectrum and PL spectrum of SnI3, where the horizontal axis is wavelength (Wavelength), the unit is nm; the first vertical axis is absorbance (Absorbance), the unit is au; the second vertical axis is photoluminescence intensity (PL Intensity), the unit is au.

[0023] Figure 4 For near-infrared perovskite material Cs 0.1 MA 0.9 Schematic diagram of the XRD spectrum of SnI3, where the horizontal axis is the 2θ angle (2θ), the unit is degree; the vertical axis is the intensity (Intensity), the unit is au.

[0024] Figure 5 This is a schematic diagram of time-resolved photoluminescence spectroscopy (TRPL), where the horizontal axis is time (Time), the unit is ns; the vertical axis is intensity (Intensity), the unit is au.

[0025] Figure 6 It is a schematic diagram of the dual-pump response test of the near-infrared plasmon perovskite nanowire array laser of the present invention, wherein the horizontal axis is the delay time (Delay Time), the unit is ns; the vertical axis is the relative intensity (RelativeIntensity), the unit is au.

[0026] Figure 7 Schematic diagram of the relationship between the pump energy, lasing intensity and half-peak width of the near-infrared plasmon perovskite nanowire array laser of the present invention, wherein the abscissa is the pump intensity (Pump Influence), the unit is μJ cm -2 ; The first vertical axis is the emission intensity (Emission Intensity), the unit is au; the second vertical axis is the half maximum width (FWHM), the unit is nm.

[0027] Figure 8 Schematic diagram of the wavelength-intensity relationship of the near-infrared plasmon perovskite nanowire array laser of the present invention in the 973-1023 nm band, wherein the abscissa is wavelength (Wavelength), in nm; the ordinate is intensity (Intensity), in au. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0029] See also Figure 1-Figure 8 The near-infrared plasmon perovskite nanowire array laser of the present invention comprises a metal film substrate, a dielectric layer arranged on the metal film substrate, and a perovskite nanowire / nanosheet array arranged on the dielectric layer, wherein the nanowire / nanosheet array constitutes a resonant cavity of the laser; the perovskite nanowire / nanosheet array is excited by optical pumping to achieve laser emission in a near-infrared band with an emission band near 1 μm.

[0030] See also Figure 1-Figure 8 The metal film substrate is prepared by high vacuum resistance evaporation, and its materials include Ag and Au. The thickness of the metal film substrate is 80-120nm.

[0031] See also Figure 1-Figure 8 The material of the dielectric layer includes MgF2 and Al2O3, and the thickness of the dielectric layer is 5-15 nm.

[0032] See also Figure 1-Figure 8 The emission wavelength of the near-infrared plasmon perovskite nanowire array laser of the present invention is related to the components of the perovskite gain medium layer. In this embodiment, the emission wavelength of the near-infrared plasmon perovskite nanowire array laser of the present invention is 973-1023 nm, which belongs to the near-infrared band. In addition, the threshold power density of the near-infrared plasmon perovskite nanowire array laser of the present invention is lower than 300μJ / cm².

[0033] See also Figure 1-Figure 8 The perovskite nanowire / nanosheet array is an organic-inorganic hybrid perovskite material with a chemical formula of Cs 0.1 MA 0.9 SnI3.

[0034] See also Figure 1-Figure 8 The perovskite nanowire / nanosheet array is grown on the metal film substrate by PDMS nanoimprinting, wherein the diameter of the perovskite nanowire / nanosheet array is 1-4 μm, the length is 10-50 μm, the height is 50-100 nm, and the spacing of the perovskite nanowire / nanosheet array is 10-20 μm to ensure the maximization of the plasmon coupling effect.

[0035] In this embodiment, the plasmon resonance wavelength can be optimized by adjusting the geometric parameters of the nanowires or nanosheets in the perovskite nanowire / nanosheet array.

[0036] See also Figure 1-Figure 8 The wavelength of the optical pump is 400nm, the repetition frequency is 1KHz, the pulse width is 40fs, and the power density is 200-400μJ / cm².

[0037] See also Figure 1-Figure 8 The extension direction of the nanowires or nanosheets in the perovskite nanowire / nanosheet array is perpendicular or parallel to the metal film substrate, so as to regulate the directionality and mode characteristics of laser emission.

[0038] See also Figure 1-Figure 8, the near-infrared plasmon perovskite nanowire array laser of the present invention further comprises a protective layer disposed on the perovskite nanowire / nanosheet array to prevent material degradation and improve the stability of the near-infrared plasmon perovskite nanowire array laser of the present invention; In this embodiment, the protective layer is a high molecular polymer film polymethyl methacrylate (PMMA), whose refractive index is 1.49-1.50 in the visible light range and 1.48-1.49 in the near infrared band (900-1000 nm), which can effectively reduce light scattering and improve the stability of the device.

[0039] like Figure 2-Figure 8 As shown, Figure 2 The laser lasing spectrum of the near-infrared plasmon perovskite nanowire array laser of the present invention is as follows: Figure 2 It can be seen that the threshold power density of the near-infrared plasmon perovskite nanowire array laser of the present invention is lower than 300 μJ / cm²; Figure 3 For near-infrared perovskite material Cs 0.1 MA 0.9 Schematic diagram of the absorption spectrum and PL spectrum of SnI3, from Figure 3 It can be seen that the near-infrared perovskite material Cs 0.1 MA 0.9 SnI3 has good absorption characteristics and material luminescence properties in the short wavelength band; Figure 4 For near-infrared perovskite material Cs 0.1 MA 0.9 Schematic diagram of XRD spectrum of SnI3; Figure 5 is a schematic diagram of time-resolved photoluminescence spectroscopy (TRPL), which shows the stimulated emission lifetime of the near-infrared plasmon perovskite nanowire array laser of the present invention; Figure 6 It is a schematic diagram of a dual-pump response test of the near-infrared plasmon perovskite nanowire array laser of the present invention, which shows that the near-infrared plasmon perovskite nanowire array laser of the present invention has ultrafast dynamic characteristics; Figure 7 It is a schematic diagram of the relationship between the pump energy, lasing intensity and half-peak width of the near-infrared plasmon perovskite nanowire array laser of the present invention, which shows that the near-infrared plasmon perovskite nanowire array laser of the present invention has an ultra-low threshold and laser lasing characteristics; Figure 8 It is a schematic diagram of the wavelength-intensity relationship of the near-infrared plasmon perovskite nanowire array laser of the present invention in the 973-1023 nm band, which demonstrates the wavelength tunability of the near-infrared plasmon perovskite nanowire array laser of the present invention and that its lasing wavelength covers the near-infrared band.

[0040] See also Figure 1-Figure 8The method for preparing the near-infrared plasmon perovskite nanowire array laser of the present invention comprises the following steps: Step S1: wipe the single crystal silicon substrate sample with a cotton swab dipped in detergent water; rinse the surface of the substrate sample with deionized water; ultrasonically clean the single crystal silicon substrate sample with deionized water for 20 min; immerse the single crystal silicon substrate sample in acetone solution for ultrasonic cleaning, the ultrasonic cleaning temperature is 50 ° C, and the ultrasonic cleaning time is 20 min; immerse the single crystal silicon substrate sample in isopropanol for 20 min of ultrasonic cleaning; after cleaning, use a nitrogen gun to blow dry the single crystal silicon substrate sample; finally, put the single crystal silicon substrate sample into an oven for drying, the drying temperature is 80 ° C, and after drying, take out the single crystal silicon substrate sample; Step S2: According to the standard startup steps, turn on the coating machine, put the single crystal silicon substrate sample to be evaporated into the sample holder, and put the material to be evaporated in the evaporation boat. Pump the evaporation chamber to a high vacuum state; control the metal deposition rate by adjusting the power of the evaporation source in the evaporation chamber or cavity, and use a film thickness monitor to monitor the thickness of the film in real time to ensure that the required specifications are met (the deposition thickness of the metal layer silver Ag is 100 nm, the deposition rate is 40 Å / s, and the deposition thickness of the dielectric layer magnesium fluoride MgF2 is 10 nm, and the deposition rate is 1 Å / s); after the coating is completed, open the evaporation chamber and take out the substrate sample; Step S3: immerse the substrate sample in OTS solvent and heat it at 70 °C for 20 min; then clean it with toluene and isopropanol in sequence, and then blow dry the surface of the substrate sample with nitrogen; Step S4: CsI, MAI, SnI2 and SnF2 were added to a mixed solution of DMF and DMSO at a molar ratio of x: (1-x): 1: 0.1, and stirred at 70 °C for 2 h to fully dissolve the precursors, thereby preparing a perovskite precursor solution: Step S5: prepare a PDMS solution according to the ratio of PDMS prepolymer to cross-linking agent of 10:1, perform vacuum degassing on the prepared PDMS solution, and then use a rubber-tipped dropper to drop the PDMS solution onto the silicon substrate sample with the nanowire array photolithography; use a coating machine to evenly spin-coat the PDMS solution onto the substrate sample; after spin coating, transfer the sample to a hot plate for heating at 90°C for 3 h; after heating, peel off the PDMS film and put it into a clean container for standby use; Step S6: Place the substrate sample on the operating table in the glove box, and use a pipette to drop 5 μL of the perovskite precursor solution on the surface of the substrate sample; then cover the surface of the substrate sample with a PDMS film; then anneal the sample at 70 °C for 50 min; after annealing, place the sample in a clean container. Cover the container with tin foil with holes; then place the container in the glove box to dry naturally for 10 h; after drying, peel off the PDMS film; Step S7: 50 μL of PMMA solution was dropped onto the manufactured sample, and the PMMA solution was evenly spin-coated into a PMMA film using a coating machine at a set rate, and then the sample was heated and cured at a heating temperature of 70 °C for 10 min to obtain a laser sample; Step S8: Turn on the femtosecond laser, spectrometer and corresponding test software, place the laser sample on the stage, perform lasing spectrum test after focusing, adjust the power of the pump light through the attenuator to obtain the lasing spectrum under different pumping intensities, then draw the lasing spectrum, and calculate the laser threshold, half-width and quality factor.

[0041] The above is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited to the above content. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A near-infrared plasmon perovskite nanowire array laser, characterized in that: It includes a metal film substrate, a dielectric layer arranged on the metal film substrate, and a perovskite nanowire / nanosheet array arranged on the dielectric layer, wherein the nanowire / nanosheet array provides optical gain of the laser and constitutes a resonant cavity of the laser; the perovskite nanowire / nanosheet array is excited by optical pumping to achieve laser emission in the near-infrared band.

2. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: The material of the metal film substrate includes silver or gold, and the thickness of the metal film substrate is 80-120 nm.

3. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: The dielectric layer is surface-modified and its material includes magnesium fluoride or aluminum oxide. The thickness of the dielectric layer is 5-15 nm.

4. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: The perovskite nanowire / nanosheet array is an organic-inorganic hybrid perovskite material with a chemical formula of Cs 0.1 MA 0.9 SnI3.

5. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: The height of the perovskite nanowire / nanosheet array is 80-100 nm.

6. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: The perovskite nanowire / nanosheet array is grown on the metal film substrate by PDMS nanoimprinting method.

7. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: The pitch of the perovskite nanowire / nanosheet array is 1-10 μm.

8. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: The optical pump has a wavelength of 400 nm, a repetition rate of 1 KHz, a pulse width of 40 fs, and a power density of 200-400 μJ cm -2 .

9. The near-infrared plasmon perovskite nanowire array laser according to claim 1, characterized in that: It also includes a protective layer arranged on the perovskite nanowire / nanosheet array, and the protective layer is a high molecular polymer film polymethyl methacrylate PMMA.

10. A method for preparing the near-infrared plasmon perovskite nanowire array laser according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1: Wipe the single crystal silicon substrate sample with a cotton swab dipped in detergent water; Rinse the surface of the substrate sample with deionized water; ultrasonically clean the single crystal silicon substrate sample with deionized water for 20 min; immerse the single crystal silicon substrate sample in acetone solution for ultrasonic cleaning at a temperature of 50 °C for 20 min; immerse the single crystal silicon substrate sample in isopropanol for 20 min of ultrasonic cleaning; after cleaning, use a nitrogen gun to blow dry the single crystal silicon substrate sample; finally, put the single crystal silicon substrate sample into an oven for drying at a drying temperature of 80 °C; after drying, take out the single crystal silicon substrate sample; Step S2: Open the coating machine, put the single crystal silicon substrate sample to be evaporated into the sample holder, and put the material to be evaporated into the evaporation boat; evacuate the evaporation chamber to a high vacuum state; control the deposition rate of the metal by adjusting the power of the evaporation source in the evaporation chamber or cavity, and use a film thickness monitor to monitor the thickness of the film in real time to ensure that the required specifications are met; after the coating is completed, open the evaporation chamber and take out the substrate sample; Step S3: immerse the substrate sample in OTS solvent and heat it at 70 °C for 20 min; then clean it with toluene and isopropanol in sequence, and then blow dry the surface of the substrate sample with nitrogen; Step S4: CsI, MAI, SnI2 and SnF2 were added to a mixed solution of DMF and DMSO at a molar ratio of x: (1-x): 1: 0.1, and stirred at 70 °C for 2 h to fully dissolve the precursors, thereby preparing a perovskite precursor solution: Step S5: prepare a PDMS solution according to the ratio of PDMS prepolymer to cross-linking agent of 10:1, perform vacuum degassing on the prepared PDMS solution, and then use a rubber-tipped dropper to drop the PDMS solution onto the silicon substrate sample with the nanowire array photolithography; use a coating machine to evenly spin-coat the PDMS solution onto the substrate sample; after spin coating, transfer the sample to a hot plate for heating at 90°C for 3 h; after heating, peel off the PDMS film and put it into a clean container for standby use; Step S6: Place the substrate sample on the operating table in the glove box, and use a pipette to drop 5 μL of the perovskite precursor solution on the surface of the coated substrate sample; then cover the surface of the substrate sample with a PDMS film; then anneal the sample at a temperature of 70 °C and an annealing time of 50 min; after annealing, place the sample in a clean container; cover the container with tin foil with holes; then place the container in the glove box to dry naturally for 10 h; after drying, peel off the PDMS film; Step S7: 50 μL of PMMA solution is dropped onto the manufactured sample, and the PMMA solution is evenly spin-coated into a PMMA film at a set rate using a coating machine, and then the sample is heated and cured at a temperature of 70 °C for 10 min to obtain a laser sample; Step S8: Turn on the femtosecond laser, spectrometer and corresponding test software, place the laser sample on the stage, perform lasing spectrum test after focusing, adjust the power of the pump light through the attenuator to obtain the lasing spectrum under different pumping intensities, then draw the lasing spectrum, and calculate the laser threshold, half-width and quality factor.

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