A method for dynamically regulating laser mode based on thermo-optic effect

Abstract

The application discloses a kind of based on thermo-optic effect dynamic regulation and control laser mode method, comprising the following steps: gallium-doped zinc oxide microrod is placed on insulating substrate, electrode is prepared at both ends;Pump light source is focused on zinc oxide microrod and is excited by light, and the light signal of gallium-doped zinc oxide microrod is collected;Voltage is applied to gallium-doped zinc oxide microrod using direct current power supply, and injected current is observed;While carrying out optical pumping, and real-time collection of light signal after energizing, comparative analysis of optical spectrum signal before and after energizing.The application utilizes the Joule heat generated when electricity is injected, to realize the dynamic regulation and control of laser mode of ZnO microcavity.Compared with traditional environmental control mode, electricity injection mode is more flexible, heating is faster, and has the characteristics of high precision and the like.This electronic temperature control mode lays a solid foundation for the practicability and integration of tunable laser.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic technology and relates to a method for dynamically controlling laser modes based on thermo-optical effects. Background Technology

[0002] Lasers, a great invention of the 20th century, have had a profound impact on defense, manufacturing, communications, and life sciences since their inception. The development of laser technology has therefore attracted widespread attention from researchers worldwide, especially the design and construction of novel lasers with dynamically tunable wavelengths. Currently, methods for controlling laser wavelength include distributed feedback, distributed Bragg reflection, self-absorption, and bandgap engineering. However, these methods can only be pre-designed; once fixed, the emitted laser wavelength is also fixed, and dynamic reversible control of the wavelength is not possible. In recent years, patent applicants have achieved dynamic control of zinc oxide whispering-gallery mode lasers by changing the refractive index of micrometer rods through external mechanical strain. However, strain loading seems to only work in specific systems (such as microelectromechanical systems, nanoelectromechanical systems, etc.), and may be difficult to implement for optical integration. Therefore, there is an urgent need to develop a new control method that is easy for photonic integration. Summary of the Invention

[0003] The purpose of this invention is to provide a method for dynamically controlling laser modes based on the thermo-optic effect. This method utilizes Joule heating generated by electrical injection to change the refractive index of gallium-doped zinc oxide microrods, thereby achieving the purpose of dynamic control of cavity modes.

[0004] Technical solution: The present invention provides a method for dynamically controlling laser modes based on thermo-optical effects, comprising the following steps:

[0005] (1) A gallium-doped zinc oxide microrod is placed on an insulating substrate, and electrodes are prepared at both ends;

[0006] (2) Focus the pump light source onto the gallium-doped zinc oxide microrod for photoexcitation and collect the optical signal from the gallium-doped zinc oxide microrod;

[0007] (3) Apply a voltage to a gallium-doped zinc oxide microrod using a DC power supply and observe the injection current;

[0008] (4) Simultaneously perform optical pumping and collect the optical signal after power-on in real time, and compare and analyze the spectral signals before and after power-on.

[0009] Furthermore, in step (1), the gallium doping content in the zinc oxide microrod is 0% to 10%, the length is 0.1 to 1.5 cm, and the diameter is 1 to 20 μm;

[0010] Furthermore, in step (1), the insulating substrate material includes silicon dioxide, quartz sheet, glass slide, sapphire or mica, with a length of 1 to 5 cm, a width of 0.5 to 2 cm, and a thickness of 100 to 1000 μm.

[0011] Furthermore, in step (1), the electrode material is metallic silver or indium, and the distance between the two electrodes is 100 to 2000 μm.

[0012] Furthermore, since the lasing mode has an extremely narrow half-width at half-maximum (WHM), it places certain requirements on the resolution of the spectrometer. If the resolution is too low, it cannot be collected. Therefore, the excitation source should preferably be a light source with a pulse width of less than nanoseconds. Thus, in step (2), the repetition frequency of the pump light source is 1–6000 Hz, the pulse width is 50 fs–50 ns, and the wavelength is set to 315–360 nm; the resolution of the spectrometer for collecting the lasing signal is 0.03–0.3 nm, and the grating lines are 300–1200 g / mm.

[0013] Furthermore, in step (2), the sample is placed on a three-dimensional adjustable platform of a micro-area system equipped with an optical microscope, and the pump light is focused onto the sample by adjustment.

[0014] Furthermore, the adjustment accuracy of the three-dimensional adjustable platform is 1–10 μm, and the stroke is 3–8 cm.

[0015] Furthermore, the objective lens of the optical microscope has a magnification of 10 to 50 times, and the eyepiece magnification has a magnification of 10 to 20 times.

[0016] Furthermore, in step (3), the DC power supply voltage is applied in the range of 0 to 210V, and the adjustment accuracy is 0.1 to 1V.

[0017] Beneficial effects:

[0018] (1) Compared with the prior art, the control method of the present invention has the characteristics of being dynamic, real-time and reversible;

[0019] (2) The present invention is based on the thermo-optical effect to dynamically control the zinc oxide whispering gallery mode, which has higher control precision;

[0020] (3) The present invention is based on the method of generating Joule heat by electrical injection for dynamic control, which makes it easier to integrate with subsequent photonic circuits;

[0021] (4) This invention utilizes the thermo-optic effect to extend the current modulation based on traditional silicon resonators, located in the near-infrared band (~1550nm), to the ultraviolet band (~390nm) of zinc oxide microcavities. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the device structure.

[0023] Figure 2 These are lasing spectra under different bias voltages.

[0024] Figure 3 This is a graph showing the relationship between injected electrical power and the change in cavity mode resonant wavelength.

[0025] Figure 4 This is the temperature distribution of a gallium-doped zinc oxide microrod under a 0V bias voltage.

[0026] Figure 5 This is the temperature distribution of a gallium-doped zinc oxide microrod under a 5V bias voltage. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0028] like Figure 1 The diagram shows the device structure, which mainly includes gallium-doped zinc oxide microrods, metal electrodes, and an insulating substrate.

[0029] This invention provides a method for dynamically controlling laser modes based on thermo-optical effects. By injecting electricity, gallium-doped zinc oxide microrods generate Joule heating, thereby changing their refractive index and achieving dynamic, real-time, and reversible control of optical cavity modes.

[0030] Invention Principle: Optical cavity modes are closely related to the gain medium, microcavity size, and refractive index. Wavelength-tunable lasers based on the former two lack dynamic, real-time, and reversible control characteristics. Starting from the principles of physics, introducing a physical field to change the refractive index of gallium-doped zinc oxide microrods is an effective way to achieve the above objectives.

[0031] The present invention provides a method for dynamically controlling laser modes based on thermo-optical effects, comprising the following steps:

[0032] (1) A gallium-doped zinc oxide microrod is placed on an insulating substrate, and electrodes are fabricated at both ends. The gallium doping content of the zinc oxide microrod is 0% to 10%, the length is 0.1 to 1.5 cm, and the diameter is 1 to 20 μm. The insulating substrate material includes silicon dioxide, quartz sheet, glass slide, sapphire, or mica, with a length of 1 to 5 cm, a width of 0.5 to 2 cm, and a thickness of 100 to 1000 μm. The electrode material is metallic silver or indium, and the distance between the two electrodes is 100 to 2000 μm.

[0033] (2) Place the sample on the three-dimensional adjustable platform of the micro-area system equipped with an optical microscope, and focus the pump light onto the gallium-doped zinc oxide microrod for photoexcitation by adjustment, and collect the light signal of the gallium-doped zinc oxide microrod; the adjustment accuracy of the three-dimensional micro-area platform is 1-10 μm, and the travel is 3-8 cm; the objective lens magnification of the optical microscope is 10-50 times, and the eyepiece magnification is 10-20 times.

[0034] Because the lasing mode has an extremely narrow half-width at half-maximum (HWHM), it requires a certain resolution from the spectrometer. If the resolution is too low, it cannot be collected. Therefore, the excitation source should preferably be a light source with a pulse width of less than nanoseconds. Thus, in step (2), the repetition frequency of the pump light source is 1–6000 Hz, the pulse width is 50 fs–50 ns, and the wavelength is set to 315–360 nm; the resolution of the spectrometer for collecting the lasing signal is 0.03–0.3 nm, and the grating lines are 300–1200 g / mm.

[0035] (3) Apply voltage to gallium-doped zinc oxide microrods using a DC power supply and observe the injection current; the DC power supply voltage range is 0 to 210V, and the adjustment accuracy is 0.1 to 1V.

[0036] (4) Simultaneously perform optical pumping and collect the optical signal after power-on in real time. Compare and analyze the spectral signals before and after power-on to obtain the relationship between the applied bias voltage and the change of the same cavity mode.

[0037] The gallium-doped zinc oxide microrods used in this invention can be obtained commercially or synthesized in-house. The specific preparation method of the gallium-doped zinc oxide microrods includes the following steps:

[0038] S1. Weigh zinc oxide powder, graphite powder and gallium oxide powder in a mass ratio of 1:1:0~0.5, mix them and grind them thoroughly. Use the ground mixture as the reaction source.

[0039] S2. Clean and dry the silicon wafer to serve as a substrate, and place the polished surface, as the growth surface, onto the quartz boat containing the reaction source without contacting the reaction source.

[0040] S3. The quartz boat containing the reaction source and the silicon substrate is placed into a quartz tube with openings at both ends, and the whole thing is placed in the high-temperature zone of the tube furnace for reaction at a temperature of 1100-1200℃.

[0041] S4. Argon and oxygen are introduced into the tube furnace until the reaction is complete, and gallium-doped zinc oxide microrod arrays are obtained on the silicon wafer. After cooling to room temperature, they are removed.

[0042] Example 1:

[0043] The method for dynamically controlling the laser mode based on the thermo-optical effect in this embodiment includes the following steps:

[0044] (1) Select a single zinc oxide microrod with a gallium doping content of 0.2% and a length of 0.5cm and a diameter of 10μm and place it on an insulating silicon dioxide substrate with a length and width of 1cm×1cm; press indium particles at both ends of the microrod as electrodes and the electrode spacing is 500μm;

[0045] (2) The prepared device was placed on a three-dimensional displacement stage with an accuracy of 1 μm and a progress of 5 cm. The displacement stage was adjusted, and the pump light with an excitation wavelength of 325 nm, a repetition frequency of 1000 Hz, and a pulse width of 100 fs was focused onto the gallium-doped zinc oxide microrod through an optical microscope with an objective lens of 10 magnification and an eyepiece of 10 magnification. The optical signal of the zinc oxide was collected by a spectrometer with a spectral resolution of 0.03 nm and a grating line of 1200 g / mm.

[0046] (3) Apply a continuous bias voltage to the device using a DC power supply, with a range of 0 to 4.5V and an adjustment accuracy of 0.1V;

[0047] (4) Simultaneously acquire the spectral signal with continuously applied bias voltage and observe the changes in the spectrum.

[0048] like Figure 2 As shown, with the increase of the applied bias voltage, the lasing mode shifts towards longer wavelengths; finally, the relationship between the injection power and the cavity mode shift can be obtained, as shown in the figure. Figure 3 As shown. Figure 4 and Figure 5 This provides direct evidence that electrical injection generates Joule heating.

[0049] Example 2:

[0050] The method for dynamically controlling the laser mode based on the thermo-optical effect in this embodiment includes the following steps:

[0051] (1) Select a single zinc oxide microrod with a gallium doping content of 0.2% and a length of 0.8cm and a diameter of 5μm and place it on an insulating silicon dioxide substrate with a length and width of 1cm×1cm; press indium particles at both ends of the microrod as electrodes and the electrode spacing is 600μm;

[0052] (2) The prepared device was placed on a three-dimensional displacement stage with an accuracy of 2μm and a depth of 3cm. The displacement stage was adjusted, and the pump light with an excitation wavelength of 355nm, a repetition frequency of 2000Hz, and a pulse width of 100fs was focused onto the gallium-doped zinc oxide microrod through an optical microscope with an objective lens of 10x and an eyepiece of 10x. The optical signal of the zinc oxide was collected by a spectrometer with a spectral resolution of 0.03nm and a grating line of 1200g / mm.

[0053] (3) Apply a continuous bias voltage to the device using a DC power supply, with a range of 0 to 10V and an adjustment accuracy of 0.1V;

[0054] (4) Simultaneously acquire the spectral signal with continuously applied bias voltage and observe the changes in the spectrum.

[0055] Example 3:

[0056] The method for dynamically controlling the laser mode based on the thermo-optical effect in this embodiment includes the following steps:

[0057] (1) Select a single zinc oxide microrod with a gallium doping content of 0.2% and a length of 1.0 cm and a diameter of 3 μm and place it on an insulating silicon dioxide substrate with a length and width of 1 cm × 1 cm; press indium particles at both ends of the microrod as electrodes and the electrode spacing is 800 μm;

[0058] (2) The prepared device was placed on a three-dimensional displacement stage with an accuracy of 1 μm and a progress of 8 cm. The displacement stage was adjusted, and the pump light with an excitation wavelength of 325 nm, a repetition frequency of 6000 Hz, and a pulse width of 100 fs was focused onto the gallium-doped zinc oxide microrod through an optical microscope with an objective lens of 10 magnification and an eyepiece of 10 magnification. The optical signal of zinc oxide was collected by a spectrometer with a spectral resolution of 0.03 nm and a grating line of 1200 g / mm.

[0059] (3) Apply a continuous bias voltage to the device using a DC power supply, with a range of 0 to 50V and an adjustment accuracy of 0.1V;

[0060] (4) Simultaneously acquire the spectral signal with continuously applied bias voltage and observe the changes in the spectrum.

[0061] Example 4:

[0062] The method for dynamically controlling the laser mode based on the thermo-optical effect in this embodiment includes the following steps:

[0063] (1) Select a single zinc oxide microrod with a gallium doping content of 0.2% and a length of 0.5cm and a diameter of 5μm and place it on an insulating silicon dioxide substrate with a length and width of 1cm×1cm; press indium particles at both ends of the microrod as electrodes and the electrode spacing is 1000μm;

[0064] (2) The prepared device was placed on a three-dimensional displacement stage with an accuracy of 1 μm and a progress of 5 cm. The displacement stage was adjusted, and the pump light with an excitation wavelength of 355 nm, a repetition frequency of 3000 Hz, and a pulse width of 190 fs was focused onto the gallium-doped zinc oxide microrod through an optical microscope with an objective lens of 10 magnification and an eyepiece of 10 magnification. The optical signal of the zinc oxide was collected by a spectrometer with a spectral resolution of 0.03 nm and a grating line of 1200 g / mm.

[0065] (3) Apply a continuous bias voltage to the device using a DC power supply, with a range of 0 to 20V and an adjustment accuracy of 0.1V;

[0066] (4) Simultaneously acquire the spectral signal with continuously applied bias voltage and observe the changes in the spectrum.

[0067] Comparative example:

[0068] This comparative example is basically the same as Example 1, except that the gallium doping content is 0.5%.

[0069] The prepared device was dynamically modulated according to the method in Example 1. Due to the different gallium doping content, different voltages were required to achieve the modulation purpose.

Claims

1. A method for dynamically controlling laser modes based on thermo-optical effects, characterized in that, The refractive index of gallium-doped zinc oxide microrods is altered by electro-injection, resulting in Joule heating. This process includes the following steps: (1) A gallium-doped zinc oxide microrod is placed on an insulating substrate, and electrodes are fabricated at both ends; (2) Focus the pump light source onto the gallium-doped zinc oxide microrod for photoexcitation and collect the optical signal from the gallium-doped zinc oxide microrod; (3) Apply a voltage to a gallium-doped zinc oxide microrod using a DC power supply and observe the injection current; (4) Simultaneously perform optical pumping and collect the optical signal after power-on in real time, and compare and analyze the spectral signals before and after power-on.

2. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 1, characterized in that: In step (1), the gallium doping content of the zinc oxide microrod is 0%~10%, the length is 0.1~1.5 cm, and the diameter is 1~20 μm.

3. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 1, characterized in that: In step (1), the insulating substrate material includes silicon dioxide, sapphire or mica, with a length of 1~5cm, a width of 0.5~2cm, and a thickness of 100~1000μm.

4. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 1, characterized in that: In step (1), the electrode material is metallic silver or indium, and the distance between the two electrodes is 100~2000μm.

5. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 1, characterized in that: In step (2), the repetition frequency of the pump light source is 1~6000Hz, the pulse width is 50 fs~50 ns, and the wavelength is set to 315~360nm; the resolution of the spectrometer for collecting the lasing signal is 0.03~0.3 nm, and the grating lines are 300~1200g / mm.

6. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 1, characterized in that: In step (2), gallium-doped zinc oxide microrods are placed on a three-dimensional adjustable platform of a micro-area system equipped with an optical microscope, and the pump light is focused onto the gallium-doped zinc oxide microrods by adjustment.

7. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 6, characterized in that: The objective lens of the optical microscope has a magnification of 10 to 50 times, and the eyepiece magnification is 10 to 20 times.

8. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 6, characterized in that: The adjustment accuracy of the three-dimensional adjustable platform is 1~10 μm, and the stroke is 3~8 cm.

9. The method for dynamically controlling laser modes based on thermo-optical effects according to claim 1, characterized in that: In step (3), the DC power supply voltage is applied in the range of 0~210V, and the adjustment accuracy is 0.1~1V.

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