Resonant cavity variable laser teaching equipment

Abstract

The utility model relates to resonant cavity variable laser teaching equipment, which comprises a laser source, a resonant cavity, a shell and a laser power meter, and is characterized in that the laser source is used for emitting pump light; the resonant cavity comprises a convergence optical system, a laser medium and an output mirror, laser emitted by the laser source is coupled to the end face of the laser medium through the convergence optical system, the laser medium realizes stimulated radiation, absorbs pump light, emits laser and forms laser gain under excitation of the laser, and the high-reflectivity mirror is used for reflecting photons. The output mirror is used for allowing part of photons to escape to form laser output, and the distance between the output mirror and the laser medium is adjustable; the laser power meter is used for measuring the power of laser output, and the convergence optical system is arranged in the shell. The distance between the output mirror and the laser medium is adjustable, so that the length of the resonant cavity is changed, the light emitting power is changed, and students can conveniently know the relation between the length of the resonant cavity and the light emitting power.

Description

Technical Field

[0001] This utility model relates to the field of teaching equipment, and in particular to a teaching device for a resonant cavity variable laser. Background Technology

[0002] Laser teaching equipment is used to explain the principles of lasers. The working principle of a laser is based on the generation of coherent light by excited-state particles through stimulated emission. When pumped by an external light source, particles in the laser medium transition from the ground state to a higher energy state and then transition to a metastable state through a nonradiative process. In the metastable state, the particles have a longer lifetime, which is conducive to the occurrence of stimulated emission.

[0003] The resonant cavity consists of a highly reflective mirror and a partially transparent output coupling mirror (OC mirror). The highly reflective mirror almost completely reflects photons, while the output coupling mirror allows some photons to escape, forming laser output.

[0004] The distance between the high-reflection mirror and the output coupling mirror, which is the length of the resonant cavity, determines the output power of the laser. However, the resonant cavity of current laser teaching equipment is fixed, resulting in a fixed output power. This makes it impossible for students to deduce the relationship between the length of the resonant cavity and the output power, and it cannot adequately meet the requirements of the experimental teaching syllabus for laser principles and technology experimental instruments. Utility Model Content

[0005] In view of this, the present invention provides a teaching device for a resonant cavity variable laser, which makes the length of the resonant cavity adjustable, thereby changing the output power and making it easier for students to understand the relationship between the length of the resonant cavity and the output power.

[0006] The teaching device for a resonant cavity variable laser provided by this utility model adopts the following technical solution:

[0007] A teaching device for a resonant cavity variable laser, comprising:

[0008] A laser source used to emit pump light;

[0009] The resonant cavity includes a converging optical system, a laser medium, and an output mirror. The laser emitted by the laser source is coupled to the end face of the laser medium through the converging optical system. The laser medium achieves stimulated emission under the excitation of the laser, absorbs the pump light and emits laser light to form laser gain. The high-reflectivity mirror is used to reflect photons, and the output mirror is used to allow some photons to escape to form laser output. The distance between the output mirror and the laser medium is adjustable.

[0010] A laser power meter is used to measure the power of a laser output.

[0011] Optionally, the laser medium is a crystal rod, and the end face of the crystal rod is coated with a multilayer dielectric film to achieve high transmittance of pump light wavelength and high reflectivity of laser beam wavelength, thereby realizing effective absorption of pump light and resonant amplification of laser.

[0012] Optionally, the end of the laser rod near the converging optical system is coated with a high-reflection film, and the end near the output mirror is coated with an anti-reflection film.

[0013] Optionally, the output mirror is a concave mirror coated with multiple dielectric films, used to output a laser beam.

[0014] Optionally, the laser source is fiber-coupled end-face pumped.

[0015] Optionally, the converging optical system includes a coupling mirror and a high-reflection mirror, wherein the coupling mirror and the high-reflection mirror are convex lenses, and the high-reflection mirror is disposed on the side closer to the laser medium relative to the coupling mirror.

[0016] Optionally, a track is also included, wherein the output mirror is slidably mounted on the track in a lockable manner for adjusting the distance between the output mirror and the laser medium.

[0017] Optionally, the track is provided with scale lines along its own length.

[0018] Optionally, the system also includes a housing with a transparent top and a hollow interior, and a laser emission port on the side of the housing. The converging optical system and the laser medium are disposed in the hollow portion of the housing.

[0019] Optionally, the housing is an aluminum housing.

[0020] In summary, this utility model includes at least one of the following beneficial technical effects: the distance between the output mirror and the laser medium is adjustable, which changes the length of the resonant cavity and thus changes the output power, making it easier for students to understand the relationship between the length of the resonant cavity and the output power. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of an embodiment of the present utility model;

[0023] Figure 2 This is a schematic diagram of the overall structure of an embodiment of the present utility model;

[0024] Figure 3 This is a cross-sectional view of the housing according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the shell structure of an embodiment of the present utility model.

[0026] Explanation of reference numerals in the attached diagram: 1. Laser; 2. Housing; 3. Laser medium; 4. High-reflection coating; 5. Anti-reflection coating; 6. Output mirror; 7. Laser power meter; 8. Coupler mirror; 9. High-reflection mirror; 10. Track; 11. Scale line. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] The following is in conjunction with the appendix Figure 1-4 The present invention will be described in further detail below.

[0029] This utility model discloses a teaching device for a resonant cavity variable laser.

[0030] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 A teaching device for a resonant cavity variable laser includes a laser source, a resonant cavity, a housing 2, and a laser power meter 7. The laser source emits pump light. The resonant cavity includes a converging optical system, a laser medium 3, and an output mirror 6. The laser emitted by the laser source is coupled to the end face of the laser medium 3 through the converging optical system. Under the excitation of the laser, the laser medium 3 achieves stimulated emission, absorbing the pump light and emitting laser light, forming laser gain. A high-reflectivity mirror 9 is used to reflect photons, and the output mirror 6 is used to allow some photons to escape to form laser output. The distance between the output mirror 6 and the laser medium 3 is adjustable. The laser power meter 7 is used to measure the power of the laser output. The converging optical system is set in the housing 2. The adjustable distance between the output mirror 6 and the laser medium 3 changes the length of the resonant cavity, thereby changing the output power, making it easier for students to understand the relationship between the length of the resonant cavity and the output power.

[0031] In this embodiment, the laser source, resonant cavity, and laser power meter 7 are mounted on a platform. The platform is used to install and fix all optical components and related equipment, providing a flat and stable surface to reduce the impact of vibration and external interference on optical alignment, thereby ensuring the accuracy and reliability of the experiment.

[0032] The laser source includes a pump source and a constant current source. The pump source is fiber-coupled end-face pumped, and an fiber-optic output semiconductor laser 1 is selected as the pump source. The pump source is used to excite the laser gain medium, providing sufficient energy to cause atoms or molecules in the gain medium to transition to excited states, thereby generating stimulated emission. The beam emitted by the laser diode is coupled into the optical fiber, and the fiber transmission reduces the divergence angle of the output beam and enhances the circular symmetry of the output beam. This pumping method reduces the requirements for device adjustment, thereby increasing the possibility of mass production.

[0033] The pump source is mounted on an optical platform to ensure that the pump beam is aligned with the YVO4 crystal.

[0034] Connect the pump source and the constant current source to ensure a stable current output from the pump source. Determine the output current parameters of the constant current source to provide stable pump power.

[0035] It also includes laser 1, which uses He-Ne laser 1 as a reference light source to provide a stable visible beam for optical alignment. He-Ne laser 1 serves as an alignment light source for initial adjustment of the optical cavity alignment. He-Ne laser 1 is mounted on an optical platform, ensuring that its beam coincides with the optical axis within the laser 1 cavity.

[0036] Laser power meter 7 measures the laser output power. By monitoring the output power, the performance and efficiency of laser 1 can be evaluated, and parameters such as pump power and cavity length can be adjusted to optimize the output. Laser power meter 7 is placed at the output end of the semi-reflective mirror to measure the laser output power.

[0037] The working principle of a laser source is based on the generation of coherent light by excited-state particles through stimulated emission. When pumped by an external light source, particles in the laser medium 3 transition from the ground state to a higher energy state and then transition to a metastable state through a nonradiative process. In the metastable state, the particles have a longer lifetime, which is conducive to stimulated emission. The light reflects back and forth within the resonant cavity. Each time it passes through the medium, the metastable active ions undergo stimulated emission with the incident photon, generating a new photon with the same frequency, phase, and polarization as the incident photon. This process increases the number of photons in the cavity, creating gain.

[0038] The resonant cavity consists of a highly reflective mirror 9 and a partially transparent coupling mirror 8 (OC mirror). The highly reflective mirror 9 almost completely reflects photons, while the output coupling mirror 8 allows some photons to escape, forming laser output. When the photon generation rate in the gain medium exceeds the loss rate, some photons are output through the OC mirror, forming a stable laser beam. The remaining photons continue to circulate within the cavity, maintaining laser oscillation. The threshold condition for laser operation is expressed as follows:

[0039]

[0040] Where l is the length of the gain medium and R is the reflectivity of the resonant cavity mirror.

[0041] Considering the input power, the reflectivity of the resonant cavity, and the gain and loss of the medium, the laser output power can be calculated as follows:

[0042] P out =P in (1-R)e (g·l-αl) #(16)

[0043] Among them, P in α represents the input power of the pump light, and α represents the loss coefficient per unit length.

[0044] Laser medium 3 is a crystal rod with multiple dielectric films coated on its end faces. This allows for high transmittance of the pump light wavelength while providing high reflectivity of the laser beam wavelength, thereby achieving effective absorption of the pump light and resonant amplification of the laser. The crystal is a YVO4 crystal, which has high absorption and emission efficiency. It can achieve stimulated emission under the excitation of the pump source, absorbing the pump light and emitting laser light to form laser gain.

[0045] The end of the laser rod near the converging optical system is coated with a high-reflection film 4, and the end near the output mirror 6 is coated with an anti-reflection film 5.

[0046] A high-reflectivity film 4 is coated on the end of the laser rod closest to the converging optical system. Based on the multi-beam interference effect, the reflectivity of the optical surface of the element is improved by selecting a film material with a refractive index higher than that of the substrate. The high-reflectivity film 4 ensures that the pump light is efficiently coupled into the crystal rod and highly reflects the generated laser beam, thereby enhancing the oscillation and amplification of the laser in the resonant cavity.

[0047] An antireflection coating 5 is coated on the end of the laser rod closest to the output mirror 6. The antireflection coating 5 is designed to minimize surface reflection from the substrate to achieve maximum transmittance. This helps reduce laser loss during the output process and improves the laser's output efficiency and power.

[0048] The converging optical system includes a coupling mirror 8 and a high-reflection mirror 9, both of which are convex lenses. The high-reflection mirror 9 is positioned on the side closer to the laser medium 3 relative to the coupling mirror 8.

[0049] The function of the coupling mirror 8 is to achieve effective injection and coupling of pump light, and to ensure effective interaction between pump light and signal light. The coupling mirror 8 utilizes the different wavelengths of pump light and oscillation light to achieve specific transmittance and reflectance, thereby optimizing the pumping effect.

[0050] The high-reflectivity mirror 9 reflects light of a specific wavelength, ensuring that the light can oscillate and be amplified effectively within the resonant cavity.

[0051] A multilayer dielectric film is coated on the left end face of the laser rod, which has high transmittance for the corresponding wavelength of the pump light and high reflectivity for the corresponding wavelength of the generated laser beam, thereby improving the output efficiency and power of the laser.

[0052] The coupling mirror 8 and the high-reflection mirror 9 in the converging optical system work together to generate and amplify the laser, ensuring the stable operation and efficient output of the laser 1.

[0053] Output mirror 6 is a concave mirror coated with multiple dielectric films, used to output the laser beam. The purpose of the coating is to change the reflection and transmission characteristics of the material surface to meet the transmittance requirements of output mirror 6 for different applications. The multilayer dielectric film is selected according to the laser source. In this embodiment, antireflection film 5 is selected. Utilizing the principle of light interference, one or more transparent dielectric films are coated on the surface of the optical element to reduce reflection loss and increase transmitted light intensity, which can significantly improve the light transmission performance of the optical system and make the image more vivid and clear.

[0054] It also includes a track 10 set on the platform, and an output mirror 6 is slidably mounted on the track 10 in a lockable manner to adjust the distance between the output mirror 6 and the laser medium 3. The output mirror 6 is provided with a slider, which is slidably mounted on the track 10. The slider is provided with a locking member formed by bolts, and the locking member is locked by abutting against the track 10.

[0055] The track 10 has scale lines 11 along its length to improve adjustment accuracy. By setting the track 10, the output mirror 6 can be precisely adjusted to ensure that its position and other parameters meet the requirements, thereby improving the output effect and performance of the laser 1.

[0056] The adjustment method can also be electric adjustment, using electric cylinders, screw motors, etc.

[0057] The light waves inside the laser resonant cavity form a stable standing wave mode, thereby generating laser output. The length of the resonant cavity determines the wavelength of the oscillation mode in laser 1, so the laser wavelength of laser 1 can be tuned by changing the length of the resonant cavity.

[0058] It also includes a housing 2, which is transparent at the top and hollow inside. The side of the housing 2 has a laser emission port. The converging optical system and the laser medium 3 are disposed in the hollow part of the housing 2. The housing 2 is made of aluminum and has an opening at the top. The top of the housing 2 is provided with a transparent plate, which can be a glass plate or an acrylic plate. The transparency allows students to observe the structure of the converging optical system, which is convenient for teaching.

[0059] The experimental steps are as follows:

[0060] 1. Cavity alignment

[0061] Start the He-Ne laser 1 and align its beam with the optical cavity of laser 1. Adjust the angles of the total reflection mirror and the half reflection mirror to make the He-Ne laser beam undergo multiple reflections within the cavity and be perfectly aligned with the optical axis. By adjusting the positions of the cavity mirror and the YVO4 crystal, ensure that the cavity length is within the appropriate range to achieve optimal laser resonance.

[0062] 2. Laser Pumping and Laser Output Measurement

[0063] Start the pump source and gradually increase the pump power until the YVO4 crystal begins to produce laser output. Use a laser power meter 7 to measure the laser power at the output end and record the laser output power at different pump powers. Adjust the cavity length, move the cavity mirror via a slide rail, and record the relationship between the laser output power and the cavity length.

[0064] 3. Cavity length adjustment and frequency tuning

[0065] While keeping the pump power constant, the resonant cavity length was finely adjusted via track 10, and the effect of the resonant cavity length change on the laser output frequency was recorded.

[0066] 4. Experimental Data Recording and Analysis

[0067] Record the output laser power, frequency, and other parameters under different cavity lengths, pump powers, and laser modes. Analyze the experimental data and plot the relationship between laser output power and cavity length and pump power to verify the consistency between the performance of laser 1 and the theoretical model.

[0068] 5. Shut down the system

[0069] Gradually reduce the pump source current, shut down the constant current source, and turn off the He-Ne laser 1 and laser power meter 7. After ensuring the safe shutdown of all equipment, organize and summarize the experimental data. Specific examples are used in this paper to illustrate the principle and implementation of this invention. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this invention.

[0070] The above description is only a preferred embodiment of this utility model. It should be noted that due to the limitations of written expression, there are objectively infinite specific structures. For those skilled in the art, several improvements, modifications, or changes can be made without departing from the principle of this utility model, and the above technical features can be combined in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the concept and technical solution of the utility model to other occasions without modification, should all be considered within the protection scope of this utility model.

Claims

1. A teaching device for a resonant cavity variable laser, characterized in that: include: A laser source used to emit pump light; The resonant cavity includes a converging optical system, a laser medium, and an output mirror. The laser emitted by the laser source is coupled to the end face of the laser medium through the converging optical system. The laser medium achieves stimulated emission under the excitation of the laser, absorbs the pump light and emits laser light to form laser gain. It also includes a high-reflection mirror for reflecting photons. The output mirror allows some photons to escape to form laser output. The distance between the output mirror and the laser medium is adjustable. A laser power meter is used to measure the power of a laser output.

2. The resonant cavity variable laser teaching device according to claim 1, characterized in that: The laser medium is a crystal rod, and the end face of the crystal rod is coated with a multilayer dielectric film to achieve high transmittance of pump light wavelength and high reflectivity of laser beam wavelength, thereby realizing effective absorption of pump light and resonant amplification of laser.

3. The resonant cavity variable laser teaching device according to claim 2, characterized in that: The end of the crystal rod near the converging optical system is coated with a high-reflection film, and the end near the output mirror is coated with an anti-reflection film.

4. The resonant cavity variable laser teaching device according to claim 1, characterized in that: The output mirror is a concave mirror coated with multiple dielectric films, used to output a laser beam.

5. The resonant cavity variable laser teaching device according to claim 1, characterized in that: The laser source is fiber-coupled end-face pumped.

6. The resonant cavity variable laser teaching device according to claim 2, characterized in that: The converging optical system includes a coupling mirror and a high-reflection mirror, both of which are convex lenses. The high-reflection mirror is positioned relative to the coupling mirror on the side closer to the laser medium.

7. The resonant cavity variable laser teaching device according to claim 1, characterized in that: It also includes a track, in which the output mirror is slidably mounted in a lockable manner to adjust the distance between the output mirror and the laser medium.

8. The resonant cavity variable laser teaching device according to claim 7, characterized in that: The track has graduations along its length.

9. The resonant cavity variable laser teaching device according to claim 1 or 6, characterized in that: It also includes a housing, the top of which is transparent and the interior is hollow, and the side of the housing has a laser emission port, and the converging optical system and the laser medium are disposed in the hollow part of the housing.

10. The resonant cavity variable laser teaching device according to claim 9, characterized in that: The casing is made of aluminum.

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