Mode regulation and control laser based on Feshbach-like resonance

Abstract

The invention discloses a mode regulation and control laser based on Feshbach-like resonance, and belongs to the technical field of laser. Comprising a multimode gain module, a saturable absorption module, a Feshbach resonance tuning module and an output module which are sequentially arranged along an optical path. The multimode gain module provides optical signal energy and generates a multimode optical field; the saturable absorption module forms a pulse signal; the Feshbach resonance tuning module adjusts the polarization state through a polarization control part, changes the reflectivity of different frequency components by using a frequency reflectivity curve tuning device, constructs a mode coupling channel and introduces similar Feshbach resonance; and the output module is used for exporting the regulated and controlled laser signal. The directional distribution of the gain among different modes is realized through Feshbach-like resonance, the output light field mode is regulated and controlled from the perspective of active gain design, the energy loss in the traditional light field modulation is avoided, the energy utilization rate is obviously improved, and the method is particularly suitable for high-power and multi-mode dynamic switching scenes, and can be applied to the fields of hyperfine processing, high-speed communication and the like.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a mode-controlled laser based on a Feshbach-like resonance. Background Technology

[0002] Mode modulation is a key technique for optimizing optical field characteristics in laser technology and is of great significance to laser applications. On the one hand, precise control of mode distribution can suppress interference from higher-order modes, improve beam quality, and concentrate laser energy with a smaller divergence angle, meeting the requirements of high-precision scenarios such as ultra-fine laser processing. On the other hand, mode modulation can generate special optical fields such as vortex beams, and utilize their unique spiral phase to expand application boundaries. For example, it can enable multiplexing of multiplexed signals to increase communication transmission capacity, providing the possibility for breaking through bandwidth bottlenecks in 5G and future high-speed communications.

[0003] Existing mode modulation techniques are categorized into two types based on their location: external cavity modulation and internal cavity modulation. Widely used techniques often utilize devices such as spatial light modulators to directly intervene in the optical field. The core advantage of this approach lies in its "direct controllability" of the optical field distribution, i.e., precisely reshaping the wavefront structure of the optical field by loading specific phase and amplitude modulation patterns. However, this "direct control" characteristic also leads to significant drawbacks: its essence is the "screening and modification" of the original optical field. Unselected optical field components (such as higher-order modes and non-target phase components) are lost due to diffraction and absorption effects during modulation, resulting in a significant reduction in energy utilization and making it difficult to meet the demands of high-power, multi-mode dynamic switching scenarios. Summary of the Invention

[0004] To address the problem of low energy utilization caused by the "screening and modification" of the optical field during mode modulation in existing technologies, this invention provides a mode-modulated laser based on a Feshbach-like resonance. By constructing an inter-mode coupling channel through an intracavity structure, a Feshbach-like resonance is introduced to achieve directional distribution of gain among different modes, thereby realizing mode modulation from the perspective of active gain design and improving energy utilization.

[0005] To achieve the above objectives, the present invention provides a mode-controlled laser based on a Feshbach-like resonance, comprising a multimode gain module, a saturable absorption module, a Feshbach resonance tuning module, and an output module arranged sequentially along the optical path; The multimode gain module is used to provide optical signal energy and generate a multimode optical field; the saturable absorption module is used to form a pulse signal. The Feshbach resonance tuning module works in coordination with the multimode gain module to construct coupling channels between modes and introduce Feshbach-like resonance to achieve directional distribution of gain between different modes. The output module is used to output the modulated laser signal; the Feshbach resonance tuning module makes the gain curves of different frequencies resonate with the mode gain curves of the multimode gain module, thereby realizing the control of the mode distribution of the laser output light field.

[0006] Preferably, the multimode gain module serves as the laser's optical signal energy source, comprising a pump source, a first collimator, a first reflector, a dichroic mirror, a second collimator, and a multimode gain medium. The pump source provides the energy required by the resonant cavity; the first collimator collimates the beam emitted from the pump source; the first reflector adjusts the direction of the collimated pump beam; the dichroic mirror combines the signal beam and the pump beam within the resonant cavity; the second collimator guides the combined beam into the multimode gain medium; and the interaction between the signal beam and the pump beam in the multimode gain medium generates a multimode optical field.

[0007] Preferably, the saturable absorption module provides a saturable absorption effect for the formation of pulse signals, and can be composed of a saturable absorber or an artificial saturable absorber, used to shape continuous light into pulsed light signals.

[0008] Preferably, the Feshbach resonant tuning module includes a polarization control section and a frequency reflectivity curve tuning device; the polarization control section is used to adjust the polarization state of the signal light in the resonant cavity; the frequency reflectivity curve tuning device is used to tune the reflectivity of different frequency components of the signal light in the resonant cavity to affect the gain curve of different frequency components.

[0009] Preferably, the polarization control section includes a quarter-wave plate and a half-wave plate, which are sequentially arranged in the optical path to coordinately adjust the polarization state of the signal light.

[0010] Preferably, the frequency reflectivity curve tuning device is a position-adjustable reflector, which adjusts the reflectivity of different frequency components by changing the cavity length of the resonant cavity. This, in turn, affects the gain curves of different frequency components. When the gain curves of different frequencies satisfy the resonance relationship with the gain curve of the multimode gain medium mode, a Feshbach-like resonance is formed, achieving tuning of the signal light mode proportion.

[0011] Preferably, the saturable absorber can be replaced with any component that has a saturable absorption effect.

[0012] Preferably, the frequency reflectivity curve tuning device can be replaced with any component that can change the frequency reflectivity curve of the resonant cavity.

[0013] Preferably, the formation condition of Feshbach-like resonance is: the frequency gain curve after tuning by the frequency reflectivity curve tuning device and the mode gain curve of the multimode gain medium satisfy the resonance relationship. At this time, the modes in the multimode gain medium form a resonance pair, realizing the directional distribution of gain between modes.

[0014] Preferably, the output module includes a second reflector and a beam splitter; the second reflector is used to adjust the propagation direction of the signal light, and the beam splitter outputs the signal light in the resonant cavity as the output laser according to a preset ratio.

[0015] The working principle of this invention is as follows: the pump light provided by the pump source is collimated by the first collimator, its direction is adjusted by the first reflecting mirror, and then it is introduced into the multimode gain medium through the dichroic mirror; the signal light is generated in the multimode gain medium and shaped into pulse light by the saturable absorption module; after the polarization state of the pulse light is adjusted by the quarter-wave plate and the half-wave plate, the reflectivity of different frequency components is changed by the frequency reflectivity curve tuning device; when the frequency gain curve tuned by the frequency reflectivity curve tuning device and the mode gain curve of the multimode gain medium satisfy the resonance relationship, a Feshbach-like resonance is formed, realizing the directional distribution of gain between modes, thereby tuning the mode ratio of the signal light; finally, the modulated signal light is output through the output module.

[0016] From a quantum mechanical perspective, the two modes of a multimode gain medium can be viewed as two energy levels of a two-level system, i.e., states. Harmony (in, LP For linear polarization (LinearPolarization).

[0017] The Hamiltonian of the two-level system is: ; in, is the number quantum of photons, representing the number energy level of photons in the light field, and is a fundamental variable in quantum mechanical models. ω is the angular frequency, representing the oscillation frequency of the light field. Energy level detuning represents the energy level difference within a two-level system and is related to the mode gain curve. The mode coupling constant is defined by a formula and represents the coupling strength between modes.

[0018] The mode coupling constant can be derived from the eigenstates of the Hamiltonian. The expression: ; in, This is due to frequency detuning. Mode selection can be achieved by adjusting the Feshbach resonance tuning module to make the frequency reflectivity curve of the resonant cavity couple with the mode. is an angular parameter representing the polarization direction angle of the light field. This refers to the saturation frequency or the signal frequency. This is the reference frequency or the fundamental frequency of the resonant cavity.

[0019] Therefore, the present invention provides a mode-controlled laser based on a Feshbach-like resonance using the above-described structure, which has the following beneficial effects: (1) This invention introduces Feshbach-like resonance through a resonant cavity to achieve directional distribution of gain between different modes, realizes mode control from the perspective of active gain design, avoids energy loss caused by "screening and modifying" the optical field in the prior art, and significantly improves energy utilization.

[0020] (2) The present invention can flexibly adjust the mode ratio through the Feshbach resonance tuning module, which is especially suitable for high power and multi-mode dynamic switching scenarios, thus expanding the application range of lasers.

[0021] (3) The modules in this invention are reasonably designed and key components are replaceable, which reduces the difficulty of equipment debugging and maintenance and has strong practicality.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the module structure of the present invention; Figure 2 This is a schematic diagram of the specific structure of the present invention; Figure 3 A graph showing the reflectivity curve of a frequency reflectivity curve tuning device; Figure 4 A diagram showing the proportion of modes tuned to Feshbach resonance. Figure Labels 1-Pump source, 2-First collimator, 3-First reflector, 4-Dichroic mirror, 5-Second collimator, 6-Multimode gain medium, 7-Saturable absorber, 8-1 / 4 wave plate, 9-1 / 2 wave plate, 10-Frequency reflectivity curve tuning device, 11-Second reflector, 12-Optical beam splitter. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0026] Example like Figure 1 As shown, the present invention provides a mode-controlled laser based on a Feshbach-like resonance, including a multimode gain module, a saturable absorption module, a Feshbach resonance tuning module, and an output module.

[0027] like Figure 2 As shown, the multimode gain module includes a pump source 1, a first collimator 2, a first reflector 3, a dichroic mirror 4, a second collimator 5, and a multimode gain medium 6. The pump source 1 is a high-power semiconductor laser, with its output wavelength matching the absorption peak of the multimode gain medium 6. The first collimator 2 and the second collimator 5 are aspherical lenses used to collimate the diverging beam into a parallel beam. The first reflector 3 is a high-reflectivity plane mirror used to change the propagation direction of the pump light. The dichroic mirror 4 has high transmission of the pump light and high reflection of the signal light, achieving beam combining of the pump light and the signal light. The multimode gain medium 6 is made of doped fiber or crystal, providing gain for the multimode optical field.

[0028] The saturable absorber module uses a saturable absorber 7, which is made of graphene or carbon nanotube material. It utilizes the saturable absorption characteristics to shape continuous light into a pulsed light signal. The pulse width can be adjusted by adjusting the parameters of the saturable absorber 7.

[0029] The Feshbach resonant tuning module includes a quarter-wave plate 8, a half-wave plate 9, and a frequency reflectivity curve tuning device 10. The quarter-wave plate 8 and half-wave plate 9 work together to adjust the polarization state of the signal light, matching its polarization direction with the subsequent optical path. The frequency reflectivity curve tuning device 10 is a position-adjustable mirror; its position is controlled by a precision displacement stage to change the cavity length of the resonant cavity, thereby tuning the reflectivity of different frequency components. Its reflectivity curve is shown in the figure. Figure 3 As shown.

[0030] The output module includes a second reflector 11 and a beam splitter 12. The second reflector 11 is a high-reflectivity plane mirror used to adjust the propagation direction of the signal light; the beam splitter 12 has a splitting ratio of 1:9, where 10% of the light is used as the output laser and 90% of the light returns to the resonant cavity to maintain oscillation.

[0031] The working process of this embodiment is as follows: The pump light emitted from the pump source 1 is collimated by the first collimator 2, reflected by the first reflecting mirror 3 to the dichroic mirror 4, transmitted through the dichroic mirror 4, and focused by the second collimator 5 into the multimode gain medium 6, exciting the multimode gain medium 6 to generate signal light; the signal light oscillates in the resonant cavity, and forms a pulse signal after passing through the saturable absorber 7; the pulse signal is sequentially passed through the quarter-wave plate 8 and the half-wave plate 9 to adjust the polarization state, and then reflected by the frequency reflectivity curve tuning device 10. At this time, by adjusting the position of the frequency reflectivity curve tuning device 10, the cavity length is changed so that the gain curves of different frequencies and the mode gain curves of the multimode gain medium 6 satisfy the resonance relationship (e.g., Figure 4 As shown), a Feshbach-like resonance is formed to achieve directional gain distribution between modes; the modulated pulse signal is reflected by the second reflector 11 to the optical beam splitter 12, and the optical beam splitter 12 outputs 10% of the signal light as the output laser.

[0032] Through the above implementation methods, dynamic control of the laser output mode can be achieved, high-order mode interference can be suppressed or special light fields such as vortex beams can be generated, and the energy utilization rate can be improved by more than 30% compared with the traditional spatial light modulator control method. It is suitable for ultra-precision processing, high-speed communication and other scenarios.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A mode-locked laser based on a Feshbach-like resonance, characterized in that The application relates to a laser device, which comprises a multimode gain module, a saturable absorption module, a Feshbach resonance tuning module and an output module arranged in sequence along an optical path. The multimode gain module is used for providing light signal energy and generating a multimode light field; the saturable absorption module is used for forming a pulse signal. The Feshbach resonance tuning module cooperates with the multimode gain module to build a coupling channel between modes and introduce a Feshbach resonance, so that directional distribution of gain between different modes is realized. The output module is used for outputting a regulated laser signal; the Feshbach resonance tuning module is used for making different frequency gain curves and mode gain curves of the multimode gain module satisfy a resonance relationship, so that regulation of mode distribution of the laser output light field is realized.

2. The mode controlled laser based on Feshbach-like resonance according to claim 1, characterized in that: The multimode gain module comprises a pump source, a first collimator, a first reflector, a dichroic mirror, a second collimator and a multimode gain medium; pump light emitted by the pump source is collimated by the first collimator, the direction of the pump light is adjusted by the first reflector, and then the pump light is combined with signal light in a resonant cavity through the dichroic mirror; the combined light beam is guided into the multimode gain medium through the second collimator, and the signal light and the pump light interact in the multimode gain medium to generate a multimode light field.

3. The mode-locked laser based on Feshbach-like resonance according to claim 1, wherein: The saturable absorption module comprises a saturable absorber or an artificial saturable absorption component, and is used for forming continuous light into pulsed light signals through a saturable absorption effect.

4. The mode-locked laser based on Feshbach-like resonance according to claim 1, wherein: The Feshbach resonance tuning module comprises a polarization control part and a frequency reflectivity curve tuning device; the polarization control part is used for adjusting the polarization state of the signal light in the resonant cavity; and the frequency reflectivity curve tuning device is used for tuning the reflectivity of different frequency components of the signal light in the resonant cavity to affect the gain curves of the different frequency components.

5. A mode-locked laser based on Feshbach-like resonance according to claim 4, characterized in that: The polarization control part comprises a 1 / 4 wave plate and a 1 / 2 wave plate, which are arranged in sequence on the optical path and are used for cooperatively adjusting the polarization state of the signal light.

6. The mode-locked laser based on quasi-Feshbach resonance according to claim 4, characterized in that: The frequency reflectivity curve tuning device is a position-adjustable reflector, which adjusts the reflectivity of different frequency components by changing the resonant cavity length.

7. The mode-locked laser based on quasi-Feshbach resonance according to claim 1, characterized in that: The formation condition of the Feshbach resonance is that the frequency gain curve after tuning of the frequency reflectivity curve tuning device and the mode gain curve of the multimode gain medium satisfy a resonance relationship, so that the modes in the multimode gain medium form a resonance pair and realize directional distribution of gain between modes.

8. The mode-locked laser based on quasi-Feshbach resonance according to claim 1, characterized in that: The output module comprises a second reflector and an optical beam splitter; the second reflector is used for adjusting the propagation direction of the signal light; and the optical beam splitter guides out the signal light in the resonant cavity as output laser light according to a preset ratio.

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