Multi-mode laser frequency comb device and degenerate multi-mode control method

Abstract

The present invention proposes a multimode laser frequency comb device and a degenerate multimode control method. The device includes a diamond crystal, an optical frequency degeneration module, and a degeneracy control module. Based on the multimode laser frequency comb device, the present invention applies stress to the diamond crystal according to the degenerate multimode control method, regulating the lattice constant of the diamond crystal, thereby regulating the degeneracy of Raman vibrations and controlling the optical frequency degeneration mode. This converts an existing single-mode laser comb into a multimode laser comb output. This can generate a multimode optical frequency comb consisting of a single mode or multiple single-mode frequency combs with spectral width spacing. This multimode optical frequency comb has the advantages of wide wavelength coverage, large spectral spacing, and multiple spectral width spacings that are tunable.

Description

Technical Field

[0001] The present invention relates to the field of solid laser technology, and in particular to a multi-mode laser optical frequency comb device and a degenerate multi-mode control method. Background Art

[0002] Optical frequency combs play an important role in the fields of lidar, optical atomic clocks, optical communications, and distance measurement. Existing optical frequency comb generation technologies mainly include mode-locked laser optical frequency combs based on ultrashort pulse technology, Kerr microcavity optical frequency combs, and electro-optical frequency combs. Due to the complexity of the technology and the type of light source, the wavelength range of optical frequency combs is mostly concentrated at 1 μm, and there is only a single spectral width spacing, namely a single-mode optical frequency comb. For example, the maximum spectral width of the electro-optical frequency comb is 132 nm. This limits the application of optical frequency combs in special scenarios such as wide wavelength ranges and tunable spectral width spacing. Diamond crystals provide a new technical solution for optical frequency combs due to their advantages such as high thermal conductivity, large Raman frequency shift, and high gain coefficient. However, diamond crystals can only produce single-mode optical frequency combs under normal circumstances, and the spectral width spacing cannot be tuned. In summary, there is an urgent need for a multi-mode laser optical frequency comb device and control method that meets the requirements of wide wavelength coverage, large spectral width spacing, multiple spectral width spacing and tunable spectral width spacing, so as to provide a feasible technical solution for the application of single-mode and multi-mode optical frequency combs with tunable spectral width spacing. Summary of the Invention

[0003] This invention provides a multimode laser frequency comb device and a degenerate multimode control method, offering a novel technical solution for optical frequency combs. It boasts the advantages of a wide wavelength coverage range, large spectral width spacing, multiple adjustable spectral width spacings, and the ability to output single-mode or multimode laser frequency combs. It addresses the challenges of existing optical frequency comb technology, which suffers from limited availability of light sources, a narrow wavelength range, small spectral width spacing, and a single spectral width spacing.

[0004] A first embodiment of the present invention provides a multi-mode laser optical frequency comb device, comprising a diamond crystal, an optical frequency comb generation module, and a degeneracy control module:

[0005] The diamond crystal comprises two oppositely arranged light-transmitting end faces and two relatively parallelly arranged stress-applying surfaces;

[0006] A degeneracy control module is used to control the lattice constant of the diamond crystal, thereby controlling the degeneracy of the Raman vibration and the mode of the optical frequency comb. The degeneracy control module includes an analysis controller, a stress controller, and a degeneracy detector that are communicatively connected.

[0007] The analysis controller is used to calculate the center frequency of the optical frequency comb obtained by exciting the diamond crystal and the theoretical applied stress value according to the setting parameters. , and generate the spectrum of the multi-mode laser frequency comb under theoretical conditions ;

[0008] The stress controller includes a stress shaping feedback sheet, a diamond anvil, a stress applicator, a detection ray transmitter coaxially arranged on both sides of the stress application surface, and a ray feedback controller; the ray feedback controller receives the theoretical applied stress value signal, and transmits it to the stress applicator; the stress applicator applies the theoretical stress value The stress is applied to the diamond crystal through the diamond anvil and the stress shaping feedback plate; the detection ray transmitter emits detection rays and diffracts with the stress shaping feedback plate and the diamond crystal, and the ray detector feeds back the detected diffraction signal to the ray feedback controller and calculates the actual applied stress value. , the actual applied stress value With the theoretical applied stress value The stress difference value , and according to the stress difference value adjusting the magnitude of the stress applied by the stress applicator;

[0009] The degeneracy detector includes an excitation laser light source, a frequency detector and a spectrum analysis controller. The excitation laser light source excites the diamond crystal to generate the multi-mode laser optical frequency comb and transmits it to the frequency detector; the frequency detector detects the spectrum of the multi-mode laser optical frequency comb and transmits it to the spectrum analysis controller; the spectrum analysis controller analyzes and obtains the actual spectrum diagram , and transmits it to the analysis controller; the analysis controller analyzes the actual spectrum Spectrum diagram of multi-mode laser frequency comb under the theoretical conditions The difference in spectral width , and according to the spectral width spacing difference value , calculate the stress deviation And feedback to the stress controller, according to the stress difference value adjusting the magnitude of the stress applied by the stress applicator;

[0010] The optical frequency comb generation module is used to pump the stressed diamond crystal to generate a single-mode or multi-mode optical frequency comb, wherein the multi-mode optical frequency comb includes a plurality of single-mode optical frequency combs with different spectral widths.

[0011] According to one embodiment of the present invention, a Raman resonant cavity mirror is included, wherein the Raman resonant cavity mirror includes a first Raman resonant cavity mirror and a second Raman resonant cavity mirror arranged on both sides of the light-transmitting end face of the diamond crystal, and the first Raman resonant cavity mirror and the second Raman resonant cavity mirror are coated cavity mirrors; or

[0012] The two light-transmitting end faces of the diamond crystal are film-coated end faces.

[0013] According to one embodiment of the present invention, a beam shaping mirror is included to shape the pump laser beam and the optical frequency comb beam, and is optically coaxially placed with the pump laser beam or the laser optical frequency comb.

[0014] According to one embodiment of the present invention, the degeneracy detector further includes a Raman enhanced cavity mirror, which includes a first Raman enhanced cavity mirror and a second Raman enhanced cavity mirror arranged on both sides of the light-transmitting end face of the diamond crystal, and the first Raman enhanced cavity mirror and the second Raman enhanced cavity mirror are coated cavity mirrors; or

[0015] The two light-transmitting end faces of the diamond crystal are film-coated end faces.

[0016] According to one embodiment of the present invention, the theoretical applied stress value , theoretical spectral width spacing , the stress crystal direction satisfies:

[0017]

[0018] in, 、 is the coordinate of the stress acting crystal direction, is the mass of the i-th atom, which is m here. represents the Hamiltonian operator, is the vibration amplitude, is the equilibrium position of the atoms, For time, is the displacement of the atomic principle equilibrium position, is the nth spectral width spacing, n is the working degeneracy, n=1, 2, 3.

[0019] According to one embodiment of the present invention, the theoretical spectral width spacing The corresponding Raman activity intensity of the diamond crystal satisfy:

[0020]

[0021]

[0022]

[0023] in, is the linear polarizability Normal coordinates of Raman-active vibrational modes The derivative of .

[0024] According to one embodiment of the present invention, the multi-mode laser optical frequency comb includes one spectral width spacing or multiple spectral width spacings.

[0025] According to one embodiment of the present invention, the multi-mode laser frequency comb includes lasers of one frequency or multiple frequencies.

[0026] According to one embodiment of the present invention, the stress controller also includes a stress protection member, which is arranged between the two stress shaping feedback plates and located on the non-light-emitting surface on the side of the diamond crystal. The tensile fracture stress and compressive fracture stress of the stress protection member are both weaker than those of the diamond crystal. The stress protection member is communicatively connected to the analysis controller. When the stress protection member is not broken, a positive correlation signal is transmitted to the analysis controller. When the stress protection member is broken, a negative correlation signal is transmitted to the analysis controller. When the analysis controller receives the negative correlation signal, it stops the stress controller from applying stress to the diamond crystal.

[0027] A second aspect of the present invention provides a degenerate multi-mode control method for the multi-mode laser optical frequency comb device described above. The degenerate multi-mode control method includes:

[0028] Step 1: Set the parameters of the analysis controller, including the pump laser wavelength, theoretical spectrum width spacing, , stress action crystal direction, preset stress difference value, preset spectral width spacing difference value, working degeneracy n, the analysis controller calculates the center frequency of the excited optical frequency comb, the theoretical applied stress value according to the parameters , and generate the spectrum of the multi-mode laser frequency comb under theoretical conditions ;

[0029] Step 2: applying stress to the diamond crystal, and the analysis control 1 converts the theoretical applied stress value The ray feedback controller transmits the theoretical stress value to the stress applicator, and the stress applicator converts the theoretical stress value into Applying stress to the stress shaping feedback piece and the diamond crystal through the diamond anvil;

[0030] Step 3: Detect the stress applied to the diamond crystal. The detection ray transmitter emits a detection ray, which reacts with the stress shaping feedback plate and the diamond crystal to cause diffraction. The ray detector feeds back the detected diffraction ray signal to the ray feedback controller. The ray feedback controller screens and analyzes the diffraction ray signal and calculates the actual applied stress value using the diffraction ray signal of the stress shaping feedback plate. , and analyze the actual applied stress value With the theoretical applied stress value The stress difference value , and the stress difference value Transmit to the stress applicator, repeat steps 2 and 3 until the stress difference value Less than the preset stress difference value;

[0031] Step 4: Detect and control the degeneracy of the diamond crystal. The excitation laser light source emits laser to excite the diamond crystal to generate an optical frequency comb. The frequency detector detects the spectrum of the multi-mode laser optical frequency comb and transmits it to the spectrum analysis controller. The spectrum analysis controller analyzes and obtains the actual spectrum diagram. , and transmits it to the analysis controller, which analyzes the actual spectrum Spectrum diagram of multi-mode laser frequency comb under the theoretical conditions The difference in spectral width The analysis controller is based on the spectral width difference value , calculate the stress deviation And transmit it to the stress controller, according to the stress difference value Adjust the stress applied by the stress applicator; repeat steps 2, 3, and 4 until the spectral width difference value is smaller than the preset spectral width spacing difference value;

[0032] Step 5: Generate a multi-mode optical frequency comb. The degeneracy detector stops working, and the optical frequency comb generation module starts working. The pump laser light source emits a pump laser to pump the diamond crystal to generate a multi-mode laser optical frequency comb. The remaining portion of the pump laser and the multi-mode laser optical frequency comb are transmitted to the optical comb detector. The optical comb detector analyzes and obtains the required actual spectrum diagram, and transmits it to the analysis controller to obtain the required actual spectrum diagram.

[0033] The present invention provides a multi-mode laser optical frequency comb device and a degenerate multi-mode control method. The device is characterized by employing a degeneracy control module to regulate the lattice constant of the diamond crystal, thereby regulating the degeneracy of the Raman vibration and controlling the optical frequency comb mode. The optical frequency comb generation module is then used to adjust the existing single-mode laser optical comb into a single-mode or multi-mode laser optical frequency comb output with tunable spectral width spacing. Compared with existing laser optical combs, this device has the advantage of being able to achieve single-mode or multi-mode laser optical frequency combs with tunable spectral width spacing, offering the advantages of a wide wavelength coverage range, large spectral width spacing, and multiple spectral width spacings that can be tuned. This device overcomes the limitations of existing laser optical frequency comb technology in terms of tunable spectral width spacing, combined distance measurement using multiple optical frequency combs, a narrow wavelength coverage range, and small spectral width spacing, providing a novel technical solution for applications in special scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 1 is a schematic structural diagram of a first multi-mode laser frequency comb device provided by an embodiment of the present invention;

[0036] Figure 2 1 is a schematic structural diagram of a second multi-mode laser frequency comb device provided by an embodiment of the present invention;

[0037] Figure 3 1 is a schematic structural diagram of a third multi-mode laser frequency comb device provided by an embodiment of the present invention;

[0038] Figure 4 1 is a schematic structural diagram of a fourth multi-mode laser frequency comb device provided by an embodiment of the present invention;

[0039] Figure 5 3 is a schematic structural diagram of a fifth multi-mode laser frequency comb device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0041] In the following detailed description, many specific details are set forth in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is intended only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0042] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0043] Figure 1The first multi-mode laser frequency comb device according to the present invention comprises a diamond crystal 1 , an optical frequency degeneration module, and a degeneracy control module 3 .

[0044] The diamond crystal 1 includes two oppositely arranged light-transmitting end faces 11 and two relatively parallel stress-applying surfaces 12. There is no limitation on the specific shape of the diamond crystal 1, and it can be, for example, a hexahedron, an octahedron or an irregular shape. When the diamond crystal is a hexahedron, the two oppositely arranged light-transmitting end faces are perpendicular to the two relatively parallel stress-applying surfaces. When the diamond crystal is an octahedron, the two oppositely arranged light-transmitting end faces are adjacent to or separated from the two relatively parallel stress-applying surfaces. When the diamond crystal is an irregular shape, the two oppositely arranged light-transmitting end faces and the two relatively parallel stress-applying surfaces are different end faces.

[0045] The degeneracy control module 3 is used to control the lattice constant of the diamond crystal 1, thereby adjusting the degeneracy of the Raman vibration and controlling the mode of the multi-mode laser optical frequency comb. The degeneracy control module 3 includes an analysis controller 31, a stress controller, and a degeneracy detector 33, which are communicatively connected.

[0046] The analysis controller 31 is used to calculate the center frequency of the optical frequency comb obtained by exciting the diamond crystal 1 and the theoretical applied stress value according to the set parameters. , and generate the spectrum of the multi-mode laser frequency comb under theoretical conditions .

[0047] The stress controller includes a stress shaping feedback sheet, a diamond anvil, a stress applicator, which are sequentially arranged on both sides of the stress application surface, a detection ray transmitter and a ray feedback controller which are coaxially arranged with the stress application surface; the ray feedback controller 321 receives the theoretical applied stress value signal, and transmits it to the stress applicator 322; the stress applicator 322 applies the theoretical stress value The stress is applied to the diamond crystal 1 through the diamond anvil 323 and the stress shaping feedback plate 324; the detection ray transmitter 325 emits detection rays and diffracts with the stress shaping feedback plate 324 and the diamond crystal 1, and the ray detector 326 feeds back the detected diffraction signal to the ray feedback controller 321 and calculates the actual applied stress value. , the actual applied stress value With the theoretical applied stress value The stress difference value , and according to the stress difference value The magnitude of the stress applied by the stress applicator 322 is adjusted.

[0048] The degeneracy detector 33 includes an excitation laser light source 331, a frequency detector 332, and a spectrum analysis controller. The excitation laser light source 331 excites the diamond crystal 1 to generate the multi-mode laser optical frequency comb and transmits it to the frequency detector 332; the frequency detector 332 detects the spectrum of the multi-mode laser optical frequency comb and transmits it to the spectrum analysis controller; the spectrum analysis controller analyzes and obtains the actual spectrum diagram , and transmits it to the analysis controller 31; the analysis controller 31 analyzes the actual spectrum Spectrum diagram of multi-mode laser frequency comb under the theoretical conditions The difference in spectral width , and according to the spectral width spacing difference value , calculate the stress deviation And feedback to the stress controller, according to the stress difference value The magnitude of the stress applied by the stress applicator 322 is adjusted.

[0049] After the stress applied to the diamond crystal 1 is adjusted by the degeneracy control module 3 to adjust the lattice constant of the diamond crystal 1, the optical frequency comb generation module pumps the diamond crystal 1 to output a single-mode or multi-mode optical frequency comb, wherein the multi-mode optical frequency comb may include multiple single-mode optical frequency combs with different spectral widths.

[0050] In some embodiments, a pump laser light source pumps the diamond crystal 1 to generate a laser optical frequency comb, which can be measured by transmitting it to an optical frequency comb detector.

[0051] The multimode laser frequency comb device provided by this invention applies stress to a diamond crystal 1 via a degeneracy control module 3, causing the triple-degenerate Raman vibration mode of the diamond crystal 1 to degenerate, thereby generating a single-mode or multi-mode optical frequency comb. The spectral spacing of the frequency comb can be adjusted by controlling the magnitude and orientation of the applied stress. The multimode laser frequency comb device of this embodiment can output single-mode or multi-mode optical frequency combs with the advantages of wide wavelength coverage, large spectral spacing, and multiple tunable spectral spacing. This provides a feasible technical solution for the application of single-mode and multi-mode optical frequency combs with tunable spectral spacing.

[0052] In some embodiments, see Figure 2As shown, the multi-mode laser frequency comb device may further include a Raman resonant cavity mirror 222, which includes a first Raman resonant cavity mirror 2221 and a second Raman resonant cavity mirror 2222, which are arranged on both sides of the light-transmitting end face 11 of the diamond crystal 1. The first Raman resonant cavity mirror 2221 and the second Raman resonant cavity mirror 2222 may be coated mirrors, wherein the first Raman resonant cavity mirror 2221 has high transmittance to the pump laser and high reflection to the multi-mode laser frequency comb, and the second Raman resonant cavity mirror 2222 has high reflection to the pump laser and partial reflection to the multi-mode laser frequency comb, so as to reduce the output threshold of the multi-mode laser frequency comb and improve the conversion efficiency.

[0053] In other embodiments, a coating can be directly applied to the two light-transmitting end faces 11 of the diamond crystal 1. The pump laser input coating provides high transmittance to the pump laser and high reflectivity to the multimode laser frequency comb. The multimode laser frequency comb output coating provides high reflectivity to the pump laser and partial reflectivity to the multimode laser frequency comb. Direct coating on the end faces of the diamond crystal 1 can lower the output threshold of the multimode laser frequency comb, increase conversion efficiency, and improve beam quality.

[0054] In some embodiments, see Figure 2 As shown, the multimode laser frequency comb device can also include an optically coaxially positioned beam shaping mirror 221 for shaping the pump laser or laser frequency comb beam to meet applicable requirements. Beam shaping mirror 221 can include a lens, a half-glass, and a polarizer to optimize and control the spot radius, divergence angle, and polarization state of the pump laser or laser frequency comb.

[0055] In some embodiments, see Figure 2 As shown, the degeneracy detector 33 may also include Raman-enhanced cavity mirrors 334. The Raman-enhanced cavity mirrors 334 include a first Raman-enhanced cavity mirror 3341 and a second Raman-enhanced cavity mirror 3342, disposed on either side of the light-transmitting end face 11 of the diamond crystal 1. The first Raman-enhanced cavity mirror 3341 and the second Raman-enhanced cavity mirror 3342 may be coated cavity mirrors. The first Raman-enhanced cavity mirror 3341 has high transmittance for the excitation laser and high reflectivity for the detection multimode laser frequency comb. The second Raman-enhanced cavity mirror 3342 has high reflectivity for the excitation laser and partial reflectivity for the detection multimode laser frequency comb, thereby lowering the threshold for detecting the multimode laser frequency comb output and improving conversion efficiency. In another embodiment, the two light-transmitting end faces of the diamond crystal 1 are coated end faces. The coated end face for the excitation laser input has high transmittance for the excitation laser and high reflectivity for the detection multimode laser frequency comb, while the coated end face for the detection multimode laser frequency comb output has high reflectivity for the excitation laser and partial reflectivity for the detection multimode laser frequency comb.

[0056] In some embodiments, continue to refer to Figure 1 and Figure 2As shown, the theoretical applied stress value , theoretical spectral width spacing , the stress crystal direction satisfies:

[0057] (1)

[0058] in, 、 is the coordinate of the stress acting crystal direction, is the mass of the i-th atom, which is m here. represents the Hamiltonian operator, is the vibration amplitude, is the equilibrium position of the atoms, For time, is the displacement of the atomic principle equilibrium position, The nth spectral width spacing, where n = 1, 2, or 3, is the spectral width spacing of multi-mode optical frequency sparseness. The relationship between the theoretical spectral width spacing and the theoretical applied stress value is optimized and adjusted through the formula to achieve the goal of selecting the appropriate crystal orientation and stress based on the spectral width spacing required for use.

[0059] In some embodiments, continue to refer to Figure 1 and Figure 2 As shown, the theoretical spectral width spacing Corresponding Raman activity intensity of diamond crystal satisfy:

[0060] (2)

[0061] (3)

[0062] (4)

[0063] in, is the linear polarizability Normal coordinates of Raman-active vibrational modes The derivative of the theoretical spectral width is When it is 0, the single-mode optical frequency comb with this theoretical spectral width does not exist, and the Raman activity intensity When it is not 0, a single-mode optical frequency comb with this theoretical spectral width spacing exists in the multi-mode optical frequency comb.

[0064] In some embodiments, the diamond crystal lattice can be controlled by the degeneracy control module to achieve an optical frequency comb output with one or multiple spectral widths, depending on actual needs. The output optical frequency comb can include lasers of one frequency or multiple frequencies.

[0065] In some embodiments, see Figure 3As shown, the stress controller may also include a stress protection member, which is arranged between the two stress shaping feedback plates 324 and located on the non-light-emitting surface on the side of the diamond crystal 1. The tensile fracture stress and compressive fracture stress of the stress protection member are both weaker than the maximum tensile fracture and compressive fracture stress of the diamond crystal 1. It is communicatively connected to the analysis controller 31. When the stress protection member is not broken, it is an insulator and cannot transmit electrical signals, and transmits a positive correlation signal to the analysis controller 31. When the stress protection member is broken, it suddenly becomes a conductor and can transmit electrical signals, and transmits a negative correlation signal to the analysis controller 31. When the analysis controller 31 receives the negative correlation signal, it stops the stress controller from applying stress to the diamond crystal 1.

[0066] In some embodiments, see Figure 4 As shown, the optical frequency comb generation module includes multiple wavelength pump laser light sources, which pump diamond crystals to generate multiple optical frequency combs in different wavelength ranges to meet the demand for multi-wavelength laser optical frequency comb output under the same spectral width spacing of the optical frequency combs.

[0067] The present invention also provides a degenerate multi-mode control method, which includes:

[0068] Step 1: Set the parameters of the analysis controller 31, including the pump laser wavelength, theoretical spectrum width spacing, , stress action crystal direction, preset stress difference value, preset spectral width spacing difference value, working degeneracy n, the analysis controller 31 calculates the center frequency of the excited optical frequency comb, the theoretical applied stress value according to the parameters , and generate the spectrum of the multi-mode laser frequency comb under theoretical conditions ;

[0069] Step 2: applying stress to the diamond crystal, and the analysis controller 31 converts the theoretical applied stress value The ray feedback controller 321 transmits the theoretical stress value to the stress applicator 322. The stress is applied to the stress shaping feedback piece 324 and the diamond crystal 1 through the diamond anvil 323;

[0070] Step 3: Detect the stress applied to the diamond crystal. The detection ray transmitter 325 emits a detection ray and diffracts it with the stress shaping feedback plate 324 and the diamond crystal 1. The ray detector 326 feeds back the detected diffraction ray signal to the ray feedback controller 321. The ray feedback controller 321 screens and analyzes the diffraction ray signal and calculates the actual applied stress value using the diffraction ray signal of the stress shaping feedback plate 324. , and analyze the actual applied stress value With the theoretical applied stress value The stress difference value , and the stress difference value Transmit to the stress applicator 322, repeat step 2 and step 3 until the stress difference value Less than the preset stress difference value;

[0071] Step 4: Detect and control the degeneracy of the diamond crystal. The excitation laser light source 331 emits laser to excite the diamond crystal 1 to generate a multi-mode laser optical frequency comb. The frequency detector 332 detects the spectrum of the multi-mode laser optical frequency comb and transmits it to the spectrum analysis controller. The spectrum analysis controller analyzes and obtains the actual spectrum diagram. , and transmits it to the analysis controller 31, the analysis controller 31 analyzes the actual spectrum Spectrum diagram of multi-mode laser frequency comb under the theoretical conditions The difference in spectral width The analysis controller 31 is based on the spectrum width spacing difference value , calculate the stress deviation And transmit it to the stress controller, according to the stress difference value Adjust the stress applied by the stress applicator 322; repeat steps 2, 3, and 4 until the spectral width difference value is smaller than the preset spectral width spacing difference value;

[0072] Step 5: Generate a multi-mode optical frequency comb. The degeneracy detector 33 stops working, and the optical frequency comb generation module starts working. The pump laser light source emits a pump laser to pump the diamond crystal 1 to generate a multi-mode laser optical frequency comb. The remaining part of the pump laser and the multi-mode laser optical frequency comb are transmitted to the optical comb detector 23. The optical comb detector 23 analyzes and obtains the required actual spectrum diagram, and transmits it to the analysis controller 31 to obtain the required actual spectrum diagram.

[0073] The degenerate multi-mode control method of this embodiment applies stress to the diamond crystal 1 via the degeneracy control module 3, causing the triple-degenerate Raman vibration mode of the diamond crystal 1 to degenerate. This modulates the mode of the optical frequency comb, enabling the diamond crystal to generate single-mode or multi-mode optical frequency combs. The spectral width spacing of the optical frequency comb can be adjusted by controlling the magnitude and orientation of the applied stress. Furthermore, depending on actual needs, the optical frequency comb can be output with a single or multiple spectral width spacings, and the optical frequency comb can contain single-frequency or multi-frequency lasers. The single-mode or multi-mode optical frequency comb output by the multi-degenerate multi-mode control method of this embodiment has the advantages of wide wavelength coverage, large spectral width spacing, and multiple spectral width spacings with tunable spectral width spacing. This provides a feasible technical solution for the application of single-mode and multi-mode optical frequency combs with tunable spectral width spacing.

[0074] The multi-mode laser optical frequency comb device and the degenerate multi-mode control method of the present invention are described in detail below based on specific embodiments.

[0075] Example 1

[0076] The first multi-mode laser frequency comb device provided in this embodiment is Figure 1 As shown, it includes a diamond crystal 1, a set of optical frequency sparseness generation modules, and a set of degeneracy control modules 3.

[0077] Diamond crystal 1 is 2*2*7mm 3 The standard Raman frequency shift of a six-sided cuboid is 1332.5 cm -1 , used to generate and output multi-mode laser frequency comb, where two opposite 2*2mm 2 Surface 11 is the light-transmitting surface, and two relatively parallel 2*7mm 2 Surface 12 is a stress-applying surface.

[0078] An optical frequency comb generation module is used to pump the diamond crystal 1 to generate the multi-mode laser optical frequency comb, including a pump laser light source and an optical frequency comb detector that are optically coaxially placed in sequence; the pump laser emitted by the pump laser light source is a femtosecond laser with a central wavelength of 532 nm, a pulse width of 100 fs, a repetition rate of 1 kHz, an average power of 1 mW, and linearly polarized light.

[0079] The degeneracy control module 3 is used to control the lattice constant of the diamond crystal 1, thereby controlling the degeneracy of the Raman vibration and controlling the mode of the multi-mode laser optical frequency comb, and includes an analysis controller 31, a stress controller, and a degeneracy detector 33 that are communicatively connected; the degeneracy control module 3 relies on a degenerate multi-mode control method.

[0080] The adjustment process of the multi-mode laser frequency comb device provided in this embodiment is as follows:

[0081] Set the parameters of the analysis controller 31, the pump laser wavelength is 532 nm, the stress action crystal direction is

[100] crystal direction, the working degeneracy n=2, and the theoretical spectrum width spacing is set. 1385 cm -1 、1354 cm -1 , the preset stress difference value is ±0.2GPa, and the preset spectral width spacing difference value is 1%. The analysis controller 31 calculates the center frequencies of the excited optical frequency comb based on the parameters as 574.3 nm and 573.3 nm. Calculation, theoretical applied stress value The spectrum of the multi-mode laser frequency comb described in the theoretical conditions is generated at 47.7 GPa. 463.7 nm, 495.5 nm, 532 nm, 574.3 nm, 624 nm, 465 nm, 496.3 nm, 532 nm, 573.3 nm, 621.5 nm;

[0082] Stress is applied to the diamond crystal, and the analysis controller 31 converts the theoretical applied stress value The ray feedback controller 321 transmits the theoretical stress value to the stress applicator 322. The stress is applied to the stress shaping feedback piece 324 and the diamond crystal 1 through the diamond anvil 323;

[0083] The stress applied to the diamond crystal is detected. The detection ray transmitter 325 emits a detection ray and reacts with the stress shaping feedback plate 324 and the diamond crystal 1 to cause diffraction. The ray detector 326 feeds back the detected diffraction ray signal to the ray feedback controller 321. The ray feedback controller 321 screens and analyzes the diffraction ray signal and calculates the actual applied stress value using the diffraction ray signal of the stress shaping feedback plate 324. The actual applied stress value is 40 GPa. With the theoretical applied stress value The stress difference value The value is 7.7 GPa, which is greater than the preset stress difference value of 0.2 GPa. Repeat steps 2 and 3 to calculate the actual applied stress value. It is 47.6 GPa, which is less than the preset stress difference value of 0.2 GPa.

[0084] To detect and control the degeneracy of the diamond crystal, the excitation laser light source 331 emits laser to excite the diamond crystal 1 to generate a multi-mode laser optical frequency comb, and the frequency detector 332 detects the spectral width of the multi-mode laser optical frequency comb to be 1385 cm -1 、1354 cm -1 , and transmits it to the spectrum analysis controller; the spectrum analysis controller analyzes and obtains the actual spectrum diagram , and transmits it to the analysis controller 31, the analysis controller 31 analyzes the actual spectrum Spectrum diagram of multi-mode laser frequency comb under the theoretical conditions The difference in spectral width The measured two spectral widths of the multi-mode optical frequency comb are 1385.53 cm and 0.038% and 0.096%, respectively. -1 、1354.13 cm -1 , according to the corresponding Raman activities are 、 The spectral width difference value Less than 1% of the preset spectral width spacing difference value.

[0085] A multimode optical frequency comb is generated. The degeneracy detector 33 stops operating, and the optical frequency comb generation module starts operating. The pump laser light source emits fs of 532 nm pump laser light. After being shaped by the beam shaper 221, it pumps the diamond crystal 1 to generate a multimode laser optical frequency comb. The remaining pump laser light and the multimode laser optical frequency comb are transmitted to the optical comb detector 23. The optical comb detector 23 analyzes the required actual spectrum and transmits it to the analysis controller 31. The required actual spectrum is 463.65 nm, 495.48 nm, 574.33 nm, 623.99 nm, 683.04 nm; 465 nm, 496.25 nm, 573.30 nm, 621.55 nm, and 687.67 nm, respectively. The repetition rate is 1 kHz, the average power is 0.6 mW, and the light is linearly polarized.

[0086] The wavelength detector 31 detects the Raman laser wavelength 21 information output by the diamond crystal 2, which are 465.94 nm, 496.78 nm, 532 nm, 572.59 nm, 619.88 nm, and 675.7 nm, and transmits the information to the controller 30;

[0087] At the same time, the detection ray transmitter 321 in the stress detector 32 emits a detection ray 3211. The detection ray 3211 acts on the stress shaping stage feedback piece 323 and the diamond crystal 2 and diffracts. The diffracted detection ray 3212 is emitted to the detection ray receiver 322. The detection ray receiver 322 screens and analyzes the diffraction peak corresponding to the stress shaping stage feedback piece 323, and compares it with the standard diffraction peak of the stress shaping stage feedback piece 323. By using the diffraction peak deviation of the stress shaping feedback piece 323 and the state equation, it is analyzed that the stress applied by the stress applicator 33 to the diamond crystal 2 at this time is 0 GPa. By screening and analyzing the diffraction peak corresponding to the diamond crystal 2 and comparing it with the standard diffraction peak of the diamond crystal 2, it is analyzed that the crystal direction of the stress action is <100> Crystal direction, and analyze the diffracted detection ray 3212 to obtain the lattice fringe information of the diamond crystal 2, and transmit the stress magnitude, stress action crystal direction and the lattice fringe information of the diamond crystal 2 to the controller 30;

[0088] The controller 30 receives the lattice fringe information of the diamond crystal 2 in a periodic arrangement. At this time, the controller 30 controls the degenerate module 3 to work normally. According to the lattice fringe information of the diamond crystal 2 and the crystal direction of the stress action, <100> The controller 30 indicates that the optical frequency comb spectrum has a wide spacing range of 535 – 1460 cm -1 At this time, the first spectral width of the optical frequency comb is selected to be 1385 cm -1 The triple degenerate vibration mode of the diamond crystal 2 is determined according to the degradation degree of the

[100] crystal orientation when it is subjected to stress. The controller 30 displays that the second spectrum width of the optical frequency comb is 1354 cm -1 The controller 30 analyzes the Raman wavelength 21 information detected by the wavelength detector 31 and obtains that there is only one optical frequency comb spectrum with a wide spacing of 1332.5 cm -1 , the Raman vibration activity corresponding to this spectral width spacing is , the actual spectral width spacing, the first spectral width spacing of the optical frequency comb and the stress action crystal direction <100> Bring in In the figure, it is found that the actual stress applied by the stress applicator 33 to the diamond crystal 2 is 0 GPa, and the theoretical stress to be applied when the first spectral width spacing of the optical frequency comb is reached is -47.7 GPa. A negative value indicates compressive stress. The controller 30 thus obtains a stress adjustment value of -47.7 GPa and communicates it to the stress applicator 33. The stress applicator 33 applies a compressive stress value of 47.7 GPa to the

[100] crystal orientation of the diamond crystal 2 according to the stress adjustment value.

[0089] The above adjustment and control process is repeated until the accuracy of the detected Raman laser wavelength 21 spectral width spacing and the selected first spectral width spacing and second spectral width spacing of the optical frequency comb is within ±1%. When the compressive stress applied by the stress applicator 33 to the diamond crystal 2 is 47.7 GPa, the detected Raman laser wavelength 21 is screened and analyzed as 463.65 nm, 495.48 nm, 574.33 nm, 623.99 nm, 683.04 nm; 465 nm, 496.25 nm, 573.30 nm, 621.55 nm, and 687.67 nm. The two spectral width spacings of the multi-mode optical frequency comb are measured to be 1385.53 cm -1 、1354.13 cm -1 , and the corresponding Raman activities are 、 , which is 1385 cm away from the first spectral width of the optical frequency comb. -1 、The second spectrum width of the optical frequency comb is 1354 cm -1 The errors were 0.038% and 0.096%, respectively, both within the 1% error range. At this point, the degenerate multimode optical frequency comb device met the preset requirements and ceased operation.

[0090] Example 2

[0091] This embodiment provides the first degenerate multi-mode laser frequency comb device, see Figure 2 As shown, the difference between this device and Example 1 is that:

[0092] The pump laser emitted by the laser pump source 331 is a femtosecond laser with a central wavelength of 1064 nm, a pulse width of 200 fs, a repetition rate of 1 KHz, an average power of 3 mW, and linearly polarized light.

[0093] Two 2*7mm diamond crystals 2 The laser input and output end faces.

[0094] The degeneracy detector 33 also includes a Raman enhancement cavity mirror 334, which includes a first Raman enhancement cavity mirror 3341 and a second Raman enhancement cavity mirror 3342 arranged on both sides of the light-transmitting end face 11 of the diamond crystal 1. The excitation laser light source 331, the first Raman enhancement cavity mirror 3341, the diamond crystal 1, and the second Raman enhancement cavity mirror 3342 are optically coaxially placed in sequence.

[0095] The first spectral width of the selected optical frequency comb is 1260 cm -1 、The second spectrum width of the optical frequency comb is 1304 cm -1 , the second spectrum width of the optical frequency comb is 1330 cm -1

[0096] The multi-mode laser frequency comb device provided in this embodiment has an adjustment process similar to that of Example 1. The resulting frequency combs are as follows: 839 nm, 938.2 nm, 1064 nm, 1228.7 nm, 1475.3 nm; 832.8 nm, 934.3 nm, 1064 nm, 1235.4 nm, 1472.7 nm; 829.3 nm, 932.1 nm, 1064 nm, 1239.4 nm, 1484 nm. A multi-mode frequency comb is formed by three single-mode frequency combs with spectral widths of 1260.08 cm. -1 、1304.1 cm -1 、1329.9cm -1 , and the corresponding Raman activities are 、 、 The first spectral width of the optical frequency comb is 1260 cm-1, and the second spectral width of the optical frequency comb is 1304 cm-1. -1 , the second spectrum width of the optical frequency comb is 1330 cm -1 The errors are 0.0063%, 0.0077%, and 0.0075% respectively, and the error range is within 1%.

[0097] Example 3

[0098] The multi-mode laser frequency comb device provided in this embodiment can be found in Figure 3 As shown, the difference between this device and Example 1 is that:

[0099] The stress detector includes stress protection components B1 and B2, which are closely attached between the stress shaping feedback plate 323 and are placed on the side of the plane formed by the diamond crystal 1 and the pump laser 11. Figure 3 A cross-sectional view of a stress detector 32 and a stress applicator 33 including stress protection members B1 and B2, along the pump laser 11, is shown. The tensile and fracture stresses of the stress protection members B1 and B2 are slightly weaker than those of the diamond crystal, and the members are in communication with the controller 30. When the stress protection members B1 and B2 are intact, they transmit a positive correlation signal to the controller 30, which then receives lattice fringe information from the diamond crystal 1 and performs subsequent operations. When the stress protection members B1 and B2 are damaged, they transmit a negative correlation signal to the controller 30, causing the controller 30 to stop the stress applicator 33 from applying stress to the diamond crystal 1, protecting it from damage.

[0100] The degenerate multi-mode laser frequency comb device provided in this embodiment has an adjustment process similar to that in Example 1. The obtained frequency combs are as follows: 464.8 nm, 496 nm, 532 nm, 573.4 nm, 621.8 nm; 466 nm, 496.8 nm, 532 nm, 572.5 nm, 619.6 nm. The measured two spectral widths of the multi-mode frequency comb are 1357.17 cm -1 、1329.31cm -1 , and the corresponding Raman activities are 、 , which is 1357 cm away from the first spectral width of the optical frequency comb. -1 、The second spectrum width of the optical frequency comb is 1329 cm -1 The errors are 0.0125% and 0.0233% respectively, and the error range is within 1%.

[0101] Example 4

[0102] The multi-mode laser frequency comb device provided in this embodiment can be found in Figure 5 As shown, the difference between this device and Example 1 is that:

[0103] The pump laser emitted by the laser pump source 331 is a nanosecond laser with a central wavelength of 2400 nm, a pulse width of 40 ns, a repetition rate of 1 KHz, an average power of 10 W, and linearly polarized light.

[0104] The diamond crystal contains resonant cavities on both sides of the optical collinearity. The first lens 51 of the resonant cavity is highly transparent to the pump laser and highly reflective to the Raman laser. The second lens of the resonant cavity is highly reflective to the pump laser and partially transmits the Raman laser. The transmittance is 50%.

[0105] The adjustment process of the multi-mode laser frequency comb device provided in this embodiment is still the same as that of Example 1. The optical frequency comb obtained is as follows: 1435.2 nm, 1796.2 nm, 2400 nm, 3615.2 nm, 7323.1 nm, 1463.6 nm, 1818.3 nm, 2400 nm, 3528.8 nm, 6662.5 nm. The measured two spectral widths of the multi-mode frequency comb are 1400.56 cm -1 、1332.86 cm -1 , and the corresponding Raman activities are 、 , 1400 cm away from the first spectral width of the optical frequency comb -1 、The second spectrum width of the optical frequency comb is 1332cm -1 The errors are 0.04% and 0.0646% respectively, both within the error range of 1%.

Claims

1. A multi-mode laser optical frequency comb device, comprising a diamond crystal and an optical frequency comb generation module, characterized in that: Also includes a degeneracy control module: The diamond crystal comprises two oppositely arranged light-transmitting end faces and two relatively parallelly arranged stress-applying surfaces; A degeneracy control module is used to control the lattice constant of the diamond crystal, thereby controlling the degeneracy of the Raman vibration and the mode of the optical frequency comb. The degeneracy control module includes an analysis controller, a stress controller, and a degeneracy detector that are communicatively connected. The analysis controller is used to calculate the center frequency of the optical frequency comb obtained by exciting the diamond crystal and the theoretical applied stress value F0 according to the set parameters, and generate a spectrum diagram P0 of the multi-mode laser optical frequency comb under theoretical conditions; The stress controller includes a stress shaping feedback sheet, a diamond anvil, a stress applicator, a radiation detector, a detection radiation transmitter coaxially arranged with the stress application surface, and a radiation feedback controller. The radiation feedback controller receives the theoretical applied stress value F0 signal and transmits it to the stress applicator. The stress applicator applies the theoretical applied stress value F0 to the diamond crystal through the diamond anvil and the stress shaping feedback plate; The detection ray transmitter emits detection rays, which react with the stress shaping feedback plate and the diamond crystal to cause diffraction. The ray detector feeds back the detected diffraction signal to the ray feedback controller, calculates the actual applied stress value F1, and the stress difference value ΔF1 between the actual applied stress value F1 and the theoretical applied stress value F0, and adjusts the stress applied by the stress applicator according to the stress difference value ΔF1. The degeneracy detector includes an excitation laser light source, a frequency detector, and a spectrum analysis controller. The excitation laser light source excites the diamond crystal to generate the multi-mode laser optical frequency comb and transmits it to the frequency detector. The frequency detector detects the spectrum of the multi-mode laser optical frequency comb and transmits it to the spectrum analysis controller. The spectrum analysis controller analyzes and obtains an actual spectrum graph P1 and transmits it to the analysis controller. The analysis controller analyzes the spectrum width spacing difference Δv between the actual spectrum graph P1 and the spectrum graph P0 of the multi-mode laser optical frequency comb under the theoretical conditions. n , and according to the spectral width spacing difference value Δv n , calculate the stress deviation ΔF2 and feed it back to the stress controller, and adjust the stress applied by the stress applicator according to the stress difference value ΔF2; The optical frequency comb generation module is used to pump the stressed diamond crystal to generate a single-mode or multi-mode optical frequency comb, wherein the multi-mode optical frequency comb includes a plurality of single-mode optical frequency combs with different spectral widths.

2. The multi-mode laser frequency comb device according to claim 1, characterized in that: It includes a Raman resonant cavity mirror, wherein the Raman resonant cavity mirror includes a first Raman resonant cavity mirror and a second Raman resonant cavity mirror arranged on both sides of the light-transmitting end face of the diamond crystal, and the first Raman resonant cavity mirror and the second Raman resonant cavity mirror are coated cavity mirrors; or The two light-transmitting end faces of the diamond crystal are film-coated end faces.

3. The multi-mode laser frequency comb device according to claim 1, characterized in that: It includes a beam shaping mirror, which shapes the pump laser and the optical frequency comb beam and is optically coaxially placed with the pump laser or the laser optical frequency comb.

4. The multi-mode laser frequency comb device according to claim 1, characterized in that: The degeneracy detector further includes a Raman enhancement cavity mirror, which includes a first Raman enhancement cavity mirror and a second Raman enhancement cavity mirror arranged on both sides of the light-transmitting end face of the diamond crystal, and the first Raman enhancement cavity mirror and the second Raman enhancement cavity mirror are coated cavity mirrors; or The two light-transmitting end faces of the diamond crystal are film-coated end faces.

5. The multi-mode laser frequency comb device according to claim 1, characterized in that: The theoretical applied stress value F0, the theoretical spectrum width spacing v n , the stress crystal direction satisfies: Among them, q i ,q j is the coordinate of the stress acting crystal direction, m i is the mass of the i-th atom, which is m here, H ij represents the Hamiltonian operator, A is the vibration amplitude, a ij is the position of the atomic equilibrium, t is the time, δ is the displacement of the atomic principle equilibrium position, v n is the nth spectral width spacing, n is the working degeneracy, n = 1, 2, 3.

6. The multi-mode laser frequency comb device according to claim 5, characterized in that: The theoretical spectral width spacing v n The corresponding diamond crystal Raman activity intensity I raman satisfy: in, is the linear polarizability α ij The derivative with respect to the normal coordinate Q of the Raman-active vibrational mode; is the variation of the first-order nonlinear polarizability with the derivative of the linear polarizability diagonal tensor element with respect to the normal coordinate Q; is the variation of the first-order nonlinear polarizability with the derivatives of all tensor elements of the linear polarizability with respect to the normal coordinate Q.

7. The multi-mode laser frequency comb device according to any one of claims 1 to 6, characterized in that: The multi-mode laser frequency comb includes one spectral width spacing or multiple spectral width spacings.

8. The multi-mode laser frequency comb device according to any one of claims 1 to 6, characterized in that: The multi-mode laser frequency comb includes laser light of one frequency or multiple frequencies.

9. The multi-mode laser frequency comb device according to any one of claims 1 to 6, characterized in that: The stress controller also includes a stress protection component, which is arranged between the two stress shaping feedback plates and located on the non-light-emitting surface on the side of the diamond crystal. The tensile fracture stress and compressive fracture stress of the stress protection component are both weaker than those of the diamond crystal. The stress protection component is communicatively connected to the analysis controller. When the stress protection component is not broken, a positive correlation signal is transmitted to the analysis controller. When the stress protection component is broken, a negative correlation signal is transmitted to the analysis controller. When the analysis controller receives the negative correlation signal, it stops the stress controller from applying stress to the diamond crystal.

10. A degenerate multi-mode control method for a multi-mode laser optical frequency comb device according to any one of claims 1 to 9, characterized in that: The degenerate multi-mode control method includes: Step 1: Set the parameters of the analysis controller, including the pump laser wavelength, the theoretical spectrum width spacing v n , stress action crystal direction, preset stress difference value, preset spectral width spacing difference value, working degeneracy n, the analysis controller calculates the center frequency of the excited optical frequency comb and the theoretical applied stress value F0 according to the parameters, and generates a spectrum diagram P0 of the multi-mode laser optical frequency comb under theoretical conditions; Step 2: applying stress to the diamond crystal, the analysis controller transmitting the theoretical applied stress value F0 to the stress applicator through the ray feedback controller, and the stress applicator applying the theoretical applied stress value F0 to the stress shaping feedback piece and the diamond crystal through the diamond anvil; Step 3: Detecting the stress applied to the diamond crystal, the detection ray transmitter emits a detection ray, which reacts with the stress shaping feedback plate and the diamond crystal to cause diffraction, and the ray detector feeds back the detected diffraction ray signal to the ray feedback controller. The ray feedback controller screens and analyzes the diffraction ray signal, calculates the actual applied stress value F1 using the diffraction ray signal of the stress shaping feedback plate, analyzes the stress difference value ΔF1 between the actual applied stress value F1 and the theoretical applied stress value F0, and transmits the stress difference value ΔF1 to the stress applicator. Repeat steps 2 and 3 until the stress difference value ΔF1 is less than a preset stress difference value. Step 4: Detect and control the degeneracy of the diamond crystal. The excitation laser light source emits laser light to excite the diamond crystal to generate an optical frequency comb. The frequency detector detects the spectrum of the multi-mode laser optical frequency comb and transmits it to the spectrum analysis controller. The spectrum analysis controller analyzes and obtains an actual spectrum graph P1, and transmits it to the analysis controller. The analysis controller analyzes the spectral width spacing difference Δv between the actual spectrum graph P1 and the spectrum graph P0 of the multi-mode laser optical frequency comb under the theoretical conditions. n The analysis controller is based on the spectrum width spacing difference value Δv n , calculate the stress deviation ΔF2 and transmit it to the stress controller, adjust the stress applied by the stress applicator according to the stress difference value ΔF2; repeat steps 2, 3, and 4 until the spectral width spacing difference value Δv n smaller than the preset spectral width spacing difference value; Step 5: Generate a multi-mode optical frequency comb. The degeneracy detector stops working, the optical frequency comb generation module starts working, the pump laser light source emits pump laser to pump the diamond crystal to generate a multi-mode laser optical frequency comb. The remaining part of the pump laser and the multi-mode laser optical frequency comb are transmitted to the optical comb detector. The optical comb detector analyzes and obtains the required actual spectrum diagram, and transmits it to the analysis controller to obtain the required actual spectrum diagram.

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