Laser device, method and application

Abstract

A laser device and control method provide mode-hopping-free laser wavelength (frequency) tuning over a wide frequency band of the gain bandwidth of the gain medium, and possibly the entire gain bandwidth of the gain medium. In general, the apparatus and method include reverse dispersion to compensate for wavelength dependent group delay and group velocity dispersion within the laser cavity to achieve broadband mode hopping free wavelength tuning.

Description

[0001] Related applications This application claims priority to U.S. Provisional Application S / N 63 / 557,900, filed February 26, 2024, and U.S. Provisional Application S / N 63 / 634,994, filed April 17, 2024, the subject matter of which is incorporated herein by reference in its entirety to the full extent permitted by law. Technical Field

[0002] The embodiments and aspects of this application most generally relate to the field of laser science, more specifically to laser devices, methods and applications, and most specifically to laser devices and related control methods and applications capable of achieving mode-hopping-free tuning over a wide bandwidth of the gain bandwidth of the laser gain medium. Background Technology

[0003] Wavelength-tunable narrow-linewidth semiconductor lasers are fundamental to numerous critical applications, including but not limited to optical communications, LiDAR, atomic and optical clocks, spectral sensing, optical coherence tomography, and metrology. Tunable narrow-linewidth semiconductor lasers are typically external cavity diode lasers (ECDLs), where a low-loss external laser cavity supports narrow-linewidth laser operation, with the laser wavelength selected and tuned by a narrow-bandwidth optical filter embedded within the laser cavity. ECDLs can be constructed in free space from discrete optical components, where broadband wavelength tuning is achieved by mechanically rotating gratings along with other known optical components, thereby changing the selected laser wavelength. Such free-space ECDLs are bulky, slow in wavelength tuning, and susceptible to external mechanical disturbances, generally unsuitable for many practical applications. On-chip tunable ECDLs solve these problems by integrating all laser cavity components on a chip-level platform, offering significant advantages in size, weight, power consumption, and cost. In on-chip integrated ECDLs, wideband wavelength tuning is typically achieved through the vernier effect between a pair of sampling gratings, a superstructure grating, or dual / multi-ring microresonators within the laser cavity. However, achieving continuous wavelength tuning across a wide spectral band without laser mode hopping is not a trivial problem. This is because maintaining a constant number of laser modes during wavelength tuning is difficult. While vernier wavelength tuning structures can tune wavelengths over a wide spectral range, they do not support mode-hop-free (MHF) operation. In on-chip integrated lasers, MHF wavelength tuning requires complex coordination and control of the vernier wavelength tuning structure along with the phase shifter section embedded in the laser cavity. However, this approach remains challenging for achieving wideband MHF tuning. Furthermore, significant power is required to tune the phase shifter section. Currently, the widest MHF tuning range of integrated lasers is limited to approximately 3 nm in the telecommunication band around 1550 nm, which already requires a significant power of approximately 1 watt to tune the thermo-optical phase shifter. The inventors recognized that laser devices and methods enabling wideband MHF wavelength tuning of on-chip integrated lasers across the entire laser gain bandwidth would provide a solution to the known deficiencies of the prior art and offer advantages for a wide range of beneficial applications. The aspects and embodiments described below and in the appended claims provide for this solution. Summary of the Invention

[0004] One aspect is a method for controlling a laser device to provide mode-hopping-free (MHF) laser wavelength tuning over a wide gain bandwidth (potentially the entire gain bandwidth) of a laser gain medium. According to a non-limiting exemplary embodiment, the method includes the step of: providing a laser device having a length of L g The gain part, with a length ofL p The system comprises a passive waveguide section, an optical filter section, and a phase compensation section. The gain section provides optical gain within its gain bandwidth. The passive waveguide section forms an external laser cavity. The optical filter section selects and controls the laser frequency ω. The phase compensation section is suitable for assisting laser frequency tuning. The gain section, passive waveguide section, and optical filter section are configured to provide optical gain within their respective gain bandwidths. ω The following introduces phase shifts respectively , , (in M f (where is an integer), and These are the propagation constants of the gain portion and the passive waveguide portion, respectively; and wherein the phase compensation portion is adapted to introduce a phase shift. (ω), the phase shift (ω) satisfies the following condition: ,in, ω 0 is the reference light frequency within the gain bandwidth tuning frequency range, thereby enabling the method to achieve mode-free (MHF) tuning of the laser within the gain bandwidth. According to various alternative exemplary and non-limiting embodiments, the method may include the following additional steps, limitations, characteristics, or features, which may be used individually or in combination (multiple) as understood by those skilled in the art: - And the phase compensation part satisfies the following conditions: ,in , ( j=g,p )yes Below n Dispersion coefficient; - It also includes a phase compensation section designed according to the following conditions to compensate for both the first-order and second-order dispersions of the gain section and the passive waveguide section: ; - Also includes: designing a passive waveguide section that has a group velocity dispersion with a compensated gain portion, wherein ; and design a phase compensation section so that the phase compensation section has a phase shift that varies linearly with frequency, i.e. ; - It also includes a phase compensation section designed according to the following conditions to compensate for both the first-order and second-order dispersions of the gain section and the passive waveguide section: ; - This also includes designing a passive waveguide section that has a group velocity dispersion with a compensated gain portion, wherein ; and design a phase compensation section so that the phase compensation section has a phase shift that varies linearly with frequency, i.e. ; - The optical filter section described therein consists of two vernier ring resonators, namely ring 1 and ring 2, wherein ring 1 has a frequency of {ω}. 1i} ( i = 1, 2, ...), an optical resonator group with a free spectral range (FSR) of FSR1, and ring 2 having a frequency of {ω 2i} ( i = 1, 2, ...), an optical resonant group with a free spectral range (FSR) of FSR2, the method further includes: using a periodic time waveform with period T0 to set the resonant frequency ω of ring 1. 1i Tuning is performed within the frequency tuning range of FSR1; and within the rise time segment, the same periodic time waveform with period T0 is used to tune the resonant frequency ω of loop 2. 2i Tuning is performed within the frequency tuning range of FSR1, and during the fall time interval, the resonant frequency ω of ring 2 is set. 2i Adjust the FSR2 level back until it reaches the specified value. After one cycle, the resonant frequency of ring 2 is adjusted back. m The amount of (FSR1 - FSR2) + FSR2 is used to reset the value to its original value. - The periodic time waveforms are selected from a group including sawtooth waves, triangular waves, sine waves and square waves; - It also includes tuning the vernier ring resonator by at least one of electro-optic, thermo-optic, electromechanical and piezoelectric methods; - Wherein the laser device is an external cavity distributed Bragg reflector (eDBR) laser structure, and the optical filter part is a narrowband DBR filter, the method further includes: tuning the center frequency of the DBR filter within the tuning range of the DBR filter by at least one of electro-optic, thermo-optic, electromechanical and piezoelectric methods.

[0005] One aspect is a laser device characterized by providing mode-hopping-free (MHF) laser wavelength tuning over a wide gain bandwidth (potentially the entire gain bandwidth) of a laser gain medium. According to a non-limiting exemplary embodiment, the laser device includes: a gain section having a length... L g and gain bandwidth; passive waveguide portion external laser cavity, the passive waveguide portion external laser cavity having a length L pThe optical filter section is adapted to select and control the laser frequency ω; and the phase compensation section is adapted to assist in laser frequency tuning, wherein the gain section, the passive waveguide section, and the optical filter section respectively introduce a phase shift at the laser frequency ω. , , (in M f (where the integer is an integer) and These are the propagation constants of the gain section and the passive waveguide section, respectively, and the phase compensation section is suitable for introducing a phase shift. (ω), the phase shift (ω) satisfies the following condition: ,in, ω 0 is the reference optical frequency within the gain bandwidth tuning frequency range, thereby making the laser device a mode-free (MHF) tunable laser within the gain bandwidth. According to various alternative exemplary and non-limiting embodiments, the method may include the following additional steps, limitations, characteristics, or features, which may be used individually or in combination (multiple) as understood by those skilled in the art: - And the phase compensation part is characterized by the following conditions: ,in , ( j=g,p ) yes Below Dispersion coefficient; - The passive waveguide section is characterized by its group velocity dispersion compensation gain section, wherein... Furthermore, phase compensation is characterized by a phase shift that varies linearly with frequency, i.e. .

[0006] - Furthermore, the passive waveguide section is characterized by its group velocity dispersion compensation gain section, wherein... ; and the characteristic of phase compensation is that it has a phase shift that varies linearly with frequency, i.e. ; - The phase compensation section is characterized by the phase shift of both the first-order and second-order dispersions of the compensation gain section and the passive waveguide section, according to the following conditions: ; - Furthermore, the phase compensation section is characterized by compensating for the phase shifts of both the first-order and second-order dispersions of the gain section and the passive waveguide section, which are defined according to the following conditions: ; - The phase compensation part is a chirped Bragg grating; - Further includes a tuning electrode operatively integrated with a chirped Bragg grating; - The optical filter section consists of two vernier ring resonators, namely ring 1 and ring 2, where ring 1 has a frequency of {ω}. 1i} ( i = 1, 2, ...), an optical resonator group with a free spectral range (FSR) of FSR1, and ring 2 having a frequency of {ω 2i} ( i = 1, 2, ...), optical resonator group with free spectral range (FSR) of FSR2; - It also includes an external cavity distributed Bragg reflector (eDBR) laser structure, in which the optical filter part is a narrowband DBR filter; - It also includes a tuning electrode with a chirped Bragg grating operatively integrated; - It also includes a phase shifter disposed within the laser cavity; - The gain section is a reflective semiconductor optical amplifier (RSOA), and the external cavity photonic integrated circuit (PIC) chip is operationally integrated with the RSOA. The laser device includes optical filters in the form of at least two vernier microring resonators, a passive waveguide section, and a phase compensation section in the form of a chirped Bragg grating reflector end mirror with dispersion characteristics described by the following formula: ; - The gain component is a reflective semiconductor optical amplifier (RSOA), and the RSOA operatively integrates an external cavity photonic integrated circuit (PIC) chip. The laser device includes the optical filter in the form of at least two vernier microring resonators, exhibiting group velocity dispersion. The passive waveguide section and the phase compensation section in the form of a chirped Bragg grating reflector end mirror with dispersion characteristics described by the following formula:

[0007] - Wherein, the PIC has a material platform selected from the group consisting of: silicon, silicon nitride, silicon oxide, silicon carbide, lithium niobate (LiNbO3), lithium tantalate (LiTaO3), potassium niobate (KNbO3), III-V semiconductors (AlN, GaN, GaP, GaAs, AlGaAs, InP), barium titanate (BaTiO3), lead zirconate titanate (PZT), tantalum pentoxide (Ta2O5), aluminum oxide (Al2O3), or a composite dielectric formed by integrating one of these materials with a dielectric material such as silicon nitride or silicon dioxide.

[0008] - It also includes a tuning electrode with a chirped Bragg grating operatively integrated; - It also includes a phase shifter disposed within the laser cavity; - It also includes end-face reflectors, where the gain elements are heterogeneously integrated on top of the external cavity waveguide structure; - Among them, the end face reflector is a Sagnac mirror. - One of the end-face reflectors is at least two vernier microring resonators, and the other end-face mirror is a chirped Bragg grating reflector. Attached Figure Description

[0009] Figure 1 shows a schematic diagram of an on-chip integrated semiconductor laser structure known in the art.

[0010] Figure 2 A schematic diagram of an integrated laser structure for broadband MHF tuning is shown, based on a non-limiting example.

[0011] Figure 3 A schematic diagram of an integrated laser structure for broadband MHF tuning, with tuning electrodes connected to a chirped Bragg grating set, is shown according to a non-limiting example.

[0012] Figure 4 A schematic diagram of an integrated laser structure for broadband MHF tuning, based on a non-limiting example, is shown, which has a phase shifter embedded in the laser cavity.

[0013] Figure 5 A schematic diagram of an integrated laser structure for broadband MHF tuning, based on a non-limiting example, is shown, which has a gain element heterogeneously integrated on top of an external laser cavity PIC.

[0014] Figure 6 A schematic diagram of an integrated laser structure for broadband MHF tuning, based on a non-limiting example, is shown, featuring heterogeneously integrated gain elements and two vernier microring resonators serving as end-face mirrors.

[0015] Figure 7 A schematic diagram of the resonant tuning waveforms of two vernier ring resonators according to a non-limiting example is shown for achieving broadband MHF tuning of a laser frequency. The upper waveform (blue curve) shows the resonant tuning waveform of ring 1, and the lower waveform (red curve) shows the resonant tuning waveform of ring 2. In the figure, the resonant tuning range of ring 1 is shown as ω. 1i FSR1 / 2 and ω 1i + FSR1 / 2, but other tuning ranges can also be used, such as ω 1i FSR1 to ω 1i or ω 1i To ω 1i+ FSR1. In the figure, FSR1 is shown as greater than FSR2, but this is for illustrative purposes only. In practical applications, FSR1 can be less than FSR2. The curves in the bottom figure schematically illustrate the corresponding time-varying laser frequency tuning according to a non-limiting example.

[0016] Figure 8 A schematic diagram of the relative frequency positions of the resonances of two vernier ring resonators during a resonant tuning period of approximately one period, according to a non-limiting example, is shown, illustrating the resonant spectra of rings 1 and 2, respectively.

[0017] Figure 9 A schematic diagram of an eDBR integrated laser structure for broadband MHF tuning is shown, based on a non-limiting example.

[0018] Figure 10 A schematic diagram of an integrated eDBR laser structure for broadband MHF tuning with integrated tuning electrodes having chirped Bragg gratings is shown, according to a non-limiting example.

[0019] Figure 11 A schematic diagram of an integrated eDBR laser structure for broadband MHF tuning with a phase shifter embedded in the laser cavity is shown, according to a non-limiting example.

[0020] Figure 12 A schematic diagram of an eDBR laser structure for broadband MHF tuning, in which the gain element is heterogeneously integrated on top of an external laser cavity PIC. Detailed Implementation

[0021] This disclosure describes methods and apparatus for wideband MHF tuning over a wide area of ​​the gain bandwidth (and in some cases advantageously over the entire gain bandwidth).

[0022] As shown in Figure 1, the integrated laser 100 typically comprises the following parts: a gain section 102 that provides optical gain for laser action; a passive waveguide section 104 that forms an external laser cavity (with end-face reflectors 110); an optical filter section 106 for wavelength tuning and control; and a phase compensation section 108 for assisting wavelength tuning. These parts operate at optical frequencies... ω Introduced separately , , and The phase shift. For a length of The gain section 102 and the length of The passive waveguide section 104, whose optical phase shift is respectively determined by... and Given, among which and These are the propagation constants for these two parts, respectively.

[0023] The inventors recognized that wideband MHF tuning could be achieved through a specially designed phase compensation section, the phase shift of which... c ( ω The following conditions must be met: , (1) in ω 0 is the reference optical frequency within the tuning frequency range.

[0024] More specifically, the propagation constants of the gain section and the passive waveguide section can be described by the following formula: ( j = g, p ),in yes place n The dispersion coefficient of order, and Therefore, equation (1) becomes: (2) On the other hand, optical filters are typically based on resonance, such as distributed Bragg gratings, microresonators, or Fabry-Perot type cavities, with a phase shift of... ( M f (where the integer is an integer). Therefore, equation (2) simplifies to: (3) Semiconductor gain chips typically have optical gain bandwidth on the order of ~(10-15) THz. Within this spectral range, second-order dispersion is usually sufficient to describe the spectral correlation phase shift of a dielectric waveguide. Therefore, equation (3) can be approximated as: (4) Exemplary embodiments include two design strategies to achieve the claimed wideband MHF tuning: 1. Design a passive waveguide section to compensate for the group velocity dispersion of the gain section, wherein... Then, a phase compensation section is designed to have a phase shift that varies linearly with frequency, i.e. .

[0025] 2: Design a phase compensation section to compensate for both the first-order and second-order dispersions of the gain section and the passive waveguide section, as shown in equation (4) above.

[0026] More specific exemplary embodiments of the design strategy for achieving the claimed wideband MHF tuning include: 1. Design a passive waveguide section to compensate for the group velocity dispersion of the gain section, wherein... Then, the phase compensation section is designed to have a phase shift that varies linearly with frequency, i.e. .

[0027] 2: Design a phase compensation section to compensate for both the first-order and second-order dispersion of the gain section and the passive waveguide section, i.e. .

[0028] In equation (4), the main influence comes from terms related to the frequency-varying linear spectral phase (or equivalently, group delay) of the gain and passive waveguide components. Typically, and Therefore, the phase compensation section needs to have a negative linear spectral phase that varies with frequency. For reference, the phase compensation section in a conventional integrated laser is a simple phase shifter waveguide section, which does not meet this condition and therefore cannot support wideband MHF tuning.

[0029] According to an exemplary embodiment, the proposed phase compensation part can be implemented using a chirped distributed Bragg grating, whose dispersion characteristics are given by equation (4). Figure 2 An example of the proposed laser structure configuration 200 is shown. The laser structure is shown as a hybrid integration of a reflective semiconductor optical amplifier (RSOA) 202 and an external cavity photonic integrated circuit (PIC) chip 212. The external laser cavity consists of a pair of vernier microring resonators 206 (as narrowband optical filters for wavelength selection and tuning), a passive waveguide section 204, and a chirped Bragg grating reflector 208 as an end-face mirror (whose dispersion characteristics are described by Equation (4)).

[0030] This specific implementation method can be applied to different external cavity PIC circuit platforms, such as silicon, silicon nitride, silicon oxide, silicon carbide, lithium niobate (LiNbO3), lithium tantalate (LiTaO3), potassium niobate (KNbO3), III-V semiconductors (AlN, GaN, GaP, GaAs, AlGaAs, InP), barium titanate (BaTiO3), lead zirconate titanate (PZT), tantalum pentoxide (Ta2O5), aluminum oxide (Al2O3), or a composite dielectric formed by integrating one of these materials with a dielectric material such as silicon nitride or silicon dioxide.

[0031] Advantageously, such as Figure 3As shown, the tuning electrode 320 can be integrated with the chirped Bragg grating 208 to achieve more precise wavelength tuning and compensate for certain manufacturing errors. The tuning mechanism can be a thermo-optical effect, electro-optical effect, electromechanical effect, or piezoelectric effect, depending on the PIC material platform. For example, as those skilled in the art will understand, thermo-optical effects can be used for silicon and silicon nitride platforms, while both thermo-optical and electro-optical effects can be used for thin-film lithium niobate and lithium tantalate platforms.

[0032] like Figure 4 In another exemplary embodiment shown, a phase shifter 422 may be operatively disposed in the laser cavity to assist laser operation and wavelength tuning if necessary.

[0033] In other exemplary embodiments, the III-V gain element can be integrated with the external laser cavity in different ways; for example, by edge coupling as shown in Figures 1-4, where the III-V gain element is shown as a reflective semiconductor optical amplifier (RSOA) 202, or, for example, by heterogeneous integration of it onto the top of the external cavity waveguide structure (e.g., Figure 5 (As shown).

[0034] Similarly, different variations can be applied to the laser cavity structure. For example, Figure 6 A vernier microring resonator 206 is shown as an end-face mirror, and a chirped Bragg grating reflector 208 is shown as another end-face mirror. Other types of phase compensation components can also be used as long as the dispersion characteristics satisfy equation (4). As those skilled in the art will understand, these same concepts and designs can be applied equally to fiber lasers and free-space lasers.

[0035] In a more general sense, the optical filter section may have a small residual spectral correlation phase. In this case, equation (4) will become: (5) More specifically, the control method for the vernier ring laser structure shown can be achieved through, as follows: Figure 7 The time waveform shown tunes the resonance of the two vernier ring resonators, achieving wideband MHF tuning of the laser frequency. Assume ring 1 has a frequency of... {ω 1i } ( i =1 , 2 ,... The optical resonator group of ring 2 has a free spectral range (FSR) of FSR1. Assume ring 2 has a frequency of... {ω 2i } ( i =1 , 2 ,...The optical resonant group of ring 1 has a free spectral range (FSR) of FSR². The two rings can be tuned via electro-optic, thermo-optic, electromechanical, or piezoelectric methods. The resonant frequency of ring 1... ω 1i Tuning is performed using a periodic frequency tuning range FSR1, for example, a periodic... T The sawtooth wave waveform of 0 is 1150-1. The resonant frequency of ring 2. ω 2i It is also periodically tuned using the same sawtooth waveform 1150-2. During the rise time interval, the resonance is tuned to the same FSR1 value as ring 1; while during the fall time interval, the resonance is tuned back to the FSR2 value. Then, after m time periods, the resonance of ring 2 is tuned back to... m (FSR1 The FSR2)+FSR2 amount is used to reset to the initial value. Figure 8 The resonant tuning is further illustrated, showing the relative frequency positions of the resonant mode spectra of the two rings when tuning occurs over approximately one cycle. Therefore, the laser frequency will be in MHF mode. ω a and ω b Continuous tuning between ( Figure 7 The time period is mT 0. Advantageously, this implementation method eliminates the need for coordinated phase shifter tuning, which not only saves significant power but also greatly simplifies the control architecture. While a sawtooth wave example is used here to describe the tuning process, other types of waveforms, such as triangle waves, sine waves, and square waves, can also be used.

[0036] In addition to the vernier ring laser structure discussed above, embodiments may also include, for example, laser structures with lasers ... Figure 9 The external cavity distributed Bragg reflector (eDBR) laser structure 900 is shown. In this case, the vernier ring-based filter is replaced by a narrowband DBR filter 906 for selecting the laser frequency. By tuning the center frequency of the DBR filter, the laser can achieve MHF tuning over a wide spectral range (limited only by the tuning range of the DBR filter).

[0037] Similarly, to more precisely tune the wavelength and compensate for certain manufacturing errors, the tuning electrode 910 can be integrated with the chirped Bragg grating 908, such as... Figure 10 As shown.

[0038] In addition, a phase shifter 922 can be added to the laser cavity to assist laser operation and wavelength tuning when necessary, such as... Figure 11 As shown.

[0039] Alternatively, the III-V gain element can be integrated with an external laser cavity using different methods, such as... Figures 9 to 11 The schematic illustration shows edge coupling (where the III-V gain element 902 is shown as a reflective semiconductor optical amplifier (RSOA)), or, for example, integrating the III-V gain element onto the top of an external cavity waveguide structure via a heterogeneous material, such as... Figure 12 As shown.

[0040] Those skilled in the art will understand that, in addition to the DBR filter illustrated, other types of tunable narrowband filters, such as Fabry-Perot filters, arrayed waveguide grating filters, etc., can also be used.

[0041] While various disclosed embodiments have been described above, it should be understood that these embodiments are merely examples and not limitations. Numerous modifications can be made to the disclosed embodiments according to this specification without departing from the spirit or scope of this specification. Therefore, the breadth and scope of this specification should not be limited to any of the foregoing embodiments; rather, the scope of this specification should be defined by the appended claims and their equivalents.

Claims

1. A method for controlling a laser, comprising: Provide a laser device, the laser device comprising having a length L g The gain portion, having a length L p The system comprises a passive waveguide section, an optical filter section, and a phase compensation section. The gain section provides optical gain within the gain bandwidth. The passive waveguide section forms an external laser cavity. The optical filter section selects and controls the laser frequency. ω The phase compensation section is suitable for assisting laser frequency tuning. Among them, the gain section, the passive waveguide section, and the optical filter section are at the laser frequency ω The following introduces phase shifts respectively , and (in M f (where is an integer), and These are the propagation constants of the gain portion and the passive waveguide portion, respectively. Furthermore, the phase compensation portion is adapted to introduce a phase shift that satisfies the following conditions. (ω): ， in, ω 0 is the reference optical frequency within the gain bandwidth tuning frequency range. This enables the method to achieve mode-free (MHF) tuning of the laser within the gain bandwidth.

2. The method according to claim 1, wherein, The phase compensation component satisfies the following conditions: ， in, , ( j=g,p )yes Below n Dispersion coefficient.

3. The method according to claim 2, further comprising: The phase compensation section is designed according to the following conditions to compensate for both the first-order and second-order dispersions of the gain section and the passive waveguide section: 。 4. The method according to claim 2, further comprising: The passive waveguide section is designed such that it has a group velocity dispersion that compensates for the group velocity dispersion of the gain section, wherein... ;as well as The phase compensation section is designed to have a phase shift that varies linearly with frequency, i.e. 。 5. The method according to claim 3, further comprising: The phase compensation section is designed according to the following conditions to compensate for both the first-order and second-order dispersions of the gain section and the passive waveguide section: .

6. The method of claim 4, further comprising: The passive waveguide section is designed such that it has a group velocity dispersion that compensates for the group velocity dispersion of the gain section, wherein... ;as well as The phase compensation section is designed to have a phase shift that varies linearly with frequency, i.e. .

7. The method according to claim 1, wherein, The optical filter section consists of two vernier ring resonators, namely ring 1 and ring 2, wherein ring 1 has a frequency of {ω}. 1i } ( i = 1, 2, ...), an optical resonator group with a free spectral range (FSR) of FSR1, and ring 2 having a frequency of {ω 2i } ( i = 1, 2, ...), an optical resonance group with a free spectral range (FSR) of FSR2, the method further includes: The resonant frequency ω of loop 1 is determined using a periodic time waveform with period T0. 1i Tuning is performed within the frequency tuning range of FSR1; and Within the rise time segment, using the same periodic time waveform with period T0, the resonant frequency ω of loop 2 is... 2i Tuning is performed within the frequency tuning range of FSR1, and during the fall time interval, the resonant frequency ω of ring 2 is set. 2i Adjust the FSR2 level back until it reaches the specified value. After one cycle, the resonance of ring 2 is tuned back. m (FSR1 The amount of FSR2)+FSR2 is used to reset the value to its original value.

8. The method according to claim 7, wherein, The periodic time waveform is selected from a group including sawtooth waves, triangular waves, sine waves and square waves.

9. The method of claim 7, further comprising tuning the vernier ring resonator by at least one of electro-optic, thermo-optic, electromechanical, and piezoelectric methods.

10. The method according to claim 1, wherein, The laser device is an external cavity distributed Bragg reflector (eDBR) laser structure, wherein the optical filter part is a narrowband DBR filter, and the method further includes: The center frequency of the DBR filter is tuned within the tuning range of the DBR filter.

11. A laser device, comprising: The gain portion has a length L g and gain bandwidth; The passive waveguide portion has an external laser cavity, which has a length L p ; The optical filter section is adapted to select and control the laser frequency ω; as well as The phase compensation section is adapted to assist in laser frequency tuning. The gain section, the passive waveguide section, and the optical filter section respectively introduce phase shift at the laser frequency ω. , and (in M f (where the integer is an integer), and These are the propagation constants of the gain portion and the passive waveguide portion, respectively. Furthermore, the phase compensation portion is adapted to introduce a phase shift that satisfies the following conditions. (ω): ， in, ω 0 is the reference optical frequency within the gain bandwidth tuning frequency range. This makes the laser device a mode-free (MHF) tunable laser within the gain bandwidth.

12. The laser device according to claim 11, wherein, The phase compensation section is characterized by the following conditions: ， in, , ( j=g,p )yes Below Dispersion coefficient.

13. The laser device according to claim 11, wherein: The passive waveguide section is characterized by compensating for the group velocity dispersion of the gain section, wherein, ;and The phase compensation is characterized by a phase shift that varies linearly with frequency, i.e. 。 14. The laser device according to claim 11, wherein: The phase compensation section is characterized by a phase shift that compensates for both the first-order and second-order dispersions of the gain section and the passive waveguide section according to the following conditions: 。 15. The laser device according to claim 11, wherein, The phase compensation component is a chirped Bragg grating.

16. The laser device of claim 15, further comprising a tuning electrode operatively integrated with the chirped Bragg grating.

17. The laser device according to claim 11, wherein, The optical filter section consists of two vernier ring resonators, namely ring 1 and ring 2, wherein ring 1 has a frequency of {ω}. 1i } ( i = 1, 2, ...), an optical resonator group with a free spectral range (FSR) of FSR1, and ring 2 having a frequency of {ω 2i } ( i = 1, 2, ...), an optical resonator group with a free spectral range (FSR) of FSR2.

18. The laser device according to claim 11, comprising an external cavity distributed Bragg reflector (eDBR) laser structure, wherein, The optical filter section is a narrowband DBR filter.

19. The laser device according to claim 11, further comprising a phase shifter disposed within the laser cavity.

20. The laser device according to claim 11, wherein, The laser cavity photonic integrated circuit (PIC) has a material platform selected from the group consisting of: silicon, silicon nitride, silicon oxide, silicon carbide, lithium niobate (LiNbO3), lithium tantalate (LiTaO3), potassium niobate (KNbO3), III-V semiconductors (AlN, GaN, GaP, GaAs, AlGaAs, InP), barium titanate (BaTiO3), lead zirconate titanate (PZT), tantalum pentoxide (Ta2O5), aluminum oxide (Al2O3), or a composite medium formed by integrating one of these materials with a dielectric material such as silicon nitride or silicon dioxide.

21. The laser device according to claim 20, wherein, The gain section is a reflective semiconductor optical amplifier (RSOA), and the RSOA operatively integrates an external cavity photonic integrated circuit (PIC) chip. The laser device includes the optical filter in the form of at least two vernier microring resonators, the passive waveguide section, and the phase compensation section in the form of a chirped Bragg grating reflector end mirror having dispersion characteristics as described by the following formula: 。 22. The laser device according to claim 20, wherein, The gain section is a reflective semiconductor optical amplifier (RSOA), and the RSOA operatively integrates an external cavity photonic integrated circuit (PIC) chip. The laser device includes the optical filter in the form of at least two vernier microring resonators, exhibiting group velocity dispersion. The passive waveguide portion and the phase compensation portion in the form of a chirped Bragg grating reflector end mirror having dispersion characteristics as described by the following formula: 。 23. The laser device of claim 21, further comprising a tuning electrode operatively integrated with the chirped Bragg grating.

24. The laser device according to claim 21 further includes a phase shifter disposed within the laser cavity.

25. The laser device of claim 21, further comprising an end-face reflector, wherein, The gain element is heterogeneously integrated on top of the external cavity waveguide structure.

26. The laser device according to claim 25, wherein, One of the end-face reflectors is one of the at least two vernier microring resonators, and the other end-face mirror is a chirped Bragg grating reflector.

27. The laser device of claim 22, further comprising a tuning electrode operatively integrated with the chirped Bragg grating.

28. The laser device according to claim 22 further includes a phase shifter disposed within the laser cavity.

29. The laser device of claim 22, further comprising an end-face reflector, wherein, The gain element is heterogeneously integrated on top of the external cavity waveguide structure.

30. The laser device according to claim 29, wherein, One of the end-face reflectors is one of the at least two vernier microring resonators, and the other end-face mirror is a chirped Bragg grating reflector.

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