CN117543335A - Integrated tunable external cavity ultra-narrow linewidth DBR laser - Google Patents
Integrated tunable external cavity ultra-narrow linewidth DBR laser Download PDFInfo
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Abstract
The invention provides an integrated tunable external cavity ultra-narrow linewidth DBR laser, which relates to the technical field of lasers and comprises a power supply part, a power supply part and a temperature control part, wherein the power supply part comprises a current source and a temperature control source; the ultra-narrow linewidth laser core comprises DBR laser, aspheric lens, si 3 N 4 A chip and a fiber microlens; the measuring part comprises an optical isolator, a spectrometer, an acousto-optic modulator and a spectrometer, wherein the part output from the ultra-narrow linewidth laser core is separated from optical interference by the optical isolator and then is divided into a first path and a second path, wherein one end of the first path passes through Si 3 N 4 The transmission spectrum after the chip coupling is collected, and the second path is used for converting the optical signal into an electric signal through the acousto-optic modulator and accessing the electric signal into the spectrometer through the single-mode fiber. The invention has the beneficial effects of compact and integrated structure and easy realizationThe external cavity feedback of the laser device increases the potential detection distance, and the generated narrow linewidth laser can replace an optical pumping solid laser to carry out the application of spatial coherent optical communication.
Description
Technical Field
The invention relates to the technical field of lasers, in particular to an integrated tunable external cavity ultra-narrow linewidth DBR laser.
Background
With the development and progress of optical information technology and the increasing demand for communication bandwidth, optical networks evolve from static networks with a single transmission function to dynamic networks with both transmission and routing functions. For narrow linewidth lasers, solid state, fiber and semiconductor lasers are the three most commonly used types: solid state lasers and fiber lasers inherently have a relatively large volume and longer resonant cavity length, meaning longer photon lifetime and thus good phase/frequency noise performance is easily achieved. However, the solid and fiber lasers inevitably have larger size and weight, and the manufacturing and packaging costs are very high; in addition, they all need semiconductor lasers for optical pumping, and tunable semiconductor lasers have the characteristics of chip-level size, flexible multi-wavelength selective lasing characteristics, direct electric pumping and the like, and are outstanding from a plurality of types of lasers and become important devices in future optical networks.
The optical feedback method is a main method for realizing narrow linewidth of the current semiconductor laser, and in order to increase the effective length of the resonant cavity of the laser to reduce the linewidth, optical elements such as gratings, reflectors, fiber waveguides and the like sensitive to wavelength are used as external reflectors to reflect the emergent light of the laser. However, the laser system is too complex due to the integration of external optical elements, and the reliability of the whole laser is poor due to the high environmental stability requirements of the external feedback system and the insufficient compactness of the device.
Disclosure of Invention
The present invention aims to improve the above problems by integrating tunable external cavity ultra-narrow linewidth DBR lasers. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the application provides an integrated tunable external cavity ultra-narrow linewidth DBR laser, comprising:
the power supply part comprises a current source and a temperature control source and is used for supplying power to the integratable narrow linewidth laser;
the ultra-narrow linewidth laser core comprises DBR laser, aspheric lens, si 3 N 4 The output port of the DBR laser is connected with the input port of the aspheric lens, and the generated light beam is focused to Si through the aspheric lens 3 N 4 On chip, si 3 N 4 The output port of the chip is connected with the input port of the optical fiber micro lens;
the measuring part comprises an optical isolator, a spectrometer, an acousto-optic modulator and a spectrometer, wherein the output port of the optical fiber micro lens is connected with the input port of the optical isolator, and the output port of the optical isolator is sequentially connected with the input port of the spectrometer through the spectrometer and the acousto-optic modulator; the part output from the ultra-narrow linewidth laser core is separated by an optical isolator and then divided into a first path and a second path, wherein one end of the first path passes through Si 3 N 4 The transmission spectrum after the chip coupling is collected, and the second path is used for converting the optical signal into an electric signal through the acousto-optic modulator and accessing the electric signal into the spectrometer through the single-mode fiber.
Preferably, the DBR laser comprises a gain section, a phase modulation section and a DBR section, wherein an output port of the gain section is connected with an input port of the phase modulation section, an output port of the phase modulation section is connected with an input port of the DBR section, and an output port of the DBR section is connected with an input port of the aspheric lens;
the laser beam generated by the gain region, the phase modulation region and the DBR region is coupled into Si by an aspheric lens with the thickness of 1.5mm 3 N 4 In the chip, a tunable double micro-ring resonant cavity is integrated in the micro-ring and enters from the left end face of the chip, at the height QSi 3 N 4 Rayleigh scattering is generated in the micro-ring resonant cavity along the axial direction of the optical fiber, and the scattered light propagating backward is fed back into the DBR laser through the aspheric lens, thereby forming an outer partA cavity feedback path; finally, the laser output with ultra-narrow linewidth is obtained under the drive of the current source.
Preferably, the gain region, the phase modulation region and the DBR region all have distributed Bragg reflectors and high Q Si 3 N 4 A micro-ring resonator.
Preferably, judging whether the central resonance frequency generated in the tunable double micro-ring resonant cavity reaches the isolation frequency of the DBR laser, and if so, adjusting the electrode of the double micro-ring resonant cavity so as to adjust the feedback ratio; if not, no adjustment is required, where the feedback ratio is the effective optical feedback efficiency generated in the tunable dual micro-ring resonator.
Preferably, the laser beam enters a self-injection locking state by adjusting the phase section current and the DBR section current after passing through the tunable double micro-ring resonant cavity.
Preferably, the feedback ratio is divided into five sections, namely a first section, a second section, a third section, a fourth section and a fifth section from low to high;
when the feedback ratio exceeds 10%, the DBR laser enters the fifth section, the output laser mode is a stable single longitudinal mode with a narrower linewidth, that is, the calculation formula of the center resonant frequency represented by the lorentz function is as follows:
wherein omega is f The resonance frequency is Λ, which is the half maximum spectral linewidth, Γ (ω) is the center resonance frequency of the half maximum spectral linewidth Λ, i is a complex unit, and ω is an angular frequency.
Preferably, the dynamic response of the DBR laser under the self-injection locking state is calculated as follows:
wherein omega is 0 And ω represents the solitary point frequency and output mode of the laser diode, respectivelyOperating frequency, τ is the external round trip time, ω f Is the resonance frequency, Λ is the half maximum line width, -C eff For effective optical feedback efficiency, arctan (α) is the arctangent of the linewidth enhancement factor;
and is also provided with
C eff Indicating effective optical feedback efficiency, ω indicating the operating frequency of the output mode, τ being the external round trip time, γ being the feedback rate, α being the linewidth enhancement factor, ψ=ωτ+arctan (α) indicating the external phase delay, ψ can be used without loss 0 +ωτ, Λ is half maximum line width, ω f Is the center resonant frequency.
Preferably, the power supply part is composed of two temperature control sources and one current source;
two temperature control sources are respectively used for DBR laser and Si 3 N 4 The chip is temperature controlled and the current source is used to power the DBR laser.
Preferably, the spectrometer is of the model AQ6317C and the spectrometer is of the model R & SFSW67; the output port of the optical fiber micro lens is a single-mode optical fiber APC interface.
The beneficial effects of the invention are as follows:
the invention adopts DBR output, namely the output is single longitudinal mode, the optical power is mainly concentrated on the single longitudinal mode, the problem of mode jump caused by mode competition is reduced because of stronger FP mode caused by film coating reasons, the invention has the characteristic of wavelength tunability, the lasing wavelength is easy to align with the reflection wavelength of the fiber bragg grating, and the effective external cavity feedback is easy to realize.
The device adopted by the invention is small and compact, is easy to integrate, can provide a higher coherent range for a laser radar source by the generated narrow linewidth or low-frequency noise, increases the potential detection distance, and can replace an optical pumping solid laser to apply spatial coherent optical communication by the generated narrow linewidth laser.
According to the invention, through linear frequency modulation based on a phase MRR two-dimensional tuning method, the wavelength is continuously tuned within 1543nm-1550nm, the side mode rejection ratio can reach 34db, the inherent linewidth of 5kHz can be obtained during static operation, the structure is compact and can be integrated, and the invention can be further developed in the fields of optical fiber sensing, laser radar systems and the like.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the embodiments of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an integrated tunable external cavity ultra-narrow linewidth DBR laser device according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a tunable-range in-cold-cavity profile of an integrated tunable external-cavity ultra-narrow-linewidth DBR laser according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating PI curves of an integrated tunable external cavity ultra-narrow linewidth DBR laser according to an embodiment of the present invention;
FIG. 4 is a schematic wavelength tuning diagram of an integrated tunable external cavity ultra-narrow linewidth DBR laser according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of an external cavity laser spectrum of an integrated tunable external cavity ultra-narrow linewidth DBR laser according to an embodiment of the present invention;
fig. 6 is a schematic diagram of an external cavity laser linewidth test result of an integrated tunable external cavity ultra-narrow linewidth DBR laser according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.
Example 1:
the embodiment provides an integrated tunable external cavity ultra-narrow linewidth DBR laser.
Referring to fig. 1-6, there is shown an integrated tunable external cavity ultra-narrow linewidth DBR laser comprising:
the power supply part comprises a current source and a temperature control source and is used for supplying power to the integratable narrow linewidth laser;
the ultra-narrow linewidth laser core comprises a DBR laser, an aspherical lens, a Si3N4 chip and an optical fiber micro lens, wherein an output port of the DBR laser is connected with an input port of the aspherical lens, a generated light beam is focused on the Si3N4 chip through the aspherical lens, and an output port of the Si3N4 chip is connected with an input port of the optical fiber micro lens;
the measuring part comprises an optical isolator, a spectrometer, an acousto-optic modulator and a spectrometer, wherein the output port of the optical fiber micro lens is connected with the input port of the optical isolator, and the output port of the optical isolator is sequentially connected with the input port of the spectrometer through the spectrometer and the acousto-optic modulator; the optical interference of the part output from the ultra-narrow linewidth laser core is isolated by an optical isolator and then is divided into a first path and a second path, wherein one end of the first path is used for collecting a transmission spectrum after being coupled by a Si3N4 chip, and the second path is used for converting an optical signal into an electric signal through an acousto-optic modulator and accessing the electric signal into a spectrometer through a single-mode fiber.
The invention is composed of a power supply part, an ultra-narrow linewidth laser core and a measuring part, which jointly form a laser based on DBR and high Q Si 3 N 4 A tunable integrated semiconductor laser device coupled by a micro-ring resonant cavity (MRR), wherein an ultra-narrow linewidth laser core comprises a three-section DBR laser, the DBR laser is powered by a current source (DP 2031), a generated light beam passes through an aspheric lens with the diameter of 1.5mm and is focused on a micro-ring, the hybrid laser source adopts end face coupling, and the output of an integrated waveguide is guided by one aspheric lens and one micro-lens optical fiber. The invention has small and compact structure, easy integration and the main body part has the size of only 9mm.
Specifically, the measurement section is composed of an optical isolator, a spectrometer, an acousto-optic modulator, and a 40km delay fiber. The output of the laser is isolated from optical interference by an isolator and then is subjected to 2: the 8 beam splitter is divided into a high-power path and a low-power path, and the transmission spectrum of the MRR is collected by a spectrum analyzer (AQ 6317C) at one end of the low power path; the high power end converts the optical signal into an electric signal through an acousto-optic modulator, the electric signal is accessed into a frequency spectrograph (R & SFSW 67) through a PD through a delay optical fiber of 40km, and the linewidth of the laser can be obtained through a delay self heterodyne method.
It should be noted that the power supply part is composed of two TEC temperature control sources (Newport-LDC-3724C) and a current source (DP 2031), and the two temperature control sources respectively supply power to the three-section DBR laser and Si 3 N 4 The chip is subjected to temperature control to improve the stability of the device, and the current source is used for supplying power to the three-section DBR laser.
The tunable integrated semiconductor laser device is provided with four parts (a semiconductor laser chip, a coupling lens, a high-Q-value Si3N4 micro-ring and a micro-lens optical fiber part), and the four parts are respectively supported by a precise adjusting frame with resolution of 0.5 micrometer, so that high-precision chip alignment can be directly realized. Overall, the structure of the present invention has the distinct advantage of being compact and highly integrated compared to the conventional tunable laser aspects.
Therefore, the DBR outputs a single longitudinal mode, the optical power is mainly concentrated on the single longitudinal mode, a stronger FP mode is not caused by film plating, and the mode jump problem caused by mode competition is reduced; has the characteristic of wavelength tuning, the lasing wavelength is easy to align with the reflection wavelength of the fiber grating, and effective external cavity feedback is easy to realize, as shown in figure 2, si in the tunable range 3 N 4 The micro-ring resonant cavity cold cavity characteristic chromatograph can see that the quality factor Q is more than 10 8 The cold cavity chromatography can provide the center wavelength of the external cavity laser under different channels, so that the switching is convenient.
Specifically, the DBR laser comprises a gain area, a phase modulation area and a DBR area, wherein an output port of the gain area is connected with an input port of the phase modulation area, an output port of the phase modulation area is connected with an input port of the DBR area, and an output port of the DBR area is connected with an input port of the aspheric lens;
the laser beam generated by the gain region, the phase modulation region and the DBR region is coupled into Si by an aspheric lens with the thickness of 1.5mm 3 N 4 In the chip, a tunable double micro-ring resonant cavity is integrated in the micro-ring and enters from the left end face of the chip, at the height QSi 3 N 4 Rayleigh scattering is generated in the micro-ring resonant cavity along the axial direction of the optical fiber, and scattered light propagating backwards is fed back into the DBR laser through the aspheric lens, so that an external cavity feedback path is formed; finally, the laser output with ultra-narrow linewidth is obtained under the drive of the current source.
It should be noted that the whole working process of the external cavity laser is as follows: a three-section DBR laser (comprising three sections: gain section, phase modulation section, DBR section). Under the drive of an adjustable precision current source (DP 2031), a preliminary laser beam is generated, is precisely coupled into the Si3N4 micro-ring through an aspheric lens with the diameter of 1.5mm, enters from the left end face of the chip, and in the high-Q MRR, the intensity of an optical mode in the MRR cavity can be thousands of times higher than that of the laser beam due to the high-Q effect, so that stronger backward propagation Rayleigh scattered light is excited. The back-propagating scattered light is fed back into the three-section DBR laser through the aspheric lens, so that an external cavity feedback scheme with the main body size of only 9mm is formed. As shown in fig. 3 and 4, the DBR laser PI graph and the wavelength tuning graph show the characteristics of the laser that the wavelength can be tuned continuously at 1550 nm.
Further, the gain region, the phase modulation region and the DBR region are respectively provided with a distributed Bragg reflector and a Si3N4 micro-ring resonant cavity with a high Q value.
It should be noted that, in terms of tunability, since the three-section DBR has distributed bragg reflectors, the high Q MRR also constitutes the feedback cavity; the coexistence of the two cavities may present multiple resonant modes throughout the system.
By carefully adjusting the phase region and active gain region of the DBR laser. By combining the vernier effect of the double cavities, the multimode output mode of the DBR can be compressed into 1 single mode excitation which occupies the dominant position; the integrated waveguide is used by an aspheric lens and a micro-lens optical fiber for output guiding.
Further, judging whether the central resonance frequency generated in the tunable double micro-ring resonant cavity reaches the isolation frequency of the DBR laser, and if so, adjusting the electrode of the double micro-ring resonant cavity so as to adjust the feedback ratio; if not, no adjustment is required, where the feedback ratio is the effective optical feedback efficiency generated in the tunable dual micro-ring resonator.
Further, after the laser beam passes through the tunable double micro-ring resonant cavity, the laser beam enters a self-injection locking state by adjusting phase section current and DBR section current. As shown in fig. 5, fig. 5 is a spectrum diagram of an external cavity laser, after passing through a micro-ring resonant cavity, the side mode of the laser is well inhibited by adjusting phase section current and DBR section current to enter a self-injection locking state, and the spectrum shows a significant single peak, and the side mode inhibition ratio (SMSR) is 34db.
Further, the feedback ratio is divided into five sections, namely a first section, a second section, a third section, a fourth section and a fifth section from low to high; the feedback strength can be improved by adjusting the MRR electrode when the MRR center resonant frequency is close to the isolated frequency of the DBR laser.
Wherein when the feedback ratio exceeds 10%, the DBR laser enters the fifth section, the output laser mode is a stable single longitudinal mode with narrow linewidth, in this state, the MRR function in the laser can be simplified into two parameters, namely the central resonance frequency of half maximum linewidth (FWHM) Λ, the resonance frequency omega f Defined as the frequency offset from the isolated laser. Namely, the calculation formula of the center resonance frequency expressed by the Lorentz function is as follows:
wherein omega is f The resonance frequency is Λ, which is the half maximum spectral linewidth, Γ (ω) is the center resonance frequency of the half maximum spectral linewidth Λ, i is a complex unit, and ω is an angular frequency.
Further, the dynamic response of the DBR laser under the self-injection locking state is calculated as follows:
wherein omega is 0 And ω represents the solitary point frequency and the operating frequency of the output mode of the laser diode, respectively, τ is the external round trip time, ω f Is the resonance frequency, Λ is the half maximum line width, -C eff For effective optical feedback efficiency, arctan (α) is the arctangent of the linewidth enhancement factor;
and is also provided with
C eff Indicating effective optical feedback efficiency, ω indicating the operating frequency of the output mode, τ being the external round trip time, γ being the feedback rate, α being the linewidth enhancement factor, ψ=ωτ+arctan (α) indicating the external phase delay, ψ can be used without loss 0 +ωτ, Λ is half maximum line width, ω f Is the center resonant frequency.
In particular, for the laser proposed by the invention, the phase thermode and the MRR thermode can respectively make ψ 0 And omega f And (5) detuning. The lock state is the result of synchronous tuning of the phase and MRR electrodes by solving for ω f And ω. As shown in fig. 6, the linewidth of the external cavity laser is 5KHz by the delay self heterodyne method. In the future, the laser linewidth can be reduced better by improving the value of the quality factor Q.
It should be noted that, this structure not only can realize single mode selection, but also can realize line width narrowing due to the introduction of the external cavity structure.
Further, the power supply part consists of two temperature control sources and a current source;
two temperature control sources are respectively used for DBR laser and Si 3 N 4 The chip is temperature controlled and the current source is used to power the DBR laser.
Further, the spectrometer is of the model AQ6317C, and the spectrometer is of the model R & SFSW67.
Further, the output port of the optical fiber micro lens is a single-mode optical fiber APC interface.
In summary, the DBR outputs a single longitudinal mode, which reduces the mode jump problem caused by mode competition; the laser wavelength is easy to align with the reflection wavelength of the fiber bragg grating, so that effective external cavity feedback is easy to realize; the device is small and compact, is easy to integrate, can provide a higher coherent range for a laser radar source by generated narrow linewidth or low-frequency noise, increases the potential detection distance, and can replace an optical pumping solid laser to apply spatial coherent optical communication by generated narrow linewidth laser.
It should be noted that, regarding the apparatus in the above embodiments, the specific manner in which the respective modules perform the operations has been described in detail in the embodiments regarding the method, and will not be described in detail herein.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.
Claims (10)
1. An integrated tunable external cavity ultra-narrow linewidth DBR laser comprising:
the power supply part comprises a current source and a temperature control source and is used for supplying power to the integratable narrow linewidth laser;
the ultra-narrow linewidth laser core comprises DBR laser, aspheric lens, si 3 N 4 The output port of the DBR laser is connected with the input port of the aspheric lens, and the generated light beam is focused to Si through the aspheric lens 3 N 4 On chip, si 3 N 4 The output port of the chip is connected with the input port of the optical fiber micro lens;
the measuring part comprises an optical isolator, a spectrometer, an acousto-optic modulator and a spectrometer, wherein the output port of the optical fiber micro lens is connected with the input port of the optical isolator, and the output port of the optical isolator is sequentially connected with the input port of the spectrometer through the spectrometer and the acousto-optic modulator; the part output from the ultra-narrow linewidth laser core is separated into a first path and a second path after the optical interference is isolated by an optical isolator, wherein the first pathOne end will pass through Si 3 N 4 The transmission spectrum after the chip coupling is collected, and the second path is used for converting the optical signal into an electric signal through the acousto-optic modulator and accessing the electric signal into the spectrometer through the single-mode fiber.
2. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 1, wherein the DBR laser comprises a gain section, a phase modulation section, and a DBR section, wherein an output port of the gain section is connected to an input port of the phase modulation section, an output port of the phase modulation section is connected to an input port of the DBR section, and an output port of the DBR section is connected to an input port of the aspheric lens;
the laser beam generated by the gain region, the phase modulation region and the DBR region is coupled into Si by an aspheric lens with the thickness of 1.5mm 3 N 4 In the chip, a tunable double micro-ring resonant cavity is integrated in the micro-ring and enters from the left end face of the chip, at the height QSi 3 N 4 Rayleigh scattering is generated in the micro-ring resonant cavity along the axial direction of the optical fiber, and scattered light propagating backwards is fed back into the DBR laser through the aspheric lens, so that an external cavity feedback path is formed; finally, the laser output with ultra-narrow linewidth is obtained under the drive of the current source.
3. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 2 wherein the gain region, phase modulation region, and DBR region each have a distributed bragg reflector and high Q Si therein 3 N 4 A micro-ring resonator.
4. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 2, wherein determining if a center resonant frequency generated in the tunable dual micro-ring resonator reaches an isolated frequency of the DBR laser, and if so, adjusting an electrode of the dual micro-ring resonator to adjust a feedback ratio; if not, no adjustment is required, where the feedback ratio is the effective optical feedback efficiency generated in the tunable dual micro-ring resonator.
5. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 2 wherein the laser beam enters the self-injection locking state by adjusting the phase section current and the DBR section current after passing through the tunable dual micro-ring resonator.
6. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 4, wherein the feedback ratio is divided into five sections, from low to high, first, second, third, fourth and fifth sections, respectively;
when the feedback ratio exceeds 10%, the DBR laser enters the fifth section, the output laser mode is a stable single longitudinal mode with a narrower linewidth, that is, the calculation formula of the center resonant frequency represented by the lorentz function is as follows:
wherein omega is f The resonance frequency is Λ, which is the half maximum spectral linewidth, Γ (ω) is the center resonance frequency of the half maximum spectral linewidth Λ, i is a complex unit, and ω is an angular frequency.
7. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 5 wherein the dynamic response of the DBR laser under the self-injection locking state is calculated as follows:
wherein omega is 0 And ω represents the solitary point frequency and the operating frequency of the output mode of the laser diode, respectively, τ is the external round trip time, ω f Is the resonance frequency, Λ is the half maximum line width, -C eff For effective optical feedback efficiency, arctan (α) is the arctangent of the linewidth enhancement factor;
and is also provided with
C eff Indicating effective optical feedback efficiency, ω indicating the operating frequency of the output mode, τ being the external round trip time, γ being the feedback rate, α being the linewidth enhancement factor, ψ=ωτ+arctan (α) indicating the external phase delay, ψ can be used without loss 0 +ωτ, Λ is half maximum line width, ω f Is the center resonant frequency.
8. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 1 wherein the power section consists of two temperature controlled sources and one current source;
two temperature control sources are respectively used for DBR laser and Si 3 N 4 The chip is temperature controlled and the current source is used to power the DBR laser.
9. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 1 wherein the spectrometer is model number AQ6317C and the spectrometer is model number R & SFSW67.
10. The integrated tunable external cavity ultra-narrow linewidth DBR laser of claim 1, wherein the output port of the fiber microlens is a single mode fiber APC interface.
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